Burlington, Massachusetts

Transcription

1 Stormwater Management Summary Proposed Restaurant Burlington, Massachusetts Prepared for ND Burlington South Avenue LLC C/O National Development 2310 Washington Street Newton, MA Prepared by /Vanasse Hangen Brustlin, Inc. Transportation, Land Development, Environmental Services 101 Walnut Street P.O. Box 9151 Watertown, Massachusetts Date: March 13, 2015

2 March 13, 2015 Ref: Mr. Larry Cohen, Chair Burlington Conservation Commission Conservation Department 25 Center Street Burlington, MA Re: Stormwater Management Summary 15 South Avenue Proposed Restaurant MassDEP File # Dear Mr. Cohen and Commissioners, VHB is providing this letter in support of the request for an amended Order of Conditions (OOC) for the above referenced Notice of Intent (NOI) filing to document the revisions to the proposed stormwater management design for the 15 South Avenue site (the Site). The previously proposed stormwater management design for the restaurant parcel was prepared in accordance with the DEP Stormwater Regulations. The revised design, presented in the March 13, 2015 plans and the attached supporting documentation (the Revised Design), includes the same water quality and quantity BMPs as the approved plan, and will function in a consistent manner to the approved design and will continue to comply with the DEP Stormwater Management Regulations. The project will also continue to remove more than half of an acre of impervious coverage as compared to the existing conditions. Proposed Stormwater Design With the Revised Design, the building is located closer to South Avenue, and the adjacent parking area is consolidated into a more efficient layout on two sides of the building. The entry drive from South Avenue is realigned and an adjacent sidewalk added to respond to Planning Board comments and requirements of the Site Plan Approval in Because the parking area adjacent to the building is more efficient, fewer parking spaces are proposed on the outer parking lot to achieve the previously approved parking count. As shown on the attached Figure 3 (revised), Proposed Drainage Areas, stormwater from the entry drive, building and adjacent parking area will continue to be collected in deep sump catch basins with hoods, routed through a water quality unit and discharged to an extended detention basin (Detention Basin 3P). This detention basin (Pond 3P in the figure) is larger in footprint than the previously approved design, and is constructed with more gentle slopes. Access for maintenance to Detention Basin 3P is \\Vhb\proj\Wat-LD\ \docs\letters\Stormwater-BWW\ Revised Stormwater Analysis Letter.docx

3 Larry Cohen, Chair Ref: March 13, 2015 Page 2 provided via a gentle 5:1 slope adjacent to the retaining wall and is accessed by a gate along the main entry drive and upper parking lot drive. Runoff from the upper parking lot is tributary to the proposed bioretention basin. No changes are made to the proposed bioretention basin, except that the water will enter the basin s forebay via overland flow through a channel rather than through a catch basin / piped connection. The bioretention basin has not changed in size because the design includes capacity for a potential future parking expansion of nine spaces in the location shown on Figure 3 (Revised). The drainage system design and hydrologic rate tables presented herein include the impervious coverage associated with these nine potential future parking spaces, however should the tenant or owner desire to expand this parking area in the future, approvals would be required from both the Planning Board and the Conservation Commission. A total suspended solids (TSS) removal of 80% or more will continue to be achieved in compliance with the DEP Stormwater Regulations. Updated TSS removal calculations, water quality volume calculations for the stormwater BMPs, and closed drainage calculations are provided as attachments. Cinema Drainage The one new element in the drainage design which was not part of the 2013 Order of Conditions is the partial relocation of the existing subsurface detention system which serves only the Cinema parcel but is actually located on the Restaurant parcel. The system is labeled as Cinema Subsurface Detention System on the plans. The existing system is comprised of two 12 perforated HDPE pipes in a 20 ft wide x 175 ft long x 18 inch deep filter stone trench with non-woven filter fabric which takes stormwater from the basin on the Cinema side of South Ave, provides some additional detention, and discharges the water to the South Ave drainage system. In its reconfigured form, half of the existing system will remain in place. The half that is to be removed will be replicated immediately adjacent to the existing stone trench to remain on either side. The resulting relocation will provide a new system that is 90 feet long x 40 feet wide x 18 inches deep. There will be new header pipes installed on the upstream and downstream ends of the system. The volume will be the same or greater than the existing system and will continue to function as it does presently. It will remain entirely separate from the restaurant parcel stormwater management system and will discharge from the site in the same location it does today. Hydrologic Analysis From a hydrologic standpoint the Revised Design is consistent with the approved design and in many cases the peak rates are further reduced. The approved design included dramatically reducing overland flow across an adjacent parking lot to Existing Basin 2 by routing the detention basin discharge to the Existing Basin 1A/Wetland 1 outfall. The revised design retains this configuration and due to the \\Vhb\proj\Wat-LD\ \docs\letters\Stormwater-BWW\ Revised Stormwater Analysis Letter.docx

