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HomeMy WebLinkAbout25SITE2 - Drainage ReportFULLER ENGINEERING & LAND SURVEYING, LLC 525 John Street · Second Floor Bridgeport, CT 06604 (203) 333-9465 (203) 336-1769 FAX FULLER ENGINEERING & LAND SURVEYING, LLC 525 JOHN STREET 2ND FLOOR BRIDGEPORT, CONNECTICUT 06604 PHONE (203)333-9465; FAX (203)336-1769 ENGINEERING REPORT Project Name: Madison Place Luxury Townhouse Development 18 Powerhouse Road & 145 CT Route 32 Montville, CT Information prepared for: JNE Holdings, LLC & Town of Montville Department of Public Works / Engineering Department Dated: January 11 February 2025 TABLE OF CONTENTS (Stormwater Study) PHASE 1 Introduction 1 Narrative 1 Pre-Development Conditions 1 Proposed Post Development Conditions 2 Calculations 2 Summary 3 Conclusion 3 PHASE 2 Narrative 4 Pre-Development Conditions 4 Proposed Conditions 4 Calculations 4 Summary 5 Conclusions 5 Soil Erosion and Sedimentation Control (All Phases) 6 Montville Precipitation Frequency (PF) Rainfall Data Appendix A NRCS Soil Map & Hydrologic Soil Group Rating Appendix B HydroCAD Analysis - PHASE 1 Appendix C HydroCAD Analysis - PHASE 2 Appendix D Operations and Maintenance Plan Appendix E FULLER ENGINEERING & LAND SURVEYING, LLC 525 John Street – Second Floor – Bridgeport, CT 06604 Phone: (203) 333-9465 Fax: (203) 336-1769 FULLER ENGINEERING & LAND SURVEYING, LLC 525 JOHN STREET 2ND FLOOR BRIDGEPORT, CONNECTICUT 06604 PHONE (203)333-9465; FAX (203)336-1769 P a g e | 1 STORMWATER STUDY APPLICANT: JNE HOLDINGS, LLC PROJECT LOCATION: WILTONS WAY 18 Powerhouse Road & 145 Route 32, Montville, Connecticut INTRODUCTION The proposed project consists of the merger of two parcels into one lot consisting of 110,146 S.F.: 145 CT Route 23 Site Area: 59,415 S.F. One existing 4 family residential unit. 18 Powerhouse Road Site Area 50,731 S.F. One existing 2 family residential unit. The proposed project is anticipated to be constructed in three phases. The drainage computations for this project are separated into two groups; Drainage Study 1 (Phase 1 sitework); Drainage Study 2 (Phase 2 and 3 sitework.) DRAINAGE STUDY Phase 1 NARRATIVE The subject of this report is a 1.337-(disturbed area) acre portion of a parcel located at 145 Route 32 in Montville, constituting Phase 1 of the proposed project. The purpose of this report is to determine the existing and proposed runoffs resulting from the proposed site improvements in order to design a stormwater management system. PRE-DEVELOPMENT CONDITIONS The subject parcel is located on the west side of Route 32, at its intersection with Powerhouse Road. The lot currently contains buildings and a driveway. The lot slopes moderately to steeply across its width, generally from the west to the east. Existing soils at this location, as identified in the NRCS Soil Survey of Fairfield County, Connecticut, consist of Narragansett silt loam, 2 to 8 percent slopes, which has a Hydrologic classification of “B”. Stormwater Study –Madision Place 11 February 2025 JNE Holdings, LLC 18 Powerhouse & 145 Route 32 Montville, CT P a g e | 2 FULLER ENGINEERING & LAND SURVEYING, LLC 525 JOHN STREET 2ND FLOOR BRIDGEPORT, CONNECTICUT 06604 PHONE (203)333-9465; FAX (203)336-1769 The existing runoff from a 50-Year rainfall event is 5.92 c.f.s. PROPOSED POST-DEVELOPMENT CONDITIONS The proposal for this phase is to construct 3 residential units (two additional units with renovations to the existing house on Powerhouse Road), with associated driveway, site utilities, and miscellaneous site improvements. The proposed runoff (prior to mitigation) from a 50-Year rainfall event is 6.88 c.f.s. CALCULATIONS The following computations of the existing and proposed conditions runoff flows were derived from the HydroCAD computer software. HydroCAD follows the NRCS TR-20 procedure for computing stormwater runoff. Computations were performed for a 50-year storm event, which has a 2% chance of occurring in any given 12-month period. Existing Conditions (Phase 1): Buildings 1,072 s.f. CN 98 Driveway 1,107 s.f. CN 98 Concrete slab 243 s.f. CN 98 Lawn 55,821 s.f. CN 69 Total 58,243 s.f. Weighted CN - 70 Proposed Conditions (Phase 1): Building 4,741 s.f. CN 98 Driveway/Parking 9,018 s.f. CN 98 Lawn 44,484 s.f. CN 69 Total 58,243 s.f. Weighted CN - 76 Groundwater Recharge Volume (GWV): Impervious area = 23.6 % WQV = (0.2624 * 1.337 ac)/12 x 1.3 = 0.03800645 ac-ft = 1,655.6 ft3 GWV = 1,655.6 * 0.25 = 413.9 ft3 Stormwater Study –Madision Place 11 February 2025 JNE Holdings, LLC 18 Powerhouse & 145 Route 32 Montville, CT P a g e | 3 FULLER ENGINEERING & LAND SURVEYING, LLC 525 JOHN STREET 2ND FLOOR BRIDGEPORT, CONNECTICUT 06604 PHONE (203)333-9465; FAX (203)336-1769 SUMMARY: 50 Year 25Yr. 10Yr. 5Yr. 2Yr. Existing Runoff : 5.92 c.f.s 4.81 3.42 2.47 1.42 Proposed Runoff : 6.88 c.f.s 5.72 4.24 3.21 2.03 Runoff Retained: 1.54 c.f.s. 1.36 1.11 0.94 0.73 Areas Bypassing Retention Plus overflow: 5.28c.f.s. 4.32 3.12 2.29 1.36 CONCLUSION The increased runoff resulting from the proposed site improvements will be retained in an on- site retention system. The runoff from the driveway will be routed to 192 linear feet of 48” concrete galleries. The increase in stormwater runoff is mitigated on-site. This system will reduce the net peak run-off during a 50 Year (2%) rainfall event to 5.28 c.f.s. from its current peak of 5.92 c.f.s. The bottom of the concrete galleries will be at elevation 97.0. No restrictive layer was found to an elevation of 96.0. The proposed retention system provides a total of 3,131 ft3 of storage, which will be adequate to maintain the net runoff during a 50 Year rainfall event, meets the Water Quality Volume and will provide groundwater recharge. The maximum peak net runoff from the proposed conditions decrease compared to the peak runoff from the existing conditions for each of the rainfall events from the 2 Year to the 50 Year rainfall events, as the table above illustrates. The proposed improvements will have no adverse impact on surrounding properties. Stormwater Study –Madision Place 11 February 2025 JNE Holdings, LLC 18 Powerhouse & 145 Route 32 Montville, CT P a g e | 4 FULLER ENGINEERING & LAND SURVEYING, LLC 525 JOHN STREET 2ND FLOOR BRIDGEPORT, CONNECTICUT 06604 PHONE (203)333-9465; FAX (203)336-1769 STORMWATER STUDY Phases 2 and 3 NARRATIVE: The subject of this report is a 1.185 acre portion (Disturbed Area of Phases 2 and 3) of a parcel located at 145 Route 32 in Montville, constituting Phases 2 and 3 of the proposed project. The purpose of this report is to determine the existing and proposed runoffs resulting from the proposed site improvements in order to design a stormwater management system. PRE-DEVELOPMENT CONDITIONS The subject parcel is located on the west side of Route 32, at its intersection with Powerhouse Road. The lot currently contains buildings and a driveway. The lot slopes moderately to steeply across its width, generally from the west to the east. Existing soils at this location, as identified in the NRCS Soil Survey of Fairfield County, Connecticut, consist of Narragansett silt loam, 2 to 8 percent slopes, which has a Hydrologic classification of “B”. The existing runoff from a 50-Year rainfall event is 5.10 c.f.s. PROPOSED CONDITIONS: The proposal for this phase is to construct 8 residential units (4 units in Phase 2 and 4 units in Phase 3), with associated driveway, site utilities, and miscellaneous site improvements. The proposed runoff (prior to mitigation) from a 50-Year rainfall event is 6.87 c.f.s. CALCULATIONS: The following computations of the existing and proposed conditions runoff flows were derived from the HydroCAD computer software. HydroCAD follows the NRCS TR-20 procedure for computing stormwater runoff. Computations were performed for a 50-year storm event, which has a 2% chance of occurring in any given 12-month period. Existing Conditions (Phases 2 and 3): Lawn 51,610 s.f. CN 69 Total 51,610 s.f. Weighted CN 69 Stormwater Study –Madision Place 11 February 2025 JNE Holdings, LLC 18 Powerhouse & 145 Route 32 Montville, CT P a g e | 5 FULLER ENGINEERING & LAND SURVEYING, LLC 525 JOHN STREET 2ND FLOOR BRIDGEPORT, CONNECTICUT 06604 PHONE (203)333-9465; FAX (203)336-1769 Proposed Conditions (Phases 2 and 3): Buildings 12,169 s.f. CN 98 Driveway/Parking 10,597 s.f. CN 98 Lawn 28,844 s.f. CN 69 Total - 51,610 s.f. Weighted CN 82 Groundwater Recharge Volume (GWV): Impervious area = 44.1 % WQV = (0.4469 * 1.185 ac)/12 x 1.3 = 0.0573707 ac-ft = 2,499.1 ft3 GWV = 2,499.1 * 0.25 = 624.8 ft3 SUMMARY: 50 Year 25Yr. 10Yr. 5Yr. 2Yr. Existing Runoff 5.10 c.f.s 4.13 2.91 2.08 1.17 Proposed Runoff 6.87 c.f.s. 5.84 4.49 3.52 2.39 Runoff Retained: 2.97 