2002-11-05_REVISION - M2001107 - Laserfiche WebLink

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NORTHERN COLORADO CONSTRUCTORS, INC. CLAY LINER PRELIMINARY SPECIFICATIONS AND AND OPERATION PLAN FOR NCCI PIT #1 General Conditions: Northern Colorado Constructors (NCCI) has provided to the Division of Minerals and Geology (DMG) a geotechnical engineering report by Terxacon, Project No. 21025057, dated May 14, 2002. This report states that testing indicates that the material below the gravel deposit at the NCCI Pit #1 site meets the criteria set forth in the DMG lined pit guide and that the material is suitable for construction a clay pit liner. Based on that information NCCI proposes to construct a clay liner in the pit as it is developed. NCCI proposes to follow the recommendations in the Terracon report and the following specifications and procedures for construction of the liner. The test by Terxacon indicate the material has fines in excess of 80% but in no case will the material used have less than 50% fines as described in the clay pit liner guide. The plasticity index as tested is between 15 and 29 in the material to be used. There is one test hole that did not meet this standard And the material from this area will not be used if tests when it is uncovered confirm this finding. There shall be less than 5% gravel in the material used for the fill. There shall be no rock larger than 2 inches in the fill material. The water content of the fill material shall be as close to optimum moisture as possible but in no case shall fill be placed with optimum moisture more than 1% drier or 3% wetter than optimum. The fill material shall be placed in a maximum of 9 inch lifts. The compaction shall be achieved by a minimum of 5 passes over the 9 inch lift with a 20 ton ox greater compactor. The number of passes may be lessened if it can be shown by testing that the desired compaction can be achieved with fewer passes on a regular basis. The lifts shall be bonded by disking the compacted surface before placing the next layer or by compacting with a tapered foot compactor with the feet long enough to penetrate the entire lift. The clay liner shall be keyed into the shale floor of the pit with a keyway at least 3 feet deep and 8 feet wide. The keyway shall be excavated to a depth at least 3 feet but must be dug to impermeable material in the bedrock. The keyway is then Filled with clay liner material according to these specifications. The clay liner shall be covered with ripped material from the borrow area to a depth of 2 feet to protect the liner from erosion. At the water level the shore shall be covered with 2 feet of pit run material to protect against wave action erosion.