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HomeMy WebLinkAbout20220612 YMCA Site Plan Mod SWPPP STORM WATER POLLUTION PREVENTION PLAN PLAN CHANGES, AUTHORIZATION, AND CHANGE CERTIFICATION CHANGES REQUIRED TO THE POLLUTION PREVENTION PLAN: An increase of 59 parkinq spaces has been proposed to service the addition to the north face of the YMCA buildinq. Porous pavement has been proposed to treat and dispose of stormwater in these expanded parking areas. Additionally, the footprint of the building addition has increased in size by 5,587 sf. To account for this increase in impervious area the infiltration chamber field previously designed for the former building footprint has also increased in size. REASONS FOR CHANGES: In total, 11,129 sf of new impervious area will be created as a result of these chanqes resultinq in a required WQv of 1,013 cf. This WQv will be treated via porous pavement used in the additional parking spaces and an additional (20) SC-310 infiltration chambers to the chamber field. REQUESTED BY: The LA Group DATE: 6/15/2022 AUTHORIZED BY: DATE: CERTIFICATION OF CHANGES: I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gathered and evaluated the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that false statements made herein are punishable as a Class A misdemeanor pursuant to Section 210.45 of the penal code. 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O—p— �S � ��SF � YMCA Site Amendment W1 - Previousl A roved Pro osed Condition y pp p 290 West Avenue, Saratoga Springs, NY 12866 Date: 6/15/2022 � 0 10 25 50 100 � The LA GROUP SCALE: 1 =rJ� LandscapeArchitecture&EngineeringPC AP-1 A�1 cB E2.2 E3 H#1 Subcat E2.2 Subcat E3 Manlhole � cB AP-2 E2 SMP1 P1 AP-2 Subcat E2 Un rground Chambers Undergrounp Chambers � SMP2 � E2.1 E1.1 EXCHAM Permeable PavementSubcat E2.1 Subcat E1.1 Un rground Chambers E1 Subcat E1 Subcat Reach on Link Routing Diagram for 201477_Post Development_Rev Prepared by The LA Group, Printed 6/15/2022 HydroCADO 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC 201477 Post Development_Rev Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 2 Area Listing (selected nodes) Area CN Description (sq-ft) (s u bcatch me nt-n u m be rs) 75,340 39 >75% Grass cover, Good, HSG A (E1.1, E2, E2.1, E2.2, E3) 85,609 98 Paved parking, HSG A (E1, E1.1, E2, E2.1, E2.2, E3) 54,059 30 Woods, Good, HSG A (E2, E2.2, E3) 215,009 60 TOTAL AREA 201477 Post Development_Rev Type 1124-hr 10yr Rainfa11=3.75" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 3 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS, Weighted-Q Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentE1: Subcat E1 RunoffArea=49,855 sf 100.00% Impervious Runoff Depth=3.52" Tc=6.0 min CN=98 Runoff=5.92 cfs 14,606 cf SubcatchmentE1.1: Subcat E1.1 RunoffArea=16,365 sf 100.00% Impervious Runoff Depth=3.52" Tc=6.0 min CN=WQ Runoff=1.94 cfs 4,795 cf SubcatchmentE2: Subcat E2 Runoff Area=32,822 sf 29.36% Impervious Runoff Depth=1.04" Tc=6.0 min CN=WQ Runoff=1.14 cfs 2,857 cf Subcatchment E2.1: Subcat E2.1 Runoff Area=5,678 sf 54.80% Impervious Runoff Depth=1.94" Tc=6.0 min CN=WQ Runoff=0.37 cfs 917 cf SubcatchmentE2.2: Subcat E2.2 Runoff Area=18,195 sf 8.20% Impervious Runoff Depth=0.30" Tc=6.0 min CN=WQ Runoff=0.18 cfs 458 cf SubcatchmentE3: Subcat E3 Runoff Area=92,093 sf 5.59% Impervious Runoff Depth=0.21" Flow Length=125' Tc=27.3 min CN=WQ Runoff=0.35 cfs 1,599 cf Pond EXCHAM: Underground Chambers Peak EIev=308.17' Storage=3,721 cf Inflow=5.92 cfs 14,606 cf Discarded=0.50 cfs 10,678 cf Primary=1.70 cfs 3,929 cf Outflow=2.20 cfs 14,606 cf Pond MH#1: Manhole Peak EIev=306.81' Inflow=1.74 cfs 4,014 cf 12.0" Round Culvert n=0.013 L=69.0' S=0.0100 '/' Outflow=1.74 cfs 4,014 cf Pond P1: Underground Chambers Peak EIev=309.08' Inflow=1.70 cfs 3,929 cf 8.0" Round Culvert n=0.013 L=107.0' S=0.0100 '/' Outflow=1.70 cfs 3,929 cf Pond SMP1: Underground Chambers Peak EIev=307.86' Storage=1,213 cf Inflow=1.94 cfs 