2004-08-11_REVISION - M2000156 (2)

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Coulson Excavating Company, Inc. - Bonser Gravel Pit Exhibit E -Reclamation Plan will extend down 1 foot into the weathered shale for a total depth of 5 feet. The well will be constructed with 4-inch drain the that will be backfilled with gravel. The drain the will be tied in to pumps that will serve to de-water the pit during construction of the compacted liner. Construction of the liner will not begin until the pit is completely dry. A backhoe will then be used to dig a trench or keyway into bedrock. Weathered shale will be backfilled and compacted into the keyway as described below. Weathered Pierre shale removed from the pit bottom will then be placed along the embankments to construct the pond liner. The weathered Pierre shale will most likely require ripping prior to removal for ease of construction. Approximately 18,000 cy of weathered Pierre shale will be placed in two 1-foot lifts. A dozer will be used both for ripping and pushing the shale over to the embankments for placement. A sheep's-foot roller will compact each 1-foot lift to 95% of maximum density as determined by the Standard Proctor test. Maintaining the proper moisture content will be critical to ensure adequate compaction, and therefore, the moisture content of the soil will be tested just prior to compaction of the first lift. ASTM Method D-4643 will be used to determine field moisture content. It is expected from earlier field moisture content measurements that field moisture conditions are 3-4% wetter than optimum. The lift will be allowed to dry to the optimum moisture content before compaction begins. The field inspector will calculate the drying rate as the day progresses and measure the field moisture content. Water will be added or lifts will be allowed to dry as needed to maintain the optimum moisture content throughout the compaction process. The volume of water needed to raise the moisture content by 1 % has been calculated to be approximately 5,400 gallons per acre. This calculation is given in Appendix I, as well as a step-by-step calculation procedure for the same calculation with different acreage. Appendix II contains tables for 0.5-5 acre 1-foot lift water volumes and estimates of water losses throughout the day for each month of the year. Evaporative soil water loss tables were calculated based on a rate 30% greater than pan evaporation. Pan evaporation for the area is 40 inches per year (NOAH, 1982). The 30% increase is due to albedo effects (Hillel 1980). The water loss tables are to be used as a general guide to estimate the amount of water to have on site to moisten liner material if it becomes too dry, or to estimate the amount of time the lift needs to dry if the material is too wet. Moisture content measurements are to be used to estimate moisture loss and to determine how often moisture content measurements should be made. For example, if the soil needs to lose 3% moisture content before compaction, and the field personnel determines from the charts in Appendix II that it should take about 1.5 days to evaporate that amount of soil moisture under clear skies, then moisture content measurements should be made at the end of the first day and every few hours during the second day.