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Section 780.18(6) Continued. <br />Samples will be composited for each distinct stratigraphic unit with <br />a minimum compositing interval of four feet for thinly bedded strata <br />and a maximum compositing interval of twenty feet for thick <br />relatively uniform strata. Composite samples will be analyzed for <br />pH, texture, calcium, magnesium, sodium, and SAR and ESP will be <br />calculated from resulting values. <br />If the supplemental sampling/analyses proposed indicate a significant <br />potential for sodium toxicity, Kerr will proceed with a second phase <br />of sampling. Any necessary secondary sampling will be designed to <br />evaluate the effectiveness of mixing in mitigating the effects of <br />isolated zones of potentially deleterious material on overall spoil <br />suitability. Secondary sampling will involve collection of spoil <br />samples on 200 foot centers with sampling from the regraded spoil <br />surface to a depth of at least four feet. Any necessary secondary <br />sampling will be initiated immediately upon completion of initial <br />backfilling and regrading in Pit 2. If secondary sampling is <br />indicated, a minimum of four regraded spoil samples will be collected <br />and analyzed for the same parameters previously designated for <br />primary sampling. <br />Selective spoil handling will be necessary only if significant <br />potential for sodium toxicity is indicated by primary sampling and <br />secondary sampling indicates that mixing is not effective in <br />achieving overall spoil suitability. If sampling results far Pit 2 <br />dictate the need for selective handling, Kerr will develop and submit <br />a technical revision describing selective handling plans for MLRD <br />review and approval. <br />Topsoil and Subsoil Redistribution Plan - Kerr Mine Area <br />Prior to the reapplication of topsoil and subsoil, the backfilled <br />overburden will be graded along the contour to minimize erosion, <br />assure stability, minimize slippage and ensure that a suitable root <br />penetration zone is created, as described in Section 816.102 (e). In <br />780-70 aaaaR <br /> <br />Revised - January, 1991 <br />