4,795 cf Discarded=0.38 cfs 4,709 cf Primary=0.04 cfs 85 cf Outflow=0.42 cfs 4,795 cf Pond SMP2: Permeable Pavement Peak EIev=308.39' Storage=917 cf Inflow=0.37 cfs 917 cf Outflow=0.00 cfs 0 cf Link AP-1: AP-1 Inflow=2.04 cfs 5,612 cf Primary=2.04 cfs 5,612 cf Link AP-2: AP-2 Inflow=1.32 cfs 3,315 cf Primary=1.32 cfs 3,315 cf Total Runoff Area = 215,009 sf Runoff Volume = 25,231 cf Average Runoff Depth = 1.41" 60.18% Pervious = 129,399 sf 39.82% Impervious = 85,609 sf 201477 Post Development_Rev Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 1 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS, Weighted-Q Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentE1: Subcat E1 RunoffArea=49,855 sf 100.00% Impervious Runoff Depth=5.96" Tc=6.0 min CN=98 Runoff=9.84 cfs 24,768 cf SubcatchmentE1.1: Subcat E1.1 RunoffArea=16,365 sf 100.00% Impervious Runoff Depth=5.96" Tc=6.0 min CN=WQ Runoff=3.23 cfs 8,130 cf SubcatchmentE2: Subcat E2 Runoff Area=32,822 sf 29.36% Impervious Runoff Depth=2.03" Tc=6.0 min CN=WQ Runoff=2.00 cfs 5,540 cf Subcatchment E2.1: Subcat E2.1 Runoff Area=5,678 sf 54.80% Impervious Runoff Depth=3.49" Tc=6.0 min CN=WQ Runoff=0.63 cfs 1,654 cf SubcatchmentE2.2: Subcat E2.2 Runoff Area=18,195 sf 8.20% Impervious Runoff Depth=0.81" Tc=6.0 min CN=WQ Runoff=0.38 cfs 1,232 cf SubcatchmentE3: Subcat E3 Runoff Area=92,093 sf 5.59% Impervious Runoff Depth=0.63" Flow Length=125' Tc=27.3 min CN=WQ Runoff=0.73 cfs 4,798 cf Pond EXCHAM: Underground Chambers Peak Elev=319.18' Storage=6,291 cf Inflow=9.84 cfs 24,768 cf Discarded=0.50 cfs 15,692 cf Primary=5.83 cfs 9,076 cf Outflow=6.33 cfs 24,768 cf Pond MH#1: Manhole Peak EIev=309.62' Inflow=5.91 cfs 9,563 cf 12.0" Round Culvert n=0.013 L=69.0' S=0.0100 '/' Outflow=5.91 cfs 9,563 cf Pond P1: Underground Chambers Peak Elev=337.89' Inflow=5.83 cfs 9,076 cf 8.0" Round Culvert n=0.013 L=107.0' S=0.0100 '/' Outflow=5.83 cfs 9,076 cf Pond SMP1: Underground Chambers Peak EIev=308.85' Storage=2,446 cf Inflow=3.23 cfs 8,130 cf Discarded=0.38 cfs 7,644 cf Primary=0.22 cfs 487 cf Outflow=0.59 cfs 8,130 cf Pond SMP2: Permeable Pavement Peak EIev=308.70' Storage=1,654 cf Inflow=0.63 cfs 1,654 cf Outflow=0.00 cfs 0 cf LinkAP-1: AP-1 Inflow=6.36 cfs 14,361 cf Primary=6.36 cfs 14,361 cf Link AP-2: AP-2 Inflow=2.36 cfs 6,772 cf Primary=2.36 cfs 6,772 cf Total Runoff Area = 215,009 sf Runoff Volume = 46,123 cf Average Runoff Depth = 2.57" 60.18% Pervious = 129,399 sf 39.82% Impervious = 85,609 sf 201477 Post Development_Rev Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 2 Summary for Subcatchment E1: Subcat E1 Runoff = 9.84 cfs @ 11.96 hrs, Volume= 24,768 cf, Depth= 5.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr Rainfa11=6.20" Area (s� CN Description 49,855 98 Paved parking, HSG A 49,855 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment E1.1: Subcat E1.1 Runoff = 3.23 cfs @ 11.96 hrs, Volume= 8,130 cf, Depth= 5.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr Rainfa11=6.20" Area (s� CN Description 0 39 >75% Grass cover, Good, HSG A 16,365 98 Paved parking, HSG A 16,365 Weighted Average 0 0.00% Pervious Area 16,365 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment E2: Subcat E2 Runoff = 2.00 cfs @ 11.97 hrs, Volume= 5,540 cf, Depth= 2.03" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr Rainfa11=6.20" Area (s� CN Description 16,666 39 >75% Grass cover, Good, HSG A 9,638 98 Paved parking, HSG A 6,518 30 Woods, Good, HSG A 32,822 Weighted Average 23,184 70.64% Pervious Area 9,638 29.36% Impervious Area 201477 Post Development_Rev Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 3 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment E2.1: Subcat E2.1 Runoff = 0.63 cfs @ 11.97 hrs, Volume= 1,654 cf, Depth= 3.49" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr Rainfa11=6.20" Area (s� CN Description 2,566 39 >75% Grass cover, Good, HSG A 3,111 98 Paved parking, HSG A 5,678 Weighted Average 2,566 45.20% Pervious Area 3,111 