Loading...
HomeMy Public PortalAboutMPSP-Stormwater Report Stormwater Deport The Arsenal Project Arsenal Street Watertown, NIA 02472 Prepared for: Boylston Properties 800 Boylston Street, Suite 1390 Boston, MA 02199 and The Wilder Companies 800 Boylston Street, Suite 1300 Boston, MA 02199 Prepared by: RJ O'CONNELL & ASSOCIATES, INC. 80 Montvale Ave, Suite 201 Stoneham, MA 02180 OF M,4SS p� JOHN J. yG STOY m CIVIL y Date: �A ,Q�No.az7s7 a July 11, 2016 S Reissued: September 13, 2016 (MPSP) Stormwater Report The Arsenal Project RIO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 Table of Contents I. Stormwater Report Narrative 1.0 Introduction................................................................................................................... 1 2.0 Site Location and Description....................................................................................... 1 3.0 Proposed Project........................................................................................................... 1 4.0 Compliance with the Massachusetts Stormwater Policy.............................................. 3 5.0 Compliance with the Town of Watertown's Requirements for Stormwater Management and Erosion Control................................................................................ 6 5.1 Stormwater Management Plan................................................................................ 6 5.2 Performance Standards ........................................................................................... 7 6.0 Soil Data...................................................................................................................... 11 7.0 Hydrologic Methodology............................................................................................ 11 8.0 Pre-Redevelopment Drainage Conditions................................................................... 12 8.1 On-Site Resources................................................................................................. 12 8.2 Pre-Redevelopment Hydrology ............................................................................ 12 8.3 Pre-Redevelopment Hydrological Conditions...................................................... 14 9.0 Post-Redevelopment Drainage Conditions................................................................. 14 9.1 Post-Redevelopment Hydrology........................................................................... 14 9.2 Post-Redevelopment Hydrological Conditions..................................................... 17 9.3 Groundwater Recharge ......................................................................................... 20 9.4 Stormwater Quality............................................................................................... 21 10.0 Summary..................................................................................................................... 22 10.1 Stormwater Management System Design............................................................. 23 10.2 Water Quality........................................................................................................ 24 10.3 Operation and Maintenance Plan.......................................................................... 24 Page i Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 II. Figures Figure 1 —USGS Site Locus Map Figure 2—NRCS Web Soil Survey Map Figure 3 —FEMA Flood Insurance Rate Map Figure 4—Natural Heritage and Endangered Species Program Map Figure 5 —Wellhead Protection Map Figure 6—Pre-Redevelopment Watershed Plan Figure 7—Post-Redevelopment Watershed Plan Figure 7A—Future Post-Redevelopment Watershed Plan III. Appendices A MassDEP Checklist for Stormwater Report B Soils Information prepared by McPhail Associates, LLC. C Letter prepared by Linenthal Eisenberg Anderson, Inc. Engineers (LEA) D Computations Pre-Redevelopment Hydrological Computations Post-Redevelopment Hydrological Computations Future Post-Redevelopment Hydrological Computations E Performance Data F Stormwater Pollution Prevention Plan (SWPPP) -will be finalized and submitted before construction commences G Operation and Maintenance Plan(O&M) with Long Term Pollution Prevention Plan (LTPPP) Page ii L STORMWATER REPORT NARRATIVE Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 1.0 Introduction RJO'Connell &Associates, Inc. (RJOC)has prepared this stormwater report on behalf of Boylston Properties and The Wilder Companies for the proposed redevelopment of The Arsenal Mall located on Arsenal Street in Watertown, Massachusetts (refer to Figure 1, "USGS Site Locus Map"). This study uses the computer program HydroCAD, version 10.00 based on the Natural Resources Conservation Service (MRCS), formerly the Soil Conservation Service (SCS) TR-20 Computer Program for Project Formulation Hydrology, to model pre-redevelopment and post-redevelopment hydrologic site conditions. This report presents a comparative analysis of the pre-redevelopment hydrologic condition to the post-redevelopment condition, and demonstrates that the redeveloped condition will be a significant improvement over the pre-redevelopment condition. This report will also demonstrate the project's compliance with the Massachusetts Stormwater Policy and the Town of Watertown's Requirements for Stormwater Management and Erosion Control to the maximum extent practicable. 2.0 Site Location and Description The proposed project is located at the 693,053 square foot(15.910 acre) Mall Lot 2—Phase A, and the 136,920 square foot(3.143 acre) Harvard Vanguard Medical Associates (HVMA) Lot 2A,both located on Arsenal Street in Watertown, Massachusetts. The parcels are identified by the Watertown Assessor's Office as 1301-2D-2 and 1301-2A-1 respectively. The site is bounded by Arsenal Street on the north, Greenough Boulevard and the Charles River on the east, Watertown park land and the Charles River on the south, and Harvard Vanguard Medical Associates on the west. The project site also encircles the Home Depot parcel located at 615 Arsenal Street. The site is currently occupied by the existing Arsenal Mall, which is comprised of a±178,200 square foot, 2-story brick building and a±83,140 square foot, 2-story brick building. Also located on-site are approximately 583 paved parking spaces for employees and customers. This site is unique in that stormwater runoff from the site is directed to two differently regulated areas. Under existing conditions, runoff from the north and west portions of the site, and the adjacent HVMA parcel, discharges into the Town of Watertown's storm drain system in Arsenal Street at Point of Analysis 1 (POA-1). This drainage system is regulated by the Town of Watertown's Requirements for Stormwater Management and Erosion Control. Runoff from the remaining east and south portions of the site collects in one of three drain pipes owned by the Massachusetts Department of Conservation and Recreation (DCR),which all ultimately discharge into the Charles River. The DCR is a state agency, and as such is regulated by the Massachusetts Stormwater Policy. 3.0 Proposed Project The proposed project consists of the partial demolition of the two existing Arsenal Mall buildings, and the construction of six new buildings on the site. The±178,200 square foot existing Building A will be partially demolished, with publicly accessible open space and a ±59,845 square foot proposed Building F to be constructed in its place. Existing Building A will be reduced to an approximate footprint of 83,100 square feet. The±83,140 square foot existing Page 1 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 building will also be partially demolished and reduced to a footprint of±72,480 square feet with the f1,500 square foot proposed Building E2 serving as a detached appendage. Proposed Building B will be five stories tall with an approximate footprint of 68,040 square feet. Proposed Buildings C and D will also be five stories tall with approximate footprints of 31,700 square feet and 25,600 square feet respectively. Proposed Building G will be a 13-story residential building with a footprint of approximately 15,640 square feet. Parking will be reconfigured into primarily structured parking to provide for a more pedestrian- friendly and handicap accessible environment with only a few small surface parking lots. Three subsurface parking garages will be constructed, one below proposed Building B, one below proposed Buildings C and D, and one below proposed Building F. Two above-ground parking garages will be constructed above proposed Buildings B and F. Existing site entrances and exits off Arsenal Street will remain in their present locations, but be reconfigured to provide easier and more efficient ingress to and egress from the site. New utilities, including water, sanitary sewer, electric, and telephone,will be installed as part of the phased construction process. Utility corridor locations will be limited due to phased construction, which is required to fulfill the terms of existing tenant leases. These leases require tenants to remain open during the first, second, or in some cases, all of the proposed construction phases. The proposed subsurface parking garages and required utility corridors severely limit the opportunity to install infiltration Best Management Practices (BMPs). However, a stormwater management system has been designed in compliance with the Massachusetts Stormwater Policy and the Town of Watertown's Requirements for Stormwater Management and Erosion Control to the maximum extent practicable. The proposed stormwater management system will reduce pre-redevelopment stormwater runoff peak flow rates and volumes, and improve runoff water quality. Runoff control, water quality improvement, and groundwater recharge will be accomplished by implementing the following drainage improvements: • Collect storm runoff in catch basins with deep sumps and hooded outlets; • Route runoff through oil grit separators designed to remove at least 25% TSS from the f- inch water quality volume storm. Runoff exceeding the 1-inch water quality storm will bypass treatment without backwatering the drainage system; • Construct two subsurface infiltration systems to detain and infiltrate runoff into the ground, thereby reducing peak flow rates and volumes of runoff discharged from the site and increasing groundwater recharge; The proposed stormwater management measures described above will have no adverse impacts to adjacent properties, and will result in an overall benefit to the surrounding area. Page 2 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 4.0 Compliance with the Massachusetts Stormwater Policy This redevelopment program includes a stormwater management system that will collect, pre- treat, treat, and reduce stormwater runoff in conformance with the Massachusetts Stormwater Policy. According to Standard 7, a redevelopment project is defined as follows: • "Development, rehabilitation, expansion and phased projects on previously developed sites, provided the redevelopment results in no net increase in impervious area." As a redevelopment project, the site is required to meet Standards 2 through 6 to the maximum extent practicable and fully comply with Standards 1, 8, 9, and 10. The proposed project results in a net increase in the amount of landscaped/open area by approximately 13,000 square feet, but has been designed to fully comply with all the Stormwater Management Standards as if the site was previously undeveloped. Compliance with each Standard is described below: Standard 1: No new stormwater conveyances (e.g. outfalls) may discharge untreated stormwater directly to or cause erosion in wetlands or waters of the Commonwealth. No new stormwater conveyances will be created under the proposed redevelopment program, and no untreated stormwater will discharge directly to or cause erosion in wetlands or waters of the Commonwealth. Stormwater runoff that ultimately discharges from two of the three Points of Analysis (POAs)will be collected in catch basins with deep sumps and hooded outlets, routed through oil grit separators designed to remove at least 25% TSS from the 1-inch water quality flow, and infiltrated in subsurface infiltration systems prior to discharge from the site. Runoff from the third POA will be significantly reduced under the proposed condition until a new subsurface infiltration system can be constructed on the HVMA parcel, when runoff will be eliminated from the third POA. Standard 2: Stormwater management systems shall be designed so that post-development peak discharge rates do not exceed pre-development peak discharge rates. The proposed stormwater management system has been designed so that post-redevelopment peak discharge rates and volumes do not exceed pre-redevelopment peak discharge rates and volumes. Subsurface Infiltration System 1 (SSI-1) has been designed to detain and infiltrate the 24-hour, 25-year, Cornell Extreme Precipitation rainfall until the HVMA lease expires, when a new subsurface infiltration system can be constructed on that parcel. After construction of the new subsurface infiltration system, SSI-1 will reduce the peak flow rate of runoff discharged from the site at Point of Analysis 1 (POA-1)by 95%. The watershed area and amount of impervious area within the watershed that discharges runoff to Point of Analysis 2 (POA-2)will be reduced, which will result in lower post-redevelopment peak discharge rates and volumes compared to pre-redevelopment rates and volumes. After construction of the future subsurface infiltration system on the HVMA parcel, the entire watershed area that previously discharged to POA-2 will be directed to SSI-1. This future condition will result in zero discharge from the site at POA-2. Subsurface Infiltration System 2 (SSI-2) has been designed to detain and infiltrate the 1-inch water quality volume over the impervious area within the proposed watershed, which will significantly reduce post-redevelopment peak discharge rates and volumes compared to pre- redevelopment rates and volumes at Point of Analysis 3. Page 3 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 Standard 3: Loss of annual recharge to groundwater shall be eliminated or minimized through the use of infiltration measures including environmentally sensitive site design, low impact development techniques, stormwater best management practices, and good operation and maintenance. At a minimum,the annual recharge from the post- development site shall approximate the annual recharge from pre-development conditions based on soil type. This Standard is met when the stormwater management system is designed to infiltrate the required recharge volume as determined in accordance with the Massachusetts Stormwater Handbook. Annual groundwater recharge will be increased under post-redevelopment conditions by the increase in landscaped/open area by approximately 13,000 square feet and the construction of two subsurface infiltration systems. Subsurface Infiltration System 1 (SSI-1)has been designed to detain and infiltrate significantly more runoff than the required 1-inch water quality volume. Specifically, it has been designed to recharge runoff from the 24-hour, 25-year, Cornell Extreme Precipitation rainfall until the lease on the HVMA parcel expires, and a new subsurface infiltration system can be constructed. When that future subsurface infiltration system is constructed to treat runoff associated with the HVMA parcel, SSI-1 will reduce the peak flow rate of runoff discharged from the site at Point of Analysis 1 (POA-1)by 95%. Subsurface Infiltration System 2 (SSI-2) has been designed to detain and infiltrate the required 1-inch water quality volume over the impervious area within the proposed tributary watershed. The reduction of impervious area within the tributary watershed discharging to Point of Analysis 2 under post- redevelopment conditions will result in increased annual groundwater recharge compared to pre- redevelopment conditions. Standard 4: Stormwater management systems shall be designed to remove 80% of the average annual post-construction load of Total Suspended Solids (TSS). Stormwater runoff from paved surface parking areas will be collected in catch basins with deep sumps and hooded outlets and routed through oil grit separators designed to remove at least 25% TSS from the 1-inch water quality flow prior to discharge from the site. Subsurface Infiltration Systems 1 and 2 will provide the remaining 80% TSS removal prior to discharge from the site at Points of Analysis 1 and 3. Standard 5: For land uses with higher potential pollutant loads, source control and pollution prevention shall be implemented in accordance with the Massachusetts Stormwater Handbook to eliminate or reduce the discharge of stormwater runoff from such land uses to the maximum extent practicable. If through source control and/or pollution prevention all land uses with higher potential pollutant loads cannot be completely protected from exposure to rain, snow, snow melt, and stormwater runoff, the proponent shall use the specific structural stormwater BMPs determined by the Department to be suitable for such uses as provided in the Massachusetts Stormwater Handbook. The proposed redevelopment is classified as a land use with higher potential pollutant loads (LUHPPL) due to the large-scale, mixed-use nature of the site and an anticipated parking lot with high intensity use (1,000 vehicle trips per day or more). Except for a few small surface parking lots, most parking will be provided in subsurface and above-ground garages protected from exposure to rain, snow, snowmelt, and stormwater runoff, significantly reducing the discharge of Page 4 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 stormwater with higher potential pollutant loads from the site. Stormwater Best Management Practices (BMPs) have been selected that MassDEP has determined to be suitable for pre- treating and treating runoff from exposed parking lots and access drives on-site, including: catch basins with deep sumps and hooded outlets, oil grit separators, and infiltration systems. As a result of the implementation of these BMPs, the discharge of stormwater with high potential pollutant loads will be significantly reduced in conformance with the Massachusetts Stormwater Policy. Standard 6: Stormwater discharges within the Zone II or Interim Wellhead Protection Area of a public water supply, and stormwater discharges near or to any other critical area, require the use of the specific source control and pollution prevention measures and the specific structural stormwater best management practices determined by the Department to be suitable for managing discharges to such areas, as provided in the Massachusetts Stormwater Handbook. No portion of the site is located within a Zone I, Zone II, or Interim Wellhead Protection Area of a public water supply or any other critical area. Standard 7: A redevelopment project is required to meet the following Stormwater Management Standards only to the maximum extent practicable: Standard 2, Standard 3, and the pretreatment and structural best management practice requirements of Standards 4, 5, and 6. Existing stormwater discharges shall comply with Standard I only to the maximum extent practicable. A redevelopment project shall also comply with all other requirements of the Stormwater Management Standards and improve existing conditions. The proposed project involves the redevelopment of the existing Arsenal Mall, which will result in a net decrease in impervious area on-site. However, the site has been designed to fully comply with all the Stormwater Management Standards as if the site was previously undeveloped. Standard 8: A plan to control construction-related impacts including erosion, sedimentation and other pollutant sources during construction and land disturbance activities (construction period erosion, sedimentation, and pollution prevention plan) shall be developed and implemented. A Stormwater Pollution Prevention Plan(SWPPP) to control erosion, sedimentation, and other pollutant sources, and prevent erosion and sediments from moving off-site during construction and land disturbance activities will be finalized and submitted before construction commences. A Demolition and Erosion Control Plan will also be finalized and included in the site plan set before construction commences. Standard 9: A long-term operation and maintenance plan shall be developed and implemented to ensure that stormwater management systems function as designed. An Operation and Maintenance Plan (O&M)with a Long Term Pollution Prevention Plan (LTPPP) has been developed and can be found in Appendix G. It will be implemented to ensure the long-term, post-construction operation of the stormwater management system. Page 5 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 Standard 10: All illicit discharges to the stormwater management system are prohibited. There will be no illicit discharges to the stormwater management system, and an illicit discharge compliance statement is included in the Operation and Maintenance Plan(refer to Appendix G). 5.0 Compliance with the Town of Watertown's Requirements for Stormwater Management and Erosion Control This site is unique in that stormwater runoff is directed to two differently regulated areas. Runoff from the north and west portions of the site discharges into the Town of Watertown's storm drain system in Arsenal Street at Point of Analysis 1 (POA-1),which is regulated by the Town of Watertown's Requirements for Stormwater Management and Erosion Control. Runoff from the remaining east and south portions of the site discharges to drainage pipes owned by the Massachusetts Department of Conservation and Recreation (DCR), which is regulated by the Massachusetts Stormwater Policy. The entire site has been designed in compliance with the Massachusetts Stormwater Handbook, but the stormwater management system that discharges runoff to the Town of Watertown's 30-inch storm drain in Arsenal Street at POA-1 has been designed in compliance with the more stringent Town of Watertown's Requirements for Stormwater Management and Erosion Control. 5.1 Stormwater Management Plan 5.1.1 Existing Conditions Plan An Existing Conditions Plan of the site has been prepared by Feldman Land Surveyors. The plan contains sufficient information to describe the existing surface site features and subsurface utility information, and is included in the site plan set. 5.1.2 Proposed Conditions Plan Proposed Conditions Plans of the site consisting of an Overall Site Plan, Grading and Drainage Plan, Utility Plan, and Parking and Traffic Control Plan have been prepared by RJO'Connell & Associates, Inc. and are included in the site plan set. These plans contain sufficient information to describe the proposed surface site features and subsurface utility modifications. 5.1.3 Erosion and Sediment Control Plan A Demolition and Erosion Control Plan has been prepared by RJO'Connell &Associates, Inc. The plan is included in the site plan set, and contains sufficient information to demonstrate that erosion and sedimentation will be minimized during the construction process. 5.1.4 Construction Detail Plan Construction Detail Plans have been prepared by RJO'Connell &Associates, Inc. to include Erosion Control Details, Drainage Details, Utility Details, and Site, Parking and Traffic Control Details. These details are included in the site plan set, and contain sufficient information for construction details. Page 6 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 5.1.5 Stormwater Management Report This Stormwater Report has been prepared to document compliance with the Massachusetts Stormwater Policy and the Town of Watertown's Requirements for Stormwater Management and Erosion Control to the maximum extent practicable. Compliance with the standards described in these regulations is documented in Section 4.0 and 5.0 of this report. 5.1.6 Operation and Maintenance Plan An Operation and Maintenance Plan(O&M) that describes the various components of the proposed stormwater system, identifies inspection and maintenance tasks, and provides a schedule to follow, has been developed and can be found in Appendix G. This plan will ensure the proper long-term performance of the system. 5.2 Performance Standards 5.2.1 Retention Standard Section 8.1 of the Town of Watertown's Requirements for Stormwater Management and Erosion Control states, "For all new development and redevelopment projects, stormwater management systems must be designed such that all stormwater runoff is retained on-site to the Maximum Extent Practicable (MEP)...The intent of this standard is to provide on-site stormwater retention measures (such as infiltration) for all storm events up to and including the 100-year, 24-hour storm." The stormwater management system that discharges runoff from the site at Point of Analysis 1 (POA-1)has been designed such that all stormwater runoff is retained on-site to the maximum extent practicable. Subsurface Infiltration System 1 (SSI-1) has been designed to retain and infiltrate runoff from the 24-hour, 25-year, Cornell Extreme Precipitation rainfall until the HVMA lease expires and a new subsurface infiltration system can be constructed on that parcel. When that future subsurface infiltration system is constructed to treat runoff associated with the HVMA parcel, SSI-I will reduce the peak flow rate of runoff discharged from the site at POA-1 by 95%. The stormwater management systems that discharge runoff from the site at Points of Analysis 2 and 3 (POA-2 and POA-3)have not been designed to retain and infiltrate the 24-hour, 100-year, Cornell Extreme Precipitation rainfall because at those discharge points, runoff discharges to areas owned by the Massachusetts Department of Conservation and Recreation(DCR) and is regulated by MassDEP and the Massachusetts Stormwater Policy. 5.2.2 Maximum Extent Practicable This report, in conjunction with the site plan set,provides documentation to demonstrate how this redevelopment project will retain stormwater on-site to the maximum extent practicable. • All reasonable efforts have been made to meet the applicable recharge requirements, as will be further described in the sections below. Page 7 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 • Several alternate stormwater measures were considered and evaluated for this redevelopment project, which proposes to implement stormwater BMPs recommended by the Massachusetts Stormwater Handbook for land uses with higher potential pollutant loads (LUHPPLs) including: o street sweeping; o catch basins with deep sumps and hooded outlets; 0 oil grit separators; and o subsurface infiltration systems. • The aforementioned techniques will be employed where feasible, and are designed in compliance with the Town of Watertown's Requirements for Stormwater Management and Erosion Control to the highest practicable level until the HVMA lease expires and a new subsurface infiltration system can be constructed on that parcel. The stormwater management system as designed will retain stormwater runoff volumes as summarized in Section 9.2 of this report. 5.2.3 Factors Affecting Retention Potential The site constraints listed below severely affect the proposed drainage system's ability to fully meet the 24-hour, 100-year, Cornell Extreme Precipitation rainfall recharge requirement: • Lack of Space: The site is located in a densely developed urban area or Watertown with a high land cost. Discharge from the site at Point of Analysis I is close to compliance under post-redevelopment conditions. Full compliance at this point would require a larger infiltration system footprint,which would result in significant loss of development value. This site is an example of the Town's desire to encourage density development conflicting with its goal of retaining all stormwater on-site. • Soils: SSI-I fully utilizes a Hydrologic Soil Group A (HSG-A) classification for the soils on the portion of the site that discharge to the Town of Watertown's drainage system. • Groundwater: SSI-1 fully utilizes the depth to estimated seasonal high groundwater. Four feet of separation is maintained between the bottom of system and estimated seasonal high groundwater since the system is utilized for peak rate attenuation. • Prior Contamination: Some subsurface exploration still has to be done,but no contamination has been encountered on-site to this point. • Underground Utilities: The presence of existing and proposed underground utilities notably reduces the amount of land available for on-site stormwater management controls. Utility corridors will be forced into certain locations due to the nature of the phased construction required because of certain tenant leases. In addition to utility corridors, three subsurface parking garages significantly reduce the land available for stormwater management. 5.2.4 Criteria for Determining Maximum Extent Practicable Section 8.4 of the Watertown Requirements for Stormwater Management and Erosion Control establishes the following criteria to determine if the 24-hour, 100-year, Cornell Extreme Precipitation rainfall retention standard has been met to the maximum extent practicable: • Factors affecting retention potential, as described in Section 5.2.3 of this report, have been identified on-site and preclude the ability to fully meet the retention standard. Page 8 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 o This criterion has been met; refer to Section 5.2.3 of this report. • Appropriate measures to reduce stormwater runoff from the site have been provided through better site design practices, such as removing extraneous parking, reconfiguring required parking, minimizing the use of impervious materials, and providing enhanced vegetation. o This criterion has been met; refer to the site plan set. • Appropriate measures have been taken to disconnect roof runoff from direct discharge to the drainage system. o This criterion has been met. Under post-redevelopment conditions, runoff from all building roofs will be directed to subsurface infiltration systems. Half of Building A will be directed to Subsurface Infiltration System I until the subsurface infiltration system on the HVMA parcel is built. The other half of Building A will continue along the existing drainage pattern to Point of Analysis 2 until the subsurface infiltration system on the HVMA parcel is built. Under future post- redevelopment conditions,when the subsurface infiltration system on the HVMA parcel is constructed, all of the buildings on the Mall lot and the HVMA lot will be directed to subsurface infiltration systems prior to discharge to the drainage system. • Appropriate measures have been taken to disconnect other existing paved areas from direct discharge to the drainage system, allowing controlled flow over pervious areas or through BMPs providing at least partial recharge. o This criterion has been met. The project incorporates publicly accessible landscaped open space between existing Building A and proposed Building F as a connection point to access adjacent public parkland. Additionally,under future post-redevelopment conditions, when the subsurface infiltration system on the HVMA parcel is constructed, runoff from all paved areas on the Mall lot and the HVMA lot will be directed to subsurface infiltration systems prior to discharge to the drainage system. • Appropriate measures have been taken to apply LID techniques for runoff reduction. Measures such as, but not limited to, porous pavement, green roofs, rain gardens, bioretention areas, and rainwater harvesting and reuse have been considered. o This criterion has been met; LID techniques have been evaluated for this site and applied to the maximum extent practicable,refer to Section 5.2.2 of this report. • There shall be a documented reduction in the rate and volume of runoff. In no instance shall there be an increase in the rate or volume of runoff from a redeveloped site. o This criterion has been met; refer to Section 9.2 of this report. • The design provides for treatment of all runoff from existing (as well as new) impervious areas to achieve the 80% TSS removal rate specified in the Massachusetts Stormwater Policy. o This criterion has been met; refer to Section 9.4 of this report. • All other elements of the Massachusetts Stormwater Policy are met. o This criterion has been met; refer to Section 4.0 of this report. 5.2.5 Documentation of Maximum Extent Practicable This report provides the following information illustrating that on-site stormwater management control measures have been provided to the maximum extent practicable: Page 9 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 • A description of the site-specific conditions that affect the ability to retain stormwater runoff. o This criterion has been met; refer to Section 5.2.3 of this report. • An alternatives analysis of all LID techniques and BMPs considered to reduce and manage stormwater runoff. o This criterion has been met; LID techniques have been evaluated for this site and applied to the maximum extent practicable, refer to Section 5.2.2 of this report. • Hydrologic and hydraulic estimates of stormwater runoff peak rates and total volumes from the site for the 2-, 10-, 25-, and 100-year design storms, demonstrating a documented reduction in the rate and volume of runoff. In no instance shall there be an increase in the rate or volume of runoff from a redeveloped site. A narrative explaining the degree to which stormwater runoff will be contained on-site shall accompany the estimates. o This criterion has been met; refer to Section 9.2 of this report. 5.2.6 Off-Site Work Section 8.6 of the Town of Watertown's Requirements for Stormwater Management and Erosion Control allows BMPs to be implemented at other locations,preferably within the same drainage area as the original redevelopment project, if all stormwater runoff cannot be retained on-site. Subsurface Infiltration System 1 is regulated by the Town of Watertown's Requirements for Stormwater Management and Erosion Control, and has been designed to hold and infiltrate the 24-hour, 25-year, Cornell Extreme Precipitation rainfall until the HVMA lease expires and a new subsurface infiltration system can be constructed on that parcel. When that future subsurface infiltration system is constructed to treat and control runoff associated with the HVMA parcel, Subsurface Infiltration System 1 (SSI-1) will reduce the peak flow rate of runoff discharged from the site at POA-1 by 95%. Since the proposed redevelopment project does not treat the full 24- hour, 100-year, Cornell Extreme Precipitation rainfall, a portion of the stormwater runoff from the Town's drainage system in Arsenal Street will be intercepted, routed through an oil grit separator, and directed to SSI-1 for infiltration. In storm events up to and including the 24-hour, 25-year, Cornell Extreme Precipitation rainfall, all of this runoff will be treated and completely infiltrated on-site. 5.2.7 Retention Waiver Section 8.7 of the Watertown Requirements for Stormwater Management and Erosion Control allows the retention requirement to be entirely waived in the following instances: • The site has been classified as contaminated; • Contamination has been capped in place; • An Activity and Use Limitation(AUL)precludes infiltrating runoff to the groundwater pursuant to Massachusetts General Law, Chapter 2 1 E and the Massachusetts Contingency Plan, 310 CMR 40; • The site contains a solid waste landfill as defined in 310 CMR 19; or • Groundwater from the recharge area flows directly towards a solid waste or 21 E site. Page 10 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 Subsurface exploration is still on-going on-site, but no contamination has been encountered to this point. Therefore, a"Retention Waiver" is not expected to be required to entirely waive the retention requirement. 6.0 Soil Data Soil data has been compiled using the Natural Resources Conservation Service (MRCS)Web Soil Survey located at URL: websoilsurvey.nres.usda.gov. The soil survey identified the soil on the majority of the site to be Urban Land with no Hydrologic Soil Group classification. The soil in the south portion of the site closest to the Charles River is identified by the survey as Udorthents with a wet substratum and no Hydrologic Soil Group classification (refer to Figure 2, "NRCS Web Soil Survey Map"). Borings and test pits were performed on-site by McPhail Associates, LLC. These explorations, as well as sieve analyses where the proposed subsurface infiltration systems will be located, classified the soils on-site according to the summary table below (refer to Appendix B for additional soils information): Subsurface USDA Soil Recommended Rawls Estimated Seasonal Infiltration System Classification Infiltration Rate High Groundwater (in/hr) Elevation SSI-1 (north) HSG-A, Sand 8.27 8.0 SSI-2 (south) HSG-B, Sandy Loam 1.02 4.0 SSI-3 (west, future) HSG-B, Sandy Loam 1.02 7.0 7.0 Hydrologic Methodology Existing and proposed drainage analyses were performed for the 2-, 10-, 25-, and 100-year storm events using HydroCAD version 10.00, which is based on the National Resources Conservation Service (NRCS), formerly the Soil Conservation Service (SCS) Technical Release 20 (TR-20) methodology for computing peak discharges from rainfall runoff for urban and rural watersheds. The 24-hour precipitation rates from the Town of Watertown DPW Site Plan Review On-Site Drainage Requirements were used in the analyses for the entire site. The 24-hour precipitation rates used for each storm event are as follows: Storm Event 24-Hour Precipitation (in) 2-Year 3.20 10-Year 4.90 25-Year 6.20 100-Year 8.90 The NRCS method uses several parameters based on watershed characteristics and configuration to generate a curvilinear unit hydrograph and produce a runoff hydrograph for the watershed. Page 11 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 Basic input data required to generate a hydrograph are the watershed area, storm frequency, time of concentration, 24-hour rainfall, and the watershed's runoff curve number. NRCS Technical Release 55 (TR-55)methodology was utilized to determine weighted runoff curve number(CN) for the existing and proposed watershed areas. Inputs for obtaining the weighted CN include ground cover type and the Hydrological Soil Group (HSG), as described in Section 6.0 of this report. Time of concentration (tc)was calculated based on the most hydrologically distant point (time-wise)within the watershed,but determined to be less than six minutes. A minimum time of concentration of six minutes was utilized for modeling purposes. Drainage catchment boundaries were established based on property lines, site topography, storm drainage layouts, and the major drainage exit points from the watershed, or Points of Analysis (POA). The pre-redevelopment watershed boundaries can be seen on Figure 6, "Pre- Redevelopment Watershed Plan", and the post-redevelopment boundaries can be seen on Figure 7, "Post-Redevelopment Watershed Plan". 8.0 Pre-Redevelopment Drainage Conditions 8.1 On-Site Resources There are no wetlands located on-site, but the Charles River is located within 100 feet of the site. Located on the south portion of the site are a 100-foot riverfront area setback, a 150-foot local buffer zone setback, and a 200-foot riverfront area setback associated with the Charles River. There will be no earth disturbance within the 100-foot riverfront area setback. The only earth disturbance to occur within the 150-foot local buffer zone setback will be associated with the construction of a pedestrian access stairway connecting the site to Greenough Boulevard. The only earth disturbance to occur within the 200-foot riverfront area setback, in addition to the pedestrian access stairway, will be the construction of proposed Subsurface Infiltration System 2. The site is located outside the 100-year flood zone according to Federal Emergency Management Agency(FEMA) FIRM panels 25017CO557E and 25017CO556E effective on 6/4/2010 (refer to Figure 3, "FEMA Flood Insurance Rate Map"). There are no endangered species habitats located within or near the site (refer to Figure 4, "Natural Heritage and Endangered Species Program Map"). No portion of the site is located within an Interim Wellhead Protection Area(IWPA), a Zone I Wellhead Protection Area, or a Zone II Wellhead Protection Area (refer to Figure 5, "Wellhead Protection Map"). 