APPCOR11885

• Permit No: C1981046
• IBM Index Class Name: Application Correspondence
• Doc Date: 8/29/1985
• Doc Name: SUNLIGHT MINE TR FN C-046-81 ADEQUACY COMMENTS
• From: MLRD
• To: JEFF DECKLER
• Media Type: D
• Archive: No

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DEPARTMENT OF NATURAL RESOURCES
Davitl H. Getches, Executive Director
MINED LAND RECLAMATION DIVISION
DAVID C. SHELTON, Director
Richard D. Lamm
Governor
DATE: August 29, 1985
T0: Jeff Deckler
FROM: Candice Thomps
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RE: Sunlight Mine Technical Revision, File No. C-046-81, Adequacy Comments
After review of the above-referenced technical revision, the following
adequacy concerns have been identified.
Sedimentation Ponds - Rule 4.05.6
Sediment Pond B is designed for a depth of 1.65 feet. This does not allow for
the required freeboard of one foot between the top of the embankment and the
required volume to store the ten-year, 24-hour event and the sediment volume.
The lower surface facilities area slopes toward the Four Mile Creek. How will
runoff be routed to Sediment Pond B?
Since further disturbance is requested at the lower facilities area, the
100-year event should be estimated for the Four Mile Creek at the mine site.
The capacity of the natural stream with resulting flood depths should then be
evaluated with the floodplain delineated. A berm would be required if the
flood depth would overtop the facilities area. The most accepted manner for
estimating the flow resulting from a 100-year event for streams with drainage
areas of this size is Technical Manual #1 of the Colorado Water Conservation
Board entitled "Manual for Estimating Flood Characteristics on Natural -Flow
Streams in Colorado." The period of record for the gaged site on Four Mile
Creek is not of sufficient length to give a valid statistical recurrence
event.
Haul Roads - Rule 4.03.1
On Map 1, the haul road grade from survey elevations 130 feet to 150 feet is
24%, exceeding the 15% maximum grade allowed for haul roads. In order for the
Division to allow a variance from this maximum grade, a demonstration will
need to be made by the applicant detailing the requirements of Rule
4.03.1(1)(e). The overall grade from the bottom to the top of the haul road
is 9%, an acceptable grade.
Will the existing road need to be widened for coal haulage, and if so, will
deeper cut slopes be required? If so, the requirements of Rule 4.03(3)(c)
will need to be addressed.
423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. [phone]