4 Larry Cohen, Chair Ref: March 13, 2015 Page 3 increased size of Detention Basin 3P, the rate of stormwater tributary to this location is further reduced, as is the rate of discharge to Wetland 1. The following table presents the results of the existing, previously proposed and currently proposed hydrologic analysis. Table 1 Peak Discharge Rates (cfs*) Design Point 2-year 10-year 25-year 100-year Design Point: Design Point 1 (Basin 1A) Existing Previously Proposed Currently Proposed Design Point: Design Point 2 (South Property Boundary) Existing Previously Proposed Currently Proposed Design Point: Design Point 3 (Southeast Property Boundary) Existing Previously Proposed Currently Proposed Design Point: Design Point 4 (Northeast Property Boundary) Existing Previously Proposed Currently Proposed Design Point: Design Point 5 (DP 1 and DP2 Combined Wetland 1) Existing Previously Proposed Currently Proposed We trust you find that the information presented herein adequately documents the project s consistency with the approved design, and that the project will continue to comply with the DEP Stormwater Management Regulations. \\Vhb\proj\Wat-LD\ \docs\letters\Stormwater-BWW\ Revised Stormwater Analysis Letter.docx

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9 \\vhb\proj\wat-ld\ \cad\ld\eng\stormwater\12313-drainage-pr_ dwg SOUTH AVE. Vanasse Hangen Brustlin, Inc. Figure 3 03/13/2015 Proposed Conditions Drainage Areas Proposed Restaurant Feet

10 TSS Removal Calculation Worksheet Project Name: AMC Renovations + Restaura Sheet: 1 of 2 Project Number: Date: 17-Sep-2013 Location: Burlington, MA Computed by: MAC Discharge Point: Checked by: KFS Drainage Area(s): 1C+1D A B C D E Vanasse Hangen Brustlin, Inc. Consulting Engineers and Planners 101 Walnut Street Watertown, MA (617) BMP* TSS Removal Rate* Starting TSS Load** Amount Removed (B*C) Remaining Load (D-E) Deep Sump and Hooded Catch Basin 25% Stormceptor - STC % Extended Dry Detention Basin 50% % % * BMP and TSS Removal Rate Values from the MassDEP Stormwater Handbook Vol. 1. Removal rates for proprietary devices are from approved studies and/or manufacturer data (attach study or data source, or remove this sentence if not applicable). ** Equals remaining load from previous BMP (E) *** Stormceptor sizing calculation gives a TSS removal rate of 87%. To be conservative, 50% removal is used for this calculation based upon the NJCAT study provided on the MA STEP website. Backup documentation to support TSS removal rate from the MA STEP website has been provided. Treatment Train TSS Removal = 81% \\Vhb\proj\Wat-LD\ \docs\letters\Stormwater-BWW\attachments\TSS Removal Worksheet.xls

11 TSS Removal Calculation Worksheet Project Name: AMC Renovations + Restaura Sheet: 2 of 2 Project Number: Date: 17-Sep-2013 Location: Burlington, MA Computed by: MAC Discharge Point: 1A Checked by: KFS Drainage Area(s): 1 A B C D E Vanasse Hangen Brustlin, Inc. Consulting Engineers and Planners 101 Walnut Street Watertown, MA (617) BMP* TSS Removal Rate* Starting TSS Load** Amount Removed (B*C) Remaining Load (D-E) Bioretention Area 90% % % % % * BMP and TSS Removal Rate Values from the MassDEP Stormwater Handbook Vol. ** Equals remaining load from previous BMP (E) Treatment Train TSS Removal = 90% \\Vhb\proj\Wat-LD\ \docs\letters\Stormwater-BWW\attachments\TSS Removal Worksheet.xls

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16 VHB Water Quality Volume Calculations Project Name: Outparcel Restaurant Proj. No.: Project Location: Burlington, MA Date: 3/12/2015 Calculated by: RPM Bioretention Basin (Runoff from Area PR-1A) Total Impervious Area = 0.33 Acres Required: Runoff Depth to be Treated (in.) Required Volume (c.f.) Forebay Volume Water Quality Volume 1 1,198 Provided: Sediment Forebay Elevation Area (s.f.) Cumulative Volume (c.f.) Cumulative Bioretention Basin Elevation Area (s.f.) Volume (c.f.) , ,990 1,434 Bioretention Basin Summary Sediment Forebay Storage Volume Required (c.f.) = 120 Sediment Forebay Storage Volume Provided (c.f.) = 978 Water Quality Storage Volume Required (c.f.) = 1,198 Water Quality Storage Volume Provided (c.f.) = 1,434 Extended Dry Detention Basin (Runoff from PR-1C) *Pretreatment provided with Stormceptor Unit Total Impervious Area = 1.30 Required: Runoff Depth to be Treated (in.) Required Volume (c.f.) Forebay Volume Water Quality Volume 1 4,724 Provided: Sediment Forebay Elevation Area (s.f.) Cumulative Volume (c.f.) Cumulative Extended Detention Basin Elevation Area (s.f.) Volume (c.f.) , ,650 5, ,700 5, ,008 8,231 Detention Basin Summary Sediment Forebay Storage Volume Required (c.f.) = 472 Sediment Forebay Storage Volume Provided (c.f.) = 500 Water Quality Storage Volume Required (c.f.) = 4,724 Water Quality Storage Volume Provided (c.f.) = 8,231 Sheet1\\Vhb\proj\Wat-LD\ \docs\letters\Stormwater-BWW\attachments\Water Quality Volume Analysis.xls

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18 1A Wetlands Area DP1 Basin 1A 5 2R CB 1P 1B Analysis Point #5 (Wetland 1) EX piping 2 Bio-retention West Parking 3P 1C DP2 2P South PR Detention East Parking & Building S Property Boundary South EX Detention 2B South Landscape 2A South Pond Area 3A 4A SE Property Boundary NE Property Boundary DP3 DP4 SE Property Boundary NE Property Boundary Subcat Reach Pond Link Routing Diagram for PR_HydroCAD,

