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The contention by KCC that the possible high SAR overburden materials will not <br />be impacted by mining is false. One has to just look at Maps 12a and 13a <br />(Geologic Cross Sections f and G, respectively) and note the dip of the rock <br />beds to know that the mine pit will indeed intersect those possibly high SAR <br />strata. <br />b. As noted in the Kerr response, the Division incorrectly located <br />drillholes 028-79-12 and 028-79-14c in the Pit 3 area, when they <br />actually were in the 720 Pit area. In addition, as 2.5 million cy <br />of Pit 1 material is being backfilled to the 720 Pit, Kerr should <br />prepare for mitigation if necessary. Thus, KCC should sample <br />overburden backfilled into the 720 Pit to ensure that sodic <br />material will be kept at least four feet below the final reclaimed <br />surface, as approved in TR-07 for Pit 1, and develop a mitigation <br />plan as appropriate. <br />Colorado Mined Land Reclamation Division does not have guidelines for <br />overburden suitability determinations at this time. We believe that ESP is a <br />better determination of sodium hazard in materials, such as overburden, that <br />are not presently in equilibrium with their environment. SAR then may be a <br />more accurate determination of sodium hazard in materials, such as topsoil, <br />that are more or less in equilibrium with their environment. It is also <br />obvious, from side by side comparison of ESP and SAR values of the samples, <br />that the ESP values were somehow calculated from other numbers than the SAR <br />values. <br />c. Please provide the raw sodium milliequivalent per 100 grams of soil <br />values that must have been used to calculate the ESP value on the <br />Overburden Analysis Tables so the Division can check their accuracy. <br />d. The Division assumes that the units used for the Cation Exchange <br />Capacity (C .E.C.) column were milliequivalents per 100 grams of <br />material. Is this correct? <br />The Carter Mining Company (CMC) study (Lindsey, 1987) that KCC cites to back <br />up its contention that truck and shovel operations mix overburden has been <br />reviewed by the Division. We agree that substantial mixing of overburden will <br />occur with the mining methods used by KCC. We do not agree that this mixing <br />will necessarily alleviate all the problems identified in the overburden. <br />Review of the CMC study revealed the conclusion that mixing does not always <br />alleviate problems associated with the overburden (see the conclusion that <br />relates to organic carbon). Wyoming DEQ did require that Carter Mining <br />Company confirm their conclusions with a pre-topsoiling sampling program. <br />Data collected to date through 1989 did verify the conclusions of the study. <br />However, to ensure that revegetation will be timely and in compliance with the <br />regulations, the Division requests that Kerr sample the sodicity of the <br />rooting zone in a similar manner. <br />The Division has some additional related questions on future overburden <br />sampling. Pages 780-70aaa and 780-70aaaa present an overburden sampling plan <br />for the Pit 2 area. The Division is concerned about the proposed spacing of <br />drillholes, the compositing interval and the parameter list. <br />-2- <br />