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HomeMy Public PortalAboutPlanning Board Packet 06/14/23MAJOR STORMWATER MANAGEMENT PERMIT CASE NO. 2023-09 APPLICANT/OWNER: KAREN AND DAVID WHITNEY PROPERTY: 25 SUMNER LANE 25 Sumner Lane SWMP23-9 Staff Report Page 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 SWMP23-9 25 Sumner Lane (Map 51 Parcel 65) Applicant, David & Karen Whitney c/o Brian Yergatian, PE, BSC Group, Inc. DATE: May 22, 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 a new paved driveway and detached residential accessory building on a previously developed lot. The property is located in the DCPC overlay district/ Zone II. It is not located in a flood zone, and is not affected by wetlands. Major Stormwater Permits are subject to review at a public meeting, including for any waivers requested. This project triggers a Stormwater Permit under Chapter 272 of the Brewster Code (Stormwater Management Bylaw) and according to Section 4 of the Bylaw’s supporting regulations, a Major Stormwater Permit is required because the project involves net new impervious surface of 2500 sq ft or greater. The Planning Board is the Stormwater Permitting Authority because the proposed development is located outside wetlands jurisdiction. The Applicant has provided the required application materials for a Major Stormwater Permit, including a site plan set (dated May 4, 2023) and Stormwater Management Report with HydroCad analysis (revised dated 5/15/23), as set out in Appendix B of the Stormwater Management Regulations. No waivers from the Bylaw/ Regulations have been requested or identified as necessary. The Stormwater Management approach meets the applicable standards in relevant Sections 6.1B and 6.2B of Brewster’s Stormwater Regulations, including consistency with the State Stormwater Handbook standards:  Stormwater from the new impervious surfaces will be directed to the existing natural depression in the southwest portion of the site for treatment and infiltration, as shown on the site plan.  The system was designed under post-development conditions to maintain stormwater recharge capacity on-site for the 2, 10, 25 and 100-year storm events;  As designed, post-development runoff rates are reduced to less than the pre-development conditions including for the 100-year storm; Office of: Planning Board Planning Dept. 25 Sumner Lane SWMP23-9 Staff Report Page 2  The Applicant has provided an Operations and Maintenance Manual that sets out proper, long- term procedures to maintain the proposed post-construction BMP;  The Applicant has provided an appropriate construction-period erosion and sedimentation control plan;  The site stormwater approach incorporates Low Impact Development-type (LID) stormwater design elements;  The site system provides the required TSS and Phosphorus treatment, including through “first flush” water quality volume retention;  The Applicant’s soil tests on the property, and NRCS mapping, have revealed sandy and well- draining soils.  There is sufficient vertical separation between the stormwater facilities and groundwater to allow proper system function. Stormwater Narrative 25 Sumner Lane Brewster, MA TABLE OF CONTENTS 1.0 PROJECT INFORMATION 1.01 PROJECT DESCRIPTION 1.02 PRE-DEVELOPMENT CONDITIONS 1.03 POST-DEVELOPMENT CONDITIONS 2.0 DRAINAGE SUMMARY 2.01 STORMWATER STANDARD 1 – NEW STORMWATER CONVEYANCES 2.02 STORMWATER STANDARD 2 – STORMWATER RUNOFF RATES 2.03 STORMWATER STANDARD 3 – GROUNDWATER RECHARGE 2.04 STORMWATER STANDARD 4 – TSS REMOVAL 2.05 STORMWATER STANDARD 5 – LUHPPL 2.06 STORMWATER STANDARD 6 – CRITICAL AREAS 2.07 STORMWATER STANDARD 7 – REDEVELOPMENT PROJECTS 2.08 STORMWATER STANDARD 8 – SEDIMENTATION & EROSION CONTROL PLAN 2.09 STORMWATER STANDARD 9 – LONG TERM O&M PLAN 2.10 STORMWATER STANDARD 10 – ILLICIT DISCHARGES 2.11 CONCLUSIONS 3.0 LONG-TERM POLLUTION PREVENTION & OPERATION AND MAINTENANCE PLAN 4.0 ILLICIT DISCHARGE COMPLIANCE STATEMENT 5.0 HYDROLOGY CALCULATIONS 5.01 EXISTING WATERSHED PLAN 5.02 EXISTING HYDROLOGY CALCULATIONS (HYDROCAD™ PRINTOUTS) 5.03 PROPOSED WATERSHED PLAN 5.04 PROPOSED HYDROLOGY CALCULATIONS (HYDROCAD™ PRINTOUTS) 6.0 ADDITIONAL DRAINAGE CALCULATIONS 6.01 WATER QUALITY VOLUME CALCULATION APPENDICES APPENDIX A – USGS LOCUS MAP APPENDIX B – FEMA MAP APPENDIX C – WEB SOIL SURVEY APPENDIX D – MASSDEP STORMWATER CHECKLIST Stormwater Narrative 25 Sumner Lane Brewster, MA SECTION 1.0 PROJECT INFORMATION Stormwater Narrative 25 Sumner Lane Brewster, MA 1.01 PROJECT DESCRIPTION The project, located at 25 Sumner Lane Brewster, MA, consists of the construction of a proposed garage and driveway. The existing garage will be converted into a guest house, with the addition of a septic system. Additional site work includes modifications to the limits of the existing driveway, modifications to site utilities that are obstructed by the proposed addition, site drainage, and temporary erosion control features. The anticipated land disturbance is approximately 20,275± S.F. with a net increase of 3,650± S.F. of impervious area. Based on these figures, this project meets the criteria for a M ajor Stormwater Permit with the Town of Brewster. 1.02 PRE-DEVELOPMENT CONDITIONS The existing site on 51,208± S.F. of land consists of a three-bedroom dwelling, a garage, driveway, and a combination of grass/wooded areas. In the current conditions there is 6,048± S.F. of impervious area. There are currently not any stormwater management facilities on-site, and as such stormwater infiltrates on- site or eventually flows off-site generally in a northwest to northeast direction. The site has a very gentle slope, 0-3% and this allows for stormwater to have a longer time of concentration path, which increases the amount of natural infiltration on site. On the northwest side of the property, there is a natural basin, where the water tends to go to. The northeast side seems to continue going off site. Furthermore, most of the site is pervious, consisting of grass and wooded areas which contain various sized low spots along the southeast property line which supports infiltration on-site. There are no current issues on the site regarding off-site stormwater flows. There is one primary soil classification identified by the NRCS Web Soil Survey. It is Carver coarse sand (252D), which is classified by NRCS as Hydraulic Soil Group (HSG) A. 1.03 POST-DEVELOPMENT CONDITIONS The proposed conditions include four improvements/additions to the existing dwelling. Additionally, there are proposed modification to the existing driveway and site utilities. There is 9,808± S.F. of impervious area in the proposed conditions which results in a net increase of 3,650± S.F. Based on the site improvements and limit of work line, the site disturbance is expected to be 20,275± S.F. Due to the limited amount of site work associated with this project, the post -development drainage patterns remain similar to the pre-development conditions. In compliance with the Town of Brewster Stormwater Regulations, a BMP based on LID design principles, a natural infiltration basin, has been implemented. Proposed grading on the site will maintain this existing natural basin south of the proposed driveway, catching all runoff on the west of the property. The building additions will increase the amount of stormwater, however no part of the building additions are any closer to the low lying areas that serve as the low-point on the site. Stormwater will continue to travel over grass and wooded areas and infiltrate on-site. Based on these proposed changes, the site will see an increase in stormwater infiltrated on-site and a reduction in off-site flow. Temporary erosion control measures will serve to minimize construction-associated impacts to undisturbed areas. Temporary erosion control measures for this project include siltsoxx compost filter sock, dewatering basin, and material stockpile area. Stormwater Narrative 25 Sumner Lane Brewster, MA Siltsoxx, Haybales, and/or Silt Fencing The siltation barriers will demarcate the limit of work, form a work envelope and provide additional assurance that construction equipment will not enter the adjacent wetlands or undisturbed portions of the site. All barriers will remain in place until disturbed areas are stabilized. Material Stockpiling Locations Piping and trench excavate associated with the subsurface utility work will be contained with a single row of silt socks and/or haybales. Dewatering Basins Dewatering may be required during stormwater system, foundation construction and utility install ation. Should the need for dewatering arise, groundwater will be pumped directly into a temporary settling basin, which will act as a sediment trap during construction. All temporary settling basins will be located within close proximity of daily work activities. Prior to discharge, all groundwater will be treated by means of the settling basin or acceptable substitute. Discharges from sediment basins will be free of visible floating, suspended and settleable solids that would impair the functions of a wetland or degrade the chemical composition of the wetland resource area receiving ground or surface water flows and will be to the combined system. Stormwater Narrative 25 Sumner Lane Brewster, MA Stormwater Narrative 25 Sumner Lane Brewster, MA SECTION 2.0 DRAINAGE SUMMARY Stormwater Narrative 25 Sumner Lane Brewster, MA 2.01 Stormwater Standard 1 – New Stormwater Conveyances Per Stormwater Standard 1, no new outfalls may discharge untreated stormwater directly to or cause erosion in wetlands or waters of the Commonwealth. No new untreated stormwater discharges are proposed. Any stormwater to the west of the property will be infiltrated into the improved natural basin. There will be an increase of 3,650± S.F. of impervious area. 2.02 Stormwater Standard 2 – Stormwater Runoff Rates Watershed modeling was performed using HydroCAD Stormwater Modeling Software version 10.00, a computer aided design program that combines SCS runoff methodology with standard hydraulic calculations. A model of the site’s hydrology was developed for both pre- and post-development conditions to assess the effects of the proposed development on the project site and surrounding areas. The stormwater management system for the project has been designed such that the post-development conditions result in no increase to peak runoff rates off the project site for the 2, 10, and 100-year, 24-hour storm events, as detailed in the tables below. Peak Flow Discharge Rates Table 1.1 – Peak Flow Rates Summary to West (209P) Storm Event Pre-Development Peak Discharge Rate (cfs) Post-Development Peak Discharge Rate (cfs) Change in Peak Discharge Rate (cfs) 2-Year 0.0 0.0 0.0 10-Year 0.0 0.0 0.0 100-Year 0.2 0.0 -0.2 Table 1.2 – Peak Flow Rates Summary to East (200P) Storm Event Pre-Development Peak Discharge Rate (cfs) Post-Development Peak Discharge Rate (cfs) Change in Peak Discharge Rate (cfs) 2-Year 0.0 0.0 0.00 10-Year 0.2 0.2 0.00 100-Year 0.8 0.8 0.00 As demonstrated in the tables above, the project meets the requirements of Stormwater Standard 2. 2.03 Stormwater Standard 3 – Groundwater Recharge The required recharge volume is estimated based on the Massachusetts Stormwater Management Standards #3, and the proposed stormwater management system is designed to meet this standard to the maximum extent practicable. Infiltration BMP, a natural infiltration basin is proposed throughout the site. Overall, this project is designed to route as much runoff as practicable to the infiltration BMP to further increase groundwater recharge. While the project meets the overall requirements of Standard 3, specific infiltration BMP’s have been designed in accordance with the Stormwater Narrative 25 Sumner Lane Brewster, MA requirements of the Stormwater Handbook to the maximum extent practicable based on existing site conditions and project goals. 2.04 Stormwater Standard 4 – TSS Removal The Project complies with the Town of Brewster TSS removal regulation, “Stormwater management systems for redevelopment shall be designed to remove, at a minimum, 80% of the average annual load of TSS and 50% of the average annual load of TP generated from the total pos-construction impervious area on site”. All runoff generated from the proposed impervious area, up to and including the 100-year storm, will be retained on site in the natural basin with 15 feet of freeboard. 2.05 Stormwater Standard 5 – Land Uses with Higher Potential Pollutant Loads The Project does not qualify as a land use with higher potential pollutant loads (LUHPPL) because it generates less than 1,000 trips per day. 2.06 Stormwater Standard 6 – Stormwater Discharges to a Critical Area The Project property is not located within or near any critical areas. 2.07 Stormwater Standard 7 – Redevelopment Projects This project qualifies as a redevelopment project under Stormwater Standard 7. However, the project has been designed to fully comply with all Stormwater Standards. 2.08 Stormwater Standard 8 – Sedimentation and Erosion Control Plan Erosion and sedimentation controls are shown on the Project Plans. Additionally, a Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan is included in the submitted plan set. 2.09 Stormwater Standard 9 – Long Term Operation and Maintenance Plan A Long-Term Operation and Maintenance Plan is included in Section 3.0 of this Report. 2.10 Stormwater Standard 10 – Illicit Discharges There are no known illicit discharges on the project site, and none are proposed. An illicit discharge compliance statement is included in Section 4.0 and will be signed by the Applicant prior to issuance of any permits. 