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HomeMy Public PortalAboutPlanning Board Packet 07/26/23APPROVAL NOT REQUIRED, CASE NO. 2023-07 APPLICANT/OWNER: JODIE CASH-EDDY & ROBERT AND CHERYL DOLAN PROPERTY: 23 AND 33 FRANKLIN CARTWAY Date: July 18, 2023 To: Planning Board From: Jon Idman, Town Planner Re: Approval Not Required Plan Endorsement: PB#2023-07 23 Franklin Cartway (Map 50 Pcl 11), Jodie Cash- Eddy, Trustee, Owner 33 Franklin Cartway (Map 50 Pcl 12), Robert Dolan and Cheryl Dolan, Trustees, Owner _____________________________________________________________________________________ Staff Recommendation Vote to endorse the plan entitled “Plan of Land, 23 & 33 Franklin Cartway in Brewster, Massachusetts (Barnstable County), Approval Not Required Plan,” prepared for Jodie Cash-Eddy by The BSC Group, Inc., West Yarmouth, MA, dated and stamped July 11, 2023 by Kieran J. Healy, PLS for The BSC Group, as it does not depict a subdivision and thus does not require approval under the subdivision control law. Discussion The respective owners of 23 & 33 Franklin Cartway have submitted a plan of land to the Board for endorsement which shows a division of a portion of 33 Franklin Cartway to add/ convey to the abutting lot at 23 Franklin Cartway. It appears that the purpose of the division is for conveyancing purposes to increase the size of the 23 Franklin Cartway lot, which is small and oddly shaped, with an existing building occupying a majority of it. Both lots are improved with buildings and other development. The plan submitted to the Board is styled as an “Approval Not Required” (ANR) plan per MGL Ch. 41 ss. 81L & 81P and Section 290-4 of the Brewster Subdivision Rules and Regulations; the owner/ applicants maintain that no subdivision approval is required for the land division because the plan does not depict a ‘subdivision’ as defined under the subdivision control law, and requests endorsement of the same. In the case at hand, the proposed land division is not a subdivision so-defined and an ANR endorsement is warranted because the division does not affect the existing, respective frontage of either lot, and the parcel created for conveyance is not itself a building lot. The Board’s endorsement, however, does not itself imply zoning compliance or represent the zoning buildability of the lots; these zoning issues are beyond the scope and authority of the Board under a request for ANR endorsement. The Brewster Zoning Bylaw does expressly allow land area to be added to pre-existing nonconforming lots, similar to what is proposed and depicted on the subject plan. Town Of Brewster 2198 Main Street Brewster, Massachusetts 02631-1898 (508) 896-3701 x1150 Office of: Planning Department MAJOR STORMWATER MANAGEMENT PERMIT, CASE NO. 2023-31 APPLICANT/OWNER: THE LATHAM CENTER, INC. PROPERTY: 1439 MAIN STREET 1 Town of Brewster 2198 Main Street Brewster, MA 02631-1898 Phone: (508) 896-3701 x. 1133 STAFF REPORT TO: Planning Board FROM: Jon Idman, Town Planner RE: Major Stormwater Permit SWMP23-31 1439 Main Street (Map 48 Parcel 61) Applicant: Latham Centers c/o Jeremy Belanger, P.E., TF Moran, Inc. DATE: July 19, 2023 ______________________________________________________________________________ Recommendation The stormwater permit application meets the applicable performance standards and submission requirements set out in the town’s Stormwater Management Regulations for issuance and approval of a Major Stormwater Permit. Approval should be granted subject to the continuing obligations set out in said Regulations, including Sections 5.7, 5.8, 5.9 (Certificates of Compliance), 6.1B (Construction practices), Section 7.2 (Inspections), 8.3 (Recording of stormwater permit and O&M plan) and 8.5 therein. Major Stormwater Management Permit The underlying project is redevelopment of the site for a campus expansion of Latham Centers, including without limitation new parking areas and building additions. Though the project received many of its local permits prior to the effective date of Chapter 272 of the Brewster Code (Stormwater Management Bylaw), given the complex nature of planning and permitting for the redevelopment, the applicant has just now applied for building permits. This is to say, all local permits for the project (including building permits) were not obtained prior to the effective date of said Bylaw. Thus, the project triggers a Major Stormwater Permit according to Section 4 of the Bylaw’s supporting regulations, as the project involves net new impervious surface of 2500 sq ft or greater and greater than 20,000 sq ft total land disturbance. The Planning Board previously granted site plan approval for the redevelopment1, including for proposed stormwater management as an element of site plan review. The current stormwater management approach is substantially similar to that previously reviewed and approved by the Planning Board. The northeastern/ southeastern portion of the property, along the property line, is within the 100’ wetlands buffer. No portion of the project is located in a special flood hazard area. The property is not located in a Zone II or the DCPC. Because the entire stormwater management system and a majority of the project development work is not located within wetlands jurisdiction, it has been agreed that the Planning Board is the stormwater permitting authority after discussion and consultation with the Natural Resources Department. Notwithstanding, Conservation Commission approval is required for any work within the 100’ wetlands 1 The project the Planning Board reviewed has since been reduced in scope based on an appeal of ZBA approval and eventual settlement. Office of: Planning Board Planning Dept. 2 buffer. Major Stormwater Permits are subject to review at a public meeting, including for any waivers requested. No waivers have been requested or identified as necessary. The Applicant has provided the required application materials for a Major Stormwater Permit as set out in Appendix B of the Stormwater Management Regulations, including a site plan set (consisting of 16 sheets, with latest revised date 6/19/23) and Stormwater Management Report, including HydroCad sheets (revised dated 6/26/23). The Applicant has provided construction-period BMPs consistent with the performance standards for Major Stormwater Permits set out in Section 6.1B of the Stormwater Management Regulations. The site plan set contains the specific details of the proposed erosion and sedimentation controls. The post-construction stormwater management system for the project involves catch basins and piping directing run-off to an on-site subsurface leaching facility for infiltration/ recharge. These post-construction BMPs are consistent with the Major Stormwater Permits performance standards for new construction set out in Section 6.2B and Section 8.2 of the Stormwater Management Regulations:  The system meets the applicable standards in the Massachusetts Stormwater Handbook for the combined new development/ redevelopment scenario.  The system will not increase off-site flooding for the 100 yr. storm event, attenuates peak flows for the 25 yr, 24 hr storm event, and reduces peak run-off volumes for the 100 yr. storm.  The system preserves existing recharge volume/ capacity on-site.  The Applicant has provided a corresponding Operations and Maintenance Manual, which adequately addresses the long-term maintenance of the post-construction BMPs.  The Applicant considered Low Impact Development-type (LID) stormwater design elements. Because of site constraints and the circumstances associated with redeveloping a site for institutional use, nature-based facilities could not be incorporated, however, the system reduces the volume of untreated run-off leaving the site, including to nearby wetlands resources. The Applicant has also proposed a landscape plan, including native wetlands buffer species, to reduce proposed impervious areas.  In addition to the MA handbook stormwater standards, the system meets the TSS and Total Phosphorus treatment requirements (TSS) set out in the Regulations for redevelopment, on the basis of pretreatment facilities and the water quality volume/ holding capacity of the subsurface facility. The system treats the ‘first flush’ of run-off.  The Applicant’s soil tests on the property, and NRCS mapping, have revealed well-draining soils.  Test pits suggest that there is sufficient separation from stormwater facilities and the groundwater table. June 21, 2023 TFMoran, Inc. MSC a division of TFMoran, Inc. 48 Constitution Drive, Bedford, NH 03110 170 Commerce Way–Suite 102, Portsmouth, NH 03801 T (603) 472-4488 www.tfmoran.com T (603) 431-2222 July 5, 2023 Amanda Bebrin, Chair Brewster Planning Board 2198 Main Street Brewster, MA 02631-1898 Re: Stormwater Management Permit Application Latham Center 1439 Main Street, Brewster, MA 02631 Tax Map 48, Lot 61 Dear Amanda: On behalf of our client, The Latham Center, Inc., we are pleased to submit the attached Stormwater Management Permit application package for proposed site improvements at the above referenced property. The Latham Center has authorized TFMoran, Inc. to act as their representative for all permitting and siting requirements relating to the proposed project. The project was formerly reviewed and approved in March 2020, in accordance with ZBA Amended Special Permit 21-19, Planning Board Modification of Site Plan Review Approval #2019-28, and DEP Order of Conditions SE9- 1851. Since the time of approval, the proposed redevelopment scope has been decreased, as shown on the revised Plans. As Building Permits were not issued prior to the expiration of former approvals, this Stormwater Management Application reflects a resubmission of the previously granted. The property, zoned Residential Mid Density, is formerly the home of the New England Fire and History Museum and consists of several structures, gravel and paved access and parking areas and open space. Existing access to the site comes via a paved driveway off Main Street (1901 State Highway L.O. 545). Existing topography slopes from the north to the south, with approximately 14 feet of grade change across the property. Abutting uses consist of private residences and an antique store. The redevelopment project proposes removal of two outbuildings, renovation and construction of additions to the existing structures, reconstruction of the existing paved/gravel parking and access areas, improvements to the stormwater management system and upgrades to landscaping features throughout the site. Municipal water and electric service are currently available on the site, septic and drainage improvements will be located on-site. It is anticipated that site costs will be approximately $750,000. The Latham Center is currently operating some administrative offices on the property. In addition to the presented Stormwater Management Permit, the project obtained the aforementioned Town approvals. Should there be any questions or concerns regarding this submittal or the project in general please do not hesitate to contact the undersigned at 603.491.3362 or jbelanger@tfmoran.com. Sincerely, TFMoran, Inc. Jeremy Belanger, PE Senior Project Engineer © © © © © © © © © © ® © WWW.STORMTECH.COM 1-888-892-2694 WWW.STORMTECH.COM 1-888-892-2694 WWW.STORMTECH.COM © © © © The Latham Center Tax Map 48 Lot 61 1439 Main Street Brewster, MA 02631 Prepared On: December 11, 2019 Revised January 30, 2020 Revised June 26, 2023 Prepared for: Latham Centers, Inc. 1646 Main Street Brewster, MA 02631 Job Number: 31848-01 48 Constitution Drive, Bedford, NH 03110 Tel: (603) 472 -4488 Fax : (603) 472 -9747 www.tfmoran.com STORMWATER MANAGEMENT REPORT 31848-01 The Latham Center 1439 Main St, Brewster, MA 02631 The Latham Center 1439 Main Street, Brewster, MA 02631 December 11, 2019 Revised January 30, 2020 Revised June 26, 2023 Table of Contents Part 1 Project Narrative Executive Summary Description of Project Storm Water Methodology Pre-development Conditions Rainfall Intensity Post-development Conditions MassDEP Stormwater Management Standards Standard #1 – No New Untreated Discharges Standard #2 – Peak Rate Attenuation Standard #3 - Recharge Standard #4 – Water Quality Standard #5 – Land Uses with Higher Potential Pollutant Loads (LUHPPL) Standard #6 – Critical Areas Standard #7 – Redevelopment Standards Only to the Maximum Extent Possible Standard #8 – Construction Period Erosion and Sedimentation Controls Standard #9 – Operations and Maintenance Plan Standard #10 – Prohibition of Illicit Discharges Conclusion Part 2 Site Information Site Photographs USGS Map NRCS Web Soil Survey Town of Brewster Tax Map FEMA National Flood Hazard Layer FIRMETTE MA Outstanding Resource Waters Map Natural Heritage and Endangered Species Program (NHESP) Map Extreme Precipitation Table MassDEP Checklist for Stormwater Report Part 3 Calculations Groundwater Recharge Volume (GRV) Water Quality Volume (WQV) Total Suspended Solids (TSS) Removal Percentage Part 4 Pre-development Drainage Analysis Pre-development HydroCAD Calculations Diagram 31848-01 The Latham Center 1439 Main St, Brewster, MA 02631 Area & Soil Listings Node Listing: 2-yr, 10-yr, 25-yr, and 100-yr Full Summary: 2-yr, 10-yr Part 5 Post-Development Drainage Analysis Post-development HydroCAD Calculations Diagram Area & Soil Listings Node Listing: 2-yr, 10-yr, 25-yr, and 100-yr Full Summary: 2-yr, 10-yr Part 6 Test Pit Report Test Pit Report Part 7 Operation and Maintenance Manual Operation and Maintenance Manual Part 8 Drainage Plans Drainage Plan (11x17) Pre-development – Sheet 1 of 2 Post-development – Sheet 2 of 2 Pre-development & Post-development Drainage Plans (Full size in pocket) 31848-01 The Latham Center 1439 Main Street, Brewster, MA 02631 Executive Summary The Latham Center is proposing to redevelop the existing property, located at 1439 Main Street, Tax Map 48 Lot 61 in Brewster, MA. The project proposes to renovate and construct additions to the existing structures, reconstruction of the existing paved/gravel parking and access areas, improvements to the stormwater management system and upgrades to landscaping features throughout the site. The approved stormwater management area was designed under the 2015 Brewster Stormwater Management Regulations, which were subsequently updated in 2022. This Report has been revised to meet the 2022 standards to the greatest extent practical, consistent with the Massachusetts Stormwater Handbook regulations for redevelopment projects. A closed drainage system with subsurface infiltration/recharge is being proposed for the newly developed and redeveloped portions of the site to provide treatment and attenuate stormwater runoff. The system has been designed to maintain peak flows and volumes during the design storm conditions. • Best Management Practices (BMPs) are proposed to manage stormwater runoff on-site and provide treatment, recharge, and maintain existing flow rates leaving the site during the design storm events o The subsurface infiltration/recharge system (prefabricated chambers) will collect and recharge stormwater from the redevelop ed and new development portions of the site. The subsurface system is designed to retain the 25-year storm event, with a flow bypass structure to convey larger storm events around the system. The isolator row will provide pre-treatment by allowing sediment to settle out of the stormwater prior to entering the adjacent StormTech chambers and the stormwater receives treatment as it percolates through the soil allowing for filtration and absorption by the organic matter and mineral complexes. Biological and chemical processes occurring within the soil continue the breakdown of pollutants. Infiltration also provides groundwater recharge. • There will be no increase in the peak rate of runoff or volume during the design storms (2-year, 10-year and 25-yer) at the discharge points from the project site. • The Water Quality Volume (WQV), Groundwater Recharge Volume (GRV) and Total Suspended Solids (TSS) Removal requirements have been met by providing the required storage below the lowest outlet orifice of the subsurface system. 