54.80% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment E2.2: Subcat E2.2 Runoff = 0.38 cfs @ 11.99 hrs, Volume= 1,232 cf, Depth= 0.81" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr Rainfa11=6.20" Area (s� CN Description 10,537 39 >75% Grass cover, Good, HSG A 1,492 98 Paved parking, HSG A 6,167 30 Woods, Good, HSG A 18,195 Weighted Average 16,704 91.80% Pervious Area 1,492 8.20% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment E3: Subcat E3 Runoff = 0.73 cfs @ 12.23 hrs, Volume= 4,798 cf, Depth= 0.63" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr Rainfa11=6.20" 201477 Post Development_Rev Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 4 Area (s� CN Description 45,571 39 >75% Grass cover, Good, HSG A 5,148 98 Paved parking, HSG A 41,374 30 Woods, Good, HSG A 92,093 Weighted Average 86,945 94.41% Pervious Area 5,148 5.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 26.7 100 0.0150 0.06 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.60" 0.6 25 0.0200 0.71 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 27.3 125 Total Summary for Pond EXCHAM: Underground Chambers InflowArea = 49,855 sf,100.00% Impervious, Inflow Depth = 5.96" for 100yr event Inflow = 9.84 cfs @ 11.96 hrs, Volume= 24,768 cf Outflow = 6.33 cfs @ 12.05 hrs, Volume= 24,768 cf, Atten= 36%, Lag= 5.3 min Discarded = 0.50 cfs @ 11.15 hrs, Volume= 15,692 cf Primary = 5.83 cfs @ 12.05 hrs, Volume= 9,076 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 319.18' @ 12.05 hrs Surf.Area= 2,909 sf Storage= 6,291 cf Plug-Flow detention time= 16.6 min calculated for 24,742 cf(100% of inflow) Center-of-Mass det. time= 16.6 min ( 757.1 - 740.5 ) Volume Invert Avail.Storage Storage Description #1A 306.32' 2,593 cf 39.50'W x 73.64'L x 3.50'H Field A 10,181 cf Overall - 3,698 cf Embedded = 6,483 cf x 40.0% Voids #2A 306.82' 3,698 cf ADS StormTech SC-740 x 80 Inside#1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 8 rows 6,291 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 306.32' 7.500 in/hr Exfiltration over SurFace area #2 Primary 306.82' 8.0" Vert. Orifice/Grate C= 0.600 Discarded OutFlow Max=0.50 cfs @ 11.15 hrs HW=306.39' (Free Discharge) L1=Exfiltration (Exfiltration Controls 0.50 cfs) Primary OutFlow Max=5.80 cfs @ 12.05 hrs HW=319.05' (Free Discharge) L2=0rifice/Grate (Orifice Controls 5.80 cfs @ 16.61 fps) 201477 Post Development_Rev Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 5 Summary for Pond MH#1: Manhole InflowArea = 66,220 sf,100.00% Impervious, Inflow Depth = 1.73" for 100yr event Inflow = 5.91 cfs @ 12.05 hrs, Volume= 9,563 cf Outflow = 5.91 cfs @ 12.05 hrs, Volume= 9,563 cf, Atten= 0%, Lag= 0.0 min Primary = 5.91 cfs @ 12.05 hrs, Volume= 9,563 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 309.62' @ 12.05 hrs Device Routing Invert Outlet Devices #1 Primary 306.09' 12.0" Round Culvert L= 69.0' Ke= 0.500 Inlet/ Outlet Invert= 306.09' / 305.40' S= 0.0100 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=5.87 cfs @ 12.05 hrs HW=309.58' (Free Discharge) L1=Culvert (Barrel Controls 5.87 cfs @ 7.48 fps) Summary for Pond P1: Underground Chambers InflowArea = 49,855 sf,100.00% Impervious, Inflow Depth = 2.18" for 100yr event Inflow = 5.83 cfs @ 12.05 hrs, Volume= 9,076 cf Outflow = 5.83 cfs @ 12.05 hrs, Volume= 9,076 cf, Atten= 0%, Lag= 0.0 min Primary = 5.83 cfs @ 12.05 hrs, Volume= 9,076 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs/2 Peak Elev= 337.89' @ 12.05 hrs Device Routing Invert Outlet Devices #1 Primary 306.82' 8.0" Round Culvert L= 107.0' Ke= 0.500 Inlet/ Outlet Invert= 306.82' / 305.75' S= 0.0100 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf Primary OutFlow Max=5.80 cfs @ 12.05 hrs HW=337.54' (Free Discharge) L1=Culvert (Barrel Controls 5.80 cfs @ 16.61 fps) Summary for Pond SMP1: Underground Chambers InflowArea = 16,365 sf,100.00% Impervious, Inflow Depth = 5.96" for 100yr event Inflow = 3.23 cfs @ 11.96 hrs, Volume= 8,130 cf Outflow = 