c.f.s. 2.61 2.15 1.81 1.40 Areas Bypassing Retention Plus overflow: 3.86 c.f.s. 3.19 2.33 1.74 1.07 CONCLUSIONS: The increased runoff resulting from the proposed site improvements will be retained in an on- site retention system. The runoff from the driveway and the roof of the northern building will be routed to 384 linear feet of 48” concrete galleries. The increase in stormwater runoff is mitigated on-site. This system will reduce the net peak run-off during a 50 Year (2%) rainfall event to 3.86 c.f.s. from its current peak of 5.10 c.f.s. The bottom of the concrete galleries will be at elevation 99.0. No restrictive layer was found to an elevation of 98.0. The proposed retention system provides a total of 6,128 ft3 of storage, which will be adequate to maintain the net runoff during a 50 Year rainfall event, meets the Water Quality Volume and will provide groundwater recharge. Stormwater Study –Madision Place 11 February 2025 JNE Holdings, LLC 18 Powerhouse & 145 Route 32 Montville, CT P a g e | 6 FULLER ENGINEERING & LAND SURVEYING, LLC 525 JOHN STREET 2ND FLOOR BRIDGEPORT, CONNECTICUT 06604 PHONE (203)333-9465; FAX (203)336-1769 The maximum peak net runoff from the proposed conditions decrease compared to the peak runoff from the existing conditions for each of the rainfall events from the 2 Year to the 50 Year rainfall events, as the table above illustrates. The proposed improvements will have no adverse impact on surrounding properties. SOIL EROSION AND SEDIMENTATION CONTROL (All Phases) For temporary condition or during construction a silt fence shall be provided along the property lines. Anti-tracking aprons shall be provided at all access routes from the site to the public road. A temporary diversion berm with stone check dams @ 50 ft o.c. shall be maintained and relocated as required during construction. All planting areas shall be protected with slope stabilization measures. For permanent condition, all embankments, after being stabilized, shall be seeded to lawn or seed mixture as specified. Newly planted areas shall be covered with straw or erosion control blankets. APPENDIX “A” MONTVILLE PRECIPITATION FREQUENCY (PF) RAINFALL DATA #245 Norwich New London Road (CT State RTE. 32) Montville, CT APPENDIX “B” NRCS SOIL MAP AND HYDROLOGIC SOIL GROUP RATINGS Soil Map—State of Connecticut, Eastern Part Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 2/8/2025 Page 1 of 34590530459055045905704590590459061045906304590650459055045905704590590459061045906304590650741450741470741490741510741530741550741570741590741610741630 741450 741470 741490 741510 741530 741550 741570 741590 741610 741630 41° 25' 52'' N 72° 6' 37'' W41° 25' 52'' N72° 6' 28'' W41° 25' 48'' N 72° 6' 37'' W41° 25' 48'' N 72° 6' 28'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS84 0 40 80 160 240 Feet 0 10 20 40 60 Meters Map Scale: 1:894 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 Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:12,000. 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: State of Connecticut, Eastern Part Survey Area Data: Version 2, Aug 30, 2024 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jun 14, 2022—Oct 6, 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. Soil Map—State of Connecticut, Eastern Part Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 2/8/2025 Page 2 of 3 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 38C Hinckley loamy sand, 3 to 15 percent slopes 0.1 3.2% 66B Narragansett silt loam, 2 to 8 percent slopes 2.4 96.0% 68C Narragansett silt loam, 3 to 15 percent slopes, extremely stony 0.0 0.7% Totals for Area of Interest 2.5 100.0% Soil Map—State of Connecticut, Eastern Part Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 2/8/2025 Page 3 of 3 APPENDIX “C” HYDROCAD ANALYSIS PHASE 1 1S Existing Conditions Routing Diagram for 2578Existing Prepared by Fairfield County Engineering LLC, Printed 2/6/2025 HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 2 Year Rainfall=3.54"2578Existing Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 6HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Conditions Runoff =1.42 cfs @ 12.12 hrs, Volume=0.115 af, Depth>1.03" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 2 Year Rainfall=3.54" Area (sf)CN Description *1,072 98 Buildings *1,107 98 Driveway *243 98 Concrete slab 55,821 69 50-75% Grass cover, Fair, HSG B 58,243 70 Weighted Average 55,821 95.84% Pervious Area 2,422 4.16% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 1S: Existing Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 2 Year Rainfall=3.54" Runoff Area=58,243 sf Runoff Volume=0.115 af Runoff Depth>1.03" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=70 1.42 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 5 Year Rainfall=4.55"2578Existing Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 7HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Conditions Runoff =2.47 cfs @ 12.11 hrs, Volume=0.190 af, Depth>1.71" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 5 Year Rainfall=4.55" Area (sf)CN Description *1,072 98 Buildings *1,107 98 Driveway *243 98 Concrete slab 55,821 69 50-75% Grass cover, Fair, HSG B 58,243 70 Weighted Average 55,821 95.84% Pervious Area 2,422 4.16% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 1S: Existing Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 5 Year Rainfall=4.55" Runoff Area=58,243 sf Runoff Volume=0.190 af Runoff Depth>1.71" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=70 2.47 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 10 Year Rainfall=5.39"2578Existing Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 8HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Conditions Runoff =3.42 cfs @ 12.11 hrs, Volume=0.259 af, Depth>2.33" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 10 Year Rainfall=5.39" Area (sf)CN Description *1,072 98 Buildings *1,107 98 Driveway *243 98 Concrete slab 55,821 69 50-75% Grass cover, Fair, HSG B 58,243 70 Weighted Average 55,821 95.84% Pervious Area 2,422 4.16% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 1S: Existing Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Type III 24-hr 10 Year Rainfall=5.39" Runoff Area=58,243 sf Runoff Volume=0.259 af Runoff Depth>2.33" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=70 3.42 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 25 Year Rainfall=6.55"2578Existing Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 9HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Conditions Runoff =4.81 cfs @ 12.11 hrs, Volume=0.361 af, Depth>3.24" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 25 Year Rainfall=6.55" Area (sf)CN Description *1,072 98 Buildings *1,107 98 Driveway *243 98 Concrete slab 55,821 69 50-75% Grass cover, Fair, HSG B 58,243 70 Weighted Average 55,821 95.84% Pervious Area 2,422 4.16% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 1S: Existing Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)5 4 3 2 1 0 Type III 24-hr 25 Year Rainfall=6.55" Runoff Area=58,243 sf Runoff Volume=0.361 af Runoff Depth>3.24" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=70 4.81 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 50 Year Rainfall=7.44"2578Existing Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 10HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Conditions Runoff =5.92 cfs @ 12.11 hrs, Volume=0.444 af, Depth>3.98" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 50 Year Rainfall=7.44" Area (sf)CN Description *1,072 98 Buildings *1,107 98 Driveway *243 98 Concrete slab 55,821 69 50-75% Grass cover, Fair, HSG B 58,243 70 Weighted Average 55,821 95.84% Pervious Area 2,422 4.16% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 1S: Existing Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)6 5 4 3 2 1 0 Type III 24-hr 50 Year Rainfall=7.44" Runoff Area=58,243 sf Runoff Volume=0.444 af Runoff Depth>3.98" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=70 5.92 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. 2S Proposed Conditions Routing Diagram for 2578Proposed Prepared by Fairfield County Engineering LLC, Printed 2/6/2025 HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 2 Year Rainfall=3.54"2578Proposed Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 12HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Conditions Runoff =2.03 cfs @ 12.11 hrs, Volume=0.155 af, Depth>1.39" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 2 Year Rainfall=3.54" Area (sf)CN Description *4,741 98 Building *9,018 98 Driveway/Parking 44,484 69 50-75% Grass cover, Fair, HSG B 58,243 76 Weighted Average 44,484 76.38% Pervious Area 13,759 23.62% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 2S: Proposed Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 2 Year Rainfall=3.54" Runoff Area=58,243 sf Runoff Volume=0.155 af Runoff Depth>1.39" Flow Length=353' Tc=7.2 min CN=76 2.03 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 5 Year Rainfall=4.55"2578Proposed Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 13HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Conditions Runoff =3.21 cfs @ 12.11 hrs, Volume=0.241 af, Depth>2.17" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 5 Year Rainfall=4.55" Area (sf)CN Description *4,741 98 Building *9,018 98 Driveway/Parking 44,484 69 50-75% Grass cover, Fair, HSG B 58,243 76 Weighted Average 44,484 76.38% Pervious Area 13,759 23.62% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 2S: Proposed Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Type III 24-hr 5 Year Rainfall=4.55" Runoff Area=58,243 sf Runoff Volume=0.241 af Runoff Depth>2.17" Flow Length=353' Tc=7.2 min CN=76 3.21 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 10 Year Rainfall=5.39"2578Proposed Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 14HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Conditions Runoff =4.24 cfs @ 12.11 hrs, Volume=0.318 af, Depth>2.86" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 10 Year Rainfall=5.39" Area (sf)CN Description *4,741 98 Building *9,018 98 Driveway/Parking 44,484 69 50-75% Grass cover, Fair, HSG B 58,243 76 Weighted Average 44,484 76.38% Pervious Area 13,759 23.62% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 2S: Proposed Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)4 3 2 1 0 Type III 24-hr 10 Year Rainfall=5.39" Runoff Area=58,243 sf Runoff Volume=0.318 af Runoff Depth>2.86" Flow Length=353' Tc=7.2 min CN=76 4.24 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 25 Year Rainfall=6.55"2578Proposed Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 15HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Conditions Runoff =5.72 cfs @ 12.11 hrs, Volume=0.430 af, Depth>3.85" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 25 Year Rainfall=6.55" Area (sf)CN Description *4,741 98 Building *9,018 98 Driveway/Parking 44,484 69 50-75% Grass cover, Fair, HSG B 58,243 76 Weighted Average 44,484 76.38% Pervious Area 13,759 23.62% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 2S: Proposed Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)6 5 4 3 2 1 0 Type III 24-hr 25 Year Rainfall=6.55" Runoff Area=58,243 sf Runoff Volume=0.430 af Runoff Depth>3.85" Flow Length=353' Tc=7.2 min CN=76 5.72 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 50 Year Rainfall=7.44"2578Proposed Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 16HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Conditions Runoff =6.88 cfs @ 12.10 hrs, Volume=0.518 af, Depth>4.65" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 50 Year Rainfall=7.44" Area (sf)CN Description *4,741 98 Building *9,018 98 Driveway/Parking 44,484 69 50-75% Grass cover, Fair, HSG B 58,243 76 Weighted Average 44,484 76.38% Pervious Area 13,759 23.62% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 2S: Proposed Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)7 6 5 4 3 2 1 0 Type III 24-hr 50 Year Rainfall=7.44" Runoff Area=58,243 sf Runoff Volume=0.518 af Runoff Depth>4.65" Flow Length=353' Tc=7.2 min CN=76 6.88 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. 3S Areas Routed to Retention 4S Areas not Routed to Retention 1P 48" Concrete Galleries 1L Combined Hydrograph Routing Diagram for 2578Combined Prepared by Fairfield County Engineering LLC, Printed 2/6/2025 HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 2 Year Rainfall=3.54"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 18HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Areas Routed to Retention Runoff =0.73 cfs @ 12.07 hrs, Volume=0.057 af, Depth>3.30" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 2 Year Rainfall=3.54" Area (sf)CN Description *9,018 98 Driveway/Parking 9,018 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Direct Subcatchment 3S: Areas Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)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 2 Year Rainfall=3.54" Runoff Area=9,018 sf Runoff Volume=0.057 af Runoff Depth>3.30" Tc=5.0 min CN=98 0.73 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 2 Year Rainfall=3.54"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 19HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: Areas not Routed to Retention Runoff =1.36 cfs @ 12.12 hrs, Volume=0.108 af, Depth>1.15" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 2 Year Rainfall=3.54" Area (sf)CN Description *4,741 98 Building 44,484 69 50-75% Grass cover, Fair, HSG B 49,225 72 Weighted Average 44,484 90.37% Pervious Area 4,741 9.63% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 4S: Areas not Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 2 Year Rainfall=3.54" Runoff Area=49,225 sf Runoff Volume=0.108 af Runoff Depth>1.15" Flow Length=353' Tc=7.2 min CN=72 1.36 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 2 Year Rainfall=3.54"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 20HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1P: 48" Concrete Galleries Inflow Area =0.207 ac,100.00% Impervious, Inflow Depth > 3.30" for 2 Year event Inflow =0.73 cfs @ 12.07 hrs, Volume=0.057 af Outflow =0.00 cfs @ 0.00 hrs, Volume=0.000 af, Atten= 100%, Lag= 0.0 min Primary =0.00 cfs @ 0.00 hrs, Volume=0.000 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Peak Elev= 100.03' @ 24.00 hrs Surf.Area= 900 sf Storage= 2,483 cf Plug-Flow detention time= (not calculated: initial storage exceeds outflow) Center-of-Mass det. time= (not calculated: no outflow) Volume Invert Avail.Storage Storage Description #1 97.00'313 cf 18.00'W x 50.00'L x 4.00'H Stone 3,600 cf Overall - 2,819 cf Embedded = 781 cf x 40.0% Voids #2 97.00'2,819 cf 16.00'W x 48.00'L x 3.67'H 48" Concrete Galleries Inside #1 3,131 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 101.00'6.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=97.00' (Free Discharge) 1=Orifice/Grate ( Controls 0.00 cfs) Pond 1P: 48" Concrete Galleries Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)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=0.207 ac Peak Elev=100.03' Storage=2,483 cf 0.73 cfs 0.00 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 2 Year Rainfall=3.54"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 21HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Link 1L: Combined Hydrograph Inflow Area =1.337 ac,23.62% Impervious, Inflow Depth > 0.97" for 2 Year event Inflow =1.36 cfs @ 12.12 hrs, Volume=0.108 af Primary =1.36 cfs @ 12.12 hrs, Volume=0.108 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Link 1L: Combined Hydrograph Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=1.337 ac 1.36 cfs 1.36 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 5 Year Rainfall=4.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 22HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Areas Routed to Retention Runoff =0.94 cfs @ 12.07 hrs, Volume=0.074 af, Depth>4.31" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 5 Year Rainfall=4.55" Area (sf)CN Description *9,018 98 Driveway/Parking 9,018 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Direct Subcatchment 3S: Areas Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 5 Year Rainfall=4.55" Runoff Area=9,018 sf Runoff Volume=0.074 af Runoff Depth>4.31" Tc=5.0 min CN=98 0.94 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 5 Year Rainfall=4.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 23HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: Areas not Routed to Retention Runoff =2.29 cfs @ 12.11 hrs, Volume=0.175 af, Depth>1.85" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 5 Year Rainfall=4.55" Area (sf)CN Description *4,741 98 Building 44,484 69 50-75% Grass cover, Fair, HSG B 49,225 72 Weighted Average 44,484 90.37% Pervious Area 4,741 9.63% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 4S: Areas not Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 5 Year Rainfall=4.55" Runoff Area=49,225 sf Runoff Volume=0.175 af Runoff Depth>1.85" Flow Length=353' Tc=7.2 min CN=72 2.29 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 5 Year Rainfall=4.