31848-01 The Latham Center 1439 Main Street, Brewster, MA 02631 Description of Project The property, located at 1439 Main Street, is formally the home of the New England Fire and History Museum and consists of several structures, gravel and paved access and parking areas and open space. Existing access to the site comes via a paved driveway off Main Street (Route 6 f/n/a 1901 State Highway L.O. 545). The Latham Center is a leader in the treatment of children and adults with intellectual disabilities, complex special needs including Prader-Willi Syndrome, and behavioral challenges. Founded in 1970, Latham Centers provides residential care, education, and treatment at their main campus, located at 1646 Main Street, in Brewster, MA. The Center has recently purchased the subject parcel and is currently operating a small number of administrative duties within the existing office building. As part of the project as presented, the Center is proposing to expand the current administrative and educational facility, to serve as administrative office space and an educational facility, including gym and auditorium. No residential facilities are proposed on the subject parcel. The redevelopment and new construction propose removal of two outbuildings, renovation, and construction of additions to the existing structures, reconstruction of the existing paved/gravel parking and access areas, improvements to the stormwater management system and upgrades to landscaping features throughout the site. Municipal water, gas, and electric services, currently available on the site, will be extended as part of the proposed design. Septic and drainage improvements will be located on-site. Existing drainage flow paths will be maintained throughout the site in pre- to post- development conditions. One subsurface infiltration/recharge system is proposed for stormwater management. A closed drainage system will convey stormwater runoff to the proposed system. The existing lot is a total of 1.52+/- acres and approximately 1.40+/- acres will be disturbed as part of the proposed redevelopment. Examination of the Flood Insurance Rate Map for Barnstable County (All Jurisdictions), Massachusetts, Map Numbered 25001C0413J, Effective Date: July 16, 2014, indicates that the proposed work is not located within a 100-year flood hazard area. In addition to a Wetland Buffer Impact NOI from the Town of Brewster Conservation Commission, the proposed work will require Town Site Plan Approval (conditionally approved on January 20, 2020), a Special Permit from the Town of Brewster Zoning Board of Appeals (granted on January 14, 2020), and a WPA Form 3 – NOI from the Massachusetts Department of Environmental Protection (Mass DEP) (NOI #009-1851, filed February 11, 2020). The objectives for the post-development drainage design are to use BMPs to attenuate flows, provide improved pre-treatment and treatment to collected stormwater runoff, increase groundwater recharge, and improve current on-site stormwater management 31848-01 The Latham Center 1439 Main Street, Brewster, MA 02631 practices pursuant to the ten (10) standards as outline in the MassDEP Stormwater Policy to the greatest extent possible. The intent of this report is: 1) to analyze the rate of runoff and volume from the site for the pre-and post-development conditions; the drainage system will be designed to maintain the current peak rate of runoff from the site during the design storms, and 2) to provide stormwater treatment and recharge for the runoff from the redevelopment prior to discharging runoff from the site in accordance with the requirements of the MassDEP and the Town of Brewster. 31848-01 The Latham Center 1439 Main Street, Brewster, MA 02631 Storm Water Methodology Pre-Development Conditions Based on the existing topography, six watershed areas and three design/discharge points have been defined. Design Point A represents runoff leaving the northern and eastern property lines towards Lot 48-62, ultimately discharging to the on-site wetland, owned by Kathleen Megan Kelleher. Design Point B represents runoff flowing in the southern direction to two (2) existing leaching catch basins, located within the southern paved parking area. Overflow from the catch basins enters the Main Street Right-of-way (ROW), where it flows in a roadside swale or enters the municipal closed drainage system before ultimately discharging to the Lot 48-62 on-site wetland. Design Point C represents flow runoff in the western direction to Lot 48 -60, owned by Charles & Julie Howe. Curve numbers for subcatchments were calculated based upon existing ground cover and Natural Resources Conservation Service (NRCS) Hydrologic Soil Groups (HSG). The time of concentration (Tc) for the subcatchments were determined using the existing ground cover and topography. The Pre-development Drainage Map has been included in Part 8 of this report. The NRCS Web Soil Survey mapping was referenced for the subject property which resulted in HSG “A” and “C” soils. A copy of the NRCS report can be found in Part 2 o f this report. Test pits and percolation tests were performed as part of the project design. The rates and depth to seasonal high groundwater used in these calculations are based on those values obtained, with a factor of safety. A copy of the Test Pit report has been included in Part 6 of this report. Rainfall Intensity Rainfall data was collected using the “Extreme Precipitation in a Changing Climate for New York and the New England States”, published by The Northeast Regional Climate Center (NRCC) in partnership with Cornell University. The following rainfall intensities were modeled in the drainage analysis and a full table of Rainfall Intensities has been included in Part 2 of this report: 24-hr Extreme Precipitation Estimates 2-year 3.25 inches 10-year 4.73 inches 25-year 5.87 inches 100-year 8.14 inches 31848-01 The Latham Center 1439 Main Street, Brewster, MA 02631 Post-Development Conditions The proposed site will include the building additions at the above noted address with reconstruction of the existing paved/gravel parking and access areas. The proposed additions reside on the northern and western portions of the site, with the parking and access reconstruction along the southern and eastern portions of the site. Stormwater runoff for the majority of the redevelopment will be conveyed through a closed drainage system to the proposed subsurface infiltration/recharge system which will allow for removal of pollutants prior to recharging the aquifer. Low Impact Design (LID) considerations were reviewed as part of the stormwater management design, as required by the Brewster Stormwater Management Regulations. Due to the existing lot size, developed nature of the site, and adjacent wetlands, LID for the project consists of reducing the area of untreated stormwater runoff leaving the site. Additional LIDs were evaluated as part of the design but given the limited area for potential open drainage management areas, were deemed infeasible. By revising the existing drainage flow paths, installing curbing, and closed drainage systems, the post-development conditions will attenuate, convey, and treat approximately 16,000 square feet of area which was previously allowed to leave the site untreated in the pre-development conditions. The objectives for the post-development drainage design are to use best management practices to attenuate the flow, provide pre-treatment and treatment to collected stormwater and increase groundwater recharge. The post-development drainage model represents the site divided into multiple subcatchments based on the layout of the proposed stormwater collection system. The GRV, WQV and TSS Removal requirements have been met via the proposed subsurface infiltration/recharge system. Calculations can be found in Part 3 of this report. Utilizing the United States Environmental Protection Agency (EPA) Region 1’s BMP Accounting and Tracking Tool (2016), the proposed subsurface Infiltration Basin is capable of removing 92.6% Total Phosphorous (TP), and 97.3% Total Nitrogen (TN) from stormwater runoff. All pre-development discharge points have been analyzed in post-development conditions. To model site hydrology, HydroCAD Version 10.00 program has been used. The software is based on the SCS TR-20 technique used for modeling the hydrology and hydraulics of storm water runoff. The 2-year, 10-year, and 25-year storm events were utilized for design of the proposed stormwater management system, and the 100-year storm event was evaluated for downstream impacts in accordance with the requirements of the MassDEP and the Town of Brewster. 31848-01 The Latham Center 1439 Main Street, Brewster, MA 02631 MassDEP Stormwater Management Standards Due to the existing development of the site, the project meets the criteria of a combination of new development and redevelopment. The proposed construction will increase the amount of on-site impervious by approximately 0.17 acres. While there is an increase in impervious surfaces, the existing conditions provide minimal to no pre-treatment or treatment of stormwater runoff prior to discharging from the site The two (2) existing catch basins located in the southern portion of the site provide minimal groundwater recharge, while the majority of the site’s runoff sheet flows in the southern direction before exiting the site. The redevelopment proposes to install a stormwater management system which complies with the applicable MassDEP Stormwater Management Policy Standards. The project has been designed to meet or exceed the Ten (10) Standards described below. Standard #1 – No New Untreated Discharges The proposed design captures the majority of the existing paved and gravel surfaces and all new paved surfaces and attenuates and treats the stormwater runoff in the proposed subsurface infiltration/recharge system. The amount of untreated runoff has decreased by greater than 16,000 square feet in the pre- to post-development conditions. Existing drainage flow paths were maintained for design of the system outlet, and no new discharge points were created. Stormwater quality control for the project includes street sweeping, hooded catch basins, and a subsurface infiltration/recharge system. Standard #2 – Peak Rate Attenuation Stormwater management controls were developed for the 2-year, 10-year, and 25-year, 24-hour storm events. Under the pre-and post-development conditions, hydrologic analyses were performed utilizing the HydroCAD Version 10.00 program. The software is based on the SCS TR-20 technique used for modeling the hydrology and hydraulics of stormwater runoff. Results from this analysis can be found in the summary table below. FLOW (CFS) 2-YR 10-YR 25-YR 100-YR PRE POST PRE POST PRE POST PRE POST A 1.4 0.7 3.1 1.5 4.5 2.2 7.5 7.8* B 1.0 0.7 1.8 1.3 2.6 1.8 4.1 2.9 C 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 *volume discharged in 100-year storm event decreased by 23.5%, therefore no downstream impacts are anticipated As shown in the table, there is a decrease at the identified discharge points in the design storm events and a minimal increase in peak flow during the 100-year storm event at discharge Design Point A, identified as the wetlands located on Lot 48-62. As one of the governing criteria of this Standard is to demonstrate that peak flows will not increase off- site flooding, volume calculations have been presented in the table below. 31848-01 The Latham Center 1439 Main Street, Brewster, MA 02631 Volume (CF) 2-YR 10-YR 25-YR 100-YR PRE POST PRE POST PRE POST PRE POST A 4,840 3,024 10,074 6,190 14,637 9,978 24,523 18,720 B 3,056 2,762 5,937 5,153 8,359 7,156 13,469 11,376 C 0 0 25 13 83 46 273 164 The results demonstrate that there is a net decrease in runoff volumes during all storm events, which indicates that the proposed design will not increase off-site flooding, due to less volume discharging off-site and increased groundwater recharge through the proposed subsurface infiltration/recharge system. To protect the downstream discharge points from erosion at the proposed outlets, riprap aprons have been provided to dissipate concentrated flows. Standard #3 – Recharge The total proposed impervious area over the project site is 0.94 acres. Therefore, the required Groundwater Recharge Volume (GRV) is calculated utilizing the Massachusetts Stormwater Handbook Volume 3, Chapter 1, Equation (1), which states that the Required Recharge Volume (Rv) is equal to the Target Depth Factor associated wi th each NRCS Hydrologic Soil Group (F) multiplied by the Impervious Area on site (Rv=F x Impervious Area). The site consists of HSG A and C soils, which have a target depth factor of 0.6 0- inches and 0.25-inches, respectively. Therefore: Rv = [(0.6-in/12)x(0.91-ac)]+[(0.25-in/12)x(0.04-ac)] = 0.046 ac-ft or 2,018 cf Referring to Massachusetts Stormwater Handbook Volume 3, Chapter 1, Table 2.3.3. 1982 Rawls Rates, the infiltration rate/recharge area of the subsurface system is designed using the infiltration rate of 2.41 inches/hour for HSG A soils. Using the most conservative “static” storage volume method, the recharge areas provide approximately 0.06 acre-feet or 2,661 cubic feet of static stormwater storage volume below the lowest outlet orifice of the subsurface system. The proposed subsurface infiltration system has a surface area of 1,709 square-feet and using an infiltration rate of 2.41 inches/hour, the system as designed will drain in less than 72 hours. Refer to Part 3 of this repor t for calculations. Standard #4 – Water Quality Proposed Best Management Practices (BMPs) will be utilized to provide the required water quality for the site. The following BMPs will be provided on-site: street-sweeping and a subsurface infiltration/recharge system with pre -treatment isolator row. These BMPs will provide for greater than the required 80% TSS removal. Street Sweeping A comprehensive source reduction program of regular pavement sweeping, litter removal, and maintenance of trash areas will be implemented at the site to protect water quality by 31848-01 The Latham Center 1439 Main Street, Brewster, MA 02631 reducing the amount of sediment and pollutants entering the stormwater management system. The sweeping program will remove sand and contaminants directly from paved surfaces prior to mobilization and transportation to the drainage system during rainfall events. Paved areas will be cleaned and maintained at least twice per year, typically following snowmelt (spring) and leaf-drop (fall), as well as additionally throughout the year, as necessary. In accordance with MassDEP standards, a 10% TSS removal rate is achieved by this BMP. Subsurface Infiltration/Recharge System The proposed subsurface infiltration/recharge system will provide pre-treatment, treatment, and groundwater recharge and treatment of stormwater runoff prior to discharge. The system consists of a series of StormTech SC-740 chamber units enclosed within 1 to 2-inch, double-washed, crushed, angular stone and filter fabric. As designed, the system utilizes a water quality Isolator Row, which acts as pre-treatment and is a component of the StormTech proprietary design. The system has been designed to provide attenuation and treatment of the collected stormwater runoff. In accordance with MassDEP standards, an 80% TSS removal rate is achieved by this BMP when combined with a pre-treatment BMP (Isolator Row). These BMPs provide a calculated 87% TSS removal rate, greater than the required 80% removal. Calculations have been included in Part 3 and a Maintenance and Operations Plan has been included in Part 7 of this report. Standard #5 – Land Uses with Higher Potential Pollutant Loads The proposed site redevelopment project does not fall within “land uses with higher potential pollutant loads” (LUHPPL) as defined by 310 CMR 10.04 and is not subject to a National Pollutant Discharge Elimination System (NPDES) permit o r a NPDES Multi- sector General Permit (MSGP). Standard #6 – Critical Areas Critical Areas are defined as Outstanding Resource Waters (ORWs), recharged areas for public water supplies, bathing beaches, cold-water fisheries and shellfish growing areas. No critical areas as defined are located within or adjacent to the project. See Part 2 of this report for ORW exhibit. Standard #7 – Redevelopment Standards Only to the Maximum Extent Practicable As the proposed project is a combination of new development and redevelopment of the existing site, by regulation the proposed design must meet the MassDEP Stormwater Management Standards to the maximum extent possible taking into consideration cost, land area requirements, soils, and other site constraints. The existing site consists of approximately 0.78 acres of impervious surface (roofs, pavement and gravel parking and access areas, sidewalks, etc.), the majority of which sheet flows from the site in th e southeast direction prior to discharging to the wetlands located on Lot 48-62. Runoff from portions of the southern paved parking area enter two (2) existing on -site leaching catch basins, overtopping during larger storm events into the Main Street (Route 6A) ROW and closed drainage system, ultimately discharging into the wetlands located on Lot 48 -62. 