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16% more topsoil and subsoil will be salvaged in Pit No. 2 than was previously stated by Kerr Coal. B. Pit No. 1. Kerr's plan For topsoil salvage in the Pit No. 1 area raised several questions as to whether this plan would provide an adequate plant growth medium for the reclaimed area. Several potential problems were identified with respect to excessive topsoil erosion due to high slopes, reduced in- filtration due to soil dispersion, lowered permeability leading to possible drought conditions, and the possible formation of impermeable layers between the topsoil and spoil. Factors con- tributing to these problems were the slopes in exvess of 30%, the sodic, high clay content of the spoil directly beneath the topsoil, and the fact that only 6 inches of topsoil was to be salvaged due to an extremely high clay content on the subsoil. Kerr Coal resolved the problem by proposing to selectively remove specific overburden material from Pit No. 3 and replace that material as subsoil in the Pit No. I area. This plan is described in detail in revised pages 780-3ccccccc, 780-IOccccccc, 780-68bbbbbbb, 780-68ccccccc, 816-I4aaaaaaa, 816-14bbbbbbb, 816-124aaaaaaa, 816-I24bbbbbbb, 816-183aaaaaaa, 816-138bbbbbbb, and new Table i8, Pit No. 3, Selected Overburden Handling Plan. The issue of excessive topsoil erosion due to the 30% slopes was resolved after Kerr Coal explained that slope lengths are reduced through the use of contour furrows along the side slopes of Pit No. Z. 3. Kerr Coal has requested permission to leave tcpsoil ir. place within the impoundment area of sediment ponds. It is this Division's position that such areas constitute "disturbed areas" (Rule 1.04(36)), therefore topsoil salvage is required by Rule 4,06. Leaving topsoil in place within the ponds can potentially result in deleterious effects to the soil, of concern to this Division. The primary effects which might be expected are the following: A. The wetting and drying cycles to which the soil in the pond would be exposed can increase the concentration of sodium and soluble salts in the topsoil, due to upward movement in the soil by capillary action. B. If the runoff water contains large amounts of sodium, this will lead to increased dispersion of the clays in the topsoil, thus greatly limiting any leaching or dcwnward movement of sodium or soluble salts. Therefore, most of the water would evaporate, leaving the salt load in the pond. Upon drying, this would be followed by upward movement of salts and sodium by capillary action. Data from Wyoming Fuels and some from Xerr indicatrs that the 50 dram content of surface runoff may have a medium- high sodium hazard, therefore resulting in a medium to high cnance of concentrating sodium in the topsoil over time C. The chemistry of the sediment cahich collects in the pond may such as to result in contamination of the topsoil. Aside from contributions of salt and sodium, there is a potential for con- centration of heavy metals through physical transport and colloidal adsorption. The analyses of the overburden submitted