2017-03-20_PERMIT FILE - C1981019 ‎(27)‎

• Permit No: C1981019
• IBM Index Class Name: Permit File
• Doc Date: 3/20/2017
• Doc Name: Coal Stockpile Pond Design Information
• Section_Exhibit Name: Volume 18 Exhibit 7-23 Figure J-2
• Media Type: M
• Archive: No

Site Preparation:
Prior to placing fill,the area should be stripped of organic topsoil or other deleterious materials.
Acceptable Fill Materials:
Suitable fill materials can be obtained from pond excavations or from nearby borrow sources. Suitable materials include native clay soils,clayey sand soils,and bedrock materials which are broken down to these soil types(SC, CC, CL and CH). Bedrock materials should be
0 processed to produce a soil like material with maximum particle size of 6 inches. The materials used as embankment fill should have at least 25 percent fines (material finer than No.200 sieve). The field engineer may approve the use of other materials following appropriate
laboratory testing.
Unacceptable Fill Materials:
Materials not considered suitable for use as embankment fill include cleaner sand and gravel. Also unacceptable are highly carbonaceous materials obtained from bedrock excavations or well-cemented sandstones which do not break down to soil like material. Highly organic soils or
materials containing construction debris are also not acceptable. Frozen soil is not acceptable.
Fill Placement and Compaction:
Embankment fill should be placed in thin horizontal lifts(8 to 12 inches loose thickness). The fill should be moisture conditioned to within 2 percent of optimum moisture content and compacted to at least 95 percent of standard proctor maximum dry density(ASTM D 698). The
placing and spreading of fill materials should be started at the lowest point of the embankment.Fill placement and compaction should be observed and tested b qualified eotechnical engineering firm.
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Monitoring and inspections:
C,okk Monitoring and inspections should be performed by qualified individuals as outlined in Colorado DRMS regulations 4.05.6 and 4.05.9.
Construction Notes:
Se 1. See Exh. 7-23 Figure J1 for general location and associated drainage areas.
2. Hatched area below the spillway outlet shall be riprapped with 12 inch median size material.
7240 7240
Waterline to
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7230 7230
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0
7220 7220
_... �_ Riprap installed -
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minus 12", NWL Elev. 7218 t7
722a 15.o cu.yds.
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72j6
-" 721°
7210 7210
0+00 0+50 1+00 1+50 2+00 2+50 3+00 3+50 4+00 4+50 5+00
� �0 CROSS-SECTION THROUGH IMPOUNDMENT Impoundment
O HORIZONTAL SCALE 1" =50' Premine Topography : q«"^
s VERTICAL SCALE 1" =10'
Nigh Water Line
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7250 7250
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Area - Capacl'ty Table
a
7210 7210
1230
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0+00 0+50 1+00 1+50 2+00 2+50 3+00 3+50
CAPACITY
ELEVATION AREA AVERAGE AREA
INCREMENTAL CUMULATIVE
72 (Feet) (Acres) (Acres) ( ) (Acre-Feet)Acre-Feet
) impoundment
7210.0 0.81 0.0 CROSS-SECTION THROUGH IMPOUNDMENT Premine Topography
0.$4 0.$4 HORIZONTAL SCALE 1 =50 High Water i e _.
7211.0 0.87 0.84
VERTICAL SCALE 1 -10
g
E 0.90 0.90
7212.0 0.93 1.74
7213.0 0.99 0.96 0.96 2.70
7214.0 1.05 1.02 1.02 3.72 01
� ��2
1.08 1.08 �A aeon,
7215.0 1.11 4.80 ReG�a ek
7216.0 5.95 ►1
1.18
7217.0 1.24 1.21 1.21 7.16 N
1.31 1.31
�4
7218.0 1.31 8.44
TOTAL CAPACITY 8.44 ACRE-FEET(DESIGN)
w. ---
ENGINEER'S CERTIFICATION
I, THOMAS C. PETERSON, being a W E
Licensed Professional Engineer in TR-108
the State of Colorado, do hereby Approved 3/20/17
'`----- Note: This is a containment pond designed to completely store the runoff from a 10 year,2'4 hour storm from the entire certify that this map has been
drainage area. Pond must be maintained with a water surface below elevation 7214.8 to contain the 10 year storm. reviewed by me and is true and
correct to the best of my knowledge
Legend Hydrologic Desi n Storm Calculations
and information relying on work
g performed by others, and based on S
Design Drainage Area Watercourse Elevation Curve Peak Runoff information supplied by experts
Permit Boundary Event (acres) Length Difference No. Precip. Inflow Volume identified in section 2.03.3 of the
High Water Line
(mi) (ft) (CN) (in) (cfs) (ac-ft) Colowyo Coal Company L.P. Permit. Page Exh. 7-23J-5
10-Yr, 24-Hr 346.4 0.77 300 See Exh. 7-23 Fig.J1 1.80 11.4 1.39 Coal Stockpile Pond
Section Through Dam ,�� 25-Yr, 6-Hr 346.4 0.77 300 See Exh. 7-23 Fig. J1 2.30 78.8 6.16 ♦`������� /��II
F
Note:Runoff volumes and peak inflows for this structure were calculated by SEDCAD program. ���♦ �� L
Compacted Fill `� o pF..••ti��i Design Information
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Sediment Yield Calculations 225 z SCALE: As Noted
Rlprap Rainfall Rainfall Annual 3 7
'O . };' \ DATE: --_1213012016
Source Area Factor Factor Sediment Sediment Sediment Sediment One Year r •
(ac) storm storm Into Pond Out of Pond Stored Ra/Rs Sediment Sediment Yield D,� •.•��� i?.��<v�" DRWG.BY. TCP
Contour interval is 2 ft within pond area. Rs (tons) (tons) (tons) ( )( ) (ac-ft) �` •..06 �� COAL APPROVED BY:
(Rs) (Ra) (tons) SS �� ♦� S�F COMPANY
Contour interval elsewhere is as noted. i / E ♦ `� E,Y DRWG NO.
,, ONAL ♦` �'EOPLE.PRODUCT IO`1..E�F'R
�` ter'°` 346.4 14.9 19.0 949 0.0 949 1208 0.71 I� v
.�. Exh. 7-23
Note:Sediment calculations were determined using SEDCAD program. Colowyo Mine
., g A 9 THOMAS C PETERSON 5731 State Highway 13 Figure J2
kA i)vo OL6
001
See SEDCAD model for individual watershed sedimentology parameters. P.E. No. 32257 Meeker,CDIOrado81641 g
50' 0 50' 100' For these calculations sediment density was assumed to equal 78 Ib/cu ft.
1 1 3 f l 7 No. REVISION DATE BY CHK
Coal Stock He Pond DATE
TR-108 New Drawing 111/17 TCP TT
Scale 1 = 50' Exh 7-23 Fi J2PondDesi nR1.dw
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