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HomeMy WebLinkAbout2024-10-14 Westwood Stormwater Management Plan • 12701 Whitewater Drive,Suite 300 Minnetonka,MN 55343 Westwood Main (952)937-5150 Fax (952)937-5822 westwoodps.com (888)937-5150 MEMORANDUM Date: October 14, 2024 Re: Stormwater Management Plan JACC Capital Holdings—Oak Park Heights,MN File 0044193.00 To: Matt Oldenburg-Downing, Middle St. Croix WMO From: Shari Ahrens, PE This memo summarizes stormwater management plan for the proposed residential development in Oak Park Heights, MN, which is located at 5845 Stagecoach Trail North. Regulatory Requirements The proposed project site falls under the jurisdiction of the City of Oak Park Heights and Middle St. Croix WMO. The following regulations apply: • Rate Control —Limit peak runoff to existing conditions for the 2-, 10-, and 100-year 24-hour storm events. • Volume Reduction—Provide abstraction for 1.1 inches of runoff from impervious surfaces. Existing Site Conditions The 0.34 acre site previously had a metal sided building and paved parking areas. The building and a portion of the pavement has been removed and concrete pavement covers approximately 1/3 of the western portion of the site. Currently the easterly 2/3's of the site is gravel/bituminous filings and is sparsely vegetated. The site gradually slopes easterly and stormwater runoff discharges off the easterly side of the property, down a steep slope to a wetland ditch area located on the west side of Highway 95. Proposed Site Development The proposed development will consist of a three level, 6-unit condo building and parking lot. The majority of the parking will be enclosed in the building with 4 stalls under a building overhang. The building will include green-roof system that covers approximately 50% of the roof area. See Attachment A for the Proposed Drainage Map. RECEIVED OCT 1 t, 2024 Multi-Disciplined Surveying 6(Engineering T3PLs Fvm No.10074302 westwoodps.com Table 1:Impervious Lot Coverage Cover Existing Area [ac] Proposed Area [ac] Impervious 0.11 0.13 Stormwater Management The stormwater drainage will discharge from the drive aisle pavement area to a storm structure and will be routed east to an infiltration basin. The roof area will discharge from the east side of the building to the infiltration basin. There is no on-site storm sewer so the infiltration basin will discharge to the east via a 60-foot long weir. Rate Control Rate control for this site is provided by the infiltration basin. Table 2 shows a summary of runoff rates. A complete summary of the existing and proposed HydroCAD results can be found in Attachments B and C. Table 2:Rate Control Summary Storm Event Existing [cfs] Proposed [cfs] 2-year(2.8") 0.56 0.00 10-year (4.2") 1.10 0.51 100-year (7.3") 2.39 2.31 The 100-yr HWL of the infiltration basin is 674.55. The lowest floor elevation of the proposed building is 676.50. Volume Abstraction Volume abstraction is provided by the infiltration basin. See Table 3 for abstraction requirements and provided volume. Table 3: Volume Abstraction Catchment Area Impervious Area Required Volume Volume [SF] Abstraction (1.1") Abstraction [CF] Provided [CF] Infiltration Basin 5740 526 843 A conservative infiltration rate of 0.3 in/hr was assumed for the soils in the infiltration area. With the outlet set 1.0 feet above the bottom of the basin, the system will draw down within 40 hours. Conclusion The proposed stormwater management system meets the requirements of the City of Oak Park Heights and Middle St. Croix WMO. Attachments A. Proposed Drainage Map B. Existing HydroCAD C. Proposed HydroCAD Attachment A - Proposed Drainage Map , E s 9`\ , / I I .., rG.