31848-01 The Latham Center 1439 Main Street, Brewster, MA 02631 The proposed stormwater management system decreases the amount of untreated impervious runoff leaving the site by greater than 16,000 square -feet (0.37 acres) while decreasing the volume entering the Main Street ROW by an average of 13% during the evaluated storm events. Attempting to capture and treat all stormwater runoff within the redeveloped portions of the site presents an economic hardship, as the required system would be substantially larger in size. Review of the Massachusetts Stormwater Handbook Volume 3, Chapter 3, Redevelopment Checklist, determines that the proposed design has achieved the following to the maximum extent possible: • Existing discharge points have been brought into compliance by collecting stormwater runoff which previously left the site untreated and convey it to the proposed subsurface infiltration/recharge system providing pre-treatment, treatment, and groundwater recharge, • Attenuates peak flow rates for the design storms and reduces total volume leaving the site during all evaluated storm events, • Increases the volume of recharge to groundwater by storing greater than the required GRV within the proposed infiltration system, where runoff previously flowed across impervious surfaces off-site, and • Achieves greater than the required 80% TSS removal through the proposed BMPs, where currently none exist. The proposed design meets the redevelopment requirements to improve existing conditions to the greatest extent possible and meets the criteria of this Standard. Standard #8 – Construction Period Erosion and Sedimentation Control Erosion and Sediment control BMPs will be employed during construction and earth disturbing phases of the proposed project. These include installation and maintenance of a stabilized construction entrance, silt sock or silt fencing, and catch basin protection. The contractor will be responsible for implementing and maintaining these BMPs as shown on the Wetland Buffer Impact Plan. The erosion control notes and construction sequence notes on the Detail Sheets contain specifications for stabilizing disturbed areas and limiting the length of time these areas are exposed. These plans can be found within the Wetland Buffer Impact Plans, submitted in conjunction with this report. Standard #9 – Operations and Maintenance Plan An Operations and Maintenance Plan for the project has been prepared i n accordance with MassDEP Stormwater Management Standard No. 9 , found in Part 7 of this report. Maintenance of the stormwater management system will be the responsibility of the Owner, Latham Centers, Inc. The owner may retain a Project Manager who will be responsible for the system during construction. At completion, the Owner will be responsible for the long-term operations and maintenance. Standard #10 – Prohibition of Illicit Discharges Illicit discharges to the on-site stormwater management system are prohibited. The project does not include any new off-site drainage connections to the existing municipal system within the Main Street (Route 6) ROW. No illicit connections to the local drainage system or discharges to or from the on-site system will be made. 31848-01 The Latham Center 1439 Main Street, Brewster, MA 02631 Conclusion The proposed stormwater management system addresses both the quantity control and quality of stormwater runoff from the site and meets or exceeds the requirements of the ten (10) Standards as outlined by the MassDEP Stormwater Policy. Latham Center 1439 Main Street Brewster, MA Latham Center – Site Photographs Photo 1 Existing paved driveway and parking area via Google Street View, looking north from Main Street Photo 2 Aerial Imagery of the existing facility (Tax Map 48, Lot 61) and proposed area of work (in red) Latham Center 1439 Main Street Brewster, MA Photo 3 Existing paved parking area, looking south towards Main Street Photo 4 Existing structure located in northern portion of property, looking south from northern property line Latham Center 1439 Main Street Brewster, MA Photo 5 Existing stockade fencing along western property line, looking south towards Main Street Photo 6 Existing structure located in southern portion of property, looking south towards Main Street Latham Center 1439 Main Street Brewster, MA Photo 7 Existing grass courtyard, looking south towards Main Street Photo 8 Existing gravel access area located along eastern portion of property Soil Map—Barnstable County, Massachusetts (1439 MAIN STREET BREWSTER MA) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/3/2019 Page 1 of 3 462 2 8 3 0 462 2 8 6 0 462 2 8 9 0 462 2 9 2 0 462 2 9 5 0 462 2 9 8 0 462 3 0 1 0 462 3 0 4 0 462 3 0 7 0 462 2 8 3 0 462 2 8 6 0 462 2 8 9 0 462 2 9 2 0 462 2 9 5 0 462 2 9 8 0 462 3 0 1 0 462 3 0 4 0 462 3 0 7 0 408670 408700 408730 408760 408790 408820 408850 408670 408700 408730 408760 408790 408820 41° 45' 15'' N 70 ° 5 ' 5 4 ' ' W 41° 45' 15'' N 70 ° 5 ' 4 6 ' ' W 41° 45' 7'' N 70° 5 ' 5 4 ' ' W 41° 45' 7'' N 70° 5 ' 4 6 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 19N WGS84 0 50 100 200 300 Feet 0 15 30 60 90 Meters Map Scale: 1:1,190 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:25,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Barnstable County, Massachusetts Survey Area Data: Version 16, Sep 12, 2019 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 10, 2018—Nov 17, 2018 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. Soil Map—Barnstable County, Massachusetts (1439 MAIN STREET BREWSTER MA) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/3/2019 Page 2 of 3 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 55A Freetown coarse sand, 0 to 3 percent slopes, sanded surface 0.4 6.2% 225B Belgrade silt loam, 3 to 8 percent slopes 1.6 27.1% 435C Plymouth loamy coarse sand, 8 to 15 percent slopes 3.9 64.9% 494C Barnstable-Plymouth- Nantucket complex, rolling, very bouldery 0.1 1.7% Totals for Area of Interest 5.9 100.0% Soil Map—Barnstable County, Massachusetts 1439 MAIN STREET BREWSTER MA Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/3/2019 Page 3 of 3 11/1/2019 ArcGIS - My Map https://www.arcgis.com/home/webmap/print.html 1/1 Esri Community Maps Contributors, MassGIS, BuildingFootprintUSA, Esri, HERE, Garmin, INCREMENT P, METI/NASA, USGS, EPA, NPS, US Census Bureau, USDA My Map ORW - Outstanding Resource Waters Public Water Supply Contributor Other ORW 200ft 10/21/2019 Extreme Precipitation Tables: 41.753°N, 70.097°W precip.eas.cornell.edu/data.php?1571671342077 1/1 Extreme Precipitation Tables Northeast Regional Climate Center Data represents point estimates calculated from partial duration series. All precipitation amounts are displayed in inches. Smoothing Yes State Massachusetts Location Longitude 70.097 degrees West Latitude 41.753 degrees North Elevation 0 feet Date/Time Mon, 21 Oct 2019 11:24:58 -0400 Extreme Precipitation Estimates 5min 10min 15min 30min 60min 120min 1hr 2hr 3hr 6hr 12hr 24hr 48hr 1day 2day 4day 7day 10day 1yr 0.29 0.45 0.55 0.72 0.91 1.14 1yr 0.78 1.13 1.33 1.68 2.14 2.73 3.13 1yr 2.42 3.01 3.45 4.07 4.68 1yr 2yr 0.36 0.56 0.70 0.92 1.16 1.45 2yr 1.00 1.38 1.68 2.09 2.61 3.25 3.65 2yr 2.87 3.51 3.97 4.72 5.30 2yr 5yr 0.44 0.69 0.86 1.15 1.47 1.86 5yr 1.27 1.77 2.15 2.66 3.28 4.02 4.51 5yr 3.56 4.34 4.90 5.72 6.41 5yr 10yr 0.51 0.80 1.01 1.37 1.77 2.25 10yr 1.53 2.14 2.60 3.21 3.91 4.73 5.31 10yr 4.19 5.10 5.75 6.60 7.41 10yr 25yr 0.61 0.97 1.23 1.70 2.26 2.89 25yr 1.95 2.74 3.34 4.09 4.93 5.87 6.58 25yr 5.19 6.33 7.11 7.99 8.98 25yr 50yr 0.70 1.13 1.45 2.03 2.73 3.49 50yr 2.35 3.31 4.03 4.91 5.86 6.91 7.75 50yr 6.11 7.45 8.35 9.24 10.39 50yr 100yr 0.82 1.32 1.70 2.41 3.28 4.21 100yr 2.83 4.00 4.85 5.88 6.97 8.14 9.13 100yr 7.20 8.78 9.82 10.70 12.03 100yr 200yr 0.95 1.54 2.00 2.87 3.95 5.08 200yr 3.41 4.84 5.85 7.05 8.30 9.59 10.77 200yr 8.49 10.36 11.55 12.41 13.93 200yr 500yr 1.16 1.91 2.49 3.61 5.06 6.51 500yr 4.36 6.23 7.49 8.96 10.43 11.92 13.41 500yr 10.55 12.90 14.32 15.12 16.93 500yr Lower Confidence Limits 5min 10min 15min 30min 60min 120min 1hr 2hr 3hr 6hr 12hr 24hr 48hr 1day 2day 4day 7day 10day 1yr 0.25 0.38 0.47 0.63 0.77 0.92 1yr 0.67 0.90 1.09 1.59 1.98 2.34 2.57 1yr 2.07 2.48 3.17 3.53 4.30 1yr 2yr 0.35 0.54 0.66 0.90 1.11 1.36 2yr 0.95 1.33 1.56 2.09 2.64 3.17 3.56 2yr 2.80 3.42 3.85 4.64 5.18 2yr 5yr 0.41 0.63 0.78 1.07 1.36 1.65 5yr 1.17 1.62 1.94 2.54 3.10 3.76 4.25 5yr 3.32 4.09 4.61 5.43 6.09 5yr 10yr 0.46 0.70 0.87 1.21 1.57 1.92 10yr 1.35 1.88 2.24 2.87 3.49 4.26 4.81 10yr 3.77 4.62 5.16 6.06 6.83 10yr 25yr 0.53 0.81 1.01 1.44 1.89 2.33 25yr 1.63 2.28 2.62 3.31 4.10 5.07 5.71 25yr 4.49 5.49 6.12 6.90 7.93 25yr 50yr 0.60 0.91 1.13 1.62 2.18 2.70 50yr 1.88 2.64 2.93 3.66 4.64 5.79 6.52 50yr 5.12 6.27 6.95 7.65 8.89 50yr 100yr 0.68 1.02 1.28 1.85 2.53 3.13 100yr 2.19 3.06 3.32 4.05 5.27 6.64 7.47 100yr 5.87 7.18 7.90 8.43 9.95 100yr 200yr 0.76 1.14 1.45 2.10 2.93 3.65 200yr 2.53 3.57 3.74 4.43 5.98 7.60 8.58 200yr 6.72 8.25 9.03 9.32 11.18 200yr 500yr 0.90 1.33 1.71 2.49 3.54 4.51 500yr 3.06 4.41 4.40 5.00 7.09 9.13 10.38 500yr 8.08 9.98 10.82 10.65 13.08 500yr Upper Confidence Limits 5min 10min 15min 30min 60min 120min 1hr 2hr 3hr 6hr 12hr 24hr 48hr 1day 2day 4day 7day 10day 1yr 0.34 0.52 0.64 0.86 1.05 1.29 1yr 0.91 1.26 1.53 2.06 2.57 3.02 3.37 1yr 2.67 3.24 3.73 4.37 4.99 1yr 2yr 0.38 0.59 0.73 0.99 1.22 1.49 2yr 1.05 1.45 1.70 2.35 2.83 3.36 3.80 2yr 2.98 3.66 4.14 4.88 5.54 2yr 5yr 0.49 0.75 0.93 1.27 1.62 1.96 5yr 1.40 1.91 2.27 2.95 3.67 4.31 4.77 5yr 3.81 4.59 5.18 5.98 6.72 5yr 10yr 0.59 0.91 1.13 1.58 2.04 2.43 10yr 1.76 2.38 2.80 3.55 4.45 5.19 5.78 10yr 4.59 5.55 6.28 7.03 7.91 10yr 25yr 0.78 1.18 1.47 2.10 2.76 3.25 25yr 2.38 3.18 3.87 4.68 5.74 6.66 7.38 25yr 5.90 7.10 8.01 9.05 9.82 25yr 50yr 0.95 1.44 1.79 2.58 3.47 4.04 50yr 3.00 3.95 4.87 5.74 6.96 8.04 8.87 50yr 7.11 8.53 9.63 10.81 11.56 50yr 100yr 1.16 1.76 2.20 3.18 4.36 5.03 100yr 3.77 4.92 6.12 7.05 8.45 9.69 10.66 100yr 8.58 10.25 11.56 12.91 13.62 100yr 200yr 1.43 2.15 2.73 3.95 5.51 6.25 200yr 4.75 6.11 7.71 8.69 10.24 11.68 12.79 200yr 10.34 12.29 13.89 15.48 16.04 200yr 500yr 1.89 2.81 3.61 5.25 7.46 8.30 500yr 6.44 8.11 10.47 11.49 13.21 14.96 16.28 500yr 13.24 15.66 17.68 19.72 19.91 500yr 31848-01 swcheck_2020-01-30.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 A. Introduction Important: When filling out forms on the computer, use only the tab key to move your cursor - do not use the return key. 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.1 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 Sedimentat ion Control Plan before commencing any land disturbance activity on the site. 31848-01 swcheck_2020-01-30.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) 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. 31848-01 swcheck_2020-01-30.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 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 Field1 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. 31848-01 swcheck_2020-01-30.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 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. 31848-01 swcheck_2020-01-30.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 4: Water Quality (continued) The BMP is sized (and calculations provided) based on: The ½” 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. 31848-01 swcheck_2020-01-30.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 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. 31848-01 swcheck_2020-01-30.doc • 04/01/08 Stormwater Report Checklist • Page 8 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 R eport 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. 31848-01 swcheck_2020-01-30.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 A. Introduction Important: When filling out forms on the computer, use only the tab key to move your cursor - do not use the return key. 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.1 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 Sedimentat ion Control Plan before commencing any land disturbance activity on the site. HSG Area replaced by impervious (ac) Target Depth Factor (in) Required Recharge Volume (CF) Provided Volume (CF) A 0.91 0.6 1,982 - B 0 0.35 - 0 C 0.04 0.25 36 0 D 0 0.1 - 0 Total 2,018 2,661 Latham Center 1439 Main Street, Brewster, MA December 11, 2019 Recharge Volume Calculation Stormtech System A (Imp) (acres) D(wq) (inches) V(wq) (cf) Provided Volume (CF) 0.51 1.0 1,851 2,661 Latham Center 1439 Main Street, Brewster, MA Water Quality Volume Calculation December 11, 2019 Stormtech System Type III 24-hr 25-YR Rainfall=5.87"31848-01 Post-Development_2019-12-11 Printed 12/11/2019Prepared by Microsoft HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Stage-Area-Storage for Pond 1P: ST.TECH-740 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 39.00 1,709 0 39.05 1,709 34 39.10 1,709 68 39.15 1,709 103 39.20 1,709 137 39.25 1,709 171 39.30 1,709 205 39.35 1,709 239 39.40 1,709 273 39.45 1,709 308 39.50 1,709 342 39.55 1,709 412 39.60 1,709 482 39.65 1,709 551 39.70 1,709 621 39.75 1,709 690 39.80 1,709 760 39.85 1,709 829 39.90 1,709 897 39.95 1,709 966 40.00 1,709 1,034 40.05 1,709 1,102 40.10 1,709 1,169 40.15 1,709 1,237 40.20 1,709 1,304 40.25 1,709 1,370 40.30 1,709 1,436 40.35 1,709 1,502 40.40 1,709 1,568 40.45 1,709 1,633 40.50 1,709 1,698 40.55 1,709 1,762 40.60 1,709 1,826 40.65 1,709 1,889 40.70 1,709 1,952 40.75 1,709 2,015 40.80 1,709 2,077 40.85 1,709 2,138 40.90 1,709 2,199 40.95 1,709 2,259 41.00 1,709 2,319 41.05 1,709 2,378 41.10 1,709 2,436 41.15 1,709 2,494 41.20 1,709 2,550 41.25 1,709 2,606 41.30 1,709 2,661 41.35 1,709 2,715 41.40 1,709 2,769 41.45 1,709 2,821 41.50 1,709 2,872 41.55 1,709 2,922 41.60 1,709 2,971 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 41.65 1,709 3,018 41.70 1,709 3,063 41.75 1,709 3,106 41.80 1,709 3,146 41.85 1,709 3,184 41.90 1,709 3,221 41.95 1,709 3,257 42.00 1,709 3,292 42.05 1,709 3,326 42.10 1,709 3,360 42.15 1,709 3,394 42.20 1,709 3,428 42.25 1,709 3,463 42.30 1,709 3,497 42.35 1,709 3,531 42.40 1,709 3,565 42.45 1,709 3,599 42.50 1,709 3,633 42.55 1,709 3,633 42.60 1,709 3,633 42.65 1,709 3,633 42.70 1,709 3,633 42.75 1,709 3,633 42.80 1,709 3,633 42.85 1,709 3,633 42.90 1,709 3,633 42.95 1,709 3,633 43.00 1,709 3,633 43.05 1,709 3,633 43.10 1,709 3,633 43.15 1,709 3,633 43.20 1,709 3,633 43.25 1,709 3,633 43.30 1,709 3,633 43.35 1,709 3,633 43.40 1,709 3,633 43.45 1,709 3,633 43.50 1,709 3,633 V INSTRUCTIONS:Version 1, Automated: Mar. 4, 2008 1. In BMP Column, click on Blue Cell to Activate Drop Down Menu 2. Select BMP from Drop Down Menu 3. After BMP is selected, TSS Removal and other Columns are automatically completed. Location: B C D E F TSS Removal Starting TSS Amount Remaining BMP1 Rate1 Load*Removed (C*D)Load (D-E) Street Sweeping - 10%0.10 1.00 0.10 0.90 Subsurface Infiltration Structure 0.80 0.90 0.72 0.18 0.00 0.18 0.00 0.18 0.00 0.18 0.00 0.18 0.00 0.18 0.00 0.18 Total TSS Removal =82% Separate Form Needs to be Completed for Each Outlet or BMP Train Project:Latham Center Prepared By:J.Belanger *Equals remaining load from previous BMP (E) Date:12/10/2019 which enters the BMP TS S R e m o v a l Ca l c u l a t i o n W o r k s h e e t Stormtech System Non-automated TSS Calculation Sheet must be used if Proprietary BMP Proposed 1. From MassDEP Stormwater Handbook Vol. 1 Mass. Dept. of Environmental Protection 1S SUBCAT 1 2S SUBCAT 2 3S SUBCAT 3 4S SUBCAT 4 5S SUBCAT 5 6S SUBCAT 6 1R EX. DRAINAGE 7P EX. CB A LOT 48-62 B MAIN ST ROW C LOT 48-60 Routing Diagram for 31848-01 Pre-Development_2020-01-30 Prepared by Microsoft, Printed 1/29/2020 HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Subcat Reach Pond Link 31848-01 Pre-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 2HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (sq-ft) CN Description (subcatchment-numbers) 26,463 39 >75% Grass cover, Good, HSG A (1S, 2S, 3S, 4S, 5S, 6S) 1,088 74 >75% Grass cover, Good, HSG C (1S) 6,942 96 Gravel surface, HSG A (1S, 4S) 1,709 96 Gravel surface, HSG C (1S) 15,976 98 Paved parking, HSG A (2S, 3S, 4S) 9,097 98 Roofs, HSG A (1S, 4S) 196 98 Roofs, HSG C (1S) 3,957 30 Woods, Good, HSG A (1S, 6S) 694 70 Woods, Good, HSG C (1S) 66,122 69 TOTAL AREA 31848-01 Pre-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 3HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Soil Listing (all nodes) Area (sq-ft) Soil Group Subcatchment Numbers 62,435 HSG A 1S, 2S, 3S, 4S, 5S, 6S 0 HSG B 3,687 HSG C 1S 0 HSG D 0 Other 66,122 TOTAL AREA Type III 24-hr 2-YR Rainfall=3.25"31848-01 Pre-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 4HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=31,968 sf 21.75% Impervious Runoff Depth>0.67"Subcatchment 1S: SUBCAT 1 Flow Length=196' Tc=6.5 min CN=66 Runoff=0.5 cfs 1,778 cf Runoff Area=366 sf 27.87% Impervious Runoff Depth>0.27"Subcatchment 2S: SUBCAT 2 Tc=6.0 min CN=55 Runoff=0.0 cfs 8 cf Runoff Area=410 sf 40.00% Impervious Runoff Depth>0.54"Subcatchment 3S: SUBCAT 3 Tc=6.0 min CN=63 Runoff=0.0 cfs 18 cf Runoff Area=29,097 sf 62.03% Impervious Runoff Depth>1.31"Subcatchment 4S: SUBCAT 4 Flow Length=276' Tc=7.2 min CN=78 Runoff=1.0 cfs 3,172 cf Runoff Area=1,092 sf 0.00% Impervious Runoff Depth>0.00"Subcatchment 5S: SUBCAT 5 Tc=6.0 min CN=39 Runoff=0.0 cfs 0 cf Runoff Area=3,189 sf 0.00% Impervious Runoff Depth=0.00"Subcatchment 6S: SUBCAT 6 Tc=6.0 min CN=37 Runoff=0.0 cfs 0 cf Avg. Flow Depth=0.21' Max Vel=2.4 fps Inflow=1.0 cfs 3,056 cfReach 1R: EX. DRAINAGE n=0.050 L=124.0' S=0.1298 '/' Capacity=60.5 cfs Outflow=0.9 cfs 3,054 cf Peak Elev=42.07' Storage=105 cf Inflow=1.0 cfs 3,172 cfPond 7P: EX. CB Discarded=0.0 cfs 31 cf Primary=1.0 cfs 3,038 cf Outflow=1.0 cfs 3,068 cf Inflow=1.4 cfs 4,840 cfLink A: LOT 48-62 Primary=1.4 cfs 4,840 cf Inflow=1.0 cfs 3,056 cfLink B: MAIN ST ROW Primary=1.0 cfs 3,056 cf Inflow=0.0 cfs 0 cfLink C: LOT 48-60 Primary=0.0 cfs 0 cf Total Runoff Area = 66,122 sf Runoff Volume = 4,977 cf Average Runoff Depth = 0.90" 61.78% Pervious = 40,853 sf 38.22% Impervious = 25,269 sf Type III 24-hr 10-YR Rainfall=4.73"31848-01 Pre-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 5HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=31,968 sf 21.75% Impervious Runoff Depth>1.54"Subcatchment 1S: SUBCAT 1 Flow Length=196' Tc=6.5 min CN=66 Runoff=1.2 cfs 4,114 cf Runoff Area=366 sf 27.87% Impervious Runoff Depth>0.85"Subcatchment 2S: SUBCAT 2 