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6.4.5 Exhibit E - Reclamation Plan <br />Laboratory Maximum Dry Density = 108.9 pcf <br />Modified Proctor- Optimum Moisture Content = 13.9% <br />Laboratory Maximum Dry Density = 117.7 pcf <br />The overall goal in choosing a liner material is to obtain minimal hydraulic <br />conductivity. Benson et al., 1992, has shown empirical relationships with respect <br />to hydraulic conductivity between plasticity index, percent fines, and clay content. <br />The ranges of hydraulic conductivities for the above three factors are shown in <br />Table 6.4.4-4. <br />Table 6.4.4-4. <br />Empirical Relationship Range Of Hydraulic Conductivity <br /> (feet/day) <br />Plasticity Index (as measured) and 5.6x10 to 8.4x10 <br />Hydraulic Conductivity <br />% Fines (as measured) and Hydraulic 2.9x10- to 2.9x10 <br />Conductivity <br />Clay Content (20-40%) and Hydraulic 2.9x10 to 5.7x 10`5 <br /> <br />In the same paper, Benson et al. also correlated plasticity index with clay <br />content. With a plasticity index of 24, clay content can vary between 20-40%. <br />This content is sufficient enough to facilitate a low hydraulic conductivity after <br />compaction. Daniel (1990) recommends a plasticity index of at least 10 for a <br />material to be suitable for lining. In addition, Daniel and Koerner (1993) suggest a <br />minimum of 50% fines for a suitable liner material, and with 95.6% fines, the soil <br />sample material exceeds this criterion. <br />Liner Design Specifications <br />The liner is to be constructed with weathered Pierre shale from the Bonser pit. <br />The moisture content during construction will be 15% to 19% (-1 % dry of <br />optimum or +3% wet of optimum). This moisture content is slightly above the <br />plastic limit, and will allow the soil to remold to a homogenous, low-conductivity <br />material. The liner is specification includes three zones, an uncontrolled fill zone <br />or dewatering gap, a compacted clay liner zone and a protective cover zone. <br />The liner shall be keyed into the shale to a depth of 4 ft or to practical refusal. <br />The typical cross section is shown in Exhibit F. A protective cover to prevent <br />against significant wave action erosion is specified for the eastern shoreline due <br />to the easterly direction of the prevailing high wind events (see Exhibit F). The <br />protective cover shall be composed of rock with a D50= 1" and a thickness of 8". <br />The native gravel has a D50> 1" and will therefore be used for the slope <br />protection. The slope protection sizing calculation is given in Exhibit E-