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 231 of 1493

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E_App E_Post-Development Model  NY-West Seneca 24-hr S1 10-yr Rainfall=3.14"
Prepared by Labella Associates  Printed 4/20/2026
HydroCAD® 10.20-7a s/n 09581 © 2025 HydroCAD Software Solutions LLC  Page 31

  Summary for Subcatchment PS-7:

Runoff  =  8.08 cfs @ 12.15 hrs, Volume=  0.638 af, Depth= 1.36"
  Routed to Reach DP-1 : Design Point

Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
NY-West Seneca 24-hr S1 10-yr Rainfall=3.14"

  Area (sf)  CN  Description
  245,856  80  >75% Grass cover, Good, HSG D
  245,856  100.00% Pervious Area

  Tc Length Slope Velocity Capacity Description
  (min) (feet)  (ft/ft) (ft/sec) (cfs)
  8.5  100 0.0450  0.20  Sheet Flow,
  Grass: Short n= 0.150 P2= 2.20"
  5.3  271 0.0148  0.85  Shallow Concentrated Flow, SCF
  Short Grass Pasture Kv= 7.0 fps
  0.2  20 0.1500  1.94  Shallow Concentrated Flow, SCF
  Woodland Kv= 5.0 fps
  14.0  391 Total

  Subcatchment PS-7:
  Hydrograph

  9  Runoff
  8.08 cfs
  8  NY-West Seneca 24-hr S1 10-yr
  Rainfall=3.14"
  7
  Runoff Area=245,856 sf
  6  Runoff Volume=0.638 af
  Runoff Depth=1.36"
  Flow (cfs)

  5  Flow Length=391'
  Tc=14.0 min
  4
  CN=80
  3

  2

  1

  0
  0  2 4  6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72
  Time (hours)

  Page 231 of 1493