2.11 Conclusion As a new development project, this has been designed in accordance with DEP Stormwater Management Standards and the Town of Brewster Stormwater Management Regulations. There will be an approximate 3,650± S.F. increase of impervious area. Through the construction of the proposed infiltration BMP’s that have been designed based on LID principles, the project will provide peak rate attenuation and groundwater recharge. The BMP has also been designed to remove 100% of the average annual load of Total Suspended Solids (TSS) and 60% of the average annual load of Total Phosphorus (TP) generated from the total post-construction impervious surface are on the site. This has been achieved through retaining the volume of runoff greater than 0.8 inch multiplied by the total post-construction impervious area on the site. Stormwater Narrative 25 Sumner Lane Brewster, MA SECTION 3.0 LONG-TERM POLLUTION PREVENTION & OPERATION AND MAINTENANCE PLAN Stormwater Narrative 25 Sumner Lane Brewster, MA 2.0 LONG-TERM POLLUTION PREVENTION & OPERATION AND MAINTENANCE PLAN REQUIREMENTS FOR ROUTINE INSPECTIONS AND MAINTENANCE OF STORMWATER BMPS All stormwater BMPs are to be inspected and maintain as follow Siltsoxx, Haybales, and/or Silt Fencing The temporary erosion control measures will be installed up gradient of any wetland resource area where any disturbance or alteration might otherwise allow for erosion or sedimentation. They will be regularly inspected to ensure that they are functioning adequately. Additional supplies of these temporary measures will be stockpiled on site for any immediate needs or routine replacement. Infiltration Basin Frequent maintenance is essential because infiltration basins have high failure rates due to improper siting and lack of maintenance. Inspect to ensure proper functioning after every major storm during the first three months of operation and twice a year thereafter and when there are discharges through the high outlet orifice. Maintenance includes removing debris within the basin (e.g. leaves, branches, ect.) by hand or with a leaf blower. The grass in the depression shall not be mowed, allowing for natural vegetation growth. PROVISIONS FOR MAINTENANCE OF LAWNS, GARDENS AND OTHER LANDSCAPE AREAS All lawns, trees, and landscaped areas will be maintained in accordance with the Town of Brewster’s standard practices for residential areas. PROVISIONS FOR SOLID WASTE MANAGEMENT (SITE TRASH) Trash will be placed in trash receptacles and the Owner will make provisions for its regular and timely removal. TRAINING OF STAFF OR PERSONNEL INVOLVED WITH IMPLEMENTING LONG-TERM POLLUTION PREVENTION PLAN The Long-Term Pollution Prevention Plan is to be implemented by property owner of the site. Trained and, if required, licensed Professionals are to be hired by the owner as applicable to implement the Long -Term Pollution Prevention Plan. CONSTRUCTION PHASE INSPECTION SCHEDULE AND EVALUATION CHECKLIST Inspection Date Inspector BMP Inspected Inspection Frequency Requirements Comments Recommendation Follow-up Inspection Required (yes/no) Silt Soxx Weekly and After Major Storm Events 1. Refer to the Massachusetts Stormwater Handbook Volume Two: Stormwater Technical Handbook (February 2008) for recommendations regarding frequency for inspections and maintenance of specific BMP’s 2. Inspections to be conducted by a qualified professional such as an environmental scientist or civil engineer. 3. Limited or no use of sodium chloride salts, fertilizers or pesticides recommended. Stormwater Narrative 25 Sumner Lane Brewster, MA Other Notes: (Include deviations from Conservation Commission Order of Conditions, Planning Board Approval s and Approved Plans). POST CONSTRUCTION PHASE INSPECTION SCHEDULE AND EVALUATION CHECKLIST Inspection Date Inspector BMP Inspected Inspection Frequency Requirements Comments Recommendation Follow-up Inspection Required (yes/no) Infiltration Basin Twice a year and After Major Storm Events 1. Refer to the Massachusetts Stormwater Handbook Volume Two: Stormwater Technical Handbook (February 2008) for recommendations regarding frequency for inspections and maintenance of specifi c BMP’s 2. Inspections to be conducted by a qualified professional such as an environmental scientist or civil engineer. 3. Limited or no use of sodium chloride salts, fertilizers or pesticides recommended. Other Notes: (Include deviations from Conservation Commission Order of Conditions, Planning Board Approvals and Approved Plans). Stormwater Narrative 25 Sumner Lane Brewster, MA SECTION 4.0 ILLICIT DISCHARGE COMPLIANCE STATEMENT Stormwater Narrative 25 Sumner Lane Brewster, MA SECTION 5.0 HYDROLOGY CALCULATIONS Stormwater Narrative 25 Sumner Lane Brewster, MA 5.01 EXISTING WATERSHED PLAN 40' WIDE SUMNER LANE 51,204± S.F. LOT 10 40 ' W I D E LA K E S H O R E D R I V E G G G G G W W W W W W S S 2S 1S 349 Main Street - Route 28 West Yarmouth, Massachusetts 02673 508 778 8919 File: Dwg.: Scale: Job No.: Revised: Date: PREPARED FOR: 05/04/2023 DAVID & KAREN WHITNEY 25 SUMNER LANE BREWSTER, MASSACHUSETTS 02631 50726.00 1" = 30' 25 SUMNER LANE STORMWATER SUMNER LANE BREWSTER MASSACHUSETTS (BARNSTABLE COUNTY) MANAGEMENT IN C 2023 BSC Group, Inc. SCALE: FEET0153060 1" = 30' EXISTING WATERSHED MAY 4, 2023 Stormwater Narrative 25 Sumner Lane Brewster, MA 5.02 EXISTING HYDROLOGY CALCULATIONS (HYDROCAD™ PRINTOUTS) 1S Yard West 2S Yard East 100P West Total 200P East Total Routing Diagram for 2023-05-04 5072600-PRE Prepared by BSC Group, Printed 5/12/2023 HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Subcat Reach Pond Link EWAM 2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 2HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Rainfall Events Listing Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 2-year Type III 24-hr Default 24.00 1 3.50 2 2 10-year Type III 24-hr Default 24.00 1 4.85 2 3 25-year Type III 24-hr Default 24.00 1 5.75 2 4 100-year Type III 24-hr Default 24.00 1 7.10 2 EWAM 2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 3HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 0.490 39 >75% Grass cover, Good, HSG A (1S, 2S) 0.024 98 Driveway (2S) 0.014 98 Paved parking, HSG A (1S) 0.086 98 Roofs, HSG A (1S, 2S) 0.007 98 Unconnected pavement, HSG A (1S) 0.008 98 Walkways/Brick Patio (2S) 0.539 30 Woods, Good, HSG A (1S, 2S) 1.168 42 TOTAL AREA EWAM 2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 4HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Soil Listing (all nodes) Area (acres) Soil Group Subcatchment Numbers 1.136 HSG A 1S, 2S 0.000 HSG B 0.000 HSG C 0.000 HSG D 0.032 Other 2S 1.168 TOTAL AREA EWAM 2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 5HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Ground Covers (all nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.490 0.000 0.000 0.000 0.000 0.490 >75% Grass cover, Good 1S, 2S 0.000 0.000 0.000 0.000 0.024 0.024 Driveway 2S 0.014 0.000 0.000 0.000 0.000 0.014 Paved parking 1S 0.086 0.000 0.000 0.000 0.000 0.086 Roofs 1S, 2S 0.007 0.000 0.000 0.000 0.000 0.007 Unconnected pavement 1S 0.000 0.000 0.000 0.000 0.008 0.008 Walkways/Brick Patio 2S 0.539 0.000 0.000 0.000 0.000 0.539 Woods, Good 1S, 2S 1.136 0.000 0.000 0.000 0.032 1.168 TOTAL AREA EWAM Type III 24-hr 2-year Rainfall=3.50"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 6HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Yard West Runoff = 0.0 cfs @ 24.00 hrs, Volume= 0.000 af, Depth> 0.00" Routed to Pond 100P : West Total Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 2-year Rainfall=3.50" Area (sf) CN Description 597 98 Paved parking, HSG A 6,432 39 >75% Grass cover, Good, HSG A 21,248 30 Woods, Good, HSG A 1,294 98 Roofs, HSG A 308 98 Unconnected pavement, HSG A 29,879 37 Weighted Average 27,680 92.64% Pervious Area 2,199 7.36% Impervious Area 308 14.01% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 1S: Yard West Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 0 0 0 0 0 0 0 0 0 Type III 24-hr 2-year Rainfall=3.50" Runoff Area=29,879 sf Runoff Volume=0.000 af Runoff Depth>0.00" Tc=6.0 min CN=37 0.0 cfs EWAM Type III 24-hr 2-year Rainfall=3.50"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 7HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Yard East Runoff = 0.0 cfs @ 12.43 hrs, Volume= 0.007 af, Depth> 0.17" Routed to Pond 200P : East Total Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 2-year Rainfall=3.50" Area (sf) CN Description 14,923 39 >75% Grass cover, Good, HSG A 2,456 98 Roofs, HSG A * 1,048 98 Driveway 2,215 30 Woods, Good, HSG A * 346 98 Walkways/Brick Patio 20,988 49 Weighted Average 17,138 81.66% Pervious Area 3,850 18.34% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 2S: Yard East Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.023 0.022 0.021 0.02 0.019 0.018 0.017 0.016 0.015 0.014 0.013 0.012 0.011 0.01 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0 Type III 24-hr 2-year Rainfall=3.50" Runoff Area=20,988 sf Runoff Volume=0.007 af Runoff Depth>0.17" Tc=6.0 min CN=49 0.0 cfs EWAM Type III 24-hr 2-year Rainfall=3.50"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 8HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 100P: West Total Inflow Area = 0.686 ac, 7.36% Impervious, Inflow Depth > 0.00" for 2-year event Inflow = 0.0 cfs @ 24.00 hrs, Volume= 0.000 af Outflow = 0.0 cfs @ 24.00 hrs, Volume= 0.000 af, Atten= 2%, Lag= 0.0 min Discarded = 0.0 cfs @ 24.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 55.50' @ 24.00 hrs Surf.Area= 0.000 ac Storage= 0.000 af Plug-Flow detention time= 5.5 min calculated for 0.000 af (94% of inflow) Center-of-Mass det. time= 2.0 min ( 1,386.1 - 1,384.1 ) Volume Invert Avail.Storage Storage Description #1 55.50' 135,874.273 af Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (acres) (feet) (acre-feet) (acre-feet) (acres) 55.50 0.000 0.0 0.000 0.000 0.000 56.00 40.000 25.0 6.667 6.667 0.001 60.00 2,422.000 183.0 3,697.674 3,704.341 0.062 65.00 5,990.000 287.0 20,368.180 24,072.521 0.155 70.00 10,555.000 383.0 40,827.301 64,899.821 0.279 75.00 18,178.000 520.0 70,974.452 135,874.273 0.511 Device Routing Invert Outlet Devices #1 Discarded 55.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.0 cfs @ 24.00 hrs HW=55.50' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.0 cfs) EWAM Type III 24-hr 2-year Rainfall=3.50"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 9HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Pond 100P: West Total Inflow Discarded Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 0 0 0 0 0 0 0 0 0 Inflow Area=0.686 ac Peak Elev=55.50' Storage=0.000 af 0.0 cfs 0.0 cfs EWAM Type III 24-hr 2-year Rainfall=3.50"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 10HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 200P: East Total Inflow Area = 0.482 ac, 18.34% Impervious, Inflow Depth > 0.17" for 2-year event Inflow = 0.0 cfs @ 12.43 hrs, Volume= 0.007 af Primary = 0.0 cfs @ 12.43 hrs, Volume= 0.007 af, Atten= 0%, Lag= 0.0 min Routed to nonexistent node 201P Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Pond 200P: East Total Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.023 0.022 0.021 0.02 0.019 0.018 0.017 0.016 0.015 0.014 0.013 0.012 0.011 0.01 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0 Inflow Area=0.482 ac 0.0 cfs 0.0 cfs EWAM Type III 24-hr 10-year Rainfall=4.85"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 11HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Yard West Runoff = 0.0 cfs @ 14.78 hrs, Volume= 0.006 af, Depth> 0.11" Routed to Pond 100P : West Total Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 10-year Rainfall=4.85" Area (sf) CN Description 597 98 Paved parking, HSG A 6,432 39 >75% Grass cover, Good, HSG A 21,248 30 Woods, Good, HSG A 1,294 98 Roofs, HSG A 308 98 Unconnected pavement, HSG A 29,879 37 Weighted Average 27,680 92.64% Pervious Area 2,199 7.36% Impervious Area 308 14.01% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 1S: Yard West Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.011 0.011 0.01 0.01 0.009 0.009 0.008 0.008 0.007 0.007 0.006 0.006 0.005 0.005 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.001 0.000 0 Type III 24-hr 10-year Rainfall=4.85" Runoff Area=29,879 sf Runoff Volume=0.006 af Runoff Depth>0.11" Tc=6.0 min CN=37 0.0 cfs EWAM Type III 24-hr 10-year Rainfall=4.85"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 12HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Yard East Runoff = 0.2 cfs @ 12.13 hrs, Volume= 0.023 af, Depth> 0.58" Routed to Pond 200P : East Total Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 10-year Rainfall=4.85" Area (sf) CN Description 14,923 39 >75% Grass cover, Good, HSG A 2,456 98 Roofs, HSG A * 1,048 98 Driveway 2,215 30 Woods, Good, HSG A * 346 98 Walkways/Brick Patio 20,988 49 Weighted Average 17,138 81.66% Pervious Area 3,850 18.34% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 2S: Yard East Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type III 24-hr 10-year Rainfall=4.85" Runoff Area=20,988 sf Runoff Volume=0.023 af Runoff Depth>0.58" Tc=6.0 min CN=49 0.2 cfs EWAM Type III 24-hr 10-year Rainfall=4.85"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 13HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 100P: West Total Inflow Area = 0.686 ac, 7.36% Impervious, Inflow Depth > 0.11" for 10-year event Inflow = 0.0 cfs @ 14.78 hrs, Volume= 0.006 af Outflow = 0.0 cfs @ 14.87 hrs, Volume= 0.006 af, Atten= 0%, Lag= 5.3 min Discarded = 0.0 cfs @ 14.87 hrs, Volume= 0.006 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 55.50' @ 14.87 hrs Surf.Area= 0.000 ac Storage= 0.000 af Plug-Flow detention time= 5.6 min calculated for 0.006 af (99% of inflow) Center-of-Mass det. time= 3.6 min ( 1,060.5 - 1,056.8 ) Volume Invert Avail.Storage Storage Description #1 55.50' 135,874.273 af Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (acres) (feet) (acre-feet) (acre-feet) (acres) 55.50 0.000 0.0 0.000 0.000 0.000 56.00 40.000 25.0 6.667 6.667 0.001 60.00 2,422.000 183.0 3,697.674 3,704.341 0.062 65.00 5,990.000 287.0 20,368.180 24,072.521 0.155 70.00 10,555.000 383.0 40,827.301 64,899.821 0.279 75.00 18,178.000 520.0 70,974.452 135,874.273 0.511 Device Routing Invert Outlet Devices #1 Discarded 55.