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<br /> <br />Coulson Excavating Company, Inc. -Bonser Gravel Pit <br />Exhibit E -Reclamation Plan <br />The overall goal in choosing a liner material is to obtain minimal hydraulic conductivity. Benson et al., <br />1992, have shown empirical relationships with respect to hydraulic conduMivity between plasticity index, <br />percent fines, and clay content. The ranges of hydraulic conductivities for the above three factors are <br />shown in Table 1. <br />Tablel <br />Empirical Relationship Range OfHydrauGc Conductivity (R/day) <br />Plasticity Index (as measured) / <br />Hydraulic Conductivity <br />%Fines (as measured) / <br />Hydraulic Conductivity <br />Clay Content / <br />Hydraulic Conductivity <br />5.6x10 to 8.4x10-0 <br />2.9x10 to 2.9x10' <br />2.9x I Ob to 5.7x 10-5 <br />In the same paper, Benson et al. also correlated plasticity index with clay content. With a plasticity index <br />of 24, clay content can vary between 20-40%. This content is sufficient enough to facilitate a low <br />hydraulic conductivity after compaction. Daniel (1990) recommends a plasticity index of at least ] 0 for a <br />material to be suitable for lining. In addition, Daniel and Koerner (1993) suggest a minimum of 50% fines <br />for a suitable liner material, and with 95.ti% fines, the soil sample material exceeds this criteria. <br />Liner Desi~/Specifications <br />The liner is to be constructed with weathered Pierre shale from the Bonser pit. The moisture content <br />during construction will be IS% to 18% (1% dry of optimum or 2% wet of optimum). This content is <br />under the plastic limit, and will allow the soil to remold to a homogenous low conductivity material. <br />Liner material will be laid down in two lft. lifts. A 35,000 lb. Caterpillar 316 sheep's-foot roller will <br />compact each lift of soil. Each foot on the roller measures 12 in. The roller covers 20% of the ground with <br />each pass, requiring four passes over each lift to ensure complete compaction. Full penetration of the <br />sheep's-foot ensures bonding of the two lifts. After the liner has been compacted, subsoil and topsoil will <br />be placed on top of the liner. This will be the final design configuration. <br />