Southtowns Record

5A.-ENGINEER'S REPORT

Government
Town of Aurora
Board
Town Board
Meeting
Feb 4, 2026
Kind
Other
Topics
Water, sewer and drainage, Zoning and land use, Public safety

Original document

Same meeting

Text · page 255 of 351

Read the whole document on one page (all 351 pages, each with its own heading)

WNY-2500056.00_HydroCAD  extreme_precip_tables_output (29) 24-hr S1 25-yr Rainfall=3.85"
Prepared by Greenman-Pedersen, Inc  Printed 12/18/2025
HydroCAD® 10.20-7a s/n 04560 © 2025 HydroCAD Software Solutions LLC  Page 180

  Summary for Pond SWALE: SWALE

Inflow Area =  0.280 ac, 64.29% Impervious, Inflow Depth > 2.95" for 25-yr event
Inflow  =  0.79 cfs @ 12.03 hrs, Volume=  0.069 af
Outflow  =  0.51 cfs @ 12.35 hrs, Volume=  0.058 af, Atten= 35%, Lag= 18.6 min
Primary  =  0.51 cfs @ 12.35 hrs, Volume=  0.058 af
  Routed to Pond RCVR 1 : RCVR 1

Routing by Dyn-Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs
Peak Elev= 901.39' @ 12.28 hrs Surf.Area= 1,307 sf Storage= 1,170 cf

Plug-Flow detention time= 128.3 min calculated for 0.058 af (84% of inflow)
Center-of-Mass det. time= 62.0 min ( 845.6 - 783.6 )

Volume  Invert  Avail.Storage  Storage Description
  #1  900.00'  2,104 cf  Custom Stage Data (Prismatic) Listed below (Recalc)

Elevation  Surf.Area  Inc.Store  Cum.Store
  (feet)  (sq-ft)  (cubic-feet)  (cubic-feet)
  900.00  396  0  0
  901.00  1,038  717  717
  902.00  1,736  1,387  2,104

Device  Routing  Invert  Outlet Devices
  #1  Primary  900.68'  8.0" Round 8" HDPE L= 32.0' CPP, mitered to conform to fill, Ke= 0.700
  Inlet / Outlet Invert= 900.68' / 900.55' S= 0.0041 '/' Cc= 0.900
  n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf

Primary OutFlow Max=0.54 cfs @ 12.35 hrs HW=901.38' TW=901.22' (Dynamic Tailwater)
  1=8" HDPE (Outlet Controls 0.54 cfs @ 1.84 fps)