2013-01-14_PERMIT FILE - M2012032 ‎(6)‎

• Permit No: M2012032
• IBM Index Class Name: Permit File
• Doc Date: 1/14/2013
• Doc Name: RESPONSE TO STORMWATER ADEQUACY COMMENTS
• From: GREG LEWICKI & ASSOCIATES
• To: DRMS
• Email Name: TC1
• Email Name: TAK
• Email Name: RCO
• Media Type: D
• Archive: No

DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
MEMORANDUM
STATE OF COLORADO
COLORADO
D I V I S I O N O E
RECLAMATION
MINING
— &—
SAFETY
John W. Hickenlooper
Govemor
Mike King
Executive Director
Loretta Pineda
To: Bob Oswald Director
From: Tim Cazier, P.E. 1t
Date: January 10, 2013
Re: Permit No. M- 2012 -032, Revenue Mine Surface Water Systems Designs;
Soil Unit 112 Details Response
The Division of Reclamation, Mining and Safety (DRMS) engineering staff has reviewed the
January 9, 2013 letter addressing the selected hydrologic soil group (HSG) for soil unit (SU) 112
prepared by Greg Lewicki And Associates (GLA).
Based on the discussions presented in the letter and delineations presented in Figure 1, attached
to the letter; the Division accepts GLA's assertion that the undisturbed, vegetated areas in the
soil survey's SU 112 (Cryorthents -Rock outcrop) should be HSG C. Subbasins SWB -2 and
SWB -4 are nearly completely vegetated as delineated in Figure 1 and the Division accepts the
proposed curve numbers (CN). The Division also accepts GLA's assertion to use HSG C for the
vegetated areas of SWB -1 and SWB -3. However, both these subbasins include significant areas
of "bare rock" as delineated in Figure 1.
SWB -3 appears to have well more than 50 percent of the area delineated as bare rock. This
needs to be factored in to the weighted composite CN. The Natural Resource Conservation
Service (NRCS) does not have a CN designation for bare rock and/or scree, Division suggests a
CN of 88 or 89 (Natural desert landscaping or Open space - Poor condition, both HSG D as
discussed in the soil survey).
SWB -1 has a significant area in the southwest, upper elevations delineated as bare rock, as well
as an unvegetated area (in the SU 129 — B) in the north, lower elevation that is not delineated as
bare rock, but might be historic mine waste. These areas should also be factored into the
weighted CN.
In summary, the Division accepts the assertion that vegetated areas in the SU 112 be considered
HSG C. However, significant bare rock and unvegetated areas need to be factored into the
weighted CN.
If either you or the applicants have any questions regarding the comments above, please call me
at (303) 866 -3567, extension 8169.
Office of Office of
Mined Land Reclamation
Denver • Grand Junction • Durango Active and Inactive Mines