0.59 cfs @ 12.16 hrs, Volume= 8,130 cf, Atten= 82%, Lag= 12.0 min Discarded = 0.38 cfs @ 11.65 hrs, Volume= 7,644 cf Primary = 0.22 cfs @ 12.16 hrs, Volume= 487 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 308.85' @ 12.17 hrs Surf.Area= 2,182 sf Storage= 2,446 cf Plug-Flow detention time= 29.7 min calculated for 8,122 cf(100% of inflow) Center-of-Mass det. time= 29.7 min ( 770.2 - 740.5 ) 201477 Post Development_Rev Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 6 Volume Invert Avail.Storage Storage Description #1A 306.90' 1,539 cf 24.83'W x 87.88'L x 2.33'H Field A 5,092 cf Overall - 1,245 cf Embedded = 3,847 cf x 40.0% Voids #2A 307.40' 1,245 cf ADS StormTech SC-310 x 84 Inside#1 Effective Size= 28.9"W x 16.0"H => 2.07 sf x 7.12'L = 14.7 cf Overall Size= 34.0"W x 16.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 2.07 sf x 7 rows 2,784 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 306.90' 7.500 in/hr Exfiltration over SurFace area #2 Device 4 307.50' 1.7" Vert. Orifice/Grate C= 0.600 #3 Device 4 308.80' 4.0' long Sharp-Crested Vee/Trap Weir Cv= 2.62 (C= 3.28) #4 Primary 307.30' 12.0" Round Culvert L= 47.0' Ke= 0.500 Inlet/ Outlet Invert= 307.30' / 306.10' S= 0.0255 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Discarded OutFlow Max=0.38 cfs @ 11.65 hrs HW=306.95' (Free Discharge) L1=Exfiltration (Exfiltration Controls 0.38 cfs) Primary OutFlow Max=0.20 cfs @ 12.16 hrs HW=308.84' (Free Discharge) L4=Culvert (Passes 0.20 cfs of 3.86 cfs potential flow) �2=0rifice/Grate (Orifice Controls 0.09 cfs @ 5.43 fps) 3=Sharp-Crested Vee/Trap Weir(Weir Controls 0.11 cfs @ 0.67 fps) Summary for Pond SMP2: Permeable Pavement Inflow Area = 5,678 sf, 54.80% Impervious, Inflow Depth = 3.49" for 100yr event Inflow = 0.63 cfs @ 11.97 hrs, Volume= 1,654 cf Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0 cf, Atten= 100%, Lag= 0.0 min Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 308.70' @ 24.40 hrs Surf.Area= 5,904 sf Storage= 1,654 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 #1 308.00' 2,362 cf 18.00'W x 328.00'L x 1.00'H Prismatoid 5,904 cf Overall x 40.0% Voids Summary for Link AP-1: AP-1 Inflow Area = 158,314 sf, 45.08% Impervious, Inflow Depth = 1.09" for 100yr event Inflow = 6.36 cfs @ 12.05 hrs, Volume= 14,361 cf Primary = 6.36 cfs @ 12.05 hrs, Volume= 14,361 cf, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs 201477 Post Development_Rev Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 7 Summary for Link AP-2: AP-2 InflowArea = 51,017 sf, 21.82% Impervious, Inflow Depth = 1.59" for 100yr event Inflow = 2.36 cfs @ 11.97 hrs, Volume= 6,772 cf Primary = 2.36 cfs @ 11.97 hrs, Volume= 6,772 cf, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Proposed Condition Watershed Map HydroCAD Calculations % / I � `� � a � Uaa � ' �� � J� � � ¢N � / � I � Q J� O °� I �I � � /// �� O m� � I � I � � � m�'a° ��� � � �/ � � � � a �N ;� � I C I : �� `� �j // I � I _ �6� / � /� O � �, i / a � b o � N / O � �� / � / / ��� .��••~' � / ��� a �I / �� �•• . 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''� � � � ' • -y'S , , SAN \� � _ Bikepath � � � � � � � � � � � � � � �'� � � � � � � � � � i . . . . . � i � - - - - . - - - - � � � — — — � � � � — — _ — —��— — —SAN� �A�� — — . — — . — _ \� F `rr \ -- — � �0� _ _ — �.0 BL Bik s �� � .� - - - - _ � S.I�.L,# 1/8.00-4-23 saro�°.o \ � �ands of The Cit of Sarato a ' s L.1734 - - Y g p.12 � -�—�_�—�- a a o—o—o �e —a—o—�=�o=o= �-� — �—a— — — — — — — — —°_°—�_��_� —o=o— — — _ — — — — — — —�—o_o_o_o_ L3 _ _ �—O_O_O—O—O—O_O=O—O—O—O—O—O—O—O�=0—[�—n— � O—0= — —Q=Q_Q_ Q—Q— Q— � �s�_ 0—�—�—�-0— O�Q—O—O— \ �S � ��SF � YMCA Site Amendment W2 - Pro osed Condition p 290 West Avenue, Saratoga Springs, NY 12866 Date: 6/15/2022 � 0 10 25 50 100 � The LA GROUP SCALE: 1��=5�� Landscape Architecture&Engineering P C AP-1 A�1 cB E2.2 E3 H#1 Subcat E2.2 Subcat E3 Manlhole � cB AP-2 E2 E1.1 � SMP1 P1 AP-2 Subcat E2 Subcat E1.tlln rground Chambers Undergrounp Chambers Rev. I SMP2 � E2.1 E1.3 EXCHAM Permeable PavementSubcat E2.1 Subcat E1.3 Un rground Chambers E1 Subcat E1 Subcat Reach on Link Routing Diagram for 2021039 Post Development Prepared by The LA Group, Printed 6/15/2022 HydroCADO 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC 2021039 Post Development Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 2 Area Listing (selected nodes) Area CN Description (sq-ft) (s u bcatch me nt-n u m be rs) 73,934 39 >75% Grass cover, Good, HSG A (E1, E1.3, E2, E2.1, E2.2, E3) 97,642 98 Paved parking, HSG A (E1, E1.1, E1.3, E2, E2.1, E2.2, E3) 44,474 30 Woods, Good, HSG A (E2, E2.2, E3) 216,049 64 TOTAL AREA 2021039 Post Development Type 1124-hr 10yr Rainfa11=3.75" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 3 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS, Weighted-Q Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentE1: Subcat E1 RunoffArea=49,854 sf 100.00% Impervious Runoff Depth=3.52" Tc=6.0 min CN=WQ Runoff=5.92 cfs 14,606 cf SubcatchmentE1.1: Subcat E1.1 RunoffArea=16,569 sf 100.00% Impervious Runoff Depth=3.52" Tc=6.0 min CN=98 Runoff=1.97 cfs 4,854 cf SubcatchmentE1.3: Subcat E1.3 Runoff Area=5,382 sf 99.92% Impervious Runoff Depth=3.51" Tc=6.0 min CN=WQ Runoff=0.64 cfs 1,576 cf Subcatchment E2: Subcat E2 Runoff Area=15,372 sf 19.41% Impervious Runoff Depth=0.70" Tc=6.0 min CN=WQ Runoff=0.35 cfs 897 cf SubcatchmentE2.1: Subcat E2.1 Runoff Area=23,140 sf 86.40% Impervious Runoff Depth=3.04" Tc=6.0 min CN=WQ Runoff=2.37 cfs 5,864 cf SubcatchmentE2.2: Subcat E2.2 Runoff Area=16,990 sf 2.63% Impervious Runoff Depth=0.11" Tc=6.0 min CN=WQ Runoff=0.05 cfs 159 cf SubcatchmentE3: Subcat E3 Runoff Area=88,741 sf 2.72% Impervious Runoff Depth=0.11" Flow Length=125' Tc=27.3 min CN=WQ Runoff=0.16 cfs 797 cf Pond EXCHAM: Underground Chambers Peak EIev=308.17' Storage=3,721 cf Inflow=5.92 cfs 14,606 cf Discarded=0.50 cfs 10,678 cf Primary=1.70 cfs 3,928 cf Outflow=2.20 cfs 14,606 cf Pond MH#1: Manhole Peak EIev=306.82' Inflow=1.74 cfs 4,043 cf 12.0" Round Culvert n=0.013 L=69.0' S=0.0100 '/' Outflow=1.74 cfs 4,043 cf Pond P1: Underground Chambers Peak EIev=309.08' Inflow=1.70 cfs 3,928 cf 8.0" Round Culvert n=0.013 L=107.0' S=0.0100 '/' Outflow=1.70 cfs 3,928 cf Pond SMP1: Underground Chambers Rev. Peak EIev=307.94' Storage=1,680 cf Inflow=2.61 cfs 6,430 cf Discarded=0.48 cfs 6,315 cf Primary=0.05 cfs 115 cf Outflow=0.52 cfs 6,430 cf Pond SMP2: Permeable Pavement Peak EIev=308.01' Storage=34 cf Inflow=2.37 cfs 5,864 cf Outflow=2.36 cfs 5,864 cf Link AP-1: AP-1 Inflow=1.88 cfs 4,841 cf Primary=1.88 cfs 4,841 cf LinkAP-2: AP-2 Inflow=0.41 cfs 1,056 cf Primary=0.41 cfs 1,056 cf Total Runoff Area = 216,049 sf Runoff Volume = 28,754 cf Average Runoff Depth = 1.60" 54.81% Pervious = 118,407 sf 45.19% Impervious = 97,642 sf 2021039 Post Development Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 1 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS, Weighted-Q Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentE1: Subcat E1 RunoffArea=49,854 sf 100.00% Impervious Runoff Depth=5.96" Tc=6.0 min CN=WQ Runoff=9.84 cfs 24,767 cf SubcatchmentE1.1: Subcat E1.1 RunoffArea=16,569 sf 100.00% Impervious Runoff Depth=5.96" Tc=6.0 min CN=98 Runoff=3.27 cfs 8,232 cf Subcatchment E1.3: Subcat E1.3 Runoff Area=5,382 sf 99.92% Impervious Runoff Depth=5.96" Tc=6.0 min CN=WQ Runoff=1.06 cfs 2,672 cf Subcatchment E2: Subcat E2 Runoff Area=15,372 sf 19.41% Impervious Runoff Depth=1.54" Tc=6.0 min CN=WQ Runoff=0.68 cfs 1,977 cf SubcatchmentE2.1: Subcat E2.1 Runoff Area=23,140 sf 86.40% Impervious Runoff Depth=5.22" Tc=6.0 min CN=WQ Runoff=3.96 cfs 10,065 cf Subcatchment E2.2: Subcat E2.2 Runoff Area=16,990 sf 2.63% Impervious Runoff Depth=0.59" Tc=6.0 min CN=WQ Runoff=0.22 cfs 837 cf SubcatchmentE3: Subcat E3 Runoff Area=88,741 sf 2.72% Impervious Runoff Depth=0.46" Flow Length=125' Tc=27.3 min CN=WQ Runoff=0.43 cfs 3,416 cf Pond EXCHAM: Underground Chambers Peak Elev=319.17' Storage=6,291 cf Inflow=9.84 cfs 24,767 cf Discarded=0.50 cfs 15,692 cf Primary=5.83 cfs 9,075 cf Outflow=6.33 cfs 24,767 cf Pond MH#1: Manhole Peak EIev=309.71' Inflow=6.00 cfs 9,901 cf 12.0" Round Culvert n=0.013 L=69.0' S=0.0100 '/' Outflow=6.00 cfs 9,901 cf Pond P1: Underground Chambers Peak Elev=337.85' Inflow=5.83 cfs 9,075 cf 8.0" Round Culvert n=0.013 L=107.0' S=0.0100 '/' Outflow=5.83 cfs 9,075 cf Pond SMP1: Underground Chambers Rev. Peak EIev=308.97' Storage=3,202 cf Inflow=4.33 cfs 10,904 cf Discarded=0.48 cfs 10,078 cf Primary=0.98 cfs 826 cf Outflow=1.46 cfs 10,904 cf Pond SMP2: Permeable Pavement Peak EIev=308.05' Storage=230 cf Inflow=3.96 cfs 10,065 cf Outflow=3.20 cfs 10,065 cf LinkAP-1: AP-1 Inflow=6.24 cfs 13,317 cf Primary=6.24 cfs 13,317 cf Link AP-2: AP-2 Inflow=0.88 cfs 2,814 cf Primary=0.88 cfs 2,814 cf Total Runoff Area = 216,049 sf Runoff Volume = 51,966 cf Average Runoff Depth = 2.89" 54.81% Pervious = 118,407 sf 45.19% Impervious = 97,642 sf 2021039 Post Development Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 2 Summary for Subcatchment E1: Subcat E1 Runoff = 9.84 cfs @ 11.96 hrs, Volume= 24,767 cf, Depth= 5.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr Rainfa11=6.20" Area (s� CN Description 1 39 >75% Grass cover, Good, HSG A 49,853 98 Paved parking, HSG A 49,854 Weighted Average 1 0.00% Pervious Area 49,853 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment E1.1: Subcat E1.1 Runoff = 3.27 cfs @ 11.96 hrs, Volume= 8,232 cf, Depth= 5.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr Rainfa11=6.20" Area (s� CN Description 16,569 98 Paved parking, HSG A 16,569 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment E1.3: Subcat E1.3 Runoff = 1.06 cfs @ 11.96 hrs, Volume= 2,672 cf, Depth= 5.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr Rainfa11=6.20" Area (s� CN Description 4 39 >75% Grass cover, Good, HSG A 5,378 98 Paved parking, HSG A 5,382 Weighted Average 4 0.08% Pervious Area 5,378 99.92% Impervious Area 2021039 Post Development Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 3 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment E2: Subcat E2 Runoff = 0.68 cfs @ 11.98 hrs, Volume= 1,977 cf, Depth= 1.54" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr Rainfa11=6.20" Area (s� CN Description 11,642 39 >75% Grass cover, Good, HSG A 2,983 98 Paved parking, HSG A 747 30 Woods, Good, HSG A 15,372 Weighted Average 12,389 80.59% Pervious Area 2,983 19.41% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment E2.1: Subcat E2.1 Runoff = 3.96 cfs @ 11.96 hrs, Volume= 10,065 cf, Depth= 5.22" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr Rainfa11=6.20" Area (s� CN Description 3,147 39 >75% Grass cover, Good, HSG A 19,993 98 Paved parking, HSG A 23,140 Weighted Average 3,147 13.60% Pervious Area 19,993 86.40% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment E2.2: Subcat E2.2 Runoff = 0.22 cfs @ 12.01 hrs, Volume= 837 cf, Depth= 0.59" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr Rainfa11=6.20" 2021039 Post Development Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 4 Area (s� CN Description 14,190 39 >75% Grass cover, Good, HSG A 448 98 Paved parking, HSG A 2,352 30 Woods, Good, HSG A 16,990 Weighted Average 16,543 97.37% Pervious Area 448 2.63% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment E3: Subcat E3 Runoff = 0.43 cfs @ 12.26 hrs, Volume= 3,416 cf, Depth= 0.46" Runoff by SCS TR-20 method, UH=SCS, Weighted-Q, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100yr Rainfa11=6.20" Area (s� CN Description 44,949 39 >75% Grass cover, Good, HSG A 2,418 98 Paved parking, HSG A 41,374 30 Woods, Good, HSG A 88,741 Weighted Average 86,324 97.28% Pervious Area 2,418 2.72% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 26.7 100 0.0150 0.06 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.60" 0.6 25 0.0200 0.71 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 27.3 125 Total Summary for Pond EXCHAM: Underground Chambers InflowArea = 49,854 sf,100.00% Impervious, Inflow Depth = 5.96" for 100yr event Inflow = 9.84 cfs @ 11.96 hrs, Volume= 24,767 cf Outflow = 6.33 cfs @ 12.05 hrs, Volume= 24,767 cf, Atten= 36%, Lag= 5.3 min Discarded = 0.50 cfs @ 11.15 hrs, Volume= 15,692 cf Primary = 5.83 cfs @ 12.05 hrs, Volume= 9,075 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 319.17' @ 12.05 hrs Surf.Area= 2,909 sf Storage= 6,291 cf Plug-Flow detention time= 16.6 min calculated for 24,741 cf(100% of inflow) Center-of-Mass det. time= 16.6 min ( 757.1 - 740.5 ) 2021039 Post Development Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 5 Volume Invert Avail.Storage Storage Description #1A 306.32' 2,593 cf 39.50'W x 73.64'L x 3.50'H Field A 10,181 cf Overall - 3,698 cf Embedded = 6,483 cf x 40.0% Voids #2A 306.82' 3,698 cf ADS StormTech SC-740 x 80 Inside#1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 8 rows 6,291 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 306.32' 7.500 in/hr Exfiltration over SurFace area #2 Primary 306.82' 8.0" Vert. Orifice/Grate C= 0.600 Discarded OutFlow Max=0.50 cfs @ 11.15 hrs HW=306.39' (Free Discharge) L1=Exfiltration (Exfiltration Controls 0.50 cfs) Primary OutFlow Max=5.79 cfs @ 12.05 hrs HW=319.04' (Free Discharge) L2=0rifice/Grate (Orifice Controls 5.79 cfs @ 16.60 fps) Summary for Pond MH#1: Manhole InflowArea = 71,805 sf, 99.99% Impervious, Inflow Depth = 1.65" for 100yr event Inflow = 6.00 cfs @ 12.05 hrs, Volume= 9,901 cf Outflow = 6.00 cfs @ 12.05 hrs, Volume= 9,901 cf, Atten= 0%, Lag= 0.0 min Primary = 6.00 cfs @ 12.05 hrs, Volume= 9,901 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 309.71' @ 12.05 hrs Device Routing Invert Outlet Devices #1 Primary 306.09' 12.0" Round Culvert L= 69.0' Ke= 0.500 Inlet/ Outlet Invert= 306.09' / 305.40' S= 0.0100 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=5.80 cfs @ 12.05 hrs HW=309.51' (Free Discharge) L1=Culvert (Barrel Controls 5.80 cfs @ 7.39 fps) Summary for Pond P1: Underground Chambers InflowArea = 49,854 sf,100.00% Impervious, Inflow Depth = 2.18" for 100yr event Inflow = 5.83 cfs @ 12.05 hrs, Volume= 9,075 cf Outflow = 5.83 cfs @ 12.05 hrs, Volume= 9,075 cf, Atten= 0%, Lag= 0.0 min Primary = 5.83 cfs @ 12.05 hrs, Volume= 9,075 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs/2 Peak Elev= 337.85' @ 12.05 hrs Device Routing Invert Outlet Devices #1 Primary 306.82' 8.0" Round Culvert L= 107.0' Ke= 0.500 2021039 Post Development Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 6 Inlet/ Outlet Invert= 306.82' / 305.75' S= 0.0100 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf Primary OutFlow Max=5.79 cfs @ 12.05 hrs HW=337.51' (Free Discharge) L1=Culvert (Barrel Controls 5.79 cfs @ 16.60 fps) Summary for Pond SMP1: Underground Chambers Rev. InflowArea = 21,952 sf, 99.98% Impervious, Inflow Depth = 5.96" for 100yr event Inflow = 4.33 cfs @ 11.96 hrs, Volume= 10,904 cf Outflow = 1.46 cfs @ 12.11 hrs, Volume= 10,904 cf, Atten= 66%, Lag= 8.9 min Discarded = 0.48 cfs @ 11.65 hrs, Volume= 10,078 cf Primary = 0.98 cfs @ 12.11 hrs, Volume= 826 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 308.97' @ 12.11 hrs Surf.Area= 2,753 sf Storage= 3,202 cf Plug-Flow detention time= 29.9 min calculated for 10,892 cf(100% of inflow) Center-of-Mass det. time= 29.8 min ( 770.3 - 740.5 ) Volume Invert Avail.Storage Storage Description #1A 306.90' 1,539 cf 24.83'W x 87.88'L x 2.33'H Field A 5,092 cf Overall - 1,245 cf Embedded = 3,847 cf x 40.0% Voids #2A 307.40' 1,245 cf ADS StormTech SC-310 x 84 Inside#1 Effective Size= 28.9"W x 16.0"H => 2.07 sf x 7.12'L = 14.7 cf Overall Size= 34.0"W x 16.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 2.07 sf x 7 rows #3B 306.90' 414 cf 7.67'W x 74.40'L x 2.33'H Field B 1,331 cf Overall - 295 cf Embedded = 1,036 cf x 40.0% Voids #4B 307.40' 295 cf ADS StormTech SC-310 +Cap x 20 Inside#3 Effective Size= 28.9"W x 16.0"H => 2.07 sf x 7.12'L = 14.7 cf Overall Size= 34.0"W x 16.0"H x 7.56'L with 0.44' Overlap 20 Chambers in 2 Rows 3,493 cf Total Available Storage Storage Group A created with Chamber Wizard Storage Group B created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 306.90' 7.500 in/hr Exfiltration over SurFace area #2 Device 4 307.50' 1.7" Vert. Orifice/Grate C= 0.600 #3 Device 4 308.80' 4.0' long Sharp-Crested Vee/Trap Weir Cv= 2.62 (C= 3.28) #4 Primary 307.30' 12.0" Round Culvert L= 47.0' Ke= 0.500 Inlet/ Outlet Invert= 307.30' / 306.10' S= 0.0255 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf 2021039 Post Development Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 7 Discarded OutFlow Max=0.48 cfs @ 11.65 hrs HW=306.96' (Free Discharge) L1=Exfiltration (Exfiltration Controls 0.48 cfs) Primary OutFlow Max=0.88 cfs @ 12.11 hrs HW=308.95' (Free Discharge) L4=Culvert (Passes 0.88 cfs of 4.06 cfs potential flow) �2=0rifice/Grate (Orifice Controls 0.09 cfs @ 5.66 fps) 3=Sharp-Crested Vee/Trap Weir(Weir Controls 0.79 cfs @ 1.29 fps) Summary for Pond SMP2: Permeable Pavement InflowArea = 23,140 sf, 86.40% Impervious, Inflow Depth = 5.22" for 100yr event Inflow = 3.96 cfs @ 11.96 hrs, Volume= 10,065 cf Outflow = 3.20 cfs @ 11.95 hrs, Volume= 10,065 cf, Atten= 19%, Lag= 0.0 min Discarded = 3.20 cfs @ 11.95 hrs, Volume= 10,065 cf Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Peak Elev= 308.05' @ 12.01 hrs Surf.Area= 11,512 sf Storage= 230 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= 0.4 min ( 743.7 - 743.3 ) Volume Invert Avail.Storage Storage Description #1 308.00' 4,605 cf Custom Stage Data (Prismatic)Listed below (Recalc) 11,512 cf Overall x 40.0% Voids Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 308.00 11,512 0 0 309.00 11,512 11,512 11,512 Device Routing Invert Outlet Devices #1 Discarded 308.00' 12.000 in/hr Exfiltration over SurFace area Discarded OutFlow Max=3.20 cfs @ 11.95 hrs HW=308.03' (Free Discharge) L1=Exfiltration (Exfiltration Controls 3.20 cfs) Summary for Link AP-1: AP-1 Inflow Area = 160,547 sf, 46.23% Impervious, Inflow Depth = 1.00" for 100yr event Inflow = 6.24 cfs @ 12.06 hrs, Volume= 13,317 cf Primary = 6.24 cfs @ 12.06 hrs, Volume= 13,317 cf, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs 2021039 Post Development Type 1124-hr 100yr Rainfa11=6.20" Prepared by The LA Group Printed 6/15/2022 HydroCAD� 10.00-26 s/n 00439 O 2020 HydroCAD Software Solutions LLC Paqe 8 Summary for Link AP-2: AP-2 Inflow Area = 32,362 sf, 10.60% Impervious, Inflow Depth = 1.04" for 100yr event Inflow = 0.88 cfs @ 11.99 hrs, Volume= 2,814 cf Primary = 0.88 cfs @ 11.99 hrs, Volume= 2,814 cf, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Stormwater Calculations Previous Approval vs. Proposed Peak Discharge Rates Water Quality Volume Summary Previous Approval Versus Proposed Conditions Peak Discharge Rates Analysis Point AP-1 AP-2 Previous Proposed Previous Proposed Approval Condition Approval Condition Design Storm (cfs) (cfs) (cfs) (cfs) 10-Year 2.04 1.88 1.32 0.41 100-Year 6.36 6.24 2.36 0.88 Stormwater Practice Sizing Job Name and# YMCA Site Plan 2021039 Water Quality Volume Calculation 6/15/2022 WQv= [(P)(Rv)(A)]/12 Where: Rv=0.05 +0.009(I) I=impervious cover in percent P=90%rainfall (see Figure 4.1 in NYS Stormwater Management Design Manual) A=Area in acres Required WQv New Impervious %Impervious 100.00% Rv 0.95 90%Rainfall 1.15 *Area in Square Feet 11,129 WQv Required= 1013 ft3 0.023 ao-ft Tota1 = 1013 ft3 0.023 ao-ft Calcu lated WQv Infiltration Chambers (SMP-1) %Impervious 100.00% Rv 0.95 90%Rainfall 1.15 **Area in Square Feet 5,587 WQv Calculated= 509 ft3 0.012 ao-ft Porous Pavement(SMP-2) %Impervious 100.00% Rv 0.95 90%Rainfall 1.15 **Area in Square Feet 16,881 WQv Calculated= 1537 ft3 0.035 ao-ft Tota1 = 2046 ft3 0.047 ao-ft *Impervious area added because of site plan modification. **Additional impervious area being treated by practice because of site plan modification.