PERMFILE114929

• Permit No: C1982056
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 08c‎(1)‎ EMD Treatment Pond Design
• Media Type: D
• Archive: No

APPENDIX A
Design Calculations
Primary Spillway Capacity: 8-inch HDPE pipe, 700' in length and 40' drop
Assume: Flowing 3/4 full = > A3/4 = 0.8 A~ fl = 0.2793 ft2
dactual = 0.75D A = 0.3491 k2
R= A/P, P= D= 3.1416(8/12) = 2.094 k
Rig = 0.3491 k2/2.094 f[ = 0.1667 ft
R3/4 = 0.91 R~ = 0.91(0.1667 ft) = 0.1517 ft
S =40'/700' = 0.0571 n = 0.009
Q = 1.49/n ((A)(R)2/3(5)1/2)
Q = 1.49/0.009((0.2793)(0.1517)2/3(0.0571)1/2) = 3.1438 cfs = 1411 gpm
Emergency Spillway Capacity: 6-inch HDPE pipe, 150' in length and 10' drop
Assume: Flowing 3/4 full = > A3/4 = 0.8 All = 0.1571 ft2
dactual = 0.75D A = 0.1963 ft2
R= A/P, P= D= 3.1416(6/12) = 1.571 k
• R~ = 0.1963 k2/1.571 ft = 0.1250 ft
R3/4 = 0.91 R~ = 0.91(0.1250 ft) = 0.1137 ft
S = 10'/150' = 0.0667 n = 0.009
Q = 1.49/n ((A)(R)2/3(5)1/2)
Q = 1.49/0.009((0.1571)(0.1137)"/3(0.0667)1/2) = 1.5758 cfs = 706 gpm
Inflow from Borehole Dewatering = 350 gpm
Inflow from 10-year, 24-hour precipitation even[ = 1.7 inches x Pond Surface Area =
1.7/12 (80x180) = 2,106 ft3 = 15,081 gallons
Assume total precipitation From event falls in 1 hour = > 15,081 gallons/60 minutes = 251.3 gpm/cell
A total inflow rate of 502.6 gpm will occur for both cells due [o the 10-year, 24-hour event.
Total Inflow =Borehole Inflow + 10-year,24-hour event Inflow = 350 gpm + 502.6 gpm = 852.6 gpm
Primary spillway capacity flowing 3/4 full is greater than total inflow, 1411 gpm > 852.6 gpm
Total Inflow per cell =Borehole lntlow +251.3 gpm = 350 +251.3 =601.3 gpm
Emergency spillway capacity flowing 3/4 full is greater than total inflow per cell, 706 gpm > 601.3 gpm
Total Available Storage Time per cell = (Pond Storage Volume -Storm Volume)/Borehole Inflow
Rate = (966,003 gallons - 15,081 gallons)/350 gpm = 2,717 minutes = 45.3 hours per cell