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.0 cfs @ 14.87 hrs HW=55.50' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.0 cfs) EWAM Type III 24-hr 10-year Rainfall=4.85"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 14HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Pond 100P: West Total Inflow Discarded Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.011 0.011 0.01 0.01 0.009 0.009 0.008 0.008 0.007 0.007 0.006 0.006 0.005 0.005 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.001 0.000 0 Inflow Area=0.686 ac Peak Elev=55.50' Storage=0.000 af 0.0 cfs 0.0 cfs EWAM Type III 24-hr 10-year Rainfall=4.85"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 15HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 200P: East Total Inflow Area = 0.482 ac, 18.34% Impervious, Inflow Depth > 0.58" for 10-year event Inflow = 0.2 cfs @ 12.13 hrs, Volume= 0.023 af Primary = 0.2 cfs @ 12.13 hrs, Volume= 0.023 af, Atten= 0%, Lag= 0.0 min Routed to nonexistent node 201P Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Pond 200P: East Total Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Inflow Area=0.482 ac 0.2 cfs 0.2 cfs EWAM Type III 24-hr 25-year Rainfall=5.75"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 16HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Yard West Runoff = 0.1 cfs @ 12.43 hrs, Volume= 0.016 af, Depth> 0.28" Routed to Pond 100P : West Total Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 25-year Rainfall=5.75" Area (sf) CN Description 597 98 Paved parking, HSG A 6,432 39 >75% Grass cover, Good, HSG A 21,248 30 Woods, Good, HSG A 1,294 98 Roofs, HSG A 308 98 Unconnected pavement, HSG A 29,879 37 Weighted Average 27,680 92.64% Pervious Area 2,199 7.36% Impervious Area 308 14.01% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 1S: Yard West Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Type III 24-hr 25-year Rainfall=5.75" Runoff Area=29,879 sf Runoff Volume=0.016 af Runoff Depth>0.28" Tc=6.0 min CN=37 0.1 cfs EWAM Type III 24-hr 25-year Rainfall=5.75"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 17HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Yard East Runoff = 0.4 cfs @ 12.11 hrs, Volume= 0.038 af, Depth> 0.95" Routed to Pond 200P : East Total Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 25-year Rainfall=5.75" Area (sf) CN Description 14,923 39 >75% Grass cover, Good, HSG A 2,456 98 Roofs, HSG A * 1,048 98 Driveway 2,215 30 Woods, Good, HSG A * 346 98 Walkways/Brick Patio 20,988 49 Weighted Average 17,138 81.66% Pervious Area 3,850 18.34% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 2S: Yard East Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.42 0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 25-year Rainfall=5.75" Runoff Area=20,988 sf Runoff Volume=0.038 af Runoff Depth>0.95" Tc=6.0 min CN=49 0.4 cfs EWAM Type III 24-hr 25-year Rainfall=5.75"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 18HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 100P: West Total Inflow Area = 0.686 ac, 7.36% Impervious, Inflow Depth > 0.28" for 25-year event Inflow = 0.1 cfs @ 12.43 hrs, Volume= 0.016 af Outflow = 0.0 cfs @ 12.52 hrs, Volume= 0.016 af, Atten= 12%, Lag= 5.4 min Discarded = 0.0 cfs @ 12.52 hrs, Volume= 0.016 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 55.50' @ 12.52 hrs Surf.Area= 0.000 ac Storage= 0.000 af Plug-Flow detention time= 5.6 min calculated for 0.016 af (100% of inflow) Center-of-Mass det. time= 4.0 min ( 994.8 - 990.9 ) Volume Invert Avail.Storage Storage Description #1 55.50' 135,874.273 af Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (acres) (feet) (acre-feet) (acre-feet) (acres) 55.50 0.000 0.0 0.000 0.000 0.000 56.00 40.000 25.0 6.667 6.667 0.001 60.00 2,422.000 183.0 3,697.674 3,704.341 0.062 65.00 5,990.000 287.0 20,368.180 24,072.521 0.155 70.00 10,555.000 383.0 40,827.301 64,899.821 0.279 75.00 18,178.000 520.0 70,974.452 135,874.273 0.511 Device Routing Invert Outlet Devices #1 Discarded 55.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.0 cfs @ 12.52 hrs HW=55.50' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.0 cfs) EWAM Type III 24-hr 25-year Rainfall=5.75"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 19HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Pond 100P: West Total Inflow Discarded Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Inflow Area=0.686 ac Peak Elev=55.50' Storage=0.000 af 0.1 cfs 0.0 cfs EWAM Type III 24-hr 25-year Rainfall=5.75"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 20HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 200P: East Total Inflow Area = 0.482 ac, 18.34% Impervious, Inflow Depth > 0.95" for 25-year event Inflow = 0.4 cfs @ 12.11 hrs, Volume= 0.038 af Primary = 0.4 cfs @ 12.11 hrs, Volume= 0.038 af, Atten= 0%, Lag= 0.0 min Routed to nonexistent node 201P Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Pond 200P: East Total Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.42 0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Inflow Area=0.482 ac 0.4 cfs 0.4 cfs EWAM Type III 24-hr 100-year Rainfall=7.10"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 21HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Yard West Runoff = 0.2 cfs @ 12.29 hrs, Volume= 0.038 af, Depth> 0.66" Routed to Pond 100P : West Total Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 100-year Rainfall=7.10" Area (sf) CN Description 597 98 Paved parking, HSG A 6,432 39 >75% Grass cover, Good, HSG A 21,248 30 Woods, Good, HSG A 1,294 98 Roofs, HSG A 308 98 Unconnected pavement, HSG A 29,879 37 Weighted Average 27,680 92.64% Pervious Area 2,199 7.36% Impervious Area 308 14.01% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 1S: Yard West Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.23 0.22 0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type III 24-hr 100-year Rainfall=7.10" Runoff Area=29,879 sf Runoff Volume=0.038 af Runoff Depth>0.66" Tc=6.0 min CN=37 0.2 cfs EWAM Type III 24-hr 100-year Rainfall=7.10"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 22HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Yard East Runoff = 0.8 cfs @ 12.10 hrs, Volume= 0.065 af, Depth> 1.63" Routed to Pond 200P : East Total Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 100-year Rainfall=7.10" Area (sf) CN Description 14,923 39 >75% Grass cover, Good, HSG A 2,456 98 Roofs, HSG A * 1,048 98 Driveway 2,215 30 Woods, Good, HSG A * 346 98 Walkways/Brick Patio 20,988 49 Weighted Average 17,138 81.66% Pervious Area 3,850 18.34% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 2S: Yard East Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 100-year Rainfall=7.10" Runoff Area=20,988 sf Runoff Volume=0.065 af Runoff Depth>1.63" Tc=6.0 min CN=49 0.8 cfs EWAM Type III 24-hr 100-year Rainfall=7.10"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 23HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 100P: West Total Inflow Area = 0.686 ac, 7.36% Impervious, Inflow Depth > 0.66" for 100-year event Inflow = 0.2 cfs @ 12.29 hrs, Volume= 0.038 af Outflow = 0.2 cfs @ 12.39 hrs, Volume= 0.037 af, Atten= 7%, Lag= 5.7 min Discarded = 0.2 cfs @ 12.39 hrs, Volume= 0.037 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 55.50' @ 12.39 hrs Surf.Area= 0.000 ac Storage= 0.000 af Plug-Flow detention time= 5.7 min calculated for 0.037 af (100% of inflow) Center-of-Mass det. time= 4.2 min ( 945.7 - 941.5 ) Volume Invert Avail.Storage Storage Description #1 55.50' 135,874.273 af Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (acres) (feet) (acre-feet) (acre-feet) (acres) 55.50 0.000 0.0 0.000 0.000 0.000 56.00 40.000 25.0 6.667 6.667 0.001 60.00 2,422.000 183.0 3,697.674 3,704.341 0.062 65.00 5,990.000 287.0 20,368.180 24,072.521 0.155 70.00 10,555.000 383.0 40,827.301 64,899.821 0.279 75.00 18,178.000 520.0 70,974.452 135,874.273 0.511 Device Routing Invert Outlet Devices #1 Discarded 55.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.0 cfs @ 12.39 hrs HW=55.50' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.0 cfs) EWAM Type III 24-hr 100-year Rainfall=7.10"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 24HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Pond 100P: West Total Inflow Discarded Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.23 0.22 0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Inflow Area=0.686 ac Peak Elev=55.50' Storage=0.000 af 0.2 cfs 0.2 cfs EWAM Type III 24-hr 100-year Rainfall=7.10"2023-05-04 5072600-PRE Printed 5/12/2023Prepared by BSC Group Page 25HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 200P: East Total Inflow Area = 0.482 ac, 18.34% Impervious, Inflow Depth > 1.63" for 100-year event Inflow = 0.8 cfs @ 12.10 hrs, Volume= 0.065 af Primary = 0.8 cfs @ 12.10 hrs, Volume= 0.065 af, Atten= 0%, Lag= 0.0 min Routed to nonexistent node 201P Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Pond 200P: East Total Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.482 ac 0.8 cfs 0.8 cfs Stormwater Narrative 25 Sumner Lane Brewster, MA 5.03 PROPOSED WATERSHED PLAN 40' WIDE SUMNER LANE 51,204± S.F. LOT 10 40 ' W I D E LA K E S H O R E D R I V E G G G G G W W W W W W S SS D 2S1S 349 Main Street - Route 28 West Yarmouth, Massachusetts 02673 508 778 8919 File: Dwg.: Scale: Job No.: Revised: Date: PREPARED FOR: 05/04/2023 DAVID & KAREN WHITNEY 25 SUMNER LANE BREWSTER, MASSACHUSETTS 02631 50726.00 1" = 30' 25 SUMNER LANE STORMWATER SUMNER LANE BREWSTER MASSACHUSETTS (BARNSTABLE COUNTY) MANAGEMENT IN C 2023 BSC Group, Inc. SCALE: FEET0153060 1" = 30' PROPOSED WATERSHED MAY 4, 2023 Stormwater Narrative 25 Sumner Lane Brewster, MA 5.04 PROPOSED HYDROLOGY CALCULATIONS (HYDROCAD™ PRINTOUTS) 1S Yard West 2S Yard East 200P East Total 206P Natural Bain 209P West Total Routing Diagram for 2023-05-03 5072600-POST Prepared by BSC Group, Printed 5/12/2023 HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Subcat Reach Pond Link PWAM 2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 2HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Rainfall Events Listing Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC 1 2-year Type III 24-hr Default 24.00 1 3.50 2 2 10-year Type III 24-hr Default 24.00 1 4.85 2 3 25-year Type III 24-hr Default 24.00 1 5.75 2 4 100-year Type III 24-hr Default 24.00 1 7.10 2 PWAM 2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 3HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 0.538 39 >75% Grass cover, Good, HSG A (1S, 2S) 0.016 98 Brick Patio/Walkways/Stairs (2S) 0.024 98 Driveways (2S) 0.071 98 Paved parking, HSG A (1S) 0.103 98 Roofs, HSG A (1S, 2S) 0.008 98 Unconnected pavement, HSG A (1S) 0.408 30 Woods, Good, HSG A (1S, 2S) 1.168 47 TOTAL AREA PWAM 2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 4HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Soil Listing (all nodes) Area (acres) Soil Group Subcatchment Numbers 1.128 HSG A 1S, 2S 0.000 HSG B 0.000 HSG C 0.000 HSG D 0.040 Other 2S 1.168 TOTAL AREA PWAM 2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 5HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Ground Covers (all nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.538 0.000 0.000 0.000 0.000 0.538 >75% Grass cover, Good 1S, 2S 0.000 0.000 0.000 0.000 0.016 0.016 Brick Patio/Walkways/Stairs 2S 0.000 0.000 0.000 0.000 0.024 0.024 Driveways 2S 0.071 0.000 0.000 0.000 0.000 0.071 Paved parking 1S 0.103 0.000 0.000 0.000 0.000 0.103 Roofs 1S, 2S 0.008 0.000 0.000 0.000 0.000 0.008 Unconnected pavement 1S 0.408 0.000 0.000 0.000 0.000 0.408 Woods, Good 1S, 2S 1.128 0.000 0.000 0.000 0.040 1.168 TOTAL AREA PWAM Type III 24-hr 2-year Rainfall=3.50"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 6HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Yard West Runoff = 0.0 cfs @ 14.74 hrs, Volume= 0.005 af, Depth> 0.08" Routed to Pond 206P : Natural Bain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 2-year Rainfall=3.50" Area (sf) CN Adj Description 3,085 98 Paved parking, HSG A 8,305 39 >75% Grass cover, Good, HSG A 15,717 30 Woods, Good, HSG A 2,385 98 Roofs, HSG A 356 98 Unconnected pavement, HSG A 29,848 46 45 Weighted Average, UI Adjusted 24,022 80.48% Pervious Area 5,826 19.52% Impervious Area 356 6.11% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 1S: Yard West Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.009 0.008 0.007 0.007 0.006 0.006 0.005 0.005 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.001 0.000 0 Type III 24-hr 2-year Rainfall=3.50" Runoff Area=29,848 sf Runoff Volume=0.005 af Runoff Depth>0.08" Tc=6.0 min UI Adjusted CN=45 0.0 cfs PWAM Type III 24-hr 2-year Rainfall=3.50"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 7HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Yard East Runoff = 0.0 cfs @ 12.43 hrs, Volume= 0.007 af, Depth> 0.17" Routed to Pond 200P : East Total Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 2-year Rainfall=3.50" Area (sf) CN Description 15,137 39 >75% Grass cover, Good, HSG A 2,110 98 Roofs, HSG A * 1,050 98 Driveways 2,040 30 Woods, Good, HSG A * 696 98 Brick Patio/Walkways/Stairs 21,033 49 Weighted Average 17,177 81.67% Pervious Area 3,856 18.33% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 2S: Yard East Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.023 0.022 0.021 0.02 0.019 0.018 0.017 0.016 0.015 0.014 0.013 0.012 0.011 0.01 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0 Type III 24-hr 2-year Rainfall=3.50" Runoff Area=21,033 sf Runoff Volume=0.007 af Runoff Depth>0.17" Tc=6.0 min CN=49 0.0 cfs PWAM Type III 24-hr 2-year Rainfall=3.50"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 8HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 200P: East Total Inflow Area = 0.483 ac, 18.33% Impervious, Inflow Depth > 0.17" for 2-year event Inflow = 0.0 cfs @ 12.43 hrs, Volume= 0.007 af Primary = 0.0 cfs @ 12.43 hrs, Volume= 0.007 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Pond 200P: East Total Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.023 0.022 0.021 0.02 0.019 0.018 0.017 0.016 0.015 0.014 0.013 0.012 0.011 0.01 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0 Inflow Area=0.483 ac 0.0 cfs 0.0 cfs PWAM Type III 24-hr 2-year Rainfall=3.50"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 9HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 206P: Natural Bain Inflow Area = 0.685 ac, 19.52% Impervious, Inflow Depth > 0.08" for 2-year event Inflow = 0.0 cfs @ 14.74 hrs, Volume= 0.005 af Outflow = 0.0 cfs @ 14.82 hrs, Volume= 0.005 af, Atten= 0%, Lag= 4.7 min Discarded = 0.0 cfs @ 14.82 hrs, Volume= 0.005 af Primary = 0.0 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Pond 209P : West Total Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 59.50' @ 14.82 hrs Surf.Area= 0.000 ac Storage= 0.000 af Plug-Flow detention time= 4.5 min calculated for 0.005 af (100% of inflow) Center-of-Mass det. time= 2.9 min ( 1,057.1 - 1,054.2 ) Volume Invert Avail.Storage Storage Description #1 59.50' 52,313.876 af Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (acres) (feet) (acre-feet) (acre-feet) (acres) 59.50 0.000 0.0 0.000 0.000 0.000 60.00 16.000 20.0 2.667 2.667 0.001 65.00 1,225.000 140.0 2,301.667 2,304.333 0.037 70.00 4,088.000 235.0 12,584.686 14,889.019 0.106 75.00 11,508.000 441.0 37,424.857 52,313.876 0.363 Device Routing Invert Outlet Devices #1 Discarded 59.50'8.270 in/hr Exfiltration over Surface area #2 Primary 74.50'10.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.0 cfs @ 14.82 hrs HW=59.50' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.0 cfs) Primary OutFlow Max=0.0 cfs @ 0.00 hrs HW=59.