Tc=6.0 min CN=55 Runoff=0.0 cfs 26 cf Runoff Area=410 sf 40.00% Impervious Runoff Depth>1.34"Subcatchment 3S: SUBCAT 3 Tc=6.0 min CN=63 Runoff=0.0 cfs 46 cf Runoff Area=29,097 sf 62.03% Impervious Runoff Depth>2.48"Subcatchment 4S: SUBCAT 4 Flow Length=276' Tc=7.2 min CN=78 Runoff=1.8 cfs 6,016 cf Runoff Area=1,092 sf 0.00% Impervious Runoff Depth>0.15"Subcatchment 5S: SUBCAT 5 Tc=6.0 min CN=39 Runoff=0.0 cfs 13 cf Runoff Area=3,189 sf 0.00% Impervious Runoff Depth>0.10"Subcatchment 6S: SUBCAT 6 Tc=6.0 min CN=37 Runoff=0.0 cfs 25 cf Avg. Flow Depth=0.27' Max Vel=2.8 fps Inflow=1.8 cfs 5,937 cfReach 1R: EX. DRAINAGE n=0.050 L=124.0' S=0.1298 '/' Capacity=60.5 cfs Outflow=1.8 cfs 5,934 cf Peak Elev=42.11' Storage=105 cf Inflow=1.8 cfs 6,016 cfPond 7P: EX. CB Discarded=0.0 cfs 34 cf Primary=1.8 cfs 5,878 cf Outflow=1.8 cfs 5,912 cf Inflow=3.1 cfs 10,074 cfLink A: LOT 48-62 Primary=3.1 cfs 10,074 cf Inflow=1.8 cfs 5,937 cfLink B: MAIN ST ROW Primary=1.8 cfs 5,937 cf Inflow=0.0 cfs 25 cfLink C: LOT 48-60 Primary=0.0 cfs 25 cf Total Runoff Area = 66,122 sf Runoff Volume = 10,241 cf Average Runoff Depth = 1.86" 61.78% Pervious = 40,853 sf 38.22% Impervious = 25,269 sf Type III 24-hr 25-YR Rainfall=5.87"31848-01 Pre-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 6HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=31,968 sf 21.75% Impervious Runoff Depth>2.34"Subcatchment 1S: SUBCAT 1 Flow Length=196' Tc=6.5 min CN=66 Runoff=1.9 cfs 6,238 cf Runoff Area=366 sf 27.87% Impervious Runoff Depth>1.44"Subcatchment 2S: SUBCAT 2 Tc=6.0 min CN=55 Runoff=0.0 cfs 44 cf Runoff Area=410 sf 40.00% Impervious Runoff Depth>2.08"Subcatchment 3S: SUBCAT 3 Tc=6.0 min CN=63 Runoff=0.0 cfs 71 cf Runoff Area=29,097 sf 62.03% Impervious Runoff Depth>3.46"Subcatchment 4S: SUBCAT 4 Flow Length=276' Tc=7.2 min CN=78 Runoff=2.6 cfs 8,391 cf Runoff Area=1,092 sf 0.00% Impervious Runoff Depth>0.41"Subcatchment 5S: SUBCAT 5 Tc=6.0 min CN=39 Runoff=0.0 cfs 37 cf Runoff Area=3,189 sf 0.00% Impervious Runoff Depth>0.31"Subcatchment 6S: SUBCAT 6 Tc=6.0 min CN=37 Runoff=0.0 cfs 83 cf Avg. Flow Depth=0.31' Max Vel=3.0 fps Inflow=2.6 cfs 8,359 cfReach 1R: EX. DRAINAGE n=0.050 L=124.0' S=0.1298 '/' Capacity=60.5 cfs Outflow=2.6 cfs 8,355 cf Peak Elev=42.13' Storage=105 cf Inflow=2.6 cfs 8,391 cfPond 7P: EX. CB Discarded=0.0 cfs 36 cf Primary=2.6 cfs 8,251 cf Outflow=2.6 cfs 8,287 cf Inflow=4.5 cfs 14,637 cfLink A: LOT 48-62 Primary=4.5 cfs 14,637 cf Inflow=2.6 cfs 8,359 cfLink B: MAIN ST ROW Primary=2.6 cfs 8,359 cf Inflow=0.0 cfs 83 cfLink C: LOT 48-60 Primary=0.0 cfs 83 cf Total Runoff Area = 66,122 sf Runoff Volume = 14,864 cf Average Runoff Depth = 2.70" 61.78% Pervious = 40,853 sf 38.22% Impervious = 25,269 sf Type III 24-hr 100-YR Rainfall=8.14"31848-01 Pre-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 7HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=31,968 sf 21.75% Impervious Runoff Depth>4.12"Subcatchment 1S: SUBCAT 1 Flow Length=196' Tc=6.5 min CN=66 Runoff=3.4 cfs 10,971 cf Runoff Area=366 sf 27.87% Impervious Runoff Depth>2.88"Subcatchment 2S: SUBCAT 2 Tc=6.0 min CN=55 Runoff=0.0 cfs 88 cf Runoff Area=410 sf 40.00% Impervious Runoff Depth>3.78"Subcatchment 3S: SUBCAT 3 Tc=6.0 min CN=63 Runoff=0.0 cfs 129 cf Runoff Area=29,097 sf 62.03% Impervious Runoff Depth>5.52"Subcatchment 4S: SUBCAT 4 Flow Length=276' Tc=7.2 min CN=78 Runoff=4.1 cfs 13,373 cf Runoff Area=1,092 sf 0.00% Impervious Runoff Depth>1.21"Subcatchment 5S: SUBCAT 5 Tc=6.0 min CN=39 Runoff=0.0 cfs 110 cf Runoff Area=3,189 sf 0.00% Impervious Runoff Depth>1.03"Subcatchment 6S: SUBCAT 6 Tc=6.0 min CN=37 Runoff=0.0 cfs 273 cf Avg. Flow Depth=0.36' Max Vel=3.4 fps Inflow=4.1 cfs 13,469 cfReach 1R: EX. DRAINAGE n=0.050 L=124.0' S=0.1298 '/' Capacity=60.5 cfs Outflow=4.1 cfs 13,464 cf Peak Elev=42.18' Storage=105 cf Inflow=4.1 cfs 13,373 cfPond 7P: EX. CB Discarded=0.0 cfs 39 cf Primary=4.1 cfs 13,229 cf Outflow=4.1 cfs 13,268 cf Inflow=7.5 cfs 24,523 cfLink A: LOT 48-62 Primary=7.5 cfs 24,523 cf Inflow=4.1 cfs 13,469 cfLink B: MAIN ST ROW Primary=4.1 cfs 13,469 cf Inflow=0.0 cfs 273 cfLink C: LOT 48-60 Primary=0.0 cfs 273 cf Total Runoff Area = 66,122 sf Runoff Volume = 24,944 cf Average Runoff Depth = 4.53" 61.78% Pervious = 40,853 sf 38.22% Impervious = 25,269 sf Type III 24-hr 2-YR Rainfall=3.25"31848-01 Pre-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 1HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: SUBCAT 1 Runoff = 0.5 cfs @ 12.12 hrs, Volume= 1,778 cf, Depth> 0.67" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 6,758 98 Roofs, HSG A 12,670 39 >75% Grass cover, Good, HSG A 5,730 96 Gravel surface, HSG A 3,123 30 Woods, Good, HSG A 196 98 Roofs, HSG C 1,088 74 >75% Grass cover, Good, HSG C 694 70 Woods, Good, HSG C 1,709 96 Gravel surface, HSG C 31,968 66 Weighted Average 25,014 78.25% Pervious Area 6,954 21.75% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.9 97 0.0900 0.3 Sheet Flow, 1a Grass: Short n= 0.150 P2= 2.54" 0.6 99 0.0300 2.8 Shallow Concentrated Flow, 1b Unpaved Kv= 16.1 fps 6.5 196 Total Summary for Subcatchment 2S: SUBCAT 2 Runoff = 0.0 cfs @ 12.32 hrs, Volume= 8 cf, Depth> 0.27" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 102 98 Paved parking, HSG A 264 39 >75% Grass cover, Good, HSG A 366 55 Weighted Average 264 72.13% Pervious Area 102 27.87% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 3S: SUBCAT 3 Runoff = 0.0 cfs @ 12.12 hrs, Volume= 18 cf, Depth> 0.54" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 164 98 Paved parking, HSG A 246 39 >75% Grass cover, Good, HSG A 410 63 Weighted Average 246 60.00% Pervious Area 164 40.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 4S: SUBCAT 4 Runoff = 1.0 cfs @ 12.11 hrs, Volume= 3,172 cf, Depth> 1.31" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 15,710 98 Paved parking, HSG A 2,339 98 Roofs, HSG A 9,836 39 >75% Grass cover, Good, HSG A 1,212 96 Gravel surface, HSG A 29,097 78 Weighted Average 11,048 37.97% Pervious Area 18,049 62.03% Impervious Area Type III 24-hr 2-YR Rainfall=3.25"31848-01 Pre-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 2HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.4 71 0.0600 0.2 Sheet Flow, 4a Grass: Short n= 0.150 P2= 2.54" 0.4 79 0.0500 3.6 Shallow Concentrated Flow, 4b Unpaved Kv= 16.1 fps 1.1 47 0.0100 0.7 Shallow Concentrated Flow, 4c Short Grass Pasture Kv= 7.0 fps 0.0 9 0.2700 3.6 Shallow Concentrated Flow, 4d Short Grass Pasture Kv= 7.0 fps 0.3 70 0.0300 3.5 Shallow Concentrated Flow, 4e Paved Kv= 20.3 fps 7.2 276 Total Summary for Subcatchment 5S: SUBCAT 5 [73] Warning: Peak may fall outside time span Runoff = 0.0 cfs @ 24.00 hrs, Volume= 0 cf, Depth> 0.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 1,092 39 >75% Grass cover, Good, HSG A 1,092 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 6S: SUBCAT 6 [45] Hint: Runoff=Zero Runoff = 0.0 cfs @ 0.00 hrs, Volume= 0 cf, Depth= 0.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 2,355 39 >75% Grass cover, Good, HSG A 834 30 Woods, Good, HSG A 3,189 37 Weighted Average 3,189 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Reach 1R: EX. DRAINAGE Inflow Area = 30,599 sf, 59.52% Impervious, Inflow Depth > 1.20" for 2-YR event Inflow = 1.0 cfs @ 12.11 hrs, Volume= 3,056 cf Outflow = 0.9 cfs @ 12.12 hrs, Volume= 3,054 cf, Atten= 3%, Lag= 0.9 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.4 fps, Min. Travel Time= 0.9 min Avg. Velocity = 1.1 fps, Avg. Travel Time= 1.9 min Peak Storage= 49 cf @ 12.12 hrs Average Depth at Peak Storage= 0.21' Bank-Full Depth= 1.00' Flow Area= 9.0 sf, Capacity= 60.5 cfs 0.00' x 1.00' deep channel, n= 0.050 Scattered brush, heavy weeds Side Slope Z-value= 9.0 '/' Top Width= 18.00' Length= 124.0' Slope= 0.1298 '/' Inlet Invert= 40.00', Outlet Invert= 23.90' ‡ Summary for Pond 7P: EX. CB [87] Warning: Oscillations may require smaller dt or Finer Routing (severity=27) Inflow Area = 29,097 sf, 62.03% Impervious, Inflow Depth > 1.31" for 2-YR event Inflow = 1.0 cfs @ 12.11 hrs, Volume= 3,172 cf Outflow = 1.0 cfs @ 12.11 hrs, Volume= 3,068 cf, Atten= 0%, Lag= 0.0 min Discarded = 0.0 cfs @ 10.10 hrs, Volume= 31 cf Primary = 1.0 cfs @ 12.11 hrs, Volume= 3,038 cf Type III 24-hr 2-YR Rainfall=3.25"31848-01 Pre-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 3HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 42.07' @ 12.11 hrs Surf.Area= 13 sf Storage= 105 cf Plug-Flow detention time= 24.2 min calculated for 3,062 cf (97% of inflow) Center-of-Mass det. time= 6.3 min ( 854.9 - 848.6 ) Volume Invert Avail.Storage Storage Description #1 34.00' 105 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 34.00 13 0 0 42.10 13 105 105 Device Routing Invert Outlet Devices #1 Discarded 34.00'2.000 in/hr Exfiltration over Surface area #2 Primary 42.00'20.0' long x 60.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 Discarded OutFlow Max=0.0 cfs @ 10.10 hrs HW=34.11' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.0 cfs) Primary OutFlow Max=0.9 cfs @ 12.11 hrs HW=42.07' TW=0.00' (Dynamic Tailwater) 2=Broad-Crested Rectangular Weir (Weir Controls 0.9 cfs @ 0.7 fps) Summary for Link A: LOT 48-62 Inflow Area = 62,933 sf, 40.15% Impervious, Inflow Depth > 0.92" for 2-YR event Inflow = 1.4 cfs @ 12.12 hrs, Volume= 4,840 cf Primary = 1.4 cfs @ 12.12 hrs, Volume= 4,840 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Link B: MAIN ST ROW Inflow Area = 30,599 sf, 59.52% Impervious, Inflow Depth > 1.20" for 2-YR event Inflow = 1.0 cfs @ 12.11 hrs, Volume= 3,056 cf Primary = 1.0 cfs @ 12.11 hrs, Volume= 3,056 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Link C: LOT 48-60 Inflow Area = 3,189 sf, 0.00% Impervious, Inflow Depth = 0.00" for 2-YR event Inflow = 0.0 cfs @ 0.00 hrs, Volume= 0 cf Primary = 0.0 cfs @ 0.00 hrs, Volume= 0 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73"31848-01 Pre-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 4HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: SUBCAT 1 Runoff = 1.2 cfs @ 12.11 hrs, Volume= 4,114 cf, Depth> 1.54" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 6,758 98 Roofs, HSG A 12,670 39 >75% Grass cover, Good, HSG A 5,730 96 Gravel surface, HSG A 3,123 30 Woods, Good, HSG A 196 98 Roofs, HSG C 1,088 74 >75% Grass cover, Good, HSG C 694 70 Woods, Good, HSG C 1,709 96 Gravel surface, HSG C 31,968 66 Weighted Average 25,014 78.25% Pervious Area 6,954 21.75% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.9 97 0.0900 0.3 Sheet Flow, 1a Grass: Short n= 0.150 P2= 2.54" 0.6 99 0.0300 2.8 Shallow Concentrated Flow, 1b Unpaved Kv= 16.1 fps 6.5 196 Total Summary for Subcatchment 2S: SUBCAT 2 Runoff = 0.0 cfs @ 12.11 hrs, Volume= 26 cf, Depth> 0.85" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 102 98 Paved parking, HSG A 264 39 >75% Grass cover, Good, HSG A 366 55 Weighted Average 264 72.13% Pervious Area 102 27.87% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 3S: SUBCAT 3 Runoff = 0.0 cfs @ 12.10 hrs, Volume= 46 cf, Depth> 1.34" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 164 98 Paved parking, HSG A 246 39 >75% Grass cover, Good, HSG A 410 63 Weighted Average 246 60.00% Pervious Area 164 40.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 4S: SUBCAT 4 Runoff = 1.8 cfs @ 12.11 hrs, Volume= 6,016 cf, Depth> 2.48" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 15,710 98 Paved parking, HSG A 2,339 98 Roofs, HSG A 9,836 39 >75% Grass cover, Good, HSG A 1,212 96 Gravel surface, HSG A 29,097 78 Weighted Average 11,048 37.97% Pervious Area 18,049 62.03% Impervious Area Type III 24-hr 10-YR Rainfall=4.73"31848-01 Pre-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 5HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.4 71 0.0600 0.2 Sheet Flow, 4a Grass: Short n= 0.150 P2= 2.54" 0.4 79 0.0500 3.6 Shallow Concentrated Flow, 4b Unpaved Kv= 16.1 fps 1.1 47 0.0100 0.7 Shallow Concentrated Flow, 4c Short Grass Pasture Kv= 7.0 fps 0.0 9 0.2700 3.6 Shallow Concentrated Flow, 4d Short Grass Pasture Kv= 7.0 fps 0.3 70 0.0300 3.5 Shallow Concentrated Flow, 4e Paved Kv= 20.3 fps 7.2 276 Total Summary for Subcatchment 5S: SUBCAT 5 Runoff = 0.0 cfs @ 13.74 hrs, Volume= 13 cf, Depth> 0.15" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 1,092 39 >75% Grass cover, Good, HSG A 1,092 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 6S: SUBCAT 6 Runoff = 0.0 cfs @ 14.93 hrs, Volume= 25 cf, Depth> 0.10" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 2,355 39 >75% Grass cover, Good, HSG A 834 30 Woods, Good, HSG A 3,189 37 Weighted Average 3,189 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Reach 1R: EX. DRAINAGE Inflow Area = 30,599 sf, 59.52% Impervious, Inflow Depth > 2.33" for 10-YR event Inflow = 1.8 cfs @ 12.11 hrs, Volume= 5,937 cf Outflow = 1.8 cfs @ 12.12 hrs, Volume= 5,934 cf, Atten= 0%, Lag= 0.6 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.8 fps, Min. Travel Time= 0.7 min Avg. Velocity = 1.3 fps, Avg. Travel Time= 1.6 min Peak Storage= 81 cf @ 12.12 hrs Average Depth at Peak Storage= 0.27' Bank-Full Depth= 1.00' Flow Area= 9.0 sf, Capacity= 60.5 cfs 0.00' x 1.00' deep channel, n= 0.050 Scattered brush, heavy weeds Side Slope Z-value= 9.0 '/' Top Width= 18.00' Length= 124.0' Slope= 0.1298 '/' Inlet Invert= 40.00', Outlet Invert= 23.90' ‡ Summary for Pond 7P: EX. CB [93] Warning: Storage range exceeded by 0.01' [87] Warning: Oscillations may require smaller dt or Finer Routing (severity=10) Inflow Area = 29,097 sf, 62.03% Impervious, Inflow Depth > 2.48" for 10-YR event Inflow = 1.8 cfs @ 12.11 hrs, Volume= 6,016 cf Outflow = 1.8 cfs @ 12.11 hrs, Volume= 5,912 cf, Atten= 0%, Lag= 0.0 min Discarded = 0.0 cfs @ 8.65 hrs, Volume= 34 cf Primary = 1.8 cfs @ 12.11 hrs, Volume= 5,878 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73"31848-01 Pre-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 6HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Peak Elev= 42.11' @ 12.11 hrs Surf.Area= 13 sf Storage= 105 cf Plug-Flow detention time= 14.4 min calculated for 5,912 cf (98% of inflow) Center-of-Mass det. time= 4.3 min ( 834.4 - 830.0 ) Volume Invert Avail.Storage Storage Description #1 34.00' 105 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 34.00 13 0 0 42.10 13 105 105 Device Routing Invert Outlet Devices #1 Discarded 34.00'2.000 in/hr Exfiltration over Surface area #2 Primary 42.00'20.0' long x 60.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63 Discarded OutFlow Max=0.0 cfs @ 8.65 hrs HW=34.11' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.0 cfs) Primary OutFlow Max=1.8 cfs @ 12.11 hrs HW=42.10' TW=0.00' (Dynamic Tailwater) 2=Broad-Crested Rectangular Weir (Weir Controls 1.8 cfs @ 0.9 fps) Summary for Link A: LOT 48-62 Inflow Area = 62,933 sf, 40.15% Impervious, Inflow Depth > 1.92" for 10-YR event Inflow = 3.1 cfs @ 12.11 hrs, Volume= 10,074 cf Primary = 3.1 cfs @ 12.11 hrs, Volume= 10,074 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Link B: MAIN ST ROW Inflow Area = 30,599 sf, 59.52% Impervious, Inflow Depth > 2.33" for 10-YR event Inflow = 1.8 cfs @ 12.11 hrs, Volume= 5,937 cf Primary = 1.8 cfs @ 12.11 hrs, Volume= 5,937 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Link C: LOT 48-60 Inflow Area = 3,189 sf, 0.00% Impervious, Inflow Depth > 0.10" for 10-YR event Inflow = 0.0 cfs @ 14.93 hrs, Volume= 25 cf Primary = 0.0 cfs @ 14.93 hrs, Volume= 25 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs 1S SUBCAT 1 2S SUBCAT 2 3S SUBCAT 3 4S SUBCAT 4 5S SUBCAT 5 6S SUBCAT 6 7S SUBCAT 7 8S SUBCAT 8 9S SUBCAT 9 10S SUBCAT 10 11S SUBCAT 11 12S SUBCAT 12 1R EX. DRAINAGE 1P ST.TECH-740 3P ISOLATOR CB1 CB CB2 CB CB3 CB CB4 CB CB5 CB CB7 CB A LOT 48-62 WETLAND B MAIN ST ROW C LOT 48-60 Routing Diagram for 31848-01 Post-Development_2020-01-30 Prepared by Microsoft, Printed 1/29/2020 HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Subcat Reach Pond Link 31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 2HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (sq-ft) CN Description (subcatchment-numbers) 19,357 39 >75% Grass cover, Good, HSG A (1S, 2S, 3S, 4S, 5S, 6S, 7S, 8S, 9S) 1,827 74 >75% Grass cover, Good, HSG C (1S) 29,066 98 Paved parking, HSG A (1S, 4S, 5S, 6S, 7S, 8S, 9S, 10S, 11S, 12S) 1,711 98 Paved parking, HSG C (1S, 10S, 12S) 10,566 98 Roofs, HSG A (1S, 4S, 7S, 8S, 9S, 11S) 3,446 30 Woods, Good, HSG A (1S, 2S, 4S) 149 70 Woods, Good, HSG C (1S) 66,122 76 TOTAL AREA 31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 3HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Soil Listing (all nodes) Area (sq-ft) Soil Group Subcatchment Numbers 62,435 HSG A 1S, 2S, 3S, 4S, 5S, 6S, 7S, 8S, 9S, 10S, 11S, 12S 0 HSG B 3,687 HSG C 1S, 10S, 12S 0 HSG D 0 Other 66,122 TOTAL AREA Type III 24-hr 2-YR Rainfall=3.25"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 4HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=13,402 sf 20.37% Impervious Runoff Depth>0.24"Subcatchment 1S: SUBCAT 1 Flow Length=100' Tc=11.8 min CN=54 Runoff=0.0 cfs 264 cf Runoff Area=1,299 sf 0.00% Impervious Runoff Depth=0.00"Subcatchment 2S: SUBCAT 2 Tc=6.0 min CN=33 Runoff=0.0 cfs 0 cf Runoff Area=895 sf 0.00% Impervious Runoff Depth>0.00"Subcatchment 3S: SUBCAT 3 Tc=6.0 min CN=39 Runoff=0.0 cfs 0 cf Runoff Area=10,201 sf 83.19% Impervious Runoff Depth>2.04"Subcatchment 4S: SUBCAT 4 Flow