� to m`"-d3...4' w \ N,.__ ' ".......... \ \ \ \ g cs „ v �� �� \-►� , \ \ =7....\„•,.\\\\\ N.,,_Th ./ \\__/--- ----- . ',V\\\\\\\ \ \ \ - , ,5' ? ::, '`.2-, l'I'l!'\\ \ \ \ s\ I , ______----1,0* 1A1111 \ t. \\\\ \A•\\`‘ \\ '''' 't 00 ° 4 :;� V Bit ,OKllig/ ►._ ,\ ��\`A\\V�AV A 1 1 \ 6 I r .% 0 cf, i:: ,,..\..,.\.,,, .\V\\\N,\,\\,\)\,IW,i I v ili (1 �� 4 �, lila • 1L n 6� ( ' _ 67 678 j / / ' , ' ��( / , rev6 / - 1 6>,9"ia "-" i \, \ , 1\,, \\\\\\N\ N X li 0' 40' 80' SHEET NUMBER: OAK PARK Westwood PROPOSED HEIGHTS JACC Phone (320)253-9495 1900 Medical Arts Ave S,Suite 100 DRAINAGE AREA CAPITAL Fax (320)358-2001 Sartell,MN 56377 Tot Free (800)270-9495 westwoodps.Com M A P HOLDINGS wed Professional Inc ' ' DATE: 10/14/24 Attachment B — Existing HydroCAD 1 EX) EX1 Subcat Reach Pon Link Routing Diagram for 2024-10-08 JACC-Oak Park Heights Prepared by Westwood Professional—Services. Printed 10/14/2024 HydroCAD®10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC 2024-10-08 "'_JACC- Oak Park Heights Type II 24-hr 2-year MSCWMO Rainfall=2.80 Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 2 Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1EX: EX1 Runoff Area=15,000 sf 32.27% Impervious Runoff Depth=1.16" Flow Length=150' Slope=0.0270'/' Tc=12.8 min CN=81 Runoff=0.56 cfs 0.033 af Total Runoff Area = 0.344 ac Runoff Volume= 0.033 af Average Runoff Depth = 1.16" 67.73%Pervious = 0.233 ac 32.27% Impervious = 0.111 ac 2024-10-08_JACC- Oak Park Heights Type ll 24-hr 2-year MSCWMO Rainfall=2.80" Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment 1 EX: EX1 Runoff = 0.56 cfs @ 12.05 hrs, Volume= 0.033 af, Depth= 1.16" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Type II 24-hr 2-year MSCWMO Rainfall=2.80" Area (sf) CN Description 4,840 98 Paved parking, HSG A 3,612 79 <50% Grass cover, Poor, HSG B 6,548 69 50-75% Grass cover, Fair, HSG B 15,000 81 Weighted Average 10,160 67.73% Pervious Area 4,840 32.27% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.8 150 0.0270 0.19 Sheet Flow, Grass: Short n= 0.150 P2= 2.80" 2024-10-08_JACC- Oak Park Heights Type II 24-hr 10-year MSCWMO Rainfall=4.20" Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 4 Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1EX: EX1 Runoff Area=15,000 sf 32.27% Impervious Runoff Depth=2.29" Flow Length=150' Slope=0.0270'/' Tc=12.8 min CN=81 Runoff=1.10 cfs 0.066 af Total Runoff Area = 0.344 ac Runoff Volume= 0.066 af Average Runoff Depth = 2.29" 67.73% Pervious = 0.233 ac 32.27%Impervious= 0.111 ac 2024-10-08_JACC- Oak Park Heights Type II 24-hr 10-year MSCWMO Rainfall=4.20" Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment 1 EX: EX1 Runoff = 1.10 cfs @ 12.05 hrs, Volume= 0.066 af, Depth= 2.29" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Type