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samples, each representing a two-foot depth increment, will be collected by or under the <br /> supervision of a soil scientist from a 60 degree slant grid system with 300-foot centers. <br /> The vertical sampling increments will be 0.0 to 2.0 feet and 2.0 to 4.0 feet. The soil <br /> scientist will also inspect the surface spoil between grid points. If a significant <br /> change in spoil characteristics is observed between grid points, additional sample sites <br /> will be located. Regraded spoil will also be visually inspected for compaction, possible <br /> root growth problems, and the potential for slippage at the topsoil/spoil interface. The <br /> lateral and vertical sampling intensities will be more closely evaluated once sufficient <br /> samples are collected to determine the degree of sample variability as recommended by Lang <br /> et al ., 1985. This sampling program will ensure that the top four feet of regraded spoil <br /> is non-toxic and chemically/physically suitable to enhance plant growth. <br /> Regraded spoil samples will be analyzed for the following parameters to determine spoil <br /> suitability: pH, acid base potential, particle size (texture), saturation percent, EC, <br /> and SAR. The parameter list is based upon the baseline information acquired during the <br /> premine overburden sampling program (Tab 6). The parameter list will be more closely <br /> evaluated once sufficient samples are collected to determine the degree of sample <br /> variability. This approach will help to eliminate unnecessary and unwarrantable analyses <br /> cost and data duplication. This parameter list represents those characteristics of the <br /> Nucla and Nucla East overburden and interburden which may affect plant growth on regraded <br /> spoil. Laboratory procedures and suitability criteria will be identical to those <br /> described in Tab 6, Attachment 6-1, Tables 6-1-2 and 6-1-3. <br /> Unsuitable. Spoil Mitigation Plan. If one or more parameters fall within the unsuitable <br /> range at a given grid point, a three-part mitigation plan will be implemented. <br /> 1. The area around a suspect hole will be sampled on a closer spacing interval in order <br /> to better define the lateral extent and variability of the unsuitable material. <br /> 2. In those areas where specific geochemical or physical problems are encountered, the <br /> regraded spoil will be mechanically loosened and mixed by ripping, chiseling, or <br /> approved alternate forms of scarification. The major advantages of scarification are <br /> related to the physical properties of the spoil. The topsoil and spoil are scarified <br /> to decrease compaction, increase aeration and water movement, and increase plant <br /> rooting depths (Josiah, 1986). Increased water movement may, to some degree, allow <br /> more downward leaching of carbonates. Therefore, although the greatest benefits of <br /> scarifying are related to the physical soil properties (density, porosity), a lesser <br /> geochemical benefit (increased rate of carbonate leaching due to increased water <br /> 21-6 Revised 04/11/88 <br />