8.2 Pre-Redevelopment Hydrology The site was analyzed as five separate catchment areas flowing to four Points of Analysis (POAs)based on site topography, storm drainage layouts, and property lines. This site is unique in that its stormwater runoff is directed to two differently regulated areas. Runoff from the north and west portions of the site, and the adjacent HVMA parcel, discharges into the Town of Watertown's 30-inch storm drain in Arsenal Street(POA-1),which is regulated by the Town of Watertown's Requirements for Stormwater Management and Erosion Control. Runoff from the remaining east and south portions of the site is collected in one of three drain pipes owned by the Massachusetts Department of Conservation and Recreation (DCR), which all ultimately Page 12 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 discharge into the Charles River. As a state agency, the DCR is subject to the Massachusetts Stormwater Policy. Aside from catch basins, there are no existing water quality or infiltration measures anywhere on-site (refer to Figure 6, "Pre-Redevelopment Watershed Plan"). Watertown Stormwater Existing Catchment Area IA(EX-IA) This±7.35 acre catchment area makes up the northern portion of the site. Included in this catchment area are grass landscaped areas, building roofs, and paved parking areas. Stormwater runoff is collected in catch basins and roof drains,which discharge the untreated stormwater into the Town of Watertown's storm drain system in Arsenal Street(POA-1). Based on a letter prepared by Linenthal Eisenberg Anderson, Inc. Engineers (LEA), dated September 13, 1985, there are eight leaching catch basins were installed along the northern edge of the parking lot adjacent to Arsenal Street circa 1985 (refer to Appendix C for Letter prepared by LEA). These catch basins were designed in accordance with U.S. Weather Bureau Technical Paper No. 40 for a 10-year, 30-minute rainfall frequency producing 4.18 inches of precipitation and an initial 15-minute time of concentration. Four of the catch basins are interconnected by a 12-inch perforated vitrified clay overflow pipe connecting to the 30-inch drain pipe that leaves the site. These catch basins ultimately overflow into the Town of Watertown's storm drain system in Arsenal Street, and are accounted for in EX-IA. The remaining four leaching catch basins are not interconnected, and have no overflow pipe. In any rain storm exceeding 4.18 inches of precipitation, these four leaching catch basins will fill to capacity, flood out of the rim onto the parking lot, and overflow into the Town of Watertown's drainage system in Arsenal Street that does not connect to POA-1. The catchment area that drains to these four leaching catch basins has been excluded from this drainage analysis. Existing Catchment Area I (EX-lB) This±2.41 acre catchment area makes up the loading area for existing Building A and the adjacent HVMA parcel. Included in this catchment area are grass landscaped areas,building roofs, and paved parking areas. Stormwater runoff is collected in catch basins and roof drains, which discharge the untreated stormwater into the Town of Watertown's storm drain system in Arsenal Street(POA-1). DCR Stormwater Existing Catchment Area 2 (EX-2) This±4.57 acre catchment area makes up the southern portion of the site, and is mostly building roof area with small areas of paved access drives and grassed landscape areas. Stormwater runoff is collected in catch basins and roof drains that convey untreated stormwater through the DCR's 15-inch drain pipe south of existing Building A (POA-3). This runoff ultimately discharges into the Charles River. Existing Catchment Area 3A(EX-3A) This±2.32 acre catchment area makes up the eastern portion of the site. Included in this catchment area are grass landscaped areas, building roofs, and paved parking areas. Stormwater runoff is collected in catch basins and roof drains that convey untreated stormwater to the DCR's Page 13 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 24-inch drain pipe adjacent to Greenough Boulevard (POA-3A), which ultimately discharges into the Charles River. Home Depot Existing Catchment Area 3B (HDEX-3B) This f1.72 acre catchment area makes up a portion of the Home Depot parking area that will be intercepted by proposed Subsurface Infiltration System 2. Included in this catchment area are grass landscaped areas and paved parking areas. Stormwater runoff is collected in catch basins, flows through the DCR's 18-inch drain pipe adjacent to Greenough Boulevard(POA-213), and ultimately discharges into the Charles River. 8.3 Pre-Redevelopment Hydrological Conditions Below are summary tables of the pre-redevelopment peak flow rates and volumes of runoff at the Points of Analysis. As previously mentioned, the flows from POA-1 are regulated by the Town of Watertown's Requirements for Stormwater Management and Erosion Control, and the flows from POA-2 and POA-3 are regulated by the Massachusetts Stormwater Policy. Existing Peak Rates of Runoff in Cubic Feet per Second (cfs) Location Weighted Storm Event CN 2-Year 10-Year 25-Year 100-Year POA-1 92 25.88 42.57 55.20 81.16 POA-2 96 13.41 21.05 26.85 38.82 POA-31') 94 11.23 18.08 23.26 33.93 POA-3 combines flows from POA-3A(24-inch pipe) and POA-3B (I 8-inchpipe). Existing Runoff Volumes in Acre-Feet(ac-ft) Location Weighted Storm Event CN 2-Year 10-Year 25-Year 100-Year POA-1 92 1.932 3.268 4.304 6.475 POA-2 96 1.047 1.689 2.182 3.207 POA-V) 94 0.851 1.411 1.843 2.745 (')POA-3 combines flows from POA-3A(24-inch pipe) and POA-3B (I 8-inchpipe). Comprehensive hydrological computations for pre-redevelopment conditions are included in Appendix D. 9.0 Post-Redevelopment Drainage Conditions 9.1 Post-Redevelopment Hydrology Similar to existing drainage conditions, runoff from the north and west portions of the site will be directed to Point of Analysis 1 (POA-1) as regulated by the Town of Watertown's Requirements for Stormwater Management and Erosion Control, and runoff from the south and east portions of the site will be directed to Points of Analysis 2 and 3 (POA-2 and POA-3) as regulated by the Massachusetts Stormwater Policy. The installation of two subsurface infiltration systems and numerous drainage structures will result in significant improvements to the existing drainage conditions. Runoff from Proposed Catchment Areas I and 1B will be treated by oil Page 14 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 grit separators and directed to Subsurface Infiltration System 1. The proposed program will reduce the watershed area and amount of impervious area within Proposed Catchment Area 2, which results in a reduction of peak flow rates and volumes of runoff leaving the site at Point of Analysis 2. Additional drainage improvements will be implemented when the HVMA lease expires, and a new subsurface infiltration system can be constructed on that parcel. When that subsurface infiltration system is constructed, all of Proposed Catchment Area 2 will be directed to Subsurface Infiltration System 1, and there will be zero discharge from the site at Point of Analysis 2. Runoff from Proposed Catchment Areas 3A and 3B will be treated by oil grit separators and directed to Subsurface Infiltration System 2 (refer to Figure 7, "Post- Redevelopment Watershed Plan"). Watertown Stormwater The Town of Watertown's Requirements for Stormwater Management and Erosion Control state that"stormwater management systems must be designed such that all stormwater runoff is retained on-site to the Maximum Extent Practicable". Watertown's regulations also require that drainage analyses use 24-hour rainfall data from the web tool Extreme Precipitation in New York and New England as developed by the Northeast Regional Climate Center(NRCC) at Cornell University and the Natural Resources Conservation Service (MRCS). The 24-hour precipitation rates used for the analyses in accordance with Watertown's regulations can be found in the table in Section 7.0 of this report. These precipitation rates were used, not only for the areas of the site that discharge to the Town of Watertown's drainage system, but also to the DCR's drainage system. Proposed Catchment Area I(PR-IA) This±9.04 acre catchment area makes up the northern portion of the site and intercepts a portion of the Town's runoff from Arsenal Street to be treated on-site. Included in this catchment area are grass landscaped areas,building roofs, and paved parking areas. Stormwater runoff is collected in catch basins and roof drains and directed through oil grit separators to achieve 44% TSS removal prior to discharge to Subsurface Infiltration System 1 (SSI-1). SSI-1 has been designed in accordance with the Town of Watertown's Requirements for Stormwater Management and Erosion Control to the maximum extent practicable. SSI-1 will detain and infiltrate the 24-hour, 25-year, Cornell Extreme Precipitation rainfall under post-redevelopment conditions and future post-redevelopment conditions. An outlet control structure directs any overflow from the system during storm events larger than the 25-year Cornell Extreme Precipitation rainfall to the Town of Watertown's 30-inch storm drain in Arsenal Street(POA-1). Proposed Catchment Area I B (PR-1 B) This±2.67 acre catchment area makes up the loading area for existing Building A and the HVMA lot. It includes grass landscaped areas, building roofs, and paved parking areas. Stormwater runoff is collected in catch basins and roof drains and directed through oil grit separators to achieve 44% TSS removal prior to discharge to Subsurface Infiltration System 1 (SSI-1)under post-redevelopment conditions. This catchment area is being temporarily directed to SSI-1 until the HVMA lease expires and a new subsurface infiltration system can be constructed on the HVMA parcel to treat the runoff associated with that parcel. When the runoff from PR-1B is directed to the future HVMA subsurface infiltration system, SSI-1 will be sized to reduce the peak flow rate of runoff discharged from the site at Point of Analysis 1 (POA-1)by 95% and reduce the total runoff volume from the site at POA-1 by 97%. Page 15 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 DCR Stormwater The DCR is a state agency and as such, is subject to the Massachusetts Stormwater Policy. The Massachusetts Stormwater Policy requires that drainage analyses use 24-hour rainfall data as published by the Natural Resources Conservation Service (MRCS). Although significantly smaller precipitation rates could be utilized to design the drainage system flowing to DCR outlets, the larger Cornell extreme precipitation rates were used to design the drainage system for the entire site. As a redevelopment project, this work is subject to the Massachusetts Stormwater Policy to the maximum extent practicable. However, the on-site drainage system that directs stormwater runoff to the DCR system has been designed to fully comply with all the Stormwater Management Standards as if the site was previously undeveloped. It is anticipated that the parking lot will generate high-intensity-uses with over 1,000 vehicle trips per day, which would classify this project as a land use with higher potential pollutant load (LUHPPL). The stormwater management system has been designed so the water quality treatment train provides 80% TSS removal prior to discharge from the site and 44% TSS removal prior to discharge to Subsurface Infiltration System 2 (SSI-2). SSI-2 has been sized to reduce peak flow rates and volumes, and to treat the required water quality volume of 1-inch over the impervious area within the proposed watershed. Proposed Catchment Area 2 (PR-2) This±1.32 acre catchment area makes up the southern portion of the site, and will remain mostly building roof area with small areas of paved access drives and grass landscaped areas. Stormwater runoff is collected in catch basins and discharges to the DCR's 15-inch drain pipe at the south property line adjacent to the Watertown park land(POA-2). This catchment area, and the impervious area within, has been reduced under post-redevelopment conditions so that peak discharge rates and volumes are reduced compared to pre-redevelopment conditions in accordance with the Massachusetts Stormwater Policy. Under future post-redevelopment conditions, all of PR-2 will be directed to Subsurface Infiltration System 1, and there will be zero discharge from the site at POA-2. Proposed Catchment Area 3A(PR-3A) This±3.74 acre catchment area makes up the eastern portion of the site and a portion of the Home Depot parking area that will discharge to Subsurface Infiltration System 2 (SSI-2). Included in this catchment area are grass landscaped areas, building roofs, and paved parking areas. Stormwater runoff is collected in catch basins and roof drains and directed through an oil grit separator to achieve 44% TSS removal prior to discharge to SSI-2. SSI-2 has been designed in accordance with Massachusetts Stormwater Policy to treat and recharge 1-inch of runoff over the total impervious area within PR-3A and HDPR-3B and reduce peak discharge rates and volumes compared to pre-redevelopment conditions. Two outlet control structures will control and direct overflow from SSI-2 to the DCR's 24-inch drain pipe (POA-3A) and the 18-inch drain pipe (POA-3B) adjacent to Greenough Boulevard, both of which ultimately discharge into the Charles River. Home Depot Proposed Catchment Area 3B (HDPR-3B) This±1.54 acre catchment area consists of a portion of the Home Depot parking area that will discharge to proposed Subsurface Infiltration System 2 (SSI-2). Included in this catchment area Page 16 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 are grass landscaped areas and paved parking areas. Stormwater runoff is collected in catch basins and directed through an existing oil grit separator to achieve 44% TSS removal prior to discharge to SSI-2. SSI-2 has been designed in accordance with Massachusetts Stormwater Policy to treat and recharge 1-inch of runoff over the total impervious area within PR-3A and HDPR-3B, and reduce peak discharge rates and volumes compared to pre-redevelopment conditions. Two outlet control structures will control and direct overflow from SSI-2 to the DCR's 24-inch drain pipe (POA-3A) and the 18-inch drain pipe (POA-3B) adjacent to Greenough Boulevard, which discharge into the Charles River. 9.2 Post-Redevelopment Hydrological Conditions Under post-redevelopment conditions, two new subsurface infiltration systems will be constructed to detain and infiltrate runoff from the site. SSI-1 is designed in accordance with the Town of Watertown's Requirements for Stormwater Management and Erosion Control to the maximum extent practicable, and SSI-2 is designed in accordance with the Massachusetts Stormwater Policy. The tables below summarize how construction of these subsurface infiltration systems will result in reduced peak rates and volumes of runoff leaving the site at the Points of Analysis under post-redevelopment conditions compared to pre-redevelopment conditions. Point of Analysis 1 —Watertown Storm Drain System Pre- and Post-Redevelopment Peak Rates of Runoff in Cubic Feet per Second (cfs) Storm Existing Proposed Change % Flow Rate Flow Rate Frequency (cfs) (cfs) (cfs) Reduction 2-Year 25.88 0.00 -25.88 100% 10-Year 42.57 0.00 -42.57 100% 25-Year 55.20 0.00 -55.20 100% 100-Year 81.16 13.43 -67.73 83% Point of Analysis 1 —Watertown Storm Drain System Pre- and Post-Redevelopment Runoff Volumes in Acre-Feet (ac-ft) Storm Existing Proposed Change % Frequency Volume Volume (ac-ft) Reduction (ac-ft) (ac-ft) 2-Year 1.932 0.000 -1.932 100% 10-Year 3.268 0.000 -3.268 100% 25-Year 4.304 0.000 -4.304 100% 100-Year 6.475 0.559 -5.916 91% Page 17 Stormwater Report The Arsenal Project RIO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 Point of Analysis 2 —DCR Storm Drain System Roof Drainage—Half of Existing Building A Pre- and Post-Redevelopment Peak Rates of Runoff in Cubic Feet per Second (cfs) Storm Existing Proposed Change % Flow Rate Flow Rate Frequency (cfs) (cfs) (cfs) Reduction 2-Year 13.41 3.49 -9.92 74% 10-Year 21.05 5.76 -15.29 73% 25-Year 26.85 7.47 -19.38 72% 100-Year 38.82 11.00 -27.82 72% Point of Analysis 2 —DCR Storm Drain System Roof Drainage—Half of Existing Building A Pre- and Post-Redevelopment Runoff Volumes in Acre-Feet (ac-ft) Storm Existing Proposed Change % Frequency Volume Volume (ac-ft) Reduction (ac-ft) (ac-ft) 2-Year 1.047 0.259 -0.788 75% 10-Year 1.689 0.440 -1.249 74% 25-Year 2.182 0.581 -1.601 73% 100-Year 3.207 0.875 -2.332 73% Point of Analysis 3 —DCR Storm Drain System Combines flows from POA-3A (24"pipe) and POA-3B (18"pipe) Pre- and Post-Redevelopment Peak Rates of Runoff in Cubic Feet per Second (cfs) Storm Existing Proposed Change % Flow Rate Flow Rate Frequency (cfs) (cfs) (cfs) Reduction 2-Year 11.23 0.51 -10.72 95% 10-Year 18.08 6.69 -11.39 63% 25-Year 23.26 12.74 -10.52 45% 100-Year 33.93 21.26 -12.67 37% Point of Analysis 3 —DCR Storm Drain System Combines flows from POA-3A (24"pipe) and POA-3B (18"pipe) Pre- and Post-Redevelopment Runoff Volumes in Acre-Feet (ac-ft) Storm Existing Proposed Change % Frequency Volume Volume (ac-ft) Reduction (ac-ft) (ac-ft) 2-Year 0.851 0.101 -0.750 88% 10-Year 1.411 0.681 -0.730 52% 25-Year 1.843 1.158 -0.685 37% 100-Year 2.745 2.208 -0.537 20% Comprehensive hydrological computations for post-redevelopment conditions are included in Appendix D. Page 18 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 Future Post-Redevelopment Hydrological Conditions After Construction of the Subsurface Infiltration System on the HVMA Parcel Future Point of Analysis 1 —Watertown Storm Drain System Pre- and Post-Redevelopment Peak Rates of Runoff in Cubic Feet per Second (cfs) Storm Existing Proposed Change % Flow Rate Flow Rate Frequency (cfs) (cfs) (cfs) Reduction 2-Year 25.88 0.00 -25.88 100% 10-Year 42.57 0.00 -42.57 100% 25-Year 55.20 0.00 -55.20 100% 100-Year 81.16 4.28 -76.88 95% Future Point of Analysis 1 —Watertown Storm Drain System Pre- and Post-Redevelopment Runoff Volumes in Acre-Feet (ac-ft) Storm Existing Proposed Change % Frequency Volume Volume (ac-ft) Reduction (ac-ft) (ac-ft) 2-Year 1.932 0.000 -1.932 100% 10-Year 3.268 0.000 -3.268 100% 25-Year 4.304 0.000 -4.304 100% 100-Year 6.475 0.168 -6.307 97% Future Point of Analysis 2—DCR Storm Drain System Zero Discharge from Site Pre- and Post-Redevelopment Peak Rates of Runoff in Cubic Feet per Second (cfs) Storm Existing Proposed Change % Flow Rate Flow Rate Frequency (cfs) (cfs) (cfs) Reduction 2-Year 13.41 0.00 -13.41 100% 10-Year 21.05 0.00 -21.05 100% 25-Year 26.85 0.00 -26.85 100% 100-Year 38.82 0.00 -38.82 100% Future Point of Analysis 2—DCR Storm Drain System Zero Discharge from Site Pre- and Post-Redevelopment Runoff Volumes in Acre-Feet (ac-ft) Storm Existing Proposed Change % Frequency Volume Volume (ac-ft) Reduction (ac-ft) (ac-ft) 2-Year 1.047 0.000 -1.047 100% 10-Year 1.689 0.000 -1.689 100% 25-Year 2.182 0.000 -2.182 100% 100-Year 3.207 0.000 -3.207 100% Page 19 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 Future Point of Analysis 3 —DCR Storm Drain System Combines flows from POA-3A(24"pipe) and POA-3B (18"pipe) Pre- and Post-Redevelopment Peak Rates of Runoff in Cubic Feet per Second (cfs) Storm Existing Proposed Change % Flow Rate Flow Rate Frequency (cfs) (cfs) (cfs) Reduction 2-Year 11.23 0.51 -10.72 95% 10-Year 18.08 6.69 -11.39 63% 25-Year 23.26 12.74 -10.52 45% 100-Year 33.93 21.26 -12.67 37% Future Point of Analysis 3 —DCR Storm Drain System Combines flows from POA-3A (24"pipe) and POA-3B (18"pipe) Pre- and Post-Redevelopment Runoff Volumes in Acre-Feet (ac-ft) Storm Existing Proposed Change % Frequency Volume Volume (ac-ft) Reduction (ac-ft) (ac-ft) 2-Year 0.851 0.101 -0.750 88% 10-Year 1.411 0.681 -0.730 52% 25-Year 1.843 1.158 -0.685 37% 100-Year 2.745 2.208 -0.537 20% Comprehensive hydrological computations for future post-redevelopment conditions are included in Appendix D. 9.3 Groundwater Recharge Because the amount of landscaped/open area is increased by approximately 13,000 square feet under post-redevelopment conditions, the annual recharge of groundwater will be increased compared to pre-redevelopment conditions. Furthermore,because the Town of Watertown's Requirements for Stormwater Management and Erosion Control require all stormwater runoff to be retained on-site to the maximum extent practicable, the installation of the proposed subsurface infiltration systems will provide additional storage to significantly increase the amount of annual groundwater recharge on-site compared to pre-redevelopment conditions. Groundwater Recharge Provided: Subsurface Estimated Recommended Rawls Total Recharge Infiltration Elevation Seasonal High Infiltration Rate Volume Provided System Groundwater (in/hr) (cf) SSI-1 (north) 12.0—25.0 8.0 8.27 (Sand) 129,080 SSI-2 (south) 8.0— l 4.0 4.0 1.02 (Sandy Loam) 56,365 Total Volume Provided 185,445 Page 20 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 Daawdown Time The Massachusetts Stormwater Policy states that the minimum required recharge volume should infiltrate within 72 hours. The drawdown analysis is performed by dividing the storage volume of the infiltration system by the product of the recommended Rawls infiltration rate of the existing soils beneath the system and the bottom area of the system. R„ T lmedrawdown — (K)(Bottom Area) Where: Rv=Recharge BMP Storage Volume K=Recommended Rawls Infiltration Rate Bottom Area=Bottom Area of Recharge BMP Subsurface Infiltration Svstem 1 129,080 cf T imedrawdown = = 12.8 hours (8.2 7 lnlhr) 1 f t112 in (66.0 f t)(222.0 f t) Subsurface Infiltration Svstem 2 56,365 cf Timedrawdown = = 47.0 hours (1.02 in1hr) 1 f t/12 in (44.5 f t)(317.0 f t) 9.4 Stormwater Quality As a land use with higher potential pollutant load(LUHPPL), the site is required to provide 44% Total Suspended Solids (TSS)removal prior to discharge to the infiltration BMP and 80% TSS removal from new impervious areas prior to discharge from the site. The water quality volume from the redeveloped site will undergo treatment to the maximum extent practicable through the use of structural and non-structural Best Management Practices (BMPs). Runoff from paved surface parking lot areas will be pre-treated to remove 44% of the TSS prior to infiltration in the subsurface systems in accordance with the Massachusetts Stormwater Policy. The following BMP's were selected to remove 80% of the average annual post-construction load of TSS from stormwater runoff. • Street Sweeniniz Sweeping will be performed routinely, at least monthly, within the parking lot and driveway areas to reduce sediments and trash before they can enter the catch basins. Refer to Appendix E for performance data. • Catch Basins with Deen Sumps and Hooded Outlets Stormwater runoff from pavement areas will be directed via curbing and site grading to catch basins with deep sumps and hooded outlets. Catch basins trap and remove sediments and larger particles from stormwater runoff and improve the performance of subsequent BMP's. The catch basin sumps will be a minimum of 4 feet in depth, and a Page 21 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 regular inspection and cleaning schedule will be followed to ensure optimal effectiveness. When properly constructed and maintained, catch basins with deep sumps and hooded outlets are effective in reducing the sediment and pollutant load in runoff. Refer to Appendix E for performance data. • Oil Grit Separators Oil grit separators are precast concrete structures designed to remove settleable solids and floating contaminants from stormwater runoff. Although it varies by manufacturer, they are typically designed to remove at least 25% TSS for the 1-inch water quality flow. Low storm flows are directed into a treatment chamber where floatables and neutrally buoyant debris are trapped and settleable solids sink to the sump of the structure. Larger flows are controlled by an internal diversion weir, which directs high intensity storm events around the treatment chamber to the drainage system does not backwater. Runoff from paved surface parking areas will be routed through oil grit separators prior to discharge into SSI-1 and SSI-2. Refer to Appendix E for performance data. • Subsurface Infiltration Svstems Stormwater runoff will be directed into two subsurface infiltration systems after being pre-treated by catch basins with deep sumps and hooded outlets and oil grit separators. SSI-1 has been designed to detain and infiltrate runoff from the 24-hour, 25-year, Cornell Extreme Precipitation rainfall. When the new HVMA subsurface infiltration system is constructed, SSI-1 will reduce the peak flow rate of runoff discharged from the site at Point of Analysis 1 (POA-1)by 95% and reduce the total runoff volume from the site at POA-1 by 97%. SSI-2 has been designed to detain and infiltrate more than 1-inch of runoff over the total impervious area within its post-redevelopment watershed, as well as reduce peak rates and volumes of runoff discharging from the site compared to pre- redevelopment conditions. Refer to Appendix E for performance data. TSS Removal Calculation Worksheet Table BMP TSS Removal Starting Amount Removed Remaining (A) Rate TSS Load (BxC) Load (C-D) (B) (C) (D) (E) Street Sweeping 0.05 1.00 0.05 0.95 Catch Basins with Deep Sumps and 0.25 0.95 0.24 0.71 Hooded Outlets Oil Grit Separators 0.25 0.71 0.18 0.53 Subsurface 0.80 0.53 0.42 0.11 Infiltration Systems Total TSS Removal= Summation of(D)= 89% 10.0 Summary The proposed stormwater management system for the redevelopment includes measures for collecting, controlling, and treating stormwater runoff from the site. The drainage improvements proposed herein will reduce stormwater runoff peak flow rates and volumes leaving the site, increase groundwater recharge, and improve storm runoff water quality. The proposed measures under the redeveloped conditions comply with the Massachusetts Stormwater Handbook and the Page 22 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown. MA 02472 Town of Watertown's Requirements for Stormwater Management and Erosion Control to the maximum extent practicable, and represent a significant improvement over pre-redevelopment conditions. The proposed modifications include the following improvements: 10.1 Stormwater Management System Design The proposed stormwater management system has been designed to significantly reduce peak discharge rates and volumes at three Points of Analysis (POA). Under post-redevelopment conditions, two new subsurface infiltration systems will be initially constructed, and a third subsurface infiltration system will be constructed on the Harvard Vanguard Medical Associates (HVMA)parcel in the future. These subsurface infiltration systems will result in reduced peak rates and volumes of runoff leaving the site at the Points of Analysis under post-redevelopment conditions compared to pre-redevelopment conditions as summarized below. Point of Analysis I (POA-1)—30"Drain Line Subsurface Infiltration System 1 (SSI-1), which is located at the north side of the site, will discharge to the Town of Watertown's existing 30-inch drain line in Arsenal Street. SSI-1 will initially provide an 83% reduction of the peak flow rate, and a 91% reduction of the total runoff volume for the 24-hour, 100-year rainfall rate from the Extreme Precipitation in New York and New England developed by the Northeast Regional Climate Center at Cornell University, often referred to as the Cornell rate. After construction of the new subsurface infiltration system on the HVMA parcel, SSI-1 will provide a 95%reduction of the peak flow rate, and a 97%reduction of the total runoff volume for the 24-hour, 100-year, Cornell rainfall accumulation. Point of Analysis 2 (POA-2)— 15"Drain Line The area and runoff curve number of the watershed that discharges runoff to Point of Analysis 2 (POA-2), which is located on the south side of the site, will be reduced under post- redevelopment conditions. These reductions will initially provide a 72%reduction of the peak flow rate, and a 73%reduction of the total runoff volume for the 24-hour, 100-year, Cornell rainfall accumulation. After construction of the new subsurface infiltration system on the HVMA parcel, all of the runoff from the watershed will discharge to either SSI-1 or the new HVMA system. Ultimately, no runoff will be discharged from the site at POA-2, resulting in a 100% reduction in both the peak flow rate and the total runoff volume for the 24-hour, 100-year, Cornell rainfall accumulation. Point of Analysis 3 (POA-3)—24" & 18"Drain Lines Subsurface Infiltration System 2 (SSI-2), located at the southeast portion of the site, will discharge to the Massachusetts Department of Conservation and Recreation(DCR) drainage system in Greenough Boulevard. SSI-2 has been designed to detain and infiltrate approximately 88% of the volume for the 24-hour, 2-year, Cornell rainfall accumulation of 3.2 inches. This system exceeds the 1-inch water quality volume requirement, and will significantly reduce post- redevelopment peak flow rates and volumes compared to pre-redevelopment rates and volumes at POA-3. Page 23 Stormwater Report The Arsenal Project RJO'CONNELL & ASSOCIATES. INC. Watertown, MA 02472 10.2 Water Quality The water quality of the site will be greatly improved under post-redevelopment conditions. Stormwater best management practices (BMPs) to be implemented on-site include: street sweeping, catch basins with deep sumps and hooded outlets, CDS oil/particle separators, and subsurface infiltration systems. The average annual post-construction load of total suspended solids (TSS)removed by this BMP process train, which applies to Points of Analysis 1 and 3, is 89%. Based upon the P8 Water Quality Model performed for the Final Phosphorus Total Maximum Daily Load(TMDL) Report for the Charles River Basin, infiltration practices sized to store and infiltrate 1.0-inch of runoff from impervious cover captures at least 80% of the phosphorus in the runoff. Infiltration practices designed to this standard significantly exceed the 65%requirement by which Watertown is required to reduce their annual phosphorus loading to the Charles River. On this site, more than 95% of the phosphorus loading in the runoff will be captured at all three Points of Analysis, where infiltration practices have been sized to store and infiltrate at least 2.8 inches. Most of the parking will be provided in subsurface and above- ground garages, which will be protected from exposure to rain, snow, snowmelt, and stormwater runoff, significantly reducing the potential pollutant load in stormwater runoff on the site. 10.3 Operation and Maintenance Plan An Operation and Maintenance Plan(O&M) is provided as part of the attached Stormwater Report to ensure that the proposed improvements and treatment measures are effective after the completion of construction activities. Page 24 II. FIGURES �zoo" a ec^0 3 r- .oF«evUF N �1Nh►tney h Q ° \�Mpg nt ? Moon` wake il' H m Q w Auburn old Aub rn�J� . .� o CO011fl e'Hl Burying Place Gem ,El v���F` �Q ,MT-AUBURN-ST 1 East ))'1- I , 'B• .- :DGE 0: vVATtn Watertown r T ��� 7,rvi. +Cem� ' ' ER '�C♦ '0 � SQL Common ��� t sA'' Coolidge SG�"� Street so < H►(( , �Oti C�., Cem 9�2 $ PUTNAM ST Aa �eQ T S NE SPRUCE ST P, _ tiCNE R,�R 5� ARSEN L ST CYPRESS ST Sawitts /— CpNST Pond \ 0 C Q / WESTERN AVE— N \ �U sp Site / a Z NO RL SRtJRRR° ♦\\ % /, ` LY �Q ST r WAVER TU"'-Rom N NANTUM RD- / 40 M BIRMING P � North Brightor. L/NCOL ST HUNNEWFLC 4VE Tf °a ST / GUEST ST '1 ENE �iCF< NEU/L ST b —�Qsy� sr o �'• �GpN ST t GARDN! tiG�c t A��N \. 10o Earie ANEUIL ST AIIJ T ��� 20 BR/GH7 RL pNA-� 'SST C�°NST ►\ f —- � `�� ♦PF�O � 'y Market tree) J h E A N° RD \ Bufv n Grounder .FFE ASHING`T/ON�SyTjJ kARRE LEaJ�� f 30 °��200 G150� rightOn p /� C }/r Stro gs� Clzandler, t A i�I� Q ¢/G \o a zoo Po" d Pond���RDa w � �� yo JohnsSe 4 ALG NQL/N. j AVE Weston uit �� °i C,r and Q VYaban v Sch of T'ology Z �� J - 3 t �` v _cy/S MYTH / Boston�G�a u� ch EON'S I II111(lw ) 30 �I WICK Newton ervoir J t 1 IX I 90 ��—" of Psych analy s 'l\ Q� gpCISBURY RD t l 10C I .,Evergreen Cem 250_Boston_C ll ( t� � MON` � � \\I t C estnut Hill Aspinwall eservoir Hlt( BEACON ST ool °� Beacons eld 7o Qo y�°Rpa.R�t061 °v 9 6hestnut Newbury eo° RD 4VS !r �Q Hill Ir 1 r t ollege-Brookline 1n ti.tuLl In ` 2,000 0 1,000 2,000 4,000 � OJ o pG �j Fpt Ve ton �1 1OD ,at h/ �(�II11111 ammond>� ;/ GRAPHIC SCALE IN FEET Prepared M O'CONNELL s by' ♦ Project Name Drawing Name: , Drawing No Drown by B Designed by: S R 1 J THE ARSENAL USGS SITE FAG-1 Checked by: 5PG/Rws &ASSOCIATES,INC. r `" Scale: 1"=2,000' °`°°"' PROJECT LOCUS MAP 1 D°te 07/11/2016 WATERTOWN,MA Project No. 16041 No FUSION 0.4iE Copyright©2016 by R J.0"Conn01&Associates.Inc Drawing name: G\MA\Watertown\Boylston Properties\Arsenal Mall\Reports\Storm water Report\Figures\1 6041—FIG—1 USGS Map.dwg Jun 23, 2016 — 17.06pm N / \ .6 P t LT da II o c � T _-- _— S Designed by: JJS • �* �� — — Drawn by: SMS + Checked by: SPG/RWS Scale: 1"=250' r Date: 07/1 1/2016 Au Prepared FO,_ tir PA P. ,' THE WILDER COMPANIES �l 800 BOYLSTON STREET,SUITE 1300 '■I _ 61]-4 PHONE BOSTON,MA 02199 ■ 27-9200 �.� AND 6W (; ` . BOYLSTON PROPERTIES L'J — • 47T 800 BOYLSTON STREET,SUITE 1390 PHOTON,MA 02199 r ` PHONE 61]-262-46-4646JL / a Prepared By: RJO'CONNELL &AssocuTiFs,INC. ® �_ r E CIVIL ENGINEERS, SURVEYORS B D PLANNERS O 80 MONTVALE AVE STONEHAM,MA 02180 * + _ PHONE ]81-2]9-0180 FAX 181-2]9-01]3 LZ rn 11.1 1 w / \ o Project Name: o' �•wi w THE ARSENAL u PROJECT 0 WATERTOWK MA 0 o Drawing Name: HYDROLOGIC SOIL GROUP - _•�-' - ' � f �� � NRCS WEB ��SNIT _- -.._` _ }� ,r It SOIL SURVEY MAR UNIT NAME RATING r MAP SYMBOLED I WATER 602 URBANLAND _ �! _ ` Drawing No.: ao 603 URBANLAND, WET SUBSTRATUM Y 250 0 125 250 500 FIG-2 4;0 653 UDORTHENTS,SAND' E N ���illillill I INS III 655 UDORTHENTS, WET / �¢ Project No.: 16041 o SUBSTRATUM / GRAPHIC SCALE IN FEET CoPY,;9h<©2D,6 by R J.OConnell&Associates, -'•,f^ I- -+ INS - as --'�� � rr r —4 IR lly- AT / \ y r r. F Designed by: JJS � • ! � i- Drawn by: BMS Checked by: SPG/RWS Scale: 1 IINF1_ Date: 07/11/2016 FT- �_ / \ r �� . �. Prepared For: :F 1V wlab THE ' •1 * ■ r WILDER O I ES 800 BOYLSTON STREET,,SUITE 1300 :. k K I y� _ r - ,� BOSTON,MA 02199 -�1_ RR ■.� ! PHONE 61]-42]-9200 AND 4 ■■��[xy , t Bon,n 1oNFRaFERT[FS is I BOYLSTON PROPERTIES 800 BO,MA 0 STREET,SUITE 1390 BOSTOPHONE ,MA 0-46 pop- ` 2199 PHONE 61]-262-4646 / Prepared By: LU M I RJC) CONNELL &ASSOCIATES,INC. t. CIVIL ENGINEERS,SURVEYORS �I &LAND PLANNERS r L AVE STONEHAM,MA02180 PHONE ]81-2]9-0180 +++••••••��� FAX 781-2]9-01]3 LZ I a ` Project Name: ° THE ARSENAL PROJECT ° WATERTOWN,MA y , 1, �.. •�■I� ~ Drawing Name: FEMA FLOOD a Flood Hazard Zones INSURANCE 1% Annual Chance Flood Hazard - RATE MAP 3 Regulatory FloodwayJL c Special Floodway ' +'i Drawing No.: Area of Undetermined Flood Hazard 6� 0.2% Annual Chance Flood Hazard 250 0 125 250 500 FIG 3 Future Conditions 1% Annual Chance Flood Hazard rnN . Project No.:o 16041 Area with Reduced Risk Due to Levee � / GRAPHIC SCALE IN FEET °o,Y.;9ht©2016 by RJ.OConnell&Associates, AP9 do, * .. TF +err f do p Ilk 46 f ■ veA • - - .• . Adk— iF �iJ1 a� _ •' _ %4W qp " jr a _ _ • ■ w ifs • is46� i f ' + If ;• r • a is yj • -Ilk a * ..'• -61 *,�*+ • A dr .. 49 • O it 9 _ # dop #• �F • • • o d f • • M- * 1 Y t ,,� r * • • �4 • • • di 0 All YEW do milli • * F ., Y f Z- 0 i LEGEND EX-IA TO POA-I: WATERTOWN STORMWATER o01 EX-1B TO POA-I: WATERTOWN STORMWATER EX-2 TO POA-2: DCR STORMWATER EX-3A TO POA-3A: DCR STORMWATER Designed by: JJS �. Drawn by: BMS Checked by: SPG/RWS HDEX-3B TO POA-3B: DCR STORMWATER Scale: 1"=150' ' Date: 07/11/2016 POINT OF ANALYSIS#3 - -. -, DCR STORMWATER .� _�, _ _-,� _ -.,�--,,:��-,,,..� NOTE: THE TIME OF CONCENTRATION HAS BEEN / COMBINES POA#3A(24"PIPE) - ``"-" '" CALCULATED TO BE LESS THAN 6 MINUTES. A MINIMUM / AND POA#3B(18"PIPE) TIME OF CONCENTRATION OF 6 MINUTES HAS BEEN Prepared Fc, Q2(3.2IN)=11.23 CFS=0.851 AF UTILIZED FOR MODELING PURPOSES. Q10(4.9 IN)=18.08 CFS=1.411 AF Q25(6.2 IN)=23.26 CFS=1.843 AF Q100(8.9 IN)=33.93 CFS=2.745 AF _ • „�� -71 POINT OF ANALYSIS#2-15"PIPE DCR STORMWATER THE WILDER COMPANIES 0 STREET,SUITE 1300Q2(3.2 IN)=13.41 CFS=1.047 AF BOSTONMA21 ('Io(4.9 IN)=21.05 CFS=1.689 AF PHONE 617-427-9200 Q25(6.2 IN)=26.85 CFS=2.182 AF AND rn - - i aoa(8.9 IN)=38.82 CFS=3.207 AF �u C y I I I I I (I l � �T l l l I � • H D EX-3B 'BOYLSILZN PROPI RTIES ea TOTAL AREA=74,949 SF(1.72 AC) BovLsroN PROPERTIES C® 800 BOYLSTON STREET,SUITE 1390 �" IMP.AREA=69,766 SF(1.60 AC) - BOSTON,MA 02199 E • / CN= PHONE 617-262-4646 / CI Prepared By: -- �) TOTAL AREA= SFC) a` -- " IMP.AREA 186,276 (4.28 AC) - �� _ II Id I�lid°1 _ RJO�CONNELL CN=96 &ASSOCIATES,INC. (9 - I I' ✓- CIVIL ENGINEERS,SURVEYORS L BLAND PLANNERS L/ �I __ �� n .. _ L - u I L II 60 MONT NEHAM,M AVE -- EX-3A 4 �- - EX-1B -- PHONE MA 02160 N -- -- PHONE ]812]9-0180 ��17A TOTAL AREA=101,042 SF(2.32 AC) _ U-� TOTAL AREA=105,011 SF(2.41 AC) x FAX ]81-2]9-01]3 IMP.AREA=88,174 SF(2.02 AC) �� IMP.AREA=81,250 SF(1.87 AC)4 L CN=93 00 L CN-90 w i a .A � ,• p � �y � � __- Project Name: �� THE ARSENAL �» EX; oo a PROJECT OTAL AREA CN20932 SF (7.35 AC) 0 A_� WATERTOWK MA IMP.AREA-290,979 SF 6 68 AC .�p1 1 y ! Drawing Name: 0 0 o - - PRE- - - REDEVELOPMENT � . y #1-30'PIPE WATERSHED PLAN POINT OF ANALYSIS ED WATERTOWN STORMWATER 3 Q2(3.2 IN)=25.88 CFS=1.932 AF '"'50'14C - S7REEr ARS&W -<• sn�r ` o Q10(4.9 IN)=42.57 CFS=3.268 AF = "" / o° Q25(6.2 IN)=55.20 CFS=4.304 AF Drawing No.: Qiao(8.9 IN)=81.16 CFS=6.475AF FIG-6 �l 150 0 75 150 300 N mN ` Project No.: 16041 o; GRAPHIC SCALE IN FEET Copyright©2016 by R J.O'Connell&Associates.Inc LEGEND \ PR-lA TO POA-I: WATERTOWN STORMWATER 00f x PR-113 TO POA-1: WATERTOWN STORMWATER PR-2 TO POA-2: DCR STORMWATER PR-3A TO POA-3: DCR STORMWATER Designed by: JJS Drawn by: BMS Checked by: SPG/RWS HDPR-3B TO POA-3: DCR STORMWATER Scale: 1"=150' _ Date: 07/1 1/2016 POINT OF ANALYSIS#3 C DCR STORMWATER _ NOTE: THE TIME OF CONCENTRATION HAS BEEN \ / �,._-�. ;w �.� �-� _.� ,.��-Z.--°'' COMBINES POA#3A(24"PIPE) CALCULATED TO BE LESS THAN 6 MINUTES. A MINIMUM / \ AND POA#313(18"PIPE) TIME OF CONCENTRATION OF 6 MINUTES HAS BEEN Prepared Fo ->- ' Q2(3.2 IN)=0.51 CFS=0.101 AF UTILIZED FOR MODELING PURPOSES. Q10(4.9 IN)=6.69 CFS=0.681 AF Q25(6.2 IN)=12.74 CFS=1.158 AF Q100(8.9 IN)=21.26 CFS=2.208 AF _ _ _ _ _ _ _ - • '� ��j a POINT OF ANALYSIS#2-15"PIPE i / i �OVGH BOLt�VARD - - ET.SUITE 1300 _ = PHONE ,M - ,,,.��"- DCR STORMWATER THE WILDER COMPANIES _ Q2(3.2 IN) 49 CFS 0.259 AF eosrori BOYLSTON oz199 �- ----- ---- " Q1o(4.91N) 576 CFS O440 AF 4279200 > - -Q25(6.2 IN)=7.47 CFS=0.581 AF AND _ _ Q1oa(8.9 IN) 11.00 CFS 0.875 AF i I ® / / . TOTAL AREA=57,681 SF(1.32 AC) BOYLg1LZN PROPERTIES IMP.AREA=48,060 SF(1.10 AC) BOYLSTON PROPERTIES ✓`P% / /� ♦••o / _ CN=92 800 BOYLSTON STREET,SUITE 1390 BOSTON,MA 02199 a % % HDPR-3B -� / I ®, - ] PHONE 617-262-4646 / ° e r TOTAL AREA=66,885 SF(1.54 AC) m { IMP.AREA=58,746 SF(1.35 AC) CN-93 Prepared By: RJO'C ONNELL - �k-1 B &ASSOCIATES,INC. Pr0A o ' - - ( ) Y �- _ -r - - -� -j7 4 TOTAL AREA=116,176 SF(2.67 AC) 1 CIVIL ENGINEERS,SURVEYORS _ I 'yfll-J11 TOTAL AREA 162,941 SF 3.74 AC r IMP.AREA 157,382 SF(3.61 AC) MP.AREA=91,850 SF(2.11 AC) 8 LAND PLANNERS CN-97 J -� 80 MONTVALE AVE 1 CN- I STONEH AM MA 02180 --- b PHONE '-2 -017380 I: v. 1 -li II f �� I FAX ]81-2]9-01]8 I I , ® ® ®Z ® Ir _ 1 ro1ec P t Name I 1, I � I a - AroRroe�_�_ -.,:Y. - ens rn 3 ` - THE ARSENA L I � I PR-iA � IPA � = � PROJECT )TAL AREA=393,607 SF(9.04 AC) �� - WATERTOWN,MA I VIP.AREA=380,724 SF(8.74 AC) o - g CN=96 u I a I > Drawing Name: N g POST- a a REDEVELOPMENT - - -- - -- --' _ _ f _ T- - - -------- WATERSHED PLAN aes STREET A POINT OF ANALYSIS#1-30"PIPE / ED ""`- "°� WATERTOWN STORMWATER "sue w;Tn cT I i i Q2(3.2 IN)=0.00 CFS=0.000 AF _ 0 010(4.9 IN)=0.00 CFS=0.000 AF - � _ - s - Drawing No.: \ a QY5(6.2 IN)=0.00 CFS=0.000 AF Q100(8.9 IN)=13.43 CFS=0.559 AF FIG-7 w l 150 0 75 150 300 EN Project No.: 16041 / GRAPHIC SCALE IN FEET Copyright©2016 by R J.O'Connell&Associates.Inc LEGEND \ PR-1A TO POA-I: WATERTOWN STORMWATER 00f x PR-113 TO POA-1: WATERTOWN STORMWATER PR-2 TO POA-1: WATERTOWN STORMWATER PR-3A TO POA-3: DCR STORMWATER Designed by: JJS Drawn by: BMS Checked by: SPG/RWS HDPR-3B TO POA-3: DCR STORMWATER Scale: 1"=150' _ Date: 07/1 1/2016 POINT OF ANALYSIS#3 C DCR STORMWATER _ NOTE: THE TIME OF CONCENTRATION HAS BEEN \ / �. ;- �.� �� _.� ,.�•�-Z.--°'' COMBINES POA#3A(24"PIPE) CALCULATED TO BE LESS THAN 6 MINUTES. A MINIMUM / \ AND POA#313(18"PIPE) TIME OF CONCENTRATION OF 6 MINUTES HAS BEEN Prepared Fo - Q2(3.2 IN)=0.51 CFS=0.101 AF UTILIZED FOR MODELING PURPOSES. Q10(4.9 IN)=6.69 CFS=0.681 AF Q25(6.2 IN)=12.74 CFS=1.158 AF Q100(8.9 IN)=21.26 CFS=2.208 AF " _ _ _ _ _ _ _ - • '� ��j a POINT OF ANALYSIS#2-15"PIPE - - / _ _ _.��"-"°°�• DCR STORMWATER THE WILDER coMPnNles H gpLt�VAgO PHONE ,MA2 2199 STREET,SUITE 1300 ,No i - _ _ _ _ _ - Q2(3.2 IN)=0.00 CFS=0.000 AF 800 TON,MA BOYLSTON Q10(4.9 1N)=O.00 CFS=0.000 AF Q25(6.2 IN)=0.00 CFS=0.000 AF AND _ _ Q100(8.9 IN) 0.00 CFS 0.000 AF e / ® / ..�.... - TOTAL AREA=57,681 SF(1.32 AC) } BOYLg1LZN PROPERTIES _ -- IMP.AREA=48,060 SF(1.10 AC) {{ { ggpp t BOYLSTON PROPERTIES 800 BOYLSTON STREET,SUITE 1390 �� - CN=92 BOSTON,MA 02199 I _ a / / HDPR-3B e -� I ! -- a xio�' PHONE 6 -262-4646 / m r TOTAL AREA=66,885 SF(1.54 AC) �'' _ f n � IMP.AREA=58,746 SF(1.35 AC) � CN 93 o / / _ In m � - i I )� � Prepared By: 10 RJO'CONNELL - = " III " �R-1 B $�1�6SOCIATES,S - pR-3A �- - _ TOTAL AREA=155,841 SF(3.58 AC) 1 CIVIL ENGINEERS,SURVEYORS lY IMP.AREA-157,382 SF(3.61 AC) - ;; ___ -- IMP.AREA=128,253 SF(2.94 AC) &LAND PLANNERS • TOTAL AREA-162,941 SF(3.74 AC) I I �z I 80 MONTVALE AVE CN=97 Y _- - _ _ �° _ I CN=91 STONEHAM MA 02180 PHO E ]81 2]9 01 3 r - N 80 II'I � m ) _ - / - I - II �. ....._ _ � _ I9 t a LZ � 01 Project Name: P��Eo THE ARSENAL .. �ILoIR.� �� c P R 1 A "�x� r��� o I, E - i N ,I > - ° 1TAL AREA=393,607 SF(9.04 AC) PROJECT .........allllllll WATERTOWN,MA y I aVIP.AREA=38 7244 SF(8.74 AC) = IUl G a v �- I Drawing Name: , FUTURE- - POST- o I - ----- REDEVELOPMENT - - -- - - - - - a. --�-- WATERSHED PLAN e _ I + I aese�ar.STREET POINT OF ANALYSIS#1-30"PIPE m."`_ED WATERTOWN STORMWATER ana as sT T W ,p 0 3 Q2(3.2 IN)=0.00 CFS=0.000 AF _ 0 Q10(4.9 IN)=0.00 CFS=0.000 AF - - SSI#3 SIZED FOR 100-YR CORNELL STORM a WATERTOWN STORMWATER Drawing No.: o� Q25(6.2 IN)=0.00 CFS=0.000 AF Q100(8.9 IN)=4.28 CFS=0.168 AF 150 0 75 150 300 FIG /7 A EN Project No.: 16041 / GRAPHIC SCALE IN FEET Copyright©2016 by R J.O'Connell&Associates.Inc III. APPENDIX A MassDEP Checklist for Stormwater Report Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report A. Introduction Important:When A Stormwater Report must be submitted with the Notice of Intent permit application to document filling out forms compliance with the Stormwater Management Standards. The following checklist is NOT a substitute for on the computer, (which h h hi Report R t St e Stormwater e wc sou provide more substantive and detailed information use only the tab the p p ) but is offered key to move your here as a tool to help the applicant organize their Stormwater Management documentation for their cursor-do not Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist, use the return the Stormwater Report must contain the engineering computations and supporting information set forth in key. Volume 3 of the Massachusetts Stormwater Handbook. The Stormwater Report must be prepared and certified by a Registered Professional Engineer(RPE) licensed in the Commonwealth. The Stormwater Report must include: • The Stormwater Checklist completed and stamped by a Registered Professional Engineer(see page 2)that certifies that the Stormwater Report contains all required submittals.' This Checklist is to be used as the cover for the completed Stormwater Report. • Applicant/Project Name • Project Address • Name of Firm and Registered Professional Engineer that prepared the Report • Long-Term Pollution Prevention Plan required by Standards 4-6 • Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan required by Standard 82 • Operation and Maintenance Plan required by Standard 9 In addition to all plans and supporting information, the Stormwater Report must include a brief narrative describing stormwater management practices, including environmentally sensitive site design and LID techniques, along with a diagram depicting runoff through the proposed BMP treatment train. Plans are required to show existing and proposed conditions, identify all wetland resource areas, NRCS soil types, critical areas, Land Uses with Higher Potential Pollutant Loads (LUHPPL), and any areas on the site where infiltration rate is greater than 2.4 inches per hour. The Plans shall identify the drainage areas for both existing and proposed conditions at a scale that enables verification of supporting calculations. As noted in the Checklist, the Stormwater Management Report shall document compliance with each of the Stormwater Management Standards as provided in the Massachusetts Stormwater Handbook. The soils evaluation and calculations shall be done using the methodologies set forth in Volume 3 of the Massachusetts Stormwater Handbook. To ensure that the Stormwater Report is complete, applicants are required to fill in the Stormwater Report Checklist by checking the box to indicate that the specified information has been included in the Stormwater Report. If any of the information specified in the checklist has not been submitted, the applicant must provide an explanation. The completed Stormwater Report Checklist and Certification must be submitted with the Stormwater Report. 