II 24-hr 10-year MSCWMO Rainfall=4.20" Area (sf) CN Description 4,840 98 Paved parking, HSG A 3,612 79 <50% Grass cover, Poor, HSG B 6,548 69 50-75% Grass cover, Fair, HSG B 15,000 81 Weighted Average 10,160 67.73% Pervious Area 4,840 32.27% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.8 150 0.0270 0.19 Sheet Flow, Grass: Short n= 0.150 P2= 2.80" 2024-10-08_JACC- Oak Park Heights Type ll 24-hr 100-year MSCWMO Rainfall=7.30" Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 6 Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1 EX: EX1 Runoff Area=15,000 sf 32.27% Impervious Runoff Depth=5.08" Flow Length=150' Slope=0.0270'/' Tc=12.8 min CN=81 Runoff=2.39 cfs 0.146 af Total Runoff Area = 0.344 ac Runoff Volume = 0.146 af Average Runoff Depth = 5.08" 67.73% Pervious = 0.233 ac 32.27%Impervious =0.111 ac 2024-10-08_JACC- Oak Park Heights Type II 24-hr 100-year MSCWMO Rainfall=7.30" Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 7 Summary for Subcatchment 1 EX: EX1 Runoff = 2.39 cfs @ 12.04 hrs, Volume= 0.146 af, Depth= 5.08" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Type II 24-hr 100-year MSCWMO Rainfall=7.30" Area (sf) CN Description 4,840 98 Paved parking, HSG A 3,612 79 <50% Grass cover, Poor, HSG B 6,548 69 50-75% Grass cover, Fair, HSG B 15,000 81 Weighted Average 10,160 67.73% Pervious Area 4,840 32.27% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.8 150 0.0270 0.19 Sheet Flow, Grass: Short n= 0.150 P2= 2.80" Attachment C — Proposed HydroCAD / \. \ . \ / > .,. PR1 Infiltration basin Subca) Reach on. Link Routing Diagram for 2024-10-08 JACC-Oak Park Heights Prepared by Westwood Professional Services, Printed 10/14/2024 \ '----\---' HydroCAD®10 20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC 2024-10-08_JACC- Oak Park Heights Type II 24-hr 2-year MSCWMO Rainfall=2.80" Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 2 Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: PR1 Runoff Area=15,000 sf 38.27% Impervious Runoff Depth=0.83" Tc=10.0 min CN=75 Runoff=0.43 cfs 0.024 af Pond 2P: Infiltration basin Peak Elev=674.39' Storage=710 cf Inflow=0.43 cfs 0.024 af Discarded=0.01 cfs 0.024 af Primary=0.00 cfs 0.000 af Outflow=0.01 cfs 0.024 af Total Runoff Area =0.344 ac Runoff Volume= 0.024 af Average Runoff Depth =0.83" 61.73%Pervious =0.213 ac 38.27% Impervious = 0.132 ac 2024-10-08_JACC- Oak Park Heights Type II 24-hr 2-year MSCWMO Rainfall=2.80" Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c sin 02351 ©2023 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment 1 S: PR1 Runoff = 0.43 cfs @ 12.03 hrs. Volume= 0.024 af, Depth= 0.83" Routed to Pond 2P : Infiltration basin Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Type II 24-hr 2-year MSCWMO Rainfall=2.80" Area (sf) CN Description 2,062 98 Paved parking, HSG B 3,678 98 Roofs, HSG B 3,362 61 >75% Grass cover, Good, HSG B 5,898 61 >75% Grass cover, Good, HSG B 15,000 75 Weighted Average 9,260 61.73% Pervious Area 5,740 38.27% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Direct Summary for Pond 2P: Infiltration basin Inflow Area = 0.344 ac, 38.27% Impervious, Inflow Depth = 0.83" for 2-year MSCWMO event Inflow = 0.43 cfs @ 12.03 hrs, Volume= 0.024 of Outflow = 0.01 cfs @ 20.05 