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.0 cfs) PWAM Type III 24-hr 2-year Rainfall=3.50"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 10HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Pond 206P: Natural Bain Inflow Outflow Discarded Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.009 0.008 0.007 0.007 0.006 0.006 0.005 0.005 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.001 0.000 0 Inflow Area=0.685 ac Peak Elev=59.50' Storage=0.000 af 0.0 cfs 0.0 cfs 0.0 cfs 0.0 cfs PWAM Type III 24-hr 2-year Rainfall=3.50"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 11HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 209P: West Total Inflow Area = 0.685 ac, 19.52% Impervious, Inflow Depth = 0.00" for 2-year event Inflow = 0.0 cfs @ 0.00 hrs, Volume= 0.000 af Primary = 0.0 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Pond 209P: West Total Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 1 0 Inflow Area=0.685 ac 0.0 cfs 0.0 cfs PWAM Type III 24-hr 10-year Rainfall=4.85"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 12HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Yard West Runoff = 0.1 cfs @ 12.32 hrs, Volume= 0.023 af, Depth> 0.39" Routed to Pond 206P : Natural Bain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 10-year Rainfall=4.85" Area (sf) CN Adj Description 3,085 98 Paved parking, HSG A 8,305 39 >75% Grass cover, Good, HSG A 15,717 30 Woods, Good, HSG A 2,385 98 Roofs, HSG A 356 98 Unconnected pavement, HSG A 29,848 46 45 Weighted Average, UI Adjusted 24,022 80.48% Pervious Area 5,826 19.52% Impervious Area 356 6.11% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 1S: Yard West Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.125 0.12 0.115 0.11 0.105 0.1 0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Type III 24-hr 10-year Rainfall=4.85" Runoff Area=29,848 sf Runoff Volume=0.023 af Runoff Depth>0.39" Tc=6.0 min UI Adjusted CN=45 0.1 cfs PWAM Type III 24-hr 10-year Rainfall=4.85"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 13HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Yard East Runoff = 0.2 cfs @ 12.13 hrs, Volume= 0.023 af, Depth> 0.58" Routed to Pond 200P : East Total Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 10-year Rainfall=4.85" Area (sf) CN Description 15,137 39 >75% Grass cover, Good, HSG A 2,110 98 Roofs, HSG A * 1,050 98 Driveways 2,040 30 Woods, Good, HSG A * 696 98 Brick Patio/Walkways/Stairs 21,033 49 Weighted Average 17,177 81.67% Pervious Area 3,856 18.33% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 2S: Yard East Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type III 24-hr 10-year Rainfall=4.85" Runoff Area=21,033 sf Runoff Volume=0.023 af Runoff Depth>0.58" Tc=6.0 min CN=49 0.2 cfs PWAM Type III 24-hr 10-year Rainfall=4.85"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 14HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 200P: East Total Inflow Area = 0.483 ac, 18.33% Impervious, Inflow Depth > 0.58" for 10-year event Inflow = 0.2 cfs @ 12.13 hrs, Volume= 0.023 af Primary = 0.2 cfs @ 12.13 hrs, Volume= 0.023 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Pond 200P: East Total Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Inflow Area=0.483 ac 0.2 cfs 0.2 cfs PWAM Type III 24-hr 10-year Rainfall=4.85"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 15HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 206P: Natural Bain Inflow Area = 0.685 ac, 19.52% Impervious, Inflow Depth > 0.39" for 10-year event Inflow = 0.1 cfs @ 12.32 hrs, Volume= 0.023 af Outflow = 0.1 cfs @ 12.40 hrs, Volume= 0.022 af, Atten= 5%, Lag= 4.5 min Discarded = 0.1 cfs @ 12.40 hrs, Volume= 0.022 af Primary = 0.0 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Pond 209P : West Total Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 59.50' @ 12.40 hrs Surf.Area= 0.000 ac Storage= 0.000 af Plug-Flow detention time= 4.5 min calculated for 0.022 af (100% of inflow) Center-of-Mass det. time= 3.3 min ( 954.3 - 951.0 ) Volume Invert Avail.Storage Storage Description #1 59.50' 52,313.876 af Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (acres) (feet) (acre-feet) (acre-feet) (acres) 59.50 0.000 0.0 0.000 0.000 0.000 60.00 16.000 20.0 2.667 2.667 0.001 65.00 1,225.000 140.0 2,301.667 2,304.333 0.037 70.00 4,088.000 235.0 12,584.686 14,889.019 0.106 75.00 11,508.000 441.0 37,424.857 52,313.876 0.363 Device Routing Invert Outlet Devices #1 Discarded 59.50'8.270 in/hr Exfiltration over Surface area #2 Primary 74.50'10.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.0 cfs @ 12.40 hrs HW=59.50' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.0 cfs) Primary OutFlow Max=0.0 cfs @ 0.00 hrs HW=59.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.0 cfs) PWAM Type III 24-hr 10-year Rainfall=4.85"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 16HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Pond 206P: Natural Bain Inflow Outflow Discarded Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Inflow Area=0.685 ac Peak Elev=59.50' Storage=0.000 af 0.1 cfs 0.1 cfs 0.1 cfs 0.0 cfs PWAM Type III 24-hr 10-year Rainfall=4.85"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 17HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 209P: West Total Inflow Area = 0.685 ac, 19.52% Impervious, Inflow Depth = 0.00" for 10-year event Inflow = 0.0 cfs @ 0.00 hrs, Volume= 0.000 af Primary = 0.0 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Pond 209P: West Total Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 1 0 Inflow Area=0.685 ac 0.0 cfs 0.0 cfs PWAM Type III 24-hr 25-year Rainfall=5.75"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 18HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Yard West Runoff = 0.3 cfs @ 12.13 hrs, Volume= 0.040 af, Depth> 0.70" Routed to Pond 206P : Natural Bain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 25-year Rainfall=5.75" Area (sf) CN Adj Description 3,085 98 Paved parking, HSG A 8,305 39 >75% Grass cover, Good, HSG A 15,717 30 Woods, Good, HSG A 2,385 98 Roofs, HSG A 356 98 Unconnected pavement, HSG A 29,848 46 45 Weighted Average, UI Adjusted 24,022 80.48% Pervious Area 5,826 19.52% Impervious Area 356 6.11% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 1S: Yard West Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 25-year Rainfall=5.75" Runoff Area=29,848 sf Runoff Volume=0.040 af Runoff Depth>0.70" Tc=6.0 min UI Adjusted CN=45 0.3 cfs PWAM Type III 24-hr 25-year Rainfall=5.75"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 19HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Yard East Runoff = 0.4 cfs @ 12.11 hrs, Volume= 0.038 af, Depth> 0.95" Routed to Pond 200P : East Total Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 25-year Rainfall=5.75" Area (sf) CN Description 15,137 39 >75% Grass cover, Good, HSG A 2,110 98 Roofs, HSG A * 1,050 98 Driveways 2,040 30 Woods, Good, HSG A * 696 98 Brick Patio/Walkways/Stairs 21,033 49 Weighted Average 17,177 81.67% Pervious Area 3,856 18.33% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 2S: Yard East Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.42 0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 25-year Rainfall=5.75" Runoff Area=21,033 sf Runoff Volume=0.038 af Runoff Depth>0.95" Tc=6.0 min CN=49 0.4 cfs PWAM Type III 24-hr 25-year Rainfall=5.75"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 20HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 200P: East Total Inflow Area = 0.483 ac, 18.33% Impervious, Inflow Depth > 0.95" for 25-year event Inflow = 0.4 cfs @ 12.11 hrs, Volume= 0.038 af Primary = 0.4 cfs @ 12.11 hrs, Volume= 0.038 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Pond 200P: East Total Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.42 0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Inflow Area=0.483 ac 0.4 cfs 0.4 cfs PWAM Type III 24-hr 25-year Rainfall=5.75"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 21HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 206P: Natural Bain Inflow Area = 0.685 ac, 19.52% Impervious, Inflow Depth > 0.70" for 25-year event Inflow = 0.3 cfs @ 12.13 hrs, Volume= 0.040 af Outflow = 0.3 cfs @ 12.26 hrs, Volume= 0.040 af, Atten= 17%, Lag= 7.9 min Discarded = 0.3 cfs @ 12.26 hrs, Volume= 0.040 af Primary = 0.0 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Pond 209P : West Total Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 59.50' @ 12.26 hrs Surf.Area= 0.001 ac Storage= 0.000 af Plug-Flow detention time= 4.5 min calculated for 0.040 af (100% of inflow) Center-of-Mass det. time= 3.4 min ( 925.4 - 922.0 ) Volume Invert Avail.Storage Storage Description #1 59.50' 52,313.876 af Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (acres) (feet) (acre-feet) (acre-feet) (acres) 59.50 0.000 0.0 0.000 0.000 0.000 60.00 16.000 20.0 2.667 2.667 0.001 65.00 1,225.000 140.0 2,301.667 2,304.333 0.037 70.00 4,088.000 235.0 12,584.686 14,889.019 0.106 75.00 11,508.000 441.0 37,424.857 52,313.876 0.363 Device Routing Invert Outlet Devices #1 Discarded 59.50'8.270 in/hr Exfiltration over Surface area #2 Primary 74.50'10.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.0 cfs @ 12.26 hrs HW=59.50' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.0 cfs) Primary OutFlow Max=0.0 cfs @ 0.00 hrs HW=59.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.0 cfs) PWAM Type III 24-hr 25-year Rainfall=5.75"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 22HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Pond 206P: Natural Bain Inflow Outflow Discarded Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Inflow Area=0.685 ac Peak Elev=59.50' Storage=0.000 af 0.3 cfs 0.3 cfs 0.3 cfs 0.0 cfs PWAM Type III 24-hr 25-year Rainfall=5.75"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 23HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 209P: West Total Inflow Area = 0.685 ac, 19.52% Impervious, Inflow Depth = 0.00" for 25-year event Inflow = 0.0 cfs @ 0.00 hrs, Volume= 0.000 af Primary = 0.0 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Pond 209P: West Total Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 1 0 Inflow Area=0.685 ac 0.0 cfs 0.0 cfs PWAM Type III 24-hr 100-year Rainfall=7.10"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 24HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Yard West Runoff = 0.8 cfs @ 12.11 hrs, Volume= 0.073 af, Depth> 1.28" Routed to Pond 206P : Natural Bain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 100-year Rainfall=7.10" Area (sf) CN Adj Description 3,085 98 Paved parking, HSG A 8,305 39 >75% Grass cover, Good, HSG A 15,717 30 Woods, Good, HSG A 2,385 98 Roofs, HSG A 356 98 Unconnected pavement, HSG A 29,848 46 45 Weighted Average, UI Adjusted 24,022 80.48% Pervious Area 5,826 19.52% Impervious Area 356 6.11% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 1S: Yard West Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 100-year Rainfall=7.10" Runoff Area=29,848 sf Runoff Volume=0.073 af Runoff Depth>1.28" Tc=6.0 min UI Adjusted CN=45 0.8 cfs PWAM Type III 24-hr 100-year Rainfall=7.10"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 25HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Yard East Runoff = 0.8 cfs @ 12.10 hrs, Volume= 0.066 af, Depth> 1.63" Routed to Pond 200P : East Total Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type III 24-hr 100-year Rainfall=7.10" Area (sf) CN Description 15,137 39 >75% Grass cover, Good, HSG A 2,110 98 Roofs, HSG A * 1,050 98 Driveways 2,040 30 Woods, Good, HSG A * 696 98 Brick Patio/Walkways/Stairs 21,033 49 Weighted Average 17,177 81.67% Pervious Area 3,856 18.33% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, MIN TC Subcatchment 2S: Yard East Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 100-year Rainfall=7.10" Runoff Area=21,033 sf Runoff Volume=0.066 af Runoff Depth>1.63" Tc=6.0 min CN=49 0.8 cfs PWAM Type III 24-hr 100-year Rainfall=7.10"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 26HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 200P: East Total Inflow Area = 0.483 ac, 18.33% Impervious, Inflow Depth > 1.63" for 100-year event Inflow = 0.8 cfs @ 12.10 hrs, Volume= 0.066 af Primary = 0.8 cfs @ 12.10 hrs, Volume= 0.066 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Pond 200P: East Total Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.483 ac 0.8 cfs 0.8 cfs PWAM Type III 24-hr 100-year Rainfall=7.10"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 27HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 206P: Natural Bain Inflow Area = 0.685 ac, 19.52% Impervious, Inflow Depth > 1.28" for 100-year event Inflow = 0.8 cfs @ 12.11 hrs, Volume= 0.073 af Outflow = 0.6 cfs @ 12.18 hrs, Volume= 0.073 af, Atten= 19%, Lag= 4.1 min Discarded = 0.6 cfs @ 12.18 hrs, Volume= 0.073 af Primary = 0.0 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Pond 209P : West Total Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Peak Elev= 59.51' @ 12.18 hrs Surf.Area= 0.004 ac Storage= 0.000 af Plug-Flow detention time= 4.5 min calculated for 0.073 af (100% of inflow) Center-of-Mass det. time= 3.6 min ( 900.1 - 896.6 ) Volume Invert Avail.Storage Storage Description #1 59.50' 52,313.876 af Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (acres) (feet) (acre-feet) (acre-feet) (acres) 59.50 0.000 0.0 0.000 0.000 0.000 60.00 16.000 20.0 2.667 2.667 0.001 65.00 1,225.000 140.0 2,301.667 2,304.333 0.037 70.00 4,088.000 235.0 12,584.686 14,889.019 0.106 75.00 11,508.000 441.0 37,424.857 52,313.876 0.363 Device Routing Invert Outlet Devices #1 Discarded 59.50'8.270 in/hr Exfiltration over Surface area #2 Primary 74.50'10.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.0 cfs @ 12.18 hrs HW=59.51' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.0 cfs) Primary OutFlow Max=0.0 cfs @ 0.00 hrs HW=59.50' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.0 cfs) PWAM Type III 24-hr 100-year Rainfall=7.10"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 28HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Pond 206P: Natural Bain Inflow Outflow Discarded Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.685 ac Peak Elev=59.51' Storage=0.000 af 0.8 cfs 0.6 cfs 0.6 cfs 0.0 cfs PWAM Type III 24-hr 100-year Rainfall=7.10"2023-05-03 5072600-POST Printed 5/12/2023Prepared by BSC Group Page 29HydroCAD® 10.20-2f s/n 00904 © 2022 HydroCAD Software Solutions LLC Summary for Pond 209P: West Total Inflow Area = 0.685 ac, 19.52% Impervious, Inflow Depth = 0.00" for 100-year event Inflow = 0.0 cfs @ 0.00 hrs, Volume= 0.000 af Primary = 0.0 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Pond 209P: West Total Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210 Fl o w ( c f s ) 1 0 Inflow Area=0.685 ac 0.0 cfs 0.0 cfs Stormwater Narrative 25 Sumner Lane Brewster, MA SECTION 6.0 ADDITIONAL DRAINAGE CALCULATIONS Stormwater Narrative 25 Sumner Lane Brewster, MA 6.01 WATER QUALITY VOLUME CALCULATION VWQ = (DWQ/12 inches/foot) * (AIMP square feet) VWQ = Required Water Quality Volume (in cubic feet) DWQ = Water Quality Depth: 1.0-inch AIMP = Total Impervious Area (in acres) used for driveways, parking, etc. AIMP = 9,682sq.ft. VWQ = (1.0 inches/12 inches/foot) * (9,682 sq.ft.) VWQ = 806.83 cubic feet (required volume) The natural depression, which will be utilized for stormwater management purposes, has more than sufficient capacity to meet the required treatment volume for this project. Stormwater Narrative 25 Sumner Lane Brewster, MA APPENDIX A USGS LOCUS MAP Stormwater Narrative 25 Sumner Lane Brewster, MA APPENDIX B FEMA MAP National Flood Hazard Layer FIRMette 0 500 1,000 1,500 2,000250 Feet Ü SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT SPECIAL FLOOD HAZARD AREAS Without Base Flood Elevation (BFE) Zone A, V, A99 With BFE or DepthZone AE, AO, AH, VE, AR Regulatory Floodway 0.2% Annual Chance Flood Hazard, Areas of 1% annual chance flood with average depth less than one foot or with drainage areas of less than one square mileZone X Future Conditions 1% Annual Chance Flood HazardZone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to LeveeZone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood HazardZone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA. This map was exported on 5/5/2023 at 10:26 AM and does not reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or become superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes. Legend OTHER AREAS OF FLOOD HAZARD OTHER AREAS GENERAL STRUCTURES OTHER FEATURES MAP PANELS 8 B 20.2 The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative property location. 1:6,000 70°5'29"W 41°43'54"N 70°4'51"W 41°43'27"N Basemap: USGS National Map: Orthoimagery: Data refreshed October, 2020 Stormwater Narrative 25 Sumner Lane Brewster, MA APPENDIX C WEB SOIL SURVEY Hydrologic Soil Group—Barnstable County, Massachusetts (25 Sumner Lane) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/5/2023 Page 1 of 4 461 9 9 1 0 461 9 9 8 0 462 0 0 5 0 462 0 1 2 0 462 0 1 9 0 462 0 2 6 0 462 0 3 3 0 461 9 9 1 0 461 9 9 8 0 462 0 0 5 0 462 0 1 2 0 462 0 1 9 0 462 0 2 6 0 409360 409430 409500 409570 409640 409710 409780 409850 409920 409990 409360 409430 409500 409570 409640 409710 409780 409850 409920 409990 41° 43' 46'' N 70° 5 ' 2 3 ' ' W 41° 43' 46'' N 70° 4 ' 5 5 ' ' W 41° 43' 32'' N 70° 5 ' 2 3 ' ' W 41° 43' 32'' N 70° 4 ' 5 5 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 19N WGS84 0 100 200 400 600 Feet 0 40 80 160 240 Meters Map Scale: 1:2,990 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available 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 19, Sep 9, 2022 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jun 10, 2022—Jun 30, 2022 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. Hydrologic Soil Group—Barnstable County, Massachusetts (25 Sumner Lane) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/5/2023 Page 2 of 4 Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 1 Water 2.0 5.3% 252A Carver coarse sand, 0 to 3 percent slopes A 0.1 0.3% 252D Carver coarse sand, 15 to 35 percent slopes A 25.0 66.1% 600 Pits, sand and gravel 1.6 4.3% 665 Udipsamments, smoothed 9.1 24.0% Totals for Area of Interest 37.8 100.0% Hydrologic Soil Group—Barnstable County, Massachusetts 25 Sumner Lane Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/5/2023 Page 3 of 4 Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—Barnstable County, Massachusetts 25 Sumner Lane Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 5/5/2023 Page 4 of 4 Stormwater Narrative 25 Sumner Lane Brewster, MA APPENDIX D MASSDEP STORMWATER CHECKLIST Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 1 of 8 Important: When filling out forms on the computer, use only the tab key to move your cursor - do not use the return key. A. Introduction A Stormwater Report must be submitted with the Notice of Intent permit application to document compliance with the Stormwater Management Standards. The following checklist is NOT a substitute for the Stormwater Report (which should provide more substantive and detailed information) but is offered here as a tool to help the applicant organize their Stormwater Management documentation for their Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist, the Stormwater Report must contain the engineering computations and supporting information set forth in Volume 3 of the Massachusetts Stormwater Handbook. The Stormwater Report must be prepared and certified by a Registered Professional Engineer (RPE) licensed in the Commonwealth. The Stormwater Report must include: • The Stormwater Checklist completed and stamped by a Registered Professional Engineer (see page 2) that certifies that the Stormwater Report contains all required submittals.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 (LUH PPL), 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 se t 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 i n the Stormwater Report. In that event, the issuing authority has the discretion to issue an Order of Conditions that approves the project and includes a condition requiring the proponent to submit the Construction Period Erosion and Sedimentation Control Plan before commencing any land disturbance activity on the site. Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 2 of 8 B. Stormwater Checklist and Certification The following checklist is intended to serve as a guide for applicants as to the elements that ordinarily need to be addressed in a complete Stormwater Report. The checklist is also intended to provide conservation commissions and other reviewing authorities with a summary of the components necessary for a comprehensive Stormwater Report that addresses the ten Stormwater Standards. Note: Because stormwater requirements vary from project to project, it is possible that a complete Stormwater Report may not include information on some of the subjects specified in the Checklist. If it is determined that a specific item does not apply to the project under review, please note that the item is not applicable (N.A.) and provide the reasons for that determination. A complete checklist must include the Certification set forth below signed by the Registered Professional Engineer who prepared the Stormwater Report. Registered Professional Engineer’s Certification I have reviewed the Stormwater Report, including the soil evaluation, computations, Long-term Pollution Prevention Plan, the Construction Period Erosion and Sedimentation Control Plan (if included), the Long- term Post-Construction Operation and Maintenance Plan, the Illicit Discharge Compliance Statement (if included) and the plans showing the stormwater management system, and have determined that they have been prepared in accordance with the requirements of the Stormwater Management Standards as further elaborated by the Massachusetts Stormwater Handbook. I have also determined that the information presented in the Stormwater Checklist is accurate and that the informat ion presented in the Stormwater Report accurately reflects conditions at the site as of the date of this permit application. Registered Professional Engineer Block and Signature Signature and Date Checklist Project Type: Is the application for new development, redevelopment, or a mix of new and redevelopment? New development Redevelopment Mix of New Development and Redevelopment Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 3 of 8 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 Infiltration Basin 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. Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 4 of 8 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. Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 5 of 8 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. Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 6 of 8 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. Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 7 of 8 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. Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 8 of 8 Checklist (continued) Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control (continued) The project is highly complex and information is included in the Stormwater Report that explains why it is not possible to submit the Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan with the application. A Construction Period Pollution Prevention and Erosion and Sedimentation Control has not been included in the Stormwater Report but will be submitted before land disturbance begins. The project is not covered by a NPDES Construction General Permit. The project is covered by a NPDES Construction General Permit and a copy of the SWPPP is in the Stormwater Report. The project is covered by a NPDES Construction General Permit but no SWPPP been submitted. The SWPPP will be submitted BEFORE land disturbance begins. Standard 9: Operation and Maintenance Plan The Post Construction Operation and Maintenance Plan is included in the Stormwater Report and includes the following information: Name of the stormwater management system owners; Party responsible for operation and maintenance; Schedule for implementation of routine and non-routine maintenance tasks; Plan showing the location of all stormwater BMPs maintenance access areas; Description and delineation of public safety features; Estimated operation and maintenance budget; and Operation and Maintenance Log Form. The responsible party is not the owner of the parcel where the BMP is located and the Stormwater Report includes the following submissions: A copy of the legal instrument (deed, homeowner’s association, utility trust or other legal entity) that establishes the terms of and legal responsibility for the operation and maintenance of the project site stormwater BMPs; A plan and easement deed that allows site access for the legal entity to operate and maintain BMP functions. Standard 10: Prohibition of Illicit Discharges The Long-Term Pollution Prevention Plan includes measures to prevent illicit discharges; An Illicit Discharge Compliance Statement is attached; NO Illicit Discharge Compliance Statement is attached but will be submitted prior to the discharge of any stormwater to post-construction BMPs. MAJOR STORMWATER MANAGEMENT PERMIT CASE NO. 2023-20 APPLICANT/OWNER: 178 BONNIE DOONE CARTWAY, LLC PROPERTY: 178 BONNIE DOONE CARTWAY 178 Bonnie Doone SWMP23-20 Staff Report Page 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 SWMP23-20 178 Bonnie Doone Cartway (Map 102 Parcel 13) Applicant, 178 Bonnie Doone Cartway LLC c/o John M. O’Reilly, PE, PLS DATE: June 5, 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; and subject to further conservation commission review and approval of the roof run-off leaching galley located in the 50’-100’ wetland buffer, shown on the site plan. In addition, Modification of the Major Stormwater Permit would be required for construction of the future proposed dwelling and garage as depicted on the site plan. Major Stormwater Management Permit The underlying project is redevelopment of a previously developed residential property with a number of dwellings, accessory buildings and supporting appurtenances. The property is nonconforming in terms of zoning because it contains several pre-existing, detached dwellings. Major Stormwater Permits are subject to review at a public meeting, including for any waivers requested. This project triggers a Stormwater Permit under Chapter 272 of the Brewster Code (Stormwater Management Bylaw) and according to Section 4 of the Bylaw’s supporting regulations, a Major Stormwater Permit is required because the project involves net new impervious surface of 2500 sq ft or greater and alternately, 20,000 sq ft or more of total site disturbance. Prior to the effective date of the Stormwater Management Bylaw, the zoning board of appeals granted a special permit for the project, the conservation commission issued an order of conditions, the Board of Health/ Health Department issued disposal works construction permits for the septic systems, and several building permits were issued consistent with those approvals. Because the project involves a number of different buildings and structures, building permits for some the approved buildings and structures have not yet issued. The property is approximately 9.5 acres and is bounded by Bonnie Doone Cartway, an unimproved private subdivision way, to the west, Cape Cod Bay to the north, and Town property to the east. The area of the site along Cape Cod Bay contains coastal wetlands resources such as dune and some special flood hazard zones. There are vegetated wetlands in and to the south of the site. The property is not located in a Zone II or the DCPC. Office of: Planning Board Planning Dept. 178 Bonnie Doone SWMP23-20 Staff Report Page 2 Pursuant to the above-referenced zoning and wetlands approvals, much of the existing site development was required to locate further from wetlands and floodplain areas on-site or outside wetland buffers altogether. In fact, under the Wetlands Order of Conditions, the Applicant is required to remove the existing, northernmost cottage on the site as mitigation for its proposal. Based on discussions between the Natural Resources and Planning Departments, and the particular circumstances present in the matter, the departments decided that the Planning Board was the more appropriate Stormwater Permitting Authority, where most of the proposed development is located outside wetlands jurisdiction. Drainage patterns on the site are complex and the site contains several drainage watersheds. The site stormwater management approach accounts for these patterns and consists of subsurface infiltration facilities to handle building roof run-off separately from site run-off; and vegetated swales (including an existing natural depression) to treat and infiltrate site run-off, all as shown on the site plan. Planting and landscaping details for the swales and site have been provided with the application. Once the grass in the swales, a conservation seed mix, has become established, the areas will be supplemented with native trees, shrubs, and native forbs and grasses. Landscape site designs are in the process of being prepared. Any fertilizer used will be organic type and will be limited to the initial planting of the grass and subsequent shrubs and trees. The Applicant has provided the required application materials for a Major Stormwater Permit, including a site plan and Stormwater Management Report with HydroCad analysis (both dated 5/17/23), as set out in Appendix B of the Stormwater Management Regulations. No waivers from the Bylaw/ Regulations have been requested or identified as necessary. The Stormwater Management approach meets the applicable standards in relevant Sections 6.1B and 6.2B of Brewster’s Stormwater Regulations, including consistency with the State Stormwater handbook standards:  The system was designed under post-development conditions to maintain stormwater recharge capacity on-site for the 2, 10, 25 and 100-year storm events;  As designed, post-development runoff rates are reduced to less than the pre-development conditions including for the 100-year storm;  The Applicant has provided an Operations and Maintenance Manual that sets out proper, long- term procedures to maintain the proposed post-construction BMPs;  The Applicant has provided an appropriate construction-period erosion and sedimentation control plan;  The site stormwater approach incorporates Low Impact Development-type (LID) stormwater design elements;  The site systems provide the required TSS and Phosphorus treatment, including through “first flush” water quality volume retention;  The Applicant’s soil tests on the property, and NRCS mapping, have revealed sandy and well- draining soils.  There is sufficient vertical separation between the stormwater facilities and groundwater to allow proper system function, at least one feet in all cases. STORMWATER MANAGEMENT REPORT AND OPERATIONS & MAINTENANCE MANUAL 178 BONNIE DOONE CARTWAY, LLC 178 BONNIE DOONE CARTWAY, BREWSTER, MA ASSESSORS MAP 102, PARCEL 13 May 17, 2023 PREPARED FOR: 178 Bonnie Doone Cartway, LLC PREPARED BY: J.M. O’REILLY & ASSOCIATES, INC. 1573 MAIN STREET P.O. BOX 1773 BREWSTER, MA 02631 508-896-6601 Page 2 of 10 178 BONNIE DOONE CARTWAY LLC STORMWATER MANAGEMENT REPORT BONNIE DOONE CARTWAY, BREWSTER, MA MAY 17, 2023 JMO-8705 TABLE OF CONTENTS 1. Property Description and Information 2. Stormwater Management System Description 3. Pre Versus Post peak Discharge Rates; volumes requirements & Nutrient Treatment 4. Owner and Responsible Party 5. Schedule of Inspection and Maintenance of System 6. Long Term Lawn Care & Pollution Prevention Plan 7. Emergency Spill Cleanup Plan 8. ATTACHMENTS A – TSS Removal Calculation Sheets (Roof and Driveway) B – Routing Diagram from HydroCAD Report with Pre versus Post Discharge C – Site Plan with Watershed Plan Page 3 of 10 178 BONNIE DOONE CARTWAY LLC STORMWATER MANAGEMENT REPORT BONNIE DOONE CARTWAY, BREWSTER, MA MAY 17, 2023 JMO-8705 Property Description: Lot Area: 412,078 sf+/- (9.46 ACRES) Parcel Improvements: The site was to be developed with four cottages, a driveway and utilities. Currently the site is under construction for the one remaining cottage and two new single family dwellings. Wetlands: The parcel abuts Cape Cod Bay. The landward resource on the property is a Coastal Dune. The project has received approval for the alterations within the 100 foot Buffer Zone from the Coastal Dune. There is also a vegetated wetland in the southeast corner of the parcel and a larger vegetated wetland along the southern property line. Most of the new construction takes place beyond the 100 foot Buffer Zone. Please refer to the Site Plan. Soils: Soil testing on the parcel for the sewage system design reflected sandy and loamy sands within the development area. Refer to the Site Plan and the soil logs. Groundwater: The groundwater was encountered at elevation 18.1. Zone II: The parcel is NOT located within a Zone II Groundwater Recharge mapped area. Topography: The topography is rolling and provides for several watersheds within the water shed of the development area. Elevations range from 21 up to 30 within the development area of the proposed homes and driveways. Site Conditions: The existing lot is currently altered with the construction of a single family dwelling (second dwelling in from Bonnie Doone). The sewage systems have been installed along with the proposed driveway constructed. The site is well organized and graded to mitigate washout of the exposed soils during the construction phase. Stormwater Management System Description: The proposed post-development stormwater management plan consists of two (2) separate stormwater systems that together have been designed to retain and attenuate stormwater runoff from all impervious and landscaped surfaces on the site, including the driveway, dwelling, Landscaped Areas, and Natural Areas. Stormwater systems have been designed to meet the 100-year storm event. Wetland & Buffer Zone Watershed: The first watershed (#1) includes the wetland resources along the Bay and the 100 foot Buffer areas. There are no stormwater systems proposed within this watershed. The water shed contains four cottages including driveways and paths to the beach. The approvals for the project require three of the four cottages be removed and the area vegetated with native shrubs, grasses and trees. The removal of the three cottages is sufficient mitigation to address the pre versus the post peak discharges. The cottage will have some roof runoff control, as associated with the Orders of Conditions, but with the elimination of the other roofed areas, the watershed can support the direct discharge of the roof water runoff. Page 4 of 10 178 BONNIE DOONE CARTWAY LLC STORMWATER MANAGEMENT REPORT BONNIE DOONE CARTWAY, BREWSTER, MA MAY 17, 2023 JMO-8705 The nutrient loading and TSS calculations have not been prepared for the Watershed. The area is 95% native vegetation cover with only 1,200 sf of hardscape and roof area. The intent of the development was to pull the proposed homes away from the Buffer Area and provide a significant native buffer to the Bay. Development Area Watershed: The second watershed (#2) includes most of the new alterations to the property. The proposed alterations include the development of three single family homes (replaces the removed cottages), a gravel driveway with a fire department turnaround, sewage system, utilities, grading and landscape. Watershed #2 is a large area (3.2 ac) which ultimately feeds down to the natural low point to the south of the first proposed single family dwelling. The stormwater control design breaks the contributory area up into several smaller water sheds. The smaller water sheds are designed to take advantage of site conditions to mitigate and reduce the contributory area to the natural low point of the watershed. The first sub-watershed is at the entrance off Bonnie Doone Cartway and south of the proposed driveway. The proposal is to construct a large shallow grassed swale which will accept and control the runoff from the woodlands to the south. The second sub-watershed is the fire loop – driveway area. The proposal is to construct a shallow grassed swale, adjacent to the 2-car garage, currently under construction. The swale is designed to accept runoff from the looped fire lane – driveway and the adjacent vegetated areas. The third sub water shed is the area of the third single family home and the surrounding areas. The proposed third dwelling is not slated to be built till the first two homes are constructed. It would be the intention of modifying the Stormwater Permit when the decision is made to move forward with the third new home. The third sub-watershed currently contains several low points which are sufficiently sized to address the stormwater runoff from the existing disturbed areas and the surrounding wooded areas All three sub-watersheds eventually discharge down towards the natural low point, south the first single family home. 90% of the natural low point will remain unaltered and is sufficiently sized to address the 100-year storm event. The large natural low point provides 0 cfs of peak discharge. Stormwater Controls for Roof Areas: The stormwater controls for the roofed areas are designed to handle the 100-year storm event. The three roofed structures include the first and second new single family homes and the 2-car garage for the second single family home. The second single family home and the detached garage are under construction. The entire roof runoff will be controlled by gutters, downspouts and a subsurface leaching galley (two separate systems). The leaching galleys are designed for the 100-year storm. As shown in the HydroCAD reports, both Watersheds have been prepared to reflect a reduction of peak discharge for the 100-year storm event. The table below provides a comparison of the site-wide Pre- to Post-Development peak discharge rate for each storm event. Page 5 of 10 178 BONNIE DOONE CARTWAY LLC STORMWATER MANAGEMENT REPORT BONNIE DOONE CARTWAY, BREWSTER, MA MAY 17, 2023 JMO-8705 Storm Event Pre-Development Peak Discharge Rate, cubic feet per second (ft3/sec) Post-Development Peak Discharge Rate, cubic feet per second (ft3/sec) Watershed #1 (Wetland Area) 1.29 1.05 Watershed #2 (Development Area) 1.17 0.00 For HydroCAD modeling analysis of the stormwater systems, the following methods and assumptions were used:  Simple Dynamic  Rawls Rate of 8.27 in/hr for sands within the subsoil layers for subsurface leaching galleys.  Rawls Rate of 2.41 in/hr for the loamy sands in the upper soil layers for dry water quality swales.  Volume capacity of dry water quality swales excluded from peak discharge and recharge calculations.  Exfiltration has been assumed to occur along wetted surface area of bottom and walls/slopes. Erosion Control Plan - Temporary Siltation Barrier & Silt Socks: The property currently provides 9-inch straw wattles for erosion and sediment controls. The locations of the straw wattles follow the limit of work line as shown on the plan view. The Contractor has been monitoring the limit of work line for breakthrough, while construction is ongoing. The site is well graded and appears to be stable, given the length of time the site has been a construction site. The following applies to new excavation and grading as outline on the Stormwater Plan.  The erosion controls shall include a row of staked 9-inch straw wattles surrounding the proposed excavation for the leaching galleys.  Once the swales are constructed and graded, the swales shall be protected from washout or siltation until the grass is established. Contractor shall use the wattles or erosion control blankets as necessary to protect the swale.  The erosion controls shall be monitored and corrected during the entire construction phase and until the site has been stabilized with ground cover and the proposed landscape.  Contractor shall be required to provide extra siltation controls in case a repair is needed to the straw wattles and/or catch basin filter fabric. Operation and maintenance plan is included herewith to address the long-term maintenance of the stormwater systems. Page 6 of 10 178 BONNIE DOONE CARTWAY LLC STORMWATER MANAGEMENT REPORT BONNIE DOONE CARTWAY, BREWSTER, MA MAY 17, 2023 JMO-8705 Massachusetts Stormwater Management Design Standards: The following is a description of how the proposed project meets the Massachusetts Stormwater Handbook design standards. Standard 1: No new untreated discharges: This standard is met since there are no new untreated stormwater discharges proposed. See Standards 4- 6 calculations. Standard 2: Maintain Pre-development peak discharge rate: This standard has been met. Refer to the Table above. Groundwater Recharge: This standard is met. The proposed stormwater management systems are sized so that the total recharge volume provided exceeds the minimum groundwater recharge volume specified in the handbook and the proposed stormwater recharge galleys will drawdown within 72 hours of a storm event. In accordance with the MA Stormwater Manual, the required recharge volume factor (F) required across the impervious area (A) is 0.6 inches per hour for hydraulic soil group A soils. Fine Sand (Rawls Rate: 8.27 inches per hour) has been used in the sizing of the stormwater recharge galleys. Refer to the HydroCAD Stormwater Modeling Report in Appendix. The required recharge volume is calculated based on the total pavement and roof areas on site.  Required Recharge Volume Rv = F x A = (0.6 in)(1 ft/12 in)(24276 sf) = 1,214 cf (Roof & Driveway)  Recharge Storage Provided (Subsurface leaching facilities for roof and Swale) = 2,850 cf > 390.0 cf  The drawdown for the subsurface leaching facilities for the driveway/parking system and roof runoff is 12.0+/- hours < 72 hour maximum allowance. Standard 4: Water Quality: This standard has been met. The roof runoff stormwater system will remove 80% of the annual load of Total Suspended Solids (TSS) via subsurface leaching facilities. The main stormwater system serving the driveway and the remaining altered areas of the parcel provides 91% TSS pretreatment removal of driveway. TSS removal calculation tables for driveway and altered portions included in the Appendix A. The calculations have been set up to utilize the fire lane looped swale and then the larger natural swale. Phosphorus (P) reductions are estimated based on the pre-treatment dry swale and the overland disposal of the stormwater within the natural low point/swale. Our office estimates a 60% reduction in both nitrogen and phosphorus when utilizing the two dry swales and the large natural low point/ swale, as noted. Three swales at 20% each, provides the 60 % provision within the Brewster By-law. In accordance with the MA Stormwater Manual, the required water quality depth (Dwq) across the impervious area (A) is 1.0 inches per hour in areas containing soils with rapid infiltration rate greater than 2.4 in/hr. The required water quality volume is based on the total pavement area on site. Page 7 of 10 178 BONNIE DOONE CARTWAY LLC STORMWATER MANAGEMENT REPORT BONNIE DOONE CARTWAY, BREWSTER, MA MAY 17, 2023 JMO-8705  Required Water Quality Volume Vwq = Dwq x A = (1.0 in)(1 ft/12 in)(19,000 sf) = 1583 cf (gravel driveway)  Water Quality Storage Provided (natural low point / swale) = 4,998 cf > 315 cf Standard 5: Land uses with higher potential pollutant loads: This standard has been met. The proposed use is a residential building. Standard 6: Stormwater discharges within Zone II or Interim Wellhead protection area of a public water supply and stormwater discharges near or to any critical area. This standard has been met. Not Applicable as the site is not in a Zone 2 for a Drinking Water Well. The 1/2 inch Required Water Quality Volume for discharges within a Groundwater Protection area has been met, see Standard 4 calculations. Standard 7: Redevelopment: This standard is not applicable given the new development. Note, the a portion of the parcel is developed, however, the portion of the majority of work is not developed so we have looked at this site a new development. Standard 8: Construction Erosion Control Plan: The project is subject to the proposed erosion control plan as outlined on the plan. Straw wattles shall be implemented as required to mitigate erosion of soil. Standard 9: Long Term Operation and Maintenance Plan: A long-term O&M plan has been submitted with this report, refer to Appendix. The property owners will operate and maintain the stormwater systems. Standard 10: Illicit Discharges: This standard is met since there are no illicit discharges at this site and no illicit discharges proposed. Page 8 of 10 178 BONNIE DOONE CARTWAY LLC STORMWATER MANAGEMENT REPORT BONNIE DOONE CARTWAY, BREWSTER, MA MAY 17, 2023 JMO-8705 Owner and Responsible Party The owner and responsible party for Stormwater Pollution Control at 178 Bonnie Doone Cartway, Brewster, MA Owner & Operator: 178 Bonnie Doone Cartway, LLC 8 Lot Phillips Lane Norwell, MA 02061 Schedule of Inspection and Maintenance of Stormwater Management Systems 1. All stormwater systems require regular attention to ensure the effectiveness of the systems. It is recommended that the drainage systems be inspected annually by a stormwater operation and maintenance professional to ensure that the system is properly maintained. Any deterioration threatening the structural integrity of the system shall immediately be repaired. 