PERMFILE52028

• Permit No: C1981020A
• IBM Index Class Name: Permit File
• Doc Date: 5/13/2002
• Section_Exhibit Name: Appendix M‎(i)‎ to M‎(viiI)‎
• Media Type: D
• Archive: Yes

LOMA COAL LOADOUT

I. RUNOFF AND VOLUMES
Determine•
Maximum runoff area and peak discharges
Reservoir liquid volume
Reservoir sediment volume
Total reservoir volume
Area:
5.21 Acres in strips parallel to DRGW between Highway 13;
and Irrigation Culvert to NW.
Precipitation:
P10 = 1.4 inch(es) (10-year, 24-hour precipitation event from
the Precipitation-Frequency Atlas of the Western
United States, Volume III - Colorado)
Use CN average = 87
Assume Antecedent Moisture Condition (MC) II
s = 1000 - 10 (SCS Method) F
`~ CN
s = 1000 - 10 = 1.49
87
Runoff:
Q10 = (P10 - 0.2 S)2 = [1.4 - 0.2 (1.49 = 0.47 inch
P 10 + 0.85 1.4 + 0.8 (1.49
q - Qp (Ad)(Q)
q = hydrograph coordinate discharge in cfs (cubic feet per second)
qp = csm/inch (cubic feet per second per square mile per inch of
runoff)
Ad = drainage area in square miles
Q = runoff in inches
Assumptions: 1. Time of Concentration approximately 0.25 Hrs.
2. Time of Travel approximately 0
3. Drainage Area 5.21 Acres = 0.008138 square miles