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HomeMy WebLinkAboutDrainage Report 12192023May Engineering, LLC Civil Engineering, Site Planning, and Consulting 1297 RT 163 Oakdale, CT 06370 Cell: 860 884-9671 Email: mayengineering@sbcglobal.net DRAINAGE REPORT December 19, 2023 Property Located at: 26 Platoz Drive Uncasville, CT Applicant: JOHN MANDES 11 DEVONSHIRE DR WATERFORD, CT 06385 Owner: MANDES ARTEMIS G 11 DEVONSHIRE DR WATERFORD, CT 06385 Prepared By: Timothy A. May, P.E. May Engineering, LLC 1297 Route 163 Oakdale, CT 03670 Drainage Report for 26 Platoz Dr., Uncasville, CT May Engineering, LLC Civil Engineering, Site Planning, and Consulting 1297 RT 163 Oakdale, CT 06370 Cell: 860 884-9671 Email: mayengineering@sbcglobal.net The proposed development is located at 26 Platoz Dr., Uncasville, CT. The 0.53-acre parcel has a previously approved site plan for a multifamily 4-unit apartment. The site was prepared and a concrete foundation constructed but development was not completed. The concrete foundation was removed due to the concrete being not suitable for construction. The site remained undeveloped and requires a new site plan for the proposed development of the parcel. The parcel is located in the R-20M zone. The applicant/owner John Mandes is proposing a plan of development for multifamily residential use; specifically proposed is a single 64’ x 40’ 4-unit apartment building, paved parking for 10 vehicles, stormwater infiltration for water quality volumes (WQV), and associated underground utilities. SITE DESCRIPTION: The site is a 0.53-acre parcel located on the northeast side of Platoz Drive, located in the Town of Montville, CT. There are no wetlands or water courses located on this parcel. The soil type is primarily a hydraulic soil group B consisting of Charlton-Chatfield complex fine sandy loams. The soil types were evaluated for their permeability and have a moderate infiltration rate. The existing stormwater drainage flow path is across the parcel in a southwesterly direction toward Platoz Drive. No evidence of channelized flows is observed. A majority of stormwater is typically retained onsite due to the topography and previous construction activities. METHODOLOGY AND RESULTS: The stormwater runoff calculation was determined by the Soil Conservation Service SCS TR-20 method (HydroCAD® 10.00-22) using a weighted - CN coefficient to determine stormwater peak runoff and volumetric flows for existing and proposed development for storm events. The HydroCad Stormwater modeling was used to determine stormwater peak runoff flows for existing and proposed development for various storm events. The results correspond to an estimate of the amount of expected disturbed areas to be ~1/4 acre. The summary for existing and proposed development conditions is listed in the appendix of this report. The proposed developed area contains 33% grassed lawn and 29% impervious area including roofs and pavement, with 38% remaining undisturbed wooded forest. The stormwater galleys are designed to store and infiltrate stormwater from roof and paved areas. This is a beneficial part of the Water Quality Volume (WQV) reduction and stormwater management. Also, the amount of stormwater water quality flow (WQF) reduction by the stormwater infiltration trench will adequately provide stormwater storage up to and including the Q10 storm event. Please note the proposed stormwater infiltration trench with concrete 4x4 galleys is sized to remove a significant amount of stormwater runoff from the impervious portion (paved and roof areas). Drainage Report for 26 Platoz Dr., Uncasville, CT May Engineering, LLC Civil Engineering, Site Planning, and Consulting 1297 RT 163 Oakdale, CT 06370 Cell: 860 884-9671 Email: mayengineering@sbcglobal.net Listed are the tabulated results for the existing and proposed development conditions. SUMMARY The proposed site development plan is for construction of a single 4-unit apartment building, paved parking and associated underground utilities. Stormwater runoff will be managed using BMPs that will contain and store the 1” WQV, using the stormwater infiltration trench with 4x4 concrete galleys. The WQF will be reduced as well. The stormwater infiltration trench provides pollutant and stormwater volume reduction. The stormwater infiltration trenches also provide groundwater recharge. Drainage Report for 26 Platoz Dr., Uncasville, CT Soil Map—State of Connecticut, Eastern Part (26 Platoz Dr Uncasville) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/26/2023 Page 1 of 3459376045938104593860459391045939604594010459406045941104594160459376045938104593860459391045939604594010459406045941104594160741900741950742000742050742100742150742200 741900 741950 742000 742050 742100 742150 742200 41° 27' 45'' N 72° 6' 13'' W41° 27' 45'' N72° 5' 58'' W41° 27' 31'' N 72° 6' 13'' W41° 27' 31'' N 72° 5' 58'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS84 0 100 200 400 600 Feet 0 30 60 120 180 Meters Map Scale: 1:2,190 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:12,000. 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 1, Sep 15, 2023 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 (26 Platoz Dr Uncasville) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/26/2023 Page 2 of 3 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 61C Canton and Charlton fine sandy loams, 8 to 15 percent slopes, very stony 0.3 2.1% 62D Canton and Charlton fine sandy loams, 15 to 35 percent slopes, extremely stony 0.7 4.3% 73C Charlton-Chatfield complex, 0 to 15 percent slopes, very rocky 4.4 27.0% 73E Charlton-Chatfield complex, 15 to 45 percent slopes, very rocky 3.9 24.0% 84B Paxton and Montauk fine sandy loams, 3 to 8 percent slopes 6.9 42.6% Totals for Area of Interest 16.2 100.0% Soil Map—State of Connecticut, Eastern Part 26 Platoz Dr Uncasville Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 12/26/2023 Page 3 of 3 1S Existing 1P OutFall Existing Routing Diagram for Existing 26 Platoz Dr Prepared by May Engineering, LLC Timothy May, PE, Printed 12/26/2023 HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Subcat Reach Pond Link Existing - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Existing 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 2HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 0.413 79 <50% Grass cover, Poor, HSG B (1S) 0.236 60 Woods, Fair, HSG B (1S) 0.650 72 TOTAL AREA Existing - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 2-year Rainfall=3.40"Existing 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 3HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Runoff =0.72 cfs @ 12.11 hrs, Volume=0.052 af, Depth>0.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-year Rainfall=3.40" Area (sf)CN Description 10,300 60 Woods, Fair, HSG B 18,000 79 <50% Grass cover, Poor, HSG B 28,300 72 Weighted Average 28,300 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 4.6 30 0.0800 0.11 Sheet Flow, Sheet Flow Woods: Light underbrush n= 0.400 P2= 3.35" 0.4 120 0.8000 4.47 Shallow Concentrated Flow, #1 Shallow conc Woodland Kv= 5.0 fps 2.1 175 0.0200 1.41 Shallow Concentrated Flow, Shallow Concen #2 Nearly Bare & Untilled Kv= 10.0 fps 7.1 325 Total Subcatchment 1S: Existing Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (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=3.40" Runoff Area=28,300 sf Runoff Volume=0.052 af Runoff Depth>0.96" Flow Length=325' Tc=7.1 min CN=72 0.72 cfs Existing - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 5 year Rainfall=4.30"Existing 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 4HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Runoff =1.18 cfs @ 12.11 hrs, Volume=0.083 af, Depth>1.54" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 5 year Rainfall=4.30" Area (sf)CN Description 10,300 60 Woods, Fair, HSG B 18,000 79 <50% Grass cover, Poor, HSG B 28,300 72 Weighted Average 28,300 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 4.6 30 0.0800 0.11 Sheet Flow, Sheet Flow Woods: Light underbrush n= 0.400 P2= 3.35" 0.4 120 0.8000 4.47 Shallow Concentrated Flow, #1 Shallow conc Woodland Kv= 5.0 fps 2.1 175 0.0200 1.41 Shallow Concentrated Flow, Shallow Concen #2 Nearly Bare & Untilled Kv= 10.0 fps 7.1 325 Total Subcatchment 1S: Existing Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)1 0 Type III 24-hr 5 year Rainfall=4.30" Runoff Area=28,300 sf Runoff Volume=0.083 af Runoff Depth>1.54" Flow Length=325' Tc=7.1 min CN=72 1.18 cfs Existing - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 10 year Rainfall=4.80"Existing 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 5HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Runoff =1.46 cfs @ 12.11 