hrs, Volume= 0.024 af, Atten= 98%, Lag=481.6 min Discarded = 0.01 cfs @ 20.05 hrs, Volume= 0.024 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Peak Elev= 674.39' @ 20.05 hrs Surf.Area= 1,129 sf Storage= 710 cf Plug-Flow detention time= 1,058.0 min calculated for 0.024 af (100% of inflow) Center-of-Mass det. time= 1,057.9 min ( 1,925.7 - 867.8 ) Volume Invert Avail.Storage Storage Description #1 673.50' 2,041 cf Custom Stage Data(Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 673.50 366 0 0 674.00 904 318 318 674.50 1,196 525 843 675.50 1,200 1,198 2,041 Device Routing Invert Outlet Devices #1 Primary 674.50' 45.0 deg x 60.0' long x 1.00' rise Sharp-Crested Vee/Trap Weir Cv= 2.56 (C= 3.20) #2 Discarded 673.50' 0.300 in/hr Exfiltration over Surface area 2024-10-08_JACC- Oak Park Heights Type II 24-hr 2-year MSCWMO Rainfall=2.80" Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 4 Discarded OutFlow Max=0.01 cfs© 20.05 hrs HW=674.39' (Free Discharge) L2=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.00 cfs © 0.00 hrs HW=673.50' (Free Discharge) t 1=Sharp-Crested Vee/Trap Weir ( Controls 0.00 cfs) 2024-10-08_JACC- Oak Park Heights Type II 24-hr 10-year MSCWMO Rainfall=4.20" Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 5 Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: PR1 Runoff Area=15,000 sf 38.27% Impervious Runoff Depth=1.82" Tc=10.0 min CN=75 Runoff=0.96 cfs 0.052 af Pond 2P: Infiltration basin Peak Elev=674.52' Storage=865 cf Inflow=0.96 cfs 0.052 af Discarded=0 01 cfs 0.028 af Primary=0.51 cfs 0.024 af Outflow=0.52 cfs 0.052 af Total Runoff Area = 0.344 ac Runoff Volume= 0.052 af Average Runoff Depth = 1.82" 61.73% Pervious = 0.213 ac 38.27%Impervious = 0.132 ac 2024-10-08_JACC- Oak Park Heights Type II 24-hr 10-year MSCWMO Rainfall=4.20" Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 6 Summary for Subcatchment 1 S: PR1 Runoff = 0.96 cfs @ 12.02 hrs, Volume= 0.052 af, Depth= 1.82" Routed to Pond 2P : Infiltration basin Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Type II 24-hr 10-year MSCWMO Rainfall=4.20" Area (sf) CN Description 2,062 98 Paved parking, HSG B 3,678 98 Roofs, HSG B 3,362 61 >75% Grass cover, Good. HSG B 5,898 61 >75% Grass cover, Good, HSG B 15,000 75 Weighted Average 9,260 61.73% Pervious Area 5,740 38.27% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Direct Summary for Pond 2P: Infiltration basin Inflow Area = 0.344 ac, 38.27% Impervious, Inflow Depth = 1.82" for 10-year MSCWMO event Inflow = 0.96 cfs @ 12.02 hrs, Volume= 0.052 of Outflow = 0.52 cfs @ 12.13 hrs, Volume= 0.052 af, Atten= 46%, Lag= 6.6 min Discarded = 0.01 cfs @ 12.13 hrs, Volume= 0.028 of Primary = 0.51 cfs @ 12.13 hrs, Volume= 0.024 of Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Peak Elev= 674.52' @ 12.13 hrs Surf.Area= 1,196 sf Storage= 865 cf Plug-Flow detention time= 645.6 min calculated for 0.052 of (100% of inflow) Center-of-Mass det. time= 645.8 min ( 1,489.8 - 844.0 ) Volume Invert Avail.Storage Storage Description #1 673.50' 2,041 cf Custom Stage Data(Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 673.50 366 0 0 674.00 904 318 318 674.50 1,196 525 843 675.50 1,200 1.198 2,041 Device Routing Invert Outlet Devices #1 Primary 