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 24HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1P: 48" Concrete Galleries Inflow Area =0.207 ac,100.00% Impervious, Inflow Depth > 4.31" for 5 Year event Inflow =0.94 cfs @ 12.07 hrs, Volume=0.074 af Outflow =0.02 cfs @ 20.96 hrs, Volume=0.003 af, Atten= 98%, Lag= 533.3 min Primary =0.02 cfs @ 20.96 hrs, Volume=0.003 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Peak Elev= 101.02' @ 20.96 hrs Surf.Area= 900 sf Storage= 3,131 cf Plug-Flow detention time= 1,099.5 min calculated for 0.003 af (3% of inflow) Center-of-Mass det. time= 595.1 min ( 1,343.5 - 748.3 ) Volume Invert Avail.Storage Storage Description #1 97.00'313 cf 18.00'W x 50.00'L x 4.00'H Stone 3,600 cf Overall - 2,819 cf Embedded = 781 cf x 40.0% Voids #2 97.00'2,819 cf 16.00'W x 48.00'L x 3.67'H 48" Concrete Galleries Inside #1 3,131 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 101.00'6.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.02 cfs @ 20.96 hrs HW=101.02' (Free Discharge) 1=Orifice/Grate (Weir Controls 0.02 cfs @ 0.48 fps) Pond 1P: 48" Concrete Galleries Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.207 ac Peak Elev=101.02' Storage=3,131 cf 0.94 cfs 0.02 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 5 Year Rainfall=4.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 25HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Link 1L: Combined Hydrograph Inflow Area =1.337 ac,23.62% Impervious, Inflow Depth > 1.59" for 5 Year event Inflow =2.29 cfs @ 12.11 hrs, Volume=0.177 af Primary =2.29 cfs @ 12.11 hrs, Volume=0.177 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Link 1L: Combined Hydrograph Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Inflow Area=1.337 ac 2.29 cfs 2.29 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 10 Year Rainfall=5.39"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 26HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Areas Routed to Retention Runoff =1.11 cfs @ 12.07 hrs, Volume=0.089 af, Depth>5.15" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 10 Year Rainfall=5.39" Area (sf)CN Description *9,018 98 Driveway/Parking 9,018 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Direct Subcatchment 3S: Areas Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 10 Year Rainfall=5.39" Runoff Area=9,018 sf Runoff Volume=0.089 af Runoff Depth>5.15" Tc=5.0 min CN=98 1.11 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 10 Year Rainfall=5.39"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 27HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: Areas not Routed to Retention Runoff =3.12 cfs @ 12.11 hrs, Volume=0.235 af, Depth>2.50" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 10 Year Rainfall=5.39" Area (sf)CN Description *4,741 98 Building 44,484 69 50-75% Grass cover, Fair, HSG B 49,225 72 Weighted Average 44,484 90.37% Pervious Area 4,741 9.63% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 4S: Areas not Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Type III 24-hr 10 Year Rainfall=5.39" Runoff Area=49,225 sf Runoff Volume=0.235 af Runoff Depth>2.50" Flow Length=353' Tc=7.2 min CN=72 3.12 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 10 Year Rainfall=5.39"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 28HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1P: 48" Concrete Galleries Inflow Area =0.207 ac,100.00% Impervious, Inflow Depth > 5.15" for 10 Year event Inflow =1.11 cfs @ 12.07 hrs, Volume=0.089 af Outflow =0.10 cfs @ 14.24 hrs, Volume=0.017 af, Atten= 91%, Lag= 130.1 min Primary =0.10 cfs @ 14.24 hrs, Volume=0.017 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Peak Elev= 101.07' @ 14.24 hrs Surf.Area= 900 sf Storage= 3,131 cf Plug-Flow detention time= 590.2 min calculated for 0.017 af (19% of inflow) Center-of-Mass det. time= 318.3 min ( 1,063.9 - 745.5 ) Volume Invert Avail.Storage Storage Description #1 97.00'313 cf 18.00'W x 50.00'L x 4.00'H Stone 3,600 cf Overall - 2,819 cf Embedded = 781 cf x 40.0% Voids #2 97.00'2,819 cf 16.00'W x 48.00'L x 3.67'H 48" Concrete Galleries Inside #1 3,131 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 101.00'6.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.09 cfs @ 14.24 hrs HW=101.07' (Free Discharge) 1=Orifice/Grate (Weir Controls 0.09 cfs @ 0.86 fps) Pond 1P: 48" Concrete Galleries Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.207 ac Peak Elev=101.07' Storage=3,131 cf 1.11 cfs 0.10 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 10 Year Rainfall=5.39"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 29HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Link 1L: Combined Hydrograph Inflow Area =1.337 ac,23.62% Impervious, Inflow Depth > 2.26" for 10 Year event Inflow =3.12 cfs @ 12.11 hrs, Volume=0.252 af Primary =3.12 cfs @ 12.11 hrs, Volume=0.252 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Link 1L: Combined Hydrograph Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Inflow Area=1.337 ac 3.12 cfs 3.12 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 25 Year Rainfall=6.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 30HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Areas Routed to Retention Runoff =1.36 cfs @ 12.07 hrs, Volume=0.109 af, Depth>6.31" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 25 Year Rainfall=6.55" Area (sf)CN Description *9,018 98 Driveway/Parking 9,018 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Direct Subcatchment 3S: Areas Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 25 Year Rainfall=6.55" Runoff Area=9,018 sf Runoff Volume=0.109 af Runoff Depth>6.31" Tc=5.0 min CN=98 1.36 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 25 Year Rainfall=6.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 31HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: Areas not Routed to Retention Runoff =4.32 cfs @ 12.11 hrs, Volume=0.324 af, Depth>3.44" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 25 Year Rainfall=6.55" Area (sf)CN Description *4,741 98 Building 44,484 69 50-75% Grass cover, Fair, HSG B 49,225 72 Weighted Average 44,484 90.37% Pervious Area 4,741 9.63% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 4S: Areas not Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)4 3 2 1 0 Type III 24-hr 25 Year Rainfall=6.55" Runoff Area=49,225 sf Runoff Volume=0.324 af Runoff Depth>3.44" Flow Length=353' Tc=7.2 min CN=72 4.32 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 25 Year Rainfall=6.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 32HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1P: 48" Concrete Galleries Inflow Area =0.207 ac,100.00% Impervious, Inflow Depth > 6.31" for 25 Year event Inflow =1.36 cfs @ 12.07 hrs, Volume=0.109 af Outflow =0.34 cfs @ 12.46 hrs, Volume=0.037 af, Atten= 75%, Lag= 23.2 min Primary =0.34 cfs @ 12.46 hrs, Volume=0.037 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Peak Elev= 101.18' @ 12.46 hrs Surf.Area= 900 sf Storage= 3,131 cf Plug-Flow detention time= 381.6 min calculated for 0.037 af (34% of inflow) Center-of-Mass det. time= 199.0 min ( 941.5 - 742.6 ) Volume Invert Avail.Storage Storage Description #1 97.00'313 cf 18.00'W x 50.00'L x 4.00'H Stone 3,600 cf Overall - 2,819 cf Embedded = 781 cf x 40.0% Voids #2 97.00'2,819 cf 16.00'W x 48.00'L x 3.67'H 48" Concrete Galleries Inside #1 3,131 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 101.00'6.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.30 cfs @ 12.46 hrs HW=101.15' (Free Discharge) 1=Orifice/Grate (Weir Controls 0.30 cfs @ 1.27 fps) Pond 1P: 48" Concrete Galleries Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.207 ac Peak Elev=101.18' Storage=3,131 cf 1.36 cfs 0.34 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 25 Year Rainfall=6.