PERMFILE102766

• Permit No: C1981032
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: CHAPTER S MITIGATION SUBSIDENCE CONTROL PLAN
• Media Type: D
• Archive: No

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Mr. Gerald McPhee
Northern Coal Company
P.O. Box 17583 7.A.
Denver, Colorado 80217
David C. Shelton
Director
January 27.1981 _..._.
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Re: Curtis Creek Crossing
Our File No. 78-345
Dear Mr. McPhee:
STATE OF COLORADO RIC nAPD D. L4MM. Gavc rn or
DEPARTMENT OF NATURAL RESOURCES
D. Monte Pascoe, Executive Director
MINED LAND RECLAMATION
423 Centennial Building, 1313 Sherman Street
Denver, Colorado 80203 Tel. [phone]
JAN 2 8 1981
With the receipt of your letter of January 6, 1981, in response to the remaining
concerns of Jim Pendleton and Roy Cox of our office, the Division finds that
the hydrologic and subsidence monitoring system for mining under Curtis Creek
is adequate. It is stipulated that a map locating the additional subsidence
monitoring points be forwarded to the Division prior to driving entries under
Curtis Creek.
As you know, the Division is concerned with Northern's inability to monitor
ground water wells due to the surface owner conflict. Northern should continue
to pursue a surface owner's agreement to gain access to monitor the wells. The
present monitoring system may not adequately characterize the hydrology of the
entire area affected by the Meeker area mines. Monitoring of ground water wells
will in all probability be necessary to make a determination of probable hydrologic
consequences as required by 4.05.13 of the Colorado Regulations and Section
34-33-110(2)(1) of the Colorado Surface Coal Mining Reclamation Act. Lack of a
complete monitoring system including data from ground water wells, may jeopardize
the attainment of Permanent Program permit approval for the Meeker area mines.
As previously agreed to in your letter of December 11, 1980, it will be incumbent
on Northern to initiate appropriate mitigation measures should monitoring in-
dicate that hydrologic problems (e.g. disruption of flows in Curtis Creek andjor
depletion of the Curtis Creek alluvial aquifer) are occurring. Northern should
be aware that in the undermining of Curtis Creek, monitoring wells would provide
an additional check, along with surface flow and mine inflow, as to the effect
of mining on the alluvial aquifer. Without groundwater monitoring, any significant
decreases in surface flow accompanied by increased mine inflows will be attributed
to a depletion of the aquifer as a result of mining activity. In the event of
interpretive problems, worst case assumptions will rule.