hrs, Volume=0.102 af, Depth>1.89" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10 year Rainfall=4.80" Area (sf)CN Description 10,300 60 Woods, Fair, HSG B 18,000 79 <50% Grass cover, Poor, HSG B 28,300 72 Weighted Average 28,300 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 4.6 30 0.0800 0.11 Sheet Flow, Sheet Flow Woods: Light underbrush n= 0.400 P2= 3.35" 0.4 120 0.8000 4.47 Shallow Concentrated Flow, #1 Shallow conc Woodland Kv= 5.0 fps 2.1 175 0.0200 1.41 Shallow Concentrated Flow, Shallow Concen #2 Nearly Bare & Untilled Kv= 10.0 fps 7.1 325 Total Subcatchment 1S: Existing Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)1 0 Type III 24-hr 10 year Rainfall=4.80" Runoff Area=28,300 sf Runoff Volume=0.102 af Runoff Depth>1.89" Flow Length=325' Tc=7.1 min CN=72 1.46 cfs Existing - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 25 year Rainfall=5.70"Existing 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 6HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Runoff =1.98 cfs @ 12.11 hrs, Volume=0.138 af, Depth>2.55" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 25 year Rainfall=5.70" Area (sf)CN Description 10,300 60 Woods, Fair, HSG B 18,000 79 <50% Grass cover, Poor, HSG B 28,300 72 Weighted Average 28,300 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 4.6 30 0.0800 0.11 Sheet Flow, Sheet Flow Woods: Light underbrush n= 0.400 P2= 3.35" 0.4 120 0.8000 4.47 Shallow Concentrated Flow, #1 Shallow conc Woodland Kv= 5.0 fps 2.1 175 0.0200 1.41 Shallow Concentrated Flow, Shallow Concen #2 Nearly Bare & Untilled Kv= 10.0 fps 7.1 325 Total Subcatchment 1S: Existing Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)2 1 0 Type III 24-hr 25 year Rainfall=5.70" Runoff Area=28,300 sf Runoff Volume=0.138 af Runoff Depth>2.55" Flow Length=325' Tc=7.1 min CN=72 1.98 cfs Existing - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 50 year Rainfall=6.30"Existing 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 7HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Runoff =2.34 cfs @ 12.11 hrs, Volume=0.163 af, Depth>3.01" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 50 year Rainfall=6.30" Area (sf)CN Description 10,300 60 Woods, Fair, HSG B 18,000 79 <50% Grass cover, Poor, HSG B 28,300 72 Weighted Average 28,300 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 4.6 30 0.0800 0.11 Sheet Flow, Sheet Flow Woods: Light underbrush n= 0.400 P2= 3.35" 0.4 120 0.8000 4.47 Shallow Concentrated Flow, #1 Shallow conc Woodland Kv= 5.0 fps 2.1 175 0.0200 1.41 Shallow Concentrated Flow, Shallow Concen #2 Nearly Bare & Untilled Kv= 10.0 fps 7.1 325 Total Subcatchment 1S: Existing Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)2 1 0 Type III 24-hr 50 year Rainfall=6.30" Runoff Area=28,300 sf Runoff Volume=0.163 af Runoff Depth>3.01" Flow Length=325' Tc=7.1 min CN=72 2.34 cfs Existing - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 100 year Rainfall=7.10"Existing 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 8HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing Runoff =2.83 cfs @ 12.11 hrs, Volume=0.198 af, Depth>3.65" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100 year Rainfall=7.10" Area (sf)CN Description 10,300 60 Woods, Fair, HSG B 18,000 79 <50% Grass cover, Poor, HSG B 28,300 72 Weighted Average 28,300 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 4.6 30 0.0800 0.11 Sheet Flow, Sheet Flow Woods: Light underbrush n= 0.400 P2= 3.35" 0.4 120 0.8000 4.47 Shallow Concentrated Flow, #1 Shallow conc Woodland Kv= 5.0 fps 2.1 175 0.0200 1.41 Shallow Concentrated Flow, Shallow Concen #2 Nearly Bare & Untilled Kv= 10.0 fps 7.1 325 Total Subcatchment 1S: Existing Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)3 2 1 0 Type III 24-hr 100 year Rainfall=7.10" Runoff Area=28,300 sf Runoff Volume=0.198 af Runoff Depth>3.65" Flow Length=325' Tc=7.1 min CN=72 2.83 cfs 2S Proposed 5R Rip Rap Level spreader 4P 4X4 Galleys 6P OutFall Routing Diagram for Proposed 26 Platoz Dr Prepared by May Engineering, LLC Timothy May, PE, Printed 12/26/2023 HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Subcat Reach Pond Link Proposed - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Proposed 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 2HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 0.210 61 >75% Grass cover, Good, HSG