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 33HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Link 1L: Combined Hydrograph Inflow Area =1.337 ac,23.62% Impervious, Inflow Depth > 3.24" for 25 Year event Inflow =4.32 cfs @ 12.11 hrs, Volume=0.361 af Primary =4.32 cfs @ 12.11 hrs, Volume=0.361 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Link 1L: Combined Hydrograph Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)4 3 2 1 0 Inflow Area=1.337 ac 4.32 cfs 4.32 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 50 Year Rainfall=7.44"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 34HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Areas Routed to Retention Runoff =1.54 cfs @ 12.07 hrs, Volume=0.124 af, Depth>7.20" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 50 Year Rainfall=7.44" Area (sf)CN Description *9,018 98 Driveway/Parking 9,018 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Direct Subcatchment 3S: Areas Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 50 Year Rainfall=7.44" Runoff Area=9,018 sf Runoff Volume=0.124 af Runoff Depth>7.20" Tc=5.0 min CN=98 1.54 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 50 Year Rainfall=7.44"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 35HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: Areas not Routed to Retention Runoff =5.28 cfs @ 12.11 hrs, Volume=0.396 af, Depth>4.20" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 50 Year Rainfall=7.44" Area (sf)CN Description *4,741 98 Building 44,484 69 50-75% Grass cover, Fair, HSG B 49,225 72 Weighted Average 44,484 90.37% Pervious Area 4,741 9.63% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 4S: Areas not Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)5 4 3 2 1 0 Type III 24-hr 50 Year Rainfall=7.44" Runoff Area=49,225 sf Runoff Volume=0.396 af Runoff Depth>4.20" Flow Length=353' Tc=7.2 min CN=72 5.28 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 50 Year Rainfall=7.44"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 36HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1P: 48" Concrete Galleries Inflow Area =0.207 ac,100.00% Impervious, Inflow Depth > 7.20" for 50 Year event Inflow =1.54 cfs @ 12.07 hrs, Volume=0.124 af Outflow =1.40 cfs @ 12.24 hrs, Volume=0.054 af, Atten= 9%, Lag= 10.0 min Primary =1.40 cfs @ 12.24 hrs, Volume=0.054 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Peak Elev= 103.21' @ 12.24 hrs Surf.Area= 900 sf Storage= 3,131 cf Plug-Flow detention time= 308.5 min calculated for 0.054 af (43% of inflow) Center-of-Mass det. time= 157.6 min ( 898.4 - 740.9 ) Volume Invert Avail.Storage Storage Description #1 97.00'313 cf 18.00'W x 50.00'L x 4.00'H Stone 3,600 cf Overall - 2,819 cf Embedded = 781 cf x 40.0% Voids #2 97.00'2,819 cf 16.00'W x 48.00'L x 3.67'H 48" Concrete Galleries Inside #1 3,131 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 101.00'6.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=1.40 cfs @ 12.24 hrs HW=103.20' (Free Discharge) 1=Orifice/Grate (Orifice Controls 1.40 cfs @ 7.13 fps) Pond 1P: 48" Concrete Galleries Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.207 ac Peak Elev=103.21' Storage=3,131 cf 1.54 cfs 1.40 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 50 Year Rainfall=7.44"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 37HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Link 1L: Combined Hydrograph Inflow Area =1.337 ac,23.62% Impervious, Inflow Depth > 4.03" for 50 Year event Inflow =5.28 cfs @ 12.11 hrs, Volume=0.449 af Primary =5.28 cfs @ 12.11 hrs, Volume=0.449 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Link 1L: Combined Hydrograph Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)5 4 3 2 1 0 Inflow Area=1.337 ac 5.28 cfs 5.28 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. APPENDIX “D” HYDROCAD ANALYSIS PHASE 2 1S Existing Conditions Routing Diagram for 2578Existing Prepared by Fairfield County Engineering LLC, Printed 2/6/2025 HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 2 Year Rainfall=3.54"2578Existing Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 6HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Conditions Runoff =1.17 cfs @ 12.12 hrs, Volume=0.096 af, Depth>0.98" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 2 Year Rainfall=3.54" Area (sf)CN Description 51,610 69 50-75% Grass cover, Fair, HSG B 51,610 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 1S: Existing Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 2 Year Rainfall=3.54" Runoff Area=51,610 sf Runoff Volume=0.096 af Runoff Depth>0.98" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=69 1.17 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 5 Year Rainfall=4.55"2578Existing Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 7HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Conditions Runoff =2.08 cfs @ 12.11 hrs, Volume=0.161 af, Depth>1.63" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 5 Year Rainfall=4.55" Area (sf)CN Description 51,610 69 50-75% Grass cover, Fair, HSG B 51,610 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 1S: Existing Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 5 Year Rainfall=4.55" Runoff Area=51,610 sf Runoff Volume=0.161 af Runoff Depth>1.63" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=69 2.08 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 10 Year Rainfall=5.39"2578Existing Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 8HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Conditions Runoff =2.91 cfs @ 12.11 hrs, Volume=0.221 af, Depth>2.24" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 10 Year Rainfall=5.39" Area (sf)CN Description 51,610 69 50-75% Grass cover, Fair, HSG B 51,610 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 1S: Existing Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Type III 24-hr 10 Year Rainfall=5.39" Runoff Area=51,610 sf Runoff Volume=0.221 af Runoff Depth>2.24" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=69 2.91 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 25 Year Rainfall=6.55"2578Existing Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 9HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Conditions Runoff =4.13 cfs @ 12.11 hrs, Volume=0.310 af, Depth>3.14" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 25 Year Rainfall=6.55" Area (sf)CN Description 51,610 69 50-75% Grass cover, Fair, HSG B 51,610 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 1S: Existing Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)4 3 2 1 0 Type III 24-hr 25 Year Rainfall=6.55" Runoff Area=51,610 sf Runoff Volume=0.310 af Runoff Depth>3.14" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=69 4.13 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 50 Year Rainfall=7.44"2578Existing Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 10HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Conditions Runoff =5.10 cfs @ 12.11 hrs, Volume=0.382 af, Depth>3.87" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 50 Year Rainfall=7.44" Area (sf)CN Description 51,610 69 50-75% Grass cover, Fair, HSG B 51,610 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 1S: Existing Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)5 4 3 2 1 0 Type III 24-hr 50 Year Rainfall=7.44" Runoff Area=51,610 sf Runoff Volume=0.382 af Runoff Depth>3.87" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=69 5.10 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. 2S Proposed Conditions Routing Diagram for 2578Proposed Prepared by Fairfield County Engineering LLC, Printed 2/6/2025 HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 2 Year Rainfall=3.54"2578Proposed Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 12HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Conditions Runoff =2.39 cfs @ 12.11 hrs, Volume=0.179 af, Depth>1.81" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 2 Year Rainfall=3.54" Area (sf)CN Description *12,169 98 Buildings *10,597 98 Driveway/Parking 28,844 69 50-75% Grass cover, Fair, HSG B 51,610 82 Weighted Average 28,844 55.89% Pervious Area 22,766 44.11% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 2S: Proposed Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 2 Year Rainfall=3.54" Runoff Area=51,610 sf Runoff Volume=0.179 af Runoff Depth>1.81" Flow Length=353' Tc=7.2 min CN=82 2.39 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 5 Year Rainfall=4.55"2578Proposed Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 13HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Conditions Runoff =3.52 cfs @ 12.11 hrs, Volume=0.264 af, Depth>2.68" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 5 Year Rainfall=4.55" Area (sf)CN Description *12,169 98 Buildings *10,597 98 Driveway/Parking 28,844 69 50-75% Grass cover, Fair, HSG B 51,610 82 Weighted Average 28,844 55.89% Pervious Area 22,766 44.11% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 2S: Proposed Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Type III 24-hr 5 Year Rainfall=4.55" Runoff Area=51,610 sf Runoff Volume=0.264 af Runoff Depth>2.68" Flow Length=353' Tc=7.2 min CN=82 3.52 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 10 Year Rainfall=5.39"2578Proposed Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 14HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Conditions Runoff =4.49 cfs @ 12.10 hrs, Volume=0.338 af, Depth>3.43" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 10 Year Rainfall=5.39" Area (sf)CN Description *12,169 98 Buildings *10,597 98 Driveway/Parking 28,844 69 50-75% Grass cover, Fair, HSG B 51,610 82 Weighted Average 28,844 55.89% Pervious Area 22,766 44.11% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 2S: Proposed Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)5 4 3 2 1 0 Type III 24-hr 10 Year Rainfall=5.39" Runoff Area=51,610 sf Runoff Volume=0.338 