2. Gravel areas shall be inspected to remove debris and good housekeeping measures should be implemented throughout the site in order to keep gravel areas, gutters, downspouts, drain lines and grassed swales clean of debris. 3. All subsurface leaching facilities shall be inspected at least twice a year. Any debris that may clog the system must be removed. 4. The grassed swales shall be inspected and mowed as needed to prevent excessive growth under control. Inspect the grass side slopes and bottom for signs of erosion and formation of gullies. The swales should be mowed 1 to 2 times a year, depending on growth. Remove accumulated trash, debris and silt as needed and at time of inspection. Estimate of annual operation and maintenance budget for common areas = $ 2,500.00 Long Term Lawn Care & Pollution Prevention Plan Description of Pollutant Sources:  Light vehicle traffic – residential development  Lawn care products Source Control Best Management Practices  There shall be no storage of items or materials which will be subject to the weather.  Good housekeeping measures shall be implemented throughout the site to keep the driveways clean of debris.  Regularly cleaning the gravel areas to remove debris and any other potential stormwater pollutants.  The use of winter de-icing sand and salt materials shall be minimized to the maximum extent practicable.  Winter de-icing sand and salt materials shall be stored indoors.  Snow storage shall not be within the swales. Page 9 of 10 178 BONNIE DOONE CARTWAY LLC STORMWATER MANAGEMENT REPORT BONNIE DOONE CARTWAY, BREWSTER, MA MAY 17, 2023 JMO-8705  Immediately clean up any spillage on gravel areas and dispose of wastes properly. Emergency Spill Cleanup Plan 1. The owner of the facility shall have a designated person with overall responsibility for spill response cleanup. 2. In the event of a spill the following shall be notified: A. Brewster Fire Department (508) 896-1708 (for a gasoline or hazardous material spill) 911 B. Massachusetts D.E.P. Emergency Response (800) 304-1133 C. Brewster Health Department (508) 896-3701 ext. 1120 3. Cleanup of spills shall begin immediately. Page 10 of 10 178 BONNIE DOONE CARTWAY LLC STORMWATER MANAGEMENT REPORT BONNIE DOONE CARTWAY, BREWSTER, MA MAY 17, 2023 JMO-8705 O&M Log Form Condition Inspector Initials Item Inspected Date Time Good Clean-out Needed Repair Needed Repaired Date O&M Log form records to be maintained by property manager for a minimum of three years Ernst Conservation Seeds 8884 Mercer Pike Meadville, PA 16335 (800) 873-3321 Fax (814) 336-5191 www.ernstseed.com Date: May 22, 2023 Native Detention Area Mix - ERNMX-183 Botanical Name Common Name Price/Lb 26.00 %Panicum clandestinum, Tioga Deertongue, Tioga 22.50 25.00 %Panicum virgatum, 'Carthage', NC Ecotype Switchgrass, 'Carthage', NC Ecotype 13.17 20.00 %Carex vulpinoidea, PA Ecotype Fox Sedge, PA Ecotype 28.80 20.00 %Elymus virginicus, Madison-NY Ecotype Virginia Wildrye, Madison-NY Ecotype 10.35 4.00 %Agrostis perennans, Albany Pine Bush-NY Ecotype Autumn Bentgrass, Albany Pine Bush-NY Ecotype 16.80 3.00 %Juncus effusus Soft Rush 48.00 1.00 %Juncus tenuis, PA Ecotype Path Rush, PA Ecotype 48.00 1.00 %Panicum rigidulum, PA Ecotype Redtop Panicgrass, PA Ecotype 57.60 100.00 %Mix Price/Lb Bulk:$20.14 Seeding Rate:20 lb per acre, or 1/2 lb per 1,000 sq ft. For a cover crop: grain rye (1 Sep to 30 Apr; 30 lbs/acre), Japanese millet (1 May to 31 Aug; 10 lbs/acre). Grasses & Grass-like Species - Herbaceous Perennial; Stormwater Management The native grasses, sedges and rushes establish quickly in areas where mowing is not anticipated. With a high seed count per pound, it can achieve native establishment with minimum risk and tolerate low-fertility. Mix formulations are subject to change without notice depending on the availability of existing and new products. While the formula may change, the guiding philosophy and function of the mix will not. Price quotes guaranteed for 30 days. All prices are FOB Meadville, PA. Please check our web site at www.ernstseed.com for current pricing when placing orders. MODIFICATION OF MAJOR STORMWATER MANAGEMENT PERMIT CASE NO. 2023-12 APPLICANT/OWNER: CHRISTOPHER AND GILLIAN PLATTS PROPERTY: 0 RUN HILL ROAD 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: Modification to Major Stormwater Permit SWMP23-12 Run Hill Road (Map 35 Parcel 32) Applicant, M/M Platts c/o JM O’Reilly & Associates, Inc. DATE: May 31, 2023 ______________________________________________________________________________ Recommendation Approve the requested modification to the previously granted Major Stormwater Permit. As modified, the site stormwater management system continues to meet the applicable performance standards set out in the town’s Stormwater Management Regulations. Discussion The Stormwater Management Regulations require permit Modification for any ‘significant’ change associated with a previously granted Major Permit (See Section 5.8). The Planning Board voted to approve the above-referenced permit, with conditions, at its meeting on 4/12/23. The written permit issued on 4/24/23. There was some cursory discussion at the 4/12/23 meeting about whether the applicant could use an existing natural depression on the site as part of the system, to infiltrate site run-off (rather than to use and install manufactured subsurface leaching facilities). At that time, the applicant was unsure whether use of the natural depression was viable and how this approach might affect the neighboring property to the west because the site feature straddles the common property line. The Regulations encourage the use of LID (Low Impact Development) type stormwater facilities, like existing natural features of a site, to the maximum extent practicable. The applicant has now applied to use the referenced natural depression in the northwest portion of the site as part of the stormwater system, determining that it would be viable and effective. The applicant has also obtained and provided a copy of written consent by the neighbor to this arrangement. This would allow the two proposed subsurface leaching galleys from the original design, connected to the grass swales, to be eliminated. As proposed, run-off from the driveway would still be collected by proposed grass swales; however, any overflow that does not infiltrate in the swales would be directed to the natural depression for infiltration. Run-off from the site (and to some degree Run Hill Road) is currently collected and infiltrated in this natural low point. The Applicant has provided sufficient application materials to support the modification, including a site plan (revised 5/28/23) and revised HydroCad sheets (dated 5/29/23). As proposed to be modified, the site stormwater management approach meets the applicable performance standards in the Regulations, including as relate to post-development run-off and recharge rates, and water quality treatment. The foregoing describes the extent of the proposed changes. The permit and stormwater system would remain as previously approved, except as may be expressly modified by the Board. Office of: Planning Board Planning Dept. Paul M. Alt 140 Run Hill Rd Brewster, MA 02631 April 13, 2023 RE: Storm water drainage To: Chris Pla%s Chris, this le%er is a confirma(on of the discussion we had yesterday about storm water drainage from your new property. I have no objec(on to the proposal of allowing the depression at the road end of our proper(es to serve as a natural run off collec(on area for your property. The assump(on here is that the water load post construc(on will be comparable to its historic values. Regards, Paul MAJOR STORMWATER MANAGEMENT PERMIT CASE NO. 2023-21 APPLICANT/OWNER: JANICE MARINELLO PROPERTY: 439 PAINES CREEK ROAD 439 Paines Creek Road SWMP23-21 Staff Report Page 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 SWMP23-21 439 Paines Creek Road (Map 38 Parcel 1) Applicant, Janice Marinello c/o Matthew Farrell, EIT, J.M. O’Reilly & Associates, Inc. DATE: May 23, 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 single-family residential property with a new residence, detached accessory building with ADU, swimming pool, a new gravel driveway and other supporting improvements. The property is not located in the DCPC overlay district/ Zone II or a flood zone, and is not affected by wetlands. The site is relatively flat. Major Stormwater Permits are subject to review at a public meeting, including for any waivers requested. This project triggers a Stormwater Permit under Chapter 272 of the Brewster Code (Stormwater Management Bylaw) and according to Section 4 of the Bylaw’s supporting regulations, a Major Stormwater Permit is required because the project involves net new impervious surface of 2500 sq ft or greater. The Planning Board is the Stormwater Permitting Authority because the proposed development is located outside wetlands jurisdiction. The Applicant has provided the required application materials for a Major Stormwater Permit, including a site plan set (dated 5/18/23) and Stormwater Management Report with HydroCad analysis (revised dated 5/15/23), as set out in Appendix B of the Stormwater Management Regulations. No waivers from the Bylaw/ Regulations have been requested or identified as necessary. The site stormwater system consists of two grassed swales, an infiltration trench and a three-chamber subsurface leaching facility.  The grass swale in the “front” (east) yard will collect and treat run-off from the east and north portions of the site (including the driveway) and convey it to the subsurface leaching facility located in the “rear” (west) yard;  The building roof run-off will be separately collected from the site run-off and piped directly to the subsurface leaching facility; Office of: Planning Board Planning Dept. 439 Paines Creek Road SWMP23-21 Staff Report Page 2  The pool run-off will be directed to an infiltration trench with overflow piped to the subsurface leaching facility;  The grass swale in the “rear” (west) yard will collect and treat run-off from the west and south portions of the site and convey it to the subsurface leaching facility. The Stormwater Management approach meets the applicable standards in relevant Sections 6.1B and 6.2B of Brewster’s Stormwater Regulations, including consistency with the State Stormwater Handbook standards:  The system was designed under post-development conditions to maintain stormwater recharge capacity on-site for the 2, 10, 25 and 100-year storm events;  As designed, post-development runoff rates are reduced to less than the pre-development conditions including for the 100-year storm;  The Applicant has provided an Operations and Maintenance Manual that sets out proper, long- term procedures to maintain the proposed post-construction BMPs;  The Applicant has provided an appropriate construction-period erosion and sedimentation control plan;  The site stormwater approach incorporates Low Impact Development-type (LID) stormwater design elements;  The site system provides the required TSS and Phosphorus treatment, including through pre- treatment and “first flush” water quality volume retention;  The Applicant’s soil tests on the property, and NRCS mapping, have revealed sandy and well- draining soils.  There is sufficient vertical separation between the stormwater facilities and groundwater to allow proper system function. APPROVAL NOT REQUIRED, CASE NO. 2023-05 APPLICANT/OWNER: ELDREDGE FAMILY TRUST, SUSAN ELDREDGE, TRUSTEE AND MICHAEL AND STEPHANY HUTCHINSON PROPERTY: 0, 26, AND 96 MAURY LANE Date: May 26, 2023 To: Planning Board From: Jon Idman, Town Planner Re: PB#2023-05, Approval Not Required Plan Endorsement Owner/ Applicant: Susan Eldredge Trustee, Eldredge Family Trust & Michael & Stephany Hutchinson Property: 0, 26 & 96 Maury Lane (Tax Assessors Map/ Parcel Nos. 56/60, 56/59, 56/93) _____________________________________________________________________________________ Staff Recommendation/ Motion In Case No. PB#2023-05, Vote to endorse the plan entitled “Plan of Land, Maury Lane, Brewster MA, Being a Division of Lot 3 as Shown in Plan Book 554 Page 44 & a Redivision of Lot 1B and Lot 1C and Lot 2 as Shown in Plan Book 554 Page 45,” prepared and stamped by Timothy J. Brady, PLS, East Cape Engineering, Inc., dated 4/28/23, as it does not depict a subdivision and thus does not require approval under the subdivision control law. Discussion Owner/ applicant has submitted a plan of land to the Board for endorsement which shows a re-division of four existing lots/ parcels of record. The purpose of the division is to create one additional building lot. The plan 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 applicant maintains that no subdivision approval is required for the division because the plan does not depict a ‘subdivision’ as defined under the subdivision control law. In the case at hand, the proposed land division is not a subdivision so-defined and an ANR endorsement is warranted because all proposed building lots affected have the minimum frontage on Maury Lane required under the Brewster Zoning Bylaw for the applicable RM district. Maury Lane is a way approved under the subdivision control law (note, in its subdivision approval the Brewster Planning Board did not require that Maury Lane be brought up to the full road construction standards; an existing access drive pre-dated the subdivision road layout) The existing travelled way currently provides adequate access to the subject land, some of which is developed with residential buildings and supporting improvements. The plan will also help facilitate an intrafamily transfer- the party applicants are related. Though the proposed building lots appear to meet all minimum dimensional requirements for residential building lots and do not otherwise create or intensify any nonconformities under the Brewster Zoning Bylaw, the Board’s endorsement does not itself imply zoning compliance (other than as to frontage) or represent the buildability of the lots; these zoning issues are beyond the scope and authority of the Board under a request for ANR endorsement. Town Of Brewster 2198 Main Street Brewster, Massachusetts 02631-1898 (508) 896-3701 x1150 Office of: Planning Department TIMELINE FOR WORK ON THE ADU SECTION OF THE ZONING BYLAW ADU ZONING AMENDMENT TIMELINE 2023 & PLANNING BOARD REGULAR MEETING DATES JUNE JULY AUGUST SEPT OCT NOV 6/14 6/28 7/12 7/26 8/9 8/23 9/13 9/27 10/11 10/25 11/8 PB WORKPLAN DISCUSSION LISTENING SESSION/S Outreach to related committees (e.g. ZBA and Housing Partnership) & community organizations DRAFTING WORKSHOPS/ PB VOTE Hrg notice to newspaper (3 weeks advance) |------------------MGL C. 40A s. 5 Procedures-----------------| PB submission to SB SB referral to PB Hrg Notice published (14/7 days in advance) Public Hearing/s PB Vote/ Recommendation SB Vote/ STM Warrant Closes (est. 10/13) STM 11/13 PB Report |----------------------------------INPUT: PUBLIC, STAFF, COMMITTEES, OFFICIALS -------------------------------------| DRAFT MEETING MINUTES DATED MAY 24, 2023 PB Minutes 05/24/23 Page 1 of 4 Brewster Planning Board 2198 Main Street Brewster, MA 02631-1898 (508) 896-3701 x1133 brewplan@brewster-ma.gov MEETING MINUTES Wednesday, May 24, 2023 at 6:30 pm Brewster Town Office Building Chair Madalyn Hillis-Dineen convened a meeting of the Planning Board at 6:30 pm with the following members participating: Amanda Bebrin, Tony Freitas, Rob Michaels, Elizabeth Taylor, and Alex Wentworth. Charlotte Degen was not present. Also participating: Jon Idman, Town Planner, and Lynn St. Cyr, Senior Department Assistant. Hillis-Dineen declared that a quorum of the Planning Board was present. She read the Meeting Participation Statement and Recording Statement. 6:32 PM CITIZEN’S FORUM No citizen comments. 6:33 PM REORGANIZATION OF PLANNING BOARD Hillis-Dineen asked for nominations for Planning Board Chair. Motion by Wentworth to Nominate Bebrin as Chair of the Planning Board. Second by Michaels. Bebrin accepted the nomination. Vote: 6-0-0. Bebrin took over the meeting as Chair. Bebrin asked for nominations for Planning Board Vice Chair. Motion by Bebrin to Nominate Wentworth as Vice Chair of the Planning Board. Second by Michaels. Wentworth accepted the nomination. Vote: 6-0-0. Bebrin asked for nominations for Planning Board Clerk. Motion by Wentworth to Nominate Michaels as Clerk of the Planning Board. Second by Freitas. Michaels accepted the nomination. Vote: 6-0-0. Bebrin asked for nominations for a member to recommend to the Select Board for appointment to the Brewster Affordable Housing Trust. Motion by Hillis-Dineen to Nominate Tony Freitas as the Planning Board Member Recommended to the Select Board for Appointment to the Brewster Affordable Housing Trust. Second by Michaels. Freitas accepted the nomination. Vote: 6-0-0. 6:35 PM PUBLIC MEETING Continued review and discussion on the accessory single-family dwelling unit and accessory commercial dwelling unit sections of the zoning bylaw. Documents:  04/27/23 Memo re: ADU provisions from Jon Idman, Town Planner  04/27/23 Memo re: ACDU provisions from Jon Idman, Town Planner  Brewster’s Experience: ADU, ACDU, & Accessory Apartments since 2018 Bylaw and spreadsheet  Sections of Zoning Bylaw-179-2 (Definitions); 179-42.2 (ADUs); 179-42.3 (ACDUs); 179-25 (Extensions and Alterations); 179-26 (Residential lots of record); Table 1 (Use regulations); and Table 2 (Area regulations) Assistant Town Manager Donna Kalinick was present and participated in the discussion. Idman started the discussion by providing the Planning Board with a summary of the accessory commercial dwelling unit (ACDU) section of the zoning bylaw. He noted that a larger discussion including multi-family and mixed-use development would be beneficial. For purposes of zoning amendments, he recommended the Planning Board focus their current efforts on accessory dwelling units (ADUs). He referred the Planning Board to the ACDU memo he prepared. Idman noted that Table 1 (Use Approved: Vote: PB Minutes 05/24/23 Page 2 of 4 regulations) of the zoning bylaw does not specifically allow ACDUs in the Industrial zoning district, however Table 2 (Area regulations) suggests in a footnote that ACDUs can be developed in the Industrial district. Idman stated that this may be something the Planning Board would look to fix through amendments. Based on his research, he does not believe it was intended to allow ACDUs in the Industrial district. Wentworth asked why ACDUs would not be allowed in the Industrial district. Idman responded that residential uses sometimes conflict with Industrial uses. Idman further stated that security dwellings may be allowed in Industrial areas to safeguard businesses and activities of businesses. Michaels asked for clarification on security dwellings. Idman responded that security dwellings have been in the zoning bylaw for years and their purpose is to safeguard the business and to oversee the activities of businesses. One security dwelling is allowed per property. Idman stated that the bylaw is unclear on how many ACDUs are allowed on a site, but it appears the intent is to allow more than one per site. Idman mentioned a grant request he is working on with Town Administration for funds that would be used for a more comprehensive review of the zoning bylaw as it relates to commercial dwellings. The Planning Board agreed to table discussions on ACDUs for the time being to focus on ADUs for potential amendments at Fall Town Meeting. Idman stated that the Planning Board could make a technical correction to the ACDU section of the bylaw by clarifying whether ACDUs are allowed in the Industrial district. Jillian Douglass addressed the Planning Board. She stated that she was previously part of a review committee that included the Housing Partnership and the Affordable Housing Committee. They did not have the authority to change bylaws, but they did review residential uses and decided that accessory dwelling units or affordable accessory apartments as they were known at the time were not suited for Commercial and Industrial districts due to the potential occupants having children. Douglass agreed that there was a larger discussion to have on mixed-use properties and that consideration of children should be included in that discussion. The Planning Board continued their discussion on ADUs. Idman requested that the Planning Board provide directions as to what they would like to see as next steps. Freitas asked if it made sense to form a subcommittee to focus on the ADU bylaw that could handle research needed and come up with a work plan. Bebrin stated that the Planning Board could decide to form a subcommittee and that the committee could be tasked with coming up with a recommended list for changes to the ADU bylaw. Idman suggested that he could provide the Select Board with the ADU memo the Planning Board has reviewed as a starting point to communicate to the Select Board that the Planning Board is considering amendments to the ADU section of the bylaw. Idman suggested the Planning Board consider their work plan. He stated that since the Planning Board meets twice a month one meeting per month could be a planning meeting and the other meeting could be regulatory, subject to regulatory deadlines. Bebrin noted the importance of public engagement as the Planning Board works on the ADU bylaw. Kalinick stated that since 2018 when the first ADU bylaw was worked on the town has been very intentional with handling all housing related work in the public realm as discussions and work within housing can be difficult. The Housing Partnership was very involved in work on the first ADU bylaw including bringing it to the Planning Board and helping with public outreach. The Housing Partnership does have an interest in playing a role in any amendments to the ADU bylaw. Kalinick stated that the town is in a different place now than it was when the ADU bylaw was originally drafted. There is a general understanding that ADUs have not ruined the character of Brewster and that they can be an important tool in creating more housing units. Kalinick mentioned that she’s been at recent regional meetings and ADUs have been a topic of discussion including making them easier for people to use including easing permitting, looking at modular units, and financing options with local banks. Idman stated that the work of a subcommittee would be conducted in public as well and meetings would be noticed and posted. Michaels stated that he believes that the Planning Board is still in the phase of generating ideas and the public forum may be beneficial to obtain ideas. Idman stated that the Planning Board’s first step could be to have a public listening session. Bebrin stated that her preference would be to have the full board consider the ADU bylaw during regular meetings or special meetings if needed. Wentworth stated it would be interesting to get the public’s feedback on how ADUs should be regulated for year-round rentals. PB Minutes 05/24/23 Page 3 of 4 Fran Manion, Lower Road, stated that she is currently working on a detached ADU. The ADU process for her has taken two years thus far and a tremendous amount of research. Manion stated that a lot of survey work has been done on her property and it has been costly. She also had to hire an architect. She is very sensitive to the environment and although a new septic system is not needed, she is willing to put in a new system. Manion stated that due to the expense, ADUs are not an option for those with moderate incomes. Manion stated that she thinks Brewster is doing a good job with affordable housing. Unfortunately, developers get preferential treatment and make money developing affordable housing whereas the moderate-income individual gets no breaks. Low-income units are great, but Manion urged the Planning Board not to forget those that fall in between low and high income. Manion urged the Planning Board not to delay work on ADUs and to take a leadership role. Steve Najarian, 571 Stony Brook Road, is also planning for an ADU on his property. Najarian stated that he is a landlord in Boston and noted the importance of life safety issues and creating more opportunities for ADUs to reduce illegal, unsafe units. He expressed concern with the requirement of the sworn affidavit stating that the unit will be rented for 12 months. He stated that renters may move and may not actually stay a full 12 months. He recommended making the affidavit requirement more flexible. Najarian discussed the registration system for units he rents in Boston which includes arbitrary inspections by the city. He also mentioned that the Building Inspector has some flexibility in working with the Building Code as it relates to the construction of ADUs. Najarian stated that the ADU process including surveying work has been expensive so it will be hard to make the unit affordable, but he will charge a reasonable rent. Jillian Douglass asked the Planning Board to stay open to all the comments they receive as people have unique situations. Douglass stated that occupancy year-round on the property was a goal of the original bylaw and there was a component to encourage keeping locals. She stated that the Housing Partnership is also interested in being part of this process. Hillis-Dineen appreciated the comments made by Fran Manion and believes there needs to be work done to make ADUs more affordable. She stated that she agrees with Freitas that an ad hoc committee to work on the ADU bylaw and report back to the Planning Board with concrete amendments may be a good idea. The Planning Board discussed next steps in the ADU process including communicating to the Select Board their intent to work on the ADU section of the zoning bylaw and conducting structured listening sessions with members of the public. Motion by Michaels to Direct the Town Planner to Communicate to the Select Board the Planning Board’s Intention to Review and Potentially Amend the Accessory Dwelling Unit Section of the Zoning Bylaw. Second by Hillis-Dineen. Vote: 6-0-0. Idman suggested further research could be done as needed to not delay the process. Freitas stated that he does not want to see the process delayed by research but does want the Planning Board to be able to come up with a bylaw that works for people. Bebrin stated that the bylaw should include a statement that speaks to the bylaw’s intent to create year-round housing. Bebrin thinks the Planning Board will benefit from public listening sessions which will help the Board understand what barriers the public is facing and how to reduce those barriers. The goal is to make the bylaw more functional. Idman stated that he would like to discuss a work plan with the Planning Board at their next meeting including how best to structure a listening session. Freitas expressed concern that it may be difficult to engage residents during the summer months. Michaels stated that the Brewster population triples during the summer so there may be more people willing to give feedback. Fran Manion suggested the Planning Board reach out to the Housing Assistance Corporation as they have educational materials that may be helpful with communicating to the public. Taylor requested a timeline for the Planning Board’s work on the ADU section of the bylaw. Michaels stated that the Planning Board needed to think long term as well and suggested it was possible that zoning amendments may be on the town meeting warrant every year. Jillian Douglass stated that the process is progressive and the Planning Board should continue to work on ADU amendments. Idman stated a work plan including a timeline in anticipation of Fall Town Meeting will be provided at the next Planning Board meeting. PB Minutes 05/24/23 Page 4 of 4 7:26 PM APPROVAL OF MEETING MINUTES Approval of Meeting Minutes: May 10, 2023. The Board reviewed the May 10, 2023 meeting minutes. Motion by Wentworth to Approve May 10, 2023 Meeting Minutes. Second by Michaels. Vote: 6-0-0. 7:27 PM COMMITTEE REPORTS Michaels announced that the Water Quality Review Committee would be meeting on Friday, May 26, 2023. Wentworth stated that the Vision Planning Committee continues to work on editing the Local Comprehensive Plan and their next meeting is scheduled for Monday, June 5, 2023. Bebrin stated that the Bay Property Planning Committee held the first public forum at the bay property and it was well attended. The consultants are reviewing the information gathered and are expected to share results in about a month. A survey regarding long term planning for the Sea Camps properties will be available to Brewster residents beginning Thursday, May 25, 2023. Kalinick thanked Hillis-Dineen for her work on the Brewster Affordable Housing Trust (BAHT). She has been a member of the BAHT since its inception. Hillis-Dineen’s term with BAHT ends on June 30, 2023 and she has decided not to seek reappointment. 7:30 PM FOR YOUR INFORMATION The Planning Board received a notice from the Harwich Planning Board regarding a public hearing scheduled for Tuesday, June 13, 2023. Griffin Ryder, DPW Director, will be participating in the Planning Board’s June 28th meeting to discuss stormwater management. Motion by Wentworth to Adjourn. Second by Michaels. Vote: 6-0-0. The meeting adjourned at 7:35 PM. Next Planning Board Meeting Date: June 14, 2023. Respectfully submitted, __________________________________________ Lynn St. Cyr, Senior Department Assistant, Planning FOR YOUR INFORMATION