2010-09-07_HYDROLOGY - C2009087 - Laserfiche WebLink

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Peabodq Peabody Energy Colorado Coal Resources, LLC x o NO se01J1 ion o' ??L D? Vmin9 -and Sam Mr. Jason Musick Environmental Protection Specialist Colorado Division of Reclamation, Mining and Safety 1313 Sherman Street, Room 215 Denver, Colorado 80203 August 31, 2010 RE: Proposed Bedrock Monitoring Well, Peabody Sage Creek Mine Dear Mr. Musick: 701 Market Street St. Louis, Missouri 63101-1826 314-342-3400 -PeabbdySage`Cre-e4Z Mirie-(PSCNT)`proposes-te-instail-another monitoring-well-this-year to ---- --°° - augment baseline groundwater information that will be required for mining Federal coal reserves that are within the existing permit boundary but are outside of the approved 5-year mine plan. PSCM is currently involved in permitting activities to secure the rights to mine the Federal coal further to the northwest within the permit area under an LBA application with the BLM. PSCM understands the Division will require additional groundwater information for baseline purposes from these more distant reserves before any plans to mine beyond the 5-year permit term are approved. PSCM is planning to install a new monitoring well at the location shown on the attached map entitled "CCU039 Proposed Monitoring Well Location Map". This location coincides with exploration hole ccu039 drilled in 2009. Detailed lithology descriptions and down-hole geophysical logs collected at ccu039 will provide accurate information for developing monitoring well completion details. The site is also just outside and down-gradient of the northwestern edge of future bedrock mining based on existing drill hole data and seismic fault mapping. PSCM believes groundwater monitoring data collected here will provide sufficient baseline information down-gradient of any future mining proposed within the PSCM permit boundary. The site is readily accessible from the two-track county road RCR 51D. PSCM is proposing to only monitor the Wadge Overburden at this location for the following reasons: Robson and Stewart of the USGS maintain the thin sandstones and coal aquifers that make up the lower member of the Williams Fork Formation seem to function as a single hydrologic unit in the eastern part of their study area (page 54, Water-Resources Investigations Report 90-4020). Both the Wadge Coal and Wadge overburden are part of the basal Williams Fork aquifer, and the eastern part of the study area coincides with the proposed location of the proposed bedrock monitoring well. • Monitoring wells COV23 (Wadge Overburden) and CW23 (Wadge Coal) constructed within the PSCM permit area monitor deep groundwater down-gradient of mining approved for the 5-year mine plan. Both wells exhibit similar water level elevations and seasonal variations (see Section 2.04.7, PSCM Permit Application Package). Both the overburden and coal units within the PSCM permit area exhibit similar sodium