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0 <br /> .DTSCOTT, COX&ASSOCIATES, INC. consulting engineers • surveyors <br /> February 21, 1991 <br /> Mr. Bruce Humphries RECEIVED <br /> State of Colorado <br /> Department of Natural Resources FEB 2 2 1991 <br /> Mined Land Reclamation Board <br /> 215 Centennial Building Mined Land <br /> 1313 Sherman Reclamation Division <br /> Denver, CO 80203 <br /> Ref: 89185 <br /> Marshall Pit MLRB Permit M-89-041 <br /> Deepe Pit MLRB Permit No. M-81-302 <br /> Request for Technical Revisions <br /> Dear Mr. Humphries: <br /> As we discussed on the phone with Mr. Dan Hernandez on February 8, 1991, <br /> the purpose of this request is to make technical revisions to both the Marshall <br /> Pit MLRB Permit No. M-89-041 and the Deepe Pit MLRB Permit No. M-81-302. <br /> The purpose of both technical revisions directly relate to the proposed change <br /> in the final grade elevations on the Marshall Pit Reclamation. The approved <br /> plan called for placing sediments and waste slurry from the processing of <br /> materials mined on the Marshall Pit site back on the Marshall Pit site for final <br /> reclamation purposes. The proposed plan, that will be detailed in greater <br /> depth herein, also calls for placing additional waste slurry materials, from <br /> miring operations on the Deepe Pit site back on the Marshall Pit site for final <br /> reclamation purposes. The attached revised reclamation plan for Marshall Pit <br /> shows the proposed new contours for the additional slurry materials as well <br /> as showing in the profile the previously-proposed and the newly-proposed <br /> reclamation contours. <br /> Recent revisions in estimated mining rates have determined that available <br /> materials from the Deepe Pit site during the allowable Marshall Pit slurry <br /> filling period will be approximately 38,000 cubic yards short of the quantities <br /> needed to match the grades shown on the attached plans. The current plan <br /> calls for placing approximately 165,000 cubic yards of slurry on site (this <br /> quantity is the maximum available from Deepe Pit and Marshall Pit during <br /> the filling period). The original Marshall Pit Plan called for placing <br /> approximately 57,000 cubic yards of slurry material on-site in the approved <br /> Marshall Pit Reclamation Plan. <br /> The extra slurry material will be generated from mining operations on the <br /> Deepe Pit site. The amount of slurry material that will now be deposited in <br /> 1530 55th Street • Boulder,Colorado 80303 0 (303)444-3051 <br />