Length=198' Tc=6.7 min CN=88 Runoff=0.5 cfs 1,734 cf Runoff Area=2,167 sf 24.73% Impervious Runoff Depth>0.24"Subcatchment 5S: SUBCAT 5 Tc=6.0 min CN=54 Runoff=0.0 cfs 43 cf Runoff Area=4,099 sf 86.05% Impervious Runoff Depth>2.21"Subcatchment 6S: SUBCAT 6 Tc=6.0 min CN=90 Runoff=0.2 cfs 756 cf Runoff Area=18,929 sf 64.46% Impervious Runoff Depth>1.24"Subcatchment 7S: SUBCAT 7 Flow Length=291' Tc=12.0 min CN=77 Runoff=0.5 cfs 1,963 cf Runoff Area=2,883 sf 87.10% Impervious Runoff Depth>2.21"Subcatchment 8S: SUBCAT 8 Tc=6.0 min CN=90 Runoff=0.2 cfs 532 cf Runoff Area=6,677 sf 86.60% Impervious Runoff Depth>2.21"Subcatchment 9S: SUBCAT 9 Tc=6.0 min CN=90 Runoff=0.4 cfs 1,231 cf Runoff Area=1,368 sf 100.00% Impervious Runoff Depth>3.02"Subcatchment 10S: SUBCAT 10 Tc=6.0 min CN=98 Runoff=0.1 cfs 344 cf Runoff Area=1,668 sf 100.00% Impervious Runoff Depth>3.02"Subcatchment 11S: SUBCAT 11 Tc=6.0 min CN=98 Runoff=0.1 cfs 419 cf Runoff Area=2,534 sf 100.00% Impervious Runoff Depth>3.02"Subcatchment 12S: SUBCAT 12 Tc=6.0 min CN=98 Runoff=0.2 cfs 637 cf Avg. Flow Depth=0.19' Max Vel=2.2 fps Inflow=0.7 cfs 2,762 cfReach 1R: EX. DRAINAGE n=0.050 L=124.0' S=0.1298 '/' Capacity=60.5 cfs Outflow=0.7 cfs 2,760 cf Peak Elev=40.38' Storage=1,536 cf Inflow=1.5 cfs 4,897 cfPond 1P: ST.TECH-740 Discarded=0.2 cfs 4,897 cf Primary=0.0 cfs 0 cf Outflow=0.2 cfs 4,897 cf Peak Elev=0.00' Storage=0 cfPond 3P: ISOLATOR Peak Elev=44.91' Inflow=0.1 cfs 419 cfPond CB1: 8.0" Round Culvert n=0.013 L=32.0' S=0.0094 '/' Outflow=0.1 cfs 419 cf Peak Elev=44.40' Inflow=0.3 cfs 1,056 cfPond CB2: 12.0" Round Culvert n=0.013 L=57.0' S=0.0105 '/' Outflow=0.3 cfs 1,056 cf Peak Elev=43.75' Inflow=0.4 cfs 1,400 cfPond CB3: 12.0" Round Culvert n=0.013 L=48.0' S=0.0292 '/' Outflow=0.4 cfs 1,400 cf Peak Elev=42.41' Inflow=0.8 cfs 2,631 cfPond CB4: 12.0" Round Culvert n=0.013 L=46.0' S=0.0109 '/' Outflow=0.8 cfs 2,631 cf Peak Elev=41.87' Inflow=0.9 cfs 3,163 cfPond CB5: 12.0" Round Culvert n=0.013 L=44.0' S=0.0159 '/' Outflow=0.9 cfs 3,163 cf Peak Elev=41.25' Inflow=0.5 cfs 1,734 cfPond CB7: 12.0" Round Culvert n=0.013 L=41.0' S=0.0049 '/' Outflow=0.5 cfs 1,734 cf Inflow=0.7 cfs 3,024 cfLink A: LOT 48-62 WETLAND Primary=0.7 cfs 3,024 cf Inflow=0.7 cfs 2,762 cfLink B: MAIN ST ROW Primary=0.7 cfs 2,762 cf Inflow=0.0 cfs 0 cfLink C: LOT 48-60 Primary=0.0 cfs 0 cf Total Runoff Area = 66,122 sf Runoff Volume = 7,923 cf Average Runoff Depth = 1.44" 37.47% Pervious = 24,779 sf 62.53% Impervious = 41,343 sf Type III 24-hr 10-YR Rainfall=4.73"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 5HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=13,402 sf 20.37% Impervious Runoff Depth>0.79"Subcatchment 1S: SUBCAT 1 Flow Length=100' Tc=11.8 min CN=54 Runoff=0.2 cfs 883 cf Runoff Area=1,299 sf 0.00% Impervious Runoff Depth>0.02"Subcatchment 2S: SUBCAT 2 Tc=6.0 min CN=33 Runoff=0.0 cfs 2 cf Runoff Area=895 sf 0.00% Impervious Runoff Depth>0.15"Subcatchment 3S: SUBCAT 3 Tc=6.0 min CN=39 Runoff=0.0 cfs 11 cf Runoff Area=10,201 sf 83.19% Impervious Runoff Depth>3.41"Subcatchment 4S: SUBCAT 4 Flow Length=198' Tc=6.7 min CN=88 Runoff=0.9 cfs 2,899 cf Runoff Area=2,167 sf 24.73% Impervious Runoff Depth>0.79"Subcatchment 5S: SUBCAT 5 Tc=6.0 min CN=54 Runoff=0.0 cfs 143 cf Runoff Area=4,099 sf 86.05% Impervious Runoff Depth>3.61"Subcatchment 6S: SUBCAT 6 Tc=6.0 min CN=90 Runoff=0.4 cfs 1,234 cf Runoff Area=18,929 sf 64.46% Impervious Runoff Depth>2.39"Subcatchment 7S: SUBCAT 7 Flow Length=291' Tc=12.0 min CN=77 Runoff=1.0 cfs 3,775 cf Runoff Area=2,883 sf 87.10% Impervious Runoff Depth>3.61"Subcatchment 8S: SUBCAT 8 Tc=6.0 min CN=90 Runoff=0.3 cfs 868 cf Runoff Area=6,677 sf 86.60% Impervious Runoff Depth>3.61"Subcatchment 9S: SUBCAT 9 Tc=6.0 min CN=90 Runoff=0.6 cfs 2,011 cf Runoff Area=1,368 sf 100.00% Impervious Runoff Depth>4.49"Subcatchment 10S: SUBCAT 10 Tc=6.0 min CN=98 Runoff=0.1 cfs 512 cf Runoff Area=1,668 sf 100.00% Impervious Runoff Depth>4.49"Subcatchment 11S: SUBCAT 11 Tc=6.0 min CN=98 Runoff=0.2 cfs 624 cf Runoff Area=2,534 sf 100.00% Impervious Runoff Depth>4.49"Subcatchment 12S: SUBCAT 12 Tc=6.0 min CN=98 Runoff=0.3 cfs 948 cf Avg. Flow Depth=0.24' Max Vel=2.6 fps Inflow=1.3 cfs 5,153 cfReach 1R: EX. DRAINAGE n=0.050 L=124.0' S=0.1298 '/' Capacity=60.5 cfs Outflow=1.3 cfs 5,150 cf Peak Elev=41.54' Storage=2,908 cf Inflow=2.3 cfs 7,862 cfPond 1P: ST.TECH-740 Discarded=0.2 cfs 7,707 cf Primary=0.0 cfs 157 cf Outflow=0.2 cfs 7,864 cf Peak Elev=0.00' Storage=0 cfPond 3P: ISOLATOR Peak Elev=44.96' Inflow=0.2 cfs 624 cfPond CB1: 8.0" Round Culvert n=0.013 L=32.0' S=0.0094 '/' Outflow=0.2 cfs 624 cf Peak Elev=44.47' Inflow=0.4 cfs 1,573 cfPond CB2: 12.0" Round Culvert n=0.013 L=57.0' S=0.0105 '/' Outflow=0.4 cfs 1,573 cf Peak Elev=43.83' Inflow=0.6 cfs 2,085 cfPond CB3: 12.0" Round Culvert n=0.013 L=48.0' S=0.0292 '/' Outflow=0.6 cfs 2,085 cf Peak Elev=42.56' Inflow=1.2 cfs 4,095 cfPond CB4: 12.0" Round Culvert n=0.013 L=46.0' S=0.0109 '/' Outflow=1.2 cfs 4,095 cf Peak Elev=42.05' Inflow=1.5 cfs 4,963 cfPond CB5: 12.0" Round Culvert n=0.013 L=44.0' S=0.0159 '/' Outflow=1.5 cfs 4,963 cf Peak Elev=41.54' Inflow=0.9 cfs 2,899 cfPond CB7: 12.0" Round Culvert n=0.013 L=41.0' S=0.0049 '/' Outflow=0.9 cfs 2,899 cf Inflow=1.5 cfs 6,190 cfLink A: LOT 48-62 WETLAND Primary=1.5 cfs 6,190 cf Inflow=1.3 cfs 5,153 cfLink B: MAIN ST ROW Primary=1.3 cfs 5,153 cf Inflow=0.0 cfs 13 cfLink C: LOT 48-60 Primary=0.0 cfs 13 cf Total Runoff Area = 66,122 sf Runoff Volume = 13,911 cf Average Runoff Depth = 2.52" 37.47% Pervious = 24,779 sf 62.53% Impervious = 41,343 sf Type III 24-hr 25-YR Rainfall=5.87"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 6HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=13,402 sf 20.37% Impervious Runoff Depth>1.36"Subcatchment 1S: SUBCAT 1 Flow Length=100' Tc=11.8 min CN=54 Runoff=0.3 cfs 1,523 cf Runoff Area=1,299 sf 0.00% Impervious Runoff Depth>0.15"Subcatchment 2S: SUBCAT 2 Tc=6.0 min CN=33 Runoff=0.0 cfs 16 cf Runoff Area=895 sf 0.00% Impervious Runoff Depth>0.41"Subcatchment 3S: SUBCAT 3 Tc=6.0 min CN=39 Runoff=0.0 cfs 30 cf Runoff Area=10,201 sf 83.19% Impervious Runoff Depth>4.50"Subcatchment 4S: SUBCAT 4 Flow Length=198' Tc=6.7 min CN=88 Runoff=1.1 cfs 3,823 cf Runoff Area=2,167 sf 24.73% Impervious Runoff Depth>1.37"Subcatchment 5S: SUBCAT 5 Tc=6.0 min CN=54 Runoff=0.1 cfs 247 cf Runoff Area=4,099 sf 86.05% Impervious Runoff Depth>4.72"Subcatchment 6S: SUBCAT 6 Tc=6.0 min CN=90 Runoff=0.5 cfs 1,611 cf Runoff Area=18,929 sf 64.46% Impervious Runoff Depth>3.36"Subcatchment 7S: SUBCAT 7 Flow Length=291' Tc=12.0 min CN=77 Runoff=1.4 cfs 5,298 cf Runoff Area=2,883 sf 87.10% Impervious Runoff Depth>4.72"Subcatchment 8S: SUBCAT 8 Tc=6.0 min CN=90 Runoff=0.3 cfs 1,133 cf Runoff Area=6,677 sf 86.60% Impervious Runoff Depth>4.72"Subcatchment 9S: SUBCAT 9 Tc=6.0 min CN=90 Runoff=0.8 cfs 2,624 cf Runoff Area=1,368 sf 100.00% Impervious Runoff Depth>5.63"Subcatchment 10S: SUBCAT 10 Tc=6.0 min CN=98 Runoff=0.2 cfs 642 cf Runoff Area=1,668 sf 100.00% Impervious Runoff Depth>5.63"Subcatchment 11S: SUBCAT 11 Tc=6.0 min CN=98 Runoff=0.2 cfs 782 cf Runoff Area=2,534 sf 100.00% Impervious Runoff Depth>5.63"Subcatchment 12S: SUBCAT 12 Tc=6.0 min CN=98 Runoff=0.3 cfs 1,189 cf Avg. Flow Depth=0.27' Max Vel=2.8 fps Inflow=1.8 cfs 7,156 cfReach 1R: EX. DRAINAGE n=0.050 L=124.0' S=0.1298 '/' Capacity=60.5 cfs Outflow=1.8 cfs 7,153 cf Peak Elev=42.17' Storage=3,409 cf Inflow=3.0 cfs 10,193 cfPond 1P: ST.TECH-740 Discarded=0.2 cfs 8,891 cf Primary=0.8 cfs 1,302 cf Outflow=1.0 cfs 10,194 cf Peak Elev=0.00' Storage=0 cfPond 3P: ISOLATOR Peak Elev=44.99' Inflow=0.2 cfs 782 cfPond CB1: 8.0" Round Culvert n=0.013 L=32.0' S=0.0094 '/' Outflow=0.2 cfs 782 cf Peak Elev=44.52' Inflow=0.5 cfs 1,971 cfPond CB2: 12.0" Round Culvert n=0.013 L=57.0' S=0.0105 '/' Outflow=0.5 cfs 1,971 cf Peak Elev=43.89' Inflow=0.7 cfs 2,613 cfPond CB3: 12.0" Round Culvert n=0.013 L=48.0' S=0.0292 '/' Outflow=0.7 cfs 2,613 cf Peak Elev=42.66' Inflow=1.5 cfs 5,237 cfPond CB4: 12.0" Round Culvert n=0.013 L=46.0' S=0.0109 '/' Outflow=1.5 cfs 5,237 cf Peak Elev=42.21' Inflow=1.9 cfs 6,370 cfPond CB5: 12.0" Round Culvert n=0.013 L=44.0' S=0.0159 '/' Outflow=1.9 cfs 6,370 cf Peak Elev=42.18' Inflow=1.1 cfs 3,823 cfPond CB7: 12.0" Round Culvert n=0.013 L=41.0' S=0.0049 '/' Outflow=1.1 cfs 3,823 cf Inflow=2.2 cfs 9,978 cfLink A: LOT 48-62 WETLAND Primary=2.2 cfs 9,978 cf Inflow=1.8 cfs 7,156 cfLink B: MAIN ST ROW Primary=1.8 cfs 7,156 cf Inflow=0.0 cfs 46 cfLink C: LOT 48-60 Primary=0.0 cfs 46 cf Total Runoff Area = 66,122 sf Runoff Volume = 18,918 cf Average Runoff Depth = 3.43" 37.47% Pervious = 24,779 sf 62.53% Impervious = 41,343 sf Type III 24-hr 100-YR Rainfall=8.14"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 7HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=13,402 sf 20.37% Impervious Runoff Depth>2.76"Subcatchment 1S: SUBCAT 1 Flow Length=100' Tc=11.8 min CN=54 Runoff=0.8 cfs 3,085 cf Runoff Area=1,299 sf 0.00% Impervious Runoff Depth>0.68"Subcatchment 2S: SUBCAT 2 Tc=6.0 min CN=33 Runoff=0.0 cfs 74 cf Runoff Area=895 sf 0.00% Impervious Runoff Depth>1.21"Subcatchment 3S: SUBCAT 3 Tc=6.0 min CN=39 Runoff=0.0 cfs 91 cf Runoff Area=10,201 sf 83.19% Impervious Runoff Depth>6.70"Subcatchment 4S: SUBCAT 4 Flow Length=198' Tc=6.7 min CN=88 Runoff=1.7 cfs 5,695 cf Runoff Area=2,167 sf 24.73% Impervious Runoff Depth>2.77"Subcatchment 5S: SUBCAT 5 Tc=6.0 min CN=54 Runoff=0.2 cfs 500 cf Runoff Area=4,099 sf 86.05% Impervious Runoff Depth>6.94"Subcatchment 6S: SUBCAT 6 Tc=6.0 min CN=90 Runoff=0.7 cfs 2,370 cf Runoff Area=18,929 sf 64.46% Impervious Runoff Depth>5.39"Subcatchment 7S: SUBCAT 7 Flow Length=291' Tc=12.0 min CN=77 Runoff=2.2 cfs 8,506 cf Runoff Area=2,883 sf 87.10% Impervious Runoff Depth>6.94"Subcatchment 8S: SUBCAT 8 Tc=6.0 min CN=90 Runoff=0.5 cfs 1,667 cf Runoff Area=6,677 sf 86.60% Impervious Runoff Depth>6.94"Subcatchment 9S: SUBCAT 9 Tc=6.0 min CN=90 Runoff=1.1 cfs 3,861 cf Runoff Area=1,368 sf 100.00% Impervious Runoff Depth>7.90"Subcatchment 10S: SUBCAT 10 Tc=6.0 min CN=98 Runoff=0.2 cfs 900 cf Runoff Area=1,668 sf 100.00% Impervious Runoff Depth>7.90"Subcatchment 11S: SUBCAT 11 Tc=6.0 min CN=98 Runoff=0.3 cfs 1,097 cf Runoff Area=2,534 sf 100.00% Impervious Runoff Depth>7.90"Subcatchment 12S: SUBCAT 12 Tc=6.0 min CN=98 Runoff=0.5 cfs 1,667 cf Avg. Flow Depth=0.32' Max Vel=3.1 fps Inflow=2.9 cfs 11,376 cfReach 1R: EX. DRAINAGE n=0.050 L=124.0' S=0.1298 '/' Capacity=60.5 cfs Outflow=2.9 cfs 11,372 cf Peak Elev=43.32' Storage=3,633 cf Inflow=4.3 cfs 14,888 cfPond 1P: ST.TECH-740 Discarded=0.2 cfs 10,604 cf Primary=4.1 cfs 4,283 cf Outflow=4.3 cfs 14,887 cf Peak Elev=0.00' Storage=0 cfPond 3P: ISOLATOR Peak Elev=45.05' Inflow=0.3 cfs 1,097 cfPond CB1: 8.0" Round Culvert n=0.013 L=32.0' S=0.0094 '/' Outflow=0.3 cfs 1,097 cf Peak Elev=44.60' Inflow=0.8 cfs 2,765 cfPond CB2: 12.0" Round Culvert n=0.013 L=57.0' S=0.0105 '/' Outflow=0.8 cfs 2,765 cf Peak Elev=43.99' Inflow=1.0 cfs 3,665 cfPond CB3: 12.0" Round Culvert n=0.013 L=48.0' S=0.0292 '/' Outflow=1.0 cfs 3,665 cf Peak Elev=43.69' Inflow=2.1 cfs 7,526 cfPond CB4: 12.0" Round Culvert n=0.013 L=46.0' S=0.0109 '/' Outflow=2.1 cfs 7,526 cf Peak Elev=43.58' Inflow=2.6 cfs 9,193 cfPond CB5: 12.0" Round Culvert n=0.013 L=44.0' S=0.0159 '/' Outflow=2.6 cfs 9,193 cf Peak Elev=43.44' Inflow=1.7 cfs 5,695 cfPond CB7: 12.0" Round Culvert n=0.013 L=41.0' S=0.0049 '/' Outflow=1.7 cfs 5,695 cf Inflow=7.8 cfs 18,740 cfLink A: LOT 48-62 WETLAND Primary=7.8 cfs 18,740 cf Inflow=2.9 cfs 11,376 cfLink B: MAIN ST ROW Primary=2.9 cfs 11,376 cf Inflow=0.0 cfs 164 cfLink C: LOT 48-60 Primary=0.0 cfs 164 cf Total Runoff Area = 66,122 sf Runoff Volume = 29,514 cf Average Runoff Depth = 5.36" 37.47% Pervious = 24,779 sf 62.53% Impervious = 41,343 sf Type III 24-hr 2-YR Rainfall=3.25"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 1HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: SUBCAT 1 Runoff = 0.0 cfs @ 12.44 hrs, Volume= 264 cf, Depth> 0.24" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 2,591 30 Woods, Good, HSG A 1,391 98 Roofs, HSG A 1,253 98 Paved parking, HSG A 6,105 39 >75% Grass cover, Good, HSG A 86 98 Paved parking, HSG C 149 70 Woods, Good, HSG C 1,827 74 >75% Grass cover, Good, HSG C 13,402 54 Weighted Average 10,672 79.63% Pervious Area 2,730 20.37% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.1 23 0.5000 3.3 Sheet Flow, 1a Smooth surfaces n= 0.011 P2= 2.54" 3.0 28 0.0400 0.2 Sheet Flow, 1b Grass: Short n= 0.150 P2= 2.54" 5.8 24 0.0400 0.1 Sheet Flow, 1c Woods: Light underbrush n= 0.400 P2= 2.54" 2.9 25 0.2400 0.1 Sheet Flow, 1d Woods: Light underbrush n= 0.400 P2= 2.54" 11.8 100 Total Summary for Subcatchment 2S: SUBCAT 2 [45] Hint: Runoff=Zero Runoff = 0.0 cfs @ 0.00 hrs, Volume= 0 cf, Depth= 0.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 505 39 >75% Grass cover, Good, HSG A 794 30 Woods, Good, HSG A 1,299 33 Weighted Average 1,299 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 3S: SUBCAT 3 [73] Warning: Peak may fall outside time span Runoff = 0.0 cfs @ 24.00 hrs, Volume= 0 cf, Depth> 0.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 895 39 >75% Grass cover, Good, HSG A 895 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 4S: SUBCAT 4 Runoff = 0.5 cfs @ 12.10 hrs, Volume= 1,734 cf, Depth> 2.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 6,011 98 Paved parking, HSG A 2,475 98 Roofs, HSG A 1,654 39 >75% Grass cover, Good, HSG A 61 30 Woods, Good, HSG A 10,201 88 Weighted Average 1,715 16.81% Pervious Area 8,486 83.19% Impervious Area Type III 24-hr 2-YR Rainfall=3.25"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 2HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 100 0.0900 0.3 Sheet Flow, 4a Grass: Short n= 0.150 P2= 2.54" 0.1 10 0.0200 2.9 Shallow Concentrated Flow, 4b Paved Kv= 20.3 fps 0.6 88 0.0150 2.5 Shallow Concentrated Flow, 4c Paved Kv= 20.3 fps 6.7 198 Total Summary for Subcatchment 5S: SUBCAT 5 Runoff = 0.0 cfs @ 12.35 hrs, Volume= 43 cf, Depth> 0.24" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 1,631 39 >75% Grass cover, Good, HSG A 536 98 Paved parking, HSG A 2,167 54 Weighted Average 1,631 75.27% Pervious Area 536 24.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 6S: SUBCAT 6 Runoff = 0.2 cfs @ 12.09 hrs, Volume= 756 cf, Depth> 2.21" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 572 39 >75% Grass cover, Good, HSG A 3,527 98 Paved parking, HSG A 4,099 90 Weighted Average 572 13.95% Pervious Area 3,527 86.05% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 7S: SUBCAT 7 Runoff = 0.5 cfs @ 12.18 hrs, Volume= 1,963 cf, Depth> 1.24" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 8,417 98 Paved parking, HSG A 3,784 98 Roofs, HSG A 6,728 39 >75% Grass cover, Good, HSG A 18,929 77 Weighted Average 6,728 35.54% Pervious Area 12,201 64.46% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.8 28 0.1500 0.3 Sheet Flow, 7a Grass: Short n= 0.150 P2= 2.54" 5.0 37 0.0200 0.1 Sheet Flow, 7b Grass: Short n= 0.150 P2= 2.54" 1.2 16 0.1300 0.2 Sheet Flow, 7c Grass: Short n= 0.150 P2= 2.54" 2.9 19 0.0200 0.1 Sheet Flow, 7d Grass: Short n= 0.150 P2= 2.54" 0.3 19 0.0200 1.0 Shallow Concentrated Flow, 7e Short Grass Pasture Kv= 7.0 fps 0.1 25 0.0300 3.5 Shallow Concentrated Flow, 7f Paved Kv= 20.3 fps 0.1 26 0.0300 3.5 Shallow Concentrated Flow, 7g Paved Kv= 20.3 fps 0.2 48 0.0400 4.1 Shallow Concentrated Flow, 7h Paved Kv= 20.3 fps 0.1 29 0.0300 3.5 Shallow Concentrated Flow, 7i Paved Kv= 20.3 fps 0.3 44 0.0200 2.9 Shallow Concentrated Flow, 7j Paved Kv= 20.3 fps 12.0 291 Total Type III 24-hr 2-YR Rainfall=3.25"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 3HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 8S: SUBCAT 8 Runoff = 0.2 cfs @ 12.09 hrs, Volume= 532 cf, Depth> 2.21" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 2,318 98 Paved parking, HSG A 193 98 Roofs, HSG A 372 39 >75% Grass cover, Good, HSG A 2,883 90 Weighted Average 372 12.90% Pervious Area 2,511 87.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 9S: SUBCAT 9 Runoff = 0.4 cfs @ 12.09 hrs, Volume= 1,231 cf, Depth> 2.21" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 4,486 98 Paved parking, HSG A 1,296 98 Roofs, HSG A 895 39 >75% Grass cover, Good, HSG A 6,677 90 Weighted Average 895 13.40% Pervious Area 5,782 86.60% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 10S: SUBCAT 10 Runoff = 0.1 cfs @ 12.09 hrs, Volume= 344 cf, Depth> 3.02" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 1,252 98 Paved parking, HSG A 116 98 Paved parking, HSG C 1,368 98 Weighted Average 1,368 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 11S: SUBCAT 11 Runoff = 0.1 cfs @ 12.09 hrs, Volume= 419 cf, Depth> 3.02" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 1,427 98 Roofs, HSG A 241 98 Paved parking, HSG A 1,668 98 Weighted Average 1,668 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 12S: SUBCAT 12 Runoff = 0.2 cfs @ 12.09 hrs, Volume= 637 cf, Depth> 3.02" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25" Area (sf) CN Description 1,025 98 Paved parking, HSG A 1,509 98 Paved parking, HSG C 2,534 98 Weighted Average 2,534 100.00% Impervious Area Type III 24-hr 2-YR Rainfall=3.25"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 4HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Reach 1R: EX. DRAINAGE Inflow Area = 25,195 sf, 64.55% Impervious, Inflow Depth > 1.32" for 2-YR event Inflow = 0.7 cfs @ 12.15 hrs, Volume= 2,762 cf Outflow = 0.7 cfs @ 12.16 hrs, Volume= 2,760 cf, Atten= 0%, Lag= 0.7 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.2 fps, Min. Travel Time= 0.9 min Avg. Velocity = 0.9 fps, Avg. Travel Time= 2.3 min Peak Storage= 39 cf @ 12.16 hrs Average Depth at Peak Storage= 0.19' Bank-Full Depth= 1.00' Flow Area= 9.0 sf, Capacity= 60.5 cfs 0.00' x 1.00' deep channel, n= 0.050 Scattered brush, heavy weeds Side Slope Z-value= 9.0 '/' Top Width= 18.00' Length= 124.0' Slope= 0.1298 '/' Inlet Invert= 40.00', Outlet Invert= 23.90' ‡ Summary for Pond 1P: ST.TECH-740 Inflow Area = 25,331 sf, 88.23% Impervious, Inflow Depth > 2.32" for 2-YR event Inflow = 1.5 cfs @ 12.09 hrs, Volume= 4,897 cf Outflow = 0.2 cfs @ 11.75 hrs, Volume= 4,897 cf, Atten= 87%, Lag= 0.0 min Discarded = 0.2 cfs @ 11.75 hrs, Volume= 4,897 cf Primary = 0.0 cfs @ 0.00 hrs, Volume= 0 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 40.38' @ 12.66 hrs Surf.Area= 1,709 sf Storage= 1,536 cf Flood Elev= 43.50' Surf.Area= 1,709 sf Storage= 3,633 cf Plug-Flow detention time= 52.0 min calculated for 4,886 cf (100% of inflow) Center-of-Mass det. time= 51.8 min ( 846.4 - 794.5 ) Volume Invert Avail.Storage Storage Description #1A 39.00' 1,566 cf 25.25'W x 67.70'L x 3.50'H Field A 5,983 cf Overall - 2,067 cf Embedded = 3,915 cf x 40.0% Voids #2A 39.50' 2,067 cf ADS_StormTech SC-740 +Cap x 45 Inside #1 Effective Size= 3.72?W x 2.5?H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 4.25?W x 2.5?H x 7.56'L with 0.44' Overlap 5 Rows of 9 Chambers 3,633 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Device 3 42.00'12.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2 Device 3 41.30'2.0" Vert. Orifice/Grate C= 0.600 #3 Primary 41.00'12.0" Round Culvert L= 62.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 41.00' / 40.38' S= 0.0100 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #4 Discarded 39.00'5.000 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.2 cfs @ 11.75 hrs HW=39.06' (Free Discharge) 4=Exfiltration (Exfiltration Controls 0.2 cfs) Primary OutFlow Max=0.0 cfs @ 0.00 hrs HW=39.00' TW=0.00' (Dynamic Tailwater) 3=Culvert ( Controls 0.0 cfs) 1=Orifice/Grate ( Controls 0.0 cfs) 2=Orifice/Grate ( Controls 0.0 cfs) Summary for Pond 3P: ISOLATOR [43] Hint: Has no inflow (Outflow=Zero) Volume Invert Avail.Storage Storage Description #1A 39.00' 1,566 cf 25.25'W x 67.70'L x 3.50'H Field A 5,983 cf Overall - 2,067 cf Embedded = 3,915 cf x 40.0% Voids #2A 39.50' 2,067 cf ADS_StormTech SC-740 +Cap x 45 Inside #1 Effective Size= 3.72?W x 2.5?H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 4.25?W x 2.5?H x 7.56'L with 0.44' Overlap 5 Rows of 9 Chambers 3,633 cf Total Available Storage Storage Group A created with Chamber Wizard Type III 24-hr 2-YR Rainfall=3.25"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 5HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Summary for Pond CB1: Inflow Area = 1,668 sf,100.00% Impervious, Inflow Depth > 3.02" for 2-YR event Inflow = 0.1 cfs @ 12.09 hrs, Volume= 419 cf Outflow = 0.1 cfs @ 12.09 hrs, Volume= 419 cf, Atten= 0%, Lag= 0.0 min Primary = 0.1 cfs @ 12.09 hrs, Volume= 419 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 44.91' @ 12.09 hrs Flood Elev= 48.40' Device Routing Invert Outlet Devices #1 Primary 44.70'8.0" Round Culvert L= 32.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 44.70' / 44.40' S= 0.0094 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf Primary OutFlow Max=0.1 cfs @ 12.09 hrs HW=44.91' TW=44.40' (Dynamic Tailwater) 1=Culvert (Inlet Controls 0.1 cfs @ 1.2 fps) Summary for Pond CB2: Inflow Area = 4,202 sf,100.00% Impervious, Inflow Depth > 3.02" for 2-YR event Inflow = 0.3 cfs @ 12.09 hrs, Volume= 1,056 cf Outflow = 0.3 cfs @ 12.09 hrs, Volume= 1,056 cf, Atten= 0%, Lag= 0.0 min Primary = 0.3 cfs @ 12.09 hrs, Volume= 1,056 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 44.40' @ 12.09 hrs Flood Elev= 49.70' Device Routing Invert Outlet Devices #1 Primary 44.10'12.0" Round Culvert L= 57.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 44.10' / 43.50' S= 0.0105 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=0.3 cfs @ 12.09 hrs HW=44.40' TW=43.75' (Dynamic Tailwater) 1=Culvert (Inlet Controls 0.3 cfs @ 1.5 fps) Summary for Pond CB3: Inflow Area = 5,570 sf,100.00% Impervious, Inflow Depth > 3.02" for 2-YR event Inflow = 0.4 cfs @ 12.09 hrs, Volume= 1,400 cf Outflow = 0.4 cfs @ 12.09 hrs, Volume= 1,400 cf, Atten= 0%, Lag= 0.0 min Primary = 0.4 cfs @ 12.09 hrs, Volume= 1,400 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 43.75' @ 12.09 hrs Flood Elev= 47.90' Device Routing Invert Outlet Devices #1 Primary 43.40'12.0" Round Culvert L= 48.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 43.40' / 42.00' S= 0.0292 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=0.4 cfs @ 12.09 hrs HW=43.75' TW=42.40' (Dynamic Tailwater) 1=Culvert (Inlet Controls 0.4 cfs @ 1.6 fps) Summary for Pond CB4: Inflow Area = 12,247 sf, 92.69% Impervious, Inflow Depth > 2.58" for 2-YR event Inflow = 0.8 cfs @ 12.09 hrs, Volume= 2,631 cf Outflow = 0.8 cfs @ 12.09 hrs, Volume= 2,631 cf, Atten= 0%, Lag= 0.0 min Primary = 0.8 cfs @ 12.09 hrs, Volume= 2,631 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 42.41' @ 12.09 hrs Flood Elev= 46.00' Device Routing Invert Outlet Devices #1 Primary 41.90'12.0" Round Culvert L= 46.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 41.90' / 41.40' S= 0.0109 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=0.8 cfs @ 12.09 hrs HW=42.40' TW=41.86' (Dynamic Tailwater) 1=Culvert (Inlet Controls 0.8 cfs @ 1.9 fps) Summary for Pond CB5: Inflow Area = 15,130 sf, 91.63% Impervious, Inflow Depth > 2.51" for 2-YR event Inflow = 0.9 cfs @ 12.09 hrs, Volume= 3,163 cf Outflow = 0.9 cfs @ 12.09 hrs, Volume= 3,163 cf, Atten= 0%, Lag= 0.0 min Primary = 0.9 cfs @ 12.09 hrs, Volume= 3,163 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-YR Rainfall=3.25"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 6HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Peak Elev= 41.87' @ 12.09 hrs Flood Elev= 45.30' Device Routing Invert Outlet Devices #1 Primary 41.30'12.0" Round Culvert L= 44.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 41.30' / 40.60' S= 0.0159 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=0.9 cfs @ 12.09 hrs HW=41.86' TW=39.75' (Dynamic Tailwater) 1=Culvert (Inlet Controls 0.9 cfs @ 2.0 fps) Summary for Pond CB7: Inflow Area = 10,201 sf, 83.19% Impervious, Inflow Depth > 2.04" for 2-YR event Inflow = 0.5 cfs @ 12.10 hrs, Volume= 1,734 cf Outflow = 0.5 cfs @ 12.10 hrs, Volume= 1,734 cf, Atten= 0%, Lag= 0.0 min Primary = 0.5 cfs @ 12.10 hrs, Volume= 1,734 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 41.25' @ 12.10 hrs Flood Elev= 43.80' Device Routing Invert Outlet Devices #1 Primary 40.80'12.0" Round Culvert L= 41.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 40.80' / 40.60' S= 0.0049 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=0.5 cfs @ 12.10 hrs HW=41.25' TW=39.78' (Dynamic Tailwater) 1=Culvert (Barrel Controls 0.5 cfs @ 2.3 fps) Summary for Link A: LOT 48-62 WETLAND Inflow Area = 63,928 sf, 64.67% Impervious, Inflow Depth > 0.57" for 2-YR event Inflow = 0.7 cfs @ 12.16 hrs, Volume= 3,024 cf Primary = 0.7 cfs @ 12.16 hrs, Volume= 3,024 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Link B: MAIN ST ROW Inflow Area = 25,195 sf, 64.55% Impervious, Inflow Depth > 1.32" for 2-YR event Inflow = 0.7 cfs @ 12.15 hrs, Volume= 2,762 cf Primary = 0.7 cfs @ 12.15 hrs, Volume= 2,762 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Link C: LOT 48-60 Inflow Area = 2,194 sf, 0.00% Impervious, Inflow Depth > 0.00" for 2-YR event Inflow = 0.0 cfs @ 24.00 hrs, Volume= 0 cf Primary = 0.0 cfs @ 24.00 hrs, Volume= 0 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 7HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: SUBCAT 1 Runoff = 0.2 cfs @ 12.21 hrs, Volume= 883 cf, Depth> 0.79" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 2,591 30 Woods, Good, HSG A 1,391 98 Roofs, HSG A 1,253 98 Paved parking, HSG A 6,105 39 >75% Grass cover, Good, HSG A 86 98 Paved parking, HSG C 149 70 Woods, Good, HSG C 1,827 74 >75% Grass cover, Good, HSG C 13,402 54 Weighted Average 10,672 79.63% Pervious Area 2,730 20.37% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.1 23 0.5000 3.3 Sheet Flow, 1a Smooth surfaces n= 0.011 P2= 2.54" 3.0 28 0.0400 0.2 Sheet Flow, 1b Grass: Short n= 0.150 P2= 2.54" 5.8 24 0.0400 0.1 Sheet Flow, 1c Woods: Light underbrush n= 0.400 P2= 2.54" 2.9 25 0.2400 0.1 Sheet Flow, 1d Woods: Light underbrush n= 0.400 P2= 2.54" 11.8 100 Total Summary for Subcatchment 2S: SUBCAT 2 Runoff = 0.0 cfs @ 21.39 hrs, Volume= 2 cf, Depth> 0.02" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 505 39 >75% Grass cover, Good, HSG A 794 30 Woods, Good, HSG A 1,299 33 Weighted Average 1,299 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 3S: SUBCAT 3 Runoff = 0.0 cfs @ 13.74 hrs, Volume= 11 cf, Depth> 0.15" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 895 39 >75% Grass cover, Good, HSG A 895 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 4S: SUBCAT 4 Runoff = 0.9 cfs @ 12.10 hrs, Volume= 2,899 cf, Depth> 3.41" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 6,011 98 Paved parking, HSG A 2,475 98 Roofs, HSG A 1,654 39 >75% Grass cover, Good, HSG A 61 30 Woods, Good, HSG A 10,201 88 Weighted Average 1,715 16.81% Pervious Area 8,486 83.19% Impervious Area Type III 24-hr 10-YR Rainfall=4.73"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 8HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 100 0.0900 0.3 Sheet Flow, 4a Grass: Short n= 0.150 P2= 2.54" 0.1 10 0.0200 2.9 Shallow Concentrated Flow, 4b Paved Kv= 20.3 fps 0.6 88 0.0150 2.5 Shallow Concentrated Flow, 4c Paved Kv= 20.3 fps 6.7 198 Total Summary for Subcatchment 5S: SUBCAT 5 Runoff = 0.0 cfs @ 12.12 hrs, Volume= 143 cf, Depth> 0.79" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 1,631 39 >75% Grass cover, Good, HSG A 536 98 Paved parking, HSG A 2,167 54 Weighted Average 1,631 75.27% Pervious Area 536 24.73% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 6S: SUBCAT 6 Runoff = 0.4 cfs @ 12.09 hrs, Volume= 1,234 cf, Depth> 3.61" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 572 39 >75% Grass cover, Good, HSG A 3,527 98 Paved parking, HSG A 4,099 90 Weighted Average 572 13.95% Pervious Area 3,527 86.05% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 7S: SUBCAT 7 Runoff = 1.0 cfs @ 12.17 hrs, Volume= 3,775 cf, Depth> 2.39" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 8,417 98 Paved parking, HSG A 3,784 98 Roofs, HSG A 6,728 39 >75% Grass cover, Good, HSG A 18,929 77 Weighted Average 6,728 35.54% Pervious Area 12,201 64.46% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.8 28 0.1500 0.3 Sheet Flow, 7a Grass: Short n= 0.150 P2= 2.54" 5.0 37 0.0200 0.1 Sheet Flow, 7b Grass: Short n= 0.150 P2= 2.54" 1.2 16 0.1300 0.2 Sheet Flow, 7c Grass: Short n= 0.150 P2= 2.54" 2.9 19 0.0200 0.1 Sheet Flow, 7d Grass: Short n= 0.150 P2= 2.54" 0.3 19 0.0200 1.0 Shallow Concentrated Flow, 7e Short Grass Pasture Kv= 7.0 fps 0.1 25 0.0300 3.5 Shallow Concentrated Flow, 7f Paved Kv= 20.3 fps 0.1 26 0.0300 3.5 Shallow Concentrated Flow, 7g Paved Kv= 20.3 fps 0.2 48 0.0400 4.1 Shallow Concentrated Flow, 7h Paved Kv= 20.3 fps 0.1 29 0.0300 3.5 Shallow Concentrated Flow, 7i Paved Kv= 20.3 fps 0.3 44 0.0200 2.9 Shallow Concentrated Flow, 7j Paved Kv= 20.3 fps 12.0 291 Total Type III 24-hr 10-YR Rainfall=4.73"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 9HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 8S: SUBCAT 8 Runoff = 0.3 cfs @ 12.09 hrs, Volume= 868 cf, Depth> 3.61" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 2,318 98 Paved parking, HSG A 193 98 Roofs, HSG A 372 39 >75% Grass cover, Good, HSG A 2,883 90 Weighted Average 372 12.90% Pervious Area 2,511 87.10% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 9S: SUBCAT 9 Runoff = 0.6 cfs @ 12.09 hrs, Volume= 2,011 cf, Depth> 3.61" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 4,486 98 Paved parking, HSG A 1,296 98 Roofs, HSG A 895 39 >75% Grass cover, Good, HSG A 6,677 90 Weighted Average 895 13.40% Pervious Area 5,782 86.60% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 10S: SUBCAT 10 Runoff = 0.1 cfs @ 12.09 hrs, Volume= 512 cf, Depth> 4.49" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 1,252 98 Paved parking, HSG A 116 98 Paved parking, HSG C 1,368 98 Weighted Average 1,368 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 11S: SUBCAT 11 Runoff = 0.2 cfs @ 12.09 hrs, Volume= 624 cf, Depth> 4.49" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 1,427 98 Roofs, HSG A 241 98 Paved parking, HSG A 1,668 98 Weighted Average 1,668 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Subcatchment 12S: SUBCAT 12 Runoff = 0.3 cfs @ 12.09 hrs, Volume= 948 cf, Depth> 4.49" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-YR Rainfall=4.73" Area (sf) CN Description 1,025 98 Paved parking, HSG A 1,509 98 Paved parking, HSG C 2,534 98 Weighted Average 2,534 100.00% Impervious Area Type III 24-hr 10-YR Rainfall=4.73"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 10HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Calc'd Tc<6 mins Summary for Reach 1R: EX. DRAINAGE Inflow Area = 25,195 sf, 64.55% Impervious, Inflow Depth > 2.45" for 10-YR event Inflow = 1.3 cfs @ 12.15 hrs, Volume= 5,153 cf Outflow = 1.3 cfs @ 12.16 hrs, Volume= 5,150 cf, Atten= 0%, Lag= 0.6 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Max. Velocity= 2.6 fps, Min. Travel Time= 0.8 min Avg. Velocity = 1.0 fps, Avg. Travel Time= 2.0 min Peak Storage= 63 cf @ 12.16 hrs Average Depth at Peak Storage= 0.24' Bank-Full Depth= 1.00' Flow Area= 9.0 sf, Capacity= 60.5 cfs 0.00' x 1.00' deep channel, n= 0.050 Scattered brush, heavy weeds Side Slope Z-value= 9.0 '/' Top Width= 18.00' Length= 124.0' Slope= 0.1298 '/' Inlet Invert= 40.00', Outlet Invert= 23.90' ‡ Summary for Pond 1P: ST.TECH-740 [87] Warning: Oscillations may require smaller dt or Finer Routing (severity=1) [80] Warning: Exceeded Pond CB7 by 0.04' @ 12.50 hrs (0.3 cfs 354 cf) Inflow Area = 25,331 sf, 88.23% Impervious, Inflow Depth > 3.72" for 10-YR event Inflow = 2.3 cfs @ 12.09 hrs, Volume= 7,862 cf Outflow = 0.2 cfs @ 12.89 hrs, Volume= 7,864 cf, Atten= 90%, Lag= 48.1 min Discarded = 0.2 cfs @ 11.60 hrs, Volume= 7,707 cf Primary = 0.0 cfs @ 12.89 hrs, Volume= 157 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 41.54' @ 12.89 hrs Surf.Area= 1,709 sf Storage= 2,908 cf Flood Elev= 43.50' Surf.Area= 1,709 sf Storage= 3,633 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= 108.0 min ( 891.5 - 783.5 ) Volume Invert Avail.Storage Storage Description #1A 39.00' 1,566 cf 25.25'W x 67.70'L x 3.50'H Field A 5,983 cf Overall - 2,067 cf Embedded = 3,915 cf x 40.0% Voids #2A 39.50' 2,067 cf ADS_StormTech SC-740 +Cap x 45 Inside #1 Effective Size= 3.72?W x 2.5?H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 4.25?W x 2.5?H x 7.56'L with 0.44' Overlap 5 Rows of 9 Chambers 3,633 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Device 3 42.00'12.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2 Device 3 41.30'2.0" Vert. Orifice/Grate C= 0.600 #3 Primary 41.00'12.0" Round Culvert L= 62.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 41.00' / 40.38' S= 0.0100 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #4 Discarded 39.00'5.000 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.2 cfs @ 11.60 hrs HW=39.06' (Free Discharge) 4=Exfiltration (Exfiltration Controls 0.2 cfs) Primary OutFlow Max=0.0 cfs @ 12.89 hrs HW=41.54' TW=0.00' (Dynamic Tailwater) 3=Culvert (Passes 0.0 cfs of 0.8 cfs potential flow) 1=Orifice/Grate ( Controls 0.0 cfs) 2=Orifice/Grate (Orifice Controls 0.0 cfs @ 1.9 fps) Summary for Pond 3P: ISOLATOR [43] Hint: Has no inflow (Outflow=Zero) Volume Invert Avail.Storage Storage Description #1A 39.00' 1,566 cf 25.25'W x 67.70'L x 3.50'H Field A 5,983 cf Overall - 2,067 cf Embedded = 3,915 cf x 40.0% Voids #2A 39.50' 2,067 cf ADS_StormTech SC-740 +Cap x 45 Inside #1 Effective Size= 3.72?W x 2.5?H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 4.25?W x 2.5?H x 7.56'L with 0.44' Overlap 5 Rows of 9 Chambers Type III 24-hr 10-YR Rainfall=4.73"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 11HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC 3,633 cf Total Available Storage Storage Group A created with Chamber Wizard Summary for Pond CB1: Inflow Area = 1,668 sf,100.00% Impervious, Inflow Depth > 4.49" for 10-YR event Inflow = 0.2 cfs @ 12.09 hrs, Volume= 624 cf Outflow = 0.2 cfs @ 12.09 hrs, Volume= 624 cf, Atten= 0%, Lag= 0.0 min Primary = 0.2 cfs @ 12.09 hrs, Volume= 624 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 44.96' @ 12.09 hrs Flood Elev= 48.40' Device Routing Invert Outlet Devices #1 Primary 44.70'8.0" Round Culvert L= 32.