Southtowns Record

PBA07.09.2026packet

Government
Town of West Seneca
Board
Planning Board
Meeting
Jul 9, 2026, 6:00 p.m.
Posted by publisher
Jul 9, 2026
Kind
Agenda packet
Topics
Water, sewer and drainage, Housing, Zoning and land use, Roads and traffic, Parks and recreation, Budget and taxes, Public safety

Original document

Same meeting

Text · page 221 of 1493

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E_App E_Post-Development Model  NY-West Seneca 24-hr S1 1-yr Rainfall=1.82"
Prepared by Labella Associates  Printed 4/20/2026
HydroCAD® 10.20-7a s/n 09581 © 2025 HydroCAD Software Solutions LLC  Page 21

  Summary for Pond CH-1: Chambers

Inflow Area =  2.091 ac, 90.96% Impervious, Inflow Depth = 1.44" for 1-yr event
Inflow  =  4.80 cfs @ 12.04 hrs, Volume=  0.251 af
Outflow  =  1.18 cfs @ 12.29 hrs, Volume=  0.251 af, Atten= 75%, Lag= 15.4 min
Primary  =  1.18 cfs @ 12.29 hrs, Volume=  0.251 af
  Routed to Reach DP-1 : Design Point

Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Peak Elev= 592.38' @ 12.29 hrs Surf.Area= 0.127 ac Storage= 0.079 af
Flood Elev= 598.32' Surf.Area= 0.127 ac Storage= 0.433 af

Plug-Flow detention time= 60.5 min calculated for 0.251 af (100% of inflow)
Center-of-Mass det. time= 60.2 min ( 847.2 - 787.0 )

Volume  Invert  Avail.Storage  Storage Description
  #1A  591.25'  0.177 af  37.08'W x 149.10'L x 5.50'H Field A
  0.698 af Overall - 0.256 af Embedded = 0.442 af x 40.0% Voids
  #2A  592.00'  0.256 af  ADS_StormTech MC-3500 d +Cap x 100 Inside #1
  Effective Size= 70.4"W x 45.0"H => 15.33 sf x 7.17'L = 110.0 cf
  Overall Size= 77.0"W x 45.0"H x 7.50'L with 0.33' Overlap
  100 Chambers in 5 Rows
  Cap Storage= 14.9 cf x 2 x 5 rows = 149.0 cf
  0.433 af  Total Available Storage

  Storage Group A created with Chamber Wizard

Device  Routing  Invert  Outlet Devices
  #1  Primary  591.25'  8.0" Round Culvert
  L= 25.0' CPP, projecting, no headwall, Ke= 0.900
  Inlet / Outlet Invert= 591.25' / 591.00' S= 0.0100 '/' Cc= 0.900
  n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf

Primary OutFlow Max=1.18 cfs @ 12.29 hrs HW=592.38' TW=0.00' (Dynamic Tailwater)
  1=Culvert (Inlet Controls 1.18 cfs @ 3.38 fps)

  Page 221 of 1493