19 Type III 24-hr 2-Year Rainfall=3.10" Page 2 Summary for Subcatchment 1A: Wetlands Area Runoff = hrs, Volume= af, Depth= 1.60" Type III 24-hr 2-Year Rainfall=3.10" 25, % Grass cover, Fair, HSG D 25, % Pervious Area Summary for Subcatchment 1B: West Parking Runoff = hrs, Volume= af, Depth= 2.26" Type III 24-hr 2-Year Rainfall=3.10" 9, % Grass cover, Fair, HSG D 13, Paved parking, HSG D 23, Weighted Average 9, % Pervious Area 13, % Impervious Area Summary for Subcatchment 1C: East Parking & Building Runoff = hrs, Volume= af, Depth= 2.26" Type III 24-hr 2-Year Rainfall=3.10" 54, Paved parking, HSG D 35, % Grass cover, Fair, HSG D 90, Weighted Average 35, % Pervious Area 54, % Impervious Area

20 Type III 24-hr 2-Year Rainfall=3.10" Page 3 Summary for Subcatchment 2A: South Pond Area Runoff = hrs, Volume= af, Depth= 1.60" Type III 24-hr 2-Year Rainfall=3.10" 6, % Grass cover, Fair, HSG D 6, % Pervious Area Summary for Subcatchment 2B: South Landscape Runoff = hrs, Volume= af, Depth= 1.60" Type III 24-hr 2-Year Rainfall=3.10" 3, % Grass cover, Fair, HSG D 3, % Pervious Area Summary for Subcatchment 3A: SE Property Boundary Runoff = hrs, Volume= af, Depth= 1.60" Type III 24-hr 2-Year Rainfall=3.10" 2, % Grass cover, Fair, HSG D 2, % Pervious Area

21 Type III 24-hr 2-Year Rainfall=3.10" Page 4 Summary for Subcatchment 4A: NE Property Boundary Runoff = hrs, Volume= af, Depth= 1.60" Type III 24-hr 2-Year Rainfall=3.10" 1, % Grass cover, Fair, HSG D 1, % Pervious Area Summary for Pond 1P: Bio-retention Inflow Area = ac, 58.06% Impervious, Inflow Depth = 2.26" for 2-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 7%, Lag= 1.9 min Primary = hrs, Volume= af Secondary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 2,280 sf Storage= 1,622 cf Plug-Flow detention time= min calculated for af (65% of inflow) Center-of-Mass det. time= 72.3 min ( ) Volume Invert Avail.Storage Storage Description # ' 4,821 cf Custom Stage Data (Irregular)Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft) , , , ,995 1,995 4, , ,826 4,821 6,080 Device Routing Invert Outlet Devices #1 Primary ' 6.0" Round Culvert L= 60.0' CPP, square edge headwall, Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= PVC, smooth interior, Flow Area= 0.20 sf #2 Device ' 2.3" x 2.3" Horiz. Orifice/Grate X 8.00 columns X 8 rows C= Limited to weir flow at low heads #3 Secondary ' 15.0' long x 5.0' breadth Broad-Crested Rectangular Weir

22 Type III 24-hr 2-Year Rainfall=3.10" Page 5 Head (feet) Coef. (English) Primary OutFlow Max= hrs HW=182.84' TW=170.24' (Dynamic Tailwater) 1=Culvert (Passes 1.34 cfs of 1.51 cfs potential flow) 2=Orifice/Grate (Weir Controls fps) Secondary OutFlow Max= hrs HW=182.00' TW=0.00' (Dynamic Tailwater) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond 2P: South EX Detention Inflow Area = ac, 0.00% Impervious, Inflow Depth > 5.62" for 2-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 76%, Lag= 28.9 min Discarded = hrs, Volume= af Primary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 994 sf Storage= 371 cf Plug-Flow detention time= 42.4 min calculated for af (98% of inflow) Center-of-Mass det. time= 31.4 min ( 1, ,053.8 ) Volume Invert Avail.Storage Storage Description # ' 997 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) , , Device Routing Invert Outlet Devices #1 Primary ' 50.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) Coef. (English) #2 Discarded ' in/hr Exfiltration over Surface area Discarded OutFlow Max= hrs HW=166.72' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.08 cfs) Primary OutFlow Max= hrs HW=166.00' TW=0.00' (Dynamic Tailwater) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

23 Type III 24-hr 2-Year Rainfall=3.10" Page 6 Summary for Pond 2R: EX piping 2 Inflow Area = ac, 59.74% Impervious, Inflow Depth = 0.99" for 2-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Device Routing Invert Outlet Devices #1 Primary ' 18.0" Round Culvert L= 30.0' Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.013, Flow Area= 1.77 sf Primary OutFlow Max= hrs HW=170.24' TW=0.00' (Dynamic Tailwater) 1=Culvert (Barrel Controls fps) Summary for Pond 3P: South PR Detention Inflow Area = ac, 60.17% Impervious, Inflow Depth = 2.26" for 2-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 92%, Lag= 57.6 min Primary = hrs, Volume= af Secondary = hrs, Volume= af Tertiary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 6,373 sf Storage= 10,125 cf Plug-Flow detention time= min calculated for af (52% of inflow) Center-of-Mass det. time= min ( 1, ) Volume Invert Avail.Storage Storage Description # ' 30,031 cf Detention pond 1 (Prismatic)Listed below (Recalc) #2A ' 128 cf 2.58'W x 62.00'L x 2.08'H Field A 334 cf Overall - 15 cf Embedded = 319 cf x 40.0% Voids #3A ' 15 cf CPP 6 x 3 Inside #2 Inside= 6.0"W x 6.0"H => 0.24 sf x 20.00'L = 4.8 cf Outside= 7.0"W x 7.0"H => 0.24 sf x 20.00'L = 4.8 cf 30,173 cf Total Available Storage Storage Group A created with Chamber Wizard