'The Stormwater Report may also include the Illicit Discharge Compliance Statement required by Standard 10. If not included in the Stormwater Report,the Illicit Discharge Compliance Statement must be submitted prior to the discharge of stormwater runoff to the post-construction best management practices. 2 For some complex projects,it may not be possible to include the Construction Period Erosion and Sedimentation Control Plan in the Stormwater Report. In that event,the issuing authority has the discretion to issue an Order of Conditions that approves the project and includes a condition requiring the proponent to submit the Construction Period Erosion and Sedimentation Control Plan before commencing any land disturbance activity on the site. Stormwater Checklist•04/01/08 Stormwater Report Checklist•Page 1 of 8 LlMassachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report B. Stormwater Checklist and Certification The following checklist is intended to serve as a guide for applicants as to the elements that ordinarily need to be addressed in a complete Stormwater Report. The checklist is also intended to provide conservation commissions and other reviewing authorities with a summary of the components necessary for a comprehensive Stormwater Report that addresses the ten Stormwater Standards. Note: Because stormwater requirements vary from project to project, it is possible that a complete Stormwater Report may not include information on some of the subjects specified in the Checklist. If it is determined that a specific item does not apply to the project under review, please note that the item is not applicable (N.A.) and provide the reasons for that determination. A complete checklist must include the Certification set forth below signed by the Registered Professional Engineer who prepared the Stormwater Report. Registered Professional Engineer's Certification I have reviewed the Stormwater Report, including the soil evaluation, computations, Long-term Pollution Prevention Plan, the Construction Period Erosion and Sedimentation Control Plan (if included), the Long- term Post-Construction Operation and Maintenance Plan, the Illicit Discharge Compliance Statement(if included)and the plans showing the stormwater management system, and have determined that they have been prepared in accordance with the requirements of the Stormwater Management Standards as further elaborated by the Massachusetts Stormwater Handbook. I have also determined that the information presented in the Stormwater Checklist is accurate and that the information presented in the Stormwater Report accurately reflects conditions at the site as of the date of this permit application. Registered Professional Engineer Block and Signature kP�tN OF A4SIP o JOHN J. V STOY m CD 0 CIVIL y � No.42797 � � o APp s-Tr �Q .�4� FS1pNAL �� 4gt nd Date Checklist Project Type: Is the application for new development, redevelopment, or a mix of new and redevelopment? ❑ New development ® Redevelopment ❑ Mix of New Development and Redevelopment Stormwater Checklist•04/01/08 Stormwater Report Checklist•Page 2 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) LID Measures: Stormwater Standards require LID measures to be considered. Document what environmentally sensitive design and LID Techniques were considered during the planning and design of the project: ❑ No disturbance to any Wetland Resource Areas ❑ Site Design Practices (e.g. clustered development, reduced frontage setbacks) ® Reduced Impervious Area (Redevelopment Only) ® Minimizing disturbance to existing trees and shrubs ❑ LID Site Design Credit Requested: ❑ Credit 1 ❑ Credit 2 ❑ Credit 3 ❑ Use of"country drainage" versus curb and gutter conveyance and pipe ❑ Bioretention Cells (includes Rain Gardens) ❑ Constructed Stormwater Wetlands (includes Gravel Wetlands designs) ❑ Treebox Filter ❑ Water Quality Swale ❑ Grass Channel ❑ Green Roof ❑ Other(describe): Standard 1: No New Untreated Discharges ® No new untreated discharges ❑ Outlets have been designed so there is no erosion or scour to wetlands and waters of the Commonwealth ® Supporting calculations specified in Volume 3 of the Massachusetts Stormwater Handbook included. Stormwater Checklist•04/01/08 Stormwater Report Checklist•Page 3 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 2: Peak Rate Attenuation ❑ Standard 2 waiver requested because the project is located in land subject to coastal storm flowage and stormwater discharge is to a wetland subject to coastal flooding. ❑ Evaluation provided to determine whether off-site flooding increases during the 100-year 24-hour storm. ® Calculations provided to show that post-development peak discharge rates do not exceed pre- development rates for the 2-year and 10-year 24-hour storms. If evaluation shows that off-site flooding increases during the 100-year 24-hour storm, calculations are also provided to show that post-development peak discharge rates do not exceed pre-development rates for the 100-year 24- hour storm. Standard 3: Recharge ® Soil Analysis provided. ❑ Required Recharge Volume calculation provided. ❑ Required Recharge volume reduced through use of the LID site Design Credits. ® Sizing the infiltration, BMPs is based on the following method: Check the method used. ❑ Static ® Simple Dynamic ❑ Dynamic Field' ® Runoff from all impervious areas at the site discharging to the infiltration BMP. ❑ Runoff from all impervious areas at the site is not discharging to the infiltration BMP and calculations are provided showing that the drainage area contributing runoff to the infiltration BMPs is sufficient to generate the required recharge volume. ❑ Recharge BMPs have been sized to infiltrate the Required Recharge Volume. ® Recharge BMPs have been sized to infiltrate the Required Recharge Volume only to the maximum extent practicable for the following reason: ❑ Site is comprised solely of C and D soils and/or bedrock at the land surface ❑ M.G.L. c. 21 E sites pursuant to 310 CMR 40.0000 ❑ Solid Waste Landfill pursuant to 310 CMR 19.000 ® Project is otherwise subject to Stormwater Management Standards only to the maximum extent practicable. ® Calculations showing that the infiltration BMPs will drain in 72 hours are provided. ❑ Property includes a M.G.L. c. 21 E site or a solid waste landfill and a mounding analysis is included. 80%TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used. Stormwater Checklist•04/01/08 Stormwater Report Checklist•Page 4 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 3: Recharge (continued) ❑ The infiltration BMP is used to attenuate peak flows during storms greater than or equal to the 10- year 24-hour storm and separation to seasonal high groundwater is less than 4 feet and a mounding analysis is provided. ❑ Documentation is provided showing that infiltration BMPs do not adversely impact nearby wetland resource areas. Standard 4: Water Quality The Long-Term Pollution Prevention Plan typically includes the following: • Good housekeeping practices; • Provisions for storing materials and waste products inside or under cover; • Vehicle washing controls; • Requirements for routine inspections and maintenance of stormwater BMPs; • Spill prevention and response plans; • Provisions for maintenance of lawns, gardens, and other landscaped areas; • Requirements for storage and use of fertilizers, herbicides, and pesticides; • Pet waste management provisions; • Provisions for operation and management of septic systems; • Provisions for solid waste management; • Snow disposal and plowing plans relative to Wetland Resource Areas; • Winter Road Salt and/or Sand Use and Storage restrictions; • Street sweeping schedules; • Provisions for prevention of illicit discharges to the stormwater management system; • Documentation that Stormwater BMPs are designed to provide for shutdown and containment in the event of a spill or discharges to or near critical areas or from LUHPPL; • Training for staff or personnel involved with implementing Long-Term Pollution Prevention Plan; • List of Emergency contacts for implementing Long-Term Pollution Prevention Plan. ® A Long-Term Pollution Prevention Plan is attached to Stormwater Report and is included as an attachment to the Wetlands Notice of Intent. ® Treatment BMPs subject to the 44% TSS removal pretreatment requirement and the one inch rule for calculating the water quality volume are included, and discharge: ❑ is within the Zone II or Interim Wellhead Protection Area ❑ is near or to other critical areas ® is within soils with a rapid infiltration rate (greater than 2.4 inches per hour) ® involves runoff from land uses with higher potential pollutant loads. ❑ The Required Water Quality Volume is reduced through use of the LID site Design Credits. ® Calculations documenting that the treatment train meets the 80% TSS removal requirement and, if applicable, the 44% TSS removal pretreatment requirement, are provided. Stormwater Checklist•04/01/08 Stormwater Report Checklist•Page 5 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 4: Water Quality (continued) ❑ The BMP is sized (and calculations provided) based on: ❑ The '/z" or 1"Water Quality Volume or ❑ The equivalent flow rate associated with the Water Quality Volume and documentation is provided showing that the BMP treats the required water quality volume. ® The applicant proposes to use proprietary BMPs, and documentation supporting use of proprietary BMP and proposed TSS removal rate is provided. This documentation may be in the form of the propriety BMP checklist found in Volume 2, Chapter 4 of the Massachusetts Stormwater Handbook and submitting copies of the TARP Report, STEP Report, and/or other third party studies verifying performance of the proprietary BMPs. ❑ A TMDL exists that indicates a need to reduce pollutants other than TSS and documentation showing that the BMPs selected are consistent with the TMDL is provided. Standard 5: Land Uses With Higher Potential Pollutant Loads (LUHPPLs) ❑ The NPDES Multi-Sector General Permit covers the land use and the Stormwater Pollution Prevention Plan (SWPPP) has been included with the Stormwater Report. ❑ The NPDES Multi-Sector General Permit covers the land use and the SWPPP will be submitted prior to the discharge of stormwater to the post-construction stormwater BMPs. ® The NPDES Multi-Sector General Permit does not cover the land use. ❑ LUHPPLs are located at the site and industry specific source control and pollution prevention measures have been proposed to reduce or eliminate the exposure of LUHPPLs to rain, snow, snow melt and runoff, and been included in the long term Pollution Prevention Plan. ❑ All exposure has been eliminated. ® All exposure has not been eliminated and all BMPs selected are on MassDEP LUHPPL list. ® The LUHPPL has the potential to generate runoff with moderate to higher concentrations of oil and grease (e.g. all parking lots with >1000 vehicle trips per day) and the treatment train includes an oil grit separator, a filtering bioretention area, a sand filter or equivalent. Standard 6: Critical Areas ❑ The discharge is near or to a critical area and the treatment train includes only BMPs that MassDEP has approved for stormwater discharges to or near that particular class of critical area. ❑ Critical areas and BMPs are identified in the Stormwater Report. Stormwater Checklist•04/01/08 Stormwater Report Checklist•Page 6 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 7: Redevelopments and Other Projects Subject to the Standards only to the maximum extent practicable ® The project is subject to the Stormwater Management Standards only to the maximum Extent Practicable as a: ❑ Limited Project ❑ Small Residential Projects: 5-9 single family houses or 5-9 units in a multi-family development provided there is no discharge that may potentially affect a critical area. ❑ Small Residential Projects: 2-4 single family houses or 2-4 units in a multi-family development with a discharge to a critical area ❑ Marina and/or boatyard provided the hull painting, service and maintenance areas are protected from exposure to rain, snow, snow melt and runoff ❑ Bike Path and/or Foot Path ® Redevelopment Project ❑ Redevelopment portion of mix of new and redevelopment. ❑ Certain standards are not fully met (Standard No. 1, 8, 9, and 10 must always be fully met) and an explanation of why these standards are not met is contained in the Stormwater Report. ® The project involves redevelopment and a description of all measures that have been taken to improve existing conditions is provided in the Stormwater Report. The redevelopment checklist found in Volume 2 Chapter 3 of the Massachusetts Stormwater Handbook may be used to document that the proposed stormwater management system (a) complies with Standards 2, 3 and the pretreatment and structural BMP requirements of Standards 4-6 to the maximum extent practicable and (b) improves existing conditions. Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan must include the following information: • Narrative; • Construction Period Operation and Maintenance Plan; • Names of Persons or Entity Responsible for Plan Compliance; • Construction Period Pollution Prevention Measures; • Erosion and Sedimentation Control Plan Drawings; • Detail drawings and specifications for erosion control BMPs, including sizing calculations; • Vegetation Planning; • Site Development Plan; • Construction Sequencing Plan; • Sequencing of Erosion and Sedimentation Controls; • Operation and Maintenance of Erosion and Sedimentation Controls; • Inspection Schedule; • Maintenance Schedule; • Inspection and Maintenance Log Form. ❑ A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan containing the information set forth above has been included in the Stormwater Report. Stormwater Checklist•04/01/08 Stormwater Report Checklist•Page 7 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control (continued) ❑ The project is highly complex and information is included in the Stormwater Report that explains why it is not possible to submit the Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan with the application. A Construction Period Pollution Prevention and Erosion and Sedimentation Control has not been included in the Stormwater Report but will be submitted before land disturbance begins. ❑ The project is not covered by a NPDES Construction General Permit. ❑ The project is covered by a NPDES Construction General Permit and a copy of the SWPPP is in the Stormwater Report. ® The project is covered by a NPDES Construction General Permit but no SWPPP been submitted. The SWPPP will be submitted BEFORE land disturbance begins. Standard 9: Operation and Maintenance Plan ® The Post Construction Operation and Maintenance Plan is included in the Stormwater Report and includes the following information: ® Name of the stormwater management system owners; ® Party responsible for operation and maintenance; ® Schedule for implementation of routine and non-routine maintenance tasks; ❑ Plan showing the location of all stormwater BMPs maintenance access areas; ® Description and delineation of public safety features; ❑ Estimated operation and maintenance budget; and ® Operation and Maintenance Log Form. ❑ The responsible party is not the owner of the parcel where the BM is located and the Stormwater Report includes the following submissions: ❑ A copy of the legal instrument(deed, homeowner's association, utility trust or other legal entity) that establishes the terms of and legal responsibility for the operation and maintenance of the project site stormwater BMPs; ❑ A plan and easement deed that allows site access for the legal entity to operate and maintain BMP functions. Standard 10: Prohibition of Illicit Discharges ® The Long-Term Pollution Prevention Plan includes measures to prevent illicit discharges; ® An Illicit Discharge Compliance Statement is attached; ❑ NO Illicit Discharge Compliance Statement is attached but will be submitted prior to the discharge of any stormwater to post-construction BMPs. Stormwater Checklist•04/01/08 Stormwater Report Checklist•Page 8 of 8 III. APPENDIX B Soils Information prepared by McPhail Associates, LLC Memorandum .P�aww�ftnb% Date: July 6, 2016 Recipient: Boylston Properties Company, Inc. Jeffrey Heidelberg Copy To: RI O'Connell & Associates, Inc. - Roy Smith Sender: Benjamin E. Downing, Jonathan W. Patch, P.E. Project: The Arsenal Project; Watertown, MA Project No: 5573.2.02 Subject: Rawls Infiltration Rate and Seasonal High Groundwater Levels for Stormwater Infiltration System Design This memorandum documents our determination of the Rawls Infiltration Rates and seasonal high groundwater levels for use in the stormwater infiltration system design. Based on the laboratory grain-size distributions of soil samples obtained from the borings and test pits, the soil texture class was determined using the USDA textural triangle. The soil texture class was then used to determine the Rawls Infiltration Rates. It is understood that the Rawls Infiltration Rates are based on research performed by Rawls, Brakensiek and Sexton in 1982 which used laboratory permeability testing to develop a relationship between texture class and saturated permeability. Based on discussions with RI O'Connell & Associates, Inc., the project site civil engineer, there are three (3) proposed areas for stormwater infiltration systems. The attached Table 1 contains information regarding the soil texture class and corresponding Rawls Infiltration Rate for each sample tested, and recommended Rawls Infiltration Rates for each of the proposed systems. Approximate subsurface exploration locations are shown on the attached figure. Groundwater or indications of a seasonal high groundwater level were generally not observed in the test pits performed at the site. However, groundwater was encountered in the borings performed within the vicinity of the proposed infiltration systems and within the groundwater observation wells installed across the site. Based on the groundwater observation well and boring data, the ESHGW level for each of the proposed subsurface stormwater infiltration systems is contained in Table 1. We trust that the above is sufficient for your present requirements. Should you have any questions concerning the recommendations presented herein, please do not hesitate to contact us F:\WP5\JOBS\5573\Letters - Memos\5573_Rawls_Infiltration_Rate_Memo_070616.docx Attachments: Table 1 - USDA Soil Classification Summary Table Figure 2 - Subsurface Exploration Plan GEOTECHNICALAND GEOENVIRONMENTAL ENGINEERS 2269 Massachusetts Avenue Cambridge, Massachusetts 02140 Page 1 of 1 (617) 868-1420 g Table 1 Summary of Recommended Rawls Infiltration Rates and ESHGW The Arsenal Project Job No. 5573 Subsurface Stormwater Subsurface Sample Strata USDA Rawls Recommended Estimated (SS) Infiltration System Exploration Elevation Soil Texture Infiltration Rawls Seasonal Location (ft) Class Rate (in/hr) Infiltration Rate High for System (in/hr) Groundwater (ESHGW) Elevation (ft) SS1-1 18.0 Alluvium Sand 8.27 SS1-1 13.0 Alluvium Sand 8.27 SS1-2 17.0 Alluvium Sand 8.27 SS1 8.27 +8 SS1-2 12.0 Alluvium Sand 8.27 SS1-3 16.5 Alluvium Sand 8.27 SS1-4 11.0 Alluvium Sand 8.27 SS2-1 11.6 Alluvium Loamy Sand 2.41 SS2-1 9.6 Alluvium Sand 8.27 SS2 SS2-2 6.5 Alluvium Sand 8.27 1.02 +4 SS2-3 8.0 Fill Sandy Loam 1.02 SS2-4 8.0 Fill Sandy Loam 1.02 SS3-1 19.7 Fill Loamy Sand 2.41 SS3-2 21.4 Alluvium Sand 8.27 SS3 SS3-2 16.4 Alluvium Sandy Loam 1.02 1.02 +7 SS3-3 24.5 Fill Loamy Sand 2.41 SS3-3 19.5 Fill Loamy Sand 2.41 McPhail Associates, LLC z O S 11T .� _ - .. ►- PROPOSED BUILDING B PROPOSED BUILDING C/D MA=4(OW) ----------- w m 1*5 1.1 55 (OW) �,553-2_ / „� (OW) ��. 53-3 i— -3 \� = w ------ — --- 1 w Nb i I v r GAT \ w \ II / BUILDING E f rI Sir— -L." •1 - "jam q 1 PROPOSED BUILDING F I 1� F+f.3: 0 t / — + I BUILDING A , MA- !;�W) w' r G-2 f � ♦. � -_ 552-3 ♦ M PROPOSED BUILDING G 552-2 R♦ 5524 THE ARSENAL PROJECT m LEGEND WATERTOWN MASSACHUSETTS c� 0— APPROXIMATE LOCATION OF TE5T PIT PERFORMED BY F.E.FRENCH CON5TRUCTION,INC.FROM MAY 9 TO MAY I G,201 G FOR McFHAIL ASSOCIATES,LLC SUBSURFACE EXPLORATION PLAN m N — APPROXIMATE LOCATION OF BORING PERFORMED BY CARR-DEE CORP.FROM MAY 3 TO MAY 13,201 G FOR McFHAIL A550CIATE5,LLC FOR o BOYLSTON PROPERTIES COMPANY, INC. — APPROXIMATE LOCATION OF BORING PERFORMED BY CARR-DEE CORP.FROM MAY 28 TO JUNE 4,2013 FOR McPHAIL A550CIATE5,LLC Geotechnlcal and BY _ (OW) — INDICATES OBSERVATION WELL INSTALLED WITHIN COMPLETED BOREHOLE G202nVifOnnlenta Engineers McFHAIL ASSOCIATES, LLC GRAPHIC 5CA1 E 2269 Massachusetts Avenue Cambridge, MA 02140 z REFERENCE:THIS PLAN WAS PREPARED FROM A 20-SCALE DRAWING ENTITLED,"PARTIAL EXISTING CONDITIONS PLAN"DATED OCTOBER G,2014 PREPARED BY 50 O s0 Io0 200 6171868-1420 FELDMAN LAND 5URVEYOP.5,A 40-5CALE DRAWING ENTITLED,"GROUND FLOOR,SCHEME 15-REFINED,THE APSENAL PROJECT"DATED MARCH 23,201 G PREPARED www.m Date: DUNE 2016 I Dwn: nn a s. I Chkd:J.w P Scale: 1°=so' L BY PCA,AND A 200-5CALE UNDATED DRAWING ENTITLED,"FIGURE 2, 19G8 PROPERTY LAYOUT"BY ABB ENVIRONMENTAL SERVICES,INC. 8-1423(Fax) ww.mcphoilgeo.com Project No: 5573 FIGURE 2 III. APPENDIX C Letter prepared by Linenthal Eisenberg Anderson, Inc. Engineers (LEA) i EuS,m R.Eiunberg is Loma R t A�denon Paul D.Guertin James G..Jac Jacob n Stank.1. in Paul E.Rockerwkft Donald M.Brings Kennelh W.Carlson Michael A.Casmvoy Etlab2iJhed Iq 2922 Ed-ard F.Caaridy.Jr. MichaelFamr Curtis ".Flight Linenthal Eisenberg Anderson, Inc: Engineers unir H. William S Hartley Mule E Kelly r 75 Kneeland Street Boston, Massachusetts 02111 • (617)426-6300 John F.Kin{,Jr. Pcicr B.Knowhon Douglas L.Luton Mch;n J.Locke Gkntt A.LlacWallcr Stanley A.McIntosh Richard K.McMullan David A.Peters Chalks L-Rkci William J.Richmond Paul SalIC vich Alvan E.Shuman Bruce D.Thibodeau Fred N.Tibbo Arthur J.Towne Null D.Weirman September 13, 1985 Arrowstreet, Inc. 14 Arrow Street Cambridge, MA 02138 Attn: Ms. Susan Meyers Re: Hai.vard Community Health Plan Building 51 - Watertown Center Arsenal Mall Watertown, Massachusetts LEA Project No. 85206.02 Dear Madam: As requested, we have reviewed the present sanitary sewerage and storm drainage systems for the subject project to determine that the present systems can accommodate the proposed usage as required by Item 13 and 14 of the City of Watertown as part of their special permit decision 85-85-27. Sanitary Sewer The existing on-site sanitary sewer system consists of a new eight (8) inch P.V.C. line which was installed as part of the Arsenal Marketplace development. The sewer line from the proposed health center (Building 51) will be connected directly to a sewer manhole at the east end of Building 51. From this manhole, the 8-inch sewer runs easterly across the parking area to a manhole in the main entrance drive. This line has a capacity of 1.2 mgd at a velocity of 5.4 fps flowing full. i Linenthal Eisenberg Anderson Inc. September 16, 1985 - 2 - From the main entrance drive, the sewer runs northerly along the entrance drive to a manhole located at the westerly edge of Arsenal Street. The capacity of this 8-inch line is 1.1 mgd at 5.2 fps flowing full. From this manhole, the sewer line runs to an existing manhole located on the northerly side of Arsenal Street. The sewer line across Arsenal Street consists of an B-inch ductile iron pipe with a capacity of 0.9 mgd at 4.0 fps flowing full. The existing manhole is located on the existing 15-inch sanitary sewer in Arsenal Street. Storm Drainage The new on-site storm drainage system was installed as part of the Arsenal Marketplace Mall development. Design of this system was based on a U.S. Weather Bureau Technical Paper No. 40 for a ten (10) year, 30 minute rainfall frequency and an initial fifteen (15) minute time of concentration. Based on this criteria, the total rainfall for design purposes is 4.18 inches. This basis appears to be consistent with the return frequency used for the original Watertown Arsenal and Arsenal Street storm drainage designs. Runoff quantities have been calculated using the rational formula Q - C I A. Pipe sizes have been determined on this basis for full pipe flow using Manning's coefficient n - 0.013 for new concrete pipe. The Arsenal Marketplace -Mall roof and parking areas tributary to the 30" drain in Elm Street, the parking areas tributary to new leaching basins with subsurface disposal of storm water, and parking areas tributary to leaching basins with a 12" perforated overflow pipe connected to the 30" new drain within the Arsenal Marketplace Mall site are tabulated as follows: Tributary Total Volume Percent Surface Area/Acres Area/Acres C.F.S. of Total Roof Areas 0.47 1.06 0.73 2.26 8.95 31.0 Parking Area tributary 5.31 5.31 19.93 69.0 to new 30" NSC (exclud- 7.57 28.88 100.0 ing leaching basin areas) 30" RCP capacity (Elm St.) 35.00 Arsenal Street 6.12 Parking area tributary 0.61 to new leaching basins 0.76 with overflow to 30" NSD 1.37 5.12 Parking area tributary 0.96 to new leaching basins 0.34 without overflow to new 0.06 30" NSD 1.36 5.10 I Linenthal Eisenberg Anderson Inc. September 16, 1985 - 3 - s S The original design calculations included 21.3 acres of the parking area directly tributary to the new 30" drain via a closed system of catch basins and solid piping. During design of the Arsenal Marketplace Mall, a design change reduced this area by 1.37 acres through subsurface recharge via the use of perforated precast concrete leaching basins interconnected with 12" perforated V.C. pipe laid level, and surrounded by a stone filter material. As can be seen from our tabulation, the roof areas represent 31.0 percent (2.26 acres) of the total on-site acre tributary to the 30" NSD in Elm Street (excluding on-site leaching basin areas and Arsenal Street). The Watertown Department of Public Works required that we intercept the existing 12" drain in Arsenal Street at the Elm Street intersection and connect it to the new 30" drain from the Arsenal Marketplace. This was done to relieve flooding problems at the intersection of Arsenal, Arlington and Coolidge Streets. The capacity which has been provided in the 30" R.C.P. to serve Arsenal Street is 6. 12 C.F.S.; in excess of the C.F.S. capacity (approximate) of the existing 12" Arsenal Street drain. New catch basins have been constructed along the south side of Arsenal Street (under the Town of Watertown/Massachusetts DPW Arsenal Street Reconstruction Project) in the vicinity of the new 30" storm drain and have been connected to the new drain. The areas of building roof, pavement, landscaping, and runoff characteristics are essentially the same for the proposed health facility as the basis used for the original design of the new storm drainage system. The new storm drainage system drains the westerly portion of the Arsenal Mall site adjacent to Arsenal Street and discharges through a separate 30-inch outfall drain down Elm Street to the existing Elm Street culvert. On the basis of the original design for the Arsenal Mall sanitary sewerage and storm drainage systems and the proposed use of Building 51 and its new addition for the Harvard Community Health Plan, there is adequate capacity for the existing and proposed uses on the site. Please call•me directly with any questions. Very truly yours, LINENTHAL EISENBERG ANDERSON, INC. C.Gi•�.• Arthur J. Towne Project Manager AJT/dd/DlO IV. APPENDIX D Computations Pre-Redevelopment Hydrological Computations :POA-3B POA-3A POA-2 18'�ipe 20 ipe 15'�ipe HDEX-3B EX-3A EX-2 Home Depot Parking East Portion of Lot South Portion of Lot EX-1 A EX-1 B North ortion of Lot HVMA Lot POA-1 30" Pipe SubCat Reach on Link Routing Diagram for The Arsenal Project-Existing Prepared by RJO'Connell&Associates, Inc., Printed 6/14/2016 HydroCAD®10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC The Arsenal Project-Existing Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 2 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentEX-1A: North Portion of LotRunoff Area=320,092 sf 90.90% Impervious Runoff Depth>2.44" Tc=6.0 min CN=93 Runoff=19.94 cfs 1.497 of Subcatchment EX-1 B: HVMA Lot Runoff Area=105,011 sf 77.37% Impervious Runoff Depth>2.17" Tc=6.0 min CN=90 Runoff=5.93 cfs 0.435 of SubcatchmentEX-2: South Portion of Lot Runoff Area=199,264 sf 93.48% Impervious Runoff Depth>2.75" Tc=6.0 min CN=96 Runoff=13.41 cfs 1.047 of SubcatchmentEX-3A: East Portion of Lot Runoff Area=101,042 sf 87.26% Impervious Runoff Depth>2.44" Tc=6.0 min CN=93 Runoff=6.30 cfs 0.472 of SubcatchmentHDEX-3B: Home Depot Runoff Area=74,949 sf 93.08% Impervious Runoff Depth>2.64" Tc=6.0 min CN=95 Runoff=4.93 cfs 0.379 of Link POA-1: 30" Pipe Inflow=25.88 cfs 1.932 of Primary=25.88 cfs 1.932 of Link POA-2: 15" Pipe Inflow=13.41 cfs 1.047 of Primary=13.41 cfs 1.047 of Link POA-3A:24" Pipe Inflow=6.30 cfs 0.472 of Primary=6.30 cfs 0.472 of Link POA-313: 18" Pipe Inflow=4.93 cfs 0.379 of Primary=4.93 cfs 0.379 of Total Runoff Area = 18.374 ac Runoff Volume = 3.831 of Average Runoff Depth = 2.50" 10.48% Pervious = 1.926 ac 89.52% Impervious = 16.447 ac The Arsenal Project-Existing Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 3 Summary for Subcatchment EX-1A: North Portion of Lot Runoff = 19.94 cfs @ 12.09 hrs, Volume= 1.497 af, Depth> 2.44" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 29,113 39 >75% Grass cover, Good, HSG A 49,302 98 Roofs, HSG A 241,677 98 Paved parkinq, HSG A 320,092 93 Weighted Average 29,113 9.10% Pervious Area 290,979 90.90% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-1A: North Portion of Lot Hydrograph 22=!/�— � � — _ �_ — ❑Runoff 21 I — — 11 19.94 cfs - 20 19� Y I 241r� — 18�-'!-2�Yoar4COrnbll Railnfoll�3.4" I � 1 1 4 1 A - 17L 16 unoff-Area=3_20 Q92 sf - 15- ur off-V�N ne-1.4914 � - - 12 .O miIrir — TN-=93L� 81_ + -I = 5�— a _ ::I T- 1 - 1 r . .. .. .. :..�:..�... ... ...,....,�..., 0 1 2 3 4 5 6 7 8 9 10:.11 12 13 14 15 16 17,: 18,. 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 4 Summary for Subcatchment EX-1 B: HVMA Lot Runoff = 5.93 cfs @ 12.09 hrs, Volume= 0.435 af, Depth> 2.17" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 23,761 61 >75% Grass cover, Good, HSG B 18,625 98 Roofs, HSG B 62,625 98 Paved parkinq, HSG B 105,011 90 Weighted Average 23,761 22.63% Pervious Area 81,250 77.37% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-1 B: HVMA Lot Hydrograph -/I ❑Runoff 5.93 cfs 6�I Type III 24-he I_2�YOar Corn 0Il_Ral&OIL=�3.20"i 5�I un� ff Area=1 g5,Q11II sfLL runoff Volume_0.435 of 4�-/I Runoff'D6ptlh>2.17" 3 CFN=q90 min LL 1 0 /:.../:... .. .. .. ..�...�.../:.../.... .... :..., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 5 Summary for Subcatchment EX-2: South Portion of Lot Runoff = 13.41 cfs @ 12.09 hrs, Volume= 1.047 af, Depth> 2.75" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 12,988 61 >75% Grass cover, Good, HSG B 172,371 98 Roofs, HSG B 13,905 98 Paved parkinq, HSG B 199,264 96 Weighted Average 12,988 6.52% Pervious Area 186,276 93.48% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-2: South Portion of Lot Hydrograph 15—/I _ p Runoff 1a� 13.41 cfs t-- I 4- 13�'/' T�_p� 1U�24-T1� 12�'/12�Yoar ICornoll Ftailnfoll�3.?O" 11 unoff ArIea=I 9, 6�sf10-> unoff�Vdlu�ne 1 4of - 9�I Rlunoff D4Rtlh>2.7$" 7� CFN=96 _ LL 6L t L L L L L LL L L LL 5'_/ 4� L LI IL LL fiI IL LL 3� L L 1 L LL L LL 2-:�/ , ' 1 L T- 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 6 Summary for Subcatchment EX-3A: East Portion of Lot Runoff = 6.30 cfs @ 12.09 hrs, Volume= 0.472 af, Depth> 2.44" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 12,868 61 >75% Grass cover, Good, HSG B 9,302 98 Roofs, HSG B 78,872 98 Paved parkinq, HSG B 101,042 93 Weighted Average 12,868 12.74% Pervious Area 88,174 87.26% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-3A: East Portion of Lot Hydrograph 7-/ 17 F -T _ ❑Runoff 6� _Typ� 1 Fr2411� — 6.30 cfs 2�Yoar Cornell F2alnfoll�3.�0"I �=ff-Area�11�,q4� sf- ff Volue-0.47 a = -Ruirrbff Depth>I " -t w 4 3 - '-9 - 3'in 1� ...,.. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 7 Summary for Subcatchment HDEX-3B: Home Depot Parking Runoff = 4.93 cfs @ 12.09 hrs, Volume= 0.379 af, Depth> 2.64" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 5,183 61 >75% Grass cover, Good, HSG B 69,766 98 Paved parkinq, HSG B 74,949 95 Weighted Average 5,183 6.92% Pervious Area 69,766 93.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment HDEX-3B: Home Depot Parking Hydrograph - ❑Runoff Ty1 11 4.93 cfs pe III 24-hlr 2�Yoar ICornoll F2alnfoll�3.gO` 4�I unpff-Area=79 unoff Volume-0.37 a -Runoff Depth>2.64" w 3 T =q.0 min 3 CFN-95 0 L 2. - I � 1 i 0 �..�..�... ...., 0 1 2 3 4 5 Ei 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 8 Summary for Link POA-1: 30" Pipe Inflow Area = 9.759 ac, 87.56% Impervious, Inflow Depth > 2.38" for 2-Year Cornell event Inflow = 25.88 cfs @ 12.09 hrs, Volume= 1.932 of Primary = 25.88 cfs @ 12.09 hrs, Volume= 1.932 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-1: 30" Pipe Hydrograph / ❑Inflow 28" ❑Primary .88 26 Inflow Area=9.7. ,.. , cfs 24- 22 20 18 w 16 u 3 14 o - —}LL 12- 10 8 — 6 4 2 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 9 Summary for Link POA-2: 15" Pipe Inflow Area = 4.574 ac, 93.48% Impervious, Inflow Depth > 2.75" for 2-Year Cornell event Inflow = 13.41 cfs @ 12.09 hrs, Volume= 1.047 of Primary = 13.41 cfs @ 12.09 hrs, Volume= 1.047 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-2: 15" Pipe Hydrograph 15=/' I❑Inflow p Primary 14?� Inflow Area=4.5 13.41 cfs 13- I � 12� � 10- 9�z -4 I— $� � I IT TIT TI 1 T 0 7 4� 3� 2� �- 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 10 Summary for Link POA-3A: 24" Pipe Inflow Area = 2.320 ac, 87.26% Impervious, Inflow Depth > 2.44" for 2-Year Cornell event Inflow = 6.30 cfs @ 12.09 hrs, Volume= 0.472 of Primary = 6.30 cfs @ 12.09 hrs, Volume= 0.472 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-3A: 24" Pipe Hydrograph 7-/ ❑Inflow 6.30 cfs ❑Primary Inflow Area=2.3 6 5 ci 4 3 0 LL 3 2 1 0 �..r..�.. ........... /....,.. . 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 11 Summary for Link POA-313: 18" Pipe Inflow Area = 1.721 ac, 93.08% Impervious, Inflow Depth > 2.64" for 2-Year Cornell event Inflow = 4.93 cfs @ 12.09 hrs, Volume= 0.379 of Primary = 4.93 cfs @ 12.09 hrs, Volume= 0.379 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-313: 18" Pipe Hydrograph / ❑Inflow ❑Primary 5 Inflow Area=1 .7 4.93 cfs 4- 3 u 3 0 LL 2 1 0 ...... ..... .... ......... ......... ........... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 12 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentEX-1A: North Portion of LotRunoff Area=320,092 sf 90.90% Impervious Runoff Depth>4.10" Tc=6.0 min CN=93 Runoff=32.48 cfs 2.509 of Subcatchment EX-1 B: HVMA Lot Runoff Area=105,011 sf 77.37% Impervious Runoff Depth>3.78" Tc=6.0 min CN=90 Runoff=10.09 cfs 0.759 of SubcatchmentEX-2: South Portion of Lot Runoff Area=199,264 sf 93.48% Impervious Runoff Depth>4.43" Tc=6.0 min CN=96 Runoff=21.05 cfs 1.689 of SubcatchmentEX-3A: East Portion of Lot Runoff Area=101,042 sf 87.26% Impervious Runoff Depth>4.10" Tc=6.0 min CN=93 Runoff=10.25 cfs 0.792 of SubcatchmentHDEX-3B: Home Depot Runoff Area=74,949 sf 93.08% Impervious Runoff Depth>4.32" Tc=6.0 min CN=95 Runoff=7.83 cfs 0.619 of Link POA-1: 30" Pipe Inflow=42.57 cfs 3.268 of Primary=42.57 cfs 3.268 of Link POA-2: 15" Pipe Inflow=21.05 cfs 1.689 of Primary=21.05 cfs 1.689 of Link POA-3A:24" Pipe Inflow=10.25 cfs 0.792 of Primary=10.25 cfs 0.792 of Link POA-313: 18" Pipe Inflow=7.83 cfs 0.619 of Primary=7.83 cfs 0.619 of Total Runoff Area = 18.374 ac Runoff Volume = 6.368 of Average Runoff Depth = 4.16" 10.48% Pervious = 1.926 ac 89.52% Impervious = 16.447 ac The Arsenal Project-Existing Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 13 Summary for Subcatchment EX-1A: North Portion of Lot Runoff = 32.48 cfs @ 12.09 hrs, Volume= 2.509 af, Depth> 4.10" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 29,113 39 >75% Grass cover, Good, HSG A 49,302 98 Roofs, HSG A 241,677 98 Paved parkinq, HSG A 320,092 93 Weighted Average 29,113 9.10% Pervious Area 290,979 90.90% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-1A: North Portion of Lot Hydrograph — 36-' ■Runoff 34 32.48 cfs T 32_ _Type l U 211--h r 30_ —11p-YearClornell Rainfall-"01' I 1 - 1 __1 - 2a✓ uno FUArIea=320 921 sf - - - 24= unoff Vdlu�ne-2.509 a 22 -' -IuMlo"6pth>*1 " —I - 20= -T - .0-min- 318T 16 I—I T TI _J T IT T —I T T1 - - � _ =9 LL _ 147' _ I T _T 1 7 T I T _T T T T T T 7 12� _ 1oT T 1 T T ' — TT T T $� T T r- T 1 T - 6T 2 / T o- :... '... ..4.�..,�..�..�...�:...�:...�....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 14 Summary for Subcatchment EX-1 B: HVMA Lot Runoff = 10.09 cfs @ 12.09 hrs, Volume= 0.759 af, Depth> 3.78" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 23,761 61 >75% Grass cover, Good, HSG B 18,625 98 Roofs, HSG B 62,625 98 Paved parkinq, HSG B 105,011 90 Weighted Average 23,761 22.63% Pervious Area 81,250 77.37% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-1 B: HVMA Lot Hydrograph _ _ 11-:z ❑Runoff 10� T� 10.0 cfs 11�24-h� 9 9�,/I 1p-Yeal- Clorrhell Roinfall�4 I' $� unoff-Arlea=105,Qt11 s L unoff Vdlume=0.7%9�# 7�I Rlunoff DOpth>3.78" .2 5� =90 0 2� —1 T 1 T F -1 T F -1 1 o ,:... ../... .. .. :..�'..r:...,:...,....,....,�..., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 15 Summary for Subcatchment EX-2: South Portion of Lot Runoff = 21.05 cfs @ 12.09 hrs, Volume= 1.689 af, Depth> 4.43" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 12,988 61 >75% Grass cover, Good, HSG B 172,371 98 Roofs, HSG B 13,905 98 Paved parkinq, HSG B 199,264 96 Weighted Average 12,988 6.52% Pervious Area 186,276 93.48% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-2: South Portion of Lot Hydrograph 23- — ■Runoff 21 I 11 C �21.05 cfs _I L I B 20/— —pe 1�24- — — — — — - 19- 1p�{ea-Clorrhell R$uifaU1 4�90T- — —I - 18 unoff�►rIea=199 s — -_ 16 Iur�rofffi dh�rine�l a fi fi 15: 14 �lu6off Opth>*4 " -4 4- - 1-1 4 t- I —I - 12 .Orrin 11 _9"_ 6Y-- — — — — — LL 10: —s= - 7-'' I � I f I r � I � + 6 I � I -1 - — 3- — 2= 1=' 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 16 Summary for Subcatchment EX-3A: East Portion of Lot Runoff = 10.25 cfs @ 12.09 hrs, Volume= 0.792 af, Depth> 4.10" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 12,868 61 >75% Grass cover, Good, HSG B 9,302 98 Roofs, HSG B 78,872 98 Paved parkinq, HSG B 101,042 93 Weighted Average 12,868 12.74% Pervious Area 88,174 87.26% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-3A: East Portion of Lot Hydrograph 11� O Runoff 10.25 cfs 10� T�-p 11-�2" 4 — 9� —I p-fea�-CorOeTR#infaI I=4.901' - —I T I - 1 lIII ,QQA�2 sf 8� �u-noff-Area= 01 unoff Vdlu�ne=0. 9� of 7� RlunW D406>00" 3 6� T = .O�I`miln I I L I -1 _L I I I —L L I - CI V LL 4� 2� _T F 1� 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 17 Summary for Subcatchment HDEX-3B: Home Depot Parking Runoff = 7.83 cfs @ 12.09 hrs, Volume= 0.619 af, Depth> 4.32" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 5,183 61 >75% Grass cover, Good, HSG B 69,766 98 Paved parkinq, HSG B 74,949 95 Weighted Average 5,183 6.92% Pervious Area 69,766 93.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment HDEX-3B: Home Depot Parking Hydrograph 7.83 cfs Runoff $�l Type 111124�hr1 7���QYeai��rn�lf�ta�nf�l�{4.9Q" Runoff Ar a=74 94 sf 6�i Rune ff 1fi/oI urr ( 19 laft - -2un'ffPe '"2J' —t 5_ Tc=6.0 min ��N=�0 4 5 L 3� 2 1- 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 18 Summary for Link POA-1: 30" Pipe Inflow Area = 9.759 ac, 87.56% Impervious, Inflow Depth > 4.02" for 10-Year Cornell event Inflow = 42.57 cfs @ 12.09 hrs, Volume= 3.268 of Primary = 42.57 cfs @ 12.09 hrs, Volume= 3.268 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-1: 30" Pipe Hydrograph — I _L ❑Inflow 46 0 Primary 44 ,—Inflow42 Area-9.7 42.57 cfs =1 1= 40 14 �- 1 ­4 �- 1 -1 �- I- 38 — 36 3a ,- 1 1 L IB _L I I I L1 1L I I I 32 30 — 14 � 1 � 4- 1 1 � - 14 � I � +- 1 -1 + 28 24 0 22 — LL18 - - - - - - - I- I I - - - - I - I 16 � I � � I � � 1 1 14 I 12 10I t tl - fi1 -1 t1 8: — — 6 4"j — — 2 0 ..../....(: �... .. .. ...:...(:.../:... .../.... :...,,..., ...,....,.. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 19 Summary for Link POA-2: 15" Pipe Inflow Area = 4.574 ac, 93.48% Impervious, Inflow Depth > 4.43" for 10-Year Cornell event Inflow = 21.05 cfs @ 12.09 hrs, Volume= 1.689 of Primary = 21.05 cfs @ 12.09 hrs, Volume= 1.689 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-2: 15" Pipe Hydrograph L - - - - ❑Inflow 22 21.05 cfs — I 0 Primary 21 �_I'AO�-v A�-e -4.5 18II � I 17i �— 14� -— — 13%� — c 11%/ � - - - - I - I fil I - 1 - - - 8fit I fi l 6, 5: 4%� 2 1� 0 ..................... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 20 Summary for Link POA-3A: 24" Pipe Inflow Area = 2.320 ac, 87.26% Impervious, Inflow Depth > 4.10" for 10-Year Cornell event Inflow = 10.25 cfs @ 12.09 hrs, Volume= 0.792 of Primary = 10.25 cfs @ 12.09 hrs, Volume= 0.792 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-3A: 24" Pipe Hydrograph ❑Inflow 11-� ❑Primary 10 Inflow Area=2.3110,25 cfs a� 7� — I _L L1 -1 LI _I N 3 FL 5-' 3 2� 1� 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 21 Summary for Link POA-313: 18" Pipe Inflow Area = 1.721 ac, 93.08% Impervious, Inflow Depth > 4.32" for 10-Year Cornell event Inflow = 7.83 cfs @ 12.09 hrs, Volume= 0.619 of Primary = 7.83 cfs @ 12.09 hrs, Volume= 0.619 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-313: 18" Pipe Hydrograph /I 1 I°Inflow $� I Inflow Area=1 .7 7.83 cfs °Primary 6 N 6- I T TIT T I F T T = T T TIT TIT I I T TIT TIT T 0 4� 2� +- I 4 I I I - 1 4 1� 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 22 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentEX-1A: North Portion of LotRunoff Area=320,092 sf 90.90% Impervious Runoff Depth>5.38" Tc=6.0 min CN=93 Runoff=41.96 cfs 3.292 of Subcatchment EX-1 B: HVMA Lot Runoff Area=105,011 sf 77.37% Impervious Runoff Depth>5.04" Tc=6.0 min CN=90 Runoff=13.24 cfs 1.012 of SubcatchmentEX-2: South Portion of Lot Runoff Area=199,264 sf 93.48% Impervious Runoff Depth>5.72" Tc=6.0 min CN=96 Runoff=26.85 cfs 2.182 of SubcatchmentEX-3A: East Portion of Lot Runoff Area=101,042 sf 87.26% Impervious Runoff Depth>5.38" Tc=6.0 min CN=93 Runoff=13.24 cfs 1.039 of SubcatchmentHDEX-3B: Home Depot Runoff Area=74,949 sf 93.08% Impervious Runoff Depth>5.61" Tc=6.0 min CN=95 Runoff=10.02 cfs 0.804 of Link POA-1: 30" Pipe Inflow=55.20 cfs 4.304 of Primary=55.20 cfs 4.304 of Link POA-2: 15" Pipe Inflow=26.85 cfs 2.182 of Primary=26.85 cfs 2.182 of Link POA-3A:24" Pipe Inflow=13.24 cfs 1.039 of Primary=13.24 cfs 1.039 of Link POA-313: 18" Pipe Inflow=10.02 cfs 0.804 of Primary=10.02 cfs 0.804 of Total Runoff Area = 18.374 ac Runoff Volume = 8.329 of Average Runoff Depth = 5.44" 10.48% Pervious = 1.926 ac 89.52% Impervious = 16.447 ac The Arsenal Project-Existing Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 23 Summary for Subcatchment EX-1A: North Portion of Lot Runoff = 41.96 cfs @ 12.09 hrs, Volume= 3.292 af, Depth> 5.38" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 29,113 39 >75% Grass cover, Good, HSG A 49,302 98 Roofs, HSG A 241,677 98 Paved parkinq, HSG A 320,092 93 Weighted Average 29,113 9.10% Pervious Area 290,979 90.90% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-1A: North Portion of Lot Hydrograph 46/ I — — — ■Runoff 44_ ``,, 1 41.96 cfs - 42��7 iF�241r� I F — 38 1, 25-yea�-CIorihell�R fai�--"Ol' —I I � - 36- — 34� unoff Area-3 , 2 sf 32 �_ uY�ioff�tic�la�,_-3. 1 a = t 1 1 = 30��unlo"Optlh>�3 " --44 1 4 1 — - 28- 26� — .0 min —_ 3 24_ f fi fi — o 22- -9 LL 20],/— 16 — — 6- — 4- 4 - 4 2 0- /:.../: .. ..�..�..�..�...�:.../:.../...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 24 Summary for Subcatchment EX-1 B: HVMA Lot Runoff = 13.24 cfs @ 12.09 hrs, Volume= 1.012 af, Depth> 5.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 23,761 61 >75% Grass cover, Good, HSG B 18,625 98 Roofs, HSG B 62,625 98 Paved parkinq, HSG B 105,011 90 Weighted Average 23,761 22.63% Pervious Area 81,250 77.37% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-1 B: HVMA Lot Hydrograph .�� I I ❑Runoff 14->/ 11 13� T�� 11�24-h� 13.24 cfs � � � 12�-/1 25-yeat Coroel� Roinfallp6�201' I I I I _ 11�_Runoff ArlIea=I1 5,��11 sff� 10�l �unoff�Vdlu�ne1.01 of fi — — 9—/I kun nth>_$ 0 " _J L — 8� .o�r"I'LI rt f— fi l LL 5� —1T 3' o :... '... .. .. ..�..�..�:..�:...�:...,....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 25 Summary for Subcatchment EX-2: South Portion of Lot Runoff = 26.85 cfs @ 12.09 hrs, Volume= 2.182 af, Depth> 5.72" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 12,988 61 >75% Grass cover, Good, HSG B 172,371 98 Roofs, HSG B 13,905 98 Paved parkinq, HSG B 199,264 96 Weighted Average 12,988 6.52% Pervious Area 186,276 93.48% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-2: South Portion of Lot Hydrograph — O Runoff 28� 26.85 cfs 26�' T�/� 1�4-T1� t— — 24�-/I 25-yeat Coroel� Roinfallp6�201' 1 _ 11 1 _ 22 �uoffArlIea19, sf� + 20� unoff VdlU -1 8 a 18�'/1 Rlunoff DOpth>$12" 16�'/ TF .O�min fi rtI + H -f I - 0 CN=96 _ LL12� 1 � L 1 _L L � I L1 -1 1 U -L LIB 10� _ $✓ I � fil Irt � I � fil � I Irt � I � 6� I � L 1 LI -1 L L � 4-`/ 2✓ r o :... :... '... ... .. ..�..�..�...r:...�:...�....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 26 Summary for Subcatchment EX-3A: East Portion of Lot Runoff = 13.24 cfs @ 12.09 hrs, Volume= 1.039 af, Depth> 5.38" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 12,868 61 >75% Grass cover, Good, HSG B 9,302 98 Roofs, HSG B 78,872 98 Paved parkinq, HSG B 101,042 93 Weighted Average 12,868 12.74% Pervious Area 88,174 87.26% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-3A: East Portion of Lot Hydrograph .�� I ❑Runoff 14->/ 11 13� T�� 11�24-h� 13.24 cfs � � � 12�-/1 25-yeat Coroel� Roinfallp6�201' 11� Runoff ArlIea-I1 1, 4211 sff� 10�I %noff�Vdlu ( �39 of fi — 9—/I kunoff�D nth>.3 ! I_ 8� '0117'�I�I rt l fi l _NL=93__ — — — — — LL 6� I _J L 1 1 LI -1 L t L - 5 4� I -1 fi I I rt r-- I I t- I -1 T fi � I -I 3' z� 0 :... ... .. .. .. .. ..� ..r ...�:...,....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 27 Summary for Subcatchment HDEX-3B: Home Depot Parking Runoff = 10.02 cfs @ 12.09 hrs, Volume= 0.804 af, Depth> 5.61" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 5,183 61 >75% Grass cover, Good, HSG B 69,766 98 Paved parking, HSG B 74,949 95 Weighted Average 5,183 6.92% Pervious Area 69,766 93.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment HDEX-3B: Home Depot Parking Hydrograph 11� � � � i ❑Runoff 11 10.02 cfs 10� T� 11�24-h� 7 saI 25-yea� Cornell R$infallp6�20" $� u>noff-4rlea=749 f1 unoo Vd1ume'0 a# 6' T �.?71,n 1 5� 4=95 LL 4� 3-,/ fi t r —J -r 0 ...�..�..�..�. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 28 Summary for Link POA-1: 30" Pipe Inflow Area = 9.759 ac, 87.56% Impervious, Inflow Depth > 5.29" for 25-Year Cornell event Inflow = 55.20 cfs @ 12.09 hrs, Volume= 4.304 of Primary = 55.20 cfs @ 12.09 hrs, Volume= 4.304 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-1: 30" Pipe Hydrograph / ❑Inflow 60 — ❑Primary fl 55 —Inflow Are_a=9.7 55.20 cfs � T 50 45 40 ,i 35 u 3 30 0 LL 25 20 15 10 5 0 ...... ..............4.(//..r..�/.......,..../....(....,....,....,I............ . 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 29 Summary for Link POA-2: 15" Pipe Inflow Area = 4.574 ac, 93.48% Impervious, Inflow Depth > 5.72" for 25-Year Cornell event Inflow = 26.85 cfs @ 12.09 hrs, Volume= 2.182 of Primary = 26.85 cfs @ 12.09 hrs, Volume= 2.182 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-2: 15" Pipe Hydrograph 30=� ❑Inflow ' I I � a5 CfS ❑Primary 28�� n-lO�V- A� &-e 4. 26. 5 26 24- t + 20� � 16' IT TITTI ITI 0LL 14? l l 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 30 Summary for Link POA-3A: 24" Pipe Inflow Area = 2.320 ac, 87.26% Impervious, Inflow Depth > 5.38" for 25-Year Cornell event Inflow = 13.24 cfs @ 12.09 hrs, Volume= 1.039 of Primary = 13.24 cfs @ 12.09 hrs, Volume= 1.039 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-3A: 24" Pipe Hydrograph ❑Inflow ❑Primary Inflow Area=2.3 14 13.24 cfs 13� 12� � 113-'/ 10� N u 8- o T/ LL 6� ate' 3=� 2� 1� 0 �..�..r../. ....., .../.... ....,'...................... . 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 31 Summary for Link POA-313: 18" Pipe Inflow Area = 1.721 ac, 93.08% Impervious, Inflow Depth > 5.61" for 25-Year Cornell event Inflow = 10.02 cfs @ 12.09 hrs, Volume= 0.804 of Primary = 10.02 cfs @ 12.09 hrs, Volume= 0.804 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-313: 18" Pipe Hydrograph ❑Inflow 11� ❑Primary 10 Inflow Area=1 .7 10.- cfs N " 5� I _T T_ I -1 2-1/ 1� 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 32 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentEX-1A: North Portion of LotRunoff Area=320,092 sf 90.90% Impervious Runoff Depth>8.05" Tc=6.0 min CN=93 Runoff=61.44 cfs 4.930 of Subcatchment EX-1 B: HVMA Lot Runoff Area=105,011 sf 77.37% Impervious Runoff Depth>7.69" Tc=6.0 min CN=90 Runoff=19.72 cfs 1.544 of SubcatchmentEX-2: South Portion of Lot Runoff Area=199,264 sf 93.48% Impervious Runoff Depth>8.41" Tc=6.0 min CN=96 Runoff=38.82 cfs 3.207 of SubcatchmentEX-3A: East Portion of Lot Runoff Area=101,042 sf 87.26% Impervious Runoff Depth>8.05" Tc=6.0 min CN=93 Runoff=19.39 cfs 1.556 of SubcatchmentHDEX-3B: Home Depot Runoff Area=74,949 sf 93.08% Impervious Runoff Depth>8.29" Tc=6.0 min CN=95 Runoff=14.54 cfs 1.189 of Link POA-1: 30" Pipe Inflow=81.16 cfs 6.475 of Primary=81.16 cfs 6.475 of Link POA-2: 15" Pipe Inflow=38.82 cfs 3.207 of Primary=38.82 cfs 3.207 of Link POA-3A:24" Pipe Inflow=19.39 cfs 1.556 of Primary=19.39 cfs 1.556 of Link POA-313: 18" Pipe Inflow=14.54 cfs 1.189 of Primary=14.54 cfs 1.189 of Total Runoff Area = 18.374 ac Runoff Volume = 12.427 of Average Runoff Depth = 8.12" 10.48% Pervious = 1.926 ac 89.52% Impervious = 16.447 ac The Arsenal Project-Existing Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 33 Summary for Subcatchment EX-1A: North Portion of Lot Runoff = 61.44 cfs @ 12.09 hrs, Volume= 4.930 af, Depth> 8.05" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 29,113 39 >75% Grass cover, Good, HSG A 49,302 98 Roofs, HSG A 241,677 98 Paved parkinq, HSG A 320,092 93 Weighted Average 29,113 9.10% Pervious Area 290,979 90.90% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-1A: North Portion of Lot Hydrograph /I I 1 ❑Runoff 65-:�/ 61.44 cfs II2 4hr 14 55-�/1 1 90-yeor porhell Roin fall�&PO'J 50� -Runoff-Ar a-320,092- f - - 45�kR�> ff�1tO1ume=4.91 Zf — - 40�/rR�"ff-Pepth>8.05'�- -I T _T t- I -Tc=6.0-min - - - 3 35- -C"3L I L L I __1 L 1-1 _L LL 30-:�/ 20 15� 101Z 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 34 Summary for Subcatchment EX-1 B: HVMA Lot Runoff = 19.72 cfs @ 12.09 hrs, Volume= 1.544 af, Depth> 7.69" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 23,761 61 >75% Grass cover, Good, HSG B 18,625 98 Roofs, HSG B 62,625 98 Paved parkinq, HSG B 105,011 90 Weighted Average 23,761 22.63% Pervious Area 81,250 77.37% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-1 B: HVMA Lot Hydrograph 22/ 1 -7 L — _ - ■Runoff 21- — __II -- — — 19.72 cfs 20 18_/�190-Yeargoroe4�R f 8_-�O'1- - + 1 1 - - 17- -Runoff-Ar a=1 ,011- 15�� -_ 1 Jzluzff o17ua�e�.54�4�f f 13 �Rluffe� P9'� L I __1 1 11 1 L I __1 - 12� -Tc-6.0-min — - 311� C"- 0� 1 4 � 1 -4 4 4 1 � 4- 1 1 4 1 -I - -°° 10 — - 8- - I - - I - - - fi I � fi =1 � 1 -I = �— _ _ 6 i_ I171 17C I -IT T_ -I - �— _ 3� - 2�' 4 4 1 0- �:...�... .... .... .........�...�...�...�:...�.... ...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 35 Summary for Subcatchment EX-2: South Portion of Lot Runoff = 38.82 cfs @ 12.09 hrs, Volume= 3.207 af, Depth> 8.41" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 12,988 61 >75% Grass cover, Good, HSG B 172,371 98 Roofs, HSG B 13,905 98 Paved parkinq, HSG B 199,264 96 Weighted Average 12,988 6.52% Pervious Area 186,276 93.48% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-2: South Portion of Lot Hydrograph 42- — — O Runoff 40- �— 38� p� T� 11 4 hr 38.82 cfs - 33�rl Q0-(ear Cornell Rainfall=8.90'1 _T r -I T _T t- I - 32 Runoff Ar a=19 2 4 f 28_ - 26-/ R� "ff_pepthP8441'� ! —I - 24_�� -Tc=6.0-m in - 22- 4- 1 1 _+ �_ I - t I + 1 1 _+ t- I — - 16� — 14 12 —1 T T_ I - 8 6- z'' o :... .... ... .... .... ....�..�...r:...�:...�....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 36 Summary for Subcatchment EX-3A: East Portion of Lot Runoff = 19.39 cfs @ 12.09 hrs, Volume= 1.556 af, Depth> 8.05" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 12,868 61 >75% Grass cover, Good, HSG B 9,302 98 Roofs, HSG B 78,872 98 Paved parkinq, HSG B 101,042 93 Weighted Average 12,868 12.74% Pervious Area 88,174 87.26% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment EX-3A: East Portion of Lot Hydrograph �i -4 - - 21/ O Runoff - i— _ 19.39 cfs 20 19� IIL24-hr 18 j 1 90-(ear Cornell Rainfall=8.90'1 111467�-/_ Runoff Ar11 a=101 042 f 15-/.—R ur �e�.516l � - E � 1 I � I � - - - 13-/1Rlugff_pephP8405'� -4 1 - 1 4 1 — - 12 -Tc=6.0-min - 010 C"3 t 6: - 4 3- I � o` :... :... '... ... .. ..�..�..�...r:...�:...�....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 37 Summary for Subcatchment HDEX-3B: Home Depot Parking Runoff = 14.54 cfs @ 12.09 hrs, Volume= 1.189 af, Depth> 8.29" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 5,183 61 >75% Grass cover, Good, HSG B 69,766 98 Paved parkinq, HSG B 74,949 95 Weighted Average 5,183 6.92% Pervious Area 69,766 93.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment HDEX-3B: Home Depot Parking Hydrograph 16Z � t- � � � � - ■Runoff 15�� I- 14.54 cfs 14���/ 111 24 i --t 13�-/ QO ye*r q roe]�R�in 7 1 1 -1 _ Runoff Ar a-74,949 sf 11�FR�n�ff 1�/oi unr e�.49 a - fi — - 1o�I Rlunpff_pepthP8429'� A _ 4- I 4 I - 9--TcS.0mi o -C"5_ _I 7 6� I _t _t I_I t rI -1 _fi I � I -1 t I I I t- 1 -1 -_ 5� , - I CIA � I � 4- I4 � I � 4—/ _ _ _ II IIIIIIIIII 1L o �..�.. .. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 38 Summary for Link POA-1: 30" Pipe Inflow Area = 9.759 ac, 87.56% Impervious, Inflow Depth > 7.96" for 100-Year Cornell event Inflow = 81.16 cfs @ 12.09 hrs, Volume= 6.475 of Primary = 81.16 cfs @ 12.09 hrs, Volume= 6.475 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-1: 30" Pipe Hydrograph T I ❑Inflow 90_/ _ _ I❑Primary 85= 81.16 cfs fi 80 Inflow Area=9.7 75 Irt � l � fil 1tI 70 i _ _ 65 60 55. _ 50 3 45 FL 40 35. T 30 25 20 15 10 5 0 �..�..r../. /.... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 39 Summary for Link POA-2: 15" Pipe Inflow Area = 4.574 ac, 93.48% Impervious, Inflow Depth > 8.41" for 100-Year Cornell event Inflow = 38.82 cfs @ 12.09 hrs, Volume= 3.207 of Primary = 38.82 cfs @ 12.09 hrs, Volume= 3.207 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-2: 15" Pipe Hydrograph - 1 A 4 ❑Inflow i 42� �I 38.82 cfs + 0 Primary 40- 38 36� I E 34� � 32 4 t- I -4 4- 1 + 14 1 - 1 1 1 30 fi fi t- 11 t 28= � 26= � EIS L I III :EI ::I :E U_ 18- — � 4 � 1 _4 4_ 1-1 4_ 1 -4 � 1 - 4 1 -1 1- 18- �-- 16 — — — — — — — — — — — 10f I L EIS 1: I -1 1 1- 6 6� � 4. 2- 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 40 Summary for Link POA-3A: 24" Pipe Inflow Area = 2.320 ac, 87.26% Impervious, Inflow Depth > 8.05" for 100-Year Cornell event Inflow = 19.39 cfs @ 12.09 hrs, Volume= 1.556 of Primary = 19.39 cfs @ 12.09 hrs, Volume= 1.556 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-3A: 24" Pipe Hydrograph I ❑Inflow 21 1 A �Q rf �= 20� inflow Area=2.k 19�39 cfs fi pPrimary 19_ I EIS :E I 17E 1161�15_ � 14 fil fil 1 1 fit -1 t1— � 12 � Z 1711 :EI -1 L I 11- � 0 10 FL 9 7� I_ - - - - =1 - 1- 5 5� � I -1 LI —, E1 :1 1: 1 -1 1 1- 4� � 3 2- 1= 0° ......... ..... .... ... :.. ... .. .. ..�:..�:..�...�...�.... .... ...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Existing Type 111 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 41 Summary for Link POA-313: 18" Pipe Inflow Area = 1.721 ac, 93.08% Impervious, Inflow Depth > 8.29" for 100-Year Cornell event Inflow = 14.54 cfs @ 12.09 hrs, Volume= 1.189 of Primary = 14.54 cfs @ 12.09 hrs, Volume= 1.189 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-313: 18" Pipe Hydrograph fi l T 112 Primary 15� �—Inflow Area-1 .7 14�54 cfsow - — — 14' 1 -1 L 1 -1 L i I L I A L T 13� � 12�-/ T I T T I T T 1I T T T I T T I I T � 9� � — — - — — II4 I -4 1 -1 1- 0 3 6� 6 5�Z 1- 1 _T TIT T 1 T IT TIT T T I 4—/ — 3� � 1 � � I � fit T 1 - IT 2 �— l l 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Post-Redevelopment Hydrological Computations POA-3 18" Pipe a d 24" Pipe ASSI-2 POA-2 Subs rface Infi ation 15.4ipe System 2 HDPR-3B PR-3A PR-2 HD Parking Lot East Portion of Lot South Portion of Lot PR-1A North Portion of Lot PR-1 B HVMA Lot SSI-1 ubsurface Infiltration System 1 POA-1 30" Pipe SubCat Reach on Link Routing Diagram for The Arsenal Project-Proposed Prepared by RJO'Connell&Associates, Inc., Printed 6/14/2016 HydroCAD®10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC The Arsenal Project-Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 2 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentHDPR-3B: HD Parking Lot Runoff Area=66,885 sf 87.83% Impervious Runoff Depth>2.44" Tc=6.0 min CN=93 Runoff=4.17 cfs 0.313 of SubcatchmentPR-1A: North Portion of Runoff Area=393,607 sf 96.73% Impervious Runoff Depth>2.75" Tc=6.0 min CN=96 Runoff=26.48 cfs 2.069 of Subcatchment PR-1 B: HVMA Lot Runoff Area=116,176 sf 79.06% Impervious Runoff Depth>2.17" Tc=6.0 min CN=90 Runoff=6.56 cfs 0.482 of SubcatchmentPR-2: South Portion of Lot Runoff Area=57,681 sf 83.32% Impervious Runoff Depth>2.35" Tc=6.0 min CN=92 Runoff=3.49 cfs 0.259 of SubcatchmentPR-3A: East Portion of Lot Runoff Area=162,941 sf 96.59% Impervious Runoff Depth>2.85" Tc=6.0 min CN=97 Runoff=11.18 cfs 0.890 of Pond SSI-1: Subsurface Infiltration System Peak Elev=16.54' Storage=34,381 cf Inflow=33.05 cfs 2.550 of Discarded=5.99 cfs 2.548 of Primary=0.00 cfs 0.000 of Outflow=5.99 cfs 2.548 of Pond SSI-2: Subsurface Infiltration System Peak Elev=10.95' Storage=27,631 cf Inflow=15.34 cfs 1.203 of Discarded=0.58 cfs 0.706 of Primary=0.51 cfs 0.101 of Outflow=1.08 cfs 0.807 of Link POA-1: 30" Pipe Inflow=0.00 cfs 0.000 of Primary=0.00 cfs 0.000 of Link POA-2: 15" Pipe Inflow=3.49 cfs 0.259 of Primary=3.49 cfs 0.259 of Link POA-3: 18" Pipe and 24" Pipe Inflow=0.51 cfs 0.101 of Primary=0.51 cfs 0.101 of Total Runoff Area = 18.303 ac Runoff Volume = 4.012 of Average Runoff Depth = 2.63" 7.59% Pervious = 1.390 ac 92.41% Impervious = 16.914 ac The Arsenal Project-Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 3 Summary for Subcatchment HDPR-313: HD Parking Lot Runoff = 4.17 cfs @ 12.09 hrs, Volume= 0.313 af, Depth> 2.44" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 8,139 61 >75% Grass cover, Good, HSG B 58,746 98 Paved parkinq, HSG B 66,885 93 Weighted Average 8,139 12.17% Pervious Area 58,746 87.83% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment HDPR-313: HD Parking Lot Hydrograph - ❑Runoff cfs 4 I—Ty IIfiZ4-ti� 4.17 r 12�Year Cornell Rainfoll�IgO` Area=6 ,8�5 f4=ff,Volume�L-0.31 ;-'� Runoff Depth>2.44" T =�.0 min 3 � N--93 LL 2 o ..�..�..�..�.. ....�...,:.. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 4 Summary for Subcatchment PR-1A: North Portion of Lot Runoff = 26.48 cfs @ 12.09 hrs, Volume= 2.069 af, Depth> 2.75" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 12,883 39 >75% Grass cover, Good, HSG A 174,583 98 Roofs, HSG A 206,141 98 Paved parkinq, HSG A 393,607 96 Weighted Average 12,883 3.27% Pervious Area 380,724 96.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1A: North Portion of Lot Hydrograph .�� I ❑Runoff 28-_�/ � 11 26.48 cfs 26� - 24�-/12�Yoar ICornoll Railnfoll�3.?O" 22�'/_ unoff � Area=3 3,�07 sff fi —unoffVdu20�I n of 18—/ Ru_6o"4pttlh>Z7 ! � LTFF " 12� 10� � I -1 T 4� 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 5 Summary for Subcatchment PR-1 B: HVMA Lot Runoff = 6.56 cfs @ 12.09 hrs, Volume= 0.482 af, Depth> 2.17" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 24,326 61 >75% Grass cover, Good, HSG B 18,625 98 Roofs, HSG B 73,225 98 Paved parkinq, HSG B 116,176 90 Weighted Average 24,326 20.94% Pervious Area 91,850 79.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1 B: HVMA Lot + I Hydrograph �!— � � — 1 � — � ❑Runoff 7- 1 11 6.56 cfs Type III 24-h lr 6�-/J 2�Yoar'Cdrnoll Rainfoll�3.20"i 5-:A �un ff Area=116,17 sff unoff'VdlumeL0.48� of 1 1—Runoff Depth>2.17" - w 4 / 3 - TF=�.a min I I I I a 3� 2 1� 0 /:.../:... .. .. .. ..�...�.../:.../.... .... :..., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 6 Summary for Subcatchment PR-2: South Portion of Lot Runoff = 3.49 cfs @ 12.09 hrs, Volume= 0.259 af, Depth> 2.35" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 9,621 61 >75% Grass cover, Good, HSG B 40,578 98 Roofs, HSG B 7,482 98 Paved parkinq, HSG B 57,681 92 Weighted Average 9,621 16.68% Pervious Area 48,060 83.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-2: South Portion of Lot Hydrograph �I - ❑Runoff Type III 24-hi- I 13.49 cfs 3�1-2 1Y far'Cdr ll-Rai-nfoll=�3.p" �unpff Area-57,681 f LL unloff VolumeL0.125: of Runloff Depth>2.35" 2/mac,c- .0 min CN-921 .2 IIIIIIIII ' ( IIIII I � - - II ' Illll ' III o ,:...,. ../... .. ..�.../....�:...�:.........:.... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 7 Summary for Subcatchment PR-3A: East Portion of Lot Runoff = 11.18 cfs @ 12.09 hrs, Volume= 0.890 af, Depth> 2.85" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 5,559 61 >75% Grass cover, Good, HSG B 67,368 98 Roofs, HSG B 90,014 98 Paved parkinq, HSG B 162,941 97 Weighted Average 5,559 3.41% Pervious Area 157,382 96.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-3A: East Portion of Lot Hydrograph 12� 11 11.18 CfS ■Runoff T�� 11�24-h fi - 10� 2�YoarICorndll Railnfoll�3.?O" 9� u tIoff-ArlIes=162, 41ll stL — urYoff�dh�me-00 of N $ -luno"Opfh>2.8 ' --1 4- - 1 3 6� ��N 971 � I -I T rt t- I -I 3 o- :... :... '... .. .. ..�..�..�...r:...�:...�....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type /// 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 8 Summary for Pond SSI-1: Subsurface Infiltration System 1 Inflow Area = 11.703 ac, 92.70% Impervious, Inflow Depth > 2.62" for 2-Year Cornell event Inflow = 33.05 cfs @ 12.09 hrs, Volume= 2.550 of Outflow = 5.99 cfs @ 12.54 hrs, Volume= 2.548 af, Atten= 82%, Lag= 27.3 min Discarded = 5.99 cfs @ 12.54 hrs, Volume= 2.548 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 16.54' @ 12.54 hrs Surf.Area= 14,652 sf Storage= 34,381 cf Plug-Flow detention time= 43.1 min calculated for 2.548 of(100% of inflow) Center-of-Mass det. time= 42.7 min ( 822.4 - 779.8 ) Volume Invert Avail.Storage Storage Description #1A 12.00' 40,931 cf 66.00'W x 222.00'L x 13.00'H Field A 190,476 cf Overall - 88,150 cf Embedded = 102,326 cf x 40.0% Voids #2A 14.50' 88,150 cf CMP_Round 120 x 5 Inside #1 Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.00'L Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 62.00' Header x 78.43 sf x 2 = 9,724.7 cf Inside 129,080 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 22.50' 24.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 22.50' /22.45' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf #2 Discarded 12.00' 8.270 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 8.00' Discarded OutFlow Max=5.99 cfs @ 12.54 hrs HW=16.54' (Free Discharge) L2=Exfiltration ( Controls 5.99 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.00' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) The Arsenal Project-Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 9 Pond SSI-1: Subsurface Infiltration System 1 - Chamber Wizard Field A Chamber Model = CMP_Round 120 (Round Corrugated Metal Pipe) Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.001 Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 120.0" Wide + 36.0" Spacing = 156.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +180.00' Row Adjustment +10.00' Header x 2 = 220.00' Row Length +12.0" End Stone x 2 = 222.00' Base Length 5 Rows x 120.0" Wide + 36.0" Spacing x 4 + 24.0" Side Stone x 2 = 66.00' Base Width 30.0" Base + 120.0" Chamber Height + 6.0" Cover = 13.00' Field Height 5 Chambers x 1,568.5 cf +180.00' Row Adjustment x 78.43 sf x 5 Rows + 62.00' Header x 78.43 sf x 2 = 88,149.7 cf Chamber Storage 190,476.0 cf Field - 88,149.7 cf Chambers = 102,326.3 cf Stone x 40.0% Voids = 40,930.5 cf Stone Storage Chamber Storage + Stone Storage = 129,080.2 cf= 2.963 of Overall Storage Efficiency = 67.8% 5 Chambers 7,054.7 cy Field 3,789.9 cy Stone The Arsenal Project-Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 10 Pond SSI-1: Subsurface Infiltration System 1 Hydrograph 1-1 1 1— —+ �—1 ❑ Inflow � 133.05 CfS I __ outflow i �46v_Aue� 11A7b�a - l- — l - -l - o Primary 36' / / 34 � �'eald���1pe ii�dfi6.5 � rt rt - - — — - 32. 30 V / i Ttqr�l'-�I"q r i8qI - 28�/ 261 _ , /i I � � I� � I � I I J_ I� � I � �I 243 N 22V � — 20/ , /—I � 1 1 4- 1� � I4 3 18i /— LL16 V 14 12/ � /-1 t 1 1 films 10� 5.99 cfs - $� % �I T I 0.00 cfs 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type /// 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 11 Summary for Pond SSI-2: Subsurface Infiltration System 2 Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth > 2.74" for 2-Year Cornell event Inflow = 15.34 cfs @ 12.09 hrs, Volume= 1.203 of Outflow = 1.08 cfs @ 13.41 hrs, Volume= 0.807 af, Atten= 93%, Lag= 79.2 min Discarded = 0.58 cfs @ 13.41 hrs, Volume= 0.706 of Primary = 0.51 cfs @ 13.41 hrs, Volume= 0.101 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 10.95' @ 13.41 hrs Surf.Area= 14,107 sf Storage= 27,631 cf Plug-Flow detention time= 261.8 min calculated for 0.805 of(67% of inflow) Center-of-Mass det. time= 166.5 min ( 939.0 - 772.5 ) Volume Invert Avail.Storage Storage Description #1A 8.00' 18,850 cf 44.50'W x 317.00'L x 6.00'H Field A 84,639 cf Overall - 37,515 cf Embedded = 47,124 cf x 40.0% Voids #2A 8.50' 37,515 cf CMP_Round 60 x 6 Inside #1 Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 42.50' Header x 19.59 sf x 2 = 1,665.2 cf Inside 56,365 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #2 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/ Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #3 Discarded 8.00' 1.020 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 4.00' Discarded OutFlow Max=0.58 cfs @ 13.41 hrs HW=10.95' (Free Discharge) L3=Exfiltration ( Controls 0.58 cfs) Primary OutFlow Max=0.50 cfs @ 13.41 hrs HW=10.95' (Free Discharge) �__1=Culvert (Barrel Controls 0.25 cfs @ 1.95 fps) 2=Culvert (Barrel Controls 0.25 cfs @ 1.95 fps) The Arsenal Project-Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 12 Pond SSI-2: Subsurface Infiltration System 2 - Chamber Wizard Field A Chamber Model = CMP_Round 60 (Round Corrugated Metal Pipe) Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 60.0" Wide + 30.0" Spacing = 90.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +285.00' Row Adjustment +5.00' Header x 2 = 315.00' Row Length +12.0" End Stone x 2 = 317.00' Base Length 6 Rows x 60.0" Wide + 30.0" Spacing x 5 + 12.0" Side Stone x 2 = 44.50' Base Width 6.0" Base + 60.0" Chamber Height + 6.0" Cover = 6.00' Field Height 6 Chambers x 391.8 cf +285.00' Row Adjustment x 19.59 sf x 6 Rows + 42.50' Header x 19.59 sf x 2 = 37,514.9 cf Chamber Storage 84,639.0 cf Field - 37,514.9 cf Chambers = 47,124.1 cf Stone x 40.0% Voids = 18,849.7 cf Stone Storage Chamber Storage + Stone Storage = 56,364.5 cf= 1.294 of Overall Storage Efficiency = 66.6% 6 Chambers 3,134.8 cy Field 1,745.3 cy Stone The Arsenal Project-Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 13 Pond SSI-2: Subsurface Infiltration System 2 Hydrograph I T I- J I r- I El Inflow N `_, /��.� c �+1�5. El 34 outflow 17= / A H-FO' ii AI eii i5 �F7'Q ❑Primary 15 / Teal le v 3r0. 'rt - - - - - - - 14�;__/ / r$tOr49e:217634 IC#t rt l I _r I _1 fi I r_ l 13� / — 12: /-I T I-I T I -1 T _T 7 I I T 17 T -1 E-I ,9 Ii - -I - - - - - 6-V -IT 1-1 771 � � - TI7 TIC r 4 / �I T 7 1.08 cfs 3_ -661 2: 1 0.51 cfsl�Em_ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 14 Summary for Link POA-1: 30" Pipe Inflow Area = 11.703 ac, 92.70% Impervious, Inflow Depth = 0.00" for 2-Year Cornell event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-1: 30" Pipe Hydrograph �I 1 ❑Inflow ❑Primary Inflow Area=i 1 .703Iac N V 3 0 0.00 cfs 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 15 Summary for Link POA-2: 15" Pipe Inflow Area = 1.324 ac, 83.32% Impervious, Inflow Depth > 2.35" for 2-Year Cornell event Inflow = 3.49 cfs @ 12.09 hrs, Volume= 0.259 of Primary = 3.49 cfs @ 12.09 hrs, Volume= 0.259 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-2: 15" Pipe Hydrograph l l l l l l Inflow � 3.49 cfs � I ❑Primary Inilo�v Area-1 .3 I t 3 IIIIIII 2 3 0 LL 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 16 Summary for Link POA-3: 18" Pipe and 24" Pipe Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth = 0.23" for 2-Year Cornell event Inflow = 0.51 cfs @ 13.41 hrs, Volume= 0.101 of Primary = 0.51 cfs @ 13.41 hrs, Volume= 0.101 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-3: 18" Pipe and 24" Pipe Hydrograph � I4 � I � I � � � 4- 1 ❑Inflow 005 Inflow Area 5.276 0.51 cfs - ❑Primary 0.45-i'/ 0.35�-/ 3 i—°° 0.25�1/ 0.15-�/ — 0.05� 0 r..�..r..r..(.. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 17 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentHDPR-3B: HD Parking Lot Runoff Area=66,885 sf 87.83% Impervious Runoff Depth>4.10" Tc=6.0 min CN=93 Runoff=6.79 cfs 0.524 of SubcatchmentPR-1A: North Portion of Runoff Area=393,607 sf 96.73% Impervious Runoff Depth>4.43" Tc=6.0 min CN=96 Runoff=41.59 cfs 3.336 of Subcatchment PR-1 B: HVMA Lot Runoff Area=116,176 sf 79.06% Impervious Runoff Depth>3.78" Tc=6.0 min CN=90 Runoff=11.16 cfs 0.839 of SubcatchmentPR-2: South Portion of Lot Runoff Area=57,681 sf 83.32% Impervious Runoff Depth>3.99" Tc=6.0 min CN=92 Runoff=5.76 cfs 0.440 of SubcatchmentPR-3A: East Portion of Lot Runoff Area=162,941 sf 96.59% Impervious Runoff Depth>4.54" Tc=6.0 min CN=97 Runoff=17.38 cfs 1.417 of Pond SSI-1: Subsurface Infiltration System Peak Elev=18.97' Storage=63,702 cf Inflow=52.74 cfs 4.176 of Discarded=7.69 cfs 4.173 of Primary=0.00 cfs 0.000 of Outflow=7.69 cfs 4.173 of Pond SSI-2: Subsurface Infiltration System Peak Elev=11.79' Storage=37,088 cf Inflow=24.17 cfs 1.941 of Discarded=0.65 cfs 0.789 of Primary=6.69 cfs 0.681 of Outflow=7.34 cfs 1.470 of Link POA-1: 30" Pipe Inflow=0.00 cfs 0.000 of Primary=0.00 cfs 0.000 of Link POA-2: 15" Pipe Inflow=5.76 cfs 0.440 of Primary=5.76 cfs 0.440 of Link POA-3: 18" Pipe and 24" Pipe Inflow=6.69 cfs 0.681 of Primary=6.69 cfs 0.681 of Total Runoff Area = 18.303 ac Runoff Volume = 6.557 of Average Runoff Depth = 4.30" 7.59% Pervious = 1.390 ac 92.41% Impervious = 16.914 ac The Arsenal Project-Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 18 Summary for Subcatchment HDPR-3B: HD Parking Lot Runoff = 6.79 cfs @ 12.09 hrs, Volume= 0.524 af, Depth> 4.10" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 8,139 61 >75% Grass cover, Good, HSG B 58,746 98 Paved parkinq, HSG B 66,885 93 Weighted Average 8,139 12.17% Pervious Area 58,746 87.83% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment HDPR-3B: HD Parking Lot Hydrograph ❑Runoff 6.79 cfs 7_ Type III 24-hr 6_�,/1-1I9'fpar CornplTa1nfOI".W' Runoff Area=66,88T"24 s 5��­2unn ff'to�urr�e=0. af4 Runoff Depth)>4.I101' 3 4� i C =63 0 LL 1 o ../..1..�..�.. ....�.. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 19 Summary for Subcatchment PR-1A: North Portion of Lot Runoff = 41.59 cfs @ 12.09 hrs, Volume= 3.336 af, Depth> 4.43" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 12,883 39 >75% Grass cover, Good, HSG A 174,583 98 Roofs, HSG A 206,141 98 Paved parkinq, HSG A 393,607 96 Weighted Average 12,883 3.27% Pervious Area 380,724 96.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1A: North Portion of Lot Hydrograph ■ 46� — Runoff 44- — 41.59 cfs 40-—TJ_D1 IU�2�--h� 38 t�1P-Yea-lr-C hei�R f "01' — I __1 36-- — f—A — — — — — — — 32 I_Znoff Vdlin 3 7� 30_ �Iu6o"Opth>4 ., -1 4- 14 1 � - 28�I w 26_�_/ — — — — — — — — — 24 .O�mir>L rt f— fi - - fi — - - - 0 22' LL18- 1 1 - T I __� J_ 1-1 1 __1 16 - — 18 1 -7 T I CI _ EIS T _T —I - 6- — 4 ' 1 4 14 - 2 o` :... :... '... .. .. ..�..�..�...�:...�:...�....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 20 Summary for Subcatchment PR-1 B: HVMA Lot Runoff = 11.16 cfs @ 12.09 hrs, Volume= 0.839 af, Depth> 3.78" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 24,326 61 >75% Grass cover, Good, HSG B 18,625 98 Roofs, HSG B 73,225 98 Paved parkinq, HSG B 116,176 90 Weighted Average 24,326 20.94% Pervious Area 91,850 79.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1 B: HVMA Lot Hydrograph 12� 11 11.16 cfs ■Runoff Ty_ 11�24-h - 10� 1p-yeal- Coroel� Roinfa11�=4�901' 9�"/ unlIoff-ArlIea='rT6, 611 sfLL � i L _ �urYoff�dh�me=09 af N $ -lunloff Opth>3.7$" 6� �CFN9U ___in 2� 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 21 Summary for Subcatchment PR-2: South Portion of Lot Runoff = 5.76 cfs @ 12.09 hrs, Volume= 0.440 af, Depth> 3.99" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 9,621 61 >75% Grass cover, Good, HSG B 40,578 98 Roofs, HSG B 7,482 98 Paved parkinq, HSG B 57,681 92 Weighted Average 9,621 16.68% Pervious Area 48,060 83.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-2: South Portion of Lot Hydrograph �� I I _ _ ■Runoff 6�I Type III24�hr I I I 5.76 cfs S-,-/j-lQ-YiearCompll-fZalnf�l"•9V' I I t I I _ Runoff Area=57,681 sf Runoff'Volume=b.401af l l Rlunoff Depthl>3.I991' U Tc=6.0 min 3 � CN-92- I _ - LL 2�Z 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 22 Summary for Subcatchment PR-3A: East Portion of Lot Runoff = 17.38 cfs @ 12.09 hrs, Volume= 1.417 af, Depth> 4.54" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 5,559 61 >75% Grass cover, Good, HSG B 67,368 98 Roofs, HSG B 90,014 98 Paved parkinq, HSG B 162,941 97 Weighted Average 5,559 3.41% Pervious Area 157,382 96.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-3A: East Portion of Lot Hydrograph � I 1s� 11 � 17.38 cfs � 17- T�� 11�24--h� - - - 116 5 �P-Ye�l_h�R f� 01' 1 1 1 14� unoff�►rea- , 1 $ 13�� unof�dlulne-1.41 7 12 i-] uUrt6"Opth>4-5 " 1 -1 4- H _ I - U 11 _ Amin - 0 9 / 1.�97 LL 8 1-1 61 5=,_ I �- — I—I — — — — I — — — — I 1 — — —I - 31_ I 1 + � I I � + 1_I 1 I � 1= 0" ,....,:...,-....�:..�..�..�..�:.. ...�...,:...,....,.... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type /// 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 23 Summary for Pond SSI-1: Subsurface Infiltration System 1 Inflow Area = 11.703 ac, 92.70% Impervious, Inflow Depth > 4.28" for 10-Year Cornell event Inflow = 52.74 cfs @ 12.09 hrs, Volume= 4.176 of Outflow = 7.69 cfs @ 12.59 hrs, Volume= 4.173 af, Atten= 85%, Lag= 30.4 min Discarded = 7.69 cfs @ 12.59 hrs, Volume= 4.173 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 18.97' @ 12.59 hrs Surf.Area= 14,652 sf Storage= 63,702 cf Plug-Flow detention time= 69.2 min calculated for 4.164 of(100% of inflow) Center-of-Mass det. time= 68.6 min ( 836.7 - 768.2 ) Volume Invert Avail.Storage Storage Description #1A 12.00' 40,931 cf 66.00'W x 222.00'L x 13.00'H Field A 190,476 cf Overall - 88,150 cf Embedded = 102,326 cf x 40.0% Voids #2A 14.50' 88,150 cf CMP_Round 120 x 5 Inside #1 Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.00'L Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 62.00' Header x 78.43 sf x 2 = 9,724.7 cf Inside 129,080 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 22.50' 24.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 22.50' /22.45' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf #2 Discarded 12.00' 8.270 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 8.00' Discarded OutFlow Max=7.69 cfs @ 12.59 hrs HW=18.97' (Free Discharge) L2=Exfiltration ( Controls 7.69 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.00' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) The Arsenal Project-Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 24 Pond SSI-1: Subsurface Infiltration System 1 - Chamber Wizard Field A Chamber Model = CMP_Round 120 (Round Corrugated Metal Pipe) Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.001 Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 120.0" Wide + 36.0" Spacing = 156.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +180.00' Row Adjustment +10.00' Header x 2 = 220.00' Row Length +12.0" End Stone x 2 = 222.00' Base Length 5 Rows x 120.0" Wide + 36.0" Spacing x 4 + 24.0" Side Stone x 2 = 66.00' Base Width 30.0" Base + 120.0" Chamber Height + 6.0" Cover = 13.00' Field Height 5 Chambers x 1,568.5 cf +180.00' Row Adjustment x 78.43 sf x 5 Rows + 62.00' Header x 78.43 sf x 2 = 88,149.7 cf Chamber Storage 190,476.0 cf Field - 88,149.7 cf Chambers = 102,326.3 cf Stone x 40.0% Voids = 40,930.5 cf Stone Storage Chamber Storage + Stone Storage = 129,080.2 cf= 2.963 of Overall Storage Efficiency = 67.8% 5 Chambers 7,054.7 cy Field 3,789.9 cy Stone The Arsenal Project-Proposed Type 111 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 25 Pond SSI-1: Subsurface Infiltration System 1 Hydrograph I� 52.74 cfs El❑ inflow Outflow /r ❑Discarded Inflow Area=11 .703 a [IPrimary 55%/ i V Perak-E1e-V*U.97' 1 T I 1 T 17 50 L tgr�Jle=6��0��f� T _ 45� / 40�-/ T T T -f + y 35�-/ i 1 LL 25�-/ / I T T -4 20�-/ / I T I 15 / 7.69 cfs A. 0.00 cfs 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type /// 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 26 Summary for Pond SSI-2: Subsurface Infiltration System 2 Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth > 4.41" for 10-Year Cornell event Inflow = 24.17 cfs @ 12.09 hrs, Volume= 1.941 of Outflow = 7.34 cfs @ 12.40 hrs, Volume= 1.470 af, Atten= 70%, Lag= 19.1 min Discarded = 0.65 cfs @ 12.41 hrs, Volume= 0.789 of Primary = 6.69 cfs @ 12.40 hrs, Volume= 0.681 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 11.79' @ 12.41 hrs Surf.Area= 14,107 sf Storage= 37,088 cf Plug-Flow detention time= 180.8 min calculated for 1.467 of(76% of inflow) Center-of-Mass det. time= 97.7 min ( 859.6 - 761.9 ) Volume Invert Avail.Storage Storage Description #1A 8.00' 18,850 cf 44.50'W x 317.00'L x 6.00'H Field A 84,639 cf Overall - 37,515 cf Embedded = 47,124 cf x 40.0% Voids #2A 8.50' 37,515 cf CMP_Round 60 x 6 Inside #1 Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 42.50' Header x 19.59 sf x 2 = 1,665.2 cf Inside 56,365 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #2 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/ Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #3 Discarded 8.00' 1.020 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 4.00' Discarded OutFlow Max=0.65 cfs @ 12.41 hrs HW=11.79' (Free Discharge) L3=Exfiltration ( Controls 0.65 cfs) Primary OutFlow Max=6.68 cfs @ 12.40 hrs HW=11.79' (Free Discharge) �__1=Culvert (Barrel Controls 3.34 cfs @ 3.40 fps) 2=Culvert (Barrel Controls 3.34 cfs @ 3.40 fps) The Arsenal Project-Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 27 Pond SSI-2: Subsurface Infiltration System 2 - Chamber Wizard Field A Chamber Model = CMP_Round 60 (Round Corrugated Metal Pipe) Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 60.0" Wide + 30.0" Spacing = 90.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +285.00' Row Adjustment +5.00' Header x 2 = 315.00' Row Length +12.0" End Stone x 2 = 317.00' Base Length 6 Rows x 60.0" Wide + 30.0" Spacing x 5 + 12.0" Side Stone x 2 = 44.50' Base Width 6.0" Base + 60.0" Chamber Height + 6.0" Cover = 6.00' Field Height 6 Chambers x 391.8 cf +285.00' Row Adjustment x 19.59 sf x 6 Rows + 42.50' Header x 19.59 sf x 2 = 37,514.9 cf Chamber Storage 84,639.0 cf Field - 37,514.9 cf Chambers = 47,124.1 cf Stone x 40.0% Voids = 18,849.7 cf Stone Storage Chamber Storage + Stone Storage = 56,364.5 cf= 1.294 of Overall Storage Efficiency = 66.6% 6 Chambers 3,134.8 cy Field 1,745.3 cy Stone The Arsenal Project-Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 28 Pond SSI-2: Subsurface Infiltration System 2 Hydrograph �I1 4- I -4 �— I 4 11 4- I� 4 -4 24.17 cfs — i outflow / >Aln�offl A�e�5.2 f"l l I I 1 1 1 ;Primaryed 26� / 24�Z / /' Na"I eve--" ."'-f _+ 1 J_ I _f �_ 22� / L$t_OrOAe�37J8L Of _L 1 1 1 1� L _L L- 20�/ / LL 12 / �I T T 1 -17.34cfs T I� FI 186.69 cfs 4 __4 4 4 — 4— / 2 0 �...(...�:...�....,. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 29 Summary for Link POA-1: 30" Pipe Inflow Area = 11.703 ac, 92.70% Impervious, Inflow Depth = 0.00" for 10-Year Cornell event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-1: 30" Pipe Hydrograph �I 1 ❑Inflow ❑Primary Inflow Area=11 .70iac N V 3 0 0.00 cfs 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 30 Summary for Link POA-2: 15" Pipe Inflow Area = 1.324 ac, 83.32% Impervious, Inflow Depth > 3.99" for 10-Year Cornell event Inflow = 5.76 cfs @ 12.09 hrs, Volume= 0.440 of Primary = 5.76 cfs @ 12.09 hrs, Volume= 0.440 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-2: 15" Pipe Hydrograph ❑Inflow 5.76 cfs I D Primary Inflow Area=1 .3 5� _ IIIIIIIIIII IIIIIIIIIII 4� 111111111 IIIIIIIIIII 'FI FI � T 7 FI � I � 0 3—� I—IA LI -1 LI 2 IIIIIIII IIIlIl 1 - I o .... ... .... .. .. .. ..1... :... ... ....�.... ....,�........... .. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 31 Summary for Link POA-3: 18" Pipe and 24" Pipe Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth = 1.55" for 10-Year Cornell event Inflow = 6.69 cfs @ 12.40 hrs, Volume= 0.681 of Primary = 6.69 cfs @ 12.40 hrs, Volume= 0.681 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-3: 18" Pipe and 24" Pipe Hydrograph �I Inflow 6 ❑Primary .69 cfs l FI I � fil 5 � I __4 I - 4 l l l l l l l l l I 3 � — 0 1� - I o ..�../...�.. ....�....,. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 32 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentHDPR-3B: HD Parking Lot Runoff Area=66,885 sf 87.83% Impervious Runoff Depth>5.38" Tc=6.0 min CN=93 Runoff=8.77 cfs 0.688 of SubcatchmentPR-1A: North Portion of Runoff Area=393,607 sf 96.73% Impervious Runoff Depth>5.72" Tc=6.0 min CN=96 Runoff=53.04 cfs 4.309 of Subcatchment PR-1 B: HVMA Lot Runoff Area=116,176 sf 79.06% Impervious Runoff Depth>5.04" Tc=6.0 min CN=90 Runoff=14.65 cfs 1.120 of SubcatchmentPR-2: South Portion of Lot Runoff Area=57,681 sf 83.32% Impervious Runoff Depth>5.26" Tc=6.0 min CN=92 Runoff=7.47 cfs 0.581 of SubcatchmentPR-3A: East Portion of Lot Runoff Area=162,941 sf 96.59% Impervious Runoff Depth>5.84" Tc=6.0 min CN=97 Runoff=22.09 cfs 1.820 of Pond SSI-1: Subsurface Infiltration System Peak EIev=20.89' Storage=87,790 cf Inflow=67.68 cfs 5.429 of Discarded=9.04 cfs 5.425 of Primary=0.00 cfs 0.000 of Outflow=9.04 cfs 5.425 of Pond SSI-2: Subsurface Infiltration System Peak EIev=12.37' Storage=43,368 cf Inflow=30.86 cfs 2.508 of Discarded=0.70 cfs 0.838 of Primary=12.74 cfs 1.158 of Outflow=13.44 cfs 1.996 of Link POA-1: 30" Pipe Inflow=0.00 cfs 0.000 of Primary=0.00 cfs 0.000 of Link POA-2: 15" Pipe Inflow=7.47 cfs 0.581 of Primary=7.47 cfs 0.581 of Link POA-3: 18" Pipe and 24" Pipe Inflow=12.74 cfs 1.158 of Primary=12.74 cfs 1.158 of Total Runoff Area = 18.303 ac Runoff Volume = 8.518 of Average Runoff Depth = 5.58" 7.59% Pervious = 1.390 ac 92.41% Impervious = 16.914 ac The Arsenal Project-Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 33 Summary for Subcatchment HDPR-313: HD Parking Lot Runoff = 8.77 cfs @ 12.09 hrs, Volume= 0.688 af, Depth> 5.38" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 8,139 61 >75% Grass cover, Good, HSG B 58,746 98 Paved parkinq, HSG B 66,885 93 Weighted Average 8,139 12.17% Pervious Area 58,746 87.83% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment HDPR-313: HD Parking Lot Hydrograph - ❑Runoff 9_�'Z l � 8.77 cfs I T pe III 24 hr 8-�-/1 2�-Ypar Cornell II2aiInfOII=16.2p" -Runoff-Area=6"8�f Runoff Volume=b.6881af 6-:-/'l Runoff Pepthh5.1381' LL 4� 3� 2-1 - 1-_ 0 (..�..�..�../:.../....%.. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 34 Summary for Subcatchment PR-1A: North Portion of Lot Runoff = 53.04 cfs @ 12.09 hrs, Volume= 4.309 af, Depth> 5.72" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 12,883 39 >75% Grass cover, Good, HSG A 174,583 98 Roofs, HSG A 206,141 98 Paved parkinq, HSG A 393,607 96 Weighted Average 12,883 3.27% Pervious Area 380,724 96.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1A: North Portion of Lot Hydrograph _ _ O Runoff 55�'/ 53.04 cfs -TYp� I1-i-2"r - 50L I_25�ea�Clornell Rainfa11�6�201 4 1 - 45�_ unoff ArIea=393 60711 sff� 40� �unoff�Vdlu�ne=4.309 of 35-�-/1 Rluno"4pth>_$_.7 " 3 30=�� - .0—min - c 25 - 20=-'/ 10� o- :... :... '... ... .. ..�..�..�...r:...�:...�....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 35 Summary for Subcatchment PR-1 B: HVMA Lot Runoff = 14.65 cfs @ 12.09 hrs, Volume= 1.120 af, Depth> 5.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 24,326 61 >75% Grass cover, Good, HSG B 18,625 98 Roofs, HSG B 73,225 98 Paved parkinq, HSG B 116,176 90 Weighted Average 24,326 20.94% Pervious Area 91,850 79.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1 B: HVMA Lot Hydrograph 16�1 � T i � ❑Runoff 15 IT`_pe JU 24.h� — 14.65 cfs — - 14� Y 13= I25--yea-r Cior0eTl[R�nfa- ="0l'_ _ _-1 T_ —1 _F 1 _- _ ,2 T uoffArlIea16, 1l sf4 + 11_ unoff V u V76 0 a 1oT I-i uMT6ff Otlh>_5-0 " T - U 9- 0 8� '0— — T TT T TT T T TT LL 7✓ 6� T T T TT fi TT T T TT 2✓ — ,�' 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 36 Summary for Subcatchment PR-2: South Portion of Lot Runoff = 7.47 cfs @ 12.09 hrs, Volume= 0.581 af, Depth> 5.26" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 9,621 61 >75% Grass cover, Good, HSG B 40,578 98 Roofs, HSG B 7,482 98 Paved parkinq, HSG B 57,681 92 Weighted Average 9,621 16.68% Pervious Area 48,060 83.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-2: South Portion of Lot Hydrograph 8� ■Runoff 7.47 cfs - -Type 11V24-hrl 7� 2g-Year Cornell Rainfall=6.20" 6-,/ -RunQff-Area=57,68"f Runbff Volume=b.518l laf 5� Runoff Depth>5.261' Tc=6.0 min 4� CN=J2 rt l I � fil � I rt l I � .2 2- 1� 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 37 Summary for Subcatchment PR-3A: East Portion of Lot Runoff = 22.09 cfs @ 12.09 hrs, Volume= 1.820 af, Depth> 5.84" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 5,559 61 >75% Grass cover, Good, HSG B 67,368 98 Roofs, HSG B 90,014 98 Paved parkinq, HSG B 162,941 97 Weighted Average 5,559 3.41% Pervious Area 157,382 96.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-3A: East Portion of Lot Hydrograph 24" - — — — — — —I — ■Runoff 23/ 1 22.09 cfs 22�LT7 pe l U 24 � 1— — 21 — 20/i-25-yea�I he�R fai�--"o1' 4 1 + 1 I - 19_� — 17% ` ° ealI 1 2, 1ll T _1 E 7 T I E I � 16 luno=luin— e-1.—0 a - 15/H�lunoffl� pt#� H �� 4 L + w 14�— — — 13 _ .o ,in- 3 12 N==97 — M 11 — — 100 1 + 1 -1 1 --1 t 1 1 t__ 1 -1 - 6 — — — — 4 t 2 ; 4 T - 1 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type /// 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 38 Summary for Pond SSI-1: Subsurface Infiltration System 1 Inflow Area = 11.703 ac, 92.70% Impervious, Inflow Depth > 5.57" for 25-Year Cornell event Inflow = 67.68 cfs @ 12.09 hrs, Volume= 5.429 of Outflow = 9.04 cfs @ 12.62 hrs, Volume= 5.425 af, Atten= 87%, Lag= 32.0 min Discarded = 9.04 cfs @ 12.62 hrs, Volume= 5.425 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 20.89' @ 12.62 hrs Surf.Area= 14,652 sf Storage= 87,790 cf Plug-Flow detention time= 86.8 min calculated for 5.414 of(100% of inflow) Center-of-Mass det. time= 86.1 min ( 848.6 - 762.5 ) Volume Invert Avail.Storage Storage Description #1A 12.00' 40,931 cf 66.00'W x 222.00'L x 13.00'H Field A 190,476 cf Overall - 88,150 cf Embedded = 102,326 cf x 40.0% Voids #2A 14.50' 88,150 cf CMP_Round 120 x 5 Inside #1 Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.00'L Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 62.00' Header x 78.43 sf x 2 = 9,724.7 cf Inside 129,080 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 22.50' 24.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 22.50' /22.45' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf #2 Discarded 12.00' 8.270 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 8.00' Discarded OutFlow Max=9.04 cfs @ 12.62 hrs HW=20.89' (Free Discharge) L2=Exfiltration ( Controls 9.04 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.00' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) The Arsenal Project-Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 39 Pond SSI-1: Subsurface Infiltration System 1 - Chamber Wizard Field A Chamber Model = CMP_Round 120 (Round Corrugated Metal Pipe) Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.001 Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 120.0" Wide + 36.0" Spacing = 156.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +180.00' Row Adjustment +10.00' Header x 2 = 220.00' Row Length +12.0" End Stone x 2 = 222.00' Base Length 5 Rows x 120.0" Wide + 36.0" Spacing x 4 + 24.0" Side Stone x 2 = 66.00' Base Width 30.0" Base + 120.0" Chamber Height + 6.0" Cover = 13.00' Field Height 5 Chambers x 1,568.5 cf +180.00' Row Adjustment x 78.43 sf x 5 Rows + 62.00' Header x 78.43 sf x 2 = 88,149.7 cf Chamber Storage 190,476.0 cf Field - 88,149.7 cf Chambers = 102,326.3 cf Stone x 40.0% Voids = 40,930.5 cf Stone Storage Chamber Storage + Stone Storage = 129,080.2 cf= 2.963 of Overall Storage Efficiency = 67.8% 5 Chambers 7,054.7 cy Field 3,789.9 cy Stone The Arsenal Project-Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 40 Pond SSI-1: Subsurface Infiltration System 1 Hydrograph X//z .68 CfS ❑ Inflow 67 Outflow �64o� A��� 1' / b'3ra ❑Discarded 75- El Primary 70—/ FPdak- leV*20.8T -4 4 1 L I 65�/ 601/ / — glag 71 j _qV[ L 1 1 L I L L _L L_ 55 / 50� / ' T L L 7 L L 45. 1t1-1 F 40�1/ / 30 25 i 15 / 9.04 cfs 10: / 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type /// 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 41 Summary for Pond SSI-2: Subsurface Infiltration System 2 Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth > 5.71" for 25-Year Cornell event Inflow = 30.86 cfs @ 12.09 hrs, Volume= 2.508 of Outflow = 13.44 cfs @ 12.28 hrs, Volume= 1.996 af, Atten= 56%, Lag= 11.4 min Discarded = 0.70 cfs @ 12.28 hrs, Volume= 0.838 of Primary = 12.74 cfs @ 12.28 hrs, Volume= 1.158 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 12.37' @ 12.28 hrs Surf.Area= 14,107 sf Storage= 43,368 cf Plug-Flow detention time= 152.6 min calculated for 1.991 of(79% of inflow) Center-of-Mass det. time= 76.5 min ( 833.2 - 756.7 ) Volume Invert Avail.Storage Storage Description #1A 8.00' 18,850 cf 44.50'W x 317.00'L x 6.00'H Field A 84,639 cf Overall - 37,515 cf Embedded = 47,124 cf x 40.0% Voids #2A 8.50' 37,515 cf CMP_Round 60 x 6 Inside #1 Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 42.50' Header x 19.59 sf x 2 = 1,665.2 cf Inside 56,365 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #2 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/ Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #3 Discarded 8.00' 1.020 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 4.00' Discarded OutFlow Max=0.70 cfs @ 12.28 hrs HW=12.37' (Free Discharge) L3=Exfiltration ( Controls 0.70 cfs) Primary OutFlow Max=12.71 cfs @ 12.28 hrs HW=12.37' (Free Discharge) �__1=Culvert (Barrel Controls 6.35 cfs @ 4.04 fps) 2=Culvert (Barrel Controls 6.35 cfs @ 4.04 fps) The Arsenal Project-Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 42 Pond SSI-2: Subsurface Infiltration System 2 - Chamber Wizard Field A Chamber Model = CMP_Round 60 (Round Corrugated Metal Pipe) Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 60.0" Wide + 30.0" Spacing = 90.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +285.00' Row Adjustment +5.00' Header x 2 = 315.00' Row Length +12.0" End Stone x 2 = 317.00' Base Length 6 Rows x 60.0" Wide + 30.0" Spacing x 5 + 12.0" Side Stone x 2 = 44.50' Base Width 6.0" Base + 60.0" Chamber Height + 6.0" Cover = 6.00' Field Height 6 Chambers x 391.8 cf +285.00' Row Adjustment x 19.59 sf x 6 Rows + 42.50' Header x 19.59 sf x 2 = 37,514.9 cf Chamber Storage 84,639.0 cf Field - 37,514.9 cf Chambers = 47,124.1 cf Stone x 40.0% Voids = 18,849.7 cf Stone Storage Chamber Storage + Stone Storage = 56,364.5 cf= 1.294 of Overall Storage Efficiency = 66.6% 6 Chambers 3,134.8 cy Field 1,745.3 cy Stone The Arsenal Project-Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 43 Pond SSI-2: Subsurface Infiltration System 2 + Hydrograph + � I 1-1 t— I I —r I -1 T —t ■Inflow 30. ■Outflow + - Discarded34- /__IAo�1 A�e 5.��6� — ■Primary 30 / I��al�— -v — — — — — - — — - - 28-_�/ /—$toroigez4"68 I ,t rt 1 1 _r 1 _1 fi I �I - 26�;_/22% — - — I— — � 20�' / /— I T 1 1 -r1 -1 fi rt I � I� filrt �I - 18; / �— 13.44 cfs — o 1st / T � 1a / f— 12.74 cfs 10 / 8:/ / � I 4= 2� 0- ...�...�...�:... ......... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 44 Summary for Link POA-1: 30" Pipe Inflow Area = 11.703 ac, 92.70% Impervious, Inflow Depth = 0.00" for 25-Year Cornell event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-1: 30" Pipe Hydrograph �I 1 ❑Inflow ❑Primary Inflow Area=11 .70iac N V 3 0 0.00 cfs 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 45 Summary for Link POA-2: 15" Pipe Inflow Area = 1.324 ac, 83.32% Impervious, Inflow Depth > 5.26" for 25-Year Cornell event Inflow = 7.47 cfs @ 12.09 hrs, Volume= 0.581 of Primary = 7.47 cfs @ 12.09 hrs, Volume= 0.581 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-2: 15" Pipe Hydrograph �i I I -� I I ❑Inflow 7.47 cfs ❑Primary 11 Inflow Area=1 .3 6� IIIIIIIIII 5� IIIIIIIIII N c 4� ( IIIIIIIIII FL11771 � 71771 2� 0. 1-� 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 46 Summary for Link POA-3: 18" Pipe and 24" Pipe Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth = 2.63" for 25-Year Cornell event Inflow = 12.74 cfs @ 12.28 hrs, Volume= 1.158 of Primary = 12.74 cfs @ 12.28 hrs, Volume= 1.158 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-3: 18" Pipe and 24" Pipe Hydrograph 14 17 7 I❑Pilmary� 13� Inflow Area=5.271.12.74 cfs 12� � 3 7 0 5� 3— 2L' 13-/ 0- -..�..�..�.././...�...I ... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 47 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentHDPR-3B: HD Parking Lot Runoff Area=66,885 sf 87.83% Impervious Runoff Depth>8.05" Tc=6.0 min CN=93 Runoff=12.84 cfs 1.030 of SubcatchmentPR-1A: North Portion of Runoff Area=393,607 sf 96.73% Impervious Runoff Depth>8.41" Tc=6.0 min CN=96 Runoff=76.69 cfs 6.335 of Subcatchment PR-1 B: HVMA Lot Runoff Area=116,176 sf 79.06% Impervious Runoff Depth>7.69" Tc=6.0 min CN=90 Runoff=21.81 cfs 1.709 of SubcatchmentPR-2: South Portion of Lot Runoff Area=57,681 sf 83.32% Impervious Runoff Depth>7.93" Tc=6.0 min CN=92 Runoff=11.00 cfs 0.875 of SubcatchmentPR-3A: East Portion of Lot Runoff Area=162,941 sf 96.59% Impervious Runoff Depth>8.53" Tc=6.0 min CN=97 Runoff=31.85 cfs 2.660 of Pond SSI-1: Subsurface Infiltration Peak Elev=24.87' Storage=128,323 cf Inflow=98.50 cfs 8.044 of Discarded=11.83 cfs 7.479 of Primary=13.43 cfs 0.559 of Outflow=25.26 cfs 8.039 of Pond SSI-2: Subsurface Infiltration System Peak Elev=13.95' Storage=56,105 cf Inflow=44.69 cfs 3.690 of Discarded=0.83 cfs 0.916 of Primary=21.26 cfs 2.208 of Outflow=22.09 cfs 3.123 of Link POA-1: 30" Pipe Inflow=13.43 cfs 0.559 of Primary=13.43 cfs 0.559 of Link POA-2: 15" Pipe Inflow=11.00 cfs 0.875 of Primary=11.00 cfs 0.875 of Link POA-3: 18" Pipe and 24" Pipe Inflow=21.26 cfs 2.208 of Primary=21.26 cfs 2.208 of Total Runoff Area = 18.303 ac Runoff Volume = 12.610 of Average Runoff Depth = 8.27" 7.59% Pervious = 1.390 ac 92.41% Impervious = 16.914 ac The Arsenal Project-Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 48 Summary for Subcatchment HDPR-313: HD Parking Lot Runoff = 12.84 cfs @ 12.09 hrs, Volume= 1.030 af, Depth> 8.05" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 8,139 61 >75% Grass cover, Good, HSG B 58,746 98 Paved parkinq, HSG B 66,885 93 Weighted Average 8,139 12.17% Pervious Area 58,746 87.83% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment HDPR-313: HD Parking Lot Hydrograph 14: 12.84 cfs ❑Runoff 11� 7Qr0myea_r porhell Ryoinfa1 &PO" unofF_4r a=66,885_sf 10- �n�ff�Loi ume=1.0�0 1af-I N $ Iunpff_pe"8_05'� -k- v � Tc-6.0 T i � T 7= C"= 3 FL 5� 4-`/ 3� 2� 1� o= ... ..�..�..,. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 49 Summary for Subcatchment PR-1A: North Portion of Lot Runoff = 76.69 cfs @ 12.09 hrs, Volume= 6.335 af, Depth> 8.41" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 12,883 39 >75% Grass cover, Good, HSG A 174,583 98 Roofs, HSG A 206,141 98 Paved parkinq, HSG A 393,607 96 Weighted Average 12,883 3.27% Pervious Area 380,724 96.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1A: North Portion of Lot Hydrograph 85� i —1 -r- t— - — - O Runoff 80- 76.69 cfs _ —I 75� T�p� III 24I h r 1 _� 70=/I 190-Y( Cornell R infa11�8._0'J 4 4- 1 - 65?/ _Run Ioff_14_r a=393,6Q f - 6o�-Rlu -ff�F-i ume=6.3135 -1 -1 L 1 -1 1 -1 L I - 5o?/ Ru"fF­Pepth>8.4V- rt T_ 17 T 7 7 T_ 1 45 /-Tc-6.0 min - 0 40_�/I CN=96 fi rt - " 35-�/1— 1 ­4 1 1 4 �- 1 -� - 30?/_ _ 25-�/L I � L 1 1 LI -1 L - I _L LIB 20�'/ _ 15�,/I -1 T_ 1 --T 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 50 Summary for Subcatchment PR-1 B: HVMA Lot Runoff = 21.81 cfs @ 12.09 hrs, Volume= 1.709 af, Depth> 7.69" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 24,326 61 >75% Grass cover, Good, HSG B 18,625 98 Roofs, HSG B 73,225 98 Paved parkinq, HSG B 116,176 90 Weighted Average 24,326 20.94% Pervious Area 91,850 79.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1 B: HVMA Lot Hydrograph 24�� �_ �_ — I _ _� — �_ i ■Runoff 23/— _I -- 21.81 cfs - 22�kT� e 111*24I Kr 1 4 — - 20/ 1 90-year�goroel�Rf8_-�O'1 1- 19 18/-Runoff_Ar a=1 17/ ff�lto� .7�9 f :T — - 16l - 15�I RM"ff-pe P�9'� fi t 1 _t 1— I � 13/I�C .0�In - - ° 11/ - LL '9 _ I fi l I rt f I fi l I — — 1-1 — - l I 6 — — — — 4 2 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 51 Summary for Subcatchment PR-2: South Portion of Lot Runoff = 11.00 cfs @ 12.09 hrs, Volume= 0.875 af, Depth> 7.93" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 9,621 61 >75% Grass cover, Good, HSG B 40,578 98 Roofs, HSG B 7,482 98 Paved parkinq, HSG B 57,681 92 Weighted Average 9,621 16.68% Pervious Area 48,060 83.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-2: South Portion of Lot Hydrograph �I 12- ❑Runoff � � � � 11.00 cfs T —� 111 24 h r 10�1 1 90-yeor porhell Roin fall�&PO'J 9�-Runoff7�r a=57,681 sf — - $��R�rt�fftoIame=0.815 aft Tc=6.0 min _ U - - 2�- o- :... :"... .. .. ..�..�..�...r:...�:...�....,... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 52 Summary for Subcatchment PR-3A: East Portion of Lot Runoff = 31.85 cfs @ 12.09 hrs, Volume= 2.660 af, Depth> 8.53" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 5,559 61 >75% Grass cover, Good, HSG B 67,368 98 Roofs, HSG B 90,014 98 Paved parkinq, HSG B 162,941 97 Weighted Average 5,559 3.41% Pervious Area 157,382 96.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-3A: East Portion of Lot Hydrograph �— � � — � — � - ❑Runoff 34_ 31.85 cfs 32���� &24 hr 30 28: j 19"eor Cornell Rainfall=8.90'1 -t t- I -1 -r I I —I _Runoff7Ar a=162,941 f 24��Rl,n�ff 1V/ollunie=2.6r 01 — - 22�_/�_Rlu"fiff_pe P8.53" 14 I w 20, -Tc=6.0-mi n - .2 T T -1 T LIB I L -i LIT 12�_ 6 �I 2 fi - i o :... .... ../... ..�..�..�...r:...�:...�....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type /// 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 53 Summary for Pond SSI-1: Subsurface Infiltration System 1 Inflow Area = 11.703 ac, 92.70% Impervious, Inflow Depth > 8.25" for 100-Year Cornell event Inflow = 98.50 cfs @ 12.09 hrs, Volume= 8.044 of Outflow = 25.26 cfs @ 12.46 hrs, Volume= 8.039 af, Atten= 74%, Lag= 22.1 min Discarded = 11.83 cfs @ 12.46 hrs, Volume= 7.479 of Primary = 13.43 cfs @ 12.46 hrs, Volume= 0.559 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 24.87' @ 12.46 hrs Surf.Area= 14,652 sf Storage= 128,323 cf Plug-Flow detention time= 98.7 min calculated for 8.022 of(100% of inflow) Center-of-Mass det. time= 98.0 min ( 852.7 - 754.7 ) Volume Invert Avail.Storage Storage Description #1A 12.00' 40,931 cf 66.00'W x 222.00'L x 13.00'H Field A 190,476 cf Overall - 88,150 cf Embedded = 102,326 cf x 40.0% Voids #2A 14.50' 88,150 cf CMP_Round 120 x 5 Inside #1 Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.00'L Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 62.00' Header x 78.43 sf x 2 = 9,724.7 cf Inside 129,080 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 22.50' 24.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 22.50' /22.45' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf #2 Discarded 12.00' 8.270 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 8.00' Discarded OutFlow Max=11.83 cfs @ 12.46 hrs HW=24.86' (Free Discharge) L2=Exfiltration ( Controls 11.83 cfs) Primary OutFlow Max=13.39 cfs @ 12.46 hrs HW=24.86' (Free Discharge) L1=Culvert (Barrel Controls 13.39 cfs @ 4.55 fps) The Arsenal Project-Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 54 Pond SSI-1: Subsurface Infiltration System 1 - Chamber Wizard Field A Chamber Model = CMP_Round 120 (Round Corrugated Metal Pipe) Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.001 Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 120.0" Wide + 36.0" Spacing = 156.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +180.00' Row Adjustment +10.00' Header x 2 = 220.00' Row Length +12.0" End Stone x 2 = 222.00' Base Length 5 Rows x 120.0" Wide + 36.0" Spacing x 4 + 24.0" Side Stone x 2 = 66.00' Base Width 30.0" Base + 120.0" Chamber Height + 6.0" Cover = 13.00' Field Height 5 Chambers x 1,568.5 cf +180.00' Row Adjustment x 78.43 sf x 5 Rows + 62.00' Header x 78.43 sf x 2 = 88,149.7 cf Chamber Storage 190,476.0 cf Field - 88,149.7 cf Chambers = 102,326.3 cf Stone x 40.0% Voids = 40,930.5 cf Stone Storage Chamber Storage + Stone Storage = 129,080.2 cf= 2.963 of Overall Storage Efficiency = 67.8% 5 Chambers 7,054.7 cy Field 3,789.9 cy Stone The Arsenal Project-Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paae 55 Pond SSI-1: Subsurface Infiltration System 1 Hydrograph :T - /� 98.50 cfs _ ❑ Inflow / /�n6oWl�-/Y _47 A3TAc - - - - ❑Discarded 110_ / �-� - El Primary 105? {� 90% 2�:cfs t :r I I - 85 V / / — 80, / — - - 751 / �TI + __1 +_ 14 4- 1 4 1 + 70V / — — so i �I - - - - - - -1 - - L I - - 3 55� / LL 50/ 45-:/' / — 25.26 cfs r I 35 30f / - 25V 1 44 n 20/ / 13.43 cfs 15 / 10 ; 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type /// 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 56 Summary for Pond SSI-2: Subsurface Infiltration System 2 Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth > 8.39" for 100-Year Cornell event Inflow = 44.69 cfs @ 12.09 hrs, Volume= 3.690 of Outflow = 22.09 cfs @ 12.24 hrs, Volume= 3.123 af, Atten= 51%, Lag= 9.3 min Discarded = 0.83 cfs @ 12.24 hrs, Volume= 0.916 of Primary = 21.26 cfs @ 12.24 hrs, Volume= 2.208 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 13.95' @ 12.24 hrs Surf.Area= 14,107 sf Storage= 56,105 cf Plug-Flow detention time= 126.5 min calculated for 3.117 of(84% of inflow) Center-of-Mass det. time= 61.6 min ( 811.5 - 749.9 ) Volume Invert Avail.Storage Storage Description #1A 8.00' 18,850 cf 44.50'W x 317.00'L x 6.00'H Field A 84,639 cf Overall - 37,515 cf Embedded = 47,124 cf x 40.0% Voids #2A 8.50' 37,515 cf CMP_Round 60 x 6 Inside #1 Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 42.50' Header x 19.59 sf x 2 = 1,665.2 cf Inside 56,365 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #2 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/ Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #3 Discarded 8.00' 1.020 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 4.00' Discarded OutFlow Max=0.83 cfs @ 12.24 hrs HW=13.95' (Free Discharge) L3=Exfiltration ( Controls 0.83 cfs) Primary OutFlow Max=21.23 cfs @ 12.24 hrs HW=13.95' (Free Discharge) �11=Culvert (Inlet Controls 10.61 cfs @ 6.01 fps) 2=Culvert (Inlet Controls 10.61 cfs @ 6.01 fps) The Arsenal Project-Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 57 Pond SSI-2: Subsurface Infiltration System 2 - Chamber Wizard Field A Chamber Model = CMP_Round 60 (Round Corrugated Metal Pipe) Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 60.0" Wide + 30.0" Spacing = 90.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +285.00' Row Adjustment +5.00' Header x 2 = 315.00' Row Length +12.0" End Stone x 2 = 317.00' Base Length 6 Rows x 60.0" Wide + 30.0" Spacing x 5 + 12.0" Side Stone x 2 = 44.50' Base Width 6.0" Base + 60.0" Chamber Height + 6.0" Cover = 6.00' Field Height 6 Chambers x 391.8 cf +285.00' Row Adjustment x 19.59 sf x 6 Rows + 42.50' Header x 19.59 sf x 2 = 37,514.9 cf Chamber Storage 84,639.0 cf Field - 37,514.9 cf Chambers = 47,124.1 cf Stone x 40.0% Voids = 18,849.7 cf Stone Storage Chamber Storage + Stone Storage = 56,364.5 cf= 1.294 of Overall Storage Efficiency = 66.6% 6 Chambers 3,134.8 cy Field 1,745.3 cy Stone The Arsenal Project-Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 58 Pond SSI-2: Subsurface Infiltration System 2 Hydrograph ■Inflow — 44.69 cfs I — — - ■outflow 50_ / �I41o�vA�e65.2f6'a� ;Discarded 45�'/ 40� / /_$torage;�5M QI5 cfs I J_ t- -4 � 30�Z ,—I t I r I -1 t- 22.09 cfs 25� ° / � I I I I I I I I 21.26 cfs u. 20� / I I I I 15� — 5L­ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 59 Summary for Link POA-1: 30" Pipe Inflow Area = 11.703 ac, 92.70% Impervious, Inflow Depth = 0.57" for 100-Year Cornell event Inflow = 13.43 cfs @ 12.46 hrs, Volume= 0.559 of Primary = 13.43 cfs @ 12.46 hrs, Volume= 0.559 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-1: 30" Pipe Hydrographh /� _ _ _ _ _ _ - T ❑Inflow 15= ❑Primary 1a� n 1oO v A� e1=i 111 13.43 cfs 13 I— I I L I I L I —I I I- 12� � � 1 -1 fil t -T T T T 7 T 0 7 -4 � I � + LL � 6� L L — — 4� � 1� 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 60 Summary for Link POA-2: 15" Pipe Inflow Area = 1.324 ac, 83.32% Impervious, Inflow Depth > 7.93" for 100-Year Cornell event Inflow = 11.00 cfs @ 12.09 hrs, Volume= 0.875 of Primary = 11.00 cfs @ 12.09 hrs, Volume= 0.875 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-2: 15" Pipe Hydrograph / Inflow 12 ❑Primary 11� -I'rt i IA�re �a .3 11.00 cfs 9i-' ,- 8 a 7� U 3 6� 0 LL 5� 3� 1� .. ..�..�...�....,:...T........,,. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Proposed Type 111 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 61 Summary for Link POA-3: 18" Pipe and 24" Pipe Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth = 5.02" for 100-Year Cornell event Inflow = 21.26 cfs @ 12.24 hrs, Volume= 2.208 of Primary = 21.26 cfs @ 12.24 hrs, Volume= 2.208 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-3: 18" Pipe and 24" Pipe Hydrograph - I❑Inflow 23 — 21.26 cfS 0 Primary 2, �Inlow Are -s2 — — — 20 � 14 I -4 4- I 1 I- 14 � I � I 19 V —1 1— -- - — 16/ ,— 15. 13 I T — — 12� � IL 9V — — 8 7�% � I4 � I -44- I 1 - 14 I � � I 1 1� 6 4 - - - - - I I - I - -1 — —I - I_ 3 2" 1 o �..�..�..�..�..i...�... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Future Post-Redevelopment Hydrological Computations POA-3 18" Pipe a d 24" Pipe ASSI-2 [POA]-2 Subs rface Infi ation 15" Pipe System 2 HDPR-3B PR-3A PR-2 HD Parking Lot East Portion of Lot Sout Portion of Lot PR-1A North Portion of Lot PR-1 B 77 HVt Lot SSI-1 SSI-3 ubsurface Infiltration Subsurface Infiltration System 1 System 3 POA-1 30" Pipe SubCat Reach on Link Routing Diagram for The Arsenal Project-Future Proposed Prepared by RJO'Connell&Associates, Inc., Printed 6/14/2016 HydroCAD®10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 2 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentHDPR-3B: HD Parking Lot Runoff Area=66,885 sf 87.83% Impervious Runoff Depth>2.44" Tc=6.0 min CN=93 Runoff=4.17 cfs 0.313 of SubcatchmentPR-1A: North Portion of Runoff Area=393,607 sf 96.73% Impervious Runoff Depth>2.75" Tc=6.0 min CN=96 Runoff=26.48 cfs 2.069 of Subcatchment PR-1 B: HVMA Lot Runoff Area=155,841 sf 82.30% Impervious Runoff Depth>2.26" Tc=6.0 min CN=91 Runoff=9.11 cfs 0.673 of SubcatchmentPR-2: South Portion of Lot Runoff Area=57,681 sf 83.32% Impervious Runoff Depth>2.35" Tc=6.0 min CN=92 Runoff=3.49 cfs 0.259 of SubcatchmentPR-3A: East Portion of Lot Runoff Area=162,941 sf 96.59% Impervious Runoff Depth>2.85" Tc=6.0 min CN=97 Runoff=11.18 cfs 0.890 of Pond SSI-1: Subsurface Infiltration System Peak Elev=16.17' Storage=30,244 cf Inflow=29.97 cfs 2.328 of Discarded=5.73 cfs 2.326 of Primary=0.00 cfs 0.000 of Outflow=5.73 cfs 2.326 of Pond SSI-2: Subsurface Infiltration System Peak EIev=10.95' Storage=27,631 cf Inflow=15.34 cfs 1.203 of Discarded=0.58 cfs 0.706 of Primary=0.51 cfs 0.101 of Outflow=1.08 cfs 0.807 of Pond SSI-3: Subsurface Infiltration System 3 Peak EIev=13.79' Storage=16,289 cf Inflow=9.11 cfs 0.673 of Outflow=0.41 cfs 0.456 of Link POA-1: 30" Pipe Inflow=0.00 cfs 0.000 of Primary=0.00 cfs 0.000 of Link POA-2: 15" Pipe Primary=0.00 cfs 0.000 of Link POA-3: 18" Pipe and 24" Pipe Inflow=0.51 cfs 0.101 of Primary=0.51 cfs 0.101 of Total Runoff Area = 19.214 ac Runoff Volume = 4.203 of Average Runoff Depth = 2.63" 7.62% Pervious = 1.464 ac 92.38% Impervious = 17.749 ac The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 3 Summary for Subcatchment HDPR-313: HD Parking Lot Runoff = 4.17 cfs @ 12.09 hrs, Volume= 0.313 af, Depth> 2.44" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 8,139 61 >75% Grass cover, Good, HSG B 58,746 98 Paved parkinq, HSG B 66,885 93 Weighted Average 8,139 12.17% Pervious Area 58,746 87.83% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment HDPR-313: HD Parking Lot Hydrograph - ❑Runoff cfs 4 I—Ty IIfiZ4-ti� 4.17 r 12�Year Cornell Rainfoll�IgO` Area=6 ,8�5 f4=ff,Volume�L-0.31 ;-'� Runoff Depth>2.44" T =�.0 min 3 � N--93 LL 2 o ..�..�..�..�.. ....�...,:.. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 4 Summary for Subcatchment PR-1A: North Portion of Lot Runoff = 26.48 cfs @ 12.09 hrs, Volume= 2.069 af, Depth> 2.75" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 12,883 39 >75% Grass cover, Good, HSG A 174,583 98 Roofs, HSG A 206,141 98 Paved parkinq, HSG A 393,607 96 Weighted Average 12,883 3.27% Pervious Area 380,724 96.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1A: North Portion of Lot Hydrograph .�� I ❑Runoff 28-_�/ � 11 26.48 cfs 26� - 24�-/12�Yoar ICornoll Railnfoll�3.?O" 22�'/_ unoff � Area=3 3,�07 sff fi —unoffVdu20�I n of 18—/ Ru_6o"4pttlh>Z7 ! � LTFF " 12� 10� � I -1 T 4� 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 5 Summary for Subcatchment PR-1 B: HVMA Lot Runoff = 9.11 cfs @ 12.09 hrs, Volume= 0.673 af, Depth> 2.26" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 27,588 61 >75% Grass cover, Good, HSG B 18,625 98 Roofs, HSG B 109,628 98 Paved parkinq, HSG B 155,841 91 Weighted Average 27,588 17.70% Pervious Area 128,253 82.30% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1 B: HVMA Lot Hydrograph 10_/' ❑Runoff 9��T� 11�2 -h� 9.11 cfs $�r2�Yoar�Corrr-dll-Rainfoltz�3.2O" - I —I fi 7�Iu- no"rea=155lI ,841s#� T 7 T _T T_ I -1 unoff Vdlume=0.�67 a# 6--/ Rlu_n_1o"6ptlh>_Z.2 " T T T T I T T T U - LL 2� 1� 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 6 Summary for Subcatchment PR-2: South Portion of Lot Runoff = 3.49 cfs @ 12.09 hrs, Volume= 0.259 af, Depth> 2.35" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 9,621 61 >75% Grass cover, Good, HSG B 40,578 98 Roofs, HSG B 7,482 98 Paved parkinq, HSG B 57,681 92 Weighted Average 9,621 16.68% Pervious Area 48,060 83.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-2: South Portion of Lot Hydrograph �I - ❑Runoff Type III 24-hi- I 13.49 cfs 3�1-2 1Y far'Cdr ll-Rai-nfoll=�3.p" �unpff Area-57,681 f LL unloff VolumeL0.125: of Runloff Depth>2.35" 2/mac,c- .0 min CN-921 .2 IIIIIIIII ' ( IIIII I � - - II ' Illll ' III o ,:...,. ../... .. ..�.../....�:...�:.........:.... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 7 Summary for Subcatchment PR-3A: East Portion of Lot Runoff = 11.18 cfs @ 12.09 hrs, Volume= 0.890 af, Depth> 2.85" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Cornell Rainfall=3.20" Area (sf) CN Description 5,559 61 >75% Grass cover, Good, HSG B 67,368 98 Roofs, HSG B 90,014 98 Paved parkinq, HSG B 162,941 97 Weighted Average 5,559 3.41% Pervious Area 157,382 96.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-3A: East Portion of Lot Hydrograph 12� 11 11.18 CfS ■Runoff T�� 11�24-h fi - 10� 2�YoarICorndll Railnfoll�3.?O" 9� u tIoff-ArlIes=162, 41ll stL — urYoff�dh�me-00 of N $ -luno"Opfh>2.8 ' --1 4- - 1 3 6� ��N 971 � I -I T rt t- I -I 3 o- :... :... '... .. .. ..�..�..�...r:...�:...�....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type /// 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 8 Summary for Pond SSI-1: Subsurface Infiltration System 1 Inflow Area = 10.360 ac, 95.01% Impervious, Inflow Depth > 2.70" for 2-Year Cornell event Inflow = 29.97 cfs @ 12.09 hrs, Volume= 2.328 of Outflow = 5.73 cfs @ 12.53 hrs, Volume= 2.326 af, Atten= 81%, Lag= 26.4 min Discarded = 5.73 cfs @ 12.53 hrs, Volume= 2.326 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 16.17' @ 12.53 hrs Surf.Area= 14,652 sf Storage= 30,244 cf Plug-Flow detention time= 38.6 min calculated for 2.321 of(100% of inflow) Center-of-Mass det. time= 38.0 min ( 814.2 - 776.2 ) Volume Invert Avail.Storage Storage Description #1A 12.00' 40,931 cf 66.00'W x 222.00'L x 13.00'H Field A 190,476 cf Overall - 88,150 cf Embedded = 102,326 cf x 40.0% Voids #2A 14.50' 88,150 cf CMP_Round 120 x 5 Inside #1 Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.00'L Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 62.00' Header x 78.43 sf x 2 = 9,724.7 cf Inside 129,080 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 22.50' 24.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 22.50' /22.45' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf #2 Discarded 12.00' 8.270 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 8.00' Discarded OutFlow Max=5.73 cfs @ 12.53 hrs HW=16.17' (Free Discharge) L2=Exfiltration ( Controls 5.73 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.00' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 9 Pond SSI-1: Subsurface Infiltration System 1 - Chamber Wizard Field A Chamber Model = CMP_Round 120 (Round Corrugated Metal Pipe) Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.001 Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 120.0" Wide + 36.0" Spacing = 156.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +180.00' Row Adjustment +10.00' Header x 2 = 220.00' Row Length +12.0" End Stone x 2 = 222.00' Base Length 5 Rows x 120.0" Wide + 36.0" Spacing x 4 + 24.0" Side Stone x 2 = 66.00' Base Width 30.0" Base + 120.0" Chamber Height + 6.0" Cover = 13.00' Field Height 5 Chambers x 1,568.5 cf +180.00' Row Adjustment x 78.43 sf x 5 Rows + 62.00' Header x 78.43 sf x 2 = 88,149.7 cf Chamber Storage 190,476.0 cf Field - 88,149.7 cf Chambers = 102,326.3 cf Stone x 40.0% Voids = 40,930.5 cf Stone Storage Chamber Storage + Stone Storage = 129,080.2 cf= 2.963 of Overall Storage Efficiency = 67.8% 5 Chambers 7,054.7 cy Field 3,789.9 cy Stone The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 10 Pond SSI-1: Subsurface Infiltration System 1 Hydrograph ❑ Inflow 29.97 cfs outflow ' 146N-A ie��/1�60 a ❑Discarded / ' „v f1 v.vVV� El Primary 32 26 22% � ICI LIB LIB � 181 �I L I I _L IA LIB � I � �I - 14� / /'I I I I Z 1� Z ::11 1 L l Z 12/ BIZ 1 1 11 -7 1 71- ZI _ 10 / 5.73 cfs $: T 4- 0.00 cfs // 0 „/,/f � //JiP f A f(�f f(�� (�J�eAi--------���eR 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type /// 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 11 Summary for Pond SSI-2: Subsurface Infiltration System 2 Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth > 2.74" for 2-Year Cornell event Inflow = 15.34 cfs @ 12.09 hrs, Volume= 1.203 of Outflow = 1.08 cfs @ 13.41 hrs, Volume= 0.807 af, Atten= 93%, Lag= 79.2 min Discarded = 0.58 cfs @ 13.41 hrs, Volume= 0.706 of Primary = 0.51 cfs @ 13.41 hrs, Volume= 0.101 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 10.95' @ 13.41 hrs Surf.Area= 14,107 sf Storage= 27,631 cf Plug-Flow detention time= 261.8 min calculated for 0.805 of(67% of inflow) Center-of-Mass det. time= 166.5 min ( 939.0 - 772.5 ) Volume Invert Avail.Storage Storage Description #1A 8.00' 18,850 cf 44.50'W x 317.00'L x 6.00'H Field A 84,639 cf Overall - 37,515 cf Embedded = 47,124 cf x 40.0% Voids #2A 8.50' 37,515 cf CMP_Round 60 x 6 Inside #1 Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 42.50' Header x 19.59 sf x 2 = 1,665.2 cf Inside 56,365 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #2 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/ Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #3 Discarded 8.00' 1.020 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 4.00' Discarded OutFlow Max=0.58 cfs @ 13.41 hrs HW=10.95' (Free Discharge) L3=Exfiltration ( Controls 0.58 cfs) Primary OutFlow Max=0.50 cfs @ 13.41 hrs HW=10.95' (Free Discharge) �__1=Culvert (Barrel Controls 0.25 cfs @ 1.95 fps) 2=Culvert (Barrel Controls 0.25 cfs @ 1.95 fps) The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 12 Pond SSI-2: Subsurface Infiltration System 2 - Chamber Wizard Field A Chamber Model = CMP_Round 60 (Round Corrugated Metal Pipe) Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 60.0" Wide + 30.0" Spacing = 90.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +285.00' Row Adjustment +5.00' Header x 2 = 315.00' Row Length +12.0" End Stone x 2 = 317.00' Base Length 6 Rows x 60.0" Wide + 30.0" Spacing x 5 + 12.0" Side Stone x 2 = 44.50' Base Width 6.0" Base + 60.0" Chamber Height + 6.0" Cover = 6.00' Field Height 6 Chambers x 391.8 cf +285.00' Row Adjustment x 19.59 sf x 6 Rows + 42.50' Header x 19.59 sf x 2 = 37,514.9 cf Chamber Storage 84,639.0 cf Field - 37,514.9 cf Chambers = 47,124.1 cf Stone x 40.0% Voids = 18,849.7 cf Stone Storage Chamber Storage + Stone Storage = 56,364.5 cf= 1.294 of Overall Storage Efficiency = 66.6% 6 Chambers 3,134.8 cy Field 1,745.3 cy Stone The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 13 Pond SSI-2: Subsurface Infiltration System 2 Hydrograph I T I- J I r- I El Inflow N `_, /��.� c �+1�5. El 34 outflow 17= / A H-FO' ii AI eii i5 �F7'Q ❑Primary 15 / Teal le v 3r0. 'rt - - - - - - - 14�;__/ / r$tOr49e:217634 IC#t rt l I _r I _1 fi I r_ l 13� / — 12: /-I T I-I T I -1 T _T 7 I I T 17 T -1 E-I ,9 Ii - -I - - - - - 6-V -IT 1-1 771 � � - TI7 TIC r 4 / �I T 7 1.08 cfs 3_ 2: 1 0.51 sl�Em_ o` .. ...�.. ,,.. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type /// 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 14 Summary for Pond SSI-3: Subsurface Infiltration System 3 Inflow Area = 3.578 ac, 82.30% Impervious, Inflow Depth > 2.26" for 2-Year Cornell event Inflow = 9.11 cfs @ 12.09 hrs, Volume= 0.673 of Outflow = 0.41 cfs @ 14.99 hrs, Volume= 0.456 af, Atten= 95%, Lag= 174.0 min Discarded = 0.41 cfs @ 14.99 hrs, Volume= 0.456 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 13.79' @ 14.99 hrs Surf.Area= 10,266 sf Storage= 16,289 cf Plug-Flow detention time= 299.3 min calculated for 0.456 of(68% of inflow) Center-of-Mass det. time= 203.9 min ( 1,005.9 - 802.0 ) Volume Invert Avail.Storage Storaqe Description #1A 11.00, 21,584 cf 87.00'W x 118.00'L x 10.00'H Field A 102,660 cf Overall - 48,699 cf Embedded = 53,961 cf x 40.0% Voids #2A 12.00' 48,699 cf CMP_Round 96 x 8 Inside #1 Effective Size= 96.0"W x 96.0"H => 50.20 sf x 20.001 = 1,004.1 cf Overall Size= 96.0"W x 96.0"H x 20.001 Row Length Adjustment= +80.00' x 50.20 sf x 8 rows 85.00' Header x 50.20 sf x 2 = 8,534.8 cf Inside 70,283 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Discarded 11.00' 1.020 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 7.00' Discarded OutFlow Max=0.41 cfs @ 14.99 hrs HW=13.79' (Free Discharge) L1=Exfiltration ( Controls 0.41 cfs) The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 15 Pond SSI-3: Subsurface Infiltration System 3 - Chamber Wizard Field A Chamber Model = CMP_Round 96 (Round Corrugated Metal Pipe) Effective Size= 96.0"W x 96.0"H => 50.20 sf x 20.001 = 1,004.1 cf Overall Size= 96.0"W x 96.0"H x 20.001 Row Length Adjustment= +80.00' x 50.20 sf x 8 rows 96.0" Wide + 36.0" Spacing = 132.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +80.00' Row Adjustment +8.00' Header x 2 = 116.00' Row Length +12.0" End Stone x 2 = 118.00' Base Length 8 Rows x 96.0" Wide + 36.0" Spacing x 7 + 12.0" Side Stone x 2 = 87.00' Base Width 12.0" Base + 96.0" Chamber Height + 12.0" Cover = 10.00' Field Height 8 Chambers x 1,004.1 cf +80.00' Row Adjustment x 50.20 sf x 8 Rows + 85.00' Header x 50.20 sf x 2 = 48,698.8 cf Chamber Storage 102,660.0 cf Field -48,698.8 cf Chambers = 53,961.1 cf Stone x 40.0% Voids = 21,584.5 cf Stone Storage Chamber Storage + Stone Storage = 70,283.3 cf= 1.613 of Overall Storage Efficiency = 68.5% 8 Chambers 3,802.2 cy Field 1,998.6 cy Stone I I The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 16 Pond SSI-3: Subsurface Infiltration System 3 Hydrograph / ❑Inflow 10.;:/ _ 9.11 cfs 0 Discarded 9 �I'n�lovv_ 'Area=1578 ad 8� ��ak_Elew�13.�9� l u l l — 3 5� o _ " 4�/ I I I I I I I I I I I 3� I I L -1 L- 1 -1 L I 1� 0.41 cfs 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 17 Summary for Link POA-1: 30" Pipe Inflow Area = 10.360 ac, 95.01% Impervious, Inflow Depth = 0.00" for 2-Year Cornell event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-1: 30" Pipe Hydrograph �I i C Inflow 1 I fl I�fllo�v 4r66= 0.3601a� ❑Primary Illllllill � i II ' Illlll � � ' 3 0 LL 0.00 cfs 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 18 Summary for Link POA-2: 15" Pipe Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-2: 15" Pipe Hydrograph ❑Primary N 3 0 LL 0.00 cfs 0 6W-OV144. 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 2-Year Cornell Rainfall=3.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 19 Summary for Link POA-3: 18" Pipe and 24" Pipe Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth = 0.23" for 2-Year Cornell event Inflow = 0.51 cfs @ 13.41 hrs, Volume= 0.101 of Primary = 0.51 cfs @ 13.41 hrs, Volume= 0.101 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-3: 18" Pipe and 24" Pipe Hydrograph � I4 � I � I � � � 4- 1 ❑Inflow 005 Inflow Area 5.276 0.51 cfs - ❑Primary 0.45-i'/ 0.35�-/ 3 i° 0.25�1/ 0.15-�/ — 0.05� 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 20 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentHDPR-3B: HD Parking Lot Runoff Area=66,885 sf 87.83% Impervious Runoff Depth>4.10" Tc=6.0 min CN=93 Runoff=6.79 cfs 0.524 of SubcatchmentPR-1A: North Portion of Runoff Area=393,607 sf 96.73% Impervious Runoff Depth>4.43" Tc=6.0 min CN=96 Runoff=41.59 cfs 3.336 of Subcatchment PR-1 B: HVMA Lot Runoff Area=155,841 sf 82.30% Impervious Runoff Depth>3.88" Tc=6.0 min CN=91 Runoff=15.27 cfs 1.157 of SubcatchmentPR-2: South Portion of Lot Runoff Area=57,681 sf 83.32% Impervious Runoff Depth>3.99" Tc=6.0 min CN=92 Runoff=5.76 cfs 0.440 of SubcatchmentPR-3A: East Portion of Lot Runoff Area=162,941 sf 96.59% Impervious Runoff Depth>4.54" Tc=6.0 min CN=97 Runoff=17.38 cfs 1.417 of Pond SSI-1: Subsurface Infiltration System Peak Elev=18.32' Storage=55,609 cf Inflow=47.34 cfs 3.776 of Discarded=7.24 cfs 3.774 of Primary=0.00 cfs 0.000 of Outflow=7.24 cfs 3.774 of Pond SSI-2: Subsurface Infiltration System Peak Elev=11.79' Storage=37,088 cf Inflow=24.17 cfs 1.941 of Discarded=0.65 cfs 0.789 of Primary=6.69 cfs 0.681 of Outflow=7.34 cfs 1.470 of Pond SSI-3: Subsurface Infiltration System Peak Elev=15.57' Storage=31,392 cf Inflow=15.27 cfs 1.157 of Outflow=0.52 cfs 0.604 of Link POA-1: 30" Pipe Inflow=0.00 cfs 0.000 of Primary=0.00 cfs 0.000 of Link POA-2: 15" Pipe Primary=0.00 cfs 0.000 of Link POA-3: 18" Pipe and 24" Pipe Inflow=6.69 cfs 0.681 of Primary=6.69 cfs 0.681 of Total Runoff Area = 19.214 ac Runoff Volume = 6.875 of Average Runoff Depth = 4.29" 7.62% Pervious = 1.464 ac 92.38% Impervious = 17.749 ac The Arsenal Project-Future Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 21 Summary for Subcatchment HDPR-3B: HD Parking Lot Runoff = 6.79 cfs @ 12.09 hrs, Volume= 0.524 af, Depth> 4.10" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 8,139 61 >75% Grass cover, Good, HSG B 58,746 98 Paved parkinq, HSG B 66,885 93 Weighted Average 8,139 12.17% Pervious Area 58,746 87.83% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment HDPR-3B: HD Parking Lot Hydrograph ❑Runoff 6.79 cfs 7_ Type III 24-hr 6_�,/1-1I9'fpar CornplTa1nfOI".W' Runoff Area=66,88T"24 s 5��­2unn ff'to�urr�e=0. af4 Runoff Depth)>4.I101' 3 4� i C =63 0 LL 1 o ../..1..�..�.. ....�.. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 22 Summary for Subcatchment PR-1A: North Portion of Lot Runoff = 41.59 cfs @ 12.09 hrs, Volume= 3.336 af, Depth> 4.43" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 12,883 39 >75% Grass cover, Good, HSG A 174,583 98 Roofs, HSG A 206,141 98 Paved parkinq, HSG A 393,607 96 Weighted Average 12,883 3.27% Pervious Area 380,724 96.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1A: North Portion of Lot Hydrograph ■ 46� — Runoff 44- — 41.59 cfs 40-—TJ_D1 IU�2�--h� 38 t�1P-Yea-lr-C hei�R f "01' — I __1 36-- — f—A — — — — — — — 32 I_Znoff Vdlin 3 7� 30_ �Iu6o"Opth>4 ., -1 4- 14 1 � - 28�I w 26_�_/ — — — — — — — — — 24 .O�mir>L rt f— fi - - fi — - - - 0 22' LL18- 1 1 - T I __� J_ 1-1 1 __1 16 - — 18 1 -7 T I CI _ EIS T _T —I - 6- — 4 ' 1 4 14 - 2 o` :... :... '... .. .. ..�..�..�...�:...�:...�....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 23 Summary for Subcatchment PR-1 B: HVMA Lot Runoff = 15.27 cfs @ 12.09 hrs, Volume= 1.157 af, Depth> 3.88" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 27,588 61 >75% Grass cover, Good, HSG B 18,625 98 Roofs, HSG B 109,628 98 Paved parkinq, HSG B 155,841 91 Weighted Average 27,588 17.70% Pervious Area 128,253 82.30% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1 B: HVMA Lot Hydrograph 17=� 7 T T _T ■Runoff 16=/ 11 15.27 cfs 15 T�� 11�24-h� — 14� 1 p-_Yea�Corfielt R$in fatl�7-"01' 13✓ unloIfflI Area=1-55, 1II sf - 12u>�off lume=1 - 11_ 10�_/ _1�u_nTo"Optlh>3.8$w 7 7 9-1 T�c .O,miln I - o 8✓ 7 k 1 14 �- I —I - 6� _ _ _ _ _ _ _ _ _ _ _ _ 5� -J L 1 -1 LI � I __1 I I I __L L1 -1 4'/ 2� 1� 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 24 Summary for Subcatchment PR-2: South Portion of Lot Runoff = 5.76 cfs @ 12.09 hrs, Volume= 0.440 af, Depth> 3.99" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 9,621 61 >75% Grass cover, Good, HSG B 40,578 98 Roofs, HSG B 7,482 98 Paved parkinq, HSG B 57,681 92 Weighted Average 9,621 16.68% Pervious Area 48,060 83.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-2: South Portion of Lot Hydrograph �� I I _ _ ■Runoff 6�I Type III24�hr I I I 5.76 cfs S-,-/j-lQ-YiearCompll-fZalnf�l"•9V' I I t I I _ Runoff Area=57,681 sf Runoff'Volume=b.401af l l Rlunoff Depthl>3.I991' U Tc=6.0 min 3 � CN-92- I _ - LL 2�Z 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 25 Summary for Subcatchment PR-3A: East Portion of Lot Runoff = 17.38 cfs @ 12.09 hrs, Volume= 1.417 af, Depth> 4.54" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Cornell Rainfall=4.90" Area (sf) CN Description 5,559 61 >75% Grass cover, Good, HSG B 67,368 98 Roofs, HSG B 90,014 98 Paved parkinq, HSG B 162,941 97 Weighted Average 5,559 3.41% Pervious Area 157,382 96.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-3A: East Portion of Lot Hydrograph � I 1s� 11 � 17.38 cfs � 17- T�� 11�24--h� - - - 116 5 �P-Ye�l_h�R f� 01' 1 1 1 14� unoff�►rea- , 1 $ 13�� unof�dlulne-1.41 7 12 i-] uUrt6"Opth>4-5 " 1 -1 4- H _ I - U 11 _ Amin - 0 9 / 1.�97 LL 8 1-1 61 5=,_ I �- — I—I — — — — I — — — — I 1 — — —I - 31_ I 1 + � I I � + 1_I 1 I � 1= 0" ,....,:...,-....�:..�..�..�..�:.. ...�...,:...,....,.... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type /// 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 26 Summary for Pond SSI-1: Subsurface Infiltration System 1 Inflow Area = 10.360 ac, 95.01% Impervious, Inflow Depth > 4.37" for 10-Year Cornell event Inflow = 47.34 cfs @ 12.09 hrs, Volume= 3.776 of Outflow = 7.24 cfs @ 12.58 hrs, Volume= 3.774 af, Atten= 85%, Lag= 29.4 min Discarded = 7.24 cfs @ 12.58 hrs, Volume= 3.774 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 18.32' @ 12.58 hrs Surf.Area= 14,652 sf Storage= 55,609 cf Plug-Flow detention time= 61.7 min calculated for 3.766 of(100% of inflow) Center-of-Mass det. time= 61.1 min ( 825.9 - 764.8 ) Volume Invert Avail.Storage Storage Description #1A 12.00' 40,931 cf 66.00'W x 222.00'L x 13.00'H Field A 190,476 cf Overall - 88,150 cf Embedded = 102,326 cf x 40.0% Voids #2A 14.50' 88,150 cf CMP_Round 120 x 5 Inside #1 Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.00'L Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 62.00' Header x 78.43 sf x 2 = 9,724.7 cf Inside 129,080 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 22.50' 24.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 22.50' /22.45' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf #2 Discarded 12.00' 8.270 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 8.00' Discarded OutFlow Max=7.24 cfs @ 12.58 hrs HW=18.32' (Free Discharge) L2=Exfiltration ( Controls 7.24 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.00' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) The Arsenal Project-Future Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 27 Pond SSI-1: Subsurface Infiltration System 1 - Chamber Wizard Field A Chamber Model = CMP_Round 120 (Round Corrugated Metal Pipe) Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.001 Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 120.0" Wide + 36.0" Spacing = 156.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +180.00' Row Adjustment +10.00' Header x 2 = 220.00' Row Length +12.0" End Stone x 2 = 222.00' Base Length 5 Rows x 120.0" Wide + 36.0" Spacing x 4 + 24.0" Side Stone x 2 = 66.00' Base Width 30.0" Base + 120.0" Chamber Height + 6.0" Cover = 13.00' Field Height 5 Chambers x 1,568.5 cf +180.00' Row Adjustment x 78.43 sf x 5 Rows + 62.00' Header x 78.43 sf x 2 = 88,149.7 cf Chamber Storage 190,476.0 cf Field - 88,149.7 cf Chambers = 102,326.3 cf Stone x 40.0% Voids = 40,930.5 cf Stone Storage Chamber Storage + Stone Storage = 129,080.2 cf= 2.963 of Overall Storage Efficiency = 67.8% 5 Chambers 7,054.7 cy Field 3,789.9 cy Stone The Arsenal Project-Future Proposed Type 111 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 28 Pond SSI-1: Subsurface Infiltration System 1 Hydrograph 11 1I_ L El �7.34 cfs o Ou�tflloow Inflow Area=10.360 aI —I o Discarded 50 /i Peak Elev=18.32'I -T 45 i �St ra a=55,609 f I I I I I I I I I 40- i/ Q 9 - 35�/ L -1 L 3°-' ,- I LL25 rt films 20- I I I I I 15� , 7.24 cfs 0.00 cfs 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type /// 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 29 Summary for Pond SSI-2: Subsurface Infiltration System 2 Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth > 4.41" for 10-Year Cornell event Inflow = 24.17 cfs @ 12.09 hrs, Volume= 1.941 of Outflow = 7.34 cfs @ 12.40 hrs, Volume= 1.470 af, Atten= 70%, Lag= 19.1 min Discarded = 0.65 cfs @ 12.41 hrs, Volume= 0.789 of Primary = 6.69 cfs @ 12.40 hrs, Volume= 0.681 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 11.79' @ 12.41 hrs Surf.Area= 14,107 sf Storage= 37,088 cf Plug-Flow detention time= 180.8 min calculated for 1.467 of(76% of inflow) Center-of-Mass det. time= 97.7 min ( 859.6 - 761.9 ) Volume Invert Avail.Storage Storage Description #1A 8.00' 18,850 cf 44.50'W x 317.00'L x 6.00'H Field A 84,639 cf Overall - 37,515 cf Embedded = 47,124 cf x 40.0% Voids #2A 8.50' 37,515 cf CMP_Round 60 x 6 Inside #1 Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 42.50' Header x 19.59 sf x 2 = 1,665.2 cf Inside 56,365 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #2 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/ Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #3 Discarded 8.00' 1.020 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 4.00' Discarded OutFlow Max=0.65 cfs @ 12.41 hrs HW=11.79' (Free Discharge) L3=Exfiltration ( Controls 0.65 cfs) Primary OutFlow Max=6.68 cfs @ 12.40 hrs HW=11.79' (Free Discharge) �__1=Culvert (Barrel Controls 3.34 cfs @ 3.40 fps) 2=Culvert (Barrel Controls 3.34 cfs @ 3.40 fps) The Arsenal Project-Future Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 30 Pond SSI-2: Subsurface Infiltration System 2 - Chamber Wizard Field A Chamber Model = CMP_Round 60 (Round Corrugated Metal Pipe) Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 60.0" Wide + 30.0" Spacing = 90.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +285.00' Row Adjustment +5.00' Header x 2 = 315.00' Row Length +12.0" End Stone x 2 = 317.00' Base Length 6 Rows x 60.0" Wide + 30.0" Spacing x 5 + 12.0" Side Stone x 2 = 44.50' Base Width 6.0" Base + 60.0" Chamber Height + 6.0" Cover = 6.00' Field Height 6 Chambers x 391.8 cf +285.00' Row Adjustment x 19.59 sf x 6 Rows + 42.50' Header x 19.59 sf x 2 = 37,514.9 cf Chamber Storage 84,639.0 cf Field - 37,514.9 cf Chambers = 47,124.1 cf Stone x 40.0% Voids = 18,849.7 cf Stone Storage Chamber Storage + Stone Storage = 56,364.5 cf= 1.294 of Overall Storage Efficiency = 66.6% 6 Chambers 3,134.8 cy Field 1,745.3 cy Stone The Arsenal Project-Future Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 31 Pond SSI-2: Subsurface Infiltration System 2 Hydrograph �I1 4- I -4 �— I 4 11 4- I� 4 -4 24.17 cfs — i outflow '1�0ff1��5�� Discarded 26� / �' 24�Z / /' Na"I eve--" ."'-f _+ 1 J_ I _f �_ 22� / L$t_OrOAe�37J8L Of _L 1 1 1 1� L _L L- 20�/ / LL 12 / �I T T 1 -17.34cfs T I� FI 186.69 cfs 4 __4 4 4 — 4— / 2 0 �...(...�:...�....,. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type /// 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 32 Summary for Pond SSI-3: Subsurface Infiltration System 3 Inflow Area = 3.578 ac, 82.30% Impervious, Inflow Depth > 3.88" for 10-Year Cornell event Inflow = 15.27 cfs @ 12.09 hrs, Volume= 1.157 of Outflow = 0.52 cfs @ 15.70 hrs, Volume= 0.604 af, Atten= 97%, Lag= 216.6 min Discarded = 0.52 cfs @ 15.70 hrs, Volume= 0.604 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 15.57' @ 15.70 hrs Surf.Area= 10,266 sf Storage= 31,392 cf Plug-Flow detention time= 310.7 min calculated for 0.603 of(52% of inflow) Center-of-Mass det. time= 200.5 min ( 987.6 - 787.0 ) Volume Invert Avail.Storage Storaqe Description #1A 11.00, 21,584 cf 87.00'W x 118.00'L x 10.00'H Field A 102,660 cf Overall - 48,699 cf Embedded = 53,961 cf x 40.0% Voids #2A 12.00' 48,699 cf CMP_Round 96 x 8 Inside #1 Effective Size= 96.0"W x 96.0"H => 50.20 sf x 20.001 = 1,004.1 cf Overall Size= 96.0"W x 96.0"H x 20.001 Row Length Adjustment= +80.00' x 50.20 sf x 8 rows 85.00' Header x 50.20 sf x 2 = 8,534.8 cf Inside 70,283 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Discarded 11.00' 1.020 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 7.00' Discarded OutFlow Max=0.52 cfs @ 15.70 hrs HW=15.57' (Free Discharge) L1=Exfiltration ( Controls 0.52 cfs) The Arsenal Project-Future Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 33 Pond SSI-3: Subsurface Infiltration System 3 - Chamber Wizard Field A Chamber Model = CMP_Round 96 (Round Corrugated Metal Pipe) Effective Size= 96.0"W x 96.0"H => 50.20 sf x 20.001 = 1,004.1 cf Overall Size= 96.0"W x 96.0"H x 20.001 Row Length Adjustment= +80.00' x 50.20 sf x 8 rows 96.0" Wide + 36.0" Spacing = 132.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +80.00' Row Adjustment +8.00' Header x 2 = 116.00' Row Length +12.0" End Stone x 2 = 118.00' Base Length 8 Rows x 96.0" Wide + 36.0" Spacing x 7 + 12.0" Side Stone x 2 = 87.00' Base Width 12.0" Base + 96.0" Chamber Height + 12.0" Cover = 10.00' Field Height 8 Chambers x 1,004.1 cf +80.00' Row Adjustment x 50.20 sf x 8 Rows + 85.00' Header x 50.20 sf x 2 = 48,698.8 cf Chamber Storage 102,660.0 cf Field -48,698.8 cf Chambers = 53,961.1 cf Stone x 40.0% Voids = 21,584.5 cf Stone Storage Chamber Storage + Stone Storage = 70,283.3 cf= 1.613 of Overall Storage Efficiency = 68.5% 8 Chambers 3,802.2 cy Field 1,998.6 cy Stone I I The Arsenal Project-Future Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 34 Pond SSI-3: Subsurface Infiltration System 3 Hydrograph � I _J F ❑Inflow 17= 15.27 cfs I 0 Discarded 16 �11,, o i IA�ea�----3 57� at - — 15� i 14 eakle�v157 ,2 -$t6ri�e--�30k 6# l l l a 107 0 8 /T_ I -1 FI 7 FI _T T_ I -1 T 5?/ 3i'/ 2 0.52 cfs 1-= 0 (.... ... :... ... ... ...�...�...�...�........�...�..., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 35 Summary for Link POA-1: 30" Pipe Inflow Area = 10.360 ac, 95.01% Impervious, Inflow Depth = 0.00" for 10-Year Cornell event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-1: 30" Pipe Hydrograph �I i C Inflow 1 I I�fllo�v 4r66='�0.3601a� ❑Primary Illllllill � i II ' Illlll � � ' 3 0 LL 0.00 cfs 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 36 Summary for Link POA-2: 15" Pipe Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-2: 15" Pipe Hydrograph 1 / I❑Primary N 3 0 LL 0.00 cfs 0 6W-OV144. 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 10-Year Cornell Rainfall=4.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 37 Summary for Link POA-3: 18" Pipe and 24" Pipe Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth = 1.55" for 10-Year Cornell event Inflow = 6.69 cfs @ 12.40 hrs, Volume= 0.681 of Primary = 6.69 cfs @ 12.40 hrs, Volume= 0.681 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-3: 18" Pipe and 24" Pipe Hydrograph �I Inflow 6 ❑Primary .69 cfs l F_ 5 � I __4 I - 4 l l l l l l l l l I 3 � — 0 1� - I o ..�../...�.. ....�....,. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 38 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentHDPR-3B: HD Parking Lot Runoff Area=66,885 sf 87.83% Impervious Runoff Depth>5.38" Tc=6.0 min CN=93 Runoff=8.77 cfs 0.688 of SubcatchmentPR-1A: North Portion of Runoff Area=393,607 sf 96.73% Impervious Runoff Depth>5.72" Tc=6.0 min CN=96 Runoff=53.04 cfs 4.309 of Subcatchment PR-1 B: HVMA Lot Runoff Area=155,841 sf 82.30% Impervious Runoff Depth>5.15" Tc=6.0 min CN=91 Runoff=19.93 cfs 1.535 of SubcatchmentPR-2: South Portion of Lot Runoff Area=57,681 sf 83.32% Impervious Runoff Depth>5.26" Tc=6.0 min CN=92 Runoff=7.47 cfs 0.581 of SubcatchmentPR-3A: East Portion of Lot Runoff Area=162,941 sf 96.59% Impervious Runoff Depth>5.84" Tc=6.0 min CN=97 Runoff=22.09 cfs 1.820 of Pond SSI-1: Subsurface Infiltration System Peak Elev=19.99' Storage=76,525 cf Inflow=60.51 cfs 4.890 of Discarded=8.41 cfs 4.887 of Primary=0.00 cfs 0.000 of Outflow=8.41 cfs 4.887 of Pond SSI-2: Subsurface Infiltration System Peak Elev=12.37' Storage=43,368 cf Inflow=30.86 cfs 2.508 of Discarded=0.70 cfs 0.838 of Primary=12.74 cfs 1.158 of Outflow=13.44 cfs 1.996 of Pond SSI-3: Subsurface Infiltration System Peak Elev=16.97' Storage=43,556 cf Inflow=19.93 cfs 1.535 of Outflow=0.60 cfs 0.712 of Link POA-1: 30" Pipe Inflow=0.00 cfs 0.000 of Primary=0.00 cfs 0.000 of Link POA-2: 15" Pipe Primary=0.00 cfs 0.000 of Link POA-3: 18" Pipe and 24" Pipe Inflow=12.74 cfs 1.158 of Primary=12.74 cfs 1.158 of Total Runoff Area = 19.214 ac Runoff Volume = 8.934 of Average Runoff Depth = 5.58" 7.62% Pervious = 1.464 ac 92.38% Impervious = 17.749 ac The Arsenal Project-Future Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 39 Summary for Subcatchment HDPR-313: HD Parking Lot Runoff = 8.77 cfs @ 12.09 hrs, Volume= 0.688 af, Depth> 5.38" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 8,139 61 >75% Grass cover, Good, HSG B 58,746 98 Paved parkinq, HSG B 66,885 93 Weighted Average 8,139 12.17% Pervious Area 58,746 87.83% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment HDPR-313: HD Parking Lot Hydrograph - ❑Runoff 9_�'Z l � 8.77 cfs I T pe III 24 hr 8-�-/1 2�-Ypar Cornell II2aiInfOII=16.2p" -Runoff-Area=6"8�f Runoff Volume=b.6881af 6-:-/'l Runoff Pepthh5.1381' LL 4� 3� 2-1 - 1-_ 0 (:...�..�..�../..../..../.. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 40 Summary for Subcatchment PR-1A: North Portion of Lot Runoff = 53.04 cfs @ 12.09 hrs, Volume= 4.309 af, Depth> 5.72" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 12,883 39 >75% Grass cover, Good, HSG A 174,583 98 Roofs, HSG A 206,141 98 Paved parkinq, HSG A 393,607 96 Weighted Average 12,883 3.27% Pervious Area 380,724 96.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1A: North Portion of Lot Hydrograph _ _ O Runoff 55�'/ 53.04 cfs -TYp� I1-i-2"r - 50L I_25�ea�Clornell Rainfa11�6�201 4 1 - 45�_ unoff ArIea=393 60711 sff� 40� �unoff�Vdlu�ne=4.309 of 35-�-/1 Rluno"4pth>_$_.7 " 3 30=�� - .0—min - c 25 - 20=-'/ 10� o- :... :... '... ... .. ..�..�..�...r:...�:...�....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 41 Summary for Subcatchment PR-1 B: HVMA Lot Runoff = 19.93 cfs @ 12.09 hrs, Volume= 1.535 af, Depth> 5.15" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 27,588 61 >75% Grass cover, Good, HSG B 18,625 98 Roofs, HSG B 109,628 98 Paved parkinq, HSG B 155,841 91 Weighted Average 27,588 17.70% Pervious Area 128,253 82.30% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1 B: HVMA Lot Hydrograph 22=�� - � �_ — I �_ — ❑Runoff 21�—��/ � L I 1— 19.93cfs 20 � 1 � 1 1-1 _L L - � — ��241r� — — — — 18='l-25--yea�-CI hel�R faU�6�2oi' - 17 , unoff�►rea=1 -_ 15- unoff-VVMHne=1.535 — - - 13 In 12 _ .U-m l n - 311�I— 7 1 4 CIA � 1oNL=91— — — — — — -LL — - 9- 8 �— - 6�1— I � � � ICI � � � - 3� — 1� 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 42 Summary for Subcatchment PR-2: South Portion of Lot Runoff = 7.47 cfs @ 12.09 hrs, Volume= 0.581 af, Depth> 5.26" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 9,621 61 >75% Grass cover, Good, HSG B 40,578 98 Roofs, HSG B 7,482 98 Paved parkinq, HSG B 57,681 92 Weighted Average 9,621 16.68% Pervious Area 48,060 83.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-2: South Portion of Lot Hydrograph 8� ■Runoff 7.47 cfs - -Type 11V24-hrl 7� 2g-Year Cornell Rainfall=6.20" 6-,/ -RunQff-Area=57,68"f Runbff Volume=b.518l laf 5� Runoff Depth>5.261' Tc=6.0 min 4� CN=J2 rt l I � fil � I rt l I � .2 2- 1� 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 43 Summary for Subcatchment PR-3A: East Portion of Lot Runoff = 22.09 cfs @ 12.09 hrs, Volume= 1.820 af, Depth> 5.84" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Cornell Rainfall=6.20" Area (sf) CN Description 5,559 61 >75% Grass cover, Good, HSG B 67,368 98 Roofs, HSG B 90,014 98 Paved parkinq, HSG B 162,941 97 Weighted Average 5,559 3.41% Pervious Area 157,382 96.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-3A: East Portion of Lot Hydrograph 24" - — — — — — —I — ■Runoff 23/ 1 22.09 cfs 22�LT7 pe l U 24 � 1— — 21 — 20/i-25-yea�I he�R fai�--"o1' 4 1 + 1 I - 19_� — 17% ` ° ealI 1 2, 1ll T _1 E 7 T I E I � 16 luno=luin— e-1.—0 a - 15/H�lunoffl� pt#� H �� 4 L + w 14�— — — 13 _ .o ,in- 3 12 N==97 — M 11 — — 100 1 + 1 -1 1 --1 t 1 1 t__ 1 -1 - 6 — — — — 4 t 2 ; 4 T - 1 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type /// 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 44 Summary for Pond SSI-1: Subsurface Infiltration System 1 Inflow Area = 10.360 ac, 95.01% Impervious, Inflow Depth > 5.66" for 25-Year Cornell event Inflow = 60.51 cfs @ 12.09 hrs, Volume= 4.890 of Outflow = 8.41 cfs @ 12.61 hrs, Volume= 4.887 af, Atten= 86%, Lag= 31.2 min Discarded = 8.41 cfs @ 12.61 hrs, Volume= 4.887 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 19.99' @ 12.61 hrs Surf.Area= 14,652 sf Storage= 76,525 cf Plug-Flow detention time= 78.0 min calculated for 4.877 of(100% of inflow) Center-of-Mass det. time= 77.4 min ( 836.7 - 759.3 ) Volume Invert Avail.Storage Storage Description #1A 12.00' 40,931 cf 66.00'W x 222.00'L x 13.00'H Field A 190,476 cf Overall - 88,150 cf Embedded = 102,326 cf x 40.0% Voids #2A 14.50' 88,150 cf CMP_Round 120 x 5 Inside #1 Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.00'L Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 62.00' Header x 78.43 sf x 2 = 9,724.7 cf Inside 129,080 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 22.50' 24.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 22.50' /22.45' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf #2 Discarded 12.00' 8.270 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 8.00' Discarded OutFlow Max=8.40 cfs @ 12.61 hrs HW=19.99' (Free Discharge) L2=Exfiltration ( Controls 8.40 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.00' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) The Arsenal Project-Future Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 45 Pond SSI-1: Subsurface Infiltration System 1 - Chamber Wizard Field A Chamber Model = CMP_Round 120 (Round Corrugated Metal Pipe) Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.001 Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 120.0" Wide + 36.0" Spacing = 156.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +180.00' Row Adjustment +10.00' Header x 2 = 220.00' Row Length +12.0" End Stone x 2 = 222.00' Base Length 5 Rows x 120.0" Wide + 36.0" Spacing x 4 + 24.0" Side Stone x 2 = 66.00' Base Width 30.0" Base + 120.0" Chamber Height + 6.0" Cover = 13.00' Field Height 5 Chambers x 1,568.5 cf +180.00' Row Adjustment x 78.43 sf x 5 Rows + 62.00' Header x 78.43 sf x 2 = 88,149.7 cf Chamber Storage 190,476.0 cf Field - 88,149.7 cf Chambers = 102,326.3 cf Stone x 40.0% Voids = 40,930.5 cf Stone Storage Chamber Storage + Stone Storage = 129,080.2 cf= 2.963 of Overall Storage Efficiency = 67.8% 5 Chambers 7,054.7 cy Field 3,789.9 cy Stone The Arsenal Project-Future Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paae 46 Pond SSI-1: Subsurface Infiltration System 1 Hydrograph / — I 4— I 4 ❑ Inflow 60.51 cfs I outflow h4o�vA�e�=i O66D!a 1 1 1 1 1 1 1 1 EEl l Primary 65� / / 60-'/' / / eak- leV0 -9.919'I - 1 J_ I _ I 55 / / � r�g�e��f3'2 � L L 1 _ 50-�// 45�-/ I fi -1 films fi 401/ 35�-/ LL30� / / T T 17 TI 7 1 T I� FI � FI 20 / / 1 1 4- 1 4 -4 - 15 8.41 cfs 10� / 0.00 cfs 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type /// 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 47 Summary for Pond SSI-2: Subsurface Infiltration System 2 Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth > 5.71" for 25-Year Cornell event Inflow = 30.86 cfs @ 12.09 hrs, Volume= 2.508 of Outflow = 13.44 cfs @ 12.28 hrs, Volume= 1.996 af, Atten= 56%, Lag= 11.4 min Discarded = 0.70 cfs @ 12.28 hrs, Volume= 0.838 of Primary = 12.74 cfs @ 12.28 hrs, Volume= 1.158 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 12.37' @ 12.28 hrs Surf.Area= 14,107 sf Storage= 43,368 cf Plug-Flow detention time= 152.6 min calculated for 1.991 of(79% of inflow) Center-of-Mass det. time= 76.5 min ( 833.2 - 756.7 ) Volume Invert Avail.Storage Storage Description #1A 8.00' 18,850 cf 44.50'W x 317.00'L x 6.00'H Field A 84,639 cf Overall - 37,515 cf Embedded = 47,124 cf x 40.0% Voids #2A 8.50' 37,515 cf CMP_Round 60 x 6 Inside #1 Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 42.50' Header x 19.59 sf x 2 = 1,665.2 cf Inside 56,365 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #2 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/ Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #3 Discarded 8.00' 1.020 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 4.00' Discarded OutFlow Max=0.70 cfs @ 12.28 hrs HW=12.37' (Free Discharge) L3=Exfiltration ( Controls 0.70 cfs) Primary OutFlow Max=12.71 cfs @ 12.28 hrs HW=12.37' (Free Discharge) �__1=Culvert (Barrel Controls 6.35 cfs @ 4.04 fps) 2=Culvert (Barrel Controls 6.35 cfs @ 4.04 fps) The Arsenal Project-Future Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 48 Pond SSI-2: Subsurface Infiltration System 2 - Chamber Wizard Field A Chamber Model = CMP_Round 60 (Round Corrugated Metal Pipe) Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 60.0" Wide + 30.0" Spacing = 90.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +285.00' Row Adjustment +5.00' Header x 2 = 315.00' Row Length +12.0" End Stone x 2 = 317.00' Base Length 6 Rows x 60.0" Wide + 30.0" Spacing x 5 + 12.0" Side Stone x 2 = 44.50' Base Width 6.0" Base + 60.0" Chamber Height + 6.0" Cover = 6.00' Field Height 6 Chambers x 391.8 cf +285.00' Row Adjustment x 19.59 sf x 6 Rows + 42.50' Header x 19.59 sf x 2 = 37,514.9 cf Chamber Storage 84,639.0 cf Field - 37,514.9 cf Chambers = 47,124.1 cf Stone x 40.0% Voids = 18,849.7 cf Stone Storage Chamber Storage + Stone Storage = 56,364.5 cf= 1.294 of Overall Storage Efficiency = 66.6% 6 Chambers 3,134.8 cy Field 1,745.3 cy Stone The Arsenal Project-Future Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 49 Pond SSI-2: Subsurface Infiltration System 2 + Hydrograph + � I 1-1 t— I I —r I -1 T —t ■Inflow 30. ■Outflow + - Discarded34- /__IAo�1 A�e 5.��6� — ■Primary 30 / /Petak-EA6v��.31'1 rt 1 1 fi 1 _1 fi I r- I - 28� /—$tor�ez4"68 I ,t rt 1 1 _r 1 _1 fi I �I - 26� - 22% — I — I— — l rt � 20�' / /— I T 1 1 -r1 -1 T- rt 1 1 _r 1 _1 filrt r- I - 18; / �— 13.44 cfs — LL16� / �1T 1 T1- � 7 1 T17 TI -1 EI 1a / f— 12.74 cfs 10 / 8:/ / � I 4= 2� 0- ...�...�...�:... ......... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type /// 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 50 Summary for Pond SSI-3: Subsurface Infiltration System 3 Inflow Area = 3.578 ac, 82.30% Impervious, Inflow Depth > 5.15" for 25-Year Cornell event Inflow = 19.93 cfs @ 12.09 hrs, Volume= 1.535 of Outflow = 0.60 cfs @ 15.95 hrs, Volume= 0.712 af, Atten= 97%, Lag= 231.5 min Discarded = 0.60 cfs @ 15.95 hrs, Volume= 0.712 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 16.97' @ 15.95 hrs Surf.Area= 10,266 sf Storage= 43,556 cf Plug-Flow detention time= 319.0 min calculated for 0.710 of(46% of inflow) Center-of-Mass det. time= 199.5 min ( 979.1 - 779.6 ) Volume Invert Avail.Storage Storaqe Description #1A 11.00, 21,584 cf 87.00'W x 118.00'L x 10.00'H Field A 102,660 cf Overall - 48,699 cf Embedded = 53,961 cf x 40.0% Voids #2A 12.00' 48,699 cf CMP_Round 96 x 8 Inside #1 Effective Size= 96.0"W x 96.0"H => 50.20 sf x 20.001 = 1,004.1 cf Overall Size= 96.0"W x 96.0"H x 20.001 Row Length Adjustment= +80.00' x 50.20 sf x 8 rows 85.00' Header x 50.20 sf x 2 = 8,534.8 cf Inside 70,283 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Discarded 11.00' 1.020 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 7.00' Discarded OutFlow Max=0.60 cfs @ 15.95 hrs HW=16.97' (Free Discharge) L1=Exfiltration ( Controls 0.60 cfs) The Arsenal Project-Future Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 51 Pond SSI-3: Subsurface Infiltration System 3 - Chamber Wizard Field A Chamber Model = CMP_Round 96 (Round Corrugated Metal Pipe) Effective Size= 96.0"W x 96.0"H => 50.20 sf x 20.001 = 1,004.1 cf Overall Size= 96.0"W x 96.0"H x 20.001 Row Length Adjustment= +80.00' x 50.20 sf x 8 rows 96.0" Wide + 36.0" Spacing = 132.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +80.00' Row Adjustment +8.00' Header x 2 = 116.00' Row Length +12.0" End Stone x 2 = 118.00' Base Length 8 Rows x 96.0" Wide + 36.0" Spacing x 7 + 12.0" Side Stone x 2 = 87.00' Base Width 12.0" Base + 96.0" Chamber Height + 12.0" Cover = 10.00' Field Height 8 Chambers x 1,004.1 cf +80.00' Row Adjustment x 50.20 sf x 8 Rows + 85.00' Header x 50.20 sf x 2 = 48,698.8 cf Chamber Storage 102,660.0 cf Field -48,698.8 cf Chambers = 53,961.1 cf Stone x 40.0% Voids = 21,584.5 cf Stone Storage Chamber Storage + Stone Storage = 70,283.3 cf= 1.613 of Overall Storage Efficiency = 68.5% 8 Chambers 3,802.2 cy Field 1,998.6 cy Stone I I The Arsenal Project-Future Proposed Type 1/124-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 52 Pond SSI-3: Subsurface Infiltration System 3 Hydrograph /� I I L I —r L 1 —1 1— 1 -1 L 1 -1 -F I I -L I L 1 ❑Inflow 9.93 CfS Discarded 20� o�v A�e�3�57� �at 118 ��e�al lv � 7 - - - - - - - 1 -1 : ::1 :E I -1 -1 - 13 — 12 ° 10_ " 9_� 1 � F_ I � � I � I � I � � I � � 1 -1 —I - 8� �— - - 6 � IIII I1ICII = 4� 1JC1 � � 1 � E1 A1I � 1I 1 _ 3-/ 2= 0.60 cfs 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 53 Summary for Link POA-1: 30" Pipe Inflow Area = 10.360 ac, 95.01% Impervious, Inflow Depth = 0.00" for 25-Year Cornell event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-1: 30" Pipe Hydrograph 1 / ❑Inflow ❑Primary Inflow Area=10.360 ac N V 3 0 LL - 0.00 cfs 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 54 Summary for Link POA-2: 15" Pipe Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-2: 15" Pipe Hydrograph 1 / I❑Primary N 3 0 LL 0.00 cfs 0 6W-OV144. 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 25-Year Cornell Rainfall=6.20" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 55 Summary for Link POA-3: 18" Pipe and 24" Pipe Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth = 2.63" for 25-Year Cornell event Inflow = 12.74 cfs @ 12.28 hrs, Volume= 1.158 of Primary = 12.74 cfs @ 12.28 hrs, Volume= 1.158 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-3: 18" Pipe and 24" Pipe Hydrograph 14 17 7 I❑Pilmary� 13� Inflow Area=5.271.12.74 cfs 12� � 3 7 0 5� 3— 2L' 1� 0 �..�..�..�.. ....(. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 56 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentHDPR-3B: HD Parking Lot Runoff Area=66,885 sf 87.83% Impervious Runoff Depth>8.05" Tc=6.0 min CN=93 Runoff=12.84 cfs 1.030 of SubcatchmentPR-1A: North Portion of Runoff Area=393,607 sf 96.73% Impervious Runoff Depth>8.41" Tc=6.0 min CN=96 Runoff=76.69 cfs 6.335 of Subcatchment PR-1 B: HVMA Lot Runoff Area=155,841 sf 82.30% Impervious Runoff Depth>7.81" Tc=6.0 min CN=91 Runoff=29.50 cfs 2.328 of SubcatchmentPR-2: South Portion of Lot Runoff Area=57,681 sf 83.32% Impervious Runoff Depth>7.93" Tc=6.0 min CN=92 Runoff=11.00 cfs 0.875 of SubcatchmentPR-3A: East Portion of Lot Runoff Area=162,941 sf 96.59% Impervious Runoff Depth>8.53" Tc=6.0 min CN=97 Runoff=31.85 cfs 2.660 of Pond SSI-1: Subsurface Infiltration Peak Elev=23.66' Storage=119,101 cf Inflow=87.69 cfs 7.211 of Discarded=10.98 cfs 7.038 of Primary=4.28 cfs 0.168 of Outflow=15.26 cfs 7.206 of Pond SSI-2: Subsurface Infiltration System Peak Elev=13.95' Storage=56,105 cf Inflow=44.69 cfs 3.690 of Discarded=0.83 cfs 0.916 of Primary=21.26 cfs 2.208 of Outflow=22.09 cfs 3.123 of Pond SSI-3: Subsurface Infiltration System Peak Elev=20.73' Storage=69,181 cf Inflow=29.50 cfs 2.328 of Outflow=0.83 cfs 0.956 of Link POA-1: 30" Pipe Inflow=4.28 cfs 0.168 of Primary=4.28 cfs 0.168 of Link POA-2: 15" Pipe Primary=0.00 cfs 0.000 of Link POA-3: 18" Pipe and 24" Pipe Inflow=21.26 cfs 2.208 of Primary=21.26 cfs 2.208 of Total Runoff Area = 19.214 ac Runoff Volume = 13.229 of Average Runoff Depth = 8.26" 7.62% Pervious = 1.464 ac 92.38% Impervious = 17.749 ac The Arsenal Project-Future Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 57 Summary for Subcatchment HDPR-313: HD Parking Lot Runoff = 12.84 cfs @ 12.09 hrs, Volume= 1.030 af, Depth> 8.05" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 8,139 61 >75% Grass cover, Good, HSG B 58,746 98 Paved parkinq, HSG B 66,885 93 Weighted Average 8,139 12.17% Pervious Area 58,746 87.83% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment HDPR-313: HD Parking Lot Hydrograph 14: 12.84 cfs ❑Runoff 11� 7Qr0myea_r porhell Ryoinfa1 &PO" unofF_4r a=66,885_sf 10- �n�ff�Loi ume=1.0�0 1af-I N $ Iunpff_pe"8_05'� -k- v � Tc-6.0 T i � T 7= C"= 3 FL 5� 4-`/ 3� 2� 1� o= ... ..�..�..,. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 58 Summary for Subcatchment PR-1A: North Portion of Lot Runoff = 76.69 cfs @ 12.09 hrs, Volume= 6.335 af, Depth> 8.41" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 12,883 39 >75% Grass cover, Good, HSG A 174,583 98 Roofs, HSG A 206,141 98 Paved parkinq, HSG A 393,607 96 Weighted Average 12,883 3.27% Pervious Area 380,724 96.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1A: North Portion of Lot Hydrograph 85� i —1 -r- t— - — - O Runoff 80- 76.69 cfs _ —I 75� T�p� III 24I h r 1 _� 70=/I 190-Y( Cornell R infa11�8._0'J 4 4- 1 - 65?/ _Run Ioff_14_r a=393,6Q f - 6o�-Rlu -ff�F-i ume=6.3135 -1 -1 L 1 -1 1 -1 L I - 5o?/ Ru"fF­Pepth>8.4V- rt T_ 17 T 7 7 T_ 1 45 /-Tc-6.0 min - 0 40_�/I CN=96 fi rt - " 35-�/1— 1 ­4 1 1 4 �- 1 -� - 30?/_ _ 25-�/L I � L 1 1 LI -1 L - I _L LIB 20�'/ _ 15�,/I -1 T_ 1 --T 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 59 Summary for Subcatchment PR-1 B: HVMA Lot Runoff = 29.50 cfs @ 12.09 hrs, Volume= 2.328 af, Depth> 7.81" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 27,588 61 >75% Grass cover, Good, HSG B 18,625 98 Roofs, HSG B 109,628 98 Paved parkinq, HSG B 155,841 91 Weighted Average 27,588 17.70% Pervious Area 128,253 82.30% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-1 B: HVMA Lot Hydrograph 32�i 29.5 cfs ❑Runoff _ -- 0 30✓ 28 -T�pe II1 I�24I hr - e ornell Rainfall=8.90' 26�i-1 Q� r� � 1 � � - 24�/_Runoff_Ar a=155,84T f- 22= - - ' R1un�ff 14/o11unie=2.3Zf 20:-/1 Rlunpff_pepthP7481'�_ 18- Tc=6.0 min_ _ _ LL14� 12 I � � 10� 2� o- :... :"... .. .. ..�..�..�...�:...�:...�....,.... .. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 60 Summary for Subcatchment PR-2: South Portion of Lot Runoff = 11.00 cfs @ 12.09 hrs, Volume= 0.875 af, Depth> 7.93" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 9,621 61 >75% Grass cover, Good, HSG B 40,578 98 Roofs, HSG B 7,482 98 Paved parkinq, HSG B 57,681 92 Weighted Average 9,621 16.68% Pervious Area 48,060 83.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-2: South Portion of Lot Hydrograph �I 12- ❑Runoff � � � � 11.00 cfs T —� 111 24 h r 10�1 1 90-yeor porhell Roin fall�&PO'J 9�-Runoff7�r a=57,681 sf — - $��R�rt�fftoIame=0.815 aft Tc=6.0 min _ U - - 2�- o- :... :"... .. .. ..�..�..�...r:...�:...�....,... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 61 Summary for Subcatchment PR-3A: East Portion of Lot Runoff = 31.85 cfs @ 12.09 hrs, Volume= 2.660 af, Depth> 8.53" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Cornell Rainfall=8.90" Area (sf) CN Description 5,559 61 >75% Grass cover, Good, HSG B 67,368 98 Roofs, HSG B 90,014 98 Paved parkinq, HSG B 162,941 97 Weighted Average 5,559 3.41% Pervious Area 157,382 96.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry Subcatchment PR-3A: East Portion of Lot Hydrograph �— � � — � — � - ❑Runoff 34_ 31.85 cfs 32���� &24 hr 30 28: j 19"eor Cornell Rainfall=8.90'1 — _Runoff7Ar a=162,941 f 24��Rl,n�ff 1V/ollunie=2.6r 01 T - 22�_/�_Rm"fiff_pe P8.53" 14 I w 20, -Tc=6.0-mi n - a 16�_ fY—� I T TT T TT T L T TT 6TTTIITTTTI 2 T T - i o �:...�....�../...�..T.T.�...r:...�:...�....,...., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type /// 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 62 Summary for Pond SSI-1: Subsurface Infiltration System 1 Inflow Area = 10.360 ac, 95.01% Impervious, Inflow Depth > 8.35" for 100-Year Cornell event Inflow = 87.69 cfs @ 12.09 hrs, Volume= 7.211 of Outflow = 15.26 cfs @ 12.55 hrs, Volume= 7.206 af, Atten= 83%, Lag= 27.6 min Discarded = 10.98 cfs @ 12.55 hrs, Volume= 7.038 of Primary = 4.28 cfs @ 12.55 hrs, Volume= 0.168 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 23.66' @ 12.55 hrs Surf.Area= 14,652 sf Storage= 119,101 cf Plug-Flow detention time= 100.3 min calculated for 7.191 of(100% of inflow) Center-of-Mass det. time= 99.7 min ( 851.6 - 751.9 ) Volume Invert Avail.Storage Storage Description #1A 12.00' 40,931 cf 66.00'W x 222.00'L x 13.00'H Field A 190,476 cf Overall - 88,150 cf Embedded = 102,326 cf x 40.0% Voids #2A 14.50' 88,150 cf CMP_Round 120 x 5 Inside #1 Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.00'L Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 62.00' Header x 78.43 sf x 2 = 9,724.7 cf Inside 129,080 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 22.50' 24.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 22.50' /22.45' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf #2 Discarded 12.00' 8.270 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 8.00' Discarded OutFlow Max=10.98 cfs @ 12.55 hrs HW=23.66' (Free Discharge) L2=Exfiltration ( Controls 10.98 cfs) Primary OutFlow Max=4.27 cfs @ 12.55 hrs HW=23.66' (Free Discharge) L1=Culvert (Barrel Controls 4.27 cfs @ 3.27 fps) The Arsenal Project-Future Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 63 Pond SSI-1: Subsurface Infiltration System 1 - Chamber Wizard Field A Chamber Model = CMP_Round 120 (Round Corrugated Metal Pipe) Effective Size= 120.0"W x 120.0"H => 78.43 sf x 20.001 = 1,568.5 cf Overall Size= 120.0"W x 120.0"H x 20.001 Row Length Adjustment= +180.00' x 78.43 sf x 5 rows 120.0" Wide + 36.0" Spacing = 156.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +180.00' Row Adjustment +10.00' Header x 2 = 220.00' Row Length +12.0" End Stone x 2 = 222.00' Base Length 5 Rows x 120.0" Wide + 36.0" Spacing x 4 + 24.0" Side Stone x 2 = 66.00' Base Width 30.0" Base + 120.0" Chamber Height + 6.0" Cover = 13.00' Field Height 5 Chambers x 1,568.5 cf +180.00' Row Adjustment x 78.43 sf x 5 Rows + 62.00' Header x 78.43 sf x 2 = 88,149.7 cf Chamber Storage 190,476.0 cf Field - 88,149.7 cf Chambers = 102,326.3 cf Stone x 40.0% Voids = 40,930.5 cf Stone Storage Chamber Storage + Stone Storage = 129,080.2 cf= 2.963 of Overall Storage Efficiency = 67.8% 5 Chambers 7,054.7 cy Field 3,789.9 cy Stone The Arsenal Project-Future Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 64 Pond SSI-1: Subsurface Infiltration System 1 Hydrograph I 4— I� I 4— 4 ❑ Inflow 87.69 cfs outflow / /-166o�vAre�=_�Ut 6 a ElPrmary ed 95: / _ 851 / 80; / ' tprn_l��I%1 Q � 4 1 -k I� 1-- 4 [-- 1 75 / �� 70�;_/ / 65 / 60; 40 o 45- T 1 1 Z I 4- 4 I 4- :F- 14 �I LL 40- / 30 j 15.26 cfs 20. / 10.98 cfs 15� / 101-/ 4.28 cfs 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type /// 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 65 Summary for Pond SSI-2: Subsurface Infiltration System 2 Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth > 8.39" for 100-Year Cornell event Inflow = 44.69 cfs @ 12.09 hrs, Volume= 3.690 of Outflow = 22.09 cfs @ 12.24 hrs, Volume= 3.123 af, Atten= 51%, Lag= 9.3 min Discarded = 0.83 cfs @ 12.24 hrs, Volume= 0.916 of Primary = 21.26 cfs @ 12.24 hrs, Volume= 2.208 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 13.95' @ 12.24 hrs Surf.Area= 14,107 sf Storage= 56,105 cf Plug-Flow detention time= 126.5 min calculated for 3.117 of(84% of inflow) Center-of-Mass det. time= 61.6 min ( 811.5 - 749.9 ) Volume Invert Avail.Storage Storage Description #1A 8.00' 18,850 cf 44.50'W x 317.00'L x 6.00'H Field A 84,639 cf Overall - 37,515 cf Embedded = 47,124 cf x 40.0% Voids #2A 8.50' 37,515 cf CMP_Round 60 x 6 Inside #1 Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 42.50' Header x 19.59 sf x 2 = 1,665.2 cf Inside 56,365 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #2 Primary 10.70' 18.0" Round Culvert L= 10.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/ Outlet Invert= 10.70' / 10.60' S= 0.0100 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #3 Discarded 8.00' 1.020 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 4.00' Discarded OutFlow Max=0.83 cfs @ 12.24 hrs HW=13.95' (Free Discharge) L3=Exfiltration ( Controls 0.83 cfs) Primary OutFlow Max=21.23 cfs @ 12.24 hrs HW=13.95' (Free Discharge) �11=Culvert (Inlet Controls 10.61 cfs @ 6.01 fps) 2=Culvert (Inlet Controls 10.61 cfs @ 6.01 fps) The Arsenal Project-Future Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 66 Pond SSI-2: Subsurface Infiltration System 2 - Chamber Wizard Field A Chamber Model = CMP_Round 60 (Round Corrugated Metal Pipe) Effective Size= 60.0"W x 60.0"H => 19.59 sf x 20.001 = 391.8 cf Overall Size= 60.0"W x 60.0"H x 20.001 Row Length Adjustment= +285.00' x 19.59 sf x 6 rows 60.0" Wide + 30.0" Spacing = 90.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +285.00' Row Adjustment +5.00' Header x 2 = 315.00' Row Length +12.0" End Stone x 2 = 317.00' Base Length 6 Rows x 60.0" Wide + 30.0" Spacing x 5 + 12.0" Side Stone x 2 = 44.50' Base Width 6.0" Base + 60.0" Chamber Height + 6.0" Cover = 6.00' Field Height 6 Chambers x 391.8 cf +285.00' Row Adjustment x 19.59 sf x 6 Rows + 42.50' Header x 19.59 sf x 2 = 37,514.9 cf Chamber Storage 84,639.0 cf Field - 37,514.9 cf Chambers = 47,124.1 cf Stone x 40.0% Voids = 18,849.7 cf Stone Storage Chamber Storage + Stone Storage = 56,364.5 cf= 1.294 of Overall Storage Efficiency = 66.6% 6 Chambers 3,134.8 cy Field 1,745.3 cy Stone The Arsenal Project-Future Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 67 Pond SSI-2: Subsurface Infiltration System 2 Hydrograph ■Inflow — 44.69 cfs I — — - ■outflow 50_ / �I41o�vA�e65.2f6'a� ;Discarded 45�'/ 40� / /_$torage;�5M QI5 cfs I J_ t- -4 � 30�Z ,—I t I r I -1 t- 22.09 cfs 25� ° / � I I I I I I I I 21.26 cfs u. 20� / I I I I 15� — 5L­ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type /// 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Page 68 Summary for Pond SSI-3: Subsurface Infiltration System 3 Inflow Area = 3.578 ac, 82.30% Impervious, Inflow Depth > 7.81" for 100-Year Cornell event Inflow = 29.50 cfs @ 12.09 hrs, Volume= 2.328 of Outflow = 0.83 cfs @ 16.08 hrs, Volume= 0.956 af, Atten= 97%, Lag= 239.5 min Discarded = 0.83 cfs @ 16.08 hrs, Volume= 0.956 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 20.73' @ 16.08 hrs Surf.Area= 10,266 sf Storage= 69,181 cf Plug-Flow detention time= 337.4 min calculated for 0.954 of(41% of inflow) Center-of-Mass det. time= 203.1 min ( 972.3 - 769.2 ) Volume Invert Avail.Storage Storaqe Description #1A 11.00, 21,584 cf 87.00'W x 118.00'L x 10.00'H Field A 102,660 cf Overall - 48,699 cf Embedded = 53,961 cf x 40.0% Voids #2A 12.00' 48,699 cf CMP_Round 96 x 8 Inside #1 Effective Size= 96.0"W x 96.0"H => 50.20 sf x 20.001 = 1,004.1 cf Overall Size= 96.0"W x 96.0"H x 20.001 Row Length Adjustment= +80.00' x 50.20 sf x 8 rows 85.00' Header x 50.20 sf x 2 = 8,534.8 cf Inside 70,283 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routinq Invert Outlet Devices #1 Discarded 11.00' 1.020 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 7.00' Discarded OutFlow Max=0.83 cfs @ 16.08 hrs HW=20.73' (Free Discharge) L1=Exfiltration ( Controls 0.83 cfs) The Arsenal Project-Future Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 69 Pond SSI-3: Subsurface Infiltration System 3 - Chamber Wizard Field A Chamber Model = CMP_Round 96 (Round Corrugated Metal Pipe) Effective Size= 96.0"W x 96.0"H => 50.20 sf x 20.001 = 1,004.1 cf Overall Size= 96.0"W x 96.0"H x 20.001 Row Length Adjustment= +80.00' x 50.20 sf x 8 rows 96.0" Wide + 36.0" Spacing = 132.0" C-C Row Spacing 1 Chambers/Row x 20.00' Long +80.00' Row Adjustment +8.00' Header x 2 = 116.00' Row Length +12.0" End Stone x 2 = 118.00' Base Length 8 Rows x 96.0" Wide + 36.0" Spacing x 7 + 12.0" Side Stone x 2 = 87.00' Base Width 12.0" Base + 96.0" Chamber Height + 12.0" Cover = 10.00' Field Height 8 Chambers x 1,004.1 cf +80.00' Row Adjustment x 50.20 sf x 8 Rows + 85.00' Header x 50.20 sf x 2 = 48,698.8 cf Chamber Storage 102,660.0 cf Field -48,698.8 cf Chambers = 53,961.1 cf Stone x 40.0% Voids = 21,584.5 cf Stone Storage Chamber Storage + Stone Storage = 70,283.3 cf= 1.613 of Overall Storage Efficiency = 68.5% 8 Chambers 3,802.2 cy Field 1,998.6 cy Stone I I The Arsenal Project-Future Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 70 Pond SSI-3: Subsurface Infiltration System 3 Hydrograph X�r— I4 ❑Inflow O CfS 0 30?/ 'JJ n Oo V'A' ea--i1J/ p Discarded 26 e�al �e�v 2� 3 - T T 26�' 24— �-/ /$tir 6060;181 6f 20-:L � 3 16_ LL14-' 12?/ 10-�/ � 8_ - - � I 4 J/2- - 0.83 cfs .................... ... .... .... ... ... ... ...�...�...(....�...�...�...�..., 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 1/124-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCADO 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 71 Summary for Link POA-1: 30" Pipe Inflow Area = 10.360 ac, 95.01% Impervious, Inflow Depth = 0.19" for 100-Year Cornell event Inflow = 4.28 cfs @ 12.55 hrs, Volume= 0.168 of Primary = 4.28 cfs @ 12.55 hrs, Volume= 0.168 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-1: 30" Pipe Hydrograph IIII l llll Inflow 4.28 cfs — ❑Primary In� oroA e .3G 4 IIIIIIIIIII IIIIIIIIII I -1 LIB _LI —I L LI I LI I LI _J _LI _ 3 IIIIIII I � IIIIIIII I- I - 3 0 " 2 IIIIIIII 1 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 72 Summary for Link POA-2: 15" Pipe Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-2: 15" Pipe Hydrograph 1-/ I❑Primary N 3 0 LL 0.00 cfs 0 6W-OV144. 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) The Arsenal Project-Future Proposed Type 111 24-hr 100-Year Cornell Rainfall=8.90" Prepared by RJO'Connell & Associates, Inc. Printed 6/14/2016 HydroCAD® 10.00-12 s/n 04881 ©2014 HydroCAD Software Solutions LLC Paqe 73 Summary for Link POA-3: 18" Pipe and 24" Pipe Inflow Area = 5.276 ac, 94.04% Impervious, Inflow Depth = 5.02" for 100-Year Cornell event Inflow = 21.26 cfs @ 12.24 hrs, Volume= 2.208 of Primary = 21.26 cfs @ 12.24 hrs, Volume= 2.208 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link POA-3: 18" Pipe and 24" Pipe Hydrograph - 112 ❑Inflow 23 �— � 21�26 cfs � � � � � 0 Primary 2, �Inlow Are -s2 — — — 20 � 14 I � 4- I 1 I- 14 � I � I —1 + I- 19 V -- - — 16/ ,— 15. 13 I T — — 12� � IL 9V — — 8 7�% � I4 � I -44- I 1T 14 I � � I 1 1� 6 4 - - - - - I I - I - -1 — —I - I_ 3 2" 1 o �..�..�..�..�..i...�... 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) III. APPENDIX E Performance Data Massachusetts Stormwater Handbook Table TSS TSS Removal Efficiencies for Best Management Practices Best Management Practice TSS Removal Efficiency (BMP) Non-Structural Pretreatment BMPs Street Sweeping 0710%, See Volume 2, Chapter 1. Structural Pretreatment BMPs Deep Sump Catch Basins 25%only if used for pretreatment and only if off-line Oil Grit Separator 25%only if used for pretreatment and only if off-line Proprietary Separators Varies—see Volume 2, Chapter 4. Sediment Forebays 25% if used for pretreatment Vegetated filter strips 10% if at least 25 feet wide, 45% if at least 50 feet wide Treatment BMPs Bioretention Areas including 90% provided it is combined with adequate pretreatment rain gardens Constructed Stormwater 80% provided it is combined with a sediment forebay Wetlands Extended Dry Detention Basins 50% provided it is combined with a sediment forebay Gravel Wetlands 80% provided it is combined with a sediment forebay Proprietary Media Filters Varies—see Volume 2, Chapter 4 Sand/Organic Filters 80% provided it is combined with sediment forebay Treebox filter 80% provided it is combined with adequate pretreatment Wet Basins 80% provided it is combined with sediment forebay Conveyance Drainage Channels For conveyance only. No TSS Removal credit. Grass Channels (formerly 50% if combined with sediment forebay or equivalent biofilter swales) Water Quality Swale— 70% provided it is combined with sediment forebay or equivalent wet&dry Infiltration BMPs Dry Wells 80%for runoff from non-metal roofs; may also be used for runoff from metal roofs but only if metal roof is not located within a Zone II, or IWPA or at an industrial site Infiltration Basins&Infiltration 80% provided it is combined with adequate pretreatment(sediment forebay or Trenches vegetated filter strip, grass channel, water quality swale)prior to infiltration Leaching Catch Basins 80% provided a deep sump catch basin is used for pretreatment Subsurface Structure 80% provided they are combined with one or more pretreatment BMPs prior to infiltration. Other BMPs Dry Detention Basins For peak rate attenuation only. No TSS Removal credit. Green Roofs See Volume 2. Chapter 2. May reduce required water quality volume. No TSS Removal Credit. Porous Pavement 80%if designed to prevent runon and with adequate storage capacity. Limited to uses identified in Volume 2, Chapter 2. Rain Barrels and Cisterns May reduce required water quality volume. No TSS Removal Credit. Volume 1:Overview of Massachusetts Stormwater Standards Chapter 1 Page 11 Massachusetts Stormwater Handbook Better Site Design: A Handbook for Changing Development Rules in Your Community; Center for Watershed Protection; 1998. Site Planning for Urban Stream Protection; Thomas Schueler; Center for Watershed Protection; 1995. Conservation Design for Subdivisions: A Practical Guide for Creating Open Space Networks; Randall Arendt; Island Press; 1996. "Site Analysis."James A. LaGro,Jr.; John Wiley and Sons; 2001 An Introduction to Better Site Design; Article 45 from Watershed Protection Techniques; Center for Watershed Protection; 2000. B. Nonstructural Approaches: Source Control and Pollution Prevention Source controls can reduce the types and concentrations of contaminants in stormwater runoff and improve water quality. Source controls cover a wide range of practices including local bylaws and regulations,materials management at industrial sites, fertilizer and pest management in residential areas,reduced road salting in winter, erosion and sediment controls at construction sites,and comprehensive snow management. Effective site planning is essential to source control and pollution prevention. Reducing impervious surfaces and runoff volumes prevents the transport of pollutants. The guiding principle for pollution prevention is to minimize the volume of runoff and the contact of stormwater with potential pollutants. Because nonstructural practices can reduce stormwater pollutant loads and quantities,the size and expense of structural BMPs(or in rare cases, even the need for structural BMPs) can be reduced,thereby affording substantial cost savings. The Massachusetts Nonpoint Pollution Source Management Manual (http://www.mass.aov/deo/water/resources/nonvoint.htm#me2aman)published by MassDEP (2006)provides a detailed summary of the pollutants associated with specific land use activities. These summaries can be used to identify the potential pollutants at a site, so that suitable controls can be implemented. Street and Parking Lot Sweeping One effective nonstructural source control is street and parking lot sweeping. Many municipalities and some private entities(e.g.,commercial shopping areas or office parks)have street sweeping programs. Although intended to provide important nonpoint source pollution control,many street sweeping programs are not effective at capturing the peak sediment loads. The NURP study(EPA, 1983)indicates that sweeping streets once a year using rotary brush sweepers resulted in no TSS removal. A study conducted by the USGS (Smith, 2002) along the Southeast Expressway in Boston indicates that sweeping yielded a net increase in sediment, because the road shoulder was not stabilized and contributed more sediment to the Southeast Expressway than the sweepers could remove. There are many reasons that some street sweeping programs are not effective. Volume 2:Technical Guide for Compliance with the Massachusetts Chapter 1 Page 7 Stormwater Management Standards Massachusetts Stormwater Handbook o The period immediately following winter snowmelt,when road sand and other accumulated sediment and debris is washed off,is frequently missed by street sweeping programs. o Larger particles of street dirt may prevent smaller particles from being collected. o The entire width of roadway may not be swept. o Sweepers may be driven too quickly to achieve maximum efficiency. o Land surfaces along the paved surfaces may not be entirely stabilized. Other studies have shown that if done properly, street sweeping can be highly effective. Breault 2005 indicates that sweepers can achieve high removal efficiencies. That study assessed total solids removal, and included large particles. Zarriello 2002 verified the effectiveness of high efficiency sweepers. There are three factors in particular that can have a major influence on the effectiveness of a street sweeping program: access,the type of sweeper, and the frequency of sweeping. Effective sweeping requires access to the areas to be swept. Parked cars impede street sweeping. Studies have shown that up to 95%of the solids on a paved surface accumulate within 40 inches of the curb,regardless of land use. It is essential that applicants or those responsible for stormwater maintenance have the ability to impose parking regulations to facilitate proper sweeping,particularly in densely populated or heavily traveled areas, so that sweepers can get as close to curbs as possible. A good street sweeping program requires an efficient sweeper. There are three types of sweepers: Mechanical,Regenerative Air, and Vacuum Filter. Each has a different ability to remove TSS. • Mechanical: Mechanical sweepers use brooms or rotary brushes to scour the pavement. Although most of the sweepers currently in use in Massachusetts are mechanical sweepers,they are not effective at removing TSS (from 0%to 20%removal). Mechanical sweepers are especially ineffective at picking up fine particles ("fines") (less than 100 microns). • Regenerative Air: These sweepers blow air onto the road or parking lot surface, causing fines to rise where they are vacuumed. Regenerative air sweepers may blow fines off the vacuumed portion of the roadway or parking lot,where they contaminate stormwater when it rains. • Vacuum filter: These sweepers remove fines along roads. Two general types of vacuum filter sweepers are available-wet and dry. The dry type uses a broom in combination with the vacuum. The wet type uses water for dust suppression. Research indicates vacuum sweepers are highly effective in removing TSS. The best ones (in terms of pollutant removal efficiencies)typically cost about$240,000 to $310,000. Regardless of the type chosen,the efficiency of street sweeping is increased when sweepers are operated in tandem. The frequency of sweeping is a major factor in determining efficiency. Unlike other stormwater treatment practices that function whenever it rains, street sweeping only picks up street dirt when streets and parking lots are actually swept. TSS removal efficiency is determined based on annual loading rates. If a road were swept only once a year with a sweeper that is 100% efficient, it would remove only a small fraction of the annual TSS load. Volume 2:Technical Guide for Compliance with the Massachusetts Chapter 1 Page 8 Stormwater Management Standards Massachusetts Stormwater Handbook Street dirt accumulates on roads and parking lots and runs off in response to precipitation. The average interval between precipitation events in Massachusetts is approximately 3 days. Therefore,the hypothetical maximum effectiveness for street dirt removal requires sweeping at least once every 3 days,with a street sweeper with 100%efficiency at removing solids on paved surfaces before they become suspended. Modeling studies by Claytor(1999)in the Pacific Northwest suggest that optimum pollutant removal occurs when surfaces are swept every two weeks. Because street sweeping may be an effective source reduction tool, a credit towards the 80%TSS removal standard may be available.At the discretion of the issuing authority, a street sweeping program is eligible to receive credit towards the 80% TSS removal standard as set forth in the Table SS 1. TSS REMOVAL CREDITS FOR STREET SWEEPING Table SS 1 TSS High Efficiency Vacuum Regenerative Air Mechanical Sweeper Removal Sweeper—Frequency of Sweeper—Frequency of (Rotary Broom) Rate Sweeping Sweeping 10% Monthly Average,with Every 2 Weeks Average, Weekly Average,with sweeping scheduled with sweeping scheduled sweeping scheduled primarily in spring and primarily in spring and primarily in spring and fall. fall. fall. 5% Quarterly Average,with Quarterly Average,with Monthly Average,with sweeping scheduled sweeping scheduled sweeping scheduled primarily in spring and primarily in spring and primarily in spring and fall. fall. fall. 0% Less than above Less than above Less than above Street sweeping is not recommended as a practice to receive a TSS removal credit for post- construction period runoff, if the road or parking lot shoulders are not stabilized. All TSS Removal Credits shown in Table SS I assume that the sweeping program gives special attention to sweeping paved surfaces in March/April before spring rains wash residual sand from winter applications into streams. If this assumption is not correct, the issuing authority should reduce the TSS removal credit by 50%. Planning Considerations In deciding whether street sweeping is an effective option,consider factors such as whether road and parking lot shoulders are stabilized,the speed at which the sweepers will need to be driven (safety factor such as along a highway),whether access is available to the curb(whether vehicles parked along the curb line will preclude sweeping of the curb line),the type of sweepers, and whether the sweepers will be operated in tandem. Municipalities or private developers that are planning to purchase a new street sweeper should consider vacuum sweepers,because they are most consistently effective. Maintenance Reuse and Disposal of Street Sweepings Volume 2:Technical Guide for Compliance with the Massachusetts Chapter 1 Page 9 Stormwater Management Standards Massachusetts Stormwater Handbook Once removed from paved surfaces,the sweeping must be handled and disposed of properly. MassDEP's Bureau of Waste Prevention has issued a written policy regarding the reuse and disposal of street sweepings. These sweepings are regulated as a solid waste, and can be used in three ways: • In one of the ways already approved by MassDEP(e.g.,daily cover in a landfill, additive to compost, fill in a public way) • If approved under a Beneficial Use Determination • Disposed in a landfill MassDEP provides guidance and standards for handling,reusing, and disposing of street sweepings. (For more information, go to: www.mass.2ov/der)/recvcle/laws/stsween.htm) Sources: • American Sweeper Magazine. Non-peer review magazine. Link: httr)://www.nasweei)er.com/ • Bannerman,Roger, 1999, Sweeping Water Clean,American Sweeper Magazine,Volume 7,Number 1. • Breault,Robert F., Smith,Kirk P. and Sorenson, Jason R.,2005,Residential Street-Dirt Accumulation Rates and Chemical Composition, and Removal Efficiencies by Mechanical-and Vacuum-Type Sweepers,New Bedford,Massachusetts,2003-04 • U.S. Geological Survey, Scientific Investigations Report 2005-5184, h"://l)ubs.usas.2ov/sir/2005/5184/ • Brinkmann et al, 1999, Chemical and Physical Characteristics of Street Sweeping Sediments in Tampa,Florida, httn://www.hinklevicenter.com/publications/characteristics of street sweenin2 98- 12 pdf - - - • California Department of Transportation,Fact Sheet SC-7,2003: httn://www.dot.ca.2ov/hci/construc/sormwater/SC-07.1)df • Center for Watershed Protection,Pollution Prevention Fact Sheet: Parking Lot and Street Cleaning, htti)://www.ston,nwatercenter.net/Pollution Prevention Factsheets/Parkin2LotandStreetC leanina.htm • Fitz,D.R., 1998,Evaluation of Street Sweenina as a PM10 Control Method. Other Documents and Presentations. Final Report to the South Coast Air Quality Management District under Contract 96018,January. 98-AP-RT4H-005-FR. • Hamilton, City of, Ontario, Canada, 1998,unpublished study, htto://www.cleanair.hamilton.ca/about/sweer)in2.asi) • Keating,Janis,2002, Street Sweepers,Picking Up Speed and Quieting Down,Keating, Stormwater- The Journal for Surface Water Quality Professionals, httn://www.forester.net/sw0207 street.html • Martinelli, Thomas J.,Waschbusch,R.J.,Bannerman,R.T.,Wisner,A., 2002,Pollutant Loadings to Stormwater Run-off from Highways: the Impact of a Freeway Sweeping Program,Wisconsin Department of Transportation,Research Project ID#0092-45-82, Report WI-11-01,httn://www.dot.wisconsin.2ov/librarv/research/docs/finalrel)orts/45- 82sweePin2-fxdf and http://www.dot.wisconsin.2ov/librar_v/research/docsibriefs/45- 82freewaysweevin2-b.vdf • Metropolitan Council, 1999,Best Practices for Street Sweeping,American Sweeper Magazine,Volume 7,Number 1: httn://www.worldsweener.com/Street/BestPractices/bestr)ract.html Volume 2:Technical Guide for Compliance with the Massachusetts Chapter 1 Page 10 Stormwater Management Standards Deep Sump Catch Basin escription: Deep sump catch basins, also known as oil and grease or hooded catch basins, are underground retention systems designed to remove trash, debris, and coarse sediment from stormwater runoff, and serve as mporary spill containment devices r floatables such as oils and greases. Ability to meet specific stems Advantages/Benefits: • Located underground, so limited lot size is Standard Description not a deterrent. 2 - Peak Flow Provides no peak flow attenuation • Compatible with subsurface storm drain systems. 3- Recharge Provides no groundwater recharge . Can be used for retrofitting small urban lots 4-TSS Removal 25%TSS removal credit when where larger BMPs are not feasible. used for pretreatment. Because • Provide pretreatment of runoff before it is of their limited effectiveness and delivered to other BMPs. storage capacity, deep sump catch • Easily accessed for maintenance. basins receive credit for removing • Longevity is high with proper maintenance. TSS only if they are used for pretreatment and designed as off- Disadvantages/Limitations: line systems. • Limited pollutant removal. 5 - Higher Recommended as pretreatment • Expensive to install and maintain, resulting in Pollutant BMP.Although provides some spill high cost per unit area treated. Loading control capability,a deep sump • No ability to control volume of stormwater catch basin may not be used in • Frequent maintenance is essential place of an oil grit separator or sand - Requires proper disposal of trapped sediment filter for land uses that have the and oil and grease potential to generate runoff with • Entrapment hazard for amphibians and other high concentrations of oil and grease small animals such as: high-intensity-use parking pollutant Removal Efficiencies lots,gas stations, fleet storage • Total Suspended Solids (TSS) - 25% (for areas,vehicle and/or equipment regulatory purposes) maintenance and service areas. • Nutrients (Nitrogen, phosphorus) - 6 - Discharges May be used as pretreatment BMP. Insufficient data near or to not an adequate spill control device • Metals (copper, lead, zinc, cadmium) - Critical Areas for discharges near or to critical Insufficient data areas. _ _ _ • Pathogens (coliform, e coli) - Insufficient 7 - Highly suitable. I data Redevelopment Structural BMPs- Volume 2 1 Chapter page 2 GRANITE CURB/CURB INLET FRAME AND GRATE, 3 FLANGE RIM FINISHED GRADE LEBARON CATALOG NO LF248-2 OR EQUAL 4�, 2- (SEE NOTE 7) MORTAR 3 SIDES WHERE CURB/CURB INLET EXISTS, g" h 4 SIDES WHEN WITHOUT CURB/CURB INLET FLAT TOP :,..::� .'; `,;' ADJUST TO GRADE WITH A MIN TWO COURSES 2,—d. SECTION I- wID� (5 MAX) BRICK MASONRY IN FULL MORTAR BED LL PROVIDE CATCH BASIN HOOD LEBARQN ° o 48p DIA TYP CATALOG NO L--202 OR EQUAL TO _ ) MATCH DIMENSION OF OUTFLOW PIPE iY w OUTSIDE DIA OF PIPE z f2" CLEARANCE NON—SHRINK MORTAR ALL AROUND f MASTIC GASKET i (TYP ALL JOINTS AND 2 LIFTING HOLES) 5" (MIN) (MIN) PRECAST REINFORCED CONCRETE SECT'ION5 c o TO CONFORM TO ASTM C-478, CONCRETE OF E„ CRUSHED 4000 PSI IN 28 DAYS ROCK (MIN)— adapted from the University of New Hampshire Maintenance Activity Frequency Inspect units Four times per year Clean units Four times per year or whenever the depth of deposits is greater than or equal to one half the depth from the bottom of the invert of the lowest pipe in the basin. Special Features All deep sump catch basins must include hoods. For MassHighway projects, consult the Stormwater Handbook for Highways and Bridges for hood requirements. LID Alternative Reduce Impervious Surface Disconnect rooftop and non-rooftop runoff Vegetated Filter Strip Structural BMPs- Volume 2 1 Chapter 2 page 3 Deep Sump Catch Basin management controls. Inlet grates inside parking garages are currently required to have much smaller openings than those described herein. Suitable Applications • Pretreatment To receive the 25%removal credit, hoods must • Residential subdivisions be used in deep sump catch basins. Hoods also • Office help contain oil spills. MassHighway may install • Retail catch basins without hoods provided they are designed, constructed, operated, and maintained Design Considerations in accordance with the Mass Highway Stormwater • The contributing drainage area to any deep Handbook. sump catch basin should not exceed '/a acre of impervious cover. Install the weep hole above the outlet pipe. Never • Design and construct deep sump catch basins as install the weep hole in the bottom of the catch basin off-line systems. barrel. • Size the drainage area so that the flow rate does not exceed the capacity of the inlet grate. Site Constraints • Divert excess flows to another BMP intended A proponent may not be able to install a deep sump to meet the water quantity requirements (peak catch basin because of: rate attenuation) or to a storm drain system. • Depth to bedrock; An off-line design enhances pollutant removal • High groundwater; efficiency, because it prevents the resuspension • Presence of utilities; or of sediments in large storms. • Other site conditions that limit depth of excavation because of stability. Make the sump depth (distance from the bottom of the outlet pipe to the bottom of the basin) at least Maintenance four feet times the diameter of the outlet pipe and Regular maintenance is essential. Deep sump catch more if the contributing drainage area has a high basins remain effective at removing pollutants only sediment load. The minimum sump depth is 4 feet. if they are cleaned out frequently. One study found Double catch basins, those with 2 inlet grates, may that once 50% of the sump volume is filled, the catch require deeper sumps. Install the invert of the outlet basin is not able to retain additional sediments. pipe at least 4 feet from the bottom of the catch basin grate. Inspect or clean deep sump basins at least four times per year and at the end of the foliage and snow- The inlet grate serves to prevent larger debris from removal seasons. Sediments must also be removed entering the sump. To be effective, the grate must four times per year or whenever the depth of deposits have a separation between the grates of one square is greater than or equal to one half the depth from inch or less. The inlet openings must not allow flows the bottom of the invert of the lowest pipe in the greater than 3 cfs to enter the deep sump catch basin. basin. If handling runoff from land uses with higher If the inlet grate is designed with a curb cut, the potential pollutant loads or discharging runoff near grate must reach the back of the curb cut to prevent or to a critical area, more frequent cleaning may be bypassing. The inlet grate must be constructed necessary. of a durable material and fit tightly into the frame so it won't be dislodged by automobile traffic. The Clamshell buckets are typically used to remove inlet grate must not be welded to the frame so that sediment in Massachusetts. However, vacuum sediments may be easily removed. To facilitate trucks are preferable, because they remove more maintenance, the inlet grate must be placed along trapped sediment and supernatant than clamshells. the road shoulder or curb line rather than a traffic Vacuuming is also a speedier process and is less lane. likely to snap the cast iron hood within the deep sump catch basin. Note that within parking garages, the State Plumbing Code regulates inlet grates and other stormwater Structural BMPs- Volume 2 1 Chapter page 4 Always consider the safety of the staff cleaning deep sump catch basins. Cleaning a deep sump catch basin within a road with active traffic or even within a parking lot is dangerous, and a police detail may be necessary to safeguard workers. Although catch basin debris often contains concentrations of oil and hazardous materials such as petroleum hydrocarbons and metals, MassDEP classifies them as solid waste. Unless there is evidence that they have been contaminated by a spill or other means, MassDEP does not routinely require catch basin cleanings to be tested before disposal. Contaminated catch basin cleanings must be evaluated in accordance with the Hazardous Waste Regulations, 310 CMR 30.000, and handled as hazardous waste. In the absence of evidence of contamination, catch basin cleanings may be taken to a landfill or other facility permitted by MassDEP to accept solid waste, without any prior approval by MassDEP. However, some landfills require catch basin cleanings to be tested before they are accepted. With prior MassDEP approval, catch basin cleanings may be used as grading and shaping materials at landfills undergoing closure (see Revised Guidelines for Determining Closure Activities at Inactive Unlined Landfill Sites) or as daily cover at active landfills. MassDEP also encourages the beneficial reuse of catch basin cleanings whenever possible. A Beneficial Reuse Determination is required for such use. MassDEP regulations prohibit landfills from accepting materials that contain free-draining liquids. One way to remove liquids is to use a hydraulic lift truck during cleaning operations so that the material can be decanted at the site. After loading material from several catch basins into a truck, elevate the truck so that any free-draining liquid can flow back into the structure. If there is no free water in the truck, the material may be deemed to be sufficiently dry. Otherwise the catch basin cleanings must undergo a Paint Filter Liquids Test. Go to www. Mass.gov/dep/ recycle/laws/cafacts.doc for information on all of the MassDEP requirements pertaining to the disposal of catch basin cleanings. Structural BMPs- Volume 2 Chapter page 5 Oil/Grit Separators Description: Oil/grit separators are underground storage tanks with three chambers designed to remove heavy particulates,floating debris and hydrocarbons from stormwater. Stormwater enters the first chamber where heavy sediments and solids drop out. The flow moves into the second chamber where oils and greases are removed and further settling of suspended solids takes place. Oil and grease are stored in this second chamber for future removal. After moving into the third outlet chamber, the clarified stormwater runoff is then discharged to a pipe and another BMP. There are other separators that may be used for spill control. Ability to meet specific standards • Located underground so limited lot size not a Standard Description deterrent in urban areas with small lots 2 - Peak Flow Provides no peak flow • Can be used for retrofits attenuation • Can be installed in any soil or terrain. 3 - Recharge Provides no groundwater • Public safety risks are low. recharge 4 - TSS 25%TSS removal credit when Disadvantages/Limitations: Removal used for pretreatment and placed • Limited pollutant removal; cannot effectively off-line. remove soluble pollutants, fine particles, or 5 - Higher MassDEP requires a pretreatment bacteria Pollutant BMP, such as an oil/grit separator • Can become a source of pollutants due to Loading that is capable of removing oil resuspension of sediment unless properly and grease, for land uses with maintained higher potential pollutant loads where there is a risk of petroleum • Susceptible to flushing during large storms spills such as: high intensity use • Limited to relatively small contributing drainage parking lots, gas stations, fleet areas storage areas,vehicle and/or • Requires proper disposal of trapped sediments and equipment maintenance and oils service areas. • May be expensive to construct and maintain 6 - Discharges May be a pretreatment BMP when • Entrapment hazard for amphibians and other small near or to combined with other practices. animals Critical Areas May serve as a spill control device. 7 - Highly suitable. Pollutant Removal Efficiencies Redevelopment • Total Suspended Solids (TSS) - 25%for oil grit separator, only when placed off-line and only when used for pretreatment • Nutrients (Nitrogen, phosphorus) - Insufficient data • Metals (copper, lead, zinc, cadmium) - Insufficient data • Pathogens (coliform, e coli) - Insufficient data Structural BMPs- Volume 2 1 Chapter page 6 Taft DPAIN ACCESS INIET r*r��aLEs or air 'LL- . 111 cMED CLaa* PIPE REOUVA`CS Yaa(R IE fLS OhERFLCNr T ,f PIPE y+ CROCE, � • A y i �CCUMUlAIFD SEIDWINI + of A riRST cWAu9ER Sf!MND CRAMBEP THIRD CRWIDER (SEaI64EN'T TRAPMG) (Oil SEPE 0111) MassRighwav 2004 Maintenance Activity Frequency Inspect units After every major storm but at least monthly Clean units Twice a year Structural BMPs- Volume 2 1 Chapter page 7 Oil/Grit Separators of the elbow pipe at least 3 feet below the second chamber's permanent pool. • Provide appropriate removal covers that allow Applicability access for observation and maintenance. Oil grit separators must be used to manage runoff . Where the structure is located below the from land uses with higher potential pollutant seasonal high groundwater table, design the loads where there is a risk that the stormwater is structure to prevent flotation. contaminated with oil or grease. These uses include • For gas stations, automobile maintenance and the following: service areas, and other areas where large volumes of petroleum and oil are handled, • High-Intensity-Use Parking Lots consider adding coalescing plates to increase • Gas Fueling Stations the effectiveness of the device and reduce the • Vehicles (including boats, buses, cars, and trucks) size of the units.A series of coalescing plates and Equipment Service and Maintenance Areas constructed of oil-attracting materials such as • Fleet Storage Areas polypropylene typically spaced one inch apart attracts small droplets of oil, which begin to Design Considerations concentrate until they are large enough to float to the surface. • Dovetail design practices, source controls and pollution prevention measures with separator Maintenance design. Sediments and associated pollutants and trash are • Place separators before all other structural removed only when inlets or sumps are cleaned stormwater treatment practices (except for out, so regular maintenance is essential. Most structures associated with source control/ studies have linked the failure of oil grit separators pollution prevention such as drip pans and to the lack of regular maintenance. The more structural treatment practices such as deep sump frequent the cleaning, the less likely sediments catch basins that double as inlets). will be resuspended and subsequently discharged. • Limit the contributing drainage area to the oil/grit In addition, frequent cleaning also makes more separator to one acre or less of impervious cover. volume available for future storms and enhances • Use oil grit separators only in off-line overall performance. Cleaning includes removal configurations to treat the required water quality of accumulated oil and grease and sediment volume. using a vacuum truck or other ordinary catch • Provide pool storage in the first chamber to basin cleaning device. In areas of high sediment accommodate the required water quality volume loading, inspect and clean inlets after every major or 400 cubic feet per acre of impervious surface. storm. At a minimum, inspect oil grit separators Confirm that the oil/grit separator is designed to monthly, and clean them out at least twice per year. treat the required water quality volume. Polluted water or sediments removed from an oil • Make the permanent pool at least 4 feet deep. grit separator should be disposed of in accordance • Design the device to pass the 2-year 24-hour with all applicable local, state and federal laws and storm without interference and provide a bypass regulations including M.G.L.c. 21C and 310 CMR 30.00. for larger storms to prevent resuspension of solids. • Make oil/grit separator units watertight to prevent possible groundwater contamination. • Use a trash rack or screen to cover the discharge outlet and orifices between chambers. • Provide each chamber with manholes and access stepladders to facilitate maintenance and allow cleaning without confined space entry. • Seal potential mosquito entry points. • Install any pump mechanism downstream of the separator to prevent oil emulsification. • Locate an inverted elbow pipe between the second and third chambers and with the bottom Structural BMPs- Volume 2 Chapter page 8 References: American Petroleum Institute, 2002, Management of Water Discharges: Design and Operations of Oil-Water Separators, 1st Edition, Revision 90,American Petroleum Institute. Arizona Department of Environmental Quality, 1996, BADCT Guidance Document for Pretreatment with Oil/ Water Separators, OFR 96-15, http://www.azdeq.gov/environ/water/permits/download/0wsbadct.pdf Beychok, Milton, Wikipedia, API Oil-Water Separator, http://en.wikipedia.org/wiki/API-oil-water-separator Center for Watershed Protection, Performance of Oil-Grit Separators in Removing Pollutants at Small Sites, Technical Note #101 from Watershed Protection Techniques. 2(3): 539-542 Houston, City of, Harris County, Harris County Flood Control District, 2001, Storm Water Quality Management Guidance Manual, Section 4.4.2, p. 4-84 to 4-89, http://www.cleanwaterclearchoice.org/downloads/ professional/guidance_manual_full.pdf Idaho Department of Environmental Quality, 2005, Storm Water Best Management Practices Catalog, Oil/ Water Separator, BMP 18, pp. 91 to 95, http://www.deq.idaho.gov/water/data_reports/storm water/catalog/ sec_4/bmps/18.pdf Massachusetts Highway Department, 2004, Storm Water Handbook for Highways and Bridges, p. Minton, Gary. 2002, Stormwater Treatment, RPA Associates, Seattle, WA, p. 120 New Zealand Water Environment Research Foundation, 2004, On-Site Stormwater Management Guideline, Section 5.10, pp. 23 to 24, http://www.nzwwa.org.nz/Section%205.pdf Schueler, T.R., 1987, Controlling Urban Runoff:A Practical Manual for Planning and Designing Urban BMPs, Metropolitan Washington Council of Governments, Washington, DC. U.S. EPA, 1999, Storm Water Technology Fact Sheet,Water Quality Inlets, EPA 832-F-99-029, http://www.epa.gov/owm/mtb/wtrqlty.pdf Structural BMPs- Volume 2 1 Chapter page 9 Subsurface Structures 1 4' escription: Subsurface structures are underground x ystems that capture runoff, and gradually infiltrate it into the ., roundwater through rock and gravel. There are a number of underground infiltration systems that can be installed to enhance groundwater recharge. The most common types include pre-cast concrete or plastic pits, chambers (manufactured pipes), perforated pipes, and galleys. i Ability to meet specific standards Advantages/Benefits: Standard Description • Provides groundwater recharge 2 - Peak Flow N/A • Reduces downstream flooding • Preserves the natural water balance of the site 3 - Recharge Provides groundwater recharge • Can remove other pollutants besides TSS 4 - TSS 80% • Can be installed on properties with limited Removal space • Useful in stormwater retrofit applications 5 - Higher May be used if 44%of TSS is Pollutant removed with a pretreatment BMP Disadvantages/Limitations: Loading prior to infiltration. Land uses with • Limited data on field performance the potential to generate runoff • Susceptible to clogging by sediment with high concentrations of oil and . Potential for mosquito breeding due to grease require an oil grit separator standing water if system fails or equivalent prior to discharge to the infiltration structure. Infiltration must be done in accordance with 314 CMR 5.00. 6 - Discharges Highly recommended near or to Critical Areas 7 - Suitable with pretreatment Redevelopment Pollutant Removal Efficiencies • Total Suspended Solids (TSS) 80% • Nutrients (Nitrogen,phosphorus) Insufficient data • Metals (copper,lead,zinc,cadmium) Insufficient data • Pathogens (coliform,e coli) Insufficient data Structural BMPs- Volume 2 Chapter page 103 Subsurface Structures Modular Underground Infiltration System There are different types of subsurface structures: Infiltration Pit: A pre-cast concrete ' or plastic barrel with uniform $°"' `"$ Compacted 6atkfil3 �t • *# perforations. The bottom of the pit rtrpatrnent # # should be closed with the lowest �atexUle =,, > row of perforations at least 6 inches OurRpw (for� Modular storage structure above the bottom, to serve as a detention system) lined with geotextile sump. Infiltration pits typically ��xrltratlo7l include an observation well. The Crushed.washed pits may be placed linearly, so that stone layer as the infiltrative surfaces in the first Elevation pit clog, the overflow moves to the second pit for exfiltration. Place an outlet near the top of the infiltration pit to accommodate emergency Underground Plastic Chamber System overflows. MassDEP provides recharge credit for storage below Plastic chamber with Compacted till the emergency outflow invert. To Opel t�attom make an infiltration pit, excavate the pit, wrap fabric around the barrel, place stone in the bottom of the pit, place the barrel in the pit, and then \4 backfill stone around the barrel. ] Take a boring or dig an observation trench at the site of each proposed ` . " "" -' - " "a pit. Crushed.washed scone Filter fahri€ Chambers: These are typically adapted from the CT State Stormwater Manual manufactured pipes containing Elevation open bottoms and sometimes perforations. The chambers are placed atop a Gallevs: Similar to infiltration pits. Some designs stone bed. Take the same number of borings or consist of concrete perforated rectangular vaults. observation pits as for infiltration trenches. Do not Others are modular systems usually placed under confuse these systems with underground detention parking lots. When the galley design consists of systems (UDS) that use similar chambers. UDS are a single rectangular perforated vault, conduct one designed to attenuate peak rates of runoff--not to boring or observation trench per galley. When the recharge groundwater. galleys consist of interlocking modular units, take the same number of borings or observation pits as Perforated Pines: In this system, pipes containing for infiltration trenches. Do not confuse these galleys perforations are placed in a leaching bed, similar to a with vaults storing water for purposes of underground Title 5 soil absorption system (SAS). The pipes dose detention, which do not contain perforations. the leaching bed.Take the same number of borings or observation pits as for infiltration trenches. Perforated Applicability pipes by themselves do not constitute a stormwater Subsurface structures are constructed to store recharge system and receive no credit pursuant to stormwater temporarily and let it percolate into the Stormwater Standard No. 3. Do not confuse recharge underlying soil. These structures are used for small systems that use perforated pipes with perforated drainage areas (typically less than 2 acres). They are pipes installed to lower the water table or divert feasible only where the soil is adequately permeable groundwater flows. and the maximum water table and/or bedrock Structural BMPs- Volume 2 1 Chapter page 104 elevation is sufficiently low. They can be used to purpose of the subsurface structure and the stormwater control the quantity as well as quality of stormwater management program being used. Subsurface runoff, if properly designed and constructed. The structures should infiltrate good quality runoff only. structures serve as storage chambers for captured Pretreatment prior to infiltration is essential. stormwater,while the soil matrix provides treatment. The composition, configuration and layout of subsurface structures varies considerably depending Without adequate pretreatment, subsurface on the manufacturer. Follow the design criteria structures are not suitable for stormwater runoff from specified by vendors or system manufacturers. land uses or activities with the potential for high Install subsurface structures in areas that are easily sediment or pollutant loads. Structural pretreatment accessible for routine and non-routine maintenance. BMPs for these systems include, but are not limited to, deep sump catch basins, proprietary separators, As with infiltration trenches and basins, install and oil/grit separators. They are suitable alternatives subsurface structures only in soils having suitable to traditional infiltration trenches and basins for infiltration capacities as determined through field space-limited sites. These systems can be installed testing. Determine the infiltrative capacity of the beneath parking lots and other developed areas underlying native soil through the soil evaluation provided the systems can be accessed for routine set forth in Volume 3. Never use a standard septic maintenance. system percolation test to determine soil permeability because this test tends to greatly overestimate the Subsurface systems are highly prone to clogging. infiltration capacity of soils. Pretreatment is always required unless the runoff is strictly from residential rooftops. Subsurface structures are typically designed to function off-line. Place a flow bypass structure Effectiveness upgradient of the infiltration structure to convey high Performance of subsurface systems varies by flows around the structure during large storms. manufacturer and system design.Although there are limited field performance data, pollutant removal Design the subsurface structure so that it drains efficiency is expected to be similar to those of within 72 hours after the storm event and completely infiltration trenches and basins (i.e., up to 80%of TSS dewaters between storms. Use a minimum draining removal). MassDEP awards a TSS removal credit of time of 6 hours to ensure adequate pollutant removal. 80%for systems designed in accordance with the Design all ports to be mosquito-proof, i.e., to inhibit specifications in this handbook. or reduce the number of mosquitoes able to breed within the BMP. Planning Considerations Subsurface structures are excellent groundwater The minimum acceptable field infiltration rate is 0.17 recharge alternatives where space is limited. inches per hour.Subsurface structures must be sized Because infiltration systems discharge runoff to in accordance with the procedures set forth in Volume groundwater, they are inappropriate for use in areas 3. Manufactured structures must also be sized in with potentially higher pollutant loads (such as gas accordance with the manufacturers' specifications. stations), unless adequate pretreatment is provided. Design the system to totally exfiltrate within 72 hours. In that event, oil grit separators, sand filters or equivalent BMPs must be used to remove sediment, Design the subsurface structure for live and dead floatables and grease prior to discharge to the loads appropriate for their location. Provide measures subsurface structure. to dissipate inlet flow velocities and prevent channeling of the stone media. Generally, design the Design system so that inflow velocities are less than 2 feet Unlike infiltration basins,widely accepted design per second (fps). standards and procedures for designing subsurface All of these devices must have an appropriate structures are not available. Generally, a subsurface number of observation wells, to monitor the water structure is designed to store a "capture volume" of surface elevation within the well, and to serve as a runoff for a specified period of"storage time." The sampling port. definition of capture volume differs depending on the Structural BMPs- Volume 2 1 Chapter page 105 Each of these different types of structures,with Adapted from: the exception of perforated pipes in leaching fields Connecticut Department of Environmental Conservation. similar to Title 5 systems, must have entry ports to Connecticut Stormwater Quality Manual.2004. MassHighway. Storm Water Handbook for Highways and allow worker access for maintenance, in accordance Bridges.May2004. with OSHA requirements. Construction Stabilize the site prior to installing the subsurface structure. Do not allow runoff from any disturbed areas on the site to flow to the structure. Rope off the area where the subsurface structures are to be placed. Accomplish any required excavation with equipment placed just outside of this area. If the size of the area intended for exfiltration is too large to accommodate this approach, use trucks with low- pressure tires to minimize compaction. Do not allow any other vehicles within the area to be excavated. Keep the area above and immediately surrounding the subsurface structure roped off to all construction vehicles until the final top surface is installed (either paving or landscaping). This prevents additional compaction. When installing the final top surface, work from the edges to minimize compaction of the underlying soils. Before installing the top surface, implement erosion and sediment controls to prevent sheet flow or wind blown sediment from entering the leach field. This includes, but is not limited to, minimizing land disturbances at any one time, placing stockpiles away from the area intended for infiltration, stabilizing any stockpiles through use of vegetation or tarps, and placing sediment fences around the perimeter of the infiltration field. Provide an access port, man-way, and observation well to enable inspection of water levels within the system. Make the observation well pipe visible at grade (i.e., not buried). Maintenance Because subsurface structures are installed underground, they are extremely difficult to maintain. Inspect inlets at least twice a year. Remove any debris that might clog the system. Include mosquito controls in the Operation and Maintenance Plan. Structural BMPs- Volume 2 Chapter page 106 III. APPENDIX F Stormwater Pollution Prevention Plan (SWPPP) (will be finalized and submitted before construction commences) III. APPENDIX G Operation and Maintenance Plan (O&M) with Long Term Pollution Prevention Plan (LTPPP) Operation and Maintenance Plan The Arsenal Project Arsenal Street Watertown, MA 02472 Prepared for: Boylston Properties 800 Boylston Street, Suite 1390 Boston, MA 02199 and The Wilder Companies 800 Boylston Street, Suite 1300 Boston, MA 02199 Prepared by: RJ O'CONNELL & ASSOCIATES, INC. 80 Montvale Ave, Suite 201 Stoneham, MA 02180 Date: July 11, 2016 TABLE OF CONTENTS Introduction Section 1 -Stormwater Management System— Operations and Maintenance Section 2 -Long Term Pollution Prevention Plan (LTPPP) A. Materials Covered B. Materials Management Practices C. Spill Prevention and Response Procedures Section 3 - Illicit Discharge Statement Section 4 - Snow Management and Disposal Plan Section 5 - Public Safety Features Appendices Appendix A - The Arsenal Project Maintenance and Inspection Forms Activity Guide Comprehensive Annual Evaluation and Inspection Report Annual Training Signoff Sheet Weekly Inspection Checklist Monthly Inspection Checklist Quarterly Inspection Checklist Semi-Annually Inspection Checklist Spill and Leak History CDS Inspection and Maintenance Guide Operations and Maintenance Plan INTRODUCTION This Operations and Maintenance Plan has been prepared to ensure that the stormwater management system implemented for The Arsenal Project to functions as designed and to develop and carry out suitable practices for source control and pollution prevention. It consists of six sections: Section 1 - Stormwater Management System-Operations and Maintenance, which describes the various components of the stormwater management system, identifies the inspection and maintenance tasks to be undertaken after construction is complete and a schedule for implementing these tasks to insure the proper, long-term operation of the system. Section 2 - Long Term Pollution Prevention Plan which identifies and implements suitable measures, practices and procedures for source control and pollution prevention. Section 3- Illicit Discharge Statement. Section 4- Snow Management and Disposal Plan which describes how snow removal will be managed and deicing operations performed. Section 5- Public Safety Features which lists features of the stormwater management system to insure the safety of the public. 1 SECTION 1 —STORMWATER MANAGEMENT SYSTEM- OPERATION AND MAINTENANCE The objectives of the stormwater management system are to effectively control and treat stormwater runoff from the site in accordance with the Massachusetts Stormwater Management Standards. To accomplish this objective, the following Best Management Practices (BMP's) are included in the proposed office building's stormwater management system: Pre-treatment BMP's • Sweeping of paved surface areas to remove solids and reduce suspended solids in surface runoff. • Maintaining catch basins to reduce the discharge of sediment and pollutants. • Maintaining oil/particle separators for removal of Total Suspended Solids (TSS), oil and grease. Treatment BMP's • Maintaining the subsurface infiltration systems to recharge groundwater, reduce peak rates of runoff from the site and remove suspended solids from stormwater runoff through infiltration into the ground. To ensure the ongoing and proper functioning of the on-site stormwater management/BMP facilities, this Operations and Maintenance Plan has been developed. In consideration of the foregoing, it is the ongoing responsibility of the Landowner, his successors and assignees to adequately maintain the on-site stormwater management/BMP facilities. Adequate maintenance is herein defined as good working condition so that these facilities are performing their design functions. Based on this, the Landowner, his successors and assignees are required to create a Pollution Prevention Team (PPT)that will be responsible for implementing the Operations and Maintenance Plan. Upon transfer of ownership of the property, the Landowner is required to notify the new owner of the presence of the stormwater management system and the requirements of this Operations and Maintenance Plan. Propertv Information Address: 485 Arsenal Street Watertown, MA 02472 2 Landowner and Pollution Prevention Team Leader Owner's Name: Boylston Properties and The Wilder Companies Team Leader: TBD Title: Owner Office Phone: TBD Email: TBD Responsibilities: Coordinate all aspects of the Operations and Maintenance Plan, coordinate and hire the other Pollution Prevention team members in order to conduct inspections, keep all records, coordinate with contractors for maintenance and repairs of the stormwater management system. Spill Prevention & Control Contractor The following contacts shall be notified only in those instances identified within MA DEP-310 CMR 40-subpart C. Primary Contact: TBD Office Phone: TBD Emergency Contact: Company Name: TBD Contact Name: TBD Emergency Phone: TBD Consultant Contact: Company Name: TBD Contact Name: TBD Phone: TBD Department of Environmental Protection (DEP) Contact Spill Emergency Coordinator Contact Name: TBD Phone: TBD Municipal Contacts Contact Name: Town of Watertown, Department of Public Works, Gerald S. Mee, Jr., Superintendent Phone: 781-972-6420 Other Pollution Prevention Team Members Member: Qualified Engineering and/or Environmental Consulting Firm(s) Responsibilities: Conduct scheduled inspections, maintain records, advise the Team Leader of maintenance needs, ensure inspection maintenance and repairs are completed, keep and maintain all records and inspection reports. 3 Company Name(s): TBD Address: Office Phone: Team Member Training The Pollution Prevention Team Leader will coordinate an annual in-house training session with the qualified Engineering and/or Environmental Consulting Firm to discuss the Operations and Maintenance Plan, ongoing inspection and maintenance and preventative maintenance procedures. Annual training session will generally include the following: • Discuss the Operations and Maintenance Plan o What it is- identify potential sources of stormwater pollution and methods of reducing or eliminating that pollution o What it contains- emphasize good housekeeping measures and location of potential pollution sources. o Pollution Prevention Team- introduce the team and responsibilities, explain that the objective is to continually monitor the stormwater management system and encourage input and assistance from all. • Review and explain the storm drainage system, how it works and its components, note the receiving resource area in which the storm drainage system discharges into and the role each one of these areas play. • Emphasize the importance of maintaining current and up-to-date inspection reports and maintenance records of BMP's. Documentation shall include any changes to the O&M Plan's procedures to accommodate changes and revisions to BMP's. The components of the stormwater management system must be inspected, monitored and maintained in accordance with the following in order to ensure that the on-site stormwater management/BMP facilities for The Arsenal Project are functioning as designed. Routine inspection and proper maintenance of these individual components is essential to providing the long-term enhancement of both the quality and quantity of the runoff from the property. Catch Basins: Stormwater runoff from pavement areas is directed to catch basins via curbing and site grading. To ensure proper functioning of catch basins, each on-site catch basin will be inspected and maintained as follows: Inspection: Quarterly and after major storm events (3.2 inches or more in a 24 hour period). Structural damage and other malfunctions to be noted and reported. 4 Maintenance: Cleaned four times a year or when the sump is half full by a licensed contractor. Sediment and hydrocarbons will be properly handled and legally disposed of off site in accordance with local, state, and federal guidelines and regulations. Any structural damage to catch basins and/or castings will be repaired upon discovery. Sweeping and Site Clean-Uv Routine sweeping of paved areas is an effective method to provide important nonpoint source pollution control and will be performed by mechanical sweepers. Most stormwater pollutants travel with the suspended solids contained in the stormwater runoff and regular sweeping will help reduce a portion of this load. Sweeping, especially during the period immediately following winter snowmelt (March/April) when road sand and other debris has accumulated on the pavement,will capture a peak sediment load before spring rains wash residual sand from winter applications into nearby resource areas. Inspection: Paved areas will be inspected for litter on a weekly basis and picked up and disposed of immediately. Maintenance: All parking areas, sidewalks, driveways and other impervious surfaces (except roofs)will be swept clean of sand, litter, trash, etc. on a monthly basis. A log of land/lot sweeping and cleanup will be kept. Housekeeping concerns noted by store leadership, PPT members, guests and others will be noted and acted upon. Separate cleanup services will be conducted at least twice a year, once between November 14 and December 15 (after leaf fall) and once during the month of April (after snow melt). Additional cleanup services will be conducted as necessary. CDS Oil/Particle Separators The Continuous Deflective Separator(CDS) unit separates and traps debris, sediment and oil and grease from stormwater runoff. The indirect screening capability of the system allows for 100%removal of floatables and neutrally buoyant material. There are seven CDS units on site designed to treat stormwater runoff prior to discharging into the subsurface infiltration systems. Inspection: Quarterly Maintenance: Jet/vacuumed by a licensed contractor at least twice per year. Accumulated sediment and hydrocarbons will be disposed of in accordance with applicable local, state and federal guidelines and regulations. 5 Subsurface Infiltration Svstems Subsurface infiltration systems are located along the south side of the site, adjacent to Greenough Boulevard and beneath the parking lot next to Building El. The systems consist of either 5 or 10 ft. diameter, perforated, corrugated metal pipes surrounded in crushed stone. The systems are designed to temporarily retain storm runoff and infiltrate it into the underlying soil. Inspection: Inlets to be inspected twice a year. Maintenance: Clean when there is a build-up of visible sediment at the inlet. Sediment to be removed by jet vacuum and disposed of legally in accordance with local, state and federal guidelines and regulations. Please refer to Appendix A for the Inspection Forms,which are to be used by the Pollution Prevention Team member responsible for conducting the scheduled inspections. 6 SECTION 2 —LONG TERM POLLUTION PREVENTION PLAN (LTPPP) A. MATERIALS COVERED The following materials or substances are expected to be present onsite after construction: Cleaning solvents Petroleum based products Detergents Pesticides/Insecticides Paints/Solvents Fertilizers/Herbicides Acids Pet waste Solid Waste Contaminated Soil B. MATERIALS MANAGEMENT PRACTICES The following are the material management practices that will be used to reduce the risk of spills or other accidental exposure of materials and substances to stormwater runoff. The Pollution Prevention Team Leader will be responsible for ensuring that these procedures are followed: 1. Good Housekeeping The following good housekeeping practices will be followed onsite after construction: a) An effort will be made to store only enough products required to do the job. b) All materials stored onsite will be stored in a neat, orderly manner and, if possible, under a roof or in a containment area. At a minimum, all containers will be stored with their lids on when not in use. Drip pans shall be provided under all dispensers. c) Products will be kept in their original containers with the original manufacturer's label in legible condition. d) Substances will not be mixed with one another unless recommended by the manufacturer. e) Whenever possible, all of a product will be used up before disposing of the container. f) Manufacturer's recommendations for proper use and disposal will be followed. g) A Pollution Prevention Team Member will be responsible for daily inspections to ensure proper use and disposal of materials. 2. Hazardous Substances These practices will be used to reduce the risks associated with Hazardous Substances. Material Safety Data Sheets (MSDS's) for each product with 7 hazardous properties that is used at the Project will be obtained and used for the proper management of potential wastes that may result from these products. An MSDS will be posted in the immediate area where such product is stored and/or used and another copy of each MSDS will be maintained on-site, in the management office. Each employee who must handle a Hazardous Substance will be instructed on the use of MSDS sheets and the specific information in the applicable MSDS for the product he/she is using, particularly regarding spill control techniques. a) Products will be kept in original containers with the original labels in legible condition. b) Original labels and MSDS's will be procured and used for each product. c) If surplus product must be disposed of, the manufacturer's and local/state/federal required methods for proper disposal must be followed. 3. Hazardous Waste It is imperative that all Hazardous Waste be properly identified and handled in accordance with all applicable Hazardous Waste Standards, including the storage, transport and disposal of the Hazardous Wastes. There are significant penalties for the improper handling of Hazardous Wastes. It is important that the Pollution Prevention Team Leader seeks appropriate assistance in making the determination of whether a substance or material is a Hazardous Waste. For example, Hazardous Waste may include certain Hazardous Substances, as well as pesticides, paints,paint solvents, cleaning solvents, contaminated soils, and other materials, substances or chemicals that have been discarded(or are to be discarded) as being out-of-date, contaminated, or otherwise unusable. The Pollution Prevention Team Leader is responsible for ensuring that all Pollution Prevention Team Members are instructed as to these Hazardous Waste requirements and also that the requirements for handling and disposal are being followed. 4. Product Specific Practices The following product specific practices will be followed on the job site: a) Petroleum Products Petroleum products will be stored in tightly sealed containers which are clearly labeled. Petroleum storage tanks shall be located a minimum of 100 linear feet from wetland resource areas, drainage ways, inlets and surface waters unless stored within a building. Any petroleum storage tanks stored onsite will be located within a containment area that is designed with an impervious surface between the tank and the ground. The secondary containment must be designed to provide a containment volume that is equal to 110% of the volume of the largest tank. Drip pans shall be provided for 8 all dispensers. Any asphalt substances used onsite will be applied according to the manufacturer's recommendations. The location of any fuel tanks and/or equipment storage areas must be identified on the Erosion Control Plan by the Contractor once the locations have been determined. b) Fertilizers, Herbicides, Pesticides, and Insecticides Fertilizers, herbicides, pesticides, insecticides and/or pool chemicals will be applied only in the minimum amounts recommended by the manufacturer. Once applied, they will be worked so as to limit exposure to storm water. Storage will be in a covered shed. The contents of any partially used bags or containers will be transferred to a sealable plastic bin to avoid spills. c) Paints, Paint Solvents, and Cleaning Solvents All containers will be tightly sealed and stored when not in use. Excess paint and solvents will not be discharged to the storm sewer system but will be properly disposed of according to manufacturer's instructions or state and federal regulations. 5. Solid Waste All waste materials will be collected and stored in an appropriately covered container and/or securely contained metal dumpster rented from a local waste management company which must be a licensed solid waste management company. The dumpster will comply with all local and state solid waste management regulations. All trash and debris from the site will be deposited in dumpsters. The dumpsters will be emptied a minimum of once per week or more often if necessary. All personnel will be instructed regarding the correct procedures for waste disposal. All waste dumpsters and roll-off containers will be located in an area where the likelihood of the containers contributing to storm water discharges is negligible. No debris, refuse or other materials, including but not limited to landscaping debris, leaves, shrubs and tree trimmings, logs, bricks stone or trash shall be deposited within the vegetated wetland or within 100 feet of the vegetated wetland. 6. Contaminated Soils Any contaminated soils (resulting from spills of Hazardous Substances or Oil) will be contained and cleaned up immediately in accordance with the procedures given in the Materials Management Plan and in accordance with applicable state and federal regulations. If there is a release, it should be reported as a spill, if it otherwise meets the requirements for a reportable spill. 9 7. Pet Waste The site will be inspected weekly for pet waste. Pet waste will be collected, placed in a closed, tied trash bag and disposed of in accordance with applicable code requirements. C. SPILL PREVENTION AND RESPONSE PROCEDURES The Pollution Prevention Team Leader will train all personnel in the proper handling and cleanup of spilled Hazardous Substances or Oil. No spilled Hazardous Substances or Oil will be allowed to come in contact with storm water discharges. If such contact occurs, the storm water discharge will be contained on site until appropriate measures in compliance with state and federal regulations are taken to dispose of such contaminated storm water. It shall be the responsibility of the Pollution Prevention Team Leader to be properly trained, and to train all personnel in spill prevention and clean up procedures. 1. In order to prevent or minimize the potential for a spill of Hazardous Substances or Oil to come into contact with storm water, the following steps will be implemented: a) All Hazardous Substances or Oil (such as pesticides,petroleum products, fertilizers, detergents, acids,paints,paint solvents, cleaning solvents, etc.)will be stored in a secure location,with their lids on,preferably under cover, when not in use. b) The minimum practical quantity of all such materials will be kept on site. c) A spill control and containment kit (containing, for example, absorbent materials, acid neutralizing powder,brooms, dust pans, mops, rags, gloves, goggles,plastic and metal trash containers, etc.)will be provided on site. d) Manufacturer's recommended methods for spill cleanup will be clearly posted and site personnel will be trained regarding these procedures and the location of the information and cleanup supplies. e) It is the Pollution Prevention Team Leader's responsibility to ensure that all Hazardous Waste on site is disposed of properly by a licensed hazardous material disposal company. The Pollution Prevention Team Leader is responsible for not exceeding Hazardous Waste storage requirements mandated by the EPA or state and local authority. 2. In the event of a spill of Hazardous Substances or Oil, the following procedures must be followed: a) All measures must be taken to contain and abate the spill and to prevent the discharge of the Hazardous Substance or Oil to storm water or off-site. (The spill area must be kept well ventilated and personnel must wear appropriate protective clothing to prevent injury from contact with the Hazardous Substances.) 10 b) For spills of less than five (5) gallons of material, proceed with source control and containment, clean-up with absorbent materials or other applicable means unless an imminent hazard or other circumstances dictate that the spill should be treated by a professional emergency response contractor. c) For spills greater than five (5) gallons of material immediately contact the MA DEP Hazardous Waste Incident Response Group at (617) 792-7653 and an approved emergency response contractor. Provide information on the type of material spilled, the location of the spill, the quantity spilled, and the time of the spill to the emergency response contractor or coordinator, and proceed with prevention, containment and/or clean-up if so desired. d) If there is a Reportable Quantity(RQ) release, then the National Response Center will be notified immediately at (800) 424-8802; within 14 days a report will be submitted to the EPA regional office describing the release, the date and circumstances of the release and the steps taken to prevent another release. This Pollution Prevention Plan must be updated to reflect any such steps or actions taken and measures to prevent the same from reoccurring. 3. The Pollution Prevention Team Leader will be the spill prevention and response coordinator. He/she will designate the individuals who will receive spill prevention and response training. These individuals will each become responsible for a particular phase of prevention and response. The names of these personnel will be posted in the material storage area and in the management office. 11 SECTION 3 -ILLICIT DISCHARGE STATEMENT Certain types of discharges are allowable under the U.S. Environmental Protection Agency Construction General Permit, and it is the intent of this LTPPP to allow such discharges. These types of discharges will be allowed under the conditions that no pollutants will be allowed to come in contact with the water prior to or after its discharge. The control measures which have been outlined previously in this LTPPP will be strictly followed to ensure that no contamination of these non-storm water discharges takes place. Illicit discharges, if they exist currently, will be contained and eliminated in the manner specified by local, state and federal regulations, and will be prohibited in the proposed development. Jeff Heidelberg for Boylston Properties 12 SECTION 4 - SNOW MANAGEMENT AND DISPOSAL PLAN Snow management will be overseen by a full-time Property Manager who will implement this plan and be authorized to utilize additional resources should unusual events occur. The Snow Management Contractor (SMC) shall be responsible for maintaining all roads, driveways,parking lots, sidewalks and pedestrian access areas for clear and safe travel. The SMC shall report directly to the Property Manager and maintain communication via cell phones 24 hours per day, 7 days per week. All roads, drives, entrances and exits are the first priority. During extreme events, the first priority will be to clear and maintain proper access for residents and public safety vehicles. The next priority is parking areas, sidewalks, fire hydrants, and delivery areas. Snow will not be piled around light bases and handicap parking areas shall be cleared frequently. The anti-icing operations typically precede snow plowing and will be provided when conditions warrant. Within 12 months of concrete walks,pads, or other features being poured, no salt shall be placed on those surfaces. After the materials have cured for 12 months, a combination of salt (Halite or Rock Salt) and sand("washed", fine to medium grade) shall be utilized. Parking areas shall receive spot treatment only when and where needed in a similar manner. Snow plowing shall commence upon accumulation of two inches ("2") or more. Snow shall be deposited in designated areas. The SMC shall keep existing catch basins open for drainage or water resulting from melting. Once the storm is over, the SMC shall monitor all areas on-site for icy spots and snowdrifts. If needed, an application of sand and salt will be applied to all streets and roads so that the riding surface remains drivable. When the ambient temperature drops below 25 degrees F, all major areas will receive an application of pre-wetted salt with calcium chloride to maintain melting action and an ice-free surface for as long as possible. Salt loses its effectiveness at temperatures drop below 25 degrees F. Deicing chemicals will be kept in original containers with the original product label in legible condition. When not in use, deicing materials will be stored in a neat, orderly manner under cover with their container lids on. 13 SECTION 5 -PUBLIC SAFETY FEATURES The following measures have been incorporated into the stormwater management system to insure the safety of the public: • Storm drain manholes and catch basins provided with heavy duty covers and/or grates and designed to withstand H2O loading. • Control and collection of stormwater runoff through positive drainage and curbing directing it toward drainage inlet structures. • Treatment of stormwater runoff from paved surfaces to remove 80% of the average annual post-construction load of Total Suspended Solids (TSS). • Reduction in peak rates of runoff and volume from the site under post- redevelopment conditions as compared to pre-developed conditions. • Development and implementation of an Operations and Maintenance Plan to insure the proper functioning of the stormwater management system and a Long Term Pollution Prevention Plan identifying potential pollution sources and suitable practices to control and prevent them from impacting the environment and/or the public's health and safety. 14 Appendix A The Arsenal Project Maintenance and Inspection Forms 15 The Arsenal Project Operation and Maintenance Plan Activity Guide The table below is a list of the minimum inspection and maintenance activities the Pollution Prevention Team needs to conduct for the Stormwater Operations and Management Plan and who is responsible for the activity. The Activity Guide is provided to assist the Pollution Prevention Team Leader and ensure that the activities are being conducted as scheduled. Timing Activity Responsible Party Weekly Inspect lot/land PPT Pet waste management PPT Parking lot sweeping PPT Contractor Quarterly Inspect and clean catch basins PPT/Contractor Inspect CDS oil/particle separators PPT/Contractor Semi-Annually Clean CDS Oil/Particle Separators PPT/Contractor Inspect subsurface infiltration systems PPT/Contractor Annually Pollution Prevention Team training PPT Leader Comprehensive annual stormwater evaluation and PPT Leader inspection report April Spring clean-up, PPT/Contractor Between Fall clean-up PPT/Contractor November 14 and December 15 The Arsenal Project Operations and Maintenance Plan Comprehensive Annual Evaluation and Inspection Report Once a year, the Pollution Prevention Team Leader must inspect and evaluate all aspects and provisions of the Opeations and Maintenance Plan, complete the following report and keep a copy on file at the site. Inspector/Reviewers: Date of Inspection/Review: Note any changes to the Plan in the space below and in the appropriate section of the Plan. 1. Review the Pollution Prevention Team list and update if necessary. Does the Pollution Prevention Team list need updating: (circle one) Yes No 2. Review the Operations and Maintenance Plan (O&M Plan). Are there sections of the O&M Plan that need updating? (circle one) Yes No 3. Review Monthly and Weekly Checklists. Update these as necessary -Are there any updates needed to Spill and Leak History and/or the checklists? (circle one) Yes No 4. Review site drawings and update if necessary Are there updates needed to any of the drawings? (circle one) Yes No Requested Changes (attach revisions) The Arsenal Project Operations and Maintenance Plan Annual Training Signoff Sheet For each Operations and Maintenance Plan training session, the Team Leader should keep records of all attending Team Members using the signoff sheet below, as well as the training agenda, notes, etc. Training Date: Topic: Trainer: Team Member Name Team Member Signature The Arsenal Project Operations and Maintenance Plan Weekly Inspection Checklist The site will be checked each week for trash and debris by a member of the Pollution Prevention Team. If any trash or debris is observed in the specified area, write "yes" in the 2nd column and note the problem and corrective measures taken in the appropriate space. Make a new copy of this checklist each week. Date: Checklist completed by: GROUNDS AREA TO TRASH OR DEBRIS PRESENT? DESCRIPTION OF CORRECTIVE MEASURES CHECK PROBLEM TAKEN Parking Lot & Roadways Landscaped Areas Compactor/Dumpster& Loading Dock Areas Perimeter of Property The Arsenal Project Operations and Maintenance Plan Monthly Inspection Checklist The following will be checked each month for sources of pollutants by a member of the Pollution Prevention Team. If the condition in the "check for" column is observed,note the problem and corrective measures taken in the appropriate space. Make a new copy of the checklist each month. Date: Checklist completed by: LOCATION CHECK FOR... DESCRIPTION OF CORRECTIVE MEASURES PROBLEM(IF PRESENT) TAKEN Loading Dock Areas Evidence of Spills or Leaks, Spill Response equipment, Trash Parking Lot and Paved Spillage and Trash Areas Perimeter of Site Trash Outside Storage Areas Spillage (grease, etc.) The Arsenal Project Operations and Maintenance Plan Quarterly Inspection Checklist The following will be checked each quarter for sources of pollutants by a member of the Pollution Prevention Team. If the condition in the "check for" column is observed,note the problem and corrective measures taken in the appropriate space. Make a new copy of the checklist each month. Date: Checklist completed by: BMP CHECK FOR... DESCRIPTION OF CORRECTIVE MEASURES PROBLEM(IF PRESENT) TAKEN Catch Basins Trash, oil sheen, hood(securely fastened) excessive sediment CDS Oil/Particle Trash, excessive sediment Separator The Arsenal Project Operations and Maintenance Plan Semi-Annually Inspection Checklist The following will be checked each quarter for sources of pollutants by a member of the Pollution Prevention Team. If the condition in the "check for" column is observed, note the problem and corrective measures taken in the appropriate space. Make a new copy of the checklist each month. Date: Checklist completed by: BMP CLEAN AND REMOVE... DESCRIPTION OF CORRECTIVE MEASURES PROBLEM(IF PRESENT) TAKEN Subsurface Infiltration Trash, excessive sediment at inlets System CDS Oil/Particle Trash, excessive sediment Separator The Arsenal Project Operations and Maintenance Plan Annual Inspection Checklist The following will be checked each quarter for sources of pollutants by a member of the Pollution Prevention Team. If the condition in the "check for" column is observed,note the problem and corrective measures taken in the appropriate space. Make a new copy of the checklist each month. Date: Checklist completed by: BMP CLEAN AND REMOVE... DESCRIPTION OF CORRECTIVE MEASURES PROBLEM(IF PRESENT) TAKEN Pollution Prevention Prepare annual stormwater evaluation Team Training and inspection report The Arsenal Project Long Term Pollution Prevention Plan Spill and Leak History to Date Spill Leak Location Description Response Measures to Reporting Procedures Prevent Pollution Reoccurrence Prevention Team Member (MM/DD/YY) (check one) (as indicated on Type of Quantity Source, if Reason Site Map) Material known CONSTRUCTION PRODUCTS INC. CDS° Inspection and Maintenance Guide AAA 71 77 Frei `a U.ruff[�H lk {� !M1 � •i IF IIIIIIIII11`\\\\ lips TECHNOLOGIES Maintenance Cleaning The CDS system should be inspected at regular intervals and Cleaning of a CDS systems should be done during dry weather maintained when necessary to ensure optimum performance. conditions when no flow is entering the system.The use of a The rate at which the system collects pollutants will depend more vacuum truck is generally the most effective and convenient heavily on site activities than the size of the unit. For example, method of removing pollutants from the system. Simply remove unstable soils or heavy winter sanding will cause the grit chamber the manhole covers and insert the vacuum hose into the sump. to fill more quickly but regular sweeping of paved surfaces will The system should be completely drained down and the sump slow accumulation. fully evacuated of sediment.The area outside the screen should also be cleaned out if pollutant build-up exists in this area. Inspection In installations where the risk of petroleum spills is small, liquid Inspection is the key to effective maintenance and is easily contaminants may not accumulate as quickly as sediment. performed. Pollutant transport and deposition may vary from However,the system should be cleaned out immediately in year to year and regular inspections will help ensure that the the event of an oil or gasoline spill should be cleaned out system is cleaned out at the appropriate time. At a minimum, immediately. Motor oil and other hydrocarbons that accumulate inspections should be performed twice per year(e.g. spring on a more routine basis should be removed when an appreciable and fall) however more frequent inspections may be necessary layer has been captured.To remove these pollutants, it may in climates where winter sanding operations may lead to rapid be preferable to use absorbent pads since they are usually less accumulations, or in equipment washdown areas. Installations expensive to dispose than the oil/water emulsion that may be should also be inspected more frequently where excessive created by vacuuming the oily layer.Trash and debris can be amounts of trash are expected. netted out to separate it from the other pollutants. The screen The visual inspection should ascertain that the system should be power washed to ensure it is free of trash and debris. components are in working order and that there are no Manhole covers should be securely seated following cleaning blockages or obstructions in the inlet and separation screen. activities to prevent leakage of runoff into the system from above The inspection should also quantify the accumulation of and also to ensure that proper safety precautions have been hydrocarbons,trash, and sediment in the system. Measuring followed. Confined space entry procedures need to be followed pollutant accumulation can be done with a calibrated dipstick, if physical access is required. Disposal of all material removed tape measure or other measuring instrument. If absorbent from the CDS system should be done in accordance with local material is used for enhanced removal of hydrocarbons,the level regulations. In many jurisdictions, disposal of the sediments may of discoloration of the sorbent material should also be identified be handled in the same manner as the disposal of sediments during inspection. It is useful and often required as part of an removed from catch basins or deep sump manholes. operating permit to keep a record of each inspection. A simple form for doing so is provided. Access to the CDS unit is typically achieved through two manhole access covers. One opening allows for inspection and cleanout of the separation chamber(cylinder and screen)and isolated sump. The other allows for inspection and cleanout of sediment captured and retained outside the screen. For deep units, a single manhole access point would allows both sump cleanout and access outside the screen. The CDS system should be cleaned when the level of sediment has reached 75%of capacity in the isolated sump or when an appreciable level of hydrocarbons and trash has accumulated. If absorbent material is used, it should be replaced when significant discoloration has occurred. Performance will not be impacted until 100%of the sump capacity is exceeded however it is recommended that the system be cleaned prior to that for easier removal of sediment. The level of sediment is easily ] determined by measuring from finished grade down to the top of the sediment pile. To avoid underestimating the level of sediment in the chamber,the measuring device must be lowered - to the top of the sediment pile carefully. Particles at the top of the pile typically offer less resistance to the end of the rod than s P� YP Y consolidated particles toward the bottom of the pile. Once this !r-•:._._� - --'� measurement is recorded, it should be compared to the as-built drawing for the unit to determine weather the height of the ;4 sediment pile off the bottom of the sump floor exceeds 75%of the total height of isolated sump. `* CDS Diameter Distance from Water Surface Sediment Model to Top of Sediment Pile Storage Capacity ft m ft m yd3 m3 ■ f • J Y .•• Y�'+f • ZTi.t-�f` !1���. 'ir1`_C N �. -1.]I.Yk',:,, ry� y„�_ ^ _���:�� .. �.`�.�y-fly"��P` -��•,��� �L= .1Jr�'�3� - •c. !S i "{• � :.� 'ti n.2".).:is 'a• -NEf' �.• Sa'1::- ' -. T•_ �41 ram; "•i'e•:i�- � [ - F — - 01— _- - ' '`� , IF _.t.��_ Support • Drawings and specifications are available at wvvw.contechstormwater.com. • Site-specific design support is available from our engineers. ©2010 CONTECH Stormwater Solutions CONTECH Construction Products Inc.provides site solutions for the civil engineering industry. CONTECH's portfolio includes bridges,drainage,sanitary sewer,stormwater and earth stabilization products.For information on other CONTECH division offerings,visit contech- cpi.com or call 800.338.1122 Nothing in this catalog should be construed as an expressed warranty or an implied warranty of merchantability or fitness for any particular purpose.See the CONTECH standard quotation or acknowledgement for applicable warranties and other terms and conditions of sale. The product(s)described may be protected by one or more of the following US patents: 5,322,629;5,624,576;5,707,527;5,759,415;5,788,848;5,985,157;6,027,639;6,350,374; 6,406.218;6,641,720;6,511,595;6,649,048;6,991,114;6,998,038;7,186,058;7,296,692; 7,297,266;7,517,450 related foreign patents or other patents pending. :rr •r • r r CDS Inspection • • CDS Model: Location: Water Floatable Describe Date depth to Layer Maintenance Maintenance Comments sediment' Thickness' Performed Personnel 1, The water depth to sediment is determined by taking two measurements with a stadia rod:one measurement from the manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. If the difference between these measurements is less than eighteen inches the system should be cleaned out, Note:To avoid underestimating the volume of sediment in the chamber,the measuring device must be carefully lowered to the top of the sediment pile. For optimum performance,the system should be cleaned out when the floating hydrocarbon layer accumulates to an appreciable thickness. In the event of an oil spill,the system should be cleaned immediately.