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 44.70' / 44.40' S= 0.0094 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf Primary OutFlow Max=0.2 cfs @ 12.09 hrs HW=44.96' TW=44.47' (Dynamic Tailwater) 1=Culvert (Inlet Controls 0.2 cfs @ 1.4 fps) Summary for Pond CB2: Inflow Area = 4,202 sf,100.00% Impervious, Inflow Depth > 4.49" for 10-YR event Inflow = 0.4 cfs @ 12.09 hrs, Volume= 1,573 cf Outflow = 0.4 cfs @ 12.09 hrs, Volume= 1,573 cf, Atten= 0%, Lag= 0.0 min Primary = 0.4 cfs @ 12.09 hrs, Volume= 1,573 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 44.47' @ 12.09 hrs Flood Elev= 49.70' Device Routing Invert Outlet Devices #1 Primary 44.10'12.0" Round Culvert L= 57.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 44.10' / 43.50' S= 0.0105 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=0.4 cfs @ 12.09 hrs HW=44.47' TW=43.83' (Dynamic Tailwater) 1=Culvert (Inlet Controls 0.4 cfs @ 1.6 fps) Summary for Pond CB3: Inflow Area = 5,570 sf,100.00% Impervious, Inflow Depth > 4.49" for 10-YR event Inflow = 0.6 cfs @ 12.09 hrs, Volume= 2,085 cf Outflow = 0.6 cfs @ 12.09 hrs, Volume= 2,085 cf, Atten= 0%, Lag= 0.0 min Primary = 0.6 cfs @ 12.09 hrs, Volume= 2,085 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 43.83' @ 12.09 hrs Flood Elev= 47.90' Device Routing Invert Outlet Devices #1 Primary 43.40'12.0" Round Culvert L= 48.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 43.40' / 42.00' S= 0.0292 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=0.6 cfs @ 12.09 hrs HW=43.83' TW=42.55' (Dynamic Tailwater) 1=Culvert (Inlet Controls 0.6 cfs @ 1.8 fps) Summary for Pond CB4: Inflow Area = 12,247 sf, 92.69% Impervious, Inflow Depth > 4.01" for 10-YR event Inflow = 1.2 cfs @ 12.09 hrs, Volume= 4,095 cf Outflow = 1.2 cfs @ 12.09 hrs, Volume= 4,095 cf, Atten= 0%, Lag= 0.0 min Primary = 1.2 cfs @ 12.09 hrs, Volume= 4,095 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 42.56' @ 12.09 hrs Flood Elev= 46.00' Device Routing Invert Outlet Devices #1 Primary 41.90'12.0" Round Culvert L= 46.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 41.90' / 41.40' S= 0.0109 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=1.2 cfs @ 12.09 hrs HW=42.55' TW=42.03' (Dynamic Tailwater) 1=Culvert (Inlet Controls 1.2 cfs @ 2.2 fps) Summary for Pond CB5: Inflow Area = 15,130 sf, 91.63% Impervious, Inflow Depth > 3.94" for 10-YR event Inflow = 1.5 cfs @ 12.09 hrs, Volume= 4,963 cf Outflow = 1.5 cfs @ 12.09 hrs, Volume= 4,963 cf, Atten= 0%, Lag= 0.0 min Primary = 1.5 cfs @ 12.09 hrs, Volume= 4,963 cf Type III 24-hr 10-YR Rainfall=4.73"31848-01 Post-Development_2020-01-30 Printed 1/29/2020Prepared by Microsoft Page 12HydroCAD® 10.00-19 s/n 00866 © 2016 HydroCAD Software Solutions LLC Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 42.05' @ 12.09 hrs Flood Elev= 45.30' Device Routing Invert Outlet Devices #1 Primary 41.30'12.0" Round Culvert L= 44.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 41.30' / 40.60' S= 0.0159 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=1.4 cfs @ 12.09 hrs HW=42.03' TW=40.23' (Dynamic Tailwater) 1=Culvert (Inlet Controls 1.4 cfs @ 2.3 fps) Summary for Pond CB7: Inflow Area = 10,201 sf, 83.19% Impervious, Inflow Depth > 3.41" for 10-YR event Inflow = 0.9 cfs @ 12.10 hrs, Volume= 2,899 cf Outflow = 0.9 cfs @ 12.10 hrs, Volume= 2,899 cf, Atten= 0%, Lag= 0.0 min Primary = 0.9 cfs @ 12.10 hrs, Volume= 2,899 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 41.54' @ 12.94 hrs Flood Elev= 43.80' Device Routing Invert Outlet Devices #1 Primary 40.80'12.0" Round Culvert L= 41.0' CPP, projecting, no headwall, Ke= 0.9? Inlet / Outlet Invert= 40.80' / 40.60' S= 0.0049 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=0.9 cfs @ 12.10 hrs HW=41.39' TW=40.29' (Dynamic Tailwater) 1=Culvert (Barrel Controls 0.9 cfs @ 2.6 fps) Summary for Link A: LOT 48-62 WETLAND Inflow Area = 63,928 sf, 64.67% Impervious, Inflow Depth > 1.16" for 10-YR event Inflow = 1.5 cfs @ 12.16 hrs, Volume= 6,190 cf Primary = 1.5 cfs @ 12.16 hrs, Volume= 6,190 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Link B: MAIN ST ROW Inflow Area = 25,195 sf, 64.55% Impervious, Inflow Depth > 2.45" for 10-YR event Inflow = 1.3 cfs @ 12.15 hrs, Volume= 5,153 cf Primary = 1.3 cfs @ 12.15 hrs, Volume= 5,153 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Link C: LOT 48-60 Inflow Area = 2,194 sf, 0.00% Impervious, Inflow Depth > 0.07" for 10-YR event Inflow = 0.0 cfs @ 13.74 hrs, Volume= 13 cf Primary = 0.0 cfs @ 13.74 hrs, Volume= 13 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs 2296.00 DRAINAGE TEST PIT DATA LATHAM CENTERS 1439 MAIN STREET BREWSTER, MA 9/19/19 Test Pit #1 0-9” - 10YR 3/3 Dark Brown loamy sand, granular friable 9-33”- 10YR 5/6 Yellowish Brown loamy fine sand, single grain loose 33-120”- 2.5Y 6/6 Olive Yellow fine sand, single grain loose ESHWT = >120” Observed Water = None Ledge/Boulders = None Roots = 96” Est Perc >2 min/in 9/19/19 Test Pit #2 0-42” - 10YR 3/3 Dark Brown loamy sand, granular friable (sandy, loamy fill) 42-72”- 10YR 5/6 Yellowish Brown loamy fine sand, single grain loose (few boulders) ESHWT = >72 ” Observed Water = None Ledge/Boulders = None Roots = 72” Est Perc >2 min/in 9/19/19 Test Pit #3 0-8” - 10YR 3/3 Dark Brown loamy sand, granular friable 8-40”- 10YR 5/6 Yellowish Brown loamy fine sand, granular friable (some compaction) 40-98”- 2.5Y 6/4 Light Yellowish Brown loamy fine sand, granular friable ESHWT = >98 ” Observed Water = None Ledge/Boulders = None Roots = 96” Est Perc >2 min/in Christopher A. Guida, CSS, CWS NH Septic Designer #1401 Massachusetts Soil Evaluator #13488 Latham Centers 1439 Main Street Brewster, MA 2296.00 Photo Page 1 of 3 PHOTO 1 DH-1 START OF EXCAVATION PHOTO 2 SANDY SOIL Latham Centers 1439 Main Street Brewster, MA 2296.00 Photo Page 2 of 3 PHOTO 3 TYPICAL DEEP HOLE PHOTO 4 PERC TESTING Latham Centers 1439 Main Street Brewster, MA 2296.00 Photo Page 3 of 3 PHOTO 5 SEPTIC AREA DEEP HOLES PHOTO 6 COMPLETED PRIMARY AND RESERVE SEPTIC AREAS Inspection & Maintenance Manual 31848.01 The Latham Center Operation & Maintenance Manual The Latham Center 1439 Main Street Brewster, MA 02631 December 11, 2019 Revised January 30, 2020 Revised June 26, 2023 Table of Contents Description of Project Responsible Party Stormwater Practices – Schedule of Maintenance Stormwater Practices – Maintenance Guidelines Treatment Practices Subsurface Chamber System (Chambers) Pretreatment Practices Subsurface Chamber System (Isolator Row) Control of Invasive Plants Inspection & Maintenance Log Inspection Checklist and Inspection & Maintenance Plan Inspection & Maintenance Manual 31848.01 The Latham Center Description of Project The property, located at 1439 Main Street, is formally the home of the New England Fire and History Museum and consists of several structures, gravel and paved access and parking areas and open space. Existing access to the site comes via a paved driveway off Main Street (1901 State Highway L.O. 545). The Latham Center is proposing to expand their current facility, located at 1646 Main Street, to serve at administrative office space and educational facility, including gym and auditorium. The redevelopment proposes removal of two outbuildings, renovation and construction of additions to the existing structures, reconstruction of the existing paved/gravel parking and access areas, improvements to the stormwater management system and upgrades to landscaping features throughout the site. Municipal water, g as and electric services, currently available on the site, will be extended. Septic and drainage improvements will be located on-site. Existing drainage paths will be maintained throughout the site. One subsurface infiltration system is proposed for stormwater management. A closed drainage system will convey stormwater runoff to the proposed system. Responsible Party Operator: Latham Center, Inc. Address: 1646 Main Street, Brewster, MA 02631 Contact: Anne McManus, President Phonte: (774) 353-9250 Email: amcmanus@lathamcenters.org In accordance with the Town of Brewster Stormwater Management Regulations Section 8.2.A., the Responsible Party shall ensure that all components of the Stormwater Management Plan are functioning according to manufacturer or design specifications for the life of the system. All components shall be maintained in good condition and promptly repaired, in accordance with the approved Operation and Maintenance Plan. Responsibility shall be conveyed to any future owners, heirs, or assigns. In accordance with the Town of Brewster Stormwater Management Regulations Section 8.3, this Operation and Maintenance Plan shall be recorded with the Barnstable County Registry of Deeds. In accordance with the Town of Brewster Stormwater Management Regulations Section 8.4.A., the Permittee shall keep records of all inspections, maintenance, and repairs and shall retain the records for at least five (5) years. These records shall be made available to the Stormwater Authority or Designated Agent during inspection of the stormwater management structure or system and at other reasonable times upon request. In accordance with the Town of Brewster Stormwater Management Regulations Section 8.5.B., The Stormwater Authority or Designated Agent may request written records documenting maintenance of the system, including receipts of inspection or cleaning services, and/or may physically inspect the systems to ensure that the proper maintenance has been carried out. Failure of the Permittee to maintain the stormwater management system in reasonable order and condition, in conformance with the approved Operation and Maintenance Plan, shall be Inspection & Maintenance Manual 31848.01 The Latham Center considered a violation of these Regulations and shall be subject to enforcement action in accordance with § 272-14 of the Stormwater Management Bylaw. In accordance with the Town of Brewster Stormwater Management Regulations Section 8.5., The Permittee shall notify the Stormwater Authority or Designated Agent of changes in ownership or assignment of financial responsibility for O&M of the stormwater management system or any changes to the Operation and Maintenance Plan within thirty (30) business days of the change. The Permittee shall also be responsible for informing prospective new owners of the requirements of the existing Operation and Maintenance Plan. Snow storage procedures and locations shall be in accordance with the MassDEP Snow Disposal Guidance, dated December 11, 2020, as amended. Snow shall not be stored or disposed of in any proposed stormwater BMP. Stormwater Practices – Schedule of Maintenance The following practices shall be inspected twice annually; once following snow-melt (spring) and once following leaf-drop (fall): • Subsurface Chamber System (Isolator Row) • Subsurface Chamber System (Chambers) The following practices shall be inspected annually following snow-melt (spring): • Riprap Apron • Conveyance Swale Stormwater Practices – Maintenance Guidelines Treatment Practices (Inspected twice a year) Subsurface Chamber System (Chambers) Maintenance Requirements: • The Chambers shall be inspected immediately after completion of the site construction and cleaned out if necessary. The typical inspection schedule after construction for the Chambers is a minimum of twice a year (spring & fall). • Inspection of the Chambers shall involve a visual check using the access manholes. • If upon visual inspection of the Chambers, it is found that sediment has accumulated to an average depth exceeding 3 inches throughout the length of the Chambers, cleanout is required. • Cleanout of the accumulated material in the Chambers should be accomplished by vacuum pumping. • If the system does not drain within 72-hours following a rainfall event, then a qualified professional should assess the condition of the facility to determine measures required to restore function, including but not limited to removal of accumulated sediments or reconstruction of the system. • A site maintenance log will be kept. This log will record the dates when maintenance tasks were completed, the person who completed the task, and any observations of malfunctions in components of the stormwater management system. Call 1-888-892-2694 to speak with a Technical representative or visit www.stormtech.com. • Remove and dispose of accumulated sediment based on inspection. Inspection & Maintenance Manual 31848.01 The Latham Center Pretreatment Practices (Inspected twice a year) Subsurface Chamber System (Isolator Rows) Maintenance Requirements: • Isolator Rows shall be inspected immediately after completion of the site construction and cleaned out if necessary. The typical inspection schedule after construction for the Isolator Rows is a minimum of twice a year (spring & fall). • Inspection of the Isolator Row shall involve a visual check using either the inspection ports or the access manholes. • If upon visual inspection of the Isolator Row, it is found that sediment has accumulated to an average depth exceeding 3 inches throughout the length of the Isolator Row, cleanout is required. • Cleanout of the accumulated material in the Isolator Row should be accomplished by vacuum pumping. Cleanout should be performed during dry weather and care should be taken to avoid tearing the fabric in the Isolator Rows. • A site maintenance log will be kept. This log will record the dates when maintenance tasks were completed, the person who completed the task, and any observations of malfunctions in components of the stormwater management system. Call 1-888-892-2694 to speak with a Technical representative or visit www.stormtech.com. Conveyance Practices (Inspected once a year) Riprap Apron Maintenance Requirements: • Inspect a least once annually for damage and deterioration. • Repair damages immediately. Control of Invasive Plans During maintenance activities, check for the presence of invasive plants. If invasive plants are found, they shall be controlled and remove in a safe manner as described on the following pages. Invasive plants are introduced, alien, or non-native plants, which have been moved by people from their native habitat to a new area. Some exotic plants are imported for human use such as landscaping, erosion control or food crops. They also can arrive as “hitchhikers” among shipments of other plants, seeds, packing materials or fresh produce. Invasive plants can cause harm by: • Becoming weedy and overgrown; • Killing established shade trees; • Obstructing pipes and drainage systems • Forming dense beds in water • Lowering water levels in lakes, streams and wetlands • Destroying natural communities • Promoting erosion on stream banks and hillsides • Resisting control except by hazardous chemicals. Inspection & Maintenance Manual 31848.01 The Latham Center Inspection & Maintenance Log Date Inspector BMPs Inspected Maintenance Required *Inspection & Maintenance Records to be provided to MassDEP and/or the Town of Brewster upon request. Inspection & Maintenance Manual 31848.01 The Latham Center Inspection Checklist Date: Project Name: The Latham Center Inspector’s Name/Title: Inspector’s Contact Information:  1st Yearly Inspection  2nd Yearly Inspection BMP’s to be inspected: All BMP’s to be inspected: Treatment and Pretreatment Practices BMP* Refer to following Inspection & Maintenance Plan for BMP location Maintenance Required Corrective Action Needed and Notes 1 StormTech System  Yes  No 2 CB 1  Yes  No 3 CB 2  Yes  No 4 CB 3  Yes  No 5 CB 4  Yes  No 6 CB 5  Yes  No 7 Concrete Headwall  Yes  No 8 Headwall Rip-Rap Outlet  Yes  No 9 CB 7  Yes  No *Best Management Practices – see Operation & Maintenance Plan for locations. **Photographs of BMPs shall be included as part of the required Inspections ***Copies of Inspection & Maintenance Records shall be provided to the City of Manchester upon request © Potential Snow Storage Area A A C B 1S 2S 3S 4S 5S 6S ER-1 © J a n 2 9 , 2 0 2 0 - 4 : 5 7 p m F: \ T F M P r o j e c t s \ 3 1 8 4 8 L a t h a m C e n t e r - B r e w s t e r , M A \ 3 1 8 4 8 - 0 1 L a t h a m C t r C i v i l & L a n d s c a p e S e r v i c e s \ 3 1 8 4 8 - 0 1 _ C 3 D \ P R O D U C T I O N \ 3 1 8 4 8 - 0 1 D R A I N A G E . d w g POI-1 ES-1 EP-1 ER-1 SOIL LEGEND (PER USDA NRCS WEB SOIL SURVEY) SYMBOL DESCRIPTION HYDROLOGIC SOIL GROUP DRAINAGE CLASS A A C B 1S 2S 3S 4S 5S 7S 8S 9S 10S 11S 12S 6S ER-1 © SOIL LEGEND (PER USDA NRCS WEB SOIL SURVEY) SYMBOL DESCRIPTION HYDROLOGIC SOIL GROUP DRAINAGE CLASS POI-1 PS-1 PP-1 PR-1 CONTINUED REVIEW AND DISCUSSION ON ADU PROVISIONS INCLUDING POTENTIAL AMENDMENTS APPROVAL OF MEETING MINUTES DATED JULY 12, 2023 PB Minutes 07/12/23 Page 1 of 5 Brewster Planning Board 2198 Main Street Brewster, MA 02631-1898 (508) 896-3701 x1133 brewplan@brewster-ma.gov MEETING MINUTES Wednesday, July 12, 2023 at 6:30 pm Brewster Town Office Building Chair Amanda Bebrin convened a meeting of the Planning Board at 6:30 pm with the following members participating: Charlotte Degen, Tony Freitas, Rob Michaels, Elizabeth Taylor, and Alex Wentworth. Madalyn Hillis-Dineen was not present. Also participating: Jon Idman, Town Planner, and Lynn St. Cyr, Senior Department Assistant. Bebrin declared that a quorum of the Planning Board was present. She read the Meeting Participation Statement and Recording Statement. 6:32 PM PUBLIC ANNOUNCEMENTS AND COMMENT No citizen comments. 6:33 PM PUBLIC MEETING Major Stormwater Management Permit, Case No. 2023-26: Applicant/Owner: Bridget E. Cahill through her representative JM O’Reilly & Associates, Inc. has submitted a major stormwater permit application for property located at 500 Run Hill Road and shown on Tax Map 33, Parcel 40, pursuant to Brewster Town Code Chapter 272 and its accompanying Regulations. Documents:  06/12/23 Existing Conditions Plan  06/12/23proposed Site & Drainage Plan  06/13/23 Stormwater Management Permit Application  06/13/23 Stormwater Management Report and Operations & Maintenance Manual, revised 07/03/23  07/05/23 Staff Report John O’Reilly P.E., P.L.S. of JM O’Reilly & Associates, Inc. was present on behalf of the Applicant Bridget E. Cahill. O’Reilly stated that a major stormwater permit has been prepared which takes advantage of the natural topography of the lot. He noted the natural depression at the front of the property to the east of the dwelling. O’Reilly stated that renovations to the home will double the size of the dwelling. He stated that roof runoff will be collected through a series of gutters, downspouts and an ADS pipe which discharges just west of the depression. O’Reilly stated that he has provided volume calculations and believes the application is compliant with the Stormwater Regulations. Wentworth appreciated the use of the natural depression on the property. Wentworth asked about required maintenance for the proposed splash pad. O’Reilly responded that the rip rap will be cleared of debris and leaf litter. The driveway will be cleaned and gutters maintained. Michaels also appreciated the use of the natural depression. He asked whether runoff could exceed the 46’ contour and flood the road. O’Reilly directed Michaels to volume calculations provided and noted that 75-80,000 gallons of water was accounted for up to the 46’ contour. O’Reilly stated that he did not foresee a storm that would generate enough water to overflow and flood the road. Bebrin asked for clarification on waivers for nitrogen and phosphorus. O’Reilly stated that using a natural depression is different from creating a bio swale or drain. He does not think a waiver is necessary. Idman stated that it is his opinion that a waiver is not needed. He stated that there are a few different ways that the treatment requirement could be met for total phosphorous and TSS. Idman stated that O’Reilly showed through his volume calculations that treatment requirements can be met. Idman further stated that going forward the Planning Board should consider addressing, through their Approved: Vote: PB Minutes 07/12/23 Page 2 of 5 regulations, how to encourage the use of natural features and low impact development. Idman also noted that the portion of the property on Run Hill Road is on the private section not the public section of Run Hill Road. Motion by Wentworth to Approve Major Stormwater Management Permit, Case No. 2023-26, subject to the Conditions Required by the Stormwater Management Regulations. Second by Taylor. Vote: 6-0-0. 6:40 PM PUBLIC MEETING Approval Not Required, Case No. 2023-06: Applicant/Owner: Eastward Companies Business Trust through their representative JM O’Reilly & Associates, Inc. seeks endorsement of an Approval Not Required Plan for property located on Main Street and shown on Tax Map 138, Parcels 74, 75, 76, 77, 78, 79, 80, and 81 within the Village Business (V-B) Zoning District. The plan is pursuant to MGL c. 41 §81L and §81P and §290-4 of the Brewster Subdivision Rules and Regulations. Documents:  07/05/23 Approval Not Required Application and Plan  07/05/23 Staff Report John O’Reilly P.E., P.L.S. of JM O’Reilly & Associates, Inc. was present on behalf of the Applicant Eastward Companies Business Trust. Susan Ladue of Eastward Companies participated remotely. Wentworth recused himself from the meeting as he is an abutter to the subject property. O’Reilly stated that the parcel is made up of eight lots on the corner of Route 6A and Vesper Pond Drive across the street from the Haven Center and adjacent to the Brewster/Orleans office park. O’Reilly stated that three lots are being created from the eight lots and are intended for residential homes. He stated that all the lots are compliant with area and frontage. Access to Lot A will be via Vesper Pond Drive. Lots B and C will be served by a driveway easement with one curb cut to Route 6A. The previous plan of eight lots included dual driveway easements. Degen asked O’Reilly if he was confident that access was available through Vesper Pond Drive given that it is a private road. O’Reilly responded that the owners of the western lot do have access and frontage on Vesper Pond Drive. Freitas noted that the lots are in the Village Business (V-B) zoning district and asked if the approval not required (ANR) plan would change that designation. Idman stated that single-family dwellings are allowed in the V-B district. He further stated that zoning compliance is not reviewed as part of the ANR process, but it does appear that the project complies with zoning. Idman further stated that he is confident that the Applicant has rights in Vesper Pond Drive. Bebrin stated that she is satisfied the requirements for an ANR plan have been met. Motion by Degen to Endorse Approval Not Required, Case No. 2023-06. Second by Michaels. Vote: 5-0-0. 6:50 PM PLANNING DISCUSSION Discussion with Brewster Historical Commission regarding a potential demolition delay bylaw. Documents:  07/07/23 Memorandum from Brewster Historical Commission Patricia Hess, a member of the Brewster Historical Commission (BHC), stated that the Historical Commission has been discussing a demolition delay bylaw for at least the last 10 years. BHC has never really taken a stand for or against a demolition delay bylaw. A demolition delay bylaw can only delay not stop a demolition. In her work with staff on the Local Comprehensive Plan (LCP), demolition delay was raised during the conversation on community character, so the BHC decided to do more research as to whether a demolition delay bylaw was needed. Hess directed the Planning Board to a map she provided for their meeting packet. She pointed out the Old King’s Highway (OKH) and noted the houses in green in the OKH historic district. She stated that OKH historic district does not necessarily cover all houses on a road. Houses located out towards the beach are not all covered. She pointed out PB Minutes 07/12/23 Page 3 of 5 houses shown in red on the map which are not covered by the OKH historic district. Hess stated that Brewster lost half its population between 1870 and 1910 so no new residential buildings were being constructed. The development of the automobile became a factor in Brewster becoming a summer tourist community as did the development of Brewster Park as well as cottages on Swift Lane, cottages near Pineland Park, and cottages on Ellis Landing. Hess stated that there are very few houses outside of OKH historic district that would be covered by a demolition delay bylaw. She stated that the OKH Historic District Committee (OKH HDC) is local and regional and has rules and regulations that would not allow the town to impose a demolition delay bylaw in their jurisdiction. Hess stated that the OKH HDC can stop demolition but cannot agree to a delay. A demolition delay bylaw would ask an applicant to agree to delay demolition for a certain period of time. During the delay period, discussions could happen with the owner to see if there was interest in preservation. Hess stated that the BHC has decided as a commission they are not in favor of a demolition delay bylaw because the OKH historic district covers 317 of the houses identified as historic in Brewster and many of the houses that are not covered are cottages many of which have been changed. She asked the Planning Board for their thoughts on a demolition delay bylaw. She noted the concern of the BHC that a demolition delay bylaw would be another layer of regulations. She stated that of the 50 houses outside the OKH historic district, only 10 were built before 1900. After 1900, as residential building resumed, most were bungalows and cottages. The BHC wondered if it was worth going through the bylaw process to save the cottages and bungalows. Taylor stated that there are several towns along Route 6A that have historic districts and demolition delay bylaws. She wondered if an overlay district would allow for demolition delay. Idman asked how the BHC defined historic houses. Hess responded that in 2016 the BHC commissioned a survey of all the historic properties in Brewster. The BHC worked with a consultant to review houses built before 1925. Each of those houses now has a Form B or historic narrative which can be found in the Brewster Ladies Library. Idman stated that a demolition delay bylaw can overlap with a historic district but it can lead to awkward decision making. The better practice is to defer to the HDC who may prohibit demolition. Idman stated that if demolition delay is something the town wants another option may be to extend the historic district through special legislation. A historic district act can create design standards. Freitas asked if the purpose of the delay bylaw was to extend the historic district to the bay. Idman responded that the delay bylaw was a separate option. Freitas asked if most houses shown on the map provided for Brewster Park have been changed from their original construction. Hess responded that she believed that to be true in the context of Brewster Park originally being a family summer compound. Many of the houses in Brewster Park have been made into full-time houses. Hess also stated that several homes in the Ellis Landing cottage colony have been altered but there are still some original cottages. Freitas asked what the impact of the bylaw would be on the average person. Hess responded that the bylaw may allow a conversation with owners and lead to preservation of historical homes. Freitas asked Hess to confirm the definition of the historical designation. Hess stated that the BHC reviewed houses prior to 1925 as part of their survey. She stated that the town could decide what to designate as historic. She stated that some towns are moving towards historic designations for houses that are at least 75 years old. The survey was started to create an inventory of historical houses not for purposes of a demolition delay bylaw. Taylor stated that originally the OKH historic district went down to the bay. She asked why it was pulled back. Idman responded that it could be because its what residents wanted at the time. Taylor stated that extending the district may be the best option for historic preservation. Taylor asked Idman if he had suggestions for other options. Idman responded that the town may want to look to extend the historic district. Taylor asked whether the town should consider a bayside and seaside historic district. Hess responded that the BHC did consider such districts but wondered if it was worth it because most of the properties are cottages. Idman stated that there is a lot of baseline work to establish a local historic district. Idman stated that there are no design standards in zoning. PB Minutes 07/12/23 Page 4 of 5 Michaels stated that even if the demolition delay bylaw is not the best option it does send a message that Brewster cares about older homes. Michaels stated that he believes the historic district should be more inclusive. He stated that there are benefits to a demolition delay bylaw including conversations with owners. In response, Hess responded that houses shown in red were identified through the assessor’s database and BHC did additional research, so she is confident in their accuracy. Hess also stated that there are several areas of land in Brewster that are under conservation restriction so no homes can be built in those areas. Degen asked what would be involved in creating design standards. Idman responded that the best way to establish design standards would be to include them in the zoning bylaw. Considerations would have to include how broad the standards should be applied such as to every alteration or to focus on certain areas to apply design standards. Another consideration would be whether the standards would apply to both old and new buildings. The purpose of design standards is not to preserve the old bones of the property but more for aesthetics. Idman stated that a consultant would have to be hired to draft the design standards. Zoning would have to be changed to include reference to the design standards. Idman stated that the work would include assistance from a consultant, a regulatory process, and approval by Brewster residents. Degen asked whether design standards would help accomplish the goal of the BHC. Hess responded that it is not in the purview of the BHC but may sit with the OKH HDC. Hess stated that the role of the BHC is to look at the bigger picture and help with preservation. Hess stated that the BHC would need to discuss whether design standards, in their opinion, would help preserve the character of the community. Hess felt that design standards should not be imposed on cottages. Idman stated that design standards are not necessarily for historic preservation but are more to maintain character in a certain area. The standards may include design related to roof lines to maintain views. Wentworth agreed that he would like to keep the smaller home character of the town but does not believe the demolition delay bylaw does that. Wentworth asked if design requirements could restrict the size of homes. Idman stated that floor area or height restrictions are possible. Wentworth stated that size needs to be restricted more than design. He believes enormous homes are changing the character of Brewster. He would prefer to see a smaller modern home. Bebrin thanked Hess for her presentation. She stated that a demolition delay bylaw seems to be a lot of work for not a lot of return and it would be a hard sell at town meeting. Hess stated that this will be an ongoing conversation and she will be speaking to the OKH HDC next month. Jillian Douglass stated that Brewster was seeing a huge economic change that cannot be solved with zoning or regulations. An attempt at preserving the town’s character can be made with design standards. Douglass directed the Planning Board to the red dots on the map and noted how scattered they were and the challenge that would come with trying to preserve. Douglass also stated that a demolition delay bylaw does allow for engagement with abutters. She stated that the design standards should not just focus on the age of the construction. She does not think a delay bylaw is the answer, but it could be considered as a tool. 7:36 PM APPROVAL OF MEETING MINUTES Approval of Meeting Minutes: June 28, 2023. The Board reviewed the June 28, 2023 meeting minutes. Motion by Degen to Approve June 28, 2023 Meeting Minutes, as amended. Second by Freitas. Vote: 6-0-0. 7:37 PM COMMITTEE REPORTS Taylor stated that the Community Preservation Committee is reviewing new applications for the Fall Town Meeting. The Open Space Committee has received approval to have appraisals done on parcels for possible consideration at the Spring Town Meeting. PB Minutes 07/12/23 Page 5 of 5 Degen summarized a recent Select Board meeting. In August, a multigroup discussion will take place on local preference standards for the Millstone Road housing development. Over 1100 people participated in Brewster Conservation Day. The Select Board meeting also included a dangerous dog hearing. Wentworth stated that the Vision Planning Committee had a booth at Brewster Conservation Day and engaged with many residents and nonresidents regarding the Local Comprehensive Plan. Freitas attended his first meeting of the Affordable Housing Trust. The meeting was spent discussing the Millstone Road housing development and a letter in support of funding for the development. There was information provided at the meeting on new income levels and how they relate to providing rental assistance. Bebrin stated that the Bay Property Planning Committee met to review initial design concepts received from the consultant. A second public forum will take place on Saturday, August 5, 2023 from 1 pm- 4 pm in the dining hall. Some of the buildings will be open for public viewing. 7:42 PM FOR YOUR INFORMATION The Planning Board received a public hearing notice from the Harwich Planning Board for Tuesday, July 25, 2023. The Planning Board received an email from Talitha Abramsen of the CDP ADU Resource Center regarding Crested Butte, CO ADU bylaws. A copy of the presentation from the ADU Listening Session on June 28, 2023 was provided to the Planning Board. Idman stated that based on conversation and public input from the last meeting, he would like to present the Planning Board with a first draft of the ADU provisions at the next Planning Board meeting. DPW Director Griffin Ryder is expected to provide a stormwater management presentation to the Planning Board in the Fall. 7:44 PM MATTERS NOT REASONABLY ANTICIPATED BY THE CHAIR None. Motion by Wentworth to Adjourn. Second by Michaels. Vote: Vote: 6-0-0. The meeting adjourned at 7:45 PM. Next Planning Board Meeting Date: July 26, 2023. Respectfully submitted, __________________________________________ Lynn St. Cyr, Senior Department Assistant, Planning FOR YOUR INFORMATION