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III IIIIIIIIIIIIIIII ~ <br />DIVISION OF MINERALS AND GEOLOGY <br />Dcperuncnl of Naluml Resuurces <br />1313 Sherman St. Room 215 <br />Denver. Colorado 80203 <br />Phone: (30}1 866-3567 <br />FA%:(}071832-8106 <br />September 7, 1999 <br />Mr. John Lohr <br />Southdown Co., Inc. <br />P.O. Box 529 <br />Lyons, CO 80 540 <br />RE: Report on Storage of Cement Kiln Dust at the Southdown inc. Lyons Plant, Lyons Quarry, <br />Perrnit No. #M-77-208 <br />Dear Mr. Lohr, <br />DIVISION O F <br />MINERALS <br />GEOLOGY <br />REC LAMA710N <br />MIN IN G•SA FETY <br />8,11 Owens <br />Governer <br />GregE Watcher <br />Executme Onector <br />Michael B. Long <br />OrY1Swn DrrCCbr <br />This letter is being written to address technical issues which need clarification in the recent report <br />submitted by Banks & Gesso on behalf of Southdown Co., Inc., addressing the storage of Cement <br />Kiln Dust (CKD) in C-Pit at the Lyons Quarry, Permit No. #M-77-208. Under the current permit, <br />the Operator is allowed to store CKD in this pit. After a consultation with the Division of <br />Minerals and Geology (DMG) in January 1999, the Operator agreed to do chemical leach tests on <br />the CKD and submit data and hydrological modeling of the pit, so that DMG could evaluate the <br />potential impacts of CKD storage on the local groundwater. DMG has been responsible for <br />evaluating the impacts of mining activities on groundwater quality since 1992, and it was <br />believed that a review of the current permit conditions was necessazy in order to confirm that all <br />concerns were being addressed. <br />Having received [he requested report from Banks & Gesso on June 23, DMG personnel have <br />reviewed the document and have a few concerns which still need to be addressed. Attached is the <br />review of the report by Harry Posey. Please address the following questions: <br />1) [n section 5.0, Geologic and Hydrogeologic Setting of the Disposal Area, reference is made <br />to the vazious shale and limestone layers underlying and abutting C-Pit. Please clarify <br />whether the source of this information is the NRCS soil survey, and whether the distances <br />which these formations extend to the alluvium have been taken from this report or from field <br />measurements. <br />• <br />STATE OF COLORADO <br />2) In section 7.2, Simulation of the Potential Quantity of Leachate, it is stated that two models <br />of the site conditions were simulated, both of which assumed a closed disposal site. Since the <br />site will remain open for several years while CKD is still being deposited in the pit, DMG <br />