24 Type III 24-hr 2-Year Rainfall=3.10" Page 7 Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) , ,650 5,322 5, ,366 6,008 11, ,118 6,742 18, ,075 7,597 25, ,376 4,363 30,031 Device Routing Invert Outlet Devices #1 Primary ' 18.0" Round Culvert L= 215.0' RCP, sq.cut end projecting, Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.013, Flow Area= 1.77 sf #2 Secondary ' 6.0" Round Culvert L= 47.0' CPP, square edge headwall, Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= Concrete pipe, straight & clean, Flow Area= 0.20 sf #3 Device ' 18.0" Vert. Orifice/Grate C= #4 Device ' 0.8" Vert. Orifice/Grate C= #5 Tertiary ' 20.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) Coef. (English) #6 Device ' 24.0" Horiz. Orifice/Grate C= Limited to weir flow at low heads Primary OutFlow Max= hrs HW=172.79' TW=169.99' (Dynamic Tailwater) 1=Culvert (Passes 0.43 cfs of 0.76 cfs potential flow) 3=Orifice/Grate (Orifice Controls fps) 6=Orifice/Grate ( Controls 0.00 cfs) Secondary OutFlow Max= hrs HW=172.79' TW=166.70' (Dynamic Tailwater) 2=Culvert (Passes 0.03 cfs of 1.87 cfs potential flow) 4=Orifice/Grate (Orifice Controls fps) Tertiary OutFlow Max= hrs HW=169.00' TW=166.00' (Dynamic Tailwater) 5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Link 5: Analysis Point #5 (Wetland 1) Inflow Area = ac, 45.42% Impervious, Inflow Depth = 1.07" for 2-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs

25 Type III 24-hr 2-Year Rainfall=3.10" Page 8 Summary for Link DP1: Basin 1A Inflow Area = ac, 48.76% Impervious, Inflow Depth = 1.10" for 2-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs Summary for Link DP2: S Property Boundary Inflow Area = ac, 0.00% Impervious, Inflow Depth = 0.53" for 2-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs Summary for Link DP3: SE Property Boundary Inflow Area = ac, 0.00% Impervious, Inflow Depth = 1.60" for 2-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs Summary for Link DP4: NE Property Boundary Inflow Area = ac, 0.00% Impervious, Inflow Depth = 1.60" for 2-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs

26 Type III 24-hr 10-Year Rainfall=4.50" Page 9 Summary for Subcatchment 1A: Wetlands Area Runoff = hrs, Volume= af, Depth= 2.82" Type III 24-hr 10-Year Rainfall=4.50" 25, % Grass cover, Fair, HSG D 25, % Pervious Area Summary for Subcatchment 1B: West Parking Runoff = hrs, Volume= af, Depth= 3.60" Type III 24-hr 10-Year Rainfall=4.50" 9, % Grass cover, Fair, HSG D 13, Paved parking, HSG D 23, Weighted Average 9, % Pervious Area 13, % Impervious Area Summary for Subcatchment 1C: East Parking & Building Runoff = hrs, Volume= af, Depth= 3.60" Type III 24-hr 10-Year Rainfall=4.50" 54, Paved parking, HSG D 35, % Grass cover, Fair, HSG D 90, Weighted Average 35, % Pervious Area 54, % Impervious Area

27 Type III 24-hr 10-Year Rainfall=4.50" Page 10 Summary for Subcatchment 2A: South Pond Area Runoff = hrs, Volume= af, Depth= 2.82" Type III 24-hr 10-Year Rainfall=4.50" 6, % Grass cover, Fair, HSG D 6, % Pervious Area Summary for Subcatchment 2B: South Landscape Runoff = hrs, Volume= af, Depth= 2.82" Type III 24-hr 10-Year Rainfall=4.50" 3, % Grass cover, Fair, HSG D 3, % Pervious Area Summary for Subcatchment 3A: SE Property Boundary Runoff = hrs, Volume= af, Depth= 2.82" Type III 24-hr 10-Year Rainfall=4.50" 2, % Grass cover, Fair, HSG D 2, % Pervious Area

28 Type III 24-hr 10-Year Rainfall=4.50" Page 11 Summary for Subcatchment 4A: NE Property Boundary Runoff = hrs, Volume= af, Depth= 2.82" Type III 24-hr 10-Year Rainfall=4.50" 1, % Grass cover, Fair, HSG D 1, % Pervious Area Summary for Pond 1P: Bio-retention Inflow Area = ac, 58.06% Impervious, Inflow Depth = 3.60" for 10-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 32%, Lag= 4.7 min Primary = hrs, Volume= af Secondary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 2,373 sf Storage= 1,864 cf Plug-Flow detention time= min calculated for af (78% of inflow) Center-of-Mass det. time= 52.0 min ( ) Volume Invert Avail.Storage Storage Description # ' 4,821 cf Custom Stage Data (Irregular)Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft) , , , ,995 1,995 4, , ,826 4,821 6,080 Device Routing Invert Outlet Devices #1 Primary ' 6.0" Round Culvert L= 60.0' CPP, square edge headwall, Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= PVC, smooth interior, Flow Area= 0.20 sf #2 Device ' 2.3" x 2.3" Horiz. Orifice/Grate X 8.00 columns X 8 rows C= Limited to weir flow at low heads #3 Secondary ' 15.0' long x 5.0' breadth Broad-Crested Rectangular Weir

29 Type III 24-hr 10-Year Rainfall=4.50" Page 12 Head (feet) Coef. (English) Primary OutFlow Max= hrs HW=182.95' TW=170.65' (Dynamic Tailwater) 1=Culvert (Barrel Controls fps) 2=Orifice/Grate (Passes 1.53 cfs of 4.32 cfs potential flow) Secondary OutFlow Max= hrs HW=182.00' TW=0.00' (Dynamic Tailwater) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond 2P: South EX Detention Inflow Area = ac, 0.00% Impervious, Inflow Depth > 7.12" for 10-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 81%, Lag= 30.2 min Discarded = hrs, Volume= af Primary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 1,350 sf Storage= 685 cf Plug-Flow detention time= 56.0 min calculated for af (99% of inflow) Center-of-Mass det. time= 46.6 min ( 1, ) Volume Invert Avail.Storage Storage Description # ' 997 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) , , Device Routing Invert Outlet Devices #1 Primary ' 50.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) Coef. (English) #2 Discarded ' in/hr Exfiltration over Surface area Discarded OutFlow Max= hrs HW=166.99' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.11 cfs) Primary OutFlow Max= hrs HW=166.00' TW=0.00' (Dynamic Tailwater) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

30 Type III 24-hr 10-Year Rainfall=4.50" Page 13 Summary for Pond 2R: EX piping 2 Inflow Area = ac, 59.74% Impervious, Inflow Depth = 2.32" for 10-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Device Routing Invert Outlet Devices #1 Primary ' 18.0" Round Culvert L= 30.0' Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.013, Flow Area= 1.77 sf Primary OutFlow Max= hrs HW=170.81' TW=0.00' (Dynamic Tailwater) 1=Culvert (Barrel Controls fps) Summary for Pond 3P: South PR Detention Inflow Area = ac, 60.17% Impervious, Inflow Depth = 3.60" for 10-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 69%, Lag= 17.8 min Primary = hrs, Volume= af Secondary = hrs, Volume= af Tertiary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 6,719 sf Storage= 13,131 cf Plug-Flow detention time= min calculated for af (70% of inflow) Center-of-Mass det. time= min ( ) Volume Invert Avail.Storage Storage Description # ' 30,031 cf Detention pond 1 (Prismatic)Listed below (Recalc) #2A ' 128 cf 2.58'W x 62.00'L x 2.08'H Field A 334 cf Overall - 15 cf Embedded = 319 cf x 40.0% Voids #3A ' 15 cf CPP 6 x 3 Inside #2 Inside= 6.0"W x 6.0"H => 0.24 sf x 20.00'L = 4.8 cf Outside= 7.0"W x 7.0"H => 0.24 sf x 20.00'L = 4.8 cf 30,173 cf Total Available Storage Storage Group A created with Chamber Wizard

31 Type III 24-hr 10-Year Rainfall=4.50" Page 14 Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) , ,650 5,322 5, ,366 6,008 11, ,118 6,742 18, ,075 7,597 25, ,376 4,363 30,031 Device Routing Invert Outlet Devices #1 Primary ' 18.0" Round Culvert L= 215.0' RCP, sq.cut end projecting, Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.013, Flow Area= 1.77 sf #2 Secondary ' 6.0" Round Culvert L= 47.0' CPP, square edge headwall, Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= Concrete pipe, straight & clean, Flow Area= 0.20 sf #3 Device ' 18.0" Vert. Orifice/Grate C= #4 Device ' 0.8" Vert. Orifice/Grate C= #5 Tertiary ' 20.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) Coef. (English) #6 Device ' 24.0" Horiz. Orifice/Grate C= Limited to weir flow at low heads Primary OutFlow Max= hrs HW=173.26' TW=170.68' (Dynamic Tailwater) 1=Culvert (Passes 2.65 cfs of 3.29 cfs potential flow) 3=Orifice/Grate (Orifice Controls fps) 6=Orifice/Grate ( Controls 0.00 cfs) Secondary OutFlow Max= hrs HW=173.26' TW=166.96' (Dynamic Tailwater) 2=Culvert (Passes 0.03 cfs of 1.94 cfs potential flow) 4=Orifice/Grate (Orifice Controls fps) Tertiary OutFlow Max= hrs HW=169.00' TW=166.00' (Dynamic Tailwater) 5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Link 5: Analysis Point #5 (Wetland 1) Inflow Area = ac, 45.42% Impervious, Inflow Depth = 2.31" for 10-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs

32 Type III 24-hr 10-Year Rainfall=4.50" Page 15 Summary for Link DP1: Basin 1A Inflow Area = ac, 48.76% Impervious, Inflow Depth = 2.41" for 10-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs Summary for Link DP2: S Property Boundary Inflow Area = ac, 0.00% Impervious, Inflow Depth = 0.94" for 10-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs Summary for Link DP3: SE Property Boundary Inflow Area = ac, 0.00% Impervious, Inflow Depth = 2.82" for 10-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs Summary for Link DP4: NE Property Boundary Inflow Area = ac, 0.00% Impervious, Inflow Depth = 2.82" for 10-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs

33 Type III 24-hr 25-Year Rainfall=5.30" Page 16 Summary for Subcatchment 1A: Wetlands Area Runoff = hrs, Volume= af, Depth= 3.55" Type III 24-hr 25-Year Rainfall=5.30" 25, % Grass cover, Fair, HSG D 25, % Pervious Area Summary for Subcatchment 1B: West Parking Runoff = hrs, Volume= af, Depth= 4.38" Type III 24-hr 25-Year Rainfall=5.30" 9, % Grass cover, Fair, HSG D 13, Paved parking, HSG D 23, Weighted Average 9, % Pervious Area 13, % Impervious Area Summary for Subcatchment 1C: East Parking & Building Runoff = hrs, Volume= af, Depth= 4.38" Type III 24-hr 25-Year Rainfall=5.30" 54, Paved parking, HSG D 35, % Grass cover, Fair, HSG D 90, Weighted Average 35, % Pervious Area 54, % Impervious Area

34 Type III 24-hr 25-Year Rainfall=5.30" Page 17 Summary for Subcatchment 2A: South Pond Area Runoff = hrs, Volume= af, Depth= 3.55" Type III 24-hr 25-Year Rainfall=5.30" 6, % Grass cover, Fair, HSG D 6, % Pervious Area Summary for Subcatchment 2B: South Landscape Runoff = hrs, Volume= af, Depth= 3.55" Type III 24-hr 25-Year Rainfall=5.30" 3, % Grass cover, Fair, HSG D 3, % Pervious Area Summary for Subcatchment 3A: SE Property Boundary Runoff = hrs, Volume= af, Depth= 3.55" Type III 24-hr 25-Year Rainfall=5.30" 2, % Grass cover, Fair, HSG D 2, % Pervious Area

35 Type III 24-hr 25-Year Rainfall=5.30" Page 18 Summary for Subcatchment 4A: NE Property Boundary Runoff = hrs, Volume= af, Depth= 3.55" Type III 24-hr 25-Year Rainfall=5.30" 1, % Grass cover, Fair, HSG D 1, % Pervious Area Summary for Pond 1P: Bio-retention Inflow Area = ac, 58.06% Impervious, Inflow Depth = 4.38" for 25-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 43%, Lag= 6.2 min Primary = hrs, Volume= af Secondary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 2,455 sf Storage= 2,096 cf Plug-Flow detention time= min calculated for af (82% of inflow) Center-of-Mass det. time= 48.1 min ( ) Volume Invert Avail.Storage Storage Description # ' 4,821 cf Custom Stage Data (Irregular)Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft) , , , ,995 1,995 4, , ,826 4,821 6,080 Device Routing Invert Outlet Devices #1 Primary ' 6.0" Round Culvert L= 60.0' CPP, square edge headwall, Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= PVC, smooth interior, Flow Area= 0.20 sf #2 Device ' 2.3" x 2.3" Horiz. Orifice/Grate X 8.00 columns X 8 rows C= Limited to weir flow at low heads #3 Secondary ' 15.0' long x 5.0' breadth Broad-Crested Rectangular Weir

36 Type III 24-hr 25-Year Rainfall=5.30" Page 19 Head (feet) Coef. (English) Primary OutFlow Max= hrs HW=183.04' TW=171.08' (Dynamic Tailwater) 1=Culvert (Barrel Controls fps) 2=Orifice/Grate (Passes 1.54 cfs of 5.56 cfs potential flow) Secondary OutFlow Max= hrs HW=182.00' TW=0.00' (Dynamic Tailwater) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond 2P: South EX Detention Inflow Area = ac, 0.00% Impervious, Inflow Depth > 7.97" for 25-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 52%, Lag= 10.1 min Discarded = hrs, Volume= af Primary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 1,382 sf Storage= 721 cf Plug-Flow detention time= 56.5 min calculated for af (99% of inflow) Center-of-Mass det. time= 47.7 min ( 1, ) Volume Invert Avail.Storage Storage Description # ' 997 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) , , Device Routing Invert Outlet Devices #1 Primary ' 50.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) Coef. (English) #2 Discarded ' in/hr Exfiltration over Surface area Discarded OutFlow Max= hrs HW=167.01' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.11 cfs) Primary OutFlow Max= hrs HW=167.01' TW=0.00' (Dynamic Tailwater) 1=Broad-Crested Rectangular Weir (Weir Controls fps)

37 Type III 24-hr 25-Year Rainfall=5.30" Page 20 Summary for Pond 2R: EX piping 2 Inflow Area = ac, 59.74% Impervious, Inflow Depth = 3.09" for 25-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Device Routing Invert Outlet Devices #1 Primary ' 18.0" Round Culvert L= 30.0' Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.013, Flow Area= 1.77 sf Primary OutFlow Max= hrs HW=171.12' TW=0.00' (Dynamic Tailwater) 1=Culvert (Barrel Controls fps) Summary for Pond 3P: South PR Detention Inflow Area = ac, 60.17% Impervious, Inflow Depth = 4.38" for 25-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 59%, Lag= 11.5 min Primary = hrs, Volume= af Secondary = hrs, Volume= af Tertiary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 6,896 sf Storage= 14,698 cf Plug-Flow detention time= min calculated for af (75% of inflow) Center-of-Mass det. time= min ( ) Volume Invert Avail.Storage Storage Description # ' 30,031 cf Detention pond 1 (Prismatic)Listed below (Recalc) #2A ' 128 cf 2.58'W x 62.00'L x 2.08'H Field A 334 cf Overall - 15 cf Embedded = 319 cf x 40.0% Voids #3A ' 15 cf CPP 6 x 3 Inside #2 Inside= 6.0"W x 6.0"H => 0.24 sf x 20.00'L = 4.8 cf Outside= 7.0"W x 7.0"H => 0.24 sf x 20.00'L = 4.8 cf 30,173 cf Total Available Storage Storage Group A created with Chamber Wizard

38 Type III 24-hr 25-Year Rainfall=5.30" Page 21 Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) , ,650 5,322 5, ,366 6,008 11, ,118 6,742 18, ,075 7,597 25, ,376 4,363 30,031 Device Routing Invert Outlet Devices #1 Primary ' 18.0" Round Culvert L= 215.0' RCP, sq.cut end projecting, Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.013, Flow Area= 1.77 sf #2 Secondary ' 6.0" Round Culvert L= 47.0' CPP, square edge headwall, Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= Concrete pipe, straight & clean, Flow Area= 0.20 sf #3 Device ' 18.0" Vert. Orifice/Grate C= #4 Device ' 0.8" Vert. Orifice/Grate C= #5 Tertiary ' 20.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) Coef. (English) #6 Device ' 24.0" Horiz. Orifice/Grate C= Limited to weir flow at low heads Primary OutFlow Max= hrs HW=173.49' TW=171.12' (Dynamic Tailwater) 1=Culvert (Passes 4.21 cfs of 4.91 cfs potential flow) 3=Orifice/Grate (Orifice Controls fps) 6=Orifice/Grate ( Controls 0.00 cfs) Secondary OutFlow Max= hrs HW=173.49' TW=167.01' (Dynamic Tailwater) 2=Culvert (Passes 0.03 cfs of 1.97 cfs potential flow) 4=Orifice/Grate (Orifice Controls fps) Tertiary OutFlow Max= hrs HW=169.00' TW=166.00' (Dynamic Tailwater) 5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Link 5: Analysis Point #5 (Wetland 1) Inflow Area = ac, 45.42% Impervious, Inflow Depth = 3.05" for 25-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs

39 Type III 24-hr 25-Year Rainfall=5.30" Page 22 Summary for Link DP1: Basin 1A Inflow Area = ac, 48.76% Impervious, Inflow Depth = 3.17" for 25-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs Summary for Link DP2: S Property Boundary Inflow Area = ac, 0.00% Impervious, Inflow Depth = 1.41" for 25-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs Summary for Link DP3: SE Property Boundary Inflow Area = ac, 0.00% Impervious, Inflow Depth = 3.55" for 25-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs Summary for Link DP4: NE Property Boundary Inflow Area = ac, 0.00% Impervious, Inflow Depth = 3.55" for 25-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs

40 Type III 24-hr 100-Year Rainfall=6.50" Page 23 Summary for Subcatchment 1A: Wetlands Area Runoff = hrs, Volume= af, Depth= 4.67" Type III 24-hr 100-Year Rainfall=6.50" 25, % Grass cover, Fair, HSG D 25, % Pervious Area Summary for Subcatchment 1B: West Parking Runoff = hrs, Volume= af, Depth= 5.56" Type III 24-hr 100-Year Rainfall=6.50" 9, % Grass cover, Fair, HSG D 13, Paved parking, HSG D 23, Weighted Average 9, % Pervious Area 13, % Impervious Area Summary for Subcatchment 1C: East Parking & Building Runoff = hrs, Volume= af, Depth= 5.56" Type III 24-hr 100-Year Rainfall=6.50" 54, Paved parking, HSG D 35, % Grass cover, Fair, HSG D 90, Weighted Average 35, % Pervious Area 54, % Impervious Area

41 Type III 24-hr 100-Year Rainfall=6.50" Page 24 Summary for Subcatchment 2A: South Pond Area Runoff = hrs, Volume= af, Depth= 4.67" Type III 24-hr 100-Year Rainfall=6.50" 6, % Grass cover, Fair, HSG D 6, % Pervious Area Summary for Subcatchment 2B: South Landscape Runoff = hrs, Volume= af, Depth= 4.67" Type III 24-hr 100-Year Rainfall=6.50" 3, % Grass cover, Fair, HSG D 3, % Pervious Area Summary for Subcatchment 3A: SE Property Boundary Runoff = hrs, Volume= af, Depth= 4.67" Type III 24-hr 100-Year Rainfall=6.50" 2, % Grass cover, Fair, HSG D 2, % Pervious Area