B (2S) 0.194 98 Pavedside wlks paved drive / roof to infiltrations, 50% imp, HSG A (2S) 0.246 55 Woods, Good, HSG B (2S) 0.650 70 TOTAL AREA Proposed - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 2-year Rainfall=3.40"Proposed 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 3HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Runoff =0.51 cfs @ 12.21 hrs, Volume=0.046 af, Depth>0.85" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-year Rainfall=3.40" Area (sf)CN Description *8,467 98 Pavedside wlks paved drive / roof to infiltrations, 50% imp, HSG A 9,133 61 >75% Grass cover, Good, HSG B 10,700 55 Woods, Good, HSG B 28,300 70 Weighted Average 24,067 85.04% Pervious Area 4,234 14.96% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 4.6 30 0.0800 0.11 Sheet Flow, Sheet Woods: Light underbrush n= 0.400 P2= 3.35" 2.2 145 0.0500 1.12 Shallow Concentrated Flow, #1 Shallow Woodland Kv= 5.0 fps 5.4 160 0.0050 0.49 Shallow Concentrated Flow, #2 Shallow conc Short Grass Pasture Kv= 7.0 fps 1.1 110 0.0600 1.71 Shallow Concentrated Flow, Shallow #3 Short Grass Pasture Kv= 7.0 fps 13.3 445 Total Proposed - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 2-year Rainfall=3.40"Proposed 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 4HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Subcatchment 2S: Proposed Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)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=3.40" Runoff Area=28,300 sf Runoff Volume=0.046 af Runoff Depth>0.85" Flow Length=445' Tc=13.3 min CN=70 0.51 cfs Proposed - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 5 year Rainfall=4.30"Proposed 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 5HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Runoff =0.88 cfs @ 12.20 hrs, Volume=0.076 af, Depth>1.40" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 5 year Rainfall=4.30" Area (sf)CN Description *8,467 98 Pavedside wlks paved drive / roof to infiltrations, 50% imp, HSG A 9,133 61 >75% Grass cover, Good, HSG B 10,700 55 Woods, Good, HSG B 28,300 70 Weighted Average 24,067 85.04% Pervious Area 4,234 14.96% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 4.6 30 0.0800 0.11 Sheet Flow, Sheet Woods: Light underbrush n= 0.400 P2= 3.35" 2.2 145 0.0500 1.12 Shallow Concentrated Flow, #1 Shallow Woodland Kv= 5.0 fps 5.4 160 0.0050 0.49 Shallow Concentrated Flow, #2 Shallow conc Short Grass Pasture Kv= 7.0 fps 1.1 110 0.0600 1.71 Shallow Concentrated Flow, Shallow #3 Short Grass Pasture Kv= 7.0 fps 13.3 445 Total Proposed - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 5 year Rainfall=4.30"Proposed 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 6HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Subcatchment 2S: Proposed Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 5 year Rainfall=4.30" Runoff Area=28,300 sf Runoff Volume=0.076 af Runoff Depth>1.40" Flow Length=445' Tc=13.3 min CN=70 0.88 cfs Proposed - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 10 year Rainfall=4.80"Proposed 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 7HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Runoff =1.10 cfs @ 12.20 hrs, Volume=0.094 af, Depth>1.73" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10 year Rainfall=4.80" Area (sf)CN Description *8,467 98 Pavedside wlks paved drive / roof to infiltrations, 50% imp, HSG A 9,133 61 >75% Grass cover, Good, HSG B 10,700 55 Woods, Good, HSG B 28,300 70 Weighted Average 24,067 85.04% Pervious Area 4,234 14.96% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 4.6 30 0.0800 0.11 Sheet Flow, Sheet Woods: Light underbrush n= 0.400 P2= 3.35" 2.2 145 0.0500 1.12 Shallow Concentrated Flow, #1 Shallow Woodland Kv= 5.0 fps 5.4 160 0.0050 0.49 Shallow Concentrated Flow, #2 Shallow conc Short Grass Pasture Kv= 7.0 fps 1.1 110 0.0600 1.71 Shallow Concentrated Flow, Shallow #3 Short Grass Pasture Kv= 7.0 fps 13.3 445 Total Proposed - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 10 year Rainfall=4.80"Proposed 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 8HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Subcatchment 2S: Proposed Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)1 0 Type III 24-hr 10 year Rainfall=4.80" Runoff Area=28,300 sf Runoff Volume=0.094 af Runoff Depth>1.73" Flow Length=445' Tc=13.3 min CN=70 1.10 cfs Proposed - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 25 year Rainfall=5.70"Proposed 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 9HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Runoff =1.52 cfs @ 12.19 hrs, Volume=0.128 af, Depth>2.37" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 25 year Rainfall=5.70" Area (sf)CN Description *8,467 98 Pavedside wlks paved drive / roof to infiltrations, 50% imp, HSG A 9,133 61 >75% Grass cover, Good, HSG B 10,700 55 Woods, Good, HSG B 28,300 70 Weighted Average 24,067 85.04% Pervious Area 4,234 14.96% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 4.6 30 0.0800 0.11 Sheet Flow, Sheet Woods: Light underbrush n= 0.400 P2= 3.35" 2.2 145 0.0500 1.12 Shallow Concentrated Flow, #1 Shallow Woodland Kv= 5.0 fps 5.4 160 0.0050 0.49 Shallow Concentrated Flow, #2 Shallow conc Short Grass Pasture Kv= 7.0 fps 1.1 110 0.0600 1.71 Shallow Concentrated Flow, Shallow #3 Short Grass Pasture Kv= 7.0 fps 13.3 445 Total Proposed - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 25 year Rainfall=5.70"Proposed 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 10HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Subcatchment 2S: Proposed Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)1 0 Type III 24-hr 25 year Rainfall=5.70" Runoff Area=28,300 sf Runoff Volume=0.128 af Runoff Depth>2.37" Flow Length=445' Tc=13.3 min CN=70 1.52 cfs Proposed - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 50 year Rainfall=6.30"Proposed 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 11HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Runoff =1.81 cfs @ 12.19 hrs, Volume=0.152 af, Depth>2.82" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 50 year Rainfall=6.30" Area (sf)CN Description *8,467 98 Pavedside wlks paved drive / roof to infiltrations, 50% imp, HSG A 9,133 61 >75% Grass cover, Good, HSG B 10,700 55 Woods, Good, HSG B 28,300 70 Weighted Average 24,067 85.04% Pervious Area 4,234 14.96% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 4.6 30 0.0800 0.11 Sheet Flow, Sheet Woods: Light underbrush n= 0.400 P2= 3.35" 2.2 145 0.0500 1.12 Shallow Concentrated Flow, #1 Shallow Woodland Kv= 5.0 fps 5.4 160 0.0050 0.49 Shallow Concentrated Flow, #2 Shallow conc Short Grass Pasture Kv= 7.0 fps 1.1 110 0.0600 1.71 Shallow Concentrated Flow, Shallow #3 Short Grass Pasture Kv= 7.0 fps 13.3 445 Total Proposed - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 50 year Rainfall=6.30"Proposed 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 12HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Subcatchment 2S: Proposed Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)2 1 0 Type III 24-hr 50 year Rainfall=6.30" Runoff Area=28,300 sf Runoff Volume=0.152 af Runoff Depth>2.82" Flow Length=445' Tc=13.3 min CN=70 1.81 cfs Proposed - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 100 year Rainfall=7.10"Proposed 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 13HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Proposed Runoff =2.21 cfs @ 12.19 hrs, Volume=0.186 af, Depth>3.43" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100 year Rainfall=7.10" Area (sf)CN Description *8,467 98 Pavedside wlks paved drive / roof to infiltrations, 50% imp, HSG A 9,133 61 >75% Grass cover, Good, HSG B 10,700 55 Woods, Good, HSG B 28,300 70 Weighted Average 24,067 85.04% Pervious Area 4,234 14.96% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 4.6 30 0.0800 0.11 Sheet Flow, Sheet Woods: Light underbrush n= 0.400 P2= 3.35" 2.2 145 0.0500 1.12 Shallow Concentrated Flow, #1 Shallow Woodland Kv= 5.0 fps 5.4 160 0.0050 0.49 Shallow Concentrated Flow, #2 Shallow conc Short Grass Pasture Kv= 7.0 fps 1.1 110 0.0600 1.71 Shallow Concentrated Flow, Shallow #3 Short Grass Pasture Kv= 7.0 fps 13.3 445 Total Proposed - 26 Platoz Dr., Uncasville, CTC:\Program Files (x86)\HydroCAD\Projects\ Type III 24-hr 100 year Rainfall=7.10"Proposed 26 Platoz Dr Printed 12/26/2023Prepared by May Engineering, LLC Timothy May, PE Page 14HydroCAD® 10.00-22 s/n 03977 © 2018 HydroCAD Software Solutions LLC Subcatchment 2S: Proposed Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)2 1 0 Type III 24-hr 100 year Rainfall=7.10" Runoff Area=28,300 sf Runoff Volume=0.186 af Runoff Depth>3.43" Flow Length=445' Tc=13.3 min CN=70 2.21 cfs