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HomeMy Public PortalAbout2013.12.10_Stormwater-Report_sm_201312271155331729Stormwater Report 58 Irving Street & 202-204 Arsenal Street Watertown, Massachusetts Submitted to: Town of Watertown December 10, 2013 Table of Contents 1.0 Introduction 1 1.1 Existing Conditions 1 1.2 Proposed Conditions 1 1.3 Ground Cover 2 2.0 Stormwater Management 2 2.1 Method of Calculations 2 2.2 Sources of Data 3 2.3 Rainfall Depths 3 2.4 Soil Conditions 3 2.5 Existing Stormwater Management 3 2.5.1 Existing Drainage System 3 2.5.2 Watershed 4 2.5.3 Existing Runoff Calculations 4 2.6 Proposed Stormwater Management 4 2.6.1 Proposed Drainage System 4 2.6.2 Proposed Watershed 5 2.6.3 Proposed Runoff Calculations 6 2.6.4 Storm Drainage Pipe System 6 3.0 DEP Stormwater Standards 7 3.1 Standard No. 1 — Untreated Stormwater 7 3.2 Standard No. 2 — Post -development Peak Discharge Rates 7 3.3 Standard No. 3 - Recharge to Groundwater 8 Standard No. 4 - TSS Removal 8 3.3.1 Street Sweeping 8 3.3.2 Deep Sump/Hooded Catch Basins 8 3.3.3 Rain Gardens 9 3.3.4 Stormceptor® Treatment Units 9 3.3.5 StormTech® Infiltration Basin 9 3.4 Standard No. 5 - Higher Potential Pollutant Loads 9 3.5 Standard No. 6 - Protection of Critical Areas 10 3.6 Standard No. 7 - Redevelopment Projects 10 3.7 Standard No. 8 - Erosion/Sediment Control 10 3.8 Standard No. 9 - Operation/Maintenance Plan 11 Tetra Tech 3.9 Standard No. 10 - Illicit Discharge 11 4.0 Conclusion 11 Tetra Tech List of Tables Table 1 Ground Cover - Hydrologic Area 2 Table 2 Rainfall Depths 3 Table 3 Existing Peak Runoff Rates 4 Table 4 Proposed Peak Runoff Rates 6 Table 5 Comparison of Peak Runoff Rates 8 List of Figures Figure 1 Figure 2 Figure 3 Figure 4 USGS Locus Map Existing Watershed Map Proposed Watershed Map Proposed Catch Basin Catchment Areas List of Appendices Appendix A Appendix B Appendix C Appendix D Appendix E Appendix F Appendix G Stormwater Checklist HydroCAD® Report Groundwater Recharge Calculations Water Quality Calculations StormCAD Report Operations and Maintenance Plan Supporting Documentation Tetra Tech 1.0 Introduction This Stormwater Management Report, prepared in accordance with Massachusetts Department of Environmental Protection (DEP) Stormwater Standards, is submitted on behalf of the applicants, Hanover R.S. Limited Partnership and Cressent W/S Venture LLC. The report summarizes the drainage analysis and Stormwater Management Plan for the proposed "58 Irving Street and 202-204 Arsenal Street Redevelopment Project" located in Watertown, Massachusetts. See Figure 1, USGS Locus Map. The purpose of the Stormwater Management Plan is to provide a comprehensive framework for the long-term protection of natural resources and the downstream drainage infrastructure from degradation as a result of stormwater discharges. This is achieved through the use of a variety of water quality and quantity control measures designed to decrease the amount of pollutants discharged from the Site and significantly reduce discharge rates and volumes. Although the project will result in a net increase in open space of over one acre, stormwater management facilities have been designed to further reduce stormwater discharges. Significant reductions in peak stormwater discharge rates have been achieved for the 2, 10, 25 and 100 year storm events. In the more frequent 2 year storm event stormwater discharges have been nearly eliminated. 1.1 Existing Conditions The project site (the "Property") consists of three parcels totaling 7.21 acres, located at 58 Irving Street, 202-204 Arsenal Street and 204 Rear Arsenal Street. The project site is bounded by residential neighborhoods and streets to the north, commercial and office buildings to both the east and west, and commercial buildings and Arsenal Street to the south. The Property contains a vacant industrial -type single -story building of approximately 130,000 square feet, as well as a vacant 2,700 square foot two-story commercial store -type building located on Arsenal Street. The majority of the Property consists of impervious areas, either as buildings or paved parking areas and driveways. The primary site access is from Arsenal Street, along the south side of the Property, and located immediately east of the small building on the Property. A secondary access, currently gated and locked, is from north of the Property and is an extension of the dead-end residential street known as Birch Road. There is four (4) foot stone box culvert located on the Property which flows west to east under 58 Irving Street which will be relocated around the proposed four-story mixed use building. The site slopes steeply downward from Arsenal Street in a northerly direction into the site by approximately 8 to 13 feet. The elevation along the Arsenal Street frontage is between 38 feet and 43 feet. 1.2 Proposed Conditions Under the proposed conditions the property will be subdivided into two parcels. The Hanover parcel is a 274,135 square foot lot and consists of a single four-story mixed use building of 300 apartment units and approximately 6,200 square feet of retail space. The building has a below grade parking garage which has 519 parking spaces. The Cressent W/S Venture LLC parcel is a 39,929 square foot lot and consists of 30,637 square foot retail building and 111 parking spaces. The proposed project also includes two easements located west of the Cressent W/S Venture Tetra Tech 1 LLC parcel. The easements consist of a 12,530 square feet access easement and a 15,830 square feet parking easement. 1.3 Ground Cover The overall hydrologic study area for the proposed redevelopment is 8.0 acres. Table 1, below, summarizes the ground cover distribution for the hydrologic study area for existing and proposed conditions. There is a decrease of approximately 1.02 acres (44,431 square -feet) in impervious area with the proposed redevelopment. Table 1 Ground Cover - Hydrologic Area Area Existing (ac) Proposed (ac) Pavement 3.07 3.42 Roof 4.17 2.80 Grass 0.76 1.78 Total 8.0 8.0 2.0 Stormwater Management 2.1 Method of Calculations The hydrologic model created to analyze the hydrology of the site was developed using the Soil Conservation Service (SCS) Technical Release No. 20 (SCS unit hydrograph procedures) and SCS Technical Release No. 55 (for Times of Concentration and Runoff Curve Numbers). The stormwater facilities were modeled using the Simultaneous Routing Method. The hydrologic model was created and calculated with HydroCAD, Version 10.0 software, developed by Applied Microcomputer Systems. The runoff from the sub -drainage areas (HydroCAD subcatchments) is calculated based on rainfall and the watershed characteristics, and a runoff hydrograph (a runoff rate versus time curve) is developed. The stage -storage -discharge curve for a specific detention area (i.e., an infiltration basin) is used to compute an outflow hydrograph by hydraulically routing an inflow hydrograph through the detention facilities. This procedure calculates the relationship of the inflow hydrograph with the characteristics of the detention basin systems to determine the outflow, stage, and storage capacity of the detention systems for a given time during the specified storm event. Pipe sizing calculations for the closed pipe drainage system were performed with StormCAD, a computer program by Haestad Methods, Inc., utilizing the Rational Method to determine the runoff. The Intensity Duration Frequency (IDF) Curves for the Boston area were used to obtain the rainfall intensity data for the hydraulic design standard 25 -year storm event. The existing watershed boundaries for the site were determined based on the topography of the site which was obtained through an on -the -ground survey performed by SMC Surveying and Mapping Consultants. Tetra Tech 2 2.2 Sources of Data • SCS Technical Release No. 20 (TR-20) • SCS Technical Release No. 55 (TR-55) • U.S. Department of Commerce, Technical Paper No. 40 (TP-40), Rainfall Frequency Atlas of the United States. • Soil Survey of Middlesex County, Massachusetts (Natural Resources Conservation Service) • Intensity Duration Frequency (IDF) Curves for the Boston, Massachusetts Area 2.3 Rainfall Depths In accordance with the Massachusetts Department of Environmental Protection Stormwater Management Guidelines, the 2, 10, 25, and 100 -year storm events were analyzed. Type III -24 hour storms were used for the stormwater runoff calculations. The following are the rainfall depths used for each storm event. Table 2 Rainfall Depths Storm Event 24 hour Rainfall 2 -year 3.1 inches 10 -year 4.5 inches 25 -year 5.3 inches 100 -year 6.5 inches 2.4 Soil Conditions Natural Resources Conservation Service (NRCS) Middlesex County Soil Survey indicates that soils onsite consist of the Urban Land (Refer to the County Soils Map in Appendix G): Urban land consists of areas where 75 percent or more of the land is covered with impervious surfaces, such as buildings, pavement, industrial parks, and railroad yards. Urban land does not have a designated Hydrologic Soil Group (HSG); however for the purposes of the stormwater calculations HSG C is used. 2.5 Existing Stormwater Management 2.5.1 Existing Drainage System The existing drainage system consists of catch basins, roof leaders, manholes and closed drained pipes. Existing water quality treatment devices consists of leaching catch basins and an oil/grit separator. Tetra Tech 3 2.5.2 Watershed Under existing conditions, the site is divided into three (3) drainage subcatchment area. Characteristics of the subcatchment area is noted below and shown on Figure 2, Existing Watershed Map. There are two (2) Design Points for the site: • Design Point 1 (1R) — Existing closed drainage system located in Arsenal Street • Design Point 2 (2R) — An existing 24 inch reinforced concrete pipe located to the west of the proposed re -development project which ultimately discharges into the Charles River. Below is a description of each subcatchment: • Subcatchment 1S consists mostly of impervious surface associated with the parking lot for 58 Irving Street. Runoff from this subcatchment is collected via catch basins and is directed into a closed drainage system which discharges to design point 1 (1R). • Subcatchment 2S consists entirely of roof runoff associated with 58 Irving Street. Runoff from this subcatchment is collected via roof leaders and is directed into a closed drainage system which discharges to design point 2 (2R). • Subcatchment 3S consists mostly of impervious surface associated with the parking lot Runoff from this subcatchment is collected via catch basins and is directed into a closed drainage system which discharges to design point 2 (2R). 2.5.3 Existing Runoff Calculations In order to determine the peak rate of discharge for existing conditions, runoff hydrographs were generated for the storm events using the SCS TR-20 Method (refer to Appendix B, HydroCAD° Report). The existing stormwater discharge rates are shown in Table 3. Table 3 Existing Peak Runoff Rates Point of Analysis 2 -Year Storm (cfs) 10 -Year Storm (cfs) 25 -Year Storm (cfs) 100 -Year Storm (cfs) 1R 0.90 1.34 1.59 1.96 2R 22.07 33.03 29.25 48.54 *cfs = cubic feet per second 2.6 Proposed Stormwater Management 2.6.1 Proposed Drainage System The proposed drainage system consists of deep sump/hooded catch basins, roof leaders, drain manholes and high density polyethylene (HDPE) pipes (sized for a 25 year storm). Water quality treatment includes Stormceptor® treatment units and recharge is achieved via subsurface infiltration basins. Tetra Tech 4 2.6.2 Proposed Watershed For the analysis of proposed stormwater conditions the site is divided into twelve (12) subcatchment areas. Characteristics of each subcatchment area are noted below and shown on Figure 3, Proposed Watershed Map. • Subcatchment 1S consists of pervious and impervious surfaces associated with angled parking spaces located along Arsenal Street. Runoff from this subcatchment is collected via an existing catch basin located within Arsenal Street and is directed into a closed drainage system which discharges to design point 1 (1R). • Subcatchments lAS and 1BS consist mostly of impervious surface associated with the southeast portion of the driveway, the southern courtyard and the residential/retail building entrance. Runoff from this subcatchment is collected via catch basins and is directed into a closed drainage system which discharges to a subsurface infiltration basin (1P). The basin is equipped with an outlet control structure which discharges to design point 2 (2R). • Subcatchments 2AS and 2BS consists entirely of impervious surface associated with the residential/retail building. Runoff from this subcatchment is collected via roof leaders and is directed into a closed drainage system which discharges to a subsurface infiltration basin (2P). The basin is equipped with an outlet control structure which discharges to design point 2 (2R). • Subcatchments 2CS and 2DS consist mostly of impervious surface associated with the residential/retail building and the northern courtyard. Runoff from this subcatchment is collected via catch basins and is directed into a closed drainage system which discharges to a rain garden (5P). The rain garden is equipped with an outlet control structure which discharges to subsurface infiltration basin (2P) during large storm events. • Subcatchments 3S consists entirely of impervious surface associated with the roof from the retail/office building. Runoff from this subcatchment is collected via roof leaders and is directed into a closed drainage system which discharges to a subsurface infiltration basin (3P). The basin is equipped with an outlet control structure which discharges to design point 2 (2R). • Subcatchment 4S consists mostly of impervious surface associated with the southwest site entrance. Runoff from this subcatchment is collected via catch basins and is directed into a closed drainage system which discharges to a subsurface infiltration basin (4P). The basin is equipped with an outlet control structure which discharges to design point 2 (2R). • Subcatchment 5S consists entirely of pervious surface. Runoff from this subcatchment sheet flows to a rain garden (5P). The rain garden is equipped with an outlet control structure which discharges to subsurface infiltration basin (2P) during large storm events. Tetra Tech 5 • Subcatchment 6S consists mostly of impervious surface associated with the southwest site entrance. Runoff from this subcatchment is collected via catch basins and is directed into a closed drainage system which discharges to design point 2 (2R). • Subcatchment 7S consists entirely of pervious surface. Runoff from this subcatchment sheet flows towards the west were it is then collected via catch basins into a closed drainage system which discharges to design point 2 (2R). 2.6.3 Proposed Runoff Calculations In order to determine the peak rate of discharge for proposed conditions, runoff hydrographs were generated for the storm events using the SCS TR-20 Method (refer to Appendix B, HydroCAD® Report). Under the proposed conditions, runoff hydrographs were routed through the proposed stormwater management facilities. The proposed stormwater discharge rates are shown in Table 4. Table 4 Proposed Peak Runoff Rates Point of Analysis 2 -Year Storm (cfs) 10 -Year Storm (cfs) 25 -Year Storm (cfs) 100 -Year Storm (cfs) 1R 0.23 0.43 0.55 0.73 2R 1.78 5.67 12.42 21.78 *cfs = cubic feet per second 2.6.4 Storm Drainage Pipe System The proposed storm drainage collection system consists of roof drains, deep sump/hooded catch basins, manholes, water quality structures, and high density polyethylene (HDPE) pipes that will collect runoff from the rooftops, parking lot, and landscaped areas within the proposed project and discharge into the existing drainage system. All stormwater runoff will be routed through water quality structures for treatment prior to discharge into the existing drainage system which ultimately discharges into the Charles River. The proposed storm drainage collection system has been designed for a twenty five (25) year storm frequency utilizing the Rational Method and Manning's Equation. StormCAD was used to perform the hydraulic analysis for the stormwater management system. Refer to Appendix E for the StormCAD Report and Figure 4, Proposed Catch Basin Catchment Areas for the subcatchment drainage areas. The following criteria were used to design the pipe network: • Pipes shall be sized to convey the 25 -year storm event. • All drainage pipes shall have a minimum cover of 2 feet. • All drainage pipes with less than 2 feet of cover shall be ductile iron. • Rainfall intensity of 6.0 inches per hour for a 5 minute duration for the 25 -year storm frequency. Tetra Tech 6 • Manning's coefficient (n) of 0.012 for high density polyethylene pipe (HDPE) • Manning's coefficient (n) of 0.013 for reinforced concrete pipe (RCP) • Manholes shall be provided at all changes in direction or changes in pipe size. • Maximum pipe velocity shall be 10 feet per second (fps). 3.0 DEP Stormwater Standards The purpose of the Stormwater Management Plan is to provide a comprehensive framework for the long-term protection of natural resources in and around the Site from degradation as a result of stormwater discharges. This is achieved through the use of a variety of water quality and quantity control measures designed to decrease the amount of pollutants discharged from the Site and control discharge rates and volumes. The following sections describe the regulations pertinent to stormwater management and the specific components of the Stormwater Management Plan to be implemented at the Site. The ten standards contained in the DEP Stormwater Management policy relate to the protection of wetlands and water bodies, control of water quantity, recharge to groundwater, water quality and protection of critical areas, erosion/sedimentation control and stormwater maintenance. The following summarizes the proposed Project's compliance with the Stormwater Management Standards. 3.1 Standard No. 1 — Untreated Stormwater No new point discharges of untreated stormwater to resource areas are proposed. The site does not contain natural resource areas; however, proposed stormwater quality control improvements for the project includes street sweeping, deep sump/hooded catch basins, a rain garden, Stormceptor® treatment units and subsurface infiltration basins. 3.2 Standard No. 2 — Post -development Peak Discharge Rates Stormwater management systems shall be designed so that post development peak discharge rates do not exceed pre -development discharge rates. For redevelopment projects this standard must be met to the maximum extent possible. However, the proposed project will not increase the peak runoff rates from existing conditions, but in fact significantly reduce peak runoff rates. In order to determine the peak rate of discharge for existing and proposed conditions, runoff hydrographs were generated for the storm events using the SCS TR-20 Method (refer to Appendix B for HydroCAD® Report). Under the proposed conditions, the post -development runoff hydrographs were routed through the proposed drainage system and into the proposed stormwater management system. The following table summarizes the pre- and post -development peak runoff discharge rates determined in the hydrologic/hydraulic analyses performed for the project site. Tetra Tech 7 Table 5 Comparison of Peak Runoff Rates Point of Analysis 2 -Year Storm (cfs) 10 -Year Storm (cfs) 25 -Year Storm (cfs) 100 -Year Storm (cfs) Pre Post A Pre Post A Pre Post A Pre Post A 1R 0.90 0.23 -0.67 1.34 0.43 -0.91 1.59 0.55 -1.04 1.96 0.73 -1.23 2R 22.07 1.78 -20.29 33.03 5.67 -27.36 39.25 12.42 -26.83 48.54 21.78 -26.76 *cfs = cubic feet per second As shown in Table 5, proposed peak runoff rates for the project are significantly less than existing conditions for each storm event. The proposed site development will not increase the runoff to the existing drainage collection system located within Arsenal Street which ultimately discharges into the Charles River. 3.3 Standard No. 3 - Recharge to Groundwater The project site is located within soil type "urban land" which does not have a designated Hydrologic Soil Group (HSG); however for the purposes of the stormwater calculations HSG C was used. Based on the applicable MADEP recommendations for groundwater recharge rate for type "C" soils, 0.25 inches of runoff times total impervious area should be used. The total impervious area (roof, parking, sidewalks) is 6.22 acres. Therefore, the recommended groundwater recharge volume is [6.22 x (0.25/12)] = 0.13 acre-feet. The subsurface infiltration basins provide approximately 0.712 acre-feet of stormwater storage volume without discharge. Although redevelopment projects only need to meet Standard No. 3 maximum extent practicable, the incorporation of these infiltration basins exceeds the recharge requirement. Refer to Appendix C for Groundwater Recharge Calculations. Seasonal high groundwater elevations and infiltration rates in the vicinity of the proposed infiltration basins are based on subsurface information collected to date. Refer to Appendix G for a Memorandum prepared by Sanborn, Head & Associates, Inc. for estimated Rawls Rates and boring logs. Standard No. 4 - TSS Removal Best Management Practices (BMPs) will be used to provide water quality. The following BMPs will be provided on -site to treat the new impervious area on site: street sweeping, deep sump/hooded catch basins, a rain garden, Stormceptor® treatment units and StormTech® infiltration basins. 3.3.1 Street Sweeping The proposed design incorporates street sweeping as a BMP to control the amount of sediment that enters the drainage system. Street sweeping will be conducted on a quarterly average and be primarily scheduled in the spring and fall. In accordance with DEP Standards a 5% total suspended solids (TSS) removal rate is credited for this BMP. 3.3.2 Deep Sump/Hooded Catch Basins All proposed catch basins will be deep sump/hooded catch basins, which will serve to trap sediment and floatables before entering the stormwater management system. Sumps will be Tetra Tech 8 four -feet deep. Catch basins will be inspected quarterly and, if necessary, cleaned when sediment reaches half full depth to ensure that the catch basins are working in their intended fashion and that they are free of debris. Sediments and hydrocarbons shall be properly handled and disposed of, in accordance with local, state, and federal requirements. All catch basins will be installed with sediment sumps and oil hoods. In accordance with DEP Standards a 25% total suspended solids (TSS) removal rate is credited for this BMP. 3.3.3 Rain Gardens The proposed design of the on -site drainage system incorporates one rain garden. Rain gardens uses soils plants and microbes to treat stormwater before it is infiltrated and/or discharged. In accordance with DEP Standards a 90% total suspended solids (TSS) removal rate is credited for this BMP. 3.3.4 Stormceptor® Treatment Units The proposed design of the on -site drainage system will incorporate Stormceptor® units prior to discharging to the subsurface infiltration basins. In accordance with DEP Standards the MASTEP laboratory study found the Stormceptor STC 900 achieved 75% removal of "Bulk TSS", which MASTEP considers equivalent to suspended sediment concentration (SSC). While this information references the STC 900, the performance of the structures can be scaled upward or downward based on the size of the units, and areas and flows to be treated. The TSS Removal Calculations in Appendix D are representative of the MASTEP 75% removal rate. However, according to the Stormceptor® sizing program based upon independent test data, the Stormceptor® structures specified on the plans will achieve TSS removal rates in excess of 75%. Refer to Appendix D for Water Quality Structure Efficiency Calculations. 3.3.5 StormTech® Infiltration Basin The stormwater management system includes four (4) subsurface infiltration basins to treat runoff prior to discharging into the existing drainage collection system located within Arsenal Street. The infiltration basins consist of a series of chambers surrounded with drain rock and filter fabric. Runoff from paved areas is directed through deep sump/hooded catch basins and Stormceptor® treatment units prior to discharging into the infiltration basin. In accordance with DEP Standards a 80% total suspended solids (TSS) removal rate is credited for this BMP. Although redevelopment projects are not required to achieve 80% removal of TSS, the incorporation of these BMPs will achieve a cumulative TSS removal rate of greater than 80%. Refer to Appendix D for Water Quality Calculations and a copy of the MASTEP Report. 3.4 Standard No. 5 - Higher Potential Pollutant Loads The project will generate in excess of 1,000 vehicles per day and therefore may be considered a higher pollutant load generator. Land uses with higher pollutant loads require 44% TSS removal prior to discharging into an infiltration BMP. In addition the BMP must be designed to treat the one inch water quality volume. Tetra Tech 9 3.5 Standard No. 6 - Protection of Critical Areas Critical areas are Outstanding Resource Waters (ORWs), shellfish beds, swimming beaches, cold water fisheries, and recharge areas for public drinking water supplies. The project site is not located within a critical area. 3.6 Standard No. 7 - Redevelopment Projects Redevelopment projects include development, rehabilitation, expansion and phased projects on previously developed sites, provided the redevelopment results in no net increase in impervious area. As such, the proposed Project qualifies as a redevelopment project and is required to meet the following Stormwater Management Standards to the maximum extent practicable: Standard 2 and 3, and the pretreatment and structural best management practice requirements of Standards 4, 5, and 6. The redevelopment Project results in a net reduction of impervious surface of approximately 1 acre. 3.7 Standard No. 8 - Erosion/Sediment Control The Project will result in the disturbance of greater than one (1) acre of land, a Storm Water Pollution Prevention Plan (SWPPP) will be prepared in accordance with the EPA NPDES General Permit for Discharges from Construction Activities, effective date February 16, 2012, and submitted to the EPA and the Town of Watertown prior to commencement of construction activities. The SWPPP will be prepared describing the specific practices, installation methods and inspection requirements for temporary and permanent erosion prevention and sediment control practices. The SWPPP will follow the template developed by the U.S. EPA and filed with the Salem Conservation Commission. At a minimum, the SWPPP will include the following measures: • Minimize the extent and time of exposed soils; • Provide perimeter sediment control including silt fence and/or compost filter tubes; • Provide catch basin inlet protection including geotextile filter fabric and gravel drop; • Minimize sediment track out with stabilized construction exits; • Dedicated concrete washout areas; • Control discharges from soil stockpiles include temporary erosion control measures and perimeter sediment controls; • Minimize dust and soil compaction; • Temporary stormwater management practices including basins, traps and swales; • Dewatering requirements; • Temporary and permanent stabilization requirements, including seeding, mulching and matting; • Good housekeeping pollution prevention measures; Tetra Tech 10 • Maintenance requirements; and • Inspection, recordkeeping, and reporting requirements 3.8 Standard No. 9 - Operation/Maintenance Plan The Stormwater Management System will be the overall responsibility of the Owner. An Operations and Maintenance Plan is included in Appendix F. 3.9 Standard No. 10 - Illicit Discharge To the best of the owners and engineers knowledge, no illicit discharges exist on Site and no illicit discharges will be incorporated as part of the proposed redevelopment Project into the proposed stormwater management system. 4.0 Conclusion The stormwater management system addresses both the quantity and quality of stormwater runoff from the Site and conforms to the ten (10) standards outlined by the Massachusetts Department of Environmental Protection Stormwater Policy. Tetra Tech 11 ti IN •. �-_- •'� AL& -� N �■ iilt=1:I a fALFAmro iL JIM 7 w I- 2 0 0 0 w x rn w O z_ CO I— X w_ CO w U- I - 0 a d 0) 0 0 M 0 co co O 0 I` N a 0 a co co 7 N M 0 N r— i LEGEND: 1S SUBCATCHMENT 1P POND 1 R HYDROLOGIC REACH * DESIGN POINT SUBCATCHMENT BOUNDARY — 4 — - — — Tc FLOW PATH NOTES: 1. THE NATURAL RESOURCES CONSERVATION SERVICE (NRCS) MIDDLESEX COUNTY SOIL SURVEY INDICATE THAT THE SOIL ON -SITE CONSISTS OF URBAN LAND. GRAVEL GRAVEL 69 �gpoKENI +866 +2828 6 CRUSHED STO + 395 ay! +39.85 METAL POST CHAIN BARRI S I ALL 0o80 280 029 +27.16 01,111 2056 96 BIT CONC SDC +27.22 2730 46 MW +a„CONC =27 65 26----T. RI/ 01 'L'NGER VEHICLE GRAVED DEBRIS 089 PILE M R=26, 080 Mf1t 26z+ BIT COND 91 40 10 *1,0;0 88 201.02 0 EL GUARDRAIL L SEWER 41 7 PUMP R=01 35 a100R <r. 50' 100' SCALE: 1" = 100' D.20 6 0" QJ '''1317 GONG BIT CONC R.26 81 RET WALL JERSEY SILT021 MP CONC PAD 32 10 3.2„35y ,co oo CB NPV R3H R- 816 WG ?`38.51 7MH 1=3,9 ARSENAL STREET (PUBLIC - 66' WIDE) %37 T EL RD 1,37 82 00 ORaz27 R=37,7 VIDRICH RC.M„ R=36,50 NO OTHER PIPES SMH OBSERVED R 31 10 19 / SILT LRBASE E9049 30 3602 y8-207 +3676 TETRA TECH www.tetratech.com One Grant Street Framingham, MA 01701 Phone: (508) 903-2000 Fax: (508) 903-2001 Hanover R.S. Limited Partnership 58 Irving Street & 202-204 Arsenal Street Watertown, MA Existing Watershed Map Project No.: 143-26700-13001 Date: November 12, 2013 Designed By: SJW Figure 2 Bar Measures 1 inch t- 0 a a w x w a 0 w 0 0- 0 a in w J f- 0 0 c a 0 0 co C) a N 0 0 a co N N M 0 N r - LEGEND: 1S SUBCATCHMENT 1P POND HYDROLOGIC REACH DESIGN POINT SUBCATCHMENT BOUNDARY —4---- TcFLOWPATH 1R NOTES: 1. THE NATURAL RESOURCES CONSERVATION SERVICE (NRCS) MIDDLESEX COUNTY SOIL SURVEY INDICATE THAT THE SOIL ON -SITE CONSISTS OF URBAN LAND. 0 ©NIH N � s � O III III IM �A& 1111 '— ,� ���01/ o� M=rs , ,elf Ai -106/;ff%... .D _359 = ate• . ,_ ..MMEOP' a ,,59 =41.1 0 X11 50' 100' SCALE: 1" = 100' R-37 90 3 - 6 FNDAft 19 I i 1 TETRA TECH www.tetratech.com One Grant Street Framingham, MA 01701 Phone: (508) 903-2000 Fax: (508) 903-2001 Hanover R.S. Limited Partnership 58 Irving Street & 202-204 Arsenal Street Watertown, MA Proposed Watershed Map Project No.: 143-26700-13001 Date: November 12, 2013 Designed By: SJW Figure 3 Bar Measures 1 inch 11/7/2013 2:43:43 PM - P:\26700\143-26700-13001\CAD\SUPPORTFILES\CB CATCHMENT AREAS.DWG - WHITE, SARA l LEGEND: SUBCATCHMENT BOUNDARY o Or. [ ¶7 L. 0 50' 100' SCALE: 1" = 100' GAT (707) TLIFI TETRA TECH www.tetratech.com One Grant Street Framingham, MA 01701 Phone: (508) 903-2000 Fax: (508) 903-2001 Hanover R.S. Limited Partnership 58 Irving Street & 202-204 Arsenal Street Watertown, MA Proposed Catch Basin Catchment Areas Project No.: 143-26700-13001 Date: November 12, 2013 Designed By: SJW Figure 4 J Copyright: Tetra Tech Bar Measures 1 inch Appendix A Stormwater Checklist Important: When filling out forms on the computer, use only the tab key to move your cursor - do not use the return key. Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report A. Introduction A Stormwater Report must be submitted with the Notice of Intent permit application to document compliance with the Stormwater Management Standards. The following checklist is NOT a substitute for the Stormwater Report (which should provide more substantive and detailed information) but is offered here as a tool to help the applicant organize their Stormwater Management documentation for their Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist, the Stormwater Report must contain the engineering computations and supporting information set forth in 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. 1 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.doc • 04/01/08 Stormwater Report Checklist • Page 1 of 8 Massachusetts 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 Sign ture and Date /1. Checklist Project Type: Is the application for new development, redevelopment, or a mix of new and redevelopment? O New development ® Redevelopment ❑ Mix of New Development and Redevelopment Stormwater Checklist.doc • 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.doc • 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. 21E 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. 21E site or a solid waste landfill and a mounding analysis is included. 1 80% TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used. Stormwater Checklist.doc • 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.doc • 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 V2" 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.doc • 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.doc • 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 BMP 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.doc • 04/01/08 Stormwater Report Checklist • Page 8 of 8 Appendix B HydroCADR Report Existing Conditions HydroCAD Report C1S) 2S �3S) 1 1R 2R DESIGN POINT 1 DESIGN POINT 2 Subcat Reach Routing Diagram for Existing Watershed Prepared by Tetra Tech, Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Existing Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Area Listing (all nodes) Area CN Description (acres) (subcatchment-numbers) 0.760 74 >75% Grass cover, Good, HSG C (1S, 3S) 4.170 98 Pavement (1S, 3S) 3.070 98 Roof (2S, 3S) 8.000 96 TOTAL AREA Printed 11/7/2013 Page 2 Existing Watershed Type III 24 -hr 2 -year Rainfall=3.10" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 3 Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Subcatchment2S: Subcatchment3S: Reach 1R: DESIGN POINT 1 Reach 2R: DESIGN POINT 2 Runoff Area=0.300 ac 90.00% Impervious Runoff Depth=2.65" Tc=5.0 min CN=96 Runoff=0.90 cfs 0.066 af Runoff Area=3.000 ac 100.00% Impervious Runoff Depth=2.87" Tc=5.0 min CN=98 Runoff=9.34 cfs 0.717 af Runoff Area=4.700 ac 84.47% Impervious Runoff Depth=2.45" Flow Length=1,112' Tc=6.2 min CN=94 Runoff=12.86 cfs 0.958 af Inflow=0.90 cfs 0.066 af Outflow=0.90 cfs 0.066 af Inflow=22.07 cfs 1.675 af Outflow=22.07 cfs 1.675 af Total Runoff Area = 8.000 ac Runoff Volume = 1.742 af Average Runoff Depth = 2.61" 9.50% Pervious = 0.760 ac 90.50% Impervious = 7.240 ac Existing Watershed Type III 24 -hr 2 -year Rainfall=3.10" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment 1S: Runoff = 0.90 cfs @ 12.07 hrs, Volume= 0.066 af, Depth= 2.65" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description 0.270 98 Pavement 0.030 74 >75% Grass cover, Good, HSG C 0.300 96 Weighted Average 0.030 10.00% Pervious Area 0.270 90.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 9.34 cfs © 12.07 hrs, Volume= 0.717 af, Depth= 2.87" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description 3.000 98 Roof 3.000 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 3S: Runoff = 12.86 cfs @ 12.09 hrs, Volume= 0.958 af, Depth= 2.45" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description * 0.070 98 Roof * 3.900 98 Pavement 0.730 74 >75% Grass cover, Good, HSG C 4.700 94 Weighted Average 0.730 15.53% Pervious Area 3.970 84.47% Impervious Area Existing Watershed Type III 24 -hr 2 -year Rainfall=3.10" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 5 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.5 50 0.0500 1.70 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.10" 0.4 101 0.0500 4.54 Shallow Concentrated Flow, Paved Kv= 20.3 fps 1.2 176 0.0030 2.48 1.95 Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 0.2 65 0.0140 5.37 4.22 Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 0.4 173 0.0290 6.84 3.73 Pipe Channel, 10.0" Round Area= 0.5 sf Perim= 2.6' r= 0.21' n= 0.013 0.1 47 0.0340 7.41 4.04 Pipe Channel, 10.0" Round Area= 0.5 sf Perim= 2.6' r= 0.21' n= 0.013 2.2 164 0.0010 1.27 0.69 Pipe Channel, 10.0" Round Area= 0.5 sf Perim= 2.6' r= 0.21' n= 0.013 1.2 336 0.0040 4.55 14.31 Pipe Channel, 24.0" Round Area= 3.1 sf Perim= 6.3' r= 0.50' n= 0.013 6.2 1,112 Total Summary for Reach 1R: DESIGN POINT 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.300 ac, 90.00% Impervious, Inflow Depth = 2.65" for 2 -year event Inflow = 0.90 cfs @ 12.07 hrs, Volume= 0.066 of Outflow = 0.90 cfs @ 12.07 hrs, Volume= 0.066 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Summary for Reach 2R: DESIGN POINT 2 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 7.700 ac, 90.52% Impervious, Inflow Depth = 2.61" for 2 -year event Inflow = 22.07 cfs @ 12.08 hrs, Volume= 1.675 af Outflow = 22.07 cfs @ 12.08 hrs, Volume= 1.675 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Existing Watershed Type III 24 -hr 10 -year Rainfall=4.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 6 Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Subcatchment2S: Subcatchment3S: Reach 1R: DESIGN POINT 1 Reach 2R: DESIGN POINT 2 Runoff Area=0.300 ac 90.00% Impervious Runoff Depth=4.04" Tc=5.0 min CN=96 Runoff=1.34 cfs 0.101 af Runoff Area=3.000 ac 100.00% Impervious Runoff Depth=4.26" Tc=5.0 min CN=98 Runoff=13.66 cfs 1.066 af Runoff Area=4.700 ac 84.47% Impervious Runoff Depth=3.82" Flow Length=1,112' Tc=6.2 min CN=94 Runoff=19.55 cfs 1.494 af Inflow=1.34 cfs 0.101 af Outflow=1.34 cfs 0.101 af Inflow=33.03 cfs 2.560 af Outflow=33.03 cfs 2.560 af Total Runoff Area = 8.000 ac Runoff Volume = 2.661 af Average Runoff Depth = 3.99" 9.50% Pervious = 0.760 ac 90.50% Impervious = 7.240 ac Existing Watershed Type III 24 -hr 10 -year Rainfall=4.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 7 Summary for Subcatchment 1S: Runoff = 1.34 cfs @ 12.07 hrs, Volume= 0.101 af, Depth= 4.04" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description 0.270 98 Pavement 0.030 74 >75% Grass cover, Good, HSG C 0.300 96 Weighted Average 0.030 10.00% Pervious Area 0.270 90.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 13.66 cfs @ 12.07 hrs, Volume= 1.066 af, Depth= 4.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description 3.000 98 Roof 3.000 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 3S: Runoff = 19.55 cfs @ 12.09 hrs, Volume= 1.494 af, Depth= 3.82" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description 0.070 98 Roof 3.900 98 Pavement 0.730 74 >75% Grass cover, Good, HSG C 4.700 94 Weighted Average 0.730 15.53% Pervious Area 3.970 84.47% Impervious Area Existing Watershed Type III 24 -hr 10 -year Rainfall=4.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 8 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.5 50 0.0500 1.70 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.10" 0.4 101 0.0500 4.54 Shallow Concentrated Flow, Paved Kv= 20.3 fps 1.2 176 0.0030 2.48 1.95 Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 0.2 65 0.0140 5.37 4.22 Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 0.4 173 0.0290 6.84 3.73 Pipe Channel, 10.0" Round Area= 0.5 sf Perim= 2.6' r= 0.21' n= 0.013 0.1 47 0.0340 7.41 4.04 Pipe Channel, 10.0" Round Area= 0.5 sf Perim= 2.6' r= 0.21' n= 0.013 2.2 164 0.0010 1.27 0.69 Pipe Channel, 10.0" Round Area= 0.5 sf Perim= 2.6' r= 0.21' n= 0.013 1.2 336 0.0040 4.55 14.31 Pipe Channel, 24.0" Round Area= 3.1 sf Perim= 6.3' r= 0.50' n= 0.013 6.2 1,112 Total Summary for Reach 1R: DESIGN POINT 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.300 ac, 90.00% Impervious, Inflow Depth = 4.04" for 10 -year event Inflow = 1.34 cfs @ 12.07 hrs, Volume= 0.101 af Outflow = 1.34 cfs @ 12.07 hrs, Volume= 0.101 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Summary for Reach 2R: DESIGN POINT 2 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 7.700 ac, 90.52% Impervious, Inflow Depth = 3.99" for 10 -year event Inflow = 33.03 cfs @ 12.08 hrs, Volume= 2.560 af Outflow = 33.03 cfs @ 12.08 hrs, Volume= 2.560 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Existing Watershed Type III 24 -hr 25 -year Rainfall=5.30" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 9 Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Subcatchment2S: Subcatchment3S: Reach 1R: DESIGN POINT 1 Reach 2R: DESIGN POINT 2 Runoff Area=0.300 ac 90.00% Impervious Runoff Depth=4.83" Tc=5.0 min CN=96 Runoff=1.59 cfs 0.121 af Runoff Area=3.000 ac 100.00% Impervious Runoff Depth=5.06" Tc=5.0 min CN=98 Runoff=16.12 cfs 1.266 af Runoff Area=4.700 ac 84.47% Impervious Runoff Depth=4.60" Flow Length=1,112' Tc=6.2 min CN=94 Runoff=23.34 cfs 1.803 af Inflow=1.59 cfs 0.121 af Outflow=1.59 cfs 0.121 af Inflow=39.25 cfs 3.069 af Outflow=39.25 cfs 3.069 af Total Runoff Area = 8.000 ac Runoff Volume = 3.190 af Average Runoff Depth = 4.78" 9.50% Pervious = 0.760 ac 90.50% Impervious = 7.240 ac Existing Watershed Type III 24 -hr 25 -year Rainfall=5.30" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 10 Summary for Subcatchment 1S: Runoff = 1.59 cfs @ 12.07 hrs, Volume= 0.121 af, Depth= 4.83" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description 0.270 98 Pavement 0.030 74 >75% Grass cover, Good, HSG C 0.300 96 Weighted Average 0.030 10.00% Pervious Area 0.270 90.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 16.12 cfs @ 12.07 hrs, Volume= 1.266 af, Depth= 5.06" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description 3.000 98 Roof 3.000 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 3S: Runoff = 23.34 cfs @ 12.09 hrs, Volume= 1.803 af, Depth= 4.60" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description 0.070 98 Roof 3.900 98 Pavement 0.730 74 >75% Grass cover, Good, HSG C 4.700 94 Weighted Average 0.730 15.53% Pervious Area 3.970 84.47% Impervious Area Existing Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Tc Length Slope (min) (feet) (ft/ft) Velocity Capacity Description (ft/sec) (cfs) Type III 24 -hr 25 -year Rainfall=5.30" Printed 11/7/2013 Page 11 0.5 50 0.0500 1.70 0.4 101 0.0500 4.54 1.2 176 0.0030 2.48 1.95 0.2 65 0.0140 5.37 4.22 0.4 173 0.0290 6.84 3.73 0.1 47 0.0340 7.41 4.04 2.2 164 0.0010 1.27 0.69 1.2 336 0.0040 4.55 14.31 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.10" Shallow Concentrated Flow, Paved Kv= 20.3 fps Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 Pipe Channel, 10.0" Round Area= 0.5 sf Perim= 2.6' r= 0.21' n= 0.013 Pipe Channel, 10.0" Round Area= 0.5 sf Perim= 2.6' r= 0.21' n= 0.013 Pipe Channel, 10.0" Round Area= 0.5 sf Perim= 2.6' r= 0.21' n= 0.013 Pipe Channel, 24.0" Round Area= 3.1 sf Perim= 6.3' r= 0.50' n= 0.013 6.2 1,112 Total Summary for Reach 1R: DESIGN POINT 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = Inflow = Outflow = 0.300 ac, 90.00% Impervious, Inflow Depth = 4.83" for 25 -year event 1.59 cfs @ 12.07 hrs, Volume= 0.121 af 1.59 cfs @ 12.07 hrs, Volume= 0.121 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Summary for Reach 2R: DESIGN POINT 2 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = Inflow = Outflow = 7.700 ac, 90.52% Impervious, Inflow Depth = 4.78" for 25 -year event 39.25 cfs @ 12.08 hrs, Volume= 3.069 af 39.25 cfs @ 12.08 hrs, Volume= 3.069 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Existing Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 12 Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Subcatchment2S: Subcatchment3S: Reach 1R: DESIGN POINT 1 Reach 2R: DESIGN POINT 2 Runoff Area=0.300 ac 90.00% Impervious Runoff Depth=6.03" Tc=5.0 min CN=96 Runoff=1.96 cfs 0.151 af Runoff Area=3.000 ac 100.00% Impervious Runoff Depth=6.26" Tc=5.0 min CN=98 Runoff=19.81 cfs 1.565 af Runoff Area=4.700 ac 84.47% Impervious Runoff Depth=5.79" Flow Length=1,112' Tc=6.2 min CN=94 Runoff=28.99 cfs 2.269 af Inflow=1.96 cfs 0.151 af Outflow=1.96 cfs 0.151 af Inflow=48.54 cfs 3.834 af Outflow=48.54 cfs 3.834 af Total Runoff Area = 8.000 ac Runoff Volume = 3.985 af Average Runoff Depth = 5.98" 9.50% Pervious = 0.760 ac 90.50% Impervious = 7.240 ac Existing Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 13 Summary for Subcatchment 1S: Runoff = 1.96 cfs @ 12.07 hrs, Volume= 0.151 af, Depth= 6.03" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description 0.270 98 Pavement 0.030 74 >75% Grass cover, Good, HSG C 0.300 96 Weighted Average 0.030 10.00% Pervious Area 0.270 90.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 19.81 cfs @ 12.07 hrs, Volume= 1.565 af, Depth= 6.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description 3.000 98 Roof 3.000 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 3S: Runoff = 28.99 cfs @ 12.09 hrs, Volume= 2.269 af, Depth= 5.79" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description 0.070 98 Roof 3.900 98 Pavement 0.730 74 >75% Grass cover, Good, HSG C 4.700 94 Weighted Average 0.730 15.53% Pervious Area 3.970 84.47% Impervious Area Existing Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Tc Length Slope (min) (feet) (ft/ft) Velocity Capacity Description (ft/sec) (cfs) Type III 24 -hr 100 -year Rainfall=6.50" Printed 11/7/2013 Page 14 0.5 50 0.0500 1.70 0.4 101 0.0500 4.54 1.2 176 0.0030 2.48 1.95 0.2 65 0.0140 5.37 4.22 0.4 173 0.0290 6.84 3.73 0.1 47 0.0340 7.41 4.04 2.2 164 0.0010 1.27 0.69 1.2 336 0.0040 4.55 14.31 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.10" Shallow Concentrated Flow, Paved Kv= 20.3 fps Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 Pipe Channel, 12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25' n= 0.013 Pipe Channel, 10.0" Round Area= 0.5 sf Perim= 2.6' r= 0.21' n= 0.013 Pipe Channel, 10.0" Round Area= 0.5 sf Perim= 2.6' r= 0.21' n= 0.013 Pipe Channel, 10.0" Round Area= 0.5 sf Perim= 2.6' r= 0.21' n= 0.013 Pipe Channel, 24.0" Round Area= 3.1 sf Perim= 6.3' r= 0.50' n= 0.013 6.2 1,112 Total Summary for Reach 1R: DESIGN POINT 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = Inflow = Outflow = 0.300 ac, 90.00% Impervious, Inflow Depth = 6.03" for 100 -year event 1.96 cfs @ 12.07 hrs, Volume= 0.151 af 1.96 cfs @ 12.07 hrs, Volume= 0.151 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Summary for Reach 2R: DESIGN POINT 2 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = Inflow = Outflow = 7.700 ac, 90.52% Impervious, Inflow Depth = 5.97" for 100 -year event 48.54 cfs @ 12.08 hrs, Volume= 3.834 af 48.54 cfs @ 12.08 hrs, Volume= 3.834 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Proposed Conditions HydroCAD Report 0 C 1AS) (1 BSI 1R DESIGN POINT 1 Subcat COU TYARD INFILTRATION BA N 1 Reach ROOF 3P INFILTRATIO 3 2R 4S) C 2AS) (2BS) 0 (2CS) (2DS) RAIN GARGEN RTYARD TION BASIN 2 DESIGN POINT 2 Routing Diagram for Proposed Watershed Prepared by Tetra Tech, Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Proposed Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Area Listing (all nodes) Area CN Description (acres) (subcatchment-numbers) Printed 11/7/2013 Page 2 1.780 74 >75% Grass cover, Good, HSG C (1 AS, IBS, 1S, 2CS, 2DS, 3S, 4S, 5S, 6S, 7S) 3.420 98 Pavement (1AS, IBS, 1S, 2CS, 2DS, 3S, 4S, 6S) 2.800 98 Roof (2AS, 2BS) 8.000 93 TOTAL AREA Proposed Watershed Type III 24 -hr 2 -year Rainfall=3.10" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 3 Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1AS: Subcatchment 1 BS: COURTYARD Subcatchment 1S: Subcatchment2AS: ROOF Subcatchment2BS: GARAGE Subcatchment2CS: Subcatchment2DS: COURTYARD Subcatchment 3S: ROOF Subcatchment4S: Subcatchment 5S: Subcatchment 6S: Subcatchment 7S: Reach 1R: DESIGN POINT 1 Reach 2R: DESIGN POINT 2 Runoff Area=1.330 ac 85.71% Impervious Runoff Depth=2.55" Tc=5.0 min CN=95 Runoff=3.90 cfs 0.282 af Runoff Area=0.230 ac 91.30% Impervious Runoff Depth=2.65" Tc=5.0 min CN=96 Runoff=0.69 cfs 0.051 af Runoff Area=0.140 ac 28.57% Impervious Runoff Depth=1.39" Tc=5.0 min CN=81 Runoff=0.23 cfs 0.016 af Runoff Area=2.060 ac 100.00% Impervious Runoff Depth=2.87" Tc=5.0 min CN=98 Runoff=6.42 cfs 0.492 af Runoff Area=0.740 ac 100.00% Impervious Runoff Depth=2.87" Tc=5.0 min CN=98 Runoff=2.31 cfs 0.177 af Runoff Area=0.640 ac 57.81% Impervious Runoff Depth=1.91" Tc=5.0 min CN=88 Runoff=1.48 cfs 0.102 of Runoff Area=0.280 ac 89.29% Impervious Runoff Depth=2.55" Tc=5.0 min CN=95 Runoff=0.82 cfs 0.059 af Runoff Area=0.850 ac 82.35% Impervious Runoff Depth=2.45" Tc=5.0 min CN=94 Runoff=2.43 cfs 0.173 af Runoff Area=0.350 ac 85.71% Impervious Runoff Depth=2.55" Tc=5.0 min CN=95 Runoff=1.03 cfs 0.074 af Runoff Area=0.550 ac 0.00% Impervious Runoff Depth=0.97" Tc=5.0 min CN=74 Runoff=0.61 cfs 0.045 af Runoff Area=0.550 ac 74.55% Impervious Runoff Depth=2.26" Tc=5.0 min CN=92 Runoff=1.47 cfs 0.103 of Runoff Area=0.280 ac 0.00% Impervious Runoff Depth=0.97" Tc=5.0 min CN=74 Runoff=0.31 cfs 0.023 af Inflow=0.23 cfs 0.016 af Outflow=0.23 cfs 0.016 af Inflow=1.78 cfs 0.126 af Outflow=1.78 cfs 0.126 af Pond 1P: INFILTRATION BASIN 1 Peak Elev=26.49' Storage=6,727 cf Inflow=4.59 cfs 0.333 af Discarded=0.23 cfs 0.333 af Primary=0.00 cfs 0.000 af Outflow=0.23 cfs 0.333 af Pond 2P: INFILTRATION BASIN 2 Peak Elev=27.56' Storage=11,244 cf Inflow=8.72 cfs 0.669 af Discarded=0.61 cfs 0.669 af Primary=0.00 cfs 0.000 af Outflow=0.61 cfs 0.669 af Proposed Watershed Type III 24 -hr 2 -year Rainfall=3.10" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 4 Pond 3P: INFILTRATION BASIN 3 Peak Elev=28.67' Storage=3,597 cf Inflow=2.43 cfs 0.173 af Discarded=0.12 cfs 0.173 af Primary=0.00 cfs 0.000 af Outflow=0.12 cfs 0.173 af Pond 4P: INFILTRATION BASIN 4 Peak Elev=26.44' Storage=1,919 cf Inflow=1.03 cfs 0.074 af Discarded=0.03 cfs 0.074 af Primary=0.00 cfs 0.000 af Outflow=0.03 cfs 0.074 af Pond 5P: RAIN GARGEN Peak Elev=27.82' Storage=8,961 cf Inflow=2.91 cfs 0.206 af 12.0" Round Culvert n=0.013 L=66.0' S=0.0208 '/' Outflow=0.00 cfs 0.000 af Total Runoff Area = 8.000 ac Runoff Volume = 1.598 af Average Runoff Depth = 2.40" 22.25% Pervious = 1.780 ac 77.75% Impervious = 6.220 ac Proposed Watershed Type III 24 -hr 2 -year Rainfall=3.10" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment lAS: Runoff = 3.90 cfs @ 12.07 hrs, Volume= 0.282 af, Depth= 2.55" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description 1.140 98 Pavement 0.190 74 >75% Grass cover, Good, HSG C 1.330 95 Weighted Average 0.190 14.29% Pervious Area 1.140 85.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 1 BS: COURTYARD Runoff = 0.69 cfs © 12.07 hrs, Volume= 0.051 af, Depth= 2.65" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description 0.210 98 Pavement 0.020 74 >75% Grass cover, Good, HSG C 0.230 96 Weighted Average 0.020 8.70% Pervious Area 0.210 91.30% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 1S: Runoff = 0.23 cfs @ 12.08 hrs, Volume= 0.016 af, Depth= 1.39" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description 0.040 98 Pavement 0.100 74 >75% Grass cover, Good, HSG C 0.140 81 Weighted Average 0.100 71.43% Pervious Area 0.040 28.57% Impervious Area Proposed Watershed Type III 24 -hr 2 -year Rainfall=3.10" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 6 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2AS: ROOF Runoff = 6.42 cfs @ 12.07 hrs, Volume= 0.492 af, Depth= 2.87" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description * 2.060 98 Roof 2.060 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2BS: GARAGE Runoff = 2.31 cfs @ 12.07 hrs, Volume= 0.177 af, Depth= 2.87" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description 0.740 98 Roof 0.740 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Runoff Summary for Subcatchment 2CS: = 1.48 cfs @ 12.07 hrs, Volume= 0.102 af, Depth= 1.91" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description 0.370 98 Pavement 0.270 74 >75% Grass cover, Good, HSG C 0.640 88 Weighted Average 0.270 42.19% Pervious Area 0.370 57.81% Impervious Area Proposed Watershed Type III 24 -hr 2 -year Rainfall=3.10" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 7 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2DS: COURTYARD Runoff = 0.82 cfs @ 12.07 hrs, Volume= 0.059 af, Depth= 2.55" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description 0.250 98 Pavement 0.030 74 >75% Grass cover, Good, HSG C 0.280 95 Weighted Average 0.030 10.71% Pervious Area 0.250 89.29% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Runoff Summary for Subcatchment 3S: ROOF = 2.43 cfs @ 12.07 hrs, Volume= 0.173 af, Depth= 2.45" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description 0.700 98 Pavement 0.150 74 >75% Grass cover, Good, HSG C 0.850 94 Weighted Average 0.150 17.65% Pervious Area 0.700 82.35% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 4S: Runoff = 1.03 cfs @ 12.07 hrs, Volume= 0.074 af, Depth= 2.55" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Proposed Watershed Type III 24 -hr 2 -year Rainfall=3.10" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 8 Area (ac) CN Description 0.300 98 Pavement 0.050 74 >75% Grass cover, Good, HSG C 0.350 95 Weighted Average 0.050 14.29% Pervious Area 0.300 85.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 5S: Runoff = 0.61 cfs @ 12.08 hrs, Volume= 0.045 af, Depth= 0.97" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description 0.550 74 >75% Grass cover, Good, HSG C 0.550 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Runoff Direct Entry, Summary for Subcatchment 6S: 1.47 cfs @ 12.07 hrs, Volume= 0.103 af, Depth= 2.