GENERAL49311

• Permit No: C1981038
• IBM Index Class Name: General Documents
• Doc Date: 6/25/1982
• Doc Name: COLO WESTMORELAND PHASE 2 SURFACE HYDROLOGIC STUDY STIPULATION 13 DRAINAGE REVIEW ORCHARD VALLEY
• From: MLR
• To: SANDY EMRICH
• Permit Index Doc Type: STIPULATIONS
• Media Type: D
• Archive: No

STATE OF COLORADO NiC HnRO D. LoMM fnvn~„~i
DEPARTMENT OF NATURAL RESOURCES
D. Monte Pascoe, Enecutive Director
MINED LAND RECLIAMA'TION
423 Centennial Building, 7373 Sherm n Street
Denver, Colorado 80203 Tel. (30~) 66-3567
June 25, 1982
TO: Sandy Emrich
FROM: Rich Domingue~~
RE: Colorado Westmoreland Phase 2 Surface
Stipulation No. 13, Drainage Review
Orchard Valley Mine
This review is broken into three parts. The first
presented by Pferrick & Co. for remedial actions on
second discusses other benches at the mine. Final.
rock pile is presented.
Ill IIIIIIIIIIIIIIII
999
David C. Shelton
Director
ogic Study
discusses the recommendations
the fan level bench. The
y, a discussion of the waste
It should be noted that the primary cause for conc rn addressed by Stipulation
13 is the stability of the fills at the mine and t e stability of the final
contours after mining and reclamation. The stabil~ty of these fills is greatly
affected by water content and, therefore, reducing the potential for saturation
of the fills is the major area of discussion prese ted in the report.
Fan Level Bench:
The major diversion system at the Orchard Valley M'ne is Located at the head of
the fan level bench. This diversion was designed o control the runoff from
what is termed the 'maximum probable thunderstorm'. Given this assumption, the
design of this channel far exceeds the requirement of the regulations regarding
diversions of overland flow (Rule 4.05.3).
Localized slumping along cut slopes associated wit' this channe3 has raised the
concern that the ditch may fail to adequately con y flow in the event that a
slump blocks the channel during a heavy runoff eve t.
The Merrick & Co. report provides two recommendati ns to reduce the hazard of
failure of this ditch. The first suggests improv ents to the ditch by laying
back the cut slopes and/or using rock bolts for buttressing.
While stability concerns are the overriding issue
prefer minimizing the amount of additional distur
action undertaken. Further, the suggested remedy
for improved stability by vegetative cover on the
suggests that serious effort be made to provide v
colluvi um exposed in the ditch cut slopes. Such
or excelsior matting to improve vegetative succes
contacted for further recommendations regarding v
here, the Division would
ante associated with remedial
does not address the potential
e cut slopes. The Division
getative cover on all areas of
fforts should include jute mesh
Sandy Emrich should be
qe to ti on establishment.
b