42 Type III 24-hr 100-Year Rainfall=6.50" Page 25 Summary for Subcatchment 4A: NE Property Boundary Runoff = hrs, Volume= af, Depth= 4.67" Type III 24-hr 100-Year Rainfall=6.50" 1, % Grass cover, Fair, HSG D 1, % Pervious Area Summary for Pond 1P: Bio-retention Inflow Area = ac, 58.06% Impervious, Inflow Depth = 5.56" for 100-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 54%, Lag= 8.8 min Primary = hrs, Volume= af Secondary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 2,585 sf Storage= 2,517 cf Plug-Flow detention time= min calculated for af (86% of inflow) Center-of-Mass det. time= 44.8 min ( ) Volume Invert Avail.Storage Storage Description # ' 4,821 cf Custom Stage Data (Irregular)Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft) , , , ,995 1,995 4, , ,826 4,821 6,080 Device Routing Invert Outlet Devices #1 Primary ' 6.0" Round Culvert L= 60.0' CPP, square edge headwall, Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= PVC, smooth interior, Flow Area= 0.20 sf #2 Device ' 2.3" x 2.3" Horiz. Orifice/Grate X 8.00 columns X 8 rows C= Limited to weir flow at low heads #3 Secondary ' 15.0' long x 5.0' breadth Broad-Crested Rectangular Weir

43 Type III 24-hr 100-Year Rainfall=6.50" Page 26 Head (feet) Coef. (English) Primary OutFlow Max= hrs HW=183.21' TW=171.65' (Dynamic Tailwater) 1=Culvert (Barrel Controls fps) 2=Orifice/Grate (Passes 1.58 cfs of 7.23 cfs potential flow) Secondary OutFlow Max= hrs HW=182.00' TW=0.00' (Dynamic Tailwater) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond 2P: South EX Detention Inflow Area = ac, 0.00% Impervious, Inflow Depth > 9.24" for 100-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 11%, Lag= 2.4 min Discarded = hrs, Volume= af Primary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 1,402 sf Storage= 745 cf Plug-Flow detention time= 55.6 min calculated for af (99% of inflow) Center-of-Mass det. time= 47.8 min ( ) Volume Invert Avail.Storage Storage Description # ' 997 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) , , Device Routing Invert Outlet Devices #1 Primary ' 50.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) Coef. (English) #2 Discarded ' in/hr Exfiltration over Surface area Discarded OutFlow Max= hrs HW=167.03' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.11 cfs) Primary OutFlow Max= hrs HW=167.03' TW=0.00' (Dynamic Tailwater) 1=Broad-Crested Rectangular Weir (Weir Controls fps)

44 Type III 24-hr 100-Year Rainfall=6.50" Page 27 Summary for Pond 2R: EX piping 2 Inflow Area = ac, 59.74% Impervious, Inflow Depth = 4.25" for 100-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Device Routing Invert Outlet Devices #1 Primary ' 18.0" Round Culvert L= 30.0' Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.013, Flow Area= 1.77 sf Primary OutFlow Max= hrs HW=171.65' TW=0.00' (Dynamic Tailwater) 1=Culvert (Barrel Controls fps) Summary for Pond 3P: South PR Detention Inflow Area = ac, 60.17% Impervious, Inflow Depth = 5.56" for 100-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 51%, Lag= 7.8 min Primary = hrs, Volume= af Secondary = hrs, Volume= af Tertiary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 7,138 sf Storage= 16,896 cf Plug-Flow detention time= min calculated for af (80% of inflow) Center-of-Mass det. time= 96.3 min ( ) Volume Invert Avail.Storage Storage Description # ' 30,031 cf Detention pond 1 (Prismatic)Listed below (Recalc) #2A ' 128 cf 2.58'W x 62.00'L x 2.08'H Field A 334 cf Overall - 15 cf Embedded = 319 cf x 40.0% Voids #3A ' 15 cf CPP 6 x 3 Inside #2 Inside= 6.0"W x 6.0"H => 0.24 sf x 20.00'L = 4.8 cf Outside= 7.0"W x 7.0"H => 0.24 sf x 20.00'L = 4.8 cf 30,173 cf Total Available Storage Storage Group A created with Chamber Wizard

45 Type III 24-hr 100-Year Rainfall=6.50" Page 28 Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) , ,650 5,322 5, ,366 6,008 11, ,118 6,742 18, ,075 7,597 25, ,376 4,363 30,031 Device Routing Invert Outlet Devices #1 Primary ' 18.0" Round Culvert L= 215.0' RCP, sq.cut end projecting, Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.013, Flow Area= 1.77 sf #2 Secondary ' 6.0" Round Culvert L= 47.0' CPP, square edge headwall, Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= Concrete pipe, straight & clean, Flow Area= 0.20 sf #3 Device ' 18.0" Vert. Orifice/Grate C= #4 Device ' 0.8" Vert. Orifice/Grate C= #5 Tertiary ' 20.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) Coef. (English) #6 Device ' 24.0" Horiz. Orifice/Grate C= Limited to weir flow at low heads Primary OutFlow Max= hrs HW=173.81' TW=171.65' (Dynamic Tailwater) 1=Culvert (Passes 6.40 cfs of 6.99 cfs potential flow) 3=Orifice/Grate (Orifice Controls fps) 6=Orifice/Grate ( Controls 0.00 cfs) Secondary OutFlow Max= hrs HW=173.81' TW=167.02' (Dynamic Tailwater) 2=Culvert (Passes 0.03 cfs of 2.01 cfs potential flow) 4=Orifice/Grate (Orifice Controls fps) Tertiary OutFlow Max= hrs HW=169.00' TW=166.00' (Dynamic Tailwater) 5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Summary for Link 5: Analysis Point #5 (Wetland 1) Inflow Area = ac, 45.42% Impervious, Inflow Depth = 4.18" for 100-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs