2608 Sp Recharge Calculations

Job: Sheet No. Calc by: Check by:

Sharon Hills 1 of SCS Date Date

1 11/7/2008

Recharge Calculations Required Recharge Volume Hydrologic Soil Group

Proposed Impervious Area (sf)

A B C D Sum:

21,240 0 92,693 653,050 766,983 17.61

X

Target Depth Factor (in)

=

0.60 0.35 0.25 0.10 sf ac

Required Recharge Volume (cf) 1,062 0 1,931 5,442 8,435 cf 0.19 af

Capture Area Adjustment Pond 7 Discharges

Storm 1 2 10 25 100

Primary Discharge (cfs) 9.54 15.99 24.31 25.12 26.62

Secondary Discahrge (cfs) RECHARGED 4.26 5.88 8.32 10.05 10.76

Total Discharge (cfs) % Recharged 13.8 30.9% 21.87 26.9% 32.63 25.5% 35.17 28.6% 37.38 28.8% Ave= 28%

Impervious Areas Contributing to Pond 7 Sub. Area (ac) P-18 0.46 P-19 0.34 P-20 3.85 P-21 0.27 P-23 5.00 ROOFS 0.30 TOTAL= 10.22 TOTAL X AVE % TO RECHARGE= Impervious to Re2= Impervious to Re3= Total= 3.28 Total Impervious Area: Area contributing to Recharge systems: Adjustment factor: 17.61 3.28 Adjusted volume: 8,435

2.87 0.34 0.07 17.61 ac 3.28 ac

65%=

=

5.36

x

5.36

=

1 and 100 Year Storm Infiltration Volume (TR 20 w/HydroCAD) Volume Infiltrated from Rainfall 1 year (af) 100 year (af) Re1 4.62 5.36 Re2 0.07 0.19 Re3 0.02 0.04 Total 4.71 5.59 In the 1 year storm, 4.5 times the recharge volume is infiltrated In the 100 year storm, 5.4 times the recharge volume is infiltrated

11.45 ac 33%

45,230 cf 1.04 af

Job: Sheet No. Calc by: Check by:

Sharon Hills 2 of SCS Date Date

Drawdown Calculations Time=

System 1 Rv=

Rv (K)(Bottom Area)

233,482 cf Bottom Area=

K=

Time= 47.8 System 2 Rv=

47.8 hours <

8,276 cf Bottom Area=

System 3 Rv=

OK

K=

2.41 in/hr

20.3 hours <

1,742 cf Bottom Area=

72

OK

K=

2.41 in/hr

590 sf

Time= 14.7

72

2,027 sf

Time= 20.3

2.41 in/hr

24,336 sf

14.7 hours <

72

OK

2 11/7/2008