674.50' 45.0 deg x 60.0' long x 1.00' rise Sharp-Crested Vee/Trap Weir Cv= 2.56 (C= 3.20) #2 Discarded 673.50' 0.300 in/hr Exfiltration over Surface area 2024-10-08_JACC- Oak Park Heights Type ll 24-hr 10-year MSCWMO Rainfall=4.20" Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 7 Discarded OutFlow Max=0.01 cfs @ 12.13 hrs HW=674.52' (Free Discharge) L2=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.50 cfs @ 12.13 hrs HW=674.52' (Free Discharge) L1=Sharp-Crested Vee/Trap Weir (Weir Controls 0.50 cfs © 0.44 fps) 2024-10-08_JACC- Oak Park Heights Type II 24-hr 100-year MSCWMO Rainfall=7.30" Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 8 Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: PR1 Runoff Area=15,000 sf 38.27% Impervious Runoff Depth=4.41" Tc=10.0 min CN=75 Runoff=2.32 cfs 0.127 of Pond 2P: Infiltration basin Peak Elev=674.55' Storage=905 cf Inflow=2.32 cfs 0.127 af Discarded=0.01 cfs 0.029 af Primary=2.31 cfs 0.097 af Outflow=2.32 cfs 0.127 af Total Runoff Area = 0.344 ac Runoff Volume= 0.127 af Average Runoff Depth =4.41" 61.73%Pervious = 0.213 ac 38.27%Impervious = 0.132 ac 2024-10-08_JACC- Oak Park Heights Type Il 24-hr 100-year MSCWMO Rainfall=7.30" Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 9 Summary for Subcatchment 1 S: PR1 Runoff = 2.32 cfs © 12.01 hrs, Volume= 0.127 af, Depth= 4.41" Routed to Pond 2P : Infiltration basin Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Type II 24-hr 100-year MSCWMO Rainfall=7.30" Area (sf) CN Description 2,062 98 Paved parking, HSG B 3,678 98 Roofs, HSG B 3,362 61 >75% Grass cover, Good, HSG B 5,898 61 >75% Grass cover, Good, HSG B 15,000 75 Weighted Average 9,260 61.73% Pervious Area 5,740 38.27% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Direct Summary for Pond 2P: Infiltration basin Inflow Area = 0.344 ac, 38.27% Impervious, Inflow Depth = 4.41" for 100-year MSCWMO event Inflow = 2.32 cfs © 12.01 hrs, Volume= 0.127 af Outflow = 2.32 cfs © 12.02 hrs, Volume= 0.127 af, Atten= 0%, Lag= 0.4 min Discarded = 0.01 cfs © 12.02 hrs, Volume= 0.029 af Primary = 2.31 cfs © 12.02 hrs, Volume= 0.097 af Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Peak Elev= 674.55' @ 12.02 hrs Surf.Area= 1,196 sf Storage= 905 cf Plug-Flow detention time= 272.9 min calculated for 0.127 af (100% of inflow) Center-of-Mass det. time= 273.2 min ( 1,091.8 - 818.6 ) Volume Invert Avail.Storage Storage Description #1 673.50' 2,041 cf Custom Stage Data(Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 673.50 366 0 0 674.00 904 318 318 674.50 1,196 525 843 675.50 1,200 1,198 2,041 Device Routing Invert Outlet Devices #1 Primary 674.50' 45.0 deg x 60.0' long x 1.00' rise Sharp-Crested Vee/Trap Weir Cv= 2.56 (C= 3.20) #2 Discarded 673.50' 0.300 in/hr Exfiltration over Surface area 2024-10-08_JACC- Oak Park Heights Type II 24-hr 100-year MSCWMO Rainfall=7.30 Prepared by Westwood Professional Services Printed 10/14/2024 HydroCAD® 10.20-5c s/n 02351 ©2023 HydroCAD Software Solutions LLC Page 10 Discarded OutFlow Max=0.01 cfs @ 12.02 hrs HW=674.55' (Free Discharge) L2=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=2.28 cfs @ 12.02 hrs HW=674.55' (Free Discharge) L1=Sharp-Crested Vee/Trap Weir (Weir Controls 2.28 cfs @ 0.73 fps)