af Runoff Depth>3.43" Flow Length=353' Tc=7.2 min CN=82 4.49 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 25 Year Rainfall=6.55"2578Proposed Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 15HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Conditions Runoff =5.84 cfs @ 12.10 hrs, Volume=0.443 af, Depth>4.49" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 25 Year Rainfall=6.55" Area (sf)CN Description *12,169 98 Buildings *10,597 98 Driveway/Parking 28,844 69 50-75% Grass cover, Fair, HSG B 51,610 82 Weighted Average 28,844 55.89% Pervious Area 22,766 44.11% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 2S: Proposed Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)6 5 4 3 2 1 0 Type III 24-hr 25 Year Rainfall=6.55" Runoff Area=51,610 sf Runoff Volume=0.443 af Runoff Depth>4.49" Flow Length=353' Tc=7.2 min CN=82 5.84 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 50 Year Rainfall=7.44"2578Proposed Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 16HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Conditions Runoff =6.87 cfs @ 12.10 hrs, Volume=0.526 af, Depth>5.32" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 50 Year Rainfall=7.44" Area (sf)CN Description *12,169 98 Buildings *10,597 98 Driveway/Parking 28,844 69 50-75% Grass cover, Fair, HSG B 51,610 82 Weighted Average 28,844 55.89% Pervious Area 22,766 44.11% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 2S: Proposed Conditions Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)7 6 5 4 3 2 1 0 Type III 24-hr 50 Year Rainfall=7.44" Runoff Area=51,610 sf Runoff Volume=0.526 af Runoff Depth>5.32" Flow Length=353' Tc=7.2 min CN=82 6.87 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. 3S Areas Routed to Retention 4S Areas not Routed to Retention 1P 48" Concrete Galleries 1L Combined Hydrograph Routing Diagram for 2578Combined Prepared by Fairfield County Engineering LLC, Printed 2/6/2025 HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 2 Year Rainfall=3.54"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 18HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Areas Routed to Retention Runoff =1.40 cfs @ 12.07 hrs, Volume=0.110 af, Depth>3.30" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 2 Year Rainfall=3.54" Area (sf)CN Description *10,597 98 Driveway/Parking *6,755 98 Portion of Building roof 17,352 98 Weighted Average 17,352 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Direct Subcatchment 3S: Areas Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 2 Year Rainfall=3.54" Runoff Area=17,352 sf Runoff Volume=0.110 af Runoff Depth>3.30" Tc=5.0 min CN=98 1.40 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 2 Year Rainfall=3.54"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 19HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: Areas not Routed to Retention Runoff =1.07 cfs @ 12.11 hrs, Volume=0.083 af, Depth>1.27" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 2 Year Rainfall=3.54" Area (sf)CN Description *5,414 98 Buildings 28,844 69 50-75% Grass cover, Fair, HSG B 34,258 74 Weighted Average 28,844 84.20% Pervious Area 5,414 15.80% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 4S: Areas not Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 2 Year Rainfall=3.54" Runoff Area=34,258 sf Runoff Volume=0.083 af Runoff Depth>1.27" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=74 1.07 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 2 Year Rainfall=3.54"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 20HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1P: 48" Concrete Galleries Inflow Area =0.398 ac,100.00% Impervious, Inflow Depth > 3.30" for 2 Year event Inflow =1.40 cfs @ 12.07 hrs, Volume=0.110 af Outflow =0.00 cfs @ 0.00 hrs, Volume=0.000 af, Atten= 100%, Lag= 0.0 min Primary =0.00 cfs @ 0.00 hrs, Volume=0.000 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Peak Elev= 101.97' @ 24.00 hrs Surf.Area= 1,716 sf Storage= 4,778 cf Plug-Flow detention time= (not calculated: initial storage exceeds outflow) Center-of-Mass det. time= (not calculated: no outflow) Volume Invert Avail.Storage Storage Description #1 99.00'491 cf 26.00'W x 66.00'L x 4.00'H Stone 6,864 cf Overall - 5,637 cf Embedded = 1,227 cf x 40.0% Voids #2 99.00'5,637 cf 24.00'W x 64.00'L x 3.67'H 48" Concrete Galleries Inside #1 6,128 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 103.00'6.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=99.00' (Free Discharge) 1=Orifice/Grate ( Controls 0.00 cfs) Pond 1P: 48" Concrete Galleries Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.398 ac Peak Elev=101.97' Storage=4,778 cf 1.40 cfs 0.00 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 2 Year Rainfall=3.54"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 21HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Link 1L: Combined Hydrograph Inflow Area =1.185 ac,44.11% Impervious, Inflow Depth > 0.84" for 2 Year event Inflow =1.07 cfs @ 12.11 hrs, Volume=0.083 af Primary =1.07 cfs @ 12.11 hrs, Volume=0.083 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Link 1L: Combined Hydrograph Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=1.185 ac 1.07 cfs 1.07 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 5 Year Rainfall=4.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 22HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Areas Routed to Retention Runoff =1.81 cfs @ 12.07 hrs, Volume=0.143 af, Depth>4.31" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 5 Year Rainfall=4.55" Area (sf)CN Description *10,597 98 Driveway/Parking *6,755 98 Portion of Building roof 17,352 98 Weighted Average 17,352 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Direct Subcatchment 3S: Areas Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 5 Year Rainfall=4.55" Runoff Area=17,352 sf Runoff Volume=0.143 af Runoff Depth>4.31" Tc=5.0 min CN=98 1.81 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 5 Year Rainfall=4.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 23HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: Areas not Routed to Retention Runoff =1.74 cfs @ 12.11 hrs, Volume=0.132 af, Depth>2.01" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 5 Year Rainfall=4.55" Area (sf)CN Description *5,414 98 Buildings 28,844 69 50-75% Grass cover, Fair, HSG B 34,258 74 Weighted Average 28,844 84.20% Pervious Area 5,414 15.80% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 4S: Areas not Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 5 Year Rainfall=4.55" Runoff Area=34,258 sf Runoff Volume=0.132 af Runoff Depth>2.01" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=74 1.74 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 5 Year Rainfall=4.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 24HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1P: 48" Concrete Galleries Inflow Area =0.398 ac,100.00% Impervious, Inflow Depth > 4.31" for 5 Year event Inflow =1.81 cfs @ 12.07 hrs, Volume=0.143 af Outflow =0.03 cfs @ 22.36 hrs, Volume=0.002 af, Atten= 98%, Lag= 617.3 min Primary =0.03 cfs @ 22.36 hrs, Volume=0.002 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Peak Elev= 103.03' @ 22.36 hrs Surf.Area= 1,716 sf Storage= 6,128 cf Plug-Flow detention time= 1,201.1 min calculated for 0.002 af (2% of inflow) Center-of-Mass det. time= 639.5 min ( 1,387.8 - 748.3 ) Volume Invert Avail.Storage Storage Description #1 99.00'491 cf 26.00'W x 66.00'L x 4.00'H Stone 6,864 cf Overall - 5,637 cf Embedded = 1,227 cf x 40.0% Voids #2 99.00'5,637 cf 24.00'W x 64.00'L x 3.67'H 48" Concrete Galleries Inside #1 6,128 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 103.00'6.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.03 cfs @ 22.36 hrs HW=103.03' (Free Discharge) 1=Orifice/Grate (Weir Controls 0.03 cfs @ 0.56 fps) Pond 1P: 48" Concrete Galleries Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Inflow Area=0.398 ac Peak Elev=103.03' Storage=6,128 cf 1.81 cfs 0.03 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 5 Year Rainfall=4.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 25HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Link 1L: Combined Hydrograph Inflow Area =1.185 ac,44.11% Impervious, Inflow Depth > 1.36" for 5 Year event Inflow =1.74 cfs @ 12.11 hrs, Volume=0.134 af Primary =1.74 cfs @ 12.11 hrs, Volume=0.134 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Link 1L: Combined Hydrograph Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=1.185 ac 1.74 cfs 1.74 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 10 Year Rainfall=5.39"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 26HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Areas Routed to Retention Runoff =2.15 cfs @ 12.07 hrs, Volume=0.171 af, Depth>5.15" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 10 Year Rainfall=5.39" Area (sf)CN Description *10,597 98 Driveway/Parking *6,755 98 Portion of Building roof 17,352 98 Weighted Average 17,352 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Direct Subcatchment 3S: Areas Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 10 Year Rainfall=5.39" Runoff Area=17,352 sf Runoff Volume=0.171 af Runoff Depth>5.15" Tc=5.0 min CN=98 2.15 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 10 Year Rainfall=5.39"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 27HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: Areas not Routed to Retention Runoff =2.33 cfs @ 12.11 hrs, Volume=0.175 af, Depth>2.68" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 10 Year Rainfall=5.39" Area (sf)CN Description *5,414 98 Buildings 28,844 69 50-75% Grass cover, Fair, HSG B 34,258 74 Weighted Average 28,844 84.20% Pervious Area 5,414 15.80% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 4S: Areas not Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 10 Year Rainfall=5.39" Runoff Area=34,258 sf Runoff Volume=0.175 af Runoff Depth>2.68" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=74 2.33 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 10 Year Rainfall=5.39"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 28HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1P: 48" Concrete Galleries Inflow Area =0.398 ac,100.00% Impervious, Inflow Depth > 5.15" for 10 Year event Inflow =2.15 cfs @ 12.07 hrs, Volume=0.171 af Outflow =0.17 cfs @ 14.52 hrs, Volume=0.030 af, Atten= 92%, Lag= 146.9 min Primary =0.17 cfs @ 14.52 hrs, Volume=0.030 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Peak Elev= 103.10' @ 14.52 hrs Surf.Area= 1,716 sf Storage= 6,128 cf Plug-Flow detention time= 618.1 min calculated for 0.030 af (18% of inflow) Center-of-Mass det. time= 333.6 min ( 1,079.1 - 745.5 ) Volume Invert Avail.Storage Storage Description #1 99.00'491 cf 26.00'W x 66.00'L x 4.00'H Stone 6,864 cf Overall - 5,637 cf Embedded = 1,227 cf x 40.0% Voids #2 99.00'5,637 cf 24.00'W x 64.00'L x 3.67'H 48" Concrete Galleries Inside #1 6,128 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 103.00'6.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.17 cfs @ 14.52 hrs HW=103.10' (Free Discharge) 1=Orifice/Grate (Weir Controls 0.17 cfs @ 1.04 fps) Pond 1P: 48" Concrete Galleries Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Inflow Area=0.398 ac Peak Elev=103.10' Storage=6,128 cf 2.15 cfs 0.17 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 10 Year Rainfall=5.39"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 29HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Link 1L: Combined Hydrograph Inflow Area =1.185 ac,44.11% Impervious, Inflow Depth > 2.08" for 10 Year event Inflow =2.33 cfs @ 12.11 hrs, Volume=0.206 af Primary =2.33 cfs @ 12.11 hrs, Volume=0.206 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Link 1L: Combined Hydrograph Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Inflow Area=1.185 ac 2.33 cfs 2.33 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 25 Year Rainfall=6.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 30HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Areas Routed to Retention Runoff =2.61 cfs @ 12.07 hrs, Volume=0.209 af, Depth>6.31" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 25 Year Rainfall=6.55" Area (sf)CN Description *10,597 98 Driveway/Parking *6,755 98 Portion of Building roof 17,352 98 Weighted Average 17,352 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Direct Subcatchment 3S: Areas Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 25 Year Rainfall=6.55" Runoff Area=17,352 sf Runoff Volume=0.209 af Runoff Depth>6.31" Tc=5.0 min CN=98 2.61 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 25 Year Rainfall=6.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 31HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: Areas not Routed to Retention Runoff =3.19 cfs @ 12.11 hrs, Volume=0.239 af, Depth>3.65" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 25 Year Rainfall=6.55" Area (sf)CN Description *5,414 98 Buildings 28,844 69 50-75% Grass cover, Fair, HSG B 34,258 74 Weighted Average 28,844 84.20% Pervious Area 5,414 15.80% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 4S: Areas not Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Type III 24-hr 25 Year Rainfall=6.55" Runoff Area=34,258 sf Runoff Volume=0.239 af Runoff Depth>3.65" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=74 3.19 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 25 Year Rainfall=6.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 32HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1P: 48" Concrete Galleries Inflow Area =0.398 ac,100.00% Impervious, Inflow Depth > 6.31" for 25 Year event Inflow =2.61 cfs @ 12.07 hrs, Volume=0.209 af Outflow =0.66 cfs @ 12.52 hrs, Volume=0.069 af, Atten= 75%, Lag= 26.6 min Primary =0.66 cfs @ 12.52 hrs, Volume=0.069 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Peak Elev= 103.49' @ 12.52 hrs Surf.Area= 1,716 sf Storage= 6,128 cf Plug-Flow detention time= 392.2 min calculated for 0.069 af (33% of inflow) Center-of-Mass det. time= 204.8 min ( 947.4 - 742.6 ) Volume Invert Avail.Storage Storage Description #1 99.00'491 cf 26.00'W x 66.00'L x 4.00'H Stone 6,864 cf Overall - 5,637 cf Embedded = 1,227 cf x 40.0% Voids #2 99.00'5,637 cf 24.00'W x 64.00'L x 3.67'H 48" Concrete Galleries Inside #1 6,128 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 103.00'6.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.64 cfs @ 12.52 hrs HW=103.45' (Free Discharge) 1=Orifice/Grate (Orifice Controls 0.64 cfs @ 3.24 fps) Pond 1P: 48" Concrete Galleries Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)2 1 0 Inflow Area=0.398 ac Peak Elev=103.49' Storage=6,128 cf 2.61 cfs 0.66 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 25 Year Rainfall=6.55"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 33HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Link 1L: Combined Hydrograph Inflow Area =1.185 ac,44.11% Impervious, Inflow Depth > 3.12" for 25 Year event Inflow =3.19 cfs @ 12.11 hrs, Volume=0.308 af Primary =3.19 cfs @ 12.11 hrs, Volume=0.308 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Link 1L: Combined Hydrograph Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Inflow Area=1.185 ac 3.19 cfs 3.19 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 50 Year Rainfall=7.44"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 34HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Areas Routed to Retention Runoff =2.97 cfs @ 12.07 hrs, Volume=0.239 af, Depth>7.20" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 50 Year Rainfall=7.44" Area (sf)CN Description *10,597 98 Driveway/Parking *6,755 98 Portion of Building roof 17,352 98 Weighted Average 17,352 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.0 Direct Entry, Direct Subcatchment 3S: Areas Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Type III 24-hr 50 Year Rainfall=7.44" Runoff Area=17,352 sf Runoff Volume=0.239 af Runoff Depth>7.20" Tc=5.0 min CN=98 2.97 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 50 Year Rainfall=7.44"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 35HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: Areas not Routed to Retention Runoff =3.86 cfs @ 12.11 hrs, Volume=0.290 af, Depth>4.42" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Type III 24-hr 50 Year Rainfall=7.44" Area (sf)CN Description *5,414 98 Buildings 28,844 69 50-75% Grass cover, Fair, HSG B 34,258 74 Weighted Average 28,844 84.20% Pervious Area 5,414 15.80% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 5.2 100 0.0870 0.32 Sheet Flow, Sheet Flow Grass: Short n= 0.150 P2= 3.54" 2.0 253 0.0870 2.06 Shallow Concentrated Flow, Shallow Concentrated Flow Short Grass Pasture Kv= 7.0 fps 7.2 353 Total Subcatchment 4S: Areas not Routed to Retention Runoff Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)4 3 2 1 0 Type III 24-hr 50 Year Rainfall=7.44" Runoff Area=34,258 sf Runoff Volume=0.290 af Runoff Depth>4.42" Flow Length=353' Slope=0.0870 '/' Tc=7.2 min CN=74 3.86 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type III 24-hr 50 Year Rainfall=7.44"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 36HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1P: 48" Concrete Galleries Inflow Area =0.398 ac,100.00% Impervious, Inflow Depth > 7.20" for 50 Year event Inflow =2.97 cfs @ 12.07 hrs, Volume=0.239 af Outflow =1.46 cfs @ 12.25 hrs, Volume=0.098 af, Atten= 51%, Lag= 10.8 min Primary =1.46 cfs @ 12.25 hrs, Volume=0.098 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Peak Elev= 105.21' @ 12.25 hrs Surf.Area= 1,716 sf Storage= 6,128 cf Plug-Flow detention time= 321.1 min calculated for 0.098 af (41% of inflow) Center-of-Mass det. time= 164.7 min ( 905.6 - 740.9 ) Volume Invert Avail.Storage Storage Description #1 99.00'491 cf 26.00'W x 66.00'L x 4.00'H Stone 6,864 cf Overall - 5,637 cf Embedded = 1,227 cf x 40.0% Voids #2 99.00'5,637 cf 24.00'W x 64.00'L x 3.67'H 48" Concrete Galleries Inside #1 6,128 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 103.00'6.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=1.29 cfs @ 12.25 hrs HW=104.86' (Free Discharge) 1=Orifice/Grate (Orifice Controls 1.29 cfs @ 6.57 fps) Pond 1P: 48" Concrete Galleries Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Inflow Area=0.398 ac Peak Elev=105.21' Storage=6,128 cf 2.97 cfs 1.46 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type III 24-hr 50 Year Rainfall=7.44"2578Combined Printed 2/6/2025Prepared by Fairfield County Engineering LLC Page 37HydroCAD® 10.00-26 s/n 06020 © 2020 HydroCAD Software Solutions LLC Summary for Link 1L: Combined Hydrograph Inflow Area =1.185 ac,44.11% Impervious, Inflow Depth > 3.93" for 50 Year event Inflow =3.86 cfs @ 12.11 hrs, Volume=0.388 af Primary =3.86 cfs @ 12.11 hrs, Volume=0.388 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.04 hrs Link 1L: Combined Hydrograph Inflow Primary Hydrograph Time (hours) 2423222120191817161514131211109876543210Flow (cfs)4 3 2 1 0 Inflow Area=1.185 ac 3.86 cfs 3.86 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. APPENDIX “E” OPERATIONS AND MAINTENANCE PLAN Appendix O Operations and Maintenance Plan 145 Norwich New London Tpke. Route 32 & 18 Powerhouse Road Montville, CT February 11, 2025 Scope: The purpose of the Operations and Maintenance Plan is to ensure that the existing and proposed stormwater components installed at 145 Route 32, Norwich New London Turnpike and 18 Powerhouse Road, Montville, CT are maintained in operational condition throughout the life of the project. The service procedures associated with this plan shall be performed as required by the parties legally responsible for their maintenance. Recommended Frequency of Service: As further defined below, all stormwater components should be checked on a periodic basis and kept in full working order. Ultimately, the required frequency of inspection and service will depend on runoff quantities, pollutant loading, and clogging due to debris. At a minimum, we recommend that all stormwater components be inspected and serviced twice per year, once before winter begins and once during spring cleanup. Qualified Inspector: The inspections must be completed by an individual experienced in the construction and maintenance of stormwater drainage systems. Once every five years the inspections must be completed by a professional engineer. Service Procedures: 1. Catch Basins & Drainage Inlets: a. Catch basins and drainage inlets shall be completely cleaned of accumulated debris and sediments at the completion of construction. b. For the first year, catch basins and drainage inlets shall be inspected on a quarterly basis. c. Any accumulated debris within the catch basins/inlets shall be removed and any repairs as required. d. From the second year onward, visual inspections shall occur twice per year, once in the spring and once in the fall, after fall cleanup of leaves has occurred. e. Accumulated debris within the catch basins/inlets shall be removed and repairs made as required. f. Accumulated sediments shall be removed at which time they are within 12 inches of the invert of the outlet pipe. g. Any additional maintenance required per the manufacturer’s specifications shall also be completed. 2. Storm Drainage Piping and Manholes/Junction Boxes: a. All storm drainage piping shall be completely flushed of debris and accumulated sediment at the completion of construction. b. Manholes/Junction Boxes shall be inspected and repaired on an annual basis. c. Unless system performance indicates degradation of piping, comprehensive video inspection of storm drainage piping shall occur once every ten years. d. Any additional maintenance required per the manufacturer’s specifications shall also be completed. 3. Stormwater Inlet/Control Structures: a. All control structures (orifice, weir, etc.) shall be completely cleaned of accumulated debris and sediments at the completion of construction. Any repairs shall be performed. b. For the first year, control structures (orifice, weir, etc.) shall be inspected on a quarterly basis. c. Any accumulated debris shall be removed and any repairs made to the control structures (orifice, weir, etc.) as required. d. From the second year onward, visual inspections shall occur twice per year, once in the spring and once in the fall, after fall cleanup of leaves has occurred. e. Accumulated debris shall be removed and repairs made as required. f. Any additional maintenance required per the manufacturer’s specifications shall also be completed. 4. Drywells and Infiltration Systems: a. All drywells/infiltrators shall be completely cleaned of accumulated debris and sediments upon the completion of construction. b. For the first year, the drywells/infiltrators shall be inspected on a quarterly basis. c. Any accumulated debris within the drywells/infiltrators shall be removed and any repairs made to the units as required. d. From the second year onward, visual inspection shall occur twice per year, once in the spring and once in the fall, after fall cleanup of leaves has occurred. e. Accumulated debris within the units shall be removed and repairs made as required. f. Any additional maintenance required per the manufacturer’s specifications shall also be completed. 5. Roof Gutters: a. Remove accumulated debris and inspect for damage. Any damage should be repaired as required. Disposal of Debris and Sediment: All debris and sediment removed from the stormwater structures and bioretention/biofiltration basins shall be disposed of legally. There shall be no dumping of silt or debris into or in proximity to any inland or tidal wetlands. Maintenance Records: The Owners(s) must maintain all records (logs, invoices, reports, data, etc.) and have them readily available for inspection at all times. Operations and Maintenance Log (Page 1 of 3) #245 Route 32 Norwich New London Tpke. Montville, CT March 8, 2022 30, _________________________________________________________________________________ Type of Inspection:  Spring  Fall  Other Inspector’s Name:______________________________ Date of Inspection:___________________ Affiliation:_____________________________________ Phone #:___________________________ Catch Basins & Drainage Inlets: · Has accumulated debris been removed from grates?  Yes  No  N/A · Do any basins require additional repair? (identify below):  Yes  No  N/A · Have sumps been cleaned of sediment?  Yes  No  N/A Notes: Storm Drainage Piping and Manholes/Junction Boxes: · Has accumulated debris been removed?  Yes  No  N/A · Do any manholes require additional repair? (identify below):  Yes  No  N/A · Is there any evidence of stormwater piping failure?  Yes  No  N/A · Has a comprehensive video inspection been completed?  Yes  No  N/A Notes: Stormwater Control Structures: · Has accumulated debris been removed?  Yes  No  N/A · Are any repairs required? (identify below):  Yes  No  N/A · Have orifices and weirs been cleaned of debris?  Yes  No  N/A Notes: Operations and Maintenance Log (Page 2 of 3) #245 Route 32 Norwich New London Tpke., Montville, CT March 8, 2022 Drainage Outfalls/Splash Pads/Scour Holes/Level Spreaders: · Have all drainage outlets been cleared of debris?  Yes  No  N/A · Have all outlet protections been inspected/repaired?  Yes  No  N/A · Have all erosion issues been repaired?  Yes  No  N/A Notes: Drywells and Infiltration Systems: · Have units been cleared of debris/sediments?  Yes  No  N/A · Do units require additional repair? (identify below):  Yes  No  N/A · Has draining times of system been verified?  Yes  No  N/A Notes: Roof Gutters: · Has accumulated debris been removed from gutters?  Yes  No  N/A · Do any gutters require additional repair? (identify below):  Yes  No  N/A Notes: Operations and Maintenance Log (Page 3 of 3) #245 Route 32 Norwich New London Tpke. Montville CT March 8, 2022 Please make additional notes/observations and particular concerns below. Also record any additional maintenance that has been performed: __________________________________________________________ _____________________ Signature of Inspector: Date: