2007-06-01_PERMIT FILE - C1981019A ‎(21)‎

• Permit No: C1981019A
• IBM Index Class Name: Permit File
• Doc Date: 6/1/2007
• Doc Name: Attachment 1 to Attachment 12
• Section_Exhibit Name: Exhibit 07 Section 16 Pond 009A
• Media Type: D
• Archive: Yes

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COi.QWYO COAL. CQMPANY
tt(~A -SECTION 16
SEDIMENTATION POND SUMMARY
ORIGINAL. 1996 1998 2006 DIFFERENCE
CONFIGURATION STUDY STUDY DIFFERENCE STUDY 1998 TO 200$
ATERSNED AREA (acme};
Disturbed 0.0 0.0 OA 0.0
Postmining Topsoited and Seeded 25,0 80,3 55,3 32,1 -48.2.
Postmining Undietu?betl 38.0 32.9 -3,1 42.2 9.3
1-2 Year Rec~madon 33.5 27.1 -B.d 0,4 -27.1
3i YearRectamadon 78,0 69.9 -1$.i 94.4 34,5
Total Artta 172.5 200.2 27.7 '16$:7 -31.
POND PARAMETERS;
Bottom Elevation 7740.2 7740.2 7740.2 0.0 7740.7 0.0
Principal Spillway Invert Eievadon 7752.9 7752.0 7752.9 0.9 7752.9 0.0
Emergency Spillway Imrert Etevauon 7754.5 7754.5 7754.5 0,0 7754.5 0.0
Top of Embankmerri 7756.0 7755.0 7756.0 0,0 7756.0 0.0
StorageVOlumeBelowEmergencySpithvay{ac-ft) 5.31 5.31 5.31 0.40 5.4 4.t'
Storage Volume Below Principal 5ptltway (ac-R} 4,35 3.87 4.35 0.4$ 4.4 0.1
Prlrtcipat Spillway Parameters:
Type Drop Inlet Drop inlet Perf. Riser` Pert. Riser
Riser Diameter {in} 12.0 12.0 12.4 4.0 12.4 0.4
R[ser Ne[ght(ft} 9,2 $.3 9,2 4.9 9.2 0,4
Barrel Diameter (In) 12.0 12.0 12.4 0.0 12.0 0.0
Elevation of Podoratian(s} {ft) N/A NIA 7746,0 7746.0
Size of Perforation(s) {in) NlA NIA 4,4 4,0
Number of Perforatlons NIA WA 2 2.0
Emergency Spiihvay Parameters:
Typo Trapezodal Trapezoidal Trapezoidal Trapezoidal
Diameter (tn) NIA N/A N/A NIA
Bottom Width (ft) 20,0 20,4 19.0 -1,0 19.0 0.0
Length {ft} 15.4 15.0 17.0 2.0 17.0 0.0
SideSlapes'z'H:1V ft 2.0 3.0 2.4 -1.0 2A 0.0
MYDROLOGiCrttYDRAUUC PARAMETERS:
Base Ftow Rates (cfs) 3.00 OA3 -2.97 0,00 0,0
10-Year, 24-Hour Storm Event:
Precipitation (in) t.$ i.$ 0,0 1.8 0.0
Runoff Volume (ac-fl} 1.6 4,7 3,2 0.5 -4.2
Principal Spillway Peak Discharge (efs} 5.2 2.2 -3.1 0.4 -1.
Emergency Splt[way Peak Discharge {cfs) 0,0 0.0 4,0 0.0 0.4
Peak Surface Water Stage Elevation (ft} 7753.3 7752.4 -1,5 7745.2 -$.2
25-Year, 24-Hour Storm Event
Precipitation (In} 2.3 2.3 0,0 2.3 0.0
Runoff Voiuma {ac-ft} 2.7 7.5 4.9 1.7 -5.8
Principal Spillway Peak Discharge (cfs) 6.0 d.8 -i.2 1.0 -3.8
Emergency Spillway Peak Dtscharge {cts) 2.3 2.4 0.1 A.4 -2,4
Peak Surface Water Stage Elevation {ft) 7754,5 7754.8 0,0 7747.4 -7,2
Pond Freatruard (ft) 1.4 t A 4.0 8.5 7.2
SEDIMENT LOADING PARAMETERS:
Storm Predicted Peak Sefttabie Concentration {mui) OAO 0.00 OA 0.,00 0.0
Predicted Annual Sediment Loading {ac-ft) 0,17 0.24 0.07 0.16 X0.1
Available Sediment Storage Volume (aC-ft} 4.54 0.54 OAO 0.56 4.4
Maximum Sodimert Storage Etevadon {ft) 7743.7 7743.7 '7743.7 0.0 7743.7 4.0
Predkted Number of Store a Years 3,2 2:3 -0.9 3.4 1.2
Exh. 7-Sec16-15 Revision Date: 2/1/06
Revision No.: TR-63