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description 0.410 98 Pavement 0.140 74 >75% Grass cover, Good, HSG C 0.550 92 Weighted Average 0.140 25.45% Pervious Area 0.410 74.55% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Proposed Watershed Type III 24 -hr 2 -year Rainfall=3.10" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 9 Summary for Subcatchment 7S: Runoff = 0.31 cfs @ 12.08 hrs, Volume= 0.023 af, Depth= 0.97" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 2 -year Rainfall=3.10" Area (ac) CN Description 0.280 74 >75% Grass cover, Good, HSG C 0.280 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Reach 1R: DESIGN POINT 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.140 ac, 28.57% Impervious, Inflow Depth = 1.39" for 2 -year event Inflow = 0.23 cfs @ 12.08 hrs, Volume= 0.016 af Outflow = 0.23 cfs @ 12.08 hrs, Volume= 0.016 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Summary for Reach 2R: DESIGN POINT 2 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 7.860 ac, 78.63% Impervious, Inflow Depth = 0.19" for 2 -year event Inflow = 1.78 cfs @ 12.07 hrs, Volume= 0.126 of Outflow = 1.78 cfs @ 12.07 hrs, Volume= 0.126 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Summary for Pond 1P: INFILTRATION BASIN 1 Inflow Area = 1.560 ac, 86.54% Impervious, Inflow Depth = 2.56" for 2 -year event Inflow = 4.59 cfs @ 12.07 hrs, Volume= 0.333 af Outflow = 0.23 cfs @ 10.63 hrs, Volume= 0.333 af, Atten= 95%, Lag= 0.0 min Discarded = 0.23 cfs @ 10.63 hrs, Volume= 0.333 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 26.49' @ 14.12 hrs Surf.Area= 4,120 sf Storage= 6,727 cf Flood Elev= 27.50' Surf.Area= 4,120 sf Storage= 8,406 cf Plug -Flow detention time= 255.3 min calculated for 0.333 af (100% of inflow) Center -of -Mass det. time= 255.2 min ( 1,035.2 - 780.0 ) Proposed Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description Type III 24 -hr 2 -year Rainfall=3.10" Printed 11/7/2013 Page 10 #1 24.00' 3,238 cf #2 24.50' 5,168 cf 40.00W x 103.00'L x 3.50'H Crushed Stone 14,420 cf Overall - 5,168 cf Embedded = 9,252 cf x 35.0% Voids ADS_StormTech SC -740 x 112 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 8 rows Device Routing 8,406 cf Total Available Storage Invert Outlet Devices #1 Primary 24.50' 18.0" Round Culvert L= 23.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 24.50' / 24.27' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 1.77 sf #2 Device 1 26.75' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 #3 Discarded 24.00' 2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.23 cfs @ 10.63 hrs HW=24.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.23 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=24.00' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) L2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond 2P: INFILTRATION BASIN 2 [79] Warning: Submerged Pond 5P Primary device # 1 OUTLET by 0.18' Inflow Area = Inflow = Outflow = Discarded = Primary = 4.270 ac, 80.09% Impervious, Inflow Depth = 1.88" for 2 -year event 8.72 cfs @ 12.07 hrs, Volume= 0.61 cfs @ 11.11 hrs, Volume= 0.61 cfs @ 11.11 hrs, Volume= 0.00 cfs @ 0.00 hrs, Volume= 0.669 af 0.669 af, Atten= 93%, Lag= 0.0 min 0.669 af 0.000 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 27.56' @ 13.21 hrs Surf.Area= 10,870 sf Storage= 11,244 cf Flood Elev= 29.50' Surf.Area= 10,870 sf Storage= 22,567 cf Plug -Flow detention time= 140.0 min calculated for 0.669 of (100% of inflow) Center -of -Mass det. time= 140.0 min ( 896.2 - 756.1 ) Volume Invert Avail.Storage Storage Description #1 26.00' 8,334 cf Crushed Stone (Prismatic)Listed below (Recalc) 38,045 cf Overall - 14,232 cf Embedded = 23,813 cf x 35.0% Voids #2 26.50' 8,702 cf ADS_StormTech SC -740 x 189 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 7 rows #3 26.50' 5,530 cf ADS_StormTech SC -740 x 120 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Proposed Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Type III 24 -hr 2 -year Rainfall=3.10" Printed 11/7/2013 Page 11 Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 6 rows Elevation (feet) 26.00 29.50 Surf.Area (sq-ft) 10,870 10,870 22,567 cf Total Available Storage Inc.Store (cubic -feet) 0 38,045 Device Routing Invert Outlet Devices Cum.Store (cubic -feet) 0 38,045 #1 #2 Device 1 #3 Primary 26.50' 24.0" Round Culvert L= 8.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 26.50' / 26.40' S= 0.0125 '/' Cc= 0.900 n= 0.012, Flow Area= 3.14 sf 28.40' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 Discarded 26.00' 2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.61 cfs @ 11.11 hrs HW=26.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.61 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=26.00' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) L2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Inflow Area = Inflow = Outflow = Discarded = Primary = Summary for Pond 3P: INFILTRATION BASIN 3 0.850 ac, 82.35% Impervious, Inflow Depth = 2.45" for 2 -year event 2.43 cfs @ 12.07 hrs, Volume= 0.173 af 0.12 cfs @ 10.67 hrs, Volume= 0.173 af, Atten= 95%, Lag= 0.0 min 0.12 cfs @ 10.67 hrs, Volume= 0.173 of 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 28.67' @ 14.35 hrs Surf.Area= 2,091 sf Storage= 3,597 cf Flood Elev= 29.50' Surf.Area= 2,091 sf Storage= 4,241 cf Plug -Flow detention time= 275.7 min calculated for 0.173 af (100% of inflow) Center -of -Mass det. time= 275.7 min ( 1,063.0 - 787.2 ) Volume #1 #2 Invert Avail.Storaae Storage Description 26.00' 1,657 cf 20.50'W x 102.00'L x 3.50'H Crushed Stone 7,319 cf Overall - 2,584 cf Embedded = 4,735 cf x 35.0% Voids 26.50' 2,584 cf ADS_StormTech SC -740 x 56 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 4 rows 4,241 cf Total Available Storage Proposed Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Device Routing Invert Outlet Devices Type III 24 -hr 2 -year Rainfall=3.10" Printed 11/7/2013 Page 12 #1 Primary 26.50' 15.0" Round Culvert L= 25.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 26.50' / 26.25' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 1.23 sf #2 Device 1 29.00' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 #3 Discarded 26.00' 2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.12 cfs @ 10.67 hrs HW=26.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.12 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=26.00' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) L2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Inflow Area = Inflow = Outflow = Discarded = Primary = Summary for Pond 4P: INFILTRATION BASIN 4 0.350 ac, 85.71% Impervious, Inflow Depth = 2.55" for 2 -year event 1.03 cfs @ 12.07 hrs, Volume= 0.074 af 0.03 cfs @ 9.43 hrs, Volume= 0.074 af, Atten= 97%, Lag= 0.0 min 0.03 cfs @ 9.43 hrs, Volume= 0.074 af 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 26.44' @ 16.00 hrs Surf.Area= 1,210 sf Storage= 1,919 cf Flood Elev= 27.50' Surf.Area= 1,210 sf Storage= 2,445 cf Plug -Flow detention time= 612.4 min calculated for 0.074 af (100% of inflow) Center -of -Mass det. time= 612.4 min ( 1,393.4 - 781.0 ) Volume Invert Avail.Storage Storage Description #1 24.00' 963 cf #2 24.50' 1,481 cf 20.50'W x 59.00'L x 3.50'H Crushed Stone 4,233 cf Overall - 1,481 cf Embedded = 2,752 cf x 35.0% Voids ADS_StormTech SC -740 x 32 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 4 rows 2,445 cf Device Routing Invert Total Available Storage Outlet Devices #1 Primary #2 Device 1 #3 Discarded 24.50' 12.0" Round Culvert L= 85.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 24.50' / 23.65' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 0.79 sf 27.20' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 24.00' 1.020 in/hr Exfiltration over Surface area Proposed Watershed Type III 24 -hr 2 -year Rainfall=3.10" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 13 Discarded OutFlow Max=0.03 cfs @ 9.43 hrs HW=24.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=24.00' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) L2=Broad-Crested Rectangular Weir( Controls 0.00 cfs) Summary for Pond 5P: RAIN GARGEN Inflow Area = 1.470 ac, 42.18% Impervious, Inflow Depth = 1.68" for 2 -year event Inflow = 2.91 cfs @ 12.07 hrs, Volume= 0.206 af Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 100%, Lag= 0.0 min Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 27.82' @ 24.29 hrs Surf.Area= 11,479 sf Storage= 8,961 cf Plug -Flow detention time= (not calculated: initial storage excedes outflow) Center -of -Mass det. time= (not calculated: no outflow) Volume Invert Avail.Storage Storage Description #1 27.00' 23,450 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 27.00 10,500 0 0 28.00 11,700 11,100 11,100 29.00 13,000 12,350 23,450 Device Routing Invert Outlet Devices #1 Primary 28.75' 12.0" Round Culvert L= 66.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 28.75' / 27.38' S= 0.0208 '/' Cc= 0.900 n= 0.013, Flow Area= 0.79 sf Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=27.00' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) Proposed Watershed Type III 24 -hr 10 -year Rainfall=4.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 14 Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1AS: Subcatchment 1 BS: COURTYARD Subcatchment 1S: Subcatchment2AS: ROOF Subcatchment2BS: GARAGE Subcatchment2CS: Subcatchment2DS: COURTYARD Subcatchment 3S: ROOF Subcatchment4S: Subcatchment 5S: Subcatchment 6S: Subcatchment 7S: Reach 1R: DESIGN POINT 1 Reach 2R: DESIGN POINT 2 Runoff Area=1.330 ac 85.71% Impervious Runoff Depth=3.92" Tc=5.0 min CN=95 Runoff=5.86 cfs 0.435 af Runoff Area=0.230 ac 91.30% Impervious Runoff Depth=4.04" Tc=5.0 min CN=96 Runoff=1.03 cfs 0.077 af Runoff Area=0.140 ac 28.57% Impervious Runoff Depth=2.55" Tc=5.0 min CN=81 Runoff=0.43 cfs 0.030 af Runoff Area=2.060 ac 100.00% Impervious Runoff Depth=4.26" Tc=5.0 min CN=98 Runoff=9.38 cfs 0.732 af Runoff Area=0.740 ac 100.00% Impervious Runoff Depth=4.26" Tc=5.0 min CN=98 Runoff=3.37 cfs 0.263 af Runoff Area=0.640 ac 57.81% Impervious Runoff Depth=3.20" Tc=5.0 min CN=88 Runoff=2.44 cfs 0.170 af Runoff Area=0.280 ac 89.29% Impervious Runoff Depth=3.92" Tc=5.0 min CN=95 Runoff=1.23 cfs 0.092 af Runoff Area=0.850 ac 82.35% Impervious Runoff Depth=3.82" Tc=5.0 min CN=94 Runoff=3.69 cfs 0.270 af Runoff Area=0.350 ac 85.71% Impervious Runoff Depth=3.92" Tc=5.0 min CN=95 Runoff=1.54 cfs 0.114 of Runoff Area=0.550 ac 0.00% Impervious Runoff Depth=1.97" Tc=5.0 min CN=74 Runoff=1.31 cfs 0.090 af Runoff Area=0.550 ac 74.55% Impervious Runoff Depth=3.60" Tc=5.0 min CN=92 Runoff=2.30 cfs 0.165 af Runoff Area=0.280 ac 0.00% Impervious Runoff Depth=1.97" Tc=5.0 min CN=74 Runoff=0.66 cfs 0.046 af Inflow=0.43 cfs 0.030 af Outflow=0.43 cfs 0.030 af Inflow=5.67 cfs 0.451 af Outflow=5.67 cfs 0.451 af Pond 1P: INFILTRATION BASIN 1 Peak Elev=27.08' Storage=7,798 cf Inflow=6.89 cfs 0.512 af Discarded=0.23 cfs 0.401 af Primary=2.71 cfs 0.111 af Outflow=2.94 cfs 0.512 af Pond 2P: INFILTRATION BASIN 2 Peak EIev=28.51' Storage=18,232 cf Inflow=12.75 cfs 0.995 af Discarded=0.61 cfs 0.952 af Primary=0.50 cfs 0.043 af Outflow=1.10 cfs 0.995 af Proposed Watershed Type III 24 -hr 10 -year Rainfall=4.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 15 Pond 3P: INFILTRATION BASIN 3 Peak Elev=29.24' Storage=4,050 cf Inflow=3.69 cfs 0.270 af Discarded=0.12 cfs 0.208 af Primary=1.66 cfs 0.062 af Outflow=1.77 cfs 0.270 af Pond 4P: INFILTRATION BASIN 4 Peak EIev=27.30' Storage=2,359 cf Inflow=1.54 cfs 0.114 af Discarded=0.03 cfs 0.091 af Primary=0.42 cfs 0.024 af Outflow=0.45 cfs 0.114 af Pond 5P: RAIN GARGEN Peak EIev=28.36' Storage=15,352 cf Inflow=4.98 cfs 0.352 af 12.0" Round Culvert n=0.013 L=66.0' S=0.0208 '/' Outflow=0.00 cfs 0.000 af Total Runoff Area = 8.000 ac Runoff Volume = 2.485 af Average Runoff Depth = 3.73" 22.25% Pervious = 1.780 ac 77.75% Impervious = 6.220 ac Proposed Watershed Type III 24 -hr 10 -year Rainfall=4.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 16 Summary for Subcatchment lAS: Runoff = 5.86 cfs @ 12.07 hrs, Volume= 0.435 af, Depth= 3.92" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description 1.140 98 Pavement 0.190 74 >75% Grass cover, Good, HSG C 1.330 95 Weighted Average 0.190 14.29% Pervious Area 1.140 85.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 1 BS: COURTYARD Runoff = 1.03 cfs © 12.07 hrs, Volume= 0.077 af, Depth= 4.04" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description 0.210 98 Pavement 0.020 74 >75% Grass cover, Good, HSG C 0.230 96 Weighted Average 0.020 8.70% Pervious Area 0.210 91.30% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 1S: Runoff = 0.43 cfs @ 12.07 hrs, Volume= 0.030 af, Depth= 2.55" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description 0.040 98 Pavement 0.100 74 >75% Grass cover, Good, HSG C 0.140 81 Weighted Average 0.100 71.43% Pervious Area 0.040 28.57% Impervious Area Proposed Watershed Type III 24 -hr 10 -year Rainfall=4.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 17 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2AS: ROOF Runoff = 9.38 cfs @ 12.07 hrs, Volume= 0.732 af, Depth= 4.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description * 2.060 98 Roof 2.060 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2BS: GARAGE Runoff = 3.37 cfs @ 12.07 hrs, Volume= 0.263 af, Depth= 4.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description 0.740 98 Roof 0.740 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Runoff Summary for Subcatchment 2CS: = 2.44 cfs @ 12.07 hrs, Volume= 0.170 af, Depth= 3.20" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description 0.370 98 Pavement 0.270 74 >75% Grass cover, Good, HSG C 0.640 88 Weighted Average 0.270 42.19% Pervious Area 0.370 57.81% Impervious Area Proposed Watershed Type III 24 -hr 10 -year Rainfall=4.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 18 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2DS: COURTYARD Runoff = 1.23 cfs @ 12.07 hrs, Volume= 0.092 af, Depth= 3.92" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description * 0.250 98 Pavement 0.030 74 >75% Grass cover, Good, HSG C 0.280 95 Weighted Average 0.030 10.71% Pervious Area 0.250 89.29% Impervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 3S: ROOF Runoff = 3.69 cfs @ 12.07 hrs, Volume= 0.270 af, Depth= 3.82" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description 0.700 98 Pavement 0.150 74 >75% Grass cover, Good, HSG C 0.850 94 Weighted Average 0.150 17.65% Pervious Area 0.700 82.35% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 4S: Runoff = 1.54 cfs @ 12.07 hrs, Volume= 0.114 af, Depth= 3.92" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Proposed Watershed Type III 24 -hr 10 -year Rainfall=4.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 19 Area (ac) CN Description 0.300 98 Pavement 0.050 74 >75% Grass cover, Good, HSG C 0.350 95 Weighted Average 0.050 14.29% Pervious Area 0.300 85.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 5S: Runoff = 1.31 cfs @ 12.08 hrs, Volume= 0.090 af, Depth= 1.97" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description 0.550 74 >75% Grass cover, Good, HSG C 0.550 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 6S: Runoff = 2.30 cfs @ 12.07 hrs, Volume= 0.165 af, Depth= 3.60" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description 0.410 98 Pavement 0.140 74 >75% Grass cover, Good, HSG C 0.550 92 Weighted Average 0.140 25.45% Pervious Area 0.410 74.55% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Proposed Watershed Type III 24 -hr 10 -year Rainfall=4.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 20 Summary for Subcatchment 7S: Runoff = 0.66 cfs @ 12.08 hrs, Volume= 0.046 af, Depth= 1.97" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 10 -year Rainfall=4.50" Area (ac) CN Description 0.280 74 >75% Grass cover, Good, HSG C 0.280 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Reach 1R: DESIGN POINT 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.140 ac, 28.57% Impervious, Inflow Depth = 2.55" for 10 -year event Inflow = 0.43 cfs @ 12.07 hrs, Volume= 0.030 af Outflow = 0.43 cfs @ 12.07 hrs, Volume= 0.030 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Summary for Reach 2R: DESIGN POINT 2 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 7.860 ac, 78.63% Impervious, Inflow Depth = 0.69" for 10 -year event Inflow = 5.67 cfs @ 12.22 hrs, Volume= 0.451 af Outflow = 5.67 cfs @ 12.22 hrs, Volume= 0.451 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Summary for Pond 1P: INFILTRATION BASIN 1 Inflow Area = 1.560 ac, 86.54% Impervious, Inflow Depth = 3.94" for 10 -year event Inflow = 6.89 cfs @ 12.07 hrs, Volume= 0.512 af Outflow = 2.94 cfs @ 12.24 hrs, Volume= 0.512 af, Atten= 57%, Lag= 10.3 min Discarded = 0.23 cfs @ 9.45 hrs, Volume= 0.401 af Primary = 2.71 cfs @ 12.24 hrs, Volume= 0.111 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 27.08' @ 12.24 hrs Surf.Area= 4,120 sf Storage= 7,798 cf Flood Elev= 27.50' Surf.Area= 4,120 sf Storage= 8,406 cf Plug -Flow detention time= 226.3 min calculated for 0.512 af (100% of inflow) Center -of -Mass det. time= 226.3 min ( 995.5 - 769.2 ) Proposed Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description Type III 24 -hr 10 -year Rainfall=4.50" Printed 11/7/2013 Page 21 #1 24.00' 3,238 cf #2 24.50' 5,168 cf 40.00W x 103.00'L x 3.50'H Crushed Stone 14,420 cf Overall - 5,168 cf Embedded = 9,252 cf x 35.0% Voids ADS_StormTech SC -740 x 112 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 8 rows Device Routing 8,406 cf Total Available Storage Invert Outlet Devices #1 Primary 24.50' 18.0" Round Culvert L= 23.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 24.50' / 24.27' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 1.77 sf #2 Device 1 26.75' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 #3 Discarded 24.00' 2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.23 cfs @ 9.45 hrs HW=24.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.23 cfs) Primary OutFlow Max=2.71 cfs @ 12.24 hrs HW=27.08' (Free Discharge) L1=Culvert (Passes 2.71 cfs of 11.50 cfs potential flow) L2=Broad-Crested Rectangular Weir (Weir Controls 2.71 cfs @ 1.65 fps) Summary for Pond 2P: INFILTRATION BASIN 2 [79] Warning: Submerged Pond 5P Primary device # 1 OUTLET by 1.13' Inflow Area = Inflow = Outflow = Discarded = Primary = 4.270 ac, 80.09% Impervious, Inflow Depth = 2.80" for 10 -year event 12.75 cfs @ 12.07 hrs, Volume= 1.10 cfs @ 12.92 hrs, Volume= 0.61 cfs @ 10.16 hrs, Volume= 0.50 cfs @ 12.92 hrs, Volume= 0.995 af 0.995 af, Allen= 91°A, Lag= 51.2 min 0.952 af 0.043 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 28.51' @ 12.92 hrs Surf.Area= 10,870 sf Storage= 18,232 cf Flood Elev= 29.50' Surf.Area= 10,870 sf Storage= 22,567 cf Plug -Flow detention time= 229.5 min calculated for 0.995 af (100% of inflow) Center -of -Mass det. time= 229.5 min ( 978.4 - 748.9 ) Volume Invert Avail.Storage Storage Description #1 26.00' 8,334 cf Crushed Stone (Prismatic)Listed below (Recalc) 38,045 cf Overall - 14,232 cf Embedded = 23,813 cf x 35.0% Voids #2 26.50' 8,702 cf ADS_StormTech SC -740 x 189 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 7 rows #3 26.50' 5,530 cf ADS_StormTech SC -740 x 120 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Proposed Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Type III 24 -hr 10 -year Rainfall=4.50" Printed 11/7/2013 Page 22 Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 6 rows Elevation (feet) 26.00 29.50 Surf.Area (sq-ft) 10,870 10,870 22,567 cf Total Available Storage Inc.Store (cubic -feet) 0 38,045 Device Routing Invert Outlet Devices Cum.Store (cubic -feet) 0 38,045 #1 #2 Device 1 #3 Primary 26.50' 24.0" Round Culvert L= 8.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 26.50' / 26.40' S= 0.0125 '/' Cc= 0.900 n= 0.012, Flow Area= 3.14 sf 28.40' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 Discarded 26.00' 2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.61 cfs @ 10.16 hrs HW=26.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.61 cfs) Primary OutFlow Max=0.50 cfs @ 12.92 hrs HW=28.51' (Free Discharge) L1=Culvert (Passes 0.50 cfs of 12.62 cfs potential flow) L2=Broad-Crested Rectangular Weir (Weir Controls 0.50 cfs @ 0.92 fps) Inflow Area = Inflow = Outflow = Discarded = Primary = Summary for Pond 3P: INFILTRATION BASIN 3 0.850 ac, 82.35% Impervious, Inflow Depth = 3.82" for 10 -year event 3.69 cfs @ 12.07 hrs, Volume= 0.270 af 1.77 cfs @ 12.21 hrs, Volume= 0.270 af, Atten= 52%, Lag= 8.2 min 0.12 cfs @ 9.49 hrs, Volume= 0.208 af 1.66 cfs @ 12.21 hrs, Volume= 0.062 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 29.24' @ 12.21 hrs Surf.Area= 2,091 sf Storage= 4,050 cf Flood Elev= 29.50' Surf.Area= 2,091 sf Storage= 4,241 cf Plug -Flow detention time= 237.6 min calculated for 0.270 af (100% of inflow) Center -of -Mass det. time= 237.7 min ( 1,013.2 - 775.6 ) Volume #1 #2 Invert Avail.Storaae Storage Description 26.00' 1,657 cf 20.50'W x 102.00'L x 3.50'H Crushed Stone 7,319 cf Overall - 2,584 cf Embedded = 4,735 cf x 35.0% Voids 26.50' 2,584 cf ADS_StormTech SC -740 x 56 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 4 rows 4,241 cf Total Available Storage Proposed Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Device Routing Invert Outlet Devices Type III 24 -hr 10 -year Rainfall=4.50" Printed 11/7/2013 Page 23 #1 Primary #2 Device 1 #3 Discarded 26.50' 15.0" Round Culvert L= 25.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 26.50' / 26.25' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 1.23 sf 29.00' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 26.00' 2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.12 cfs @ 9.49 hrs HW=26.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.12 cfs) Primary OutFlow Max=1.65 cfs @ 12.21 hrs HW=29.24' (Free Discharge) L1=Culvert (Passes 1.65 cfs of 8.59 cfs potential flow) L2=Broad-Crested Rectangular Weir (Weir Controls 1.65 cfs @ 1.38 fps) Inflow Area = Inflow = Outflow = Discarded = Primary = Summary for Pond 4P: INFILTRATION BASIN 4 0.350 ac, 85.71% Impervious, Inflow Depth = 3.92" for 10 -year event 1.54 cfs @ 12.07 hrs, Volume= 0.114 af 0.45 cfs @ 12.38 hrs, Volume= 0.114 af, Atten= 71%, Lag= 18.7 min 0.03 cfs @ 8.22 hrs, Volume= 0.091 af 0.42 cfs @ 12.38 hrs, Volume= 0.024 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 27.30' @ 12.38 hrs Surf.Area= 1,210 sf Storage= 2,359 cf Flood Elev= 27.50' Surf.Area= 1,210 sf Storage= 2,445 cf Plug -Flow detention time= 599.4 min calculated for 0.114 af (100% of inflow) Center -of -Mass det. time= 599.4 min ( 1,369.5 - 770.1 ) Volume Invert Avail.Storage Storage Description #1 24.00' 963 cf #2 24.50' 1,481 cf 20.50'W x 59.00'L x 3.50'H Crushed Stone 4,233 cf Overall - 1,481 cf Embedded = 2,752 cf x 35.0% Voids ADS_StormTech SC -740 x 32 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 4 rows Device Routing 2,445 cf Total Available Storage Invert Outlet Devices #1 Primary #2 Device 1 #3 Discarded 24.50' 12.0" Round Culvert L= 85.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 24.50' / 23.65' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 0.79 sf 27.20' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 24.00' 1.020 in/hr Exfiltration over Surface area Proposed Watershed Type III 24 -hr 10 -year Rainfall=4.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 24 Discarded OutFlow Max=0.03 cfs @ 8.22 hrs HW=24.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=0.42 cfs @ 12.38 hrs HW=27.30' (Free Discharge) L1=Culvert (Passes 0.42 cfs of 5.28 cfs potential flow) L2=Broad-Crested Rectangular Weir (Weir Controls 0.42 cfs @ 0.87 fps) Summary for Pond 5P: RAIN GARGEN Inflow Area = 1.470 ac, 42.18% Impervious, Inflow Depth = 2.88" for 10 -year event Inflow = 4.98 cfs @ 12.07 hrs, Volume= 0.352 af Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 100%, Lag= 0.0 min Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 28.36' @ 24.29 hrs Surf.Area= 12,163 sf Storage= 15,352 cf Plug -Flow detention time= (not calculated: initial storage excedes outflow) Center -of -Mass det. time= (not calculated: no outflow) Volume Invert Avail.Storage Storage Description #1 27.00' 23,450 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 27.00 10,500 0 0 28.00 11,700 11,100 11,100 29.00 13,000 12,350 23,450 Device Routing Invert Outlet Devices #1 Primary 28.75' 12.0" Round Culvert L= 66.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 28.75' / 27.38' S= 0.0208 '/' Cc= 0.900 n= 0.013, Flow Area= 0.79 sf Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=27.00' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) Proposed Watershed Type III 24 -hr 25 -year Rainfall=5.30" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 25 Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1AS: Subcatchment 1 BS: COURTYARD Subcatchment 1S: Subcatchment2AS: ROOF Subcatchment2BS: GARAGE Subcatchment2CS: Subcatchment2DS: COURTYARD Subcatchment 3S: ROOF Subcatchment4S: Subcatchment 5S: Subcatchment 6S: Subcatchment 7S: Reach 1R: DESIGN POINT 1 Reach 2R: DESIGN POINT 2 Runoff Area=1.330 ac 85.71% Impervious Runoff Depth=4.72" Tc=5.0 min CN=95 Runoff=6.97 cfs 0.523 af Runoff Area=0.230 ac 91.30% Impervious Runoff Depth=4.83" Tc=5.0 min CN=96 Runoff=1.22 cfs 0.093 af Runoff Area=0.140 ac 28.57% Impervious Runoff Depth=3.25" Tc=5.0 min CN=81 Runoff=0.55 cfs 0.038 af Runoff Area=2.060 ac 100.00% Impervious Runoff Depth=5.06" Tc=5.0 min CN=98 Runoff=11.07 cfs 0.869 af Runoff Area=0.740 ac 100.00% Impervious Runoff Depth=5.06" Tc=5.0 min CN=98 Runoff=3.98 cfs 0.312 af Runoff Area=0.640 ac 57.81% Impervious Runoff Depth=3.95" Tc=5.0 min CN=88 Runoff=2.99 cfs 0.211 af Runoff Area=0.280 ac 89.29% Impervious Runoff Depth=4.72" Tc=5.0 min CN=95 Runoff=1.47 cfs 0.110 af Runoff Area=0.850 ac 82.35% Impervious Runoff Depth=4.60" Tc=5.0 min CN=94 Runoff=4.40 cfs 0.326 af Runoff Area=0.350 ac 85.71% Impervious Runoff Depth=4.72" Tc=5.0 min CN=95 Runoff=1.83 cfs 0.138 af Runoff Area=0.550 ac 0.00% Impervious Runoff Depth=2.61" Tc=5.0 min CN=74 Runoff=1.74 cfs 0.119 of Runoff Area=0.550 ac 74.55% Impervious Runoff Depth=4.38" Tc=5.0 min CN=92 Runoff=2.77 cfs 0.201 af Runoff Area=0.280 ac 0.00% Impervious Runoff Depth=2.61" Tc=5.0 min CN=74 Runoff=0.88 cfs 0.061 af Inflow=0.55 cfs 0.038 af Outflow=0.55 cfs 0.038 af Inflow=12.42 cfs 0.766 af Outflow=12.42 cfs 0.766 af Pond 1P: INFILTRATION BASIN 1 Peak Elev=27.29' Storage=8,098 cf Inflow=8.19 cfs 0.615 af Discarded=0.23 cfs 0.426 af Primary=5.95 cfs 0.189 af Outflow=6.18 cfs 0.615 af Pond 2P: INFILTRATION BASIN 2 Peak Elev=28.75' Storage=19,619 cf Inflow=15.05 cfs 1.181 af Discarded=0.61 cfs 1.015 af Primary=3.04 cfs 0.166 af Outflow=3.65 cfs 1.181 af Proposed Watershed Type III 24 -hr 25 -year Rainfall=5.30" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 26 Pond 3P: INFILTRATION BASIN 3 Peak Elev=29.40' Storage=4,165 cf Inflow=4.40 cfs 0.326 af Discarded=0.12 cfs 0.221 af Primary=3.64 cfs 0.105 af Outflow=3.75 cfs 0.326 af Pond 4P: INFILTRATION BASIN 4 Peak EIev=27.37' Storage=2,391 cf Inflow=1.83 cfs 0.138 af Discarded=0.03 cfs 0.094 af Primary=1.01 cfs 0.043 af Outflow=1.04 cfs 0.138 af Pond 5P: RAIN GARGEN Peak EIev=28.67' Storage=19,184 cf Inflow=6.20 cfs 0.440 af 12.0" Round Culvert n=0.013 L=66.0' S=0.0208 '/' Outflow=0.00 cfs 0.000 af Total Runoff Area = 8.000 ac Runoff Volume = 3.000 af Average Runoff Depth = 4.50" 22.25% Pervious = 1.780 ac 77.75% Impervious = 6.220 ac Proposed Watershed Type III 24 -hr 25 -year Rainfall=5.30" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 27 Summary for Subcatchment lAS: Runoff = 6.97 cfs @ 12.07 hrs, Volume= 0.523 af, Depth= 4.72" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description 1.140 98 Pavement 0.190 74 >75% Grass cover, Good, HSG C 1.330 95 Weighted Average 0.190 14.29% Pervious Area 1.140 85.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 1 BS: COURTYARD Runoff = 1.22 cfs © 12.07 hrs, Volume= 0.093 af, Depth= 4.83" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description 0.210 98 Pavement 0.020 74 >75% Grass cover, Good, HSG C 0.230 96 Weighted Average 0.020 8.70% Pervious Area 0.210 91.30% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 1S: Runoff = 0.55 cfs @ 12.07 hrs, Volume= 0.038 af, Depth= 3.25" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description 0.040 98 Pavement 0.100 74 >75% Grass cover, Good, HSG C 0.140 81 Weighted Average 0.100 71.43% Pervious Area 0.040 28.57% Impervious Area Proposed Watershed Type III 24 -hr 25 -year Rainfall=5.30" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 28 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2AS: ROOF Runoff = 11.07 cfs @ 12.07 hrs, Volume= 0.869 af, Depth= 5.06" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description * 2.060 98 Roof 2.060 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2BS: GARAGE Runoff = 3.98 cfs © 12.07 hrs, Volume= 0.312 af, Depth= 5.06" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description 0.740 98 Roof 0.740 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2CS: Runoff = 2.99 cfs @ 12.07 hrs, Volume= 0.211 af, Depth= 3.95" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description 0.370 98 Pavement 0.270 74 >75% Grass cover, Good, HSG C 0.640 88 Weighted Average 0.270 42.19% Pervious Area 0.370 57.81% Impervious Area Proposed Watershed Type III 24 -hr 25 -year Rainfall=5.30" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 29 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2DS: COURTYARD Runoff = 1.47 cfs @ 12.07 hrs, Volume= 0.110 af, Depth= 4.72" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description * 0.250 98 Pavement 0.030 74 >75% Grass cover, Good, HSG C 0.280 95 Weighted Average 0.030 10.71% Pervious Area 0.250 89.29% Impervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 3S: ROOF Runoff = 4.40 cfs @ 12.07 hrs, Volume= 0.326 af, Depth= 4.60" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description 0.700 98 Pavement 0.150 74 >75% Grass cover, Good, HSG C 0.850 94 Weighted Average 0.150 17.65% Pervious Area 0.700 82.35% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 4S: Runoff = 1.83 cfs @ 12.07 hrs, Volume= 0.138 af, Depth= 4.72" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Proposed Watershed Type III 24 -hr 25 -year Rainfall=5.30" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 30 Area (ac) CN Description 0.300 98 Pavement 0.050 74 >75% Grass cover, Good, HSG C 0.350 95 Weighted Average 0.050 14.29% Pervious Area 0.300 85.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 5S: Runoff = 1.74 cfs @ 12.08 hrs, Volume= 0.119 af, Depth= 2.61" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description 0.550 74 >75% Grass cover, Good, HSG C 0.550 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Runoff Direct Entry, Summary for Subcatchment 6S: = 2.77 cfs @ 12.07 hrs, Volume= 0.201 af, Depth= 4.38" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description 0.410 98 Pavement 0.140 74 >75% Grass cover, Good, HSG C 0.550 92 Weighted Average 0.140 25.45% Pervious Area 0.410 74.55% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Proposed Watershed Type III 24 -hr 25 -year Rainfall=5.30" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 31 Summary for Subcatchment 7S: Runoff = 0.88 cfs @ 12.08 hrs, Volume= 0.061 af, Depth= 2.61" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 25 -year Rainfall=5.30" Area (ac) CN Description 0.280 74 >75% Grass cover, Good, HSG C 0.280 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Reach 1R: DESIGN POINT 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.140 ac, 28.57% Impervious, Inflow Depth = 3.25" for 25 -year event Inflow = 0.55 cfs @ 12.07 hrs, Volume= 0.038 af Outflow = 0.55 cfs @ 12.07 hrs, Volume= 0.038 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Summary for Reach 2R: DESIGN POINT 2 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 7.860 ac, 78.63% Impervious, Inflow Depth = 1.17" for 25 -year event Inflow = 12.42 cfs @ 12.12 hrs, Volume= 0.766 of Outflow = 12.42 cfs @ 12.12 hrs, Volume= 0.766 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Summary for Pond 1P: INFILTRATION BASIN 1 Inflow Area = 1.560 ac, 86.54% Impervious, Inflow Depth = 4.73" for 25 -year event Inflow = 8.19 cfs @ 12.07 hrs, Volume= 0.615 of Outflow = 6.18 cfs @ 12.13 hrs, Volume= 0.615 af, Atten= 25%, Lag= 3.9 min Discarded = 0.23 cfs @ 8.89 hrs, Volume= 0.426 af Primary = 5.95 cfs @ 12.13 hrs, Volume= 0.189 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 27.29' @ 12.13 hrs Surf.Area= 4,120 sf Storage= 8,098 cf Flood Elev= 27.50' Surf.Area= 4,120 sf Storage= 8,406 cf Plug -Flow detention time= 204.0 min calculated for 0.615 af (100% of inflow) Center -of -Mass det. time= 204.0 min ( 968.9 - 764.9 ) Proposed Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description Type III 24 -hr 25 -year Rainfall=5.30" Printed 11/7/2013 Page 32 #1 24.00' 3,238 cf #2 24.50' 5,168 cf 40.00W x 103.00'L x 3.50'H Crushed Stone 14,420 cf Overall - 5,168 cf Embedded = 9,252 cf x 35.0% Voids ADS_StormTech SC -740 x 112 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 8 rows Device Routing 8,406 cf Total Available Storage Invert Outlet Devices #1 Primary #2 Device 1 #3 Discarded 24.50' 18.0" Round Culvert L= 23.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 24.50' / 24.27' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 1.77 sf 26.75' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 24.00' 2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.23 cfs @ 8.89 hrs HW=24.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.23 cfs) Primary OutFlow Max=5.91 cfs @ 12.13 hrs HW=27.28' (Free Discharge) L1=Culvert (Passes 5.91 cfs of 12.14 cfs potential flow) L2=Broad-Crested Rectangular Weir (Weir Controls 5.91 cfs @ 2.21 fps) Summary for Pond 2P: INFILTRATION BASIN 2 [81] Warning: Exceeded Pond 5P by 0.76' @ 12.41 hrs Inflow Area = Inflow = Outflow = Discarded = Primary = 4.270 ac, 80.09% Impervious, Inflow Depth = 3.32" for 25 -year event 15.05 cfs @ 12.07 hrs, Volume= 1.181 af 3.65 cfs @ 12.43 hrs, Volume= 1.181 af, Allen= 76%, Lag= 21.9 min 0.61 cfs @ 9.55 hrs, Volume= 1.015 af 3.04 cfs @ 12.43 hrs, Volume= 0.166 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 28.75' @ 12.43 hrs Surf.Area= 10,870 sf Storage= 19,619 cf Flood Elev= 29.50' Surf.Area= 10,870 sf Storage= 22,567 cf Plug -Flow detention time= 211.0 min calculated for 1.181 af (100% of inflow) Center -of -Mass det. time= 211.0 min ( 957.1 - 746.1 ) Volume Invert Avail.Storage Storage Description #1 26.00' 8,334 cf Crushed Stone (Prismatic)Listed below (Recalc) 38,045 cf Overall - 14,232 cf Embedded = 23,813 cf x 35.0% Voids #2 26.50' 8,702 cf ADS_StormTech SC -740 x 189 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 7 rows #3 26.50' 5,530 cf ADS_StormTech SC -740 x 120 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Proposed Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Type III 24 -hr 25 -year Rainfall=5.30" Printed 11/7/2013 Page 33 Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 6 rows Elevation (feet) 26.00 29.50 Surf.Area (sq-ft) 10,870 10,870 22,567 cf Total Available Storage Inc.Store (cubic -feet) 0 38,045 Device Routing Invert Outlet Devices Cum.Store (cubic -feet) 0 38,045 #1 #2 Device 1 #3 Primary 26.50' 24.0" Round Culvert L= 8.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 26.50' / 26.40' S= 0.0125 '/' Cc= 0.900 n= 0.012, Flow Area= 3.14 sf 28.40' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 Discarded 26.00' 2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.61 cfs @ 9.55 hrs HW=26.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.61 cfs) Primary OutFlow Max=3.04 cfs @ 12.43 hrs HW=28.75' (Free Discharge) L1=Culvert (Passes 3.04 cfs of 14.79 cfs potential flow) L2=Broad-Crested Rectangular Weir (Weir Controls 3.04 cfs @ 1.72 fps) Inflow Area = Inflow = Outflow = Discarded = Primary = Summary for Pond 3P: INFILTRATION BASIN 3 0.850 ac, 82.35% Impervious, Inflow Depth = 4.60" for 25 -year event 4.40 cfs @ 12.07 hrs, Volume= 0.326 af 3.75 cfs @ 12.12 hrs, Volume= 0.326 af, Atten= 15%, Lag= 2.8 min 0.12 cfs @ 8.92 hrs, Volume= 0.221 af 3.64 cfs @ 12.12 hrs, Volume= 0.105 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 29.40' @ 12.12 hrs Surf.Area= 2,091 sf Storage= 4,165 cf Flood Elev= 29.50' Surf.Area= 2,091 sf Storage= 4,241 cf Plug -Flow detention time= 213.0 min calculated for 0.326 af (100% of inflow) Center -of -Mass det. time= 213.0 min ( 983.9 - 770.9 ) Volume #1 #2 Invert Avail.Storaae Storage Description 26.00' 1,657 cf 20.50'W x 102.00'L x 3.50'H Crushed Stone 7,319 cf Overall - 2,584 cf Embedded = 4,735 cf x 35.0% Voids 26.50' 2,584 cf ADS_StormTech SC -740 x 56 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 4 rows 4,241 cf Total Available Storage Proposed Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Device Routing Invert Outlet Devices Type III 24 -hr 25 -year Rainfall=5.30" Printed 11/7/2013 Page 34 #1 Primary #2 Device 1 #3 Discarded 26.50' 15.0" Round Culvert L= 25.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 26.50' / 26.25' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 1.23 sf 29.00' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 26.00' 2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.12 cfs @ 8.92 hrs HW=26.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.12 cfs) Primary OutFlow Max=3.62 cfs @ 12.12 hrs HW=29.40' (Free Discharge) L1=Culvert (Passes 3.62 cfs of 8.90 cfs potential flow) L2=Broad-Crested Rectangular Weir (Weir Controls 3.62 cfs @ 1.83 fps) Inflow Area = Inflow = Outflow = Discarded = Primary = Summary for Pond 4P: INFILTRATION BASIN 4 0.350 ac, 85.71% Impervious, Inflow Depth = 4.72" for 25 -year event 1.83 cfs @ 12.07 hrs, Volume= 0.138 af 1.04 cfs @ 12.17 hrs, Volume= 0.138 af, Atten= 43%, Lag= 6.3 min 0.03 cfs @ 7.50 hrs, Volume= 0.094 af 1.01 cfs @ 12.17 hrs, Volume= 0.043 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 27.37' @ 12.17 hrs Surf.Area= 1,210 sf Storage= 2,391 cf Flood Elev= 27.50' Surf.Area= 1,210 sf Storage= 2,445 cf Plug -Flow detention time= 522.5 min calculated for 0.138 af (100% of inflow) Center -of -Mass det. time= 522.5 min ( 1,288.3 - 765.8 ) Volume Invert Avail.Storage Storage Description #1 24.00' 963 cf #2 24.50' 1,481 cf 20.50'W x 59.00'L x 3.50'H Crushed Stone 4,233 cf Overall - 1,481 cf Embedded = 2,752 cf x 35.0% Voids ADS_StormTech SC -740 x 32 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 4 rows Device Routing 2,445 cf Total Available Storage Invert Outlet Devices #1 Primary #2 Device 1 #3 Discarded 24.50' 12.0" Round Culvert L= 85.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 24.50' / 23.65' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 0.79 sf 27.20' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 24.00' 1.020 in/hr Exfiltration over Surface area Proposed Watershed Type III 24 -hr 25 -year Rainfall=5.30" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 35 Discarded OutFlow Max=0.03 cfs @ 7.50 hrs HW=24.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=1.00 cfs @ 12.17 hrs HW=27.37' (Free Discharge) L1=Culvert (Passes 1.00 cfs of 5.35 cfs potential flow) L2=Broad-Crested Rectangular Weir (Weir Controls 1.00 cfs @ 1.16 fps) Summary for Pond 5P: RAIN GARGEN Inflow Area = 1.470 ac, 42.18% Impervious, Inflow Depth = 3.60" for 25 -year event Inflow = 6.20 cfs @ 12.07 hrs, Volume= 0.440 af Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 100%, Lag= 0.0 min Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 28.67' @ 24.29 hrs Surf.Area= 12,566 sf Storage= 19,184 cf Plug -Flow detention time= (not calculated: initial storage excedes outflow) Center -of -Mass det. time= (not calculated: no outflow) Volume Invert Avail.Storage Storage Description #1 27.00' 23,450 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 27.00 10,500 0 0 28.00 11,700 11,100 11,100 29.00 13,000 12,350 23,450 Device Routing Invert Outlet Devices #1 Primary 28.75' 12.0" Round Culvert L= 66.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 28.75' / 27.38' S= 0.0208 '/' Cc= 0.900 n= 0.013, Flow Area= 0.79 sf Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=27.00' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) Proposed Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 36 Time span=0.00-48.00 hrs, dt=0.01 hrs, 4801 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1AS: Subcatchment 1 BS: COURTYARD Subcatchment 1S: Subcatchment2AS: ROOF Subcatchment2BS: GARAGE Subcatchment2CS: Subcatchment2DS: COURTYARD Subcatchment 3S: ROOF Subcatchment4S: Subcatchment 5S: Subcatchment 6S: Subcatchment 7S: Reach 1R: DESIGN POINT 1 Reach 2R: DESIGN POINT 2 Runoff Area=1.330 ac 85.71% Impervious Runoff Depth=5.91" Tc=5.0 min CN=95 Runoff=8.63 cfs 0.655 af Runoff Area=0.230 ac 91.30% Impervious Runoff Depth=6.03" Tc=5.0 min CN=96 Runoff=1.50 cfs 0.115 of Runoff Area=0.140 ac 28.57% Impervious Runoff Depth=4.34" Tc=5.0 min CN=81 Runoff=0.73 cfs 0.051 af Runoff Area=2.060 ac 100.00% Impervious Runoff Depth=6.26" Tc=5.0 min CN=98 Runoff=13.60 cfs 1.075 af Runoff Area=0.740 ac 100.00% Impervious Runoff Depth=6.26" Tc=5.0 min CN=98 Runoff=4.89 cfs 0.386 af Runoff Area=0.640 ac 57.81% Impervious Runoff Depth=5.11" Tc=5.0 min CN=88 Runoff=3.82 cfs 0.272 af Runoff Area=0.280 ac 89.29% Impervious Runoff Depth=5.91" Tc=5.0 min CN=95 Runoff=1.82 cfs 0.138 af Runoff Area=0.850 ac 82.35% Impervious Runoff Depth=5.79" Tc=5.0 min CN=94 Runoff=5.47 cfs 0.410 af Runoff Area=0.350 ac 85.71% Impervious Runoff Depth=5.91" Tc=5.0 min CN=95 Runoff=2.27 cfs 0.172 af Runoff Area=0.550 ac 0.00% Impervious Runoff Depth=3.61" Tc=5.0 min CN=74 Runoff=2.41 cfs 0.165 af Runoff Area=0.550 ac 74.55% Impervious Runoff Depth=5.56" Tc=5.0 min CN=92 Runoff=3.47 cfs 0.255 af Runoff Area=0.280 ac 0.00% Impervious Runoff Depth=3.61" Tc=5.0 min CN=74 Runoff=1.23 cfs 0.084 af Inflow=0.73 cfs 0.051 af Outflow=0.73 cfs 0.051 af Inflow=21.78 cfs 1.264 af Outflow=21.78 cfs 1.264 af Pond 1P: INFILTRATION BASIN 1 Peak Elev=27.46' Storage=8,348 cf Inflow=10.13 cfs 0.770 af Discarded=0.23 cfs 0.459 af Primary=9.57 cfs 0.311 af Outflow=9.80 cfs 0.770 af Pond 2P: INFILTRATION BASIN 2 Peak EIev=29.04' Storage=20,810 cf Inflow=18.49 cfs 1.565 af Discarded=0.61 cfs 1.198 af Primary=7.96 cfs 0.367 af Outflow=8.57 cfs 1.565 af Proposed Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 37 Pond 3P: INFILTRATION BASIN 3 Peak Elev=29.50' Storage=4,240 cf Inflow=5.47 cfs 0.410 af Discarded=0.12 cfs 0.238 af Primary=5.28 cfs 0.173 af Outflow=5.40 cfs 0.410 af Pond 4P: INFILTRATION BASIN 4 Peak EIev=27.49' Storage=2,439 cf Inflow=2.27 cfs 0.172 af Discarded=0.03 cfs 0.098 af Primary=2.19 cfs 0.074 af Outflow=2.22 cfs 0.172 af Pond 5P: RAIN GARGEN Peak Elev=28.91' Storage=22,321 cf Inflow=8.05 cfs 0.576 af 12.0" Round Culvert n=0.013 L=66.0' S=0.0208 '/' Outflow=0.11 cfs 0.104 af Total Runoff Area = 8.000 ac Runoff Volume = 3.779 af Average Runoff Depth = 5.67" 22.25% Pervious = 1.780 ac 77.75% Impervious = 6.220 ac Proposed Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 38 Summary for Subcatchment lAS: Runoff = 8.63 cfs @ 12.07 hrs, Volume= 0.655 af, Depth= 5.91" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description 1.140 98 Pavement 0.190 74 >75% Grass cover, Good, HSG C 1.330 95 Weighted Average 0.190 14.29% Pervious Area 1.140 85.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 1 BS: COURTYARD Runoff = 1.50 cfs © 12.07 hrs, Volume= 0.115 af, Depth= 6.03" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description 0.210 98 Pavement 0.020 74 >75% Grass cover, Good, HSG C 0.230 96 Weighted Average 0.020 8.70% Pervious Area 0.210 91.30% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 1S: Runoff = 0.73 cfs @ 12.07 hrs, Volume= 0.051 af, Depth= 4.34" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description 0.040 98 Pavement 0.100 74 >75% Grass cover, Good, HSG C 0.140 81 Weighted Average 0.100 71.43% Pervious Area 0.040 28.57% Impervious Area Proposed Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 39 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2AS: ROOF Runoff = 13.60 cfs @ 12.07 hrs, Volume= 1.075 af, Depth= 6.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description * 2.060 98 Roof 2.060 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2BS: GARAGE Runoff = 4.89 cfs © 12.07 hrs, Volume= 0.386 af, Depth= 6.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description 0.740 98 Roof 0.740 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2CS: Runoff = 3.82 cfs @ 12.07 hrs, Volume= 0.272 af, Depth= 5.11" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description 0.370 98 Pavement 0.270 74 >75% Grass cover, Good, HSG C 0.640 88 Weighted Average 0.270 42.19% Pervious Area 0.370 57.81% Impervious Area Proposed Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 40 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2DS: COURTYARD Runoff = 1.82 cfs @ 12.07 hrs, Volume= 0.138 af, Depth= 5.91" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description 0.250 98 Pavement 0.030 74 >75% Grass cover, Good, HSG C 0.280 95 Weighted Average 0.030 10.71% Pervious Area 0.250 89.29% Impervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 3S: ROOF Runoff = 5.47 cfs @ 12.07 hrs, Volume= 0.410 af, Depth= 5.79" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description 0.700 98 Pavement 0.150 74 >75% Grass cover, Good, HSG C 0.850 94 Weighted Average 0.150 17.65% Pervious Area 0.700 82.35% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 4S: Runoff = 2.27 cfs @ 12.07 hrs, Volume= 0.172 af, Depth= 5.91" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Proposed Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 41 Area (ac) CN Description 0.300 98 Pavement 0.050 74 >75% Grass cover, Good, HSG C 0.350 95 Weighted Average 0.050 14.29% Pervious Area 0.300 85.71% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 5S: Runoff = 2.41 cfs @ 12.07 hrs, Volume= 0.165 af, Depth= 3.61" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description 0.550 74 >75% Grass cover, Good, HSG C 0.550 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 6S: Runoff = 3.47 cfs @ 12.07 hrs, Volume= 0.255 af, Depth= 5.56" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description 0.410 98 Pavement 0.140 74 >75% Grass cover, Good, HSG C 0.550 92 Weighted Average 0.140 25.45% Pervious Area 0.410 74.55% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Proposed Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 42 Summary for Subcatchment 7S: Runoff = 1.23 cfs @ 12.07 hrs, Volume= 0.084 af, Depth= 3.61" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Type II I 24 -hr 100 -year Rainfall=6.50" Area (ac) CN Description 0.280 74 >75% Grass cover, Good, HSG C 0.280 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Reach 1R: DESIGN POINT 1 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.140 ac, 28.57% Impervious, Inflow Depth = 4.34" for 100 -year event Inflow = 0.73 cfs @ 12.07 hrs, Volume= 0.051 af Outflow = 0.73 cfs @ 12.07 hrs, Volume= 0.051 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Summary for Reach 2R: DESIGN POINT 2 [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 7.860 ac, 78.63% Impervious, Inflow Depth = 1.93" for 100 -year event Inflow = 21.78 cfs @ 12.13 hrs, Volume= 1.264 of Outflow = 21.78 cfs @ 12.13 hrs, Volume= 1.264 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Summary for Pond 1P: INFILTRATION BASIN 1 Inflow Area = 1.560 ac, 86.54% Impervious, Inflow Depth = 5.93" for 100 -year event Inflow = 10.13 cfs @ 12.07 hrs, Volume= 0.770 af Outflow = 9.80 cfs @ 12.09 hrs, Volume= 0.770 af, Atten= 3%, Lag= 1.2 min Discarded = 0.23 cfs @ 8.29 hrs, Volume= 0.459 af Primary = 9.57 cfs @ 12.09 hrs, Volume= 0.311 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 27.46' @ 12.09 hrs Surf.Area= 4,120 sf Storage= 8,348 cf Flood Elev= 27.50' Surf.Area= 4,120 sf Storage= 8,406 cf Plug -Flow detention time= 180.5 min calculated for 0.770 af (100% of inflow) Center -of -Mass det. time= 180.5 min ( 940.5 - 760.0 ) Proposed Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description Type III 24 -hr 100 -year Rainfall=6.50" Printed 11/7/2013 Page 43 #1 24.00' 3,238 cf #2 24.50' 5,168 cf 40.00W x 103.00'L x 3.50'H Crushed Stone 14,420 cf Overall - 5,168 cf Embedded = 9,252 cf x 35.0% Voids ADS_StormTech SC -740 x 112 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 8 rows Device Routing 8,406 cf Total Available Storage Invert Outlet Devices #1 Primary #2 Device 1 #3 Discarded 24.50' 18.0" Round Culvert L= 23.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 24.50' / 24.27' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 1.77 sf 26.75' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 24.00' 2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.23 cfs @ 8.29 hrs HW=24.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.23 cfs) Primary OutFlow Max=9.57 cfs @ 12.09 hrs HW=27.46' (Free Discharge) L1=Culvert (Passes 9.57 cfs of 12.65 cfs potential flow) L2=Broad-Crested Rectangular Weir (Weir Controls 9.57 cfs @ 2.70 fps) Summary for Pond 2P: INFILTRATION BASIN 2 [81] Warning: Exceeded Pond 5P by 0.94' @ 12.19 hrs Inflow Area = Inflow = Outflow = Discarded = Primary = 4.270 ac, 80.09% Impervious, Inflow Depth > 4.40" for 100 -year event 18.49 cfs @ 12.07 hrs, Volume= 1.565 af 8.57 cfs @ 12.21 hrs, Volume= 1.565 af, Atten= 54%, Lag= 8.6 min 0.61 cfs @ 8.87 hrs, Volume= 1.198 af 7.96 cfs @ 12.21 hrs, Volume= 0.367 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 29.04' @ 12.21 hrs Surf.Area= 10,870 sf Storage= 20,810 cf Flood Elev= 29.50' Surf.Area= 10,870 sf Storage= 22,567 cf Plug -Flow detention time= 199.8 min calculated for 1.564 af (100% of inflow) Center -of -Mass det. time= 199.7 min ( 987.5 - 787.8 ) Volume Invert Avail.Storage Storage Description #1 26.00' 8,334 cf Crushed Stone (Prismatic)Listed below (Recalc) 38,045 cf Overall - 14,232 cf Embedded = 23,813 cf x 35.0% Voids #2 26.50' 8,702 cf ADS_StormTech SC -740 x 189 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 7 rows #3 26.50' 5,530 cf ADS_StormTech SC -740 x 120 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Proposed Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Type III 24 -hr 100 -year Rainfall=6.50" Printed 11/7/2013 Page 44 Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 6 rows Elevation (feet) 26.00 29.50 Surf.Area (sq-ft) 10,870 10,870 22,567 cf Total Available Storage Inc.Store (cubic -feet) 0 38,045 Device Routing Invert Outlet Devices Cum.Store (cubic -feet) 0 38,045 #1 #2 Device 1 #3 Primary 26.50' 24.0" Round Culvert L= 8.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 26.50' / 26.40' S= 0.0125 '/' Cc= 0.900 n= 0.012, Flow Area= 3.14 sf 28.40' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 Discarded 26.00' 2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.61 cfs @ 8.87 hrs HW=26.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.61 cfs) Primary OutFlow Max=7.95 cfs @ 12.21 hrs HW=29.04' (Free Discharge) L1=Culvert (Passes 7.95 cfs of 16.93 cfs potential flow) L2=Broad-Crested Rectangular Weir (Weir Controls 7.95 cfs @ 2.49 fps) Inflow Area = Inflow = Outflow = Discarded = Primary = Summary for Pond 3P: INFILTRATION BASIN 3 0.850 ac, 82.35% Impervious, Inflow Depth = 5.79" for 100 -year event 5.47 cfs @ 12.07 hrs, Volume= 0.410 af 5.40 cfs @ 12.08 hrs, Volume= 0.410 af, Atten= 1%, Lag= 0.7 min 0.12 cfs @ 8.30 hrs, Volume= 0.238 af 5.28 cfs @ 12.08 hrs, Volume= 0.173 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 29.50' @ 12.08 hrs Surf.Area= 2,091 sf Storage= 4,240 cf Flood Elev= 29.50' Surf.Area= 2,091 sf Storage= 4,241 cf Plug -Flow detention time= 186.9 min calculated for 0.410 af (100% of inflow) Center -of -Mass det. time= 186.9 min ( 952.4 - 765.5 ) Volume #1 #2 Invert Avail.Storaae Storage Description 26.00' 1,657 cf 20.50'W x 102.00'L x 3.50'H Crushed Stone 7,319 cf Overall - 2,584 cf Embedded = 4,735 cf x 35.0% Voids 26.50' 2,584 cf ADS_StormTech SC -740 x 56 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 4 rows 4,241 cf Total Available Storage Proposed Watershed Prepared by Tetra Tech HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Device Routing Invert Outlet Devices Type III 24 -hr 100 -year Rainfall=6.50" Printed 11/7/2013 Page 45 #1 Primary #2 Device 1 #3 Discarded 26.50' 15.0" Round Culvert L= 25.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 26.50' / 26.25' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 1.23 sf 29.00' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 26.00' 2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.12 cfs @ 8.30 hrs HW=26.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.12 cfs) Primary OutFlow Max=5.27 cfs @ 12.08 hrs HW=29.50' (Free Discharge) L1=Culvert (Passes 5.27 cfs of 9.10 cfs potential flow) L2=Broad-Crested Rectangular Weir (Weir Controls 5.27 cfs @ 2.12 fps) Inflow Area = Inflow = Outflow = Discarded = Primary = Summary for Pond 4P: INFILTRATION BASIN 4 0.350 ac, 85.71% Impervious, Inflow Depth = 5.91" for 100 -year event 2.27 cfs @ 12.07 hrs, Volume= 0.172 af 2.22 cfs @ 12.09 hrs, Volume= 0.172 af, Atten= 2%, Lag= 1.0 min 0.03 cfs @ 6.66 hrs, Volume= 0.098 af 2.19 cfs @ 12.09 hrs, Volume= 0.074 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 27.49' © 12.09 hrs Surf.Area= 1,210 sf Storage= 2,439 cf Flood Elev= 27.50' Surf.Area= 1,210 sf Storage= 2,445 cf Plug -Flow detention time= 438.9 min calculated for 0.172 af (100% of inflow) Center -of -Mass det. time= 438.9 min ( 1,199.7 - 760.8 ) Volume Invert Avail.Storage Storage Description #1 24.00' 963 cf #2 24.50' 1,481 cf 20.50'W x 59.00'L x 3.50'H Crushed Stone 4,233 cf Overall - 1,481 cf Embedded = 2,752 cf x 35.0% Voids ADS_StormTech SC -740 x 32 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 4 rows Device Routing 2,445 cf Total Available Storage Invert Outlet Devices #1 Primary #2 Device 1 #3 Discarded 24.50' 12.0" Round Culvert L= 85.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 24.50' / 23.65' S= 0.0100 '/' Cc= 0.900 n= 0.012, Flow Area= 0.79 sf 27.20' 5.0' long x 0.5' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 24.00' 1.020 in/hr Exfiltration over Surface area Proposed Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 11/7/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Page 46 Discarded OutFlow Max=0.03 cfs @ 6.66 hrs HW=24.04' (Free Discharge) L3=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=2.18 cfs @ 12.09 hrs HW=27.49' (Free Discharge) L1=Culvert (Passes 2.18 cfs of 5.46 cfs potential flow) L2=Broad-Crested Rectangular Weir (Weir Controls 2.18 cfs @ 1.53 fps) Summary for Pond 5P: RAIN GARGEN Inflow Area = 1.470 ac, 42.18% Impervious, Inflow Depth = 4.70" for 100 -year event Inflow = 8.05 cfs @ 12.07 hrs, Volume= 0.576 af Outflow = 0.11 cfs @ 20.20 hrs, Volume= 0.104 af, Atten= 99%, Lag= 487.5 min Primary = 0.11 cfs @ 20.20 hrs, Volume= 0.104 af Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.01 hrs Peak Elev= 28.91' @ 20.20 hrs Surf.Area= 12,887 sf Storage= 22,321 cf Plug -Flow detention time= 824.0 min calculated for 0.104 af (18% of inflow) Center -of -Mass det. time= 627.4 min ( 1,419.2 - 791.8 ) Volume Invert Avail.Storage Storage Description #1 27.00' 23,450 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 27.00 10,500 0 0 28.00 11,700 11,100 11,100 29.00 13,000 12,350 23,450 Device Routing Invert Outlet Devices #1 Primary 28.75' 12.0" Round Culvert L= 66.0' CPP, end -section conforming to fill, Ke= 0.500 Inlet / Outlet Invert= 28.75' / 27.38' S= 0.0208 '/' Cc= 0.900 n= 0.013, Flow Area= 0.79 sf Primary OutFlow Max=0.11 cfs @ 20.20 hrs HW=28.91' (Free Discharge) L1=Culvert (Inlet Controls 0.11 cfs @ 1.37 fps) Appendix C Groundwater Recharge Calculations 58 Irving Street & 202-204 Arsenal Street Watertown, MA Recharge Calculations Required Recharge Volume' Rv = F x impervious area Where: Rv = required recharge volume (acre-feet) F = target depth factor associated with each hydrologic soil group (inches) Impervious Area = pavement and rooftop area on site (acres) NRCS Hydrologic Soil Type Approx. Soil Texture Target Depth Factor (inches) Impervious Area (acre) Rv (acre-feet) Rv (cf) A sand 0.60 0.00 0.000 0 B loam 0.35 0.00 0.000 0 C silty loam 0.25 6.22 0.130 5,645 D clay 0.10 0.00 0.000 0 Total = 0.130 5,645 Provided Recharge Volume2 Infiltration Basin Static Storage Volume (acre-feet) Static Storage Volume (cf) 1 0.167 7,284 2 0.403 17,542 3 0.089 3,875 4 0.053 2,318 Total = 0.712 31,019 Notes: 1.) Refer to Massachusetts Stormwater Handbook Volume 3, Chapter 1, page 15 dated February 2008. 2.) Provided recharge volume is based on the Static Method, refer to Massachusetts Stormwater Handbook Volume 3, Chapter 1, page 18 dated February 2008. P:\26700\143-26700-13001\5upportDocs\Calcs\Drainage\Recharge & Drawdown Calcs.xlsx 11/7/2013 58 Irving Street & 202-204 Arsenal Street Watertown, MA Drawdown Calculations Drawdown Time' Tlmedrawdown = Rv (K)(Bottom Area) Where: Timedrawdown = time it takes the basin to drain completely (hours) Rv = storage volume (cubic feet) K = saturated hydraulic conductivity2 (feet/hour) Bottom Area = bottom area of recharge structure (square feet) Infiltration Basin Rv (cf) K (in/hr) Bottom Area (sf) Drawdown Time (hr) 1 7,284 2.41 4,120 8.8 2 17,542 2.41 10,870 8.0 3 3,875 2.41 2,091 9.2 4 2,318 1.02 1,210 22.5 Notes: 1.) Refer to Massachusetts Stormwater Handbook Volume 3, Chapter 1, page 25 dated February 2008. 2.) Refer to Massachusetts Stormwater Handbook Volume 3, Chapter 1, page 22 dated February 2008 (Rawls Rates Table). 3.) Refer to HydroCAD report. P:\26700\143-26700-13001\SupportDocs\Calcs\Drainage\Recharge & Drawdown Calcs.xlsx 11/7/2013 Proposed Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 10/31/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Stage -Area -Storage for Pond 1P: INFILTRATION BASIN 1 Elevation Surface Storage (feet) (sq-ft) (cubic -feet) 24.00 4,120 0 24.05 4,120 72 24.10 4,120 144 24.15 4,120 216 24.20 4,120 288 24.25 4,120 361 24.30 4,120 433 24.35 4,120 505 24.40 4,120 577 24.45 4,120 649 24.50 4,120 721 24.55 4,120 890 24.60 4,120 1,059 24.65 4,120 1,227 24.70 4,120 1,395 24.75 4,120 1,563 24.80 4,120 1,730 24.85 4,120 1,896 24.90 4,120 2,061 24.95 4,120 2,226 25.00 4,120 2,390 25.05 4,120 2,554 25.10 4,120 2,716 25.15 4,120 2,878 25.20 4,120 3,039 25.25 4,120 3,199 25.30 4,120 3,358 25.35 4,120 3,516 25.40 4,120 3,673 25.45 4,120 3,829 25.50 4,120 3,983 25.55 4,120 4,137 25.60 4,120 4,290 25.65 4,120 4,441 25.70 4,120 4,591 25.75 4,120 4,739 25.80 4,120 4,887 25.85 4,120 5,032 25.90 4,120 5,176 25.95 4,120 5,319 26.00 4,120 5,460 26.05 4,120 5,599 26.10 4,120 5,737 26.15 4,120 5,873 26.20 4,120 6,006 26.25 4,120 6,137 26.30 4,120 6,265 26.35 4,120 6,391 26.40 4,120 6,515 26.45 4,120 6,636 26.50 4,120 6,754 26.55 4,120 6,869 26.60 4,120 6,980 Elevation Surface Storage (feet) (sq-ft) (cubic -feet) 26.65 4,120 7,087 26.70 4,120 7,189 26.75 4,120 7,284 26.80 4,120 7,372 26.85 4,120 7,456 26.90 4,120 7,535 26.95 4,120 7,611 27.00 4,120 7,685 27.05 4,120 7,757 27.10 4,120 7,829 27.15 4,120 7,901 27.20 4,120 7,974 27.25 4,120 8,046 27.30 4,120 8,118 27.35 4,120 8,190 27.40 4,120 8,262 27.45 4,120 8,334 27.50 4,120 8,406 Proposed Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 10/31/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Stage -Area -Storage for Pond 2P: INFILTRATION BASIN 2 Elevation Surface Storage (feet) (sq-ft) (cubic -feet) 26.00 10,870 0 26.05 10,870 190 26.10 10,870 380 26.15 10,870 571 26.20 10,870 761 26.25 10,870 951 26.30 10,870 1,141 26.35 10,870 1,332 26.40 10,870 1,522 26.45 10,870 1,712 26.50 10,870 1,902 26.55 10,870 2,359 26.60 10,870 2,815 26.65 10,870 3,271 26.70 10,870 3,726 26.75 10,870 4,179 26.80 10,870 4,630 26.85 10,870 5,079 26.90 10,870 5,527 26.95 10,870 5,973 27.00 10,870 6,416 27.05 10,870 6,858 27.10 10,870 7,297 27.15 10,870 7,734 27.20 10,870 8,169 27.25 10,870 8,601 27.30 10,870 9,030 27.35 10,870 9,457 27.40 10,870 9,881 27.45 10,870 10,302 27.50 10,870 10,720 27.55 10,870 11,135 27.60 10,870 11,547 27.65 10,870 11,955 27.70 10,870 12,360 27.75 10,870 12,760 27.80 10,870 13,157 27.85 10,870 13,550 27.90 10,870 13,939 27.95 10,870 14,323 28.00 10,870 14,703 28.05 10,870 15,079 28.10 10,870 15,449 28.15 10,870 15,814 28.20 10,870 16,173 28.25 10,870 16,525 28.30 10,870 16,870 28.35 10,870 17,209 28.40 10,870 17,542 28.45 10,870 17,867 28.50 10,870 18,184 28.55 10,870 18,492 28.60 10,870 18,790 Elevation Surface Storage (feet) (sq-ft) (cubic -feet) 28.65 10,870 19,075 28.70 10,870 19,347 28.75 10,870 19,601 28.80 10,870 19,837 28.85 10,870 20,057 28.90 10,870 20,268 28.95 10,870 20,470 29.00 10,870 20,664 29.05 10,870 20,855 29.10 10,870 21,045 29.15 10,870 21,235 29.20 10,870 21,425 29.25 10,870 21,616 29.30 10,870 21,806 29.35 10,870 21,996 29.40 10,870 22,186 29.45 10,870 22,376 29.50 10,870 22,567 Proposed Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 10/28/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Stage -Area -Storage for Pond 3P: INFILTRATION BASIN 3 Elevation Surface Storage (feet) (sq-ft) (cubic -feet) 26.00 2,091 0 26.05 2,091 37 26.10 2,091 73 26.15 2,091 110 26.20 2,091 146 26.25 2,091 183 26.30 2,091 220 26.35 2,091 256 26.40 2,091 293 26.45 2,091 329 26.50 2,091 366 26.55 2,091 451 26.60 2,091 536 26.65 2,091 621 26.70 2,091 705 26.75 2,091 789 26.80 2,091 873 26.85 2,091 957 26.90 2,091 1,040 26.95 2,091 1,123 27.00 2,091 1,206 27.05 2,091 1,288 27.10 2,091 1,370 27.15 2,091 1,451 27.20 2,091 1,532 27.25 2,091 1,613 27.30 2,091 1,693 27.35 2,091 1,772 27.40 2,091 1,851 27.45 2,091 1,930 27.50 2,091 2,008 27.55 2,091 2,085 27.60 2,091 2,162 27.65 2,091 2,238 27.70 2,091 2,314 27.75 2,091 2,389 27.80 2,091 2,463 27.85 2,091 2,536 27.90 2,091 2,609 27.95 2,091 2,681 28.00 2,091 2,752 28.05 2,091 2,822 28.10 2,091 2,891 28.15 2,091 2,960 28.20 2,091 3,027 28.25 2,091 3,093 28.30 2,091 3,157 28.35 2,091 3,221 28.40 2,091 3,283 28.45 2,091 3,345 28.50 2,091 3,404 28.55 2,091 3,462 28.60 2,091 3,518 Elevation Surface Storage (feet) (sq-ft) (cubic -feet) 28.65 2,091 3,572 28.70 2,091 3,624 28.75 2,091 3,672 28.80 2,091 3,717 28.85 2,091 3,759 28.90 2,091 3,799 28.95 2,091 3,838 29.00 2,091 3,875 29.05 2,091 3,912 29.10 2,091 3,948 29.15 2,091 3,985 29.20 2,091 4,021 29.25 2,091 4,058 29.30 2,091 4,095 29.35 2,091 4,131 29.40 2,091 4,168 29.45 2,091 4,204 29.50 2,091 4,241 Proposed Watershed Type III 24 -hr 100 -year Rainfall=6.50" Prepared by Tetra Tech Printed 10/28/2013 HydroCAD® 10.00 s/n 05923 © 2012 HydroCAD Software Solutions LLC Stage -Area -Storage for Pond 4P: INFILTRATION BASIN 4 Elevation Surface Storage (feet) (sq-ft) (cubic -feet) 24.00 24.05 24.10 24.15 24.20 24.25 24.30 24.35 24.40 24.45 24.50 24.55 24.60 24.65 24.70 24.75 24.80 24.85 24.90 24.95 25.00 25.05 25.10 25.15 25.20 25.25 25.30 25.35 25.40 25.45 25.50 25.55 25.60 25.65 25.70 25.75 25.80 25.85 25.90 25.95 26.00 26.05 26.10 26.15 26.20 26.25 26.30 26.35 26.40 26.45 26.50 26.55 26.60 1,210 0 1,210 21 1,210 42 1,210 63 1,210 85 1,210 106 1,210 127 1,210 148 1,210 169 1,210 190 1,210 212 1,210 261 1,210 309 1,210 358 1,210 407 1,210 455 1,210 504 1,210 552 1,210 600 1,210 648 1,210 695 1,210 743 1,210 790 1,210 836 1,210 883 1,210 929 1,210 975 1,210 1,021 1,210 1,067 1,210 1,112 1,210 1,157 1,210 1,201 1,210 1,246 1,210 1,289 1,210 1,333 1,210 1,376 1,210 1,419 1,210 1,461 1,210 1,503 1,210 1,544 1,210 1,585 1,210 1,626 1,210 1,665 1,210 1,705 1,210 1,743 1,210 1,781 1,210 1,819 1,210 1,855 1,210 1,891 1,210 1,927 1,210 1,961 1,210 1,994 1,210 2,027 Elevation Surface Storage (feet) (sq-ft) (cubic -feet) 26.65 1,210 2,058 26.70 1,210 2,088 26.75 1,210 2,115 26.80 1,210 2,141 26.85 1,210 2,166 26.90 1,210 2,189 26.95 1,210 2,211 27.00 1,210 2,233 27.05 1,210 2,254 27.10 1,210 2,275 27.15 1,210 2,296 27.20 1,210 2,318 27.25 1,210 2,339 27.30 1,210 2,360 27.35 1,210 2,381 27.40 1,210 2,402 27.45 1,210 2,423 27.50 1,210 2,445 Appendix D Water Quality Calculations 58 Irving Street & 202-204 Arsenal Street Watertown, MA TSS Removal Efficiency Calculations TSS Removal Calculation Worksheet BMP C D E F TSS Removal Rate Starting TSS Load* Amount Removed (C*D) Remaining Load (D -E) Street Sweeping - 5% 0.05 1.00 0.05 0.95 Deep Sump and Hooded Catch Basin 0.25 0.95 0.24 0.71 Proprietary Treatment Practice 0.75 0.71 0.53 0.18 Subsurface Infiltration Structure 0.80 0.18 0.14 0.04 Total TSS Removal = 96% * Equals remaining load from previous BMP (E) which enters the BMP ** 18% TSS remaining, therefore the minimum 44% TSS removal prior to treatment BMP has been achieved ** P:\26700\143-26700-13001\SupportDocs\Calcs\Drainage\TSS Removal Calcs.xls 11/7/2013 58 Irving Street & 202-204 Arsenal Streel Watertown, MA TSS Removal Efficiency Calculations TSS Removal Calculation Worksheet BMP C D E F TSS Removal Rate Starting TSS Load* Amount Removed (C*D) Remaining Load (D -E) Street Sweeping - 5% 0.05 1.00 0.05 0.95 Deep Sump and Hooded Catch Basin 0.25 0.95 0.24 0.71 Rain Garden 0.90 0.71 0.64 0.07 Infiltration Basin 0.80 0.07 0.06 0.01 Total TSS Removal = 99% *Equals remaining load from previous BMP (E) which enters the BMP ** 7% TSS remaining, therefore the minimum 44% TSS removal prior to treatment BMP has been achieved ** P:\26700\143-26700-13001 \SupportDocs\Calcs\Drainage\TSS Removal Calcs.xls 11/7/2013 58 Irving Street & 202-204 Arsenal Street Watertown, MA TSS Removal Efficiency Calculations TSS Removal Calculation Worksheet BMP C D E F TSS Removal Rate Starting TSS Load* Amount Removed (C*D) Remaining Load (D -E) Street Sweeping - 5% 0.05 1.00 0.05 0.95 Deep Sump and Hooded Catch Basin 0.25 0.95 0.24 0.71 Total TSS Removal = *Equals remaining load from previous BMP (E) which enters the BMP 29% P:\26700\143-26700-13001\SupportDocs\Calcs\Drainage\TSS Removal Calcs.xls 11/7/2013 58 Irving Street & 202-204 Arsenal Street Watertown, MA Overall TSS Removal Calculations TSS Average Impervious Pervious Total Removal Area TSS Watershed Area Area Area Rate x Removal ID (ac) (ac) (ac) (%) TSS Rate BMP Description Street Sweeping (5%) + Deep 1 AS + 1 BS 1.35 0.21 1.56 96% 1.50 Sump Catch Basin + Stormceptor (75%) + Infiltration Basin (80%) 2CS + 2DS 0.62 0.30 0.92 99% 0.91 Street Sweeping (5%) + Deep Sump Catch Basin + Rain Garden (90%) + Infiltration Basin (80%) 4S 0.30 0.05 0.35 96% 0.34 Street Sweeping (5%) + Deep Sump Catch Basin + Stormceptor (75%) + Infiltration Basin (80%) 1S 0.04 0.10 0.14 29% 0.04 Street Sweeping (5%) + Deep Sump Catch Basin 6S 0.41 0.14 0.55 29% 0.16 Street Sweeping (5%) + Deep Sump Catch Basin 2.72 0.80 3.52 2.94 84% 58 Irving Street & 202-204 Arsenal Street Watertown, MA Water Quality Volume Calculations Infiltration Basin Amp (acres) DWQ (inches) VWQ (cubic feet) Provided Volume (cubic feet) 1 1.35 1.00 4,901 7,284 2 3.42 1.00 12,415 17,542 3 0.70 1.00 2,541 3,875 4 0.30 1.00 1,089 2,318 VWQ = (DWQ / 12 inches/foot) * (Amp * 43,560 square feet/acre) Where: VWQ = Required Water Quality Volume (in cubic feet) DWQ = Water Quality Depth (in inches) A,Mp = Impervious Area (in acres) Notes: 1.) Refer to Massachusetts Stormwater Handbook Volume 1, Chapter 1, page 9 dated February 2008. P:\26700\143-26700-13001\SupportDocs\Calcs\Drainage\Water Quality Calcs.xlsx 11/7/2013 58 Irving Street & 202-204 Arsenal Street Watertown, MA MaDEP Standard Method to Convert Required Water Quality Volume to a Discharge Rate Water Quality Unit Areas (acres) % Impervious Impervious Area (mi2) WQV (inches) CN Tc qu (csm/in) Q (cfs) Stormceptor Model Design Capacity (cfs) Impervious (A) Pervious Total (min) (hrs) WQU-1 1.35 0.15 1.50 90.0% 0.0021 0.5 98 5.0 0.08 780 0.82 STC-2400 1.06 WQU-2 0.16 0.05 0.21 76.2% 0.0003 0.5 98 5.0 0.08 780 0.10 STC-4501 0.28 WQU-3 0.14 0.00 0.14 100.0% 0.0002 0.5 98 5.0 0.08 780 0.09 STC-450 0.28 Water Quality Flow (WQF) = Q = (qu) (A) (WQV) Where: qu = the unit peak discharge (in csm/in) A = impervious surface drainage area (in square miles) WQV = water quality volume (in inches) Notes: 1. Refer to MaDEP Standard Method to Convert Required Water Quality Volume to a Discharge Rate for Sizing Flow Based Manufactured Proprietary Stormwater Treatment Practices, dated September 10, 2013. P:\26700\143-26700-13001\SupportDocs\Calcs\Drainage\Stormceptor\Water Quality Flow Calcs.xlsx 11/7/2013 Storrnceptor Stormceptor Design Summary PCSWMM for Stormceptor Project Information Date Project Name Project Number Location 10/23/2013 58 Irving Street & 202-204 Arsenal Street 143-26700-13001 Watertown, MA Designer Information Company Contact Tetra Tech SJW Notes WQU-1 Drainage Area Total Area (ac) Imperviousness (%) 1.5 90 The Stormceptor System model STC 2400 achieves the water quality objective removing 81% TSS for a NJDEP (clay, silt, sand) particle size distribution. Stormceptor Sizing Summary Rainfall Name State ID Years of Records Latitude Longitude BOSTON WSFO AP MA 770 1948 to 2005 42°21'38"N 71°0'38"W Water Quality Objective TSS Removal (%) 80 Upstream Storage Storage (ac -ft) Discharge (cfs) 0 0 Stormceptor Model TSS Removal % STC 450i 68 STC 900 77 STC 1200 77 STC 1800 77 STC 2400 81 STC 3600 82 STC 4800 85 STC 6000 85 STC 7200 88 STC 11000 91 STC 13000 91 STC 16000 92 Stormceptor Design Summary - 1/2 Storrnceptor Particle Size Distribution Removing silt particles from runoff ensures that the majority of the pollutants, such as hydrocarbons and heavy metals that adhere to fine particles, are not discharged into our natural water courses. The table below lists the particle size distribution used to define the annual TSS removal. NJDEP (cla , silt, sand) Particle Size Pm Distribution % Specific Gravity Settling Velocity ft/s Particle Size pm Distribution % Specific Gravity Settling Velocity ft/s 1 4 29 75 175 375 750 5 15 25 15 30 5 5 2.65 2.65 2.65 2.65 2.65 2.65 2.65 0.0012 0.0012 0.0025 0.0133 0.0619 0.1953 0.4266 Stormceptor Design Notes • Stormceptor performance estimates are based on simulations using PCSWMM for Stormceptor. • Design estimates listed are only representative of specific project requirements based on total suspended solids (TSS) removal. • Only the STC 450i is adaptable to function with a catch basin inlet and/or inline pipes. • Only the Stormceptor models STC 450i to STC 7200 may accommodate multiple inlet pipes. • Inlet and outlet invert elevation differences are as follows: Inlet and Outlet Pipe Invert Elevations Differences Inlet Pipe Configuration STC 450i STC 900 to STC 7200 STC 11000 to STC 16000 Single inlet pipe Multiple inlet pipes 3 in. 3 in. 1 in. 3 in. 3 in. Only one inlet pipe. • Design estimates are based on stable site conditions only, after construction is completed. • Design estimates assume that the storm drain is not submerged during zero flows. For submerged applications, please contact your local Stormceptor representative. • Design estimates may be modified for specific spills controls. Please contact your local Stormceptor representative for further assistance. • For pricing inquiries or assistance, please contact Rinker Materials 1 (800) 909-7763 www.rinkerstormceptor.com Stormceptor Design Summary - 2/2 Storrnceptor Stormceptor Design Summary PCSWMM for Stormceptor Project Information Date Project Name Project Number Location 10/23/2013 58 Irving Street & 202-204 Arsenal Street 143-26700-13001 Watertown, MA Designer Information Company Contact Tetra Tech SJW Notes WQU-2 Drainage Area Total Area (ac) Imperviousness (%) 0.21 76.2 The Stormceptor System model STC 450i achieves the water quality objective removing 88% TSS for a NJDEP (clay, silt, sand) particle size distribution. Stormceptor Sizing Summary Rainfall Name State ID Years of Records Latitude Longitude BOSTON WSFO AP MA 770 1948 to 2005 42°21'38"N 71°0'38"W Water Quality Objective TSS Removal (%) 80 Upstream Storage Storage (ac -ft) Discharge (cfs) 0 0 Stormceptor Model TSS Removal OA STC 450i 88 STC 900 STC 1200 STC 1800 STC 2400 STC 3600 STC 4800 STC 6000 STC 7200 STC 11000 STC 13000 STC 16000 93 93 93 95 95 97 97 97 98 98 99 Stormceptor Design Summary - 1/2 Storrnceptor Particle Size Distribution Removing silt particles from runoff ensures that the majority of the pollutants, such as hydrocarbons and heavy metals that adhere to fine particles, are not discharged into our natural water courses. The table below lists the particle size distribution used to define the annual TSS removal. NJDEP (cla , silt, sand) Particle Size Pm Distribution % Specific Gravity Settling Velocity ft/s Particle Size pm Distribution % Specific Gravity Settling Velocity ft/s 1 4 29 75 175 375 750 5 15 25 15 30 5 5 2.65 2.65 2.65 2.65 2.65 2.65 2.65 0.0012 0.0012 0.0025 0.0133 0.0619 0.1953 0.4266 Stormceptor Design Notes • Stormceptor performance estimates are based on simulations using PCSWMM for Stormceptor. • Design estimates listed are only representative of specific project requirements based on total suspended solids (TSS) removal. • Only the STC 450i is adaptable to function with a catch basin inlet and/or inline pipes. • Only the Stormceptor models STC 450i to STC 7200 may accommodate multiple inlet pipes. • Inlet and outlet invert elevation differences are as follows: Inlet and Outlet Pipe Invert Elevations Differences Inlet Pipe Configuration STC 450i STC 900 to STC 7200 STC 11000 to STC 16000 Single inlet pipe Multiple inlet pipes 3 in. 3 in. 1 in. 3 in. 3 in. Only one inlet pipe. • Design estimates are based on stable site conditions only, after construction is completed. • Design estimates assume that the storm drain is not submerged during zero flows. For submerged applications, please contact your local Stormceptor representative. • Design estimates may be modified for specific spills controls. Please contact your local Stormceptor representative for further assistance. • For pricing inquiries or assistance, please contact Rinker Materials 1 (800) 909-7763 www.rinkerstormceptor.com Stormceptor Design Summary - 2/2 Storrnceptor Stormceptor Design Summary PCSWMM for Stormceptor Project Information Date Project Name Project Number Location 10/23/2013 58 Irving Street & 202-204 Arsenal Street 143-26700-13001 Watertown, MA Designer Information Company Contact Tetra Tech SJW Notes WQU-3 Drainage Area Total Area (ac) Imperviousness (%) 0.14 100 The Stormceptor System model STC 450i achieves the water quality objective removing 89% TSS for a NJDEP (clay, silt, sand) particle size distribution. Stormceptor Sizing Summary Rainfall Name State ID Years of Records Latitude Longitude BOSTON WSFO AP MA 770 1948 to 2005 42°21'38"N 71°0'38"W Water Quality Objective TSS Removal (%) 80 Upstream Storage Storage (ac -ft) Discharge (cfs) 0 0 Stormceptor Model TSS Removal OA STC 450i 89 STC 900 STC 1200 STC 1800 STC 2400 STC 3600 STC 4800 STC 6000 STC 7200 STC 11000 STC 13000 STC 16000 94 94 94 96 96 97 97 98 98 98 99 Stormceptor Design Summary - 1/2 Storrnceptor Particle Size Distribution Removing silt particles from runoff ensures that the majority of the pollutants, such as hydrocarbons and heavy metals that adhere to fine particles, are not discharged into our natural water courses. The table below lists the particle size distribution used to define the annual TSS removal. NJDEP (cla , silt, sand) Particle Size Pm Distribution % Specific Gravity Settling Velocity ft/s Particle Size pm Distribution % Specific Gravity Settling Velocity ft/s 1 4 29 75 175 375 750 5 15 25 15 30 5 5 2.65 2.65 2.65 2.65 2.65 2.65 2.65 0.0012 0.0012 0.0025 0.0133 0.0619 0.1953 0.4266 Stormceptor Design Notes • Stormceptor performance estimates are based on simulations using PCSWMM for Stormceptor. • Design estimates listed are only representative of specific project requirements based on total suspended solids (TSS) removal. • Only the STC 450i is adaptable to function with a catch basin inlet and/or inline pipes. • Only the Stormceptor models STC 450i to STC 7200 may accommodate multiple inlet pipes. • Inlet and outlet invert elevation differences are as follows: Inlet and Outlet Pipe Invert Elevations Differences Inlet Pipe Configuration STC 450i STC 900 to STC 7200 STC 11000 to STC 16000 Single inlet pipe Multiple inlet pipes 3 in. 3 in. 1 in. 3 in. 3 in. Only one inlet pipe. • Design estimates are based on stable site conditions only, after construction is completed. • Design estimates assume that the storm drain is not submerged during zero flows. For submerged applications, please contact your local Stormceptor representative. • Design estimates may be modified for specific spills controls. Please contact your local Stormceptor representative for further assistance. • For pricing inquiries or assistance, please contact Rinker Materials 1 (800) 909-7763 www.rinkerstormceptor.com Stormceptor Design Summary - 2/2 Performance Evaluation L6lYetiry \1as:s;k-huscrrs Arniter. t Current User: MASTEP GUEST http://www.mastep.net/database/d eval_details.cfin?studylD=1712&rec... search UMass Stormwater Technologies Clearinghouse Project Information Stcrmwater Library The Database External Links Contact Test Report Details Log On (Registration I Forgot Password I Home Page Back to Summary Page I Back to Profile Stormceptor :: A product from IMBRIUM SYSTEMS CORPORATION :: General Information: This laboratory study found the Stormceptor STC 900 achieved 75% removal of "Bulk TSS", which MASTEP considers equivalent to Suspended Sediment Concentration (SSC). Influent sediment concentrations were slightly higher than the target range for laboratory studies, but removal efficiency was fairly consistent at all levels tested. Several field studies were described in this report. None are TARP compliant (too few tests), but results remain relatively consistent with lab studies, lending some degree of support to lab results/vendor claims. Tests were performed for three influent TSS target concentrations of 100, 200 and 300 mg/L; at various increments of the operating rate (i.e., 25%, 50%, 75%, 100%, and 125%). NJDEP weighting factors were applied to the test results to generate weighted average removal efficiency. MASTEP Rating 2: This study was conducted according to generally sound scientific principles. Some caveats exist regarding use of the study information. Report title Author Agency conducting study Funding source for study NJCAT Technology Verification - New Jersey Corporation for New Jersey Corporation for Manufacturer Stormceptor Advanced Technologies Advanced Technologies c/o Stormceptor Corporation L Report date Date system installed Study start date Study end date 09/09/2004 09/09/2004 - - Name, location of test site Watershed where test site % impervious surface in test Size of BMP drainage area exists watershed (acres) Performance claims statement used for this study: The Stormceptor® System Model STC 900 provides 75% "Bulk TSS" removal efficiency (as per NJDEP treatment efficiency calculation methodology) for laboratory simulated stormwater runoff with an average influent concentration of 295 mg/L and an average d50 particle size of 97 microns. TSS removal testing was conducted with sediment pre -loaded in the lower chamber to 50% sediment capacity for the STC 900. Note that MASTEP staff considers "Bulk TSS" to be equivalent to SSC. Rating /Verification given by agency conducting study: Based on the evaluation of the results from laboratory studies, sufficient data is available to support the Stormceptor® Claim: The Stormceptor® System Model STC 900 provides 75% "Bulk TSS" removal efficiency (as per NJDEP treatment efficiency calculation methodology) for laboratory simulated stormwater runoff with an average influent concentration of 295 mg/L and an average d50 particle size of 97 microns. TSS removal testing was conducted with sediment pre -loaded in the lower chamber to 50% sediment capacity for the STC 900. Average annual number of storms in Average annual rainfall at test site Average monthly rainfall during test test watershed (inches) period (inches) % of total annual rainfall monitored Number of storms that occurred during Number of storm events that were during study study period monitored during the study 1 of 2 3/26/2013 11:48 AM Performance Evaluation http://www.mastep.net/database/d eval_details.cfm?studylD=1712&rec... Dates, precipitation amounts of storm events occurring Dates of storm events that were monitored during study during study Qualifying event minimum storm depth Maximum event recurrence interval Was bypass monitored? (inches) (years) Type of samples Parameters measured Analytical methods Statistical methods Pollution removal collected used used efficiency calculation methods Return to the Home Page © 2004 University of Massachusetts Amherst. Site Policies. This site is maintained by MaSTEP. Comments to: webmaster. STORMWATE TTCIiFJbLOGIESC1EARINC,HOUSt 2404 ThF5 pioject nas bees fInancen A r4L5 Federal Rums ftaias ma Envir'nmentaf Protection Agency (CPA) to the Massachusetts Department 01 EIMronmental Protection (the Department) under an s. 1L4 competltrre gtanL The contents do mot nee sarliy oMiect the views and poilctes of EPA or or the Department, not does the merman of trade names ce commercial paeduras ro sstJtute endio,sement or reconr sendatfon for use. 2 of 2 3/26/2013 11:48 AM Appendix E StormCAD Report StormCAD Report Label Start Node Elevation Stop Node Elevation Length Diameter Slope (Calculated) Manning's n Invert (Start) Invert (Stop) Velocity Flow Capacity (Full Hydraulic Ground (Start) Ground (Stop) (Unified) (in) (ft/ft) (ft) (ft) (ft/s) (cfs) Flow) Grade Line (ft) (ft) (ft) (cfs) (In) (ft) Hydraulic Cover Cover Grade Line (Start) (Stop) (Out) (ft) (ft) (ft) E-1 EDMH-2 40.62 E -CB 27.51 318 10.0 0.041 0.012 34.20 21.00 8.80 2.34 4.84 34.88 22.40 5.59 5.68 E-2 E -CB 27.51 DMH-19 28.30 149 12.0 0.004 0.013 20.80 20.20 2.98 2.34 2.26 22.40 21.76 5.71 7.10 P-1 CB -1 32.00 DMH-1 32.80 91 12.0 0.005 0.012 28.98 28.52 3.46 1.32 2.75 29.47 29.01 2.02 3.28 P-2 DMH-1 32.80 DMH-2 31.90 136 12.0 0.005 0.012 28.52 27.84 3.43 1.30 2.73 29.01 28.58 3.28 3.06 P-3 CB -2 31.80 DMH-2 31.90 9 12.0 0.005 0.012 27.89 27.84 3.49 1.22 2.85 28.58 28.58 2.91 3.06 P-4 DMH-2 31.90 DMH-3 32.70 153 12.0 0.005 0.012 27.84 27.07 3.94 2.45 2.74 28.58 27.86 3.06 4.63 P-5 CB -3 33.00 DMH-3 32.70 151 12.0 0.005 0.012 27.83 27.07 3.42 1.27 2.73 28.31 27.86 4.17 4.63 P-6 DMH-3 32.70 DMH-4 32.00 53 15.0 0.005 0.012 27.07 26.80 4.42 3.58 4.98 27.86 27.74 4.38 3.95 P-7 CB -4 31.80 DMH-4 32.00 9 12.0 0.006 0.012 26.85 26.80 3.41 1.03 2.93 27.74 27.74 3.95 4.20 P-8 DMH-4 32.00 DMH-5 33.00 106 15.0 0.005 0.012 26.80 26.27 4.58 4.53 4.96 27.74 27.13 3.95 5.48 P-9 CB -5 32.90 DMH-5 33.00 9 12.0 0.006 0.012 26.32 26.27 2.72 0.48 2.87 27.12 27.12 5.58 5.73 P-10 DMH-5 33.00 DMH-6 33.70 29 18.0 0.005 0.012 26.27 26.12 4.87 4.91 8.25 27.12 26.95 5.23 6.08 P-11 DMH-6 33.70 DMH-7 35.10 83 18.0 0.005 0.012 26.12 25.70 4.81 4.89 8.11 26.97 26.60 6.08 7.90 P-12 CB -6 34.90 DMH-7 35.10 32 12.0 0.005 0.012 25.86 25.70 2.31 0.32 2.71 26.60 26.60 8.04 8.40 P-13 AD -1 32.80 CB -7 34.90 21 12.0 0.010 0.012 26.00 25.80 1.73 0.05 3.76 26.60 26.60 5.80 8.10 P-14 CB -7 34.90 DMH-7 35.10 16 12.0 0.006 0.012 25.80 25.70 2.41 0.28 3.02 26.60 26.60 8.10 8.40 P-15 DMH-7 35.10 DMH-8 33.80 115 18.0 0.005 0.012 25.70 25.12 4.89 5.39 8.07 26.60 26.26 7.90 7.18 P-16 CB -8 32.90 DMH-8 33.80 62 12.0 0.005 0.012 25.43 25.12 3.50 1.41 2.73 26.33 26.26 6.47 7.68 P-17 TD -1 33.30 DMH-8 33.80 18 12.0 0.005 0.012 25.21 25.12 1.28 1.00 2.73 26.27 26.26 7.09 7.68 P-18 DMH-8 33.80 WQU-1 33.00 71 18.0 0.005 0.012 25.12 24.76 5.20 7.47 8.10 26.26 25.82 7.18 6.74 P-19 WQU-1 33.00 IFB-1 33.00 35 18.0 0.005 0.012 24.68 24.50 5.23 7.41 8.15 25.80 25.55 6.82 7.00 P-20 CB -9 31.80 DMH-9 32.40 137 12.0 0.005 0.012 27.85 27.17 3.14 0.93 2.72 28.25 28.09 2.95 4.23 P-21 CB -10 33.00 DMH-9 32.40 149 12.0 0.005 0.012 27.91 27.17 3.56 1.52 2.72 28.45 28.09 4.09 4.23 P-22 CB -11 31.20 DMH-9 32.40 107 12.0 0.005 0.012 27.71 27.17 3.78 1.93 2.74 28.33 28.09 2.49 4.23 P-23 DMH-9 32.40 FES-1 27.00 37 15.0 0.005 0.012 27.17 27.00 4.38 4.28 4.75 28.09 27.84 3.98 -1.25 P-24 FES-2 28.75 DMH-10 31.80 65 12.0 0.021 0.012 28.75 27.38 2.80 0.11 5.58 28.89 27.48 -1.00 3.42 P-25 DMH-10 31.80 DMH-11 33.00 69 12.0 0.010 0.012 27.38 26.69 2.17 0.11 3.87 27.52 26.81 3.42 5.31 P-26 DMH-11 33.00 IFB-2 33.00 19 12.0 0.010 0.012 26.69 26.50 2.18 0.11 3.91 26.83 26.62 5.31 5.50 P-27 WQU-2 29.50 IFB-4 29.80 14 12.0 0.007 0.012 24.60 24.50 3.66 1.05 3.21 25.03 24.90 3.90 4.30 P-28 CB -14 32.90 WQU-3 34.50 41 12.0 0.010 0.012 25.30 24.90 3.16 0.40 3.83 25.56 25.12 6.60 8.60 P-29 CB -15 32.90 WQU-3 34.50 23 12.0 0.013 0.012 25.20 24.90 3.47 0.40 4.37 25.46 25.11 6.70 8.60 P-30 WQU-3 34.50 IFB-4 30.00 15 12.0 0.010 0.012 24.65 24.50 3.87 0.80 3.86 25.02 24.81 8.85 4.50 P-31 DMH-12 33.00 DMH-14 33.00 23 18.0 0.010 0.012 24.50 24.27 6.55 5.97 11.45 25.64 25.65 7.00 7.23 P-32 DMH-13 33.00 DMH-14 33.00 8 24.0 0.012 0.012 26.50 26.40 7.67 8.77 26.98 27.56 27.31 4.50 4.60 P-33 DMH-14 33.00 DMH-15 29.50 58 24.0 0.010 0.012 24.27 23.69 8.14 14.74 24.45 25.65 24.84 6.73 3.81 P-34 DMH-15 29.50 DMH-17 29.50 32 24.0 0.010 0.012 23.69 23.36 8.30 14.74 25.05 25.07 24.91 3.81 4.14 P-35 DMH-16 31.00 DMH-17 29.50 25 15.0 0.010 0.012 26.50 26.25 5.89 3.87 7.06 27.30 26.93 3.25 2.00 P-36 DMH-17 29.50 DMH-18 29.50 60 24.0 0.010 0.012 23.36 22.76 8.59 18.61 24.53 24.91 24.09 4.14 4.74 P-37 DMH-18 29.50 DMH-19 28.30 40 24.0 0.010 0.012 20.60 20.20 8.62 18.61 24.66 22.15 21.76 6.90 6.10 P-38 DMH-19 28.30 DMH-20 27.60 74 30.0 0.005 0.012 20.20 19.84 6.79 20.95 31.06 21.76 21.49 5.60 5.26 P-39 CB -12 27.50 DMH-20 27.60 8 12.0 0.006 0.012 23.50 23.45 2.86 0.51 3.00 23.80 23.73 3.00 3.15 P-40 DMH-20 27.60 DMH-22 28.50 106 30.0 0.004 0.012 19.84 19.42 6.28 21.46 27.98 21.49 21.21 5.26 6.58 P-41 DMH-21 31.50 DMH-22 28.50 85 12.0 0.010 0.012 24.50 23.65 4.14 1.01 3.86 24.92 24.00 6.00 3.85 P-42 CB -13 28.50 DMH-22 28.50 9 12.0 0.005 0.012 24.50 24.45 3.89 1.90 2.86 25.10 25.04 3.00 3.05 P-43 DMH-22 28.50 DMH-23 28.61 40 30.0 0.004 0.012 19.42 19.26 6.45 24.34 28.14 21.21 21.05 6.58 6.85 P-44 DMH-23 28.61 OF -1 27.00 65 30.0 0.004 0.012 19.26 19.00 6.46 24.34 28.16 21.05 20.68 6.85 5.50 P-45 EDMH-1 43.44 DMH-24 48.00 93 10.0 0.015 0.012 38.00 36.61 5.93 2.34 2.90 38.68 37.18 4.61 10.56 Watertown StormCAD.stsw 11/6/2013 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Bentley StormCAD V8i (SELECTseries 3) [08.11.03.83] Page 1 of 2 StormCAD Report Label Start Node Elevation Stop Node Elevation Length Diameter Slope (Calculated) Manning's n Invert (Start) Invert (Stop) Velocity Flow Ground (Start) Ground (Stop) (Unified) (in) (ft/ft) (ft) (ft) (ft/s) (cfs) (ft) (ft) (ft) P-46 P-47 P-48 DMH-24 DMH-25 AD -2 48.00 46.00 39.00 DMH-25 EDMH-2 E -CB 46.00 40.62 39.83 35 112 20 10.0 10.0 12.0 0.015 0.015 0.010 0.012 0.012 0.012 36.61 36.08 35.00 36.08 34.40 34.80 5.96 5.92 3.06 2.34 2.34 0.35 Capacity (Full Hydraulic Hydraulic Cover Cover Flow) Grade Line Grade Line (Start) (Stop) (cfs) (In) (Out) (ft) (ft) (ft) (ft) 2.92 37.29 36.65 10.56 9.09 2.90 36.76 34.97 9.09 5.39 3.86 35.25 35.00 3.00 4.03 Bentley StormCAD V8i (SELECTseries 3) Watertown StormCAD.stsw Bentley Systems, Inc. Haestad Methods Solution Center [08.11.03.83] 11/6/2013 27 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 2 of 2 58 Irving Street & 202-204 Arsenal Street Watertown, MA StormCAD Worksheet - Catch Basin Flows Inlet Paved Unpaved Composite C Total Area (acres) Q (cfs) Area (acres) C Factor Area (acres) C Factor AD -1 0.00 0.95 0.02 0.45 0.45 0.02 0.05 AD -2 0.00 0.95 0.13 0.45 0.45 0.13 0.36 CB -1 0.21 0.95 0.04 0.45 0.87 0.25 1.33 CB -2 0.20 0.95 0.03 0.45 0.88 0.23 1.24 CB -3 0.21 0.95 0.02 0.45 0.91 0.23 1.27 CB -4 0.17 0.95 0.02 0.45 0.90 0.19 1.04 CB -5 0.08 0.95 0.01 0.45 0.89 0.09 0.49 CB -6 0.05 0.95 0.01 0.45 0.87 0.06 0.32 CB -7 0.04 0.95 0.00 0.45 0.95 0.04 0.23 CB -8 0.24 0.95 0.01 0.45 0.93 0.25 1.42 CB -9 0.11 0.95 0.11 0.45 0.70 0.22 0.94 CB -10 0.25 0.95 0.03 0.45 0.90 0.28 1.53 CB -11 0.26 0.95 0.16 0.45 0.76 0.42 1.95 CB -12 0.08 0.95 0.02 0.45 0.85 0.10 0.52 CB -13 0.33 0.95 0.00 0.45 0.95 0.33 1.91 CB -14 0.07 0.95 0.00 0.45 0.95 0.07 0.41 CB -15 0.07 0.95 0.00 0.45 0.95 0.07 0.41 TD -1 0.15 0.95 0.05 0.45 0.83 0.20 1.01 WQU-2 0.16 0.95 0.05 0.45 0.83 0.21 1.06 Notes: 1.) Shaded colums indicate input values. 2.) Q (flow) = composite C x rainfall intensity (inches/hr) x Total Area (acres). 3.) Rainfall intensity i = 6.0 inches/hr for the 25 year storm event. P:\26700\143-26700-13001\SupportDocs\Calcs\Drainage\StormCAD\StormCAD Worksheets.xlsx 11/7/2013 Appendix F Operations and Maintenance Plan Operations and Maintenance Plan 58 Irving Street & 202.204 Arsenal Street Watertown, Massachusetts Submitted to: Town of Watertown December 10. 2013 Table of Contents 1.0 Introduction 1 1.1 Responsibility 1 2.0 Maintenance Program 2 2.1 Inspection and Maintenance Frequency and Corrective Measures 2 2.1.1 Area Drains 3 2.1.2 Catch Basins 3 2.1.3 Parking Surfaces and Site Access Drives 3 2.1.4 Vegetated Areas 3 2.1.5 Stormceptor® Water Quality Structures 3 2.1.6 StormTech® Subsurface Infiltration Basin 3 2.2 Winter Maintenance Program 4 2.3 Fertilizer Use 4 3.0 Emergency Spill Containment 4 Tetra Tech List of Figures Figure 1 Stormwater Management Plan List of Appendices Appendix A Sample Operation and Maintenance Log and Inspection Forms Appendix B Stormceptor Owner's Manual Appendix C StormTech IsolatorTM Row O&M Manual Tetra Tech 1.0 Introduction This long-term Stormwater Management System Operations and Maintenance (O&M) Plan, filed with the Town of Watertown, shall be implemented at the Hanover R.S. Limited Partnership and Cressent W/S Venture LLC project located at 58 Irving Street and 202-204 Arsenal Street to ensure that the stormwater management system function as designed. The Owner possesses the primary responsibility for overseeing and implementing the O&M Plan and assigning a property manager who will be responsible for the proper operation and maintenance of the stormwater structures. In case of transfer of property ownership, future property owners shall be notified of the presence of the stormwater management system and the requirements for proper implementation of the O&M Plan. Included in the manual is a Stormwater Management O&M Plan identifying the key components of the stormwater system and a log for tracking inspections and maintenance. The stormwater management system protects and enhances the stormwater runoff water quality through the removal of sediment and pollutants, and source control significantly reduces the amount of pollutants entering the system. Preventive maintenance of the system will include a comprehensive source reduction program of regular vacuuming and litter removal, prohibitions on the use of pesticides, and maintenance of trash areas. 1.1 Responsibility The purpose of the Stormwater Operations and Maintenance (O&M) plan is to ensure inspection of the system, removal of accumulated sediments, oils, and debris, and implementation of corrective action and record keeping activities. The below O&M activities may be performed by a Contract Operator for the scope of facilities. The Contract Operator will be a professional engineer or other technical professional with expertise and experience with storm water management facilities operation and maintenance. The ongoing responsibility is the Owner, its successors and assigns. Adequate maintenance is defined in this document as good working condition. Contact information is provided below: Responsibility for Operations and Maintenance Name: TBD Address: TBD City, State: TBD Contact: TBD Telephone: TBD 1.2 Documentation An Operation and Maintenance Record Log and Schedule will be kept by the Owner summarizing inspections, maintenance, repairs and any corrective actions taken. The log will include the date on which each inspection or maintenance task was performed, a description of the inspection findings or maintenance completed, and the name of the inspector or maintenance Tetra Tech 1 personnel performing the task. If a maintenance task requires the clean -out of any sediments or debris, the location where the sediment and debris was disposed after removal will be indicated. Maintenance logs will be kept on file at the Facilities office and copies of Inspection & Maintenance Log sheets indicating all work and inspections will be available to the Town of Watertown upon request. 1.3 Public Safety Features The following measures have been incorporated into the stormwater management system to ensure the safety of the public: • Drain manholes and catch basins have been provided with heavy duty covers and/or grates and designed to withstand H2O loading. • Treatment of stormwater runoff from paved surfaces has been designed to remove 80% TSS, or to the maximum extent practicable. • Reduction in peak rates of runoff from the site under post -development conditions. • Development and implementation of an Operations and Maintenance Plan to ensure the proper functioning of the stormwater management system. • Development and implementation of a Long Term Pollution Prevention Plan identifying potential pollution sources and suitable practices to control them from impacting the environment and/or the public's health and safety. 2.0 Maintenance Program The property manager and maintenance staff will conduct the Operation and Maintenance program set forth in this document. The Director of Facilities will ensure that inspections and record keeping are timely and accurate and that cleaning and maintenance are performed at least on a bi-annual basis. Inspection & Maintenance Log Forms shall include the date and the amount of the last significant storm event in excess of 1" of rain in a 24-hour period, physical conditions of the structures, depth of sediment in structures, evidence of overtopping or debris blockage and maintenance required of each structure. Estimated annual cost of the Maintenance Program is $2,000 to $4,000. 2.1 Inspection and Maintenance Frequency and Corrective Measures The following areas, facilities, and measures will be inspected by the Owner and maintained as specified below. Identified deficiencies will be corrected. Accumulated sediments and debris will be properly handled and disposed of off -site, in accordance with local, state, and federal guidelines and regulations. Refer to Figure 1, Stormwater Management Plan for the components of the stormwater management system. A sample operation and maintenance log and inspection forms are included in Appendix A. Tetra Tech 2 2.1.1 Area Drains Area Drains will be inspected quarterly to ensure that the area drains are working in their intended fashion and that they are free of debris. Sediments and hydrocarbons will be properly handled and disposed of off -site, in accordance with local, state, and federal guidelines and regulations. The method of sediment removal will be manual and disposal must be documented. Any structural damage to the area drains or to castings must be repaired upon discovery. 2.1.2 Catch Basins Catch basins will be inspected quarterly and cleaned when sediment reaches '/z full depth from the invert of the pipe to ensure that the catch basins are working in their intended fashion and that they are free of debris. If the basin outlet is designed with a hood/tee to trap floatable materials, check to ensure watertight seal is working. Sediments and hydrocarbons will be properly handled and disposed of off -site, in accordance with local, state, and federal guidelines and regulations. The method of sediment removal will be by vacuum and disposal must be documented. Any structural damage to the catch basins or to castings must be repaired upon discovery. 2.1.3 Parking Surfaces and Site Access Drives Accumulations of sand and debris will be cleared from parking lots and site access drives through street sweeping to control the amount of sediment that enters the drainage system. Street sweeping will be conducted quarterly, but primarily in late spring and the early fall seasons. Street sweeping will also occur after winter snowmelt when road sand and other sediments have accumulated. 2.1.4 Vegetated Areas Inspect slopes and embankments early in the growing season to identify active or potential erosion problems. Replant bare areas or areas with sparse growth. Where rill erosion is evident, armor the area with an appropriate lining or divert the erosive flows to on -site areas able to withstand the concentrated flows. 2.1.5 Stormceptor° Water Quality Structures There are three (3) Stormceptor water quality units on site. Stormceptor® has defined the appropriate inspection and maintenance procedures. Refer to Appendix B of the O&M Plan for the procedure. 2.1.6 StormTech® Subsurface Infiltration Basin The stormwater management system includes four (4) subsurface infiltration basin constructed of StormTech® Chambers and Isolator Rows. StormTech® has defined the appropriate inspection and maintenance procedures. Refer to Appendix C of the O&M Plan for the procedure. Tetra Tech 3 2.2 Winter Maintenance Program The landowner will contract with a professional snow removal/winter conditions management contractor to treat the paved parking and walking areas within the project site for safe access during winter conditions. Each storm brings a specific treatment regime based on the temperature regime and precipitation type/amount. The contractor is responsible to minimize de- icing applications while ensuring safe vehicle and pedestrian access to the office park. In addition to snow removal, potentially icy and unsafe paved surfaces are addressed as follows. The de-icing program will utilize a non -sodium pelletized de-icing material that may contain calcium chloride or magnesium chloride as the active ice melting ingredient. 2.3 Fertilizer Use Only slow -release organic low -phosphorous fertilizers will be used in any landscaped areas in order to limit the amount of nutrients that could enter the stormwater system. 3.0 Emergency Spill Containment A spill of greater than 10 gallons of oil or a spill of any quantity that has reached a surface water, into a sewer, storm drain, ditch, or culvert leading to a surface water, shall be immediately reported to one or more municipal, state, or federal authority. In the event of a hazardous waste spill on -site the following protocol should be followed. • If it is safe to do so, employees (or on -site property manager) detecting an oil spill should immediately stop the release and use available materials to prevent the spread of oil, particularly trying to discharge to catch basins. • If there is a potentially flammable, toxic, or explosive condition, evacuate the vicinity of the spill. • If is believed that a reportable or dangerous condition exists, immediately call your local Fire Department to notify them of the release. If is believed that a reportable condition exists, immediately call the Massachusetts Department of Environmental Protection (DEP) to notify them of the release. Call the DEP Emergency Response Section toll free statewide number, 1-888-304-1133. Be prepared to provide the following information to the DEP and the Fire Department: • Identity of the caller • Contact phone number • Location of the spill • Type of product spilled • Approximate quantity or product spilled Tetra Tech 4 • Extent of actual and/or potential water pollution • Date and time of spill • Cause of spill Contact a Licensed Site Professional (LSP) to assist in further handling of the material(s) and DEP. Tetra Tech 5 E E c E � F 0 N_ a LO 0 CV M 0 N ti ■ in ,MH-1 5 5 z 0 a o' U U) LU 0 n r ' V I 75 I E 5 o 0 0 0 o 0 � M cu W cQo __ 0� E LL ca L O O N W Cl)0 CD 0 LO w z 0 CL 2 O (� I > � cn m N � N co cn c E voi L o Q cu -6 E > o In N N (D N c (' N E m vj E C/) L o 0) 0 c L ca 00 c U LO J U 0 a / Project No.: 143-26700-13001 Designed By: SJw Drawn By: SJw Checked By: NHC 0 20' 40' 80' Fig. 1 SCALE: 1 - 40 _XREF Bar Measures 1 it Appendix A Sample Operation and Maintenance Log and Inspection Forms Sample Operation and Maintenance Log Site Maintenance Supervisor: Date: Routine D Response to Rainfall Event (_inches) Other BMP Frequency Structures Inspected Date Performed Comments Area Drains Quarterly Inspections Semi -Annual Cleaning Catch Basins Quarterly Inspections Semi -Annual Cleaning Rain Gardens Monthly Inspections Semi -Annual Cleaning Street Sweeping Quarterly Cleaning Vegetated Areas Maintenance as necessary Stormceptor Quarterly Units Inspections Maintenance when 15% storage capacity is reached (min once/year) Immediate Oil/Hazardous Material Removal StormTech Semi -Annual Isolator Rows Inspections Maintenance as necessary AREA DRAIN INSPECTION FORM 58 IRVING STREET AND 202-204 ARSENAL STREET WATERTOWN, MASSACHUSETTS OWNER: PROPERTY MANAGER: INSPECTED BY: DATE OF INSPECTION: AREA DRAIN INSPECTED: AD-1 AD-2 ACCEPTABLE NEEDS WORK NOTES FRAME AND GRATE OVERFLOW PIPE DEPTH OF SEDIMENT .a. DATE OF CLEANING: BY WHOM: DATE OF REPAIR: BY WHOM: NOTE ANY DISCREPANCIES AND SUGGESTED CORRECTIVE ACTIONS: CATCH BASIN INSPECTION FORM 58 IRVING STREET AND 202-204 ARSENAL STREET WATERTOWN, MASSACHUSETTS OWNER: PROPERTY MANAGER: INSPECTED BY: DATE OF INSPECTION: CATCH BASIN INSPECTED: ❑ ❑ ❑ ❑ ❑ ❑ ❑ ❑ ❑ ❑ ❑ ❑ ❑ ❑ ❑ CB-1 CB-2 CB-3 CB-4 CB-5 CB-6 CB-7 CB-8 CB-9 CB-10 CB-11 CB-12 CB-13 CB-14 CB-15 ACCEPTABLE NEEDS WORK NOTES FRAME AND GRATE BRICK/MORTAR 0 0 OUTLET 1 P,4" p PIPE OIL HOOD ., DEPTH OF SEDIMENT ii DATE OF CLEANING: BY WHOM: DATE OF REPAIR: BY WHOM: NOTE ANY DISCREPANCIES AND SUGGESTED CORRECTIVE ACTIONS: INFILTRATION BASIN INSPECTION FORM 58 IRVING STREET AND 202-204 ARSENAL STREET WATERTOWN, MASSACHUSETTS OWNER: PROPERTY MANAGER: INSPECTED BY: DATE OF INSPECTION: INFILTRATION BASIN INSPECTED: I FB-1 I FB-2 I FB-3 I FB-4 ACCEPTABLE NEEDS WORK NOTES INSPECTION PORT WITH SCREW -IN CAP STORMTECH CHAMBER 4" PVC RISER 00 00 00 oa o0 0o as o0 00 DATE OF CLEANING: BY WHOM: DATE OF REPAIR: BY WHOM: NOTE ANY DISCREPANCIES AND SUGGESTED CORRECTIVE ACTIONS: STORMCEPTOR INSPECTION FORM 58 IRVING STREET AND 202-204 ARSENAL STREET WATERTOWN, MASSACHUSETTS OWNER: PROPERTY MANAGER: INSPECTED BY: DATE OF INSPECTION: STORMCEPTOR INSPECTED: WQU-1 WQU-2 WQU-3 ACCEPTABLE NEEDS WORK NOTES FRAME AND COVER OIL PORT a INLET OUTLET WEIR A DEPTH OF SEDIMENT a A A A A DATE OF CLEANING: BY WHOM: DATE OF REPAIR: BY WHOM: NOTE ANY DISCREPANCIES AND SUGGESTED CORRECTIVE ACTIONS: Appendix B Stormceptor° Owner's Manual rk 1lAM[NmJAIl1 Owner's Manual Page I Stormceptor® Owner's Manual Contents 1. Stormceptor Overview 2. Stormceptor System Operation 3. Identification of Stormceptor 4. Stormceptor Maintenance Guidelines 4.1 Recommended Maintenance Procedure 4.2 Disposal of Trapped Material from Stormceptor 5. Recommended Safety Procedures 6. Stormceptor Monitoring Protocol 6.1 Pollutants to be Monitored 6.2 Monitoring Methodology Page List of Tables Table 1. Stormceptor Dimensions 4 Table 2. Stormceptor Capacities 5 Table 3. Sediment Depths Indicating Required Maintenance 5 Table 4. Monitoring Pollutants 9 List of Figures Figure 1. Single Inlet/Outlet "Disc" Insert In -Line Stormceptor 6 Figure 2. STC 450i Inlet Stormceptor 6 Rev. 3/2006 Rinker Materials www.rinkerstormceptor.com Owner's Manual Page 2 Thank You! We want to thank you for selecting the Stormceptor System to use in your efforts in protecting the environment. Stormceptor is one of the most effective and maintenance friendly storm water quality treatment devices available. If you have any questions regarding the operation and maintenance of the Stormceptor System, please call your local Rinker Materials representative, or the Stormceptor Information Line at (800) 909-7763. 1. Stormceptor Overview The Stormceptor System is a water quality device used to remove total suspended solids (TSS) and free oil (TPH) from storm water run-off. Stormceptor takes the place of a conventional manhole or inlet structure within a storm drain system. Rinker Materials manufactures the Stormceptor System with precast concrete components and a fiberglass disc insert. A fiberglass Stormceptor can also be provided for special applications. The Stormceptor System product line consists of four patented designs: • The In -Line (Conventional) Stormceptor, available in eight model sizes ranging from 900 to 7200 gallon storage capacity. • An In -Line (Series) Stormceptor is available in three model sizes ranging from 11,000 to 16,000 gallon storage capacity. • The Submerged Stormceptor, an in -line system designed for oil and sediment removal in partially submerged pipes, available in all models sizes ranging from 450i to 16,000 gallon storage capacity. • The Inlet Stormceptor is a 450 gallon unit designed for small drainage areas. Stormceptor removes free oil and suspended solids from storm water preventing hazardous spills and non -point source pollution from entering downstream lakes and rivers. Rinker Materials and its affiliates market and manufacture the Stormceptor System in the United States and Australia. Several thousand Stormceptor Systems have been installed in various locations throughout North America, Australia and the Caribbean since 1990. In the Stormceptor, a fiberglass insert separates the treatment chamber from the by-pass chamber. The different insert designs are illustrated in Figures 1 and 2. These designs are easily distinguishable from the surface once the cover has been removed. There are four versions of the in -line disc insert: single inlet/outlet, multiple inlet, in -line series insert and submerged designs. In the non -submerged "disc" design you will be able to see the inlet pipe, the drop pipe opening to the lower chamber, the weir, a 6" oil inspection/cleanout pipe, a large 24" riser pipe opening offset on the outlet side of the structure, and the outlet pipe from the unit. The weir will be around the 24" outlet pipe on the multiple inlet disc insert and on large diameter pipe applications. The STC (series) Stormceptors consist of two chambers comprised of similar fiberglass inserts. These units also contain a 6" oil/inspection cleanout pipe and 24" outlet riser pipes. The submerged disc insert has a higher weir and a second inlet drop pipe. In the inlet design you will be able to see an inlet drop pipe and an outlet riser pipe as well as a central oil inspection/cleanout port. Rinker Materials www.rinkerstormceptor.com Owner's Manual Page 3 2. Stormceptor System Operation The Stormceptor consists of a lower treatment chamber, which is always full of water, and a by-pass chamber. Storm water flows into the by-pass chamber via the storm sewer pipe or grated inlet (Inlet Stormceptor). Normal flows are diverted by a weir and drop pipe arrangement into a treatment chamber. Water flows up through the submerged outlet pipe based on the head at the inlet weir and is discharged back into the by-pass chamber downstream of the weir. The treated storm water continues down stream via the storm sewer system. Oil and other liquids with a specific gravity less than water rise in the treatment chamber and become trapped under the fiberglass insert. Sediment will settle to the bottom of the chamber by gravity. The circular design of the treatment chamber is critical to prevent turbulent eddy currents and to promote settling. During infrequent high flow conditions, storm water will by-pass the weir and be conveyed to the outlet sewer directly. The by-pass is an integral part of the Stormceptor since other oil/grit separators have been noted to scour during high flow conditions (Schueler and Shepp, 1993). For further details please refer to The Stormceptor System Technical Manual. The key benefits of Stormceptor include: • Capable of removing more than 80% of the total sediment load when properly applied as a source control for small drainage areas • Removes free oil from storm water during normal flow conditions • Will not scour or resuspend trapped pollutants • Ideal spill control device for commercial and industrial developments • Vertical orientation facilitates maintenance and inspections • Small foot print 3. Ident ication of Stormceptor All In -Line (including Submerged) Stormceptors are provided with their own frame and cover. The cover has the name STORMCEPTOR clearly embossed on it to allow easy identification of the unit. The name Stormceptor is not embossed on the inlet models due to the variability of inlet grates used/approved across North America. You will be able to identify the Inlet Stormceptor by looking into the grate since the insert will be visible. Once you have located a unit, there still may be a question as to the size of the unit. Comparing the measured depth from the water level (bottom of insert) to the bottom of the tank with Table 1 should help determine the size of the unit. Rinker Materials www.rinkerstormceptor.com Owner's Manual Page 4 Table 1. Stormceptor Dimensions* Model Pipe Invert to Top of Base Slab 450i 60" 900 55" 1200 71" 1800 105" 2400 94" 3600 134" 4800 128" 6000 150" 7200 134" 11000s 128"** 13000s 150"** 16000s 134"** * Depths are approximate * * Depths per structure Starting in 1996, a metal serial number tag has been affixed to the fiberglass insert. If the unit does not have a serial number, or if there is any uncertainty regarding the size of the Stormceptor using depth measurements, please contact the Rinker Materials Stormceptor information line at (800) 909-7763 for assistance. 4. Stormceptor Maintenance Guidelines The performance of all storm water quality measures that rely on sedimentation decreases as they fill with sediment (See Table 2 for Stormceptor capacities). An estimate of performance loss can be made from the relationship between performance and storage volume. Rinker Materials recommends maintenance be performed when the sediment volume in the unit reaches 15% of the total storage. This recommendation is based on several factors: Sediment removal is easier when removed on a regular basis (as sediment builds up it compacts and solidifies making maintenance more difficult). Development of a routine maintenance interval helps ensure a regular maintenance schedule is followed. Although the frequency of maintenance will depend on site conditions, it is estimated that annual maintenance will be required for most applications; annual maintenance is a routine occurrence which is easy to plan for and remember. A minimal performance degradation due to sediment build-up can occur. In the event of any hazardous material spill, Rinker Materials recommends maintenance be performed immediately. Maintenance should be performed by a licensed liquid waste hauler. You should also notify the appropriate regulatory agencies as required. Rinker Materials www.rinkerstormceptor.com Owner's Manual Page 5 Table 2. Stormceptor Capacities Model Sediment Capacity W (L) Oil Capacity US gal (L) Total Holding Capacity US gal (L) 450i 45 (1276) 86 (326) 470 (1779) 900 75 (2135) 251 (950) 952 (3604) 1200 113 (3202) 251 (950) 1234 (4671) 1800 193 (5470) 251 (950) 1833 (6939) 2400 155 (4387) 840 (3180) 2462 (9320) 3600 323 (9134) 840 (3180) 3715 (14063) 4800 465 (13158) 909 (3441) 5059 (19150) 6000 609 (17235) 909 (3441) 6136 (23227) 7200 726 (20551) 1059 (4009) 7420 (28088) 11000s 942 (26687) 2797 (10588)* 11194 (42374) 13000s 1230 (34841) 2797 (10588)* 13348 (50528) 16000s 1470 (41632) 3055 (11564)* 15918 (60256) * Total both structures combined 4.1 Recommended Maintenance Procedure For the "disc" design, oil is removed through the 6" inspection/cleanout pipe and sediment is removed through the 24" diameter outlet riser pipe. Alternatively, oil could be removed from the 24" opening if water is removed from the treatment chamber, lowering the oil level below the drop pipes. The depth of sediment can be measured from the surface of the Stormceptor with a dipstick tube equipped with a ball valve (Sludge Judge"). It is recommended that maintenance be performed once the sediment depth exceeds the guideline values provided in Table 3 for the reasons noted in Section 4.0 Stormceptor Maintenance Guidelines. Table 3. Sediment Depths Indicating Required Maintenance Model Sediment Depth* 450i 8" (200 mm) 900 8" (200 mm) 1200 10" (250 mm) 1800 15" (375 mm) 2400 12" (300 mm) 3600 17" (425 mm) 4800 15" (375 mm) 6000 18" (450 mm) 7200 15" 375 mm 11000s 17" (425 mm)** 13000s 20" (500 mm)** 16000s 17" (425 mm)** * Depths are approximate * * In each structure Rinker Materials www.rinkerstormceptor.com Owner's Manual Page 6 No entry into the unit is required for routine maintenance of the Inlet Stormceptor or the smaller disc insert models of the In -Line Stormceptor. Entry to the level of the disc insert may be required for servicing the larger disc insert models. Any potential obstructions at the inlet can be observed from the surface. The fiberglass insert has been designed as a platform for authorized maintenance personnel in the event that an obstruction needs to be removed. Typically, maintenance is performed by the Vacuum Service Industry, a well established sector of the service industry that cleans underground tanks, sewers, and catch -basins. Costs to clean a Stormceptor will vary based on the size of the unit and transportation distances. If you need assistance for cleaning a Stormceptor unit, contact your local Rinker Materials representative, or the Stormceptor Information Line at (800) 909-7763. Figures 1 and 2 will help illustrate the access point for routine maintenance of Stormceptor. Sediment and oil Oil removal can be removal can be performed by vacuum truck performed by vacuums through the oil/inspection port Disc Insert Concrete Stormceptor Figure 1 Single Inlet/Outlet "Disc" Insert In -Line Stormceptor Inlet Grate Oil Port Inlet Insert Removable Tee Maintenance Figure 2 STC 450i Inlet Stormceptor Rinker Materials www.rinkerstormceptor.com Owner's Manual Page 7 4.2 Disposal of Trapped Material from Stormceptor The requirements for the disposal of material from Stormceptor are similar to that of any other Best Management Practices (BMP). Local guidelines should be consulted prior to disposal of the separator contents. In most areas the sediment, once dewatered, can be disposed of in a sanitary landfill. It is not anticipated that the sediment would be classified as hazardous waste. In some areas, mixing the water with the sediment will create a slurry that can be discharged into a trunk sanitary sewer. In all disposal options, approval from the disposal facility operator/agency is required. Petroleum waste products collected in Stormceptor (oil/chemical/fuel spills) should be removed by a licensed waste management company. What if I see an oil rainbow or sheen at the Stormceptor outlet? With a steady influx of water with high concentrations of oil, a sheen may be noticeable at the Stormceptor outlet. This may occur because a rainbow or sheen can be seen at very small oil concen- trations (< 10 ppm). Stormceptor will remove over 95% of all free oil and the appearance of a sheen at the outlet with high influent oil concentrations does not mean that the unit is not working to this level of removal. In addition, if the influent oil is emulsified, the Stormceptor will not be able to remove it. The Stormceptor is designed for free oil removal and not emulsified or dissolved oil conditions. 5.0 Recommended Safety Procedures Rinker Materials strongly recommends that any person who enters a Stormceptor System follow all applicable OSHA regulations for entry in permit required confined spaces, as outlined in 29 CFR 1910.146. A permit required confined space consists of a space that: • Is large enough and so configured that an employee can bodily enter and perform assigned work. • Has limited or restricted means for entry and exit. • Is not designed for continuous employee occupancy. • Contains or has one of the following: - a potential to contain a hazardous atmosphere. - a material that has the potential for engulfing an entrant. - any other recognized serious safety hazard. Storm water and wastewater systems fall under OSHA guidelines for a permit required confined space. Failure to follow OSHA guidelines for entry and work in a permit required confined space can result in serious injury or death. Please exercise extreme caution and follow appropriate safety procedures when entering any confined space. Two square pick holes in the cover vent the Stormceptor, allow for removal of the cover, and provide sampling ports for air quality monitoring before the cover is removed. If you must enter the Stormceptor, please note that if the disc insert inside is wet, it can be slippery. Rinker Materials www.rinkerstormceptor.com Owner's Manual Page 8 Recognizing that every work site is different, the responsibility for safety falls on the contractor. The contractor must ensure that all employees and subcontractors follow established safety procedures and OSHA regulations for working in and around permit required confined spaces as well as for any other safety hazard that may be present on that particular site. 6.0 Stormceptor Monitoring Protocol If monitoring of your Stormceptor System is required, we recommend you follow the procedures outlined below by the Rinker Materials Stormceptor office. If you have any questions regarding monitoring please contact the Rinker Materials Stormceptor Product Manager at (800) 909-7763. 6.1 Pollutants to be Monitored Table 4 indicates the pollutants to be monitored during the storm events and the minimum acceptable detection limit for each pollutant to be analyzed. Approved federal or state laboratory analysis methodologies are to be used for the analysis. The optional metals indicated in Table 4 refer to the Resource Conservation Recovery Act and may be covered by a generic metals scan. Bacteria monitoring will not be required unless explicitly requested elsewhere. Two sediment samples are to be extracted from the monitored Stormceptor at the end of the study and analyzed for the particle size distribution and water content. A minimum of 8 U.S. sieve sizes should be used to determine the particle size distribution. Sieves that are used must include, but are not limited to 35, 60, 100, 140, 200, 270 and 400. Three clay particle sizes must be analyzed to denote particle sizes between 5 and 25 yam. The particle size distributions should be plotted on a standard grain size distribution graph. Rinker Materials www.rinkerstormceptor.com Owner's Manual Page 9 Table 4. Monitoring Pollutants Pollutant Minimum Detection Limit MDL Total Suspended Solids (TSS) 5 m /l Total Phosphorus (P) 0.02 mg/l Total K'eldahl Nitrogen TKN 0.1 m /l Copper (Cu) 0.001 mg/1 Cadmium (Cd) 0.005 m /l Lead (Pb) 0.05 mg/1 Zinc (Zn) 0.01 mg/1 Chromium (Cr) 0.01 mg/l Total Petroleum Hydrocarbons (TPH) 1 mg/l Conductivity 0.1 ytmho/cm Fecal Coliform* 1/100 ml Additional Metals (optional) Arsenic (As) 0.005 mg/l Barium (Ba) 0.01 mg/1 Mercury (Hg) 0.0005 mg/l Selenium (Se) 0.005 mg/l Silver (Ag) 0.01 mg/1 * Only if explicitly requested in Terms of Reference 6.2 Monitoring Methodology The following monitoring protocol should be followed to ensure reasonable monitoring results and interpretation: • Monitoring protocols should conform to EPA 40 CFR Part 136. • The EPA guideline of 72 hours dry period prior to a monitoring event should be used. This will ensure that there is sufficient pollutant build-up available for wash -off during the monitored event. • Flow proportional monitoring must be conducted for the parameters indicated in Table 1. Samples should be analyzed separately for the first flush versus the remainder of the storm event. Monitoring need not extend longer than an 8-hour period after the start of the storm event (composite). • Sediment sampling (measuring the sediment depth in the unit at the beginning and end of the monitoring period) must be conducted. The water content of the sediment layer must be analyzed to determine the dry volume of suspended solids. Sediment depth sampling will indicate the rate of pollution accumulation in the unit, provide confirmation that the unit is not scouring and confirm the flow proportional monitoring results. A mass balance using the sediment sampling should be calculated to validate the flow proportional sampling. Rinker Materials www.rinkerstormceptor.com Owner's Manual Page 10 • Grab sampling (just taking samples at the inlet and outlet) is an unacceptable methodology for testing the performance of the Stormceptor during wet weather conditions unless it is flow weighted (flow weighted composite sample from numerous grab samples) over the entire storm. • The oil containment area underneath the insert should be inspected via the vent pipe for dry weather spills capture once a month during the monitoring period since the flow rate of a dry weather spill may not trigger the automated samplers. • A tipping bucket rain gauge should be installed on -site to record the distribution of storm intensities and rainfall volume during the monitored events. • Results that are within the laboratory error (both inlet and outlet) or are representative of relatively clean water should be discarded. Typical concentrations of pollutants in storm water are: TSS 100 mg/L Total P 0.33 mg/L TKN 1.50 mg/L Total Cu 34 p g/L Total Pb 144 N g/L Total Zn 160 N g/L A threshold first flush/composite TSS value of 50 mg/L at the inlet to the Stormceptor should be used as the lower limit of an acceptable storm for reporting event efficiency. Monitoring results where the influent TSS concentration is less than 50 mg/L should only be used in mass load removal calculations over the entire monitoring period with other storms where the influent concentration is greater than 50 mg/L. The results should not be analyzed if the influent TSS concentrations during all monitored storms are less than 50 mg/L. Storms where the influent TSS concentration is less than 10 mg/L should be discarded from all analyses. • A threshold storm event volume equal to 1.5 times the storage volume of the Stormceptor being monitored should be used as the lower limit of an acceptable storm for monitoring. • Sampling at the outlet of the Stormceptor should be conducted within the 24" outlet riser pipe to accurately define event performance. • The personnel monitoring the Stormceptor should record incidental information in a log file. Information such as weather, site conditions, inspection and maintenance information, monitoring equipment failure, etc. provide valuable information that can explain anomalous results. • Laboratory results of monitored samples should be analyzed within 10 days of being submitted to the lab. • Weekly inspections of the sampling tubes, flow meter, rain gauge, and quality samplers should be conducted to ensure proper operation of the monitoring equipment. Debris and sediment that collects around the sampling intakes should be cleaned after each event. • During the installation of automated quality samplers, care should be exercised to ensure that representative samples will be extracted (placement of intakes, ensuring that tubing is not constricted or crimped). • Sampling should be conducted for a minimum of 6 storms. Ideally 15 storms should be sampled if the budget allows. Rinker Materials www.rinkerstormceptor.com Call the Stormceptor Information Line (800-909-7763) for more detailed informa- tion and test results. TECHNICAL INFORMATION: • Stormceptor CD ROM • Stormceptor Technical Manual • Stormceptor Installation Guide • Stormceptor Brochure TEST RESULTS: • STEP Report (Independent Verification) • University of Coventry Study • ETV Canada (Federal Verification) • National Water Research Institute Test • Westwood, MA Field Monitoring Study • Edmonton, Canada Field Monitoring Study • Seattle Field Monitoring • Como Park, MN Field Monitoring Study • Florida Atlantic University Submerged Stormceptor Testing • Oil Removal Field Validation • Sludge Analyses and Particle Size Analyses MATERIALS"' 6560 Langfield Rd., Bldg. 3 Houston, TX 77092 Phone: 832-590-5300 Fax: 832-590-5399 Toll Free: 800-909-7763 www.rinkerstormceptor.com 02006 Rinker Materials Corp. Rev.3/2006 Appendix C StormTech IsolatorTM Row O&M Manual 46 StormTe9che Detention • Retention • Recharge Subsurface Stormwater Managements°' d ■7 ti 11 � L IsolatorTM Row OW Manual StormTech° Chamber System for Stormwater Management 1.0 The Isolator TM Row 1.1 1NTRocIX.nCN An important component of any Stormwater Pollution Prevention Plan is inspection and maintenance. The StormTech Isolator Row is a patent pending technique to inexpensively enhance Total Suspended Solids (TSS) removal and provide easy access for inspection and maintenance. Looking down the Isolator Row from the manhole opening, woven geotextile is shown between the chamber and stone base. 1.2 1FUSIOLAYW RICIIW The Isolator Row is a row of StormTech chambers, either SC-740 or SC-310 models, that is surrounded with filter fabric and connected to a closely located manhole for easy access. The fabric -wrapped chambers provide for settling and filtration of sediment as storm water rises in the Isolator Row and ultimately passes through the filter fabric. The open bottom chambers and perforated side - walls allow storm water to flow both vertically and horizon- tally out of the chambers. Sediments are captured in the Isolator Row protecting the storage areas of the adja- cent stone and chambers from sediment accumulation. Two different fabrics are used for the Isolator Row. A woven geotextile fabric is placed between the stone and the Isolator Row chambers. The tough geotextile provides a media for storm water filtration and provides a durable surface for maintenance operations. It is also designed to prevent scour of the underlying stone and remain intact during high pressure jetting. A non -woven fabric is placed over the chambers to provide a filter media for flows passing through the perforations in the sidewall of the chamber. The Isolator Row is typically designed to capture the "first flush" and offers the versatility to be sized on a vol- ume basis or flow rate basis. An upstream manhole not only provides access to the Isolator Row but typically includes a high flow weir such that storm water flowrates or volumes that exceed the capacity of the Isolator Row overtop the overflow weir and discharge through a manifold to the other chambers. The Isolator Row may also be part of a treatment train. By treating storm water prior to entry into the chamber system, the service life can be extended and pollutants such as hydrocarbons can be captured. Pre-treatment best management practices can be as simple as deep sump catch basins, oil -water separators or can be inno- vative storm water treatment devices. The design of the treatment train and selection of pretreatment devices by the design engineer is often driven by regulatory requirements. Whether pretreatment is used or not, the Isolator Row is recommended by StormTech as an effective means to minimize maintenance requirements and maintenance costs. Note: See the StormTech Design Manual for detailed information on designing inlets for a StormTech system, including the Isolator Row. StormTech Isolator Row with Overflow Spillway (not to scale) MANHOLE WITH OVERFLOW WEIR ECCENTRIC HEADER OPTIONAL ACCESS 2 Call StormTech at 888.892.2694 or visit our website at www.stormtech.com for technical and product information. 114 2.0 Isolator Row Inspection/Maintenance StormTech° 2.1 INSIMION The frequency of Inspection and Maintenance varies by location. A routine inspection schedule needs to be established for each individual location based upon site specific variables. The type of land use (i.e. industrial, commercial residential), anticipated pollutant load, per- cent imperviousness, climate, etc. all play a critical role in determining the actual frequency of inspection and maintenance practices. At a minimum, StormTech recommends annual inspec- tions. Initially, the Isolator Row should be inspected every 6 months for the first year of operation. For subsequent years, the inspection should be adjusted based upon previous observation of sediment deposition. The Isolator Row incorporates a combination of standard manhole(s) and strategically located inspection ports (as needed). The inspection ports allow for easy access to the system from the surface, eliminating the need to perform a confined space entry for inspection purposes. If upon visual inspection it is found that sediment has accumulated, a stadia rod should be inserted to deter- mine the depth of sediment. When the average depth of sediment exceeds 3 inches throughout the length of the Isolator Row, clean -out should be performed. 2.2 MAINTENANCE The Isolator Row was designed to reduce the cost of periodic maintenance. By "isolating" sediments to just one row, costs are dramatically reduced by eliminating the need to clean out each row of the entire storage bed. If inspection indicates the potential need for main- tenance, access is provided via a manhole(s) located on the end(s) of the row for cleanout. If entry into the manhole is required, please follow local and OSHA rules for a confined space entries. StormTech Isolator Row (not to scale) CATCH BASIN OR 2FT MIP SUMP 12" MIN ID 25" MAX OD PIPE INSPECTION PORT SET 1.5" FROM BOTTOM LOCATION PER OF CHAMBER ENGINEER'S DRAVA Examples of culvert cleaning noaJes Tpropriate for Isolator Row maintenance. (These aYe not StormTech products.) Maintenance is accomplished with the JetVac process. The JetVac process utilizes a high pressure water noz- zle to propel itself down the Isolator Row while scouring and suspending sediments. As the nozzle is retrieved, the captured pollutants are flushed back into the man- hole for vacuuming. Most sewer and pipe maintenance companies have vacuum/JetVac combination vehicles. Selection of an appropriate JetVac nozzle will improve maintenance efficiency. Fixed nozzles designed for cul- verts or large diameter pipe cleaning are preferable. Rear facing jets with an effective spread of at least 45" are best. Most JetVac reels have 400 feet of hose allow- ing maintenance of an Isolator Row up to 50 chambers long. The JetVac process shall only be performed on StormTech Isolator Rows that have AASHTO class 1 woven geotextile (as specified by StormTech) over their angular base stone. COVER ENTIRE ROW WITH AASHTO M288 CLASS 2 NON -WOVEN GEOTEXTILE SC-740 — 8' WIDE STRIP rSTORMT SC-310-5'WIDESTRIP I ENDCAP WOVEN GEOTEXTILE THAT MEETS AASHTO M288 CLASS 1 REQUIREMENTS, BETWEEN STONE BASE AND CHAMBERS SC-740 — 5'-6'WIDE STRIP SC-310 — 4' WIDE STRIP Call StormTech at 888.892.2694 or visit our website at www.stormtech.com for technical and product information. 3 3.0 Isolator Row step By step Maintenance Procedures Step 1) Inspect Isolator Row for sediment StormTech Isolator Row (not to scale) A) Inspection ports (if present) 1) B) 2 1)A) i. Remove lid from floor box frame ii. Remove cap from inspection riser iii. Using a flashlight and stadia rod, measure depth of sediment and record results on maintenance log. iv. If sediment is at, or above, 3 inch depth proceed to Step 2. If not a proceed to step 3. B) All Isolator Rows i. Remove cover from manhole at upstream end of Isolator Row ii. Using a flashlight, inspect down Isolator Row through outlet pipe 1. Mirrors on poles or cameras may be used to avoid a confined space entry 2. Follow OSHA regulations for confined space entry if entering manhole iii. If sediment is at or above the lower row of sidewall holes (approximately 3 inches) proceed to Step 2. If not proceed to Step 3. Step 2) Clean out Isolator Row using the JetVac process A) A fixed culvert cleaning nozzle with rear facing nozzle spread of 45 inches or more is preferable B) Apply multiple passes of JetVac until backflush water is clean C) Vacuum manhole sump as required Step 3) Replace all caps, lids and covers, record observations and actions Step 4) Inspect & clean catch basins and manholes upstream of the StormTech system Sample Maintenance Log 16 StormTech° Detention • Retention • Recharge Subsurface Stormwater Management'm 20 Beaver Rbai,Suite 104 V%thasfidd I ODnnedioLd 106109 860.529.8188 1888.892.2694 fac866.328.8401 I wA !staiTtech.mm StormTech products arecovaed by one or mDre of the fd low ng patents: US PatErds 5,401,459; 5,511,903; 5,716,163; 5,588,778; 5,839,844; Canadian PAEnts: 2,158,418 Ctha- U.S. end Fa-agn Pdents PrxiingRinted in USA © Copyright. AI rights reserved. StormTech LLQ 2004 3090104-1 Appendix G Supporting Documentation -... ��!- .l i+} �• Y,4 '-x�'S 1 i `�$` -u��+` '�" Sri t•"`•'` _ . i ems. X�;-- 627C. lkmm s �`t _.ate. ..ti •' .; f• , Af ': i S� 2Eli 6l�_ off: ML IV Be � s �r MAP LEGEND Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons A 0 Soil Map Unit Lines 0 Soil Map Unit Points Special Point Features {j Blowout Borrow Pit Clay Spot 0 Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Ig Rock Outcrop + Saline Spot Sandy Spot 4g, Severely Eroded Spot Sinkhole x, Slide or Slip jo Sodic Spot Soil Map —Middlesex County, Massachusetts MAP INFORMATION Spoil Area The soil surveys that comprise your AOI were mapped at 1:25,000. Stony Spot Warning: Soil Map may not be valid at this scale. Very Stony Spot Enlargement of maps beyond the scale of mapping can cause S7 Wet Spot misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting Other soils that could have been shown at a more detailed scale. Special Line Features Please rely on the bar scale on each map sheet for map Water Features measurements. Streams and Canals Source of Map: Natural Resources Conservation Service Transportation Web Soil Survey URL: http://websoilsurvey.nres.usda.gov r-++ Rails Coordinate System: Web Mercator (EPSG:3857) Interstate Highways Maps from the Web Soil Survey are based on the Web Mercator US Routes projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Major Roads Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. Local Roads This product is generated from the USDA-NRCS certified data as of Background the version date(s) listed below. . Aerial Photography Soil Survey Area: Middlesex County, Massachusetts Survey Area Data: Version 12, Feb 26, 2010 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Mar 30, 2011—May 1, 2011 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. uSDA Natural Resources Web Soil Survey 8/22/2013 Conservation Service National Cooperative Soil Survey Page 2 of 3 Soil Map —Middlesex County, Massachusetts Map Unit Legend Middlesex County, Massachusetts (MA017) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 602 Urban land 57.0 85.7% 627C Newport -Urban land complex, 3 to 15 percent slopes 9.5 14.3% 100.0% Totals for Area of Interest 66.5 LJSDA Natural Resources Web Soil Survey 8/22/2013 Conservation Service National Cooperative Soil Survey Page 3 of 3 SANBORN III HEAD Building Dust. Bngin eering Success. MEMORANDUM To: Nate Cheal, P.E. — Tetra Tech From: Vern Kokosa, P.E. and Amy Blomeke — Sanborn Head File: 3516.00 Date: September 19, 2013 Re: Rawls Rate for Proposed Infiltration Chambers Proposed Residential Development - Arsenal Street Watertown, Massachusetts cc: Tom Denney — Hanover Company Sanborn, Head & Associates, Inc. (Sanborn Head) has prepared this memorandum to convey estimated Rawls Rate infiltration design criteria based on available subsurface information collected to date. Based on our understanding of the project at this time, we understand that stormwater infiltration chambers are proposed below the parking garage area shown on the attached figure. Stormwater infiltration chambers are anticipated to be placed between garage footings, but proposed infiltrations depths have not been determined at this time. Sanborn Head has performed numerous exploration programs across the site since 2010. A total of seven (7) explorations have been performed within the footprint of the proposed parking garage. Explorations have include five (5) Geoprobe direct -push borings and two (2) geotechnical test borings, one of which was completed as a 2-inch diameter PVC groundwater monitoring well. Groundwater was observed approximately at Elevation 22 (NAVD 88) at boring SH-122W, based on stabilized groundwater levels measured in January 2011 and 2013. Logs of the borings are attached. Based on the visual field classifications from drilling activities, Sanborn Head has assigned a textural soil class for each soil stratum encountered in the test borings using the Natural Resources Conservation Service (NRCS) Textural Classification System. From the NRCS Texture Class, a soil group and Rawls infiltration rate are then assigned, as outlined in the Massachusetts Stormwater Handbook. The results of the texture classification and corresponding Rawls rates are shown in the following table. SANSORN. HEAD & ASSOCIATES. INC. www.sanbcrnheadxom September 19, 2013 20130919 Rawls Rate Memo.docx Page 2 3516.00 Boring ID Stratum Depth' feet MRCS Texture ClaSS2 MRCS Soil Groups Infiltration Rate4 in hr SH-103 4.0-9.1 Loamy Sand A 2.41 SH-103 9.1-21.1 Sandy Loam B 1.02 SH-122W 4.0-8.0 Loamy Sand A 2.41 SH-122W 8.0-19.0 Sand A 8.27 SH-GP-2 3.5-8.0 Sand A 8.27 SH-GP-3 4.0-10.0 Sand A 8.27 SH-GP-3 10.0-15.0 Loamy Sand A 2.41 SH-GP-5 5.0-15.0 Loamy Sand A 2.41 SH-GP-7 5.0-9.4 Loamy Sand A 2.41 SH-GP-7 9.4-15.0 Loamy Sand A 2.41 SH-GP-8 4.5-7.6 Loamy Sand A 2.41 SH-GP-8 7.6-15.0 Sand A 8.27 Notes: 1. See exploration logs by Sanborn Head for further observations made during drilling and soil descriptions. 2. Natural Resources Conservation Service (NRCS) Texture Classifications are based on the texture triangle and particle -size limits; see USDA, NRCS, 2007 National Soil Survey Handbook, Part 618, Exhibit 8. 3. NRCS Soil Groups are taken from the Hydrology National Engineering Handbook, Part 630, Chapter 7. Hydrological Soil Groups. 4. Infiltration rates are the 1982 Rawls Rates defined in the Massachusetts Stormwater Handbook, Table 2.3.3. Based on the data available, the soils below the parking garage area are considered Sandy Loam, Loamy Sand and Sand. The infiltration rate used for preliminary design will depend on the location and depth selected for the proposed chambers. As no field infiltration tests have been completed at the site, a Rawls Rate in the range of 1.0 to 2.4 in/hour is suggested for the preliminary design of the proposed stormwater infiltration chambers. When a preliminary garage foundation plan becomes available, we will assist you with infiltration chamber layout and design. Encl. Exploration Location Plan Exploration Logs by Sanborn Head \\wesservl\DataShare\DATA\WESDATA\3500\3516.00\Source Files\Infiltration Memo\20130919 Rawls Rate Memo.docx SANBORN HEAD Bar Measures 1 inch Description and Classification of Soil 1. Density or Consistency: The density or consistency of a soil sample is based on the Standard Penetration Test N-value according to the following table: Density of Granular Soil SPT N-Value Consistency of Cohesive Soil Very Loose 0-4 <2 Very Soft Loose 4-10 2-4 Soft Medium Dense 10-30 4-8 Medium Stiff Dense 30-50 8-15 j Stiff Very Dense >50 15-30 Very Stiff >30 Hard The Standard Penetration Resistance, or N-value in blows per foot, is the sum of the blows recorded over the second and third 6-inch interval. A number followed by "/3" indicates the distance that the sampler advanced. For example "100/4" indicates that 100 blows of a 140 pound hammer falling 30 inches advanced the sampler 4 inches. "WOR/24" indicates the weight of the drilling rods without the hammer caused the sampler to advance 24 inches. "WOH" indicates the static weight of the 140 pound hammer and the drilling rods attached to the split spoon sampler were sufficient to cause the sampler to advance. "WOR" indicates the static weight of the drilling rods attached to the split spoon sampler was sufficient to cause the sampler to advance. 2. Color: The color of a soil sample is based on visual observation. 3. Soil Components A. Description: The components of a soil sample are described by visually estimating the percentage of each component by weight of the total sample using a Modified Bannister System. i. Major Component: The major soil component is written with upper case letters for granular soil (e.g., SAND, GRAVEL) and a combination of upper and lower case letters for fine grained soil (e.g., Silty CLAY, Clayey SILT). ii. Minor Component: The minor soil components are written with the first letter of each soil type in upper case, and the remaining letters in lower case (e.g., Gravel, Silt). The minor components are identified and prefaced in the description based on the following percentages: Preface Percentage and 35-50 some 20-35 little 10-20 trace 0-10 iii. Note: The actual percentages of gravel soil may differ from that measured when sampling with a standard split spoon sampler because of the relatively small sampler diameter. Also, it is not possible to identify the presence of boulders and cobbles using a standard split spoon sampler. B. Definitions i. Granular Soil: A granular soil sample is defined by the following particle sizes as referenced to a standard sieve: Material Description Standard Sieve Limit Upper Lower Boulders C-sized 36 inch B-sized 36 inch 24 inch A -sized 24 inch 12 inch Cobbles 12 inch 3 inch Gravel coarse 3 inch 3/4 inch fine 3/4 inch No.4 Sand coarse No.4 No. 10 medium No. 10 No.40 fine No.40 No.200 ii. Fine Grained Soil: The degree of plasticity of fine-grained soils is aennea as rouows: Material Degree of Plasticity Plasticity Index (PI) Smallest Thread Diameter (in.) SILT Non -Plastic 0 None Clayey SILT Slight 1 to 5 1/4 SILT & CLAY Low 5 to 10 1/8 CLAY & SILT Medium 10 to 20 1/16 Silty CLAY High 20 to 40 1/32 CLAY Very High 40+ 1/64 iii. Organic Soil: An organic soil sample is classified by observation of the sample structure as follows: Material Description TOPSOIL Surficial soils that support plant life and which contain organic matter. SUBSOIL Soil underlying the topsoil which may contain very fragments of plant fibers. PEAT Deposits of plant remains in which the original plant fibers may be visible. Deposit of plant remains in which the ORGANIC SILT original plant fibers have been destroyed, may have high sand content. Usually found underlying peat. iv. Non -Soil Constituents : Non -soil constituents (artificial or anthropogenic material, organic materials, cobbles and boulders) are described as follows: The following terminology is used to denote size ranges of non -soil constituents: Descriptive Term Size Range Comparative Term Specks <No. 200 Sieve Silt and Clay fines Particles No. 200 Sieve to No. 4 Sieve Sand Fragments No. 4 Sieve to 3 in. Gravel Pieces 3 in. to 12 in. Cobbles Blocks > 12 in. Boulders The following terminology is used to describe the frequency that a non -soil constituent is observed by estimating the percentage of the constituent by weight of the total sample: Descriptor Percentage very few 0-5 few 5-10 common 10-20 frequent 20-35 numerous 35-50 4. Moisture Content: The moisture content of a soil sample is based on the observable presence of water according to the following table: Dry Moisture is not apparent, dusty. Moist No visible water. Wet Visible free water. 5. Other Pertinent Characteristics : Pertinent characteristics observed in a soil sample should be noted according to the following table: Soil Structure Produced by Deposition of Sediments Stratified Random soil deposits of varying components of color. Varved Alternating soil deposits of varying thickness (i.e., clays or silts). Stratum Soil deposit > 12 inches thick. Layer Soil deposit 3 inches to 12 inches thick. Seam Soil deposit 1/8 inch to 3 inches thick. Parting/Lens I Soil deposit <1/8 inch thick. (c) 2011 Sanborn, Head & Associates, Inc. Boring / Monitoring Well Log Legend Project: Industrial Site Redevelopment Log of Monitoring Well SH-1 SAN BORN Location: Anytown, State SHA Project No.: 1234.56 Ground Elevation: 112.2 feet TOC Elevation: 115.2 feet PVC Elevation: 115.10 feet Drilling Method: Mobile B-53 Truck, 5" PW Drive & Wash Datum: MSL Sampling Method: 2" O.D. Split Spoon w/140 lb Safety Groundwater Readings Hammer Depth Depth Depth Stab. Drilling Company: Ground Down Drilling Co. Date Time to Water Ref. Pt. of Casing of Hole Time Foreman: J. Driller 06/24/08 09:45 10.0' Ground 27' 27' <5 min Date Started: 06/25/08 Date Finished: 06/26/08 06/25/08 14:50 12.0' Top of PVC Well Installed 50' 15 min Logged By: A. Engineer Checked By: A. Principal 07/03/08 13:00 12.2' Top of PVC Well Installed 50' 8 days CasingI ll Sample Information Stratum ft) glows Rate Sample Depth Spoon Pen/ Field Geologic Description Well Well Description (perft) (min/ft) No. (ft) Blows Rec Testing Log Description Diagram per 6 in in Data 1 2 3 4 5 6 7 8 9 9 10 11 11 1. The numbers in this column report the depth in feet below ground surface. 2. The numbers in this column report the number of blows required to drive the drill casing one foot using a 300 pound hammer, unless otherwise specified. 3. The numbers in this column report the rate of advance when coring rock. 4. The values in this column report the sample designation. In the example S-1, "S" indicates the sample type and "1" indicates the sample number. "S" indicates split spoon sample "C" indicates rock core sample "U" indicates Shelby tube sample "Go indicates grab sample 5. The numbers in this column report the depth, in feet, from the ground surface of the sample identified in column. 6. The numbers in this column report the number of blows required to drive a split spoon sampler 6 inches using a 140 pound hammer free falling 30 inches. The standard split spoon sampler is 1-3/8 inch inside diameter and 2 inches outside diameter. The Standard Penetration Resistance, or N-value in blows per foot, is the sum of the blows recorded over the second and third 6-inch interval. A number followed by "/3" indicates the distance that the sampler advanced. For example "100/4" indicates that 100 blows of a 140 pound hammer falling 30 inches advanced the sampler 4 inches. "WOR/24" indicates the weight of the drilling rods without the hammer caused the sampler to advance 24 inches. "WOH" indicates the static weight of the 140 pound hammer and the drilling rods attached to the split spoon sampler were sufficient to cause the sampler to advance. "WOR" indicates the static weight of the drilling rods attached to the split spoon sampler was sufficient to cause the sampler to advance. 7. The values shown are the length of the soil or rock core sampler penetration and the number of inches of sample recovered from the sampler. 8. The values shown are the results of field tests performed on soil or rock samples. The test method, result and units are indicated. Unless otherwise noted "ND" denotes not detected. 9. These columns provide a graphic illustration and verbal description of the subsurface soil and rock strata. The depths of strata changes should be considered approximate and general in nature, actual strata changes in the field may be more gradual. 10. Descriptions of soil samples include: the density or consistency; color; a listing of MAJOR and minor soil components based on particle size and plasticity; structure, moisture; and other pertinent characteristics. For example: Medium dense, brown, fine to medium SAND, trace Silt. Stratified. Moist. Faint petroleum odor. Description of rock core samples include: - hardness, weathering, rock continuity, color, texture, rock type, structure; and RQD (%) For example: Hard to Very Hard, slightly weathered, moderately fractured, grey -green, fine grained, RHYOLITE, with joints spaced 4 to 12 inches apart and dipping from near horizontal to approximately 60°. Open crack in core at 14.4'. moderately fractured . RQD=58% NOTE: "RQD" is defined as the summation of all pieces of rock core greater than 4 inches in length divided by the length of the core run and expressed as a percentage. 11. Monitoring well materials or other equipment installed within the borehole are graphically presented in these columns. If no equipment was installed, these columns are used for notes, remarks or other pertinent observations. (c) 2011 Sanborn, Head & Associates, Inc. 0 0 w x z W 0 m a 0 N m cJa LU 0 a x 0 ,n a 0 0 N Project: Arsenal St. Log Of Boring SH-103 SANBORN III HEAD Location: Watertown, MA Ground Elevation: 30.0±feet Project No.: 3215.00 Datum: NGVD 1929 Sanborn, Head & Associates, Inc. Drilling Method: Diedrich D-120 Truck, 4%" ID Hollow Stem Augers Sampling Method: 2" O.D. Split Spoon, Auto Hammer Groundwater Readings Depth Depth Depth Stab. Date Time to Water Ref. Pt. of Casing of Hole Time Drilling Company: Crawford Drilling Services, LLC 01/14/11 08:30 17.95' Ground Surface 23' 5 min. Foreman: J. Thibault Date Started: 01/14/11 Date Finished: 01/14/11 Logged By: A. Larrabee Checked By: M. Heil Sample Information Stratum Depth (ft) Geologic Description g p Remarks Sample Depth Spoon Pen/ Field No. (ft) glows Rec Testing Log Description er 6 in in Data 0 0 • • -, Asphalt. ` S-1 (0.5 to 2'): Medium dense, brown, fine to coarse S-1 0.5 - 2 22 18/14 15 SAND, little Gravel, little Silt, few Brick fragments. 13 I Moist. FILL. 2 S-2 2-4 12 24/14 ` FILL S-2 (2 to 4'): Medium dense, brown, fine SAND, little 11 Gravel, little Silt, few Glass fragments, few Brick 11 I fragments. Moist. FILL. 11 ` I S-3 4-6 5 24/16 i _____ S-3A (4 to 4.9'): Medium dense, brown, fine to 3 coarse SAND, little Silt, trace Gravel. Moist. 7 8 S-36 (4.9 to 6'): Medium dense, light brown, fine to coarse SAND, little Silt, trace Gravel. Moist. 6 S-4 6-8 12 24/12 S-4 (6 to 8'): Medium dense, light brown, fine to 10 SAND coarse SAND, little Gravel, trace Silt. Moist. 12 18 8 S-5 8-10 4 24/14 S-5A (8 to 9.1'): Loose, light brown, fine to coarse 3 SAND, some Silt, trace Gravel. Wet. 4 4 S-56 (9.1 to 10'): Loose, light brown, fine to medium SAND, little Silt. Wet. 10 S-6 10-12 6 24/15 S-6 (10 to 12'): Medium dense, light brown, fine to 6 medium SAND, some Silt. Wet. 9 13 12 14 ' SILTY SAND S-7 15 - 17 5 24/24 3 S-7 (15 to 17'): Medium dense, light brown, fine to 5 coarse SAND, little Silt. Wet. 10 16 11 18 Sheet: 1 of 2 c� 0 a w x z W 0 m z 0 0 N 0] J i 0 a w x z O ,n z Cn 0 0 N Project: Arsenal St. Log Of Boring SH-103 SANBORN III HEAD Location: Watertown, MA Ground Elevation: 30.0±feet Project No.: 3215.00 Datum: NGVD 1929 Sanborn, Head & Associates, Inc. Drilling Method: Diedrich D-120 Truck, 4%" ID Hollow Stem Augers Sampling Method: 2" O.D. Split Spoon, Auto Hammer Groundwater Readings Depth Depth Depth Stab. Date Time to Water Ref. Pt. of Casing of Hole Time Drilling Company: Crawford Drilling Services, LLC 01/14/11 08:30 17.95' Ground Surface 23' 5 min. Foreman: J. Thibault Date Started: 01/14/11 Date Finished: 01/14/11 Logged By: A. Larrabee Checked By: M. Heil Sample Information Stratum Depth (ft) Geologic Description g p Remarks Sample Depth Spoon Pen/ Field No. (ft) glows Rec Testing Log Description er 6 in in Data 20 S-8 20 - 22 6 24/19 S-8A (20 to 21.1'): Dense, light brown, fine to 8 SILTY SAND medium SAND, some Silt. Wet. 35 41 21.1'----- S-86 (21.1 to 22'): Dense, light brown, SILT, some o• Gravel, trace Sand. Wet. TILL. 22 Q o• TILL 23 Boring terminated at 23 ft. due to auger refusal. 24 26 28 30 32 34 36 38 An Sheet: 2 of 2 0 0 w x z W 0 ca co LU N cJa 0 a x 0 z Q 0 0 N Project: Arsenal St. Log of Monitoring Well SH-122W SANBORN III HEAD Location: Watertown, MA Ground Elevation: 29.45 feet Project No.: 3215.00 TOC Elevation: 29.44 feet Sanborn, Head & Associates, Inc. PVC Elevation: 28.96 feet Drilling Method: Diedrich D-120 Truck, 4%4" ID Hollow Stem Augers Datum: NGVD 1929 Sampling Method: 2" O.D. Split Spoon, Auto Hammer Groundwater Readings Depth Depth Depth Stab. Date Time to Water Ref. Pt. of Casing of Hole Time Drilling Company: Crawford Drilling Services, LLC 01/10/11 16:05 7.75' Top of PVC Well Installed <15 min. Foreman: T. Martinelli Date Started: 01/10/11 Date Finished: 01/10/11 Logged By: L. Norton Checked By: M. Heil Sample Information Stratum DepthSample Geologic Description Diag�lem Well Description le Depth Spoon / Field No. Bows Rec— Testing Log Description er 6 in in Data 0 0 ----0.3------ 2" Dia. Flushmounted • • Asphalt. S-1 (0.5 to 2'): Loose, black, SILT, little Sand, trace S-1 0.5-2 9 18/14 PID: 0.6 Road Box with Locking J-Plug Set in Concrete (0 4 ppmv I Gravel. trace Roots Moist. FILL. to 0.5') 4 i Cuttings (0.5 to 1.5') 2 S-2 2-4 4 24/13 PID: 0.3 I FILL S-2 (2 to 4'): Loose, black, SILT, little Sand, trace ite Chip Seal (1.5 3 ppmv I Gravel. trace Roots Moist. FILL. to3') to 3') ' 2 2 2" Dia. Sch. 40 PVC Riser I (0.5 to 4.4') 4 S-3 4-6 3 24/14 PID: 0.2 i 4 S-3 (4 to 6'): Very loose, brown, fine to medium 1 ppmv SAND, little Silt. Moist. 1 3 6 S-4 6-8 7 24/20 PID: 0.7 SILTY SAND S-4 (6 to 8'): Dense, brown with orange, fine to 12 ppmv medium SAND, little Silt, trace Gravel. Moist. 20 25 8 S-5 8-10 17 24/14 PID: ND 8 S-5 (8 to 10'): Dense, brown, fine to coarse SAND, 20 trace Gravel, trace Silt. Wet. 28 30 Sand (3 to 155) 2" Dia. Sch. 40 PVC Well 10 Screen (0.010" Slots) (4.4 S-6 10 - 12 10 24/10 PID: ND S-6 (10 to 12'): Dense, brown, fine to coarse SAND, to 14.4') 14 trace Gravel, trace Silt. Wet. 26 15 12 SAND 14 2" Dia. Sch. 40 PVC Conical End Cap (14.4 to S-7 15-17 9 24/17 PID: ND S-7 (15 to 17'): Medium dense, light brown, fine to 14.6') 3 coarse SAND, little Silt. Wet. 8 16 15 18 SAND & •. GRAVEL Sheet: 1 of 2 0 a w x z W 0 z U) 0 0 N m cJa 0 a w x z 0 ,n z Cn 0 0 N Project: Arsenal St. Log of Monitoring Well SH-122W SANBORN III HEAD Location: Watertown, MA Ground Elevation: 29.45 feet Project No.: 3215.00 TOC Elevation: 29.44 feet Sanborn, Head & Associates, Inc. PVC Elevation: 28.96 feet Drilling Method: Diedrich D-120 Truck, 4%4" ID Hollow Stem Augers Datum: NGVD 1929 Sampling Method: 2" O.D. Split Spoon, Auto Hammer Groundwater Readings Depth Depth Depth Stab. Date Time to Water Ref. Pt. of Casing of Hole Time Drilling Company: Crawford Drilling Services, LLC 01/10/11 16:05 7.75' Top of PVC Well Installed <15 min. Foreman: T. Martinelli Date Started: 01/10/11 Date Finished: 01/10/11 Logged By: L. Norton Checked By: M. Heil Sample Information Stratum DepthSample Geologic Description Diag�lem Well Description le Depth Spoon / Field No. Bows Rec— Testing Log Description er 6 in in Data 20 S-8 20 - 22 12 24/22 PID: ND .'• S-8 (20 to 22'): Medium dense, brown, GRAVEL, 12 little Sand, trace Silt. Wet. 9 .. 10 •,!- SAND & GRAVEL Cuttings (15.5 to 2T) 22 .. ----- 22------ 24 SAND S-9 25 - 27 5 24/23 PID: ND S-9 (25 to 26.3'): Medium dense, light brown, fine to 11 medium SAND, some Silt. Wet. 9 26 9 27 Boring terminated at 27 ft. No refusal encountered. 28 NOTES: 1. Soil samples were screened for volatile organic compounds (VOCs) using a Photovac Model 2020 Photoionization Detector (PID) with a 10.6 eV lamp, calibrated to a 100 parts per million by volume (ppmv) isobutylene-in-air standard using a response factor of 1.0. Results are presented in ppmv; the 30 typical detection limit is 1 ppmv. ND indicates not detected. 2. Soil sample taken from 6 to 8 ft. to be submitted for environmental laboratory analysis. 3. Blowing sands encountered at 14 ft. 32 34 36 38 An Sheet: 2 of 2 C7 0 w x z W 0 z U) 0 N 0] J c� 0 a w x z O ,n z Cn 0 0 N Project: Arsenal St. Log of Boring SH-GP-02 SANBORN III HEAD Location: Watertown, MA Ground Elevation: 33.0±feet Project No.: 3215.00 Datum: NGVD 1929 Sanborn, Head & Associates, Inc. Drilling Method: Geoprobe® 661ODT Track Rig Sampling Method: MacroCore® Sampler, 5 ft. dual tube Groundwater Readings Depth Depth Depth Stab. Date Time to Water Ref. Pt. of Casing of Hole Time Drilling Company: Crawford Drilling Services, LLC 01/07/11 --- No Groundwater Encountered 5 min. Foreman: A. Allen Date Started: 01/07/11 Date Finished: 01/07/11 Logged By: A. Larrabee Checked By: M. Heil Sample Information Stratum Depth (ft) Geologic Description Remarks S le DepthRec Pen/ Field No. Testing Log Description ft Data S-1 0-5 5.0/ --- ? `°: Concrete slab. 1.8 PID: ND 0'7 S-1A (0.7 to 35): Dark brown, fine to coarse SAND, little Gravel, trace Silt. Moist. FILL. I 2 / I FILL I PID: ND ;:: ; -3.5 S-16 (3.5 to 5'): Light brown, fine to coarse SAND, some 4 Gravel, trace Silt. Moist. S-2 5-8.8 3.8/ S-2A (5 to 7'): Light brown, fine to coarse SAND, little Gravel, 2.4 trace Silt. Moist. 6 SAND S-213 (7 to 8.8'): Light brown, fine to coarse SAND, trace Silt. Moist. 8 (Cobble in tip of MacroCore.). 8.8 Boring terminated at 8.8 ft. due to Geoprobe refusal. NOTES: 10 1. Surrounding floor drain depth: 2.6 feet. 2. Soil samples taken from 3.5 to 5 feet and 7 to 8.8 feet to be submitted for environmental laboratory analysis. 12 14 16 18 Sheet: 1 of 1 0 0 w x z W 0 z U) 0 N m C7 LU 0 a x 0 z Q 0 0 N Project: Arsenal St. Log of Boring SH-GP-03 SANBORN III HEAD Location: Watertown, MA Ground Elevation: 33.0±feet Project No.: 3215.00 Datum: NGVD 1929 Sanborn, Head & Associates, Inc. Drilling Method: Geoprobe® 661ODT Track Rig Sampling Method: MacroCore® Sampler, 5 ft. dual tube Groundwater Readings Depth Depth Depth Stab. Date Time to Water Ref. Pt. of Casing of Hole Time Drilling Company: Crawford Drilling Services, LLC 01/07/11 --- 14' Ground Surface 15' 5 min. Foreman: A. Allen Date Started: 01/07/11 Date Finished: 01/07/11 Logged By: A. Larrabee Checked By: M. Heil Sample Information Stratum Depth (ft) Geologic Description Remarks S le epth Pen/ Field No. Rec Testing Log Description ft Data S-1 0-5 5.0/ --- ? `': Concrete Slab. 2.6 PID: ND 0'7 S-1A (0.7 to 4'): Dark brown, fine to coarse SAND, some Gravel, trace Silt. Moist. FILL. I 2 i FILL I I 4 PID: ND ;:; :; 4 S-1B (4 to 5'): Light brown, fine to coarse SAND, little Gravel, little Silt. Moist. S-2 5-10 5.0/ PID: ND S-2 (5 to 10'): Light brown, fine to coarse SAND, little Gravel, 3.1 trace Silt. Moist. 6 8 SAND 10 S-3 10-15 5.0/ PID: ND ? S-3A (10 to 12.8'): Light brown, fine to coarse SAND, trace 2.8 Gravel, trace Silt. Moist. 12 ' PID: ND ' S-313 (12.8 to 14'): Light brown, fine to coarse SAND, trace Gravel, trace Silt. Moist. 14 PID: ND S-3C (14 to 16): Light brown, fine to medium SAND, little Silt. Wet. -----15------ Boring terminated at 15 ft. No refusal encountered. 16 NOTES: 1. Surrounding floor drain depth: 2.3 feet. 2. Soil samples taken from 0 to 5 feet and 5 to 10 feet to be submitted for environmental laboratory analysis. 18 Sheet: 1 of 1 0 0 w x z W 0 z U) 0 0 N m LU a x 0 z Q 0 0 N Project: arsenal St. Log of Boring SH-GP-05 SANBORN III HEAD Location: Watertown, MA Ground Elevation: 33.0±feet Project No.: 3215.00 Datum: NGVD 1929 Sanborn, Head & Associates, Inc. Drilling Method: Geoprobe® 661ODT Track Rig Sampling Method: MacroCore® Sampler, 5 ft. dual tube Groundwater Readings Depth Depth Depth Stab. Date Time to Water Ref. Pt. of Casing of Hole Time Drilling Company: Crawford Drilling Services, LLC 01/06/11 --- 12' Ground Surface 15' 5 min. Foreman: A. Allen Date Started: 01/06/11 Date Finished: 01/06/11 Logged By: A. Larrabee Checked By: M. Heil Sample Information Stratum Depth (ft) Geologic Description Remarks S le DepthRec Pen/ Field No. Testing Log Description ft Data 0 S-1 0-5 5.0/ 0 CONCRETE ? `': .9..A. Concrete Slab. 12 0'5 S-1 (0.5 to 5'): Brown, fine to coarse SAND, some Gravel, little PID: ND i \ I Silt. Moist. FILL. 2 i I i I FILL I 4 i I S-2 5-10 5.0/ PID: ND i A- ; -5 S-2A (5 to 8.2'): Dark brown, fine to coarse SAND, some 4.0 Gravel, little Silt. Moist. 6 8 PID: ND S-213 (8.2 to 10'): Light brown, fine to coarse SAND, little Gravel, little Silt. Moist. 10 S-3 10-15 5.0/ PID: ND SAND S-3 (10 to 15'): Light brown, fine to coarse SAND, little Silt, 2.9 trace Gravel. Moist to wet. 12 14 -----15------ Boring terminated at 15 ft. No refusal encountered. 16 NOTES: 1. Surrounding floor drain depths: 1.7 feet and 2.1 feet. 2. Soil samples taken from 0 to 5 feet and 8.2 to 10 feet to be submitted for environmental laboratory analysis. 18 Sheet: 1 of 1 0 0 w x z W 0 ca 0 N m LU a x 0 z Q 0 0 N Project: Arsenal St. Log of Boring SH-GP-07 SANBORN III HEAD Location: Watertown, MA Ground Elevation: 33.0±feet Project No.: 3215.00 Datum: NGVD 1929 Sanborn, Head & Associates, Inc. Drilling Method: Geoprobe® 661ODT Track Rig Sampling Method: MacroCore® Sampler, 5 ft. dual tube Groundwater Readings Depth Depth Depth Stab. Date Time to Water Ref. Pt. of Casing of Hole Time Drilling Company: Crawford Drilling Services, LLC 01/06/11 11:48 11.1' Ground Surface 15' 5 min. Foreman: A. Allen Date Started: 01/06/11 Date Finished: 01/06/11 Logged By: A. Larrabee Checked By: M. Heil Sample Information Stratum Depth (ft) Geologic Description Remarks S le DepthRec Pen/ Field No. Testing Log Description ft Data S-1 0-5 5.0/ --- v .r. Concrete slab. 1.7 PID: ND -0.4 S-1A (0.4 to 3.4'): Dark brown, fine to coarse SAND, little Silt. \ i I Moist. FILL. 2 i I FILL PID: ND I S-113 (3.4 to 4.4'): Light brown, fine to coarse SAND, some i Gravel, trace Silt. Moist. FILL. 4 PID: ND I 4.4 S-IC (4.4 to 5'): Dark brown, fine to coarse SAND, little Silt, PEAT trace Organics. Moist. PEAT. S-2 5-10 5.0/ PID: ND 5 S-2A (5 to 8'): Brown, fine to coarse SAND, trace Gravel, trace 3.0 Silt. Moist. 6 8 PID: ND S-26 (8 to 8.2'): Dark brown, fine to coarse SAND, little Silt, PID: ND very few Root fibers. S-2C (8.2 to 9A): Light brown, fine to medium SAND, little Silt. Moist. PID: ND S-2D (9.4 to 10'): Light brown to gray, fine to coarse SAND, some Gravel, trace Silt. Moist. 10 S-3 10-15 5.0/ PID: ND SAND S-3A (10 to 12.6'): Light brown to gray, fine to coarse SAND, some Gravel, trace Silt. Moist. 12 PID: ND S-36 (12.6 to 13.3'): Light brown, fine to coarse SAND, little Gravel, trace Silt. Moist. PID: ND S-3C (13.3 to 15'): Light brown, fine to coarse SAND, little Gravel, trace Silt. Wet. 14 -----15------ Boring terminated at 15 ft. No refusal encountered. 16 NOTES: 1. Soil sample taken from 8.2 to 10 feet to be submitted for environmental laboratory analysis. 18 Sheet: 1 of 1 0 c? w x z W 0 z w 0 0 N m x z W m a 0 0 N Project: Arsenal St. Log of Boring SH-GP-08 SANBORN 1111 HEAD Location: Watertown, MA Ground Elevation: 33.0±feet Project No.: 3215.00 Datum: NGVD 1929 Sanborn, Head & Associates, Inc. Drilling Method: Geoprobe® 661ODT Track Rig Sampling Method: MacroCore® Sampler, 5 ft. dual tube Groundwater Readings Depth Depth Depth Stab. Date Time to Water Ref. Pt. of Casing of Hole Time Drilling Company: Crawford Drilling Services, LLC 01/06/11 14:25 11.1' Ground Surface 15' 5 min. Foreman: A. Allen Date Started: 01/06/11 Date Finished: 01/06/11 Logged By: A. Larrabee Checked By: M. Heil Sample Information Stratum Depth (ft) Geologic Description Remarks S le D(ft)h Pen/ Field No. Rec Testing Log Description ft Data 0 S-1 0-5 5.0/ ?` 9' 0 Concrete slab. 1.6 `. CONCRETE PID: ND 0'7 S-1A (0.7 to 4.2'): Light brown, SILT & CLAY, little Gravel. Moist. FILL. \ I 2 \i I i FILL I I 4 PID: ND \ _ S-1 B (4.2 to 4.5'): Dark brown, fine to medium SAND, some PID: ND Silt. Moist. FILL. S-2 5-10 5.0/ PID: ND PID: ND ~' 4 5 S-1C to 4.6' Li ( ): Light g brown, fine to coarse SAND, little 3.0 ;;:; Gravel, little Silt. Moist. S-1 D (4.6 to 5'): Brown, fine to medium SAND, little Gravel, 6 "; trace Silt. Moist. ri.. S-2A (5 to 7.2'): Light brown, fine to coarse SAND, little Gravel, trace Silt. Moist. PID: ND i';' S-213 (7.2 to 7.6'): Brown, fine to coarse SAND, some Gravel, PID: ND trace Silt. Moist. 8 S-2C (7.6 to 8'): Dark brown, fine to coarse SAND, little Silt. PID: ND Moist. S-21D (8 to 10'): Brown, fine to medium SAND, trace Silt. Moist. ' SAND 10 S-3 10-15 5.0/ PID: ND ''`:' S-3A (10 to 112): Light brown to gray, fine to coarse SAND, 4.0 y� little Gravel, trace Silt. Moist. PID: ND S-313 (11.2 to 16): Light brown, fine to medium SAND, little �•' Silt. Wet. 12 ' y� 14 y.� 4� ---15'----- Boring terminated at 15 ft. No refusal encountered. 16 NOTES: 1. Surrounding floor drain not opened. 2. Soil sample taken from 0 to 5 feet and 8 to 10 feet to be submitted for environmental laboratory analysis. 18 Sheet: 1 of 1 2006 EDITION Exhibit 8-12 Intensity - Duration - Frequency Curve for Boston, MA Source: TR55 - Urban Hydrology for Small Wetlands, NRCS January 2006 Drainage and Erosion Control 8-27