REV98734

• Permit No: C1989074
• IBM Index Class Name: Revision
• Doc Date: 10/13/1993
• Doc Name: RIMROCK STRIP MINE PN C-89-074 RIMROCK COAL CO TR 7 ENGLEVILLE GULCH SAE DRILL SITE SAE AND ROAD
• From: DMG
• To: LANDMARK RECLAMATION INC
• Type & Sequence: TR7
• Media Type: D
• Archive: No

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STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
pe~co~
Department of Natural Resources

1 313 Sherman SL, Room 215
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Denver, CO 80207
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Phone: [phone] re ~c
FAX: IJ031 83 2-81 06 Roy Romer
Governor
October 13 , 1993 Michael B. Long
Division Director
Mr. Mark Kerr
Operations Manager
Landmark Reclamation, Inc.
4901 S. Windermere Street
Littleton, CO 80120
RE: Rimrock Strip Mine, Permit No. C-89-074, Rimrock Coal Company,
TR-07, Engleville Gulch SAE, Drill Site SAE and Road Diversion
Ditch, Adequacy
Dear Mr. Kerr:
The Division has reviewed the October 6, 1993 submittal for TR-07 and
has the following questions or comments:
1. The Sedcad run for the SAE's shows an area of zero acres. As a
result, there is zero runoff and zero settleable solids. It
appears that a minimum acreage of .O1 acres is required for Sedcad
to analyze settleable solids. Please rerun Sedcad with at least
the minimum acreage.
2. A slope of 20~ is used for the Sedcad run for Engleville Gulch.
This corresponds to a slope of about 11 degrees. My recollection
is that slope approaches 45 degrees (100 slope). Please justify
the use of a 20~ slope.
3. A K value of .23 was used in the Sedcad runs for SAE's #1
(Engleville Gulch SAE) and #4 (Drill site SAE). However, from
"Soils of Colorado" by the SCE, 1983, ayon soil has a K value
ranging from .15 to .24 and capulin soil has a K value of .43 for a
soil depth of 10 inches. An average value would appear to be about
.29 for a 10 inch soil depth. On page 19 of Section 2.05.3(4), a
K value of .37 was used for calculating the sediment load going
into the pond. Please justify a K value of .23.
4. For the haul road diversion ditch, a curve number of 74 was used
for undisturbed land. However, in the permit, page 3 of Section
2.05.3(4), a curve number of 77 is recommended for brush and a
curve number of 80 is recommended for pinyon-juniper. The Sedcad
run for an average curve number of 78 still works for the diversion
ditch design so no changes need to be made.
5. Please supply page numbers and a permit section number so that the
TR-07 designs can be placed into the permit.
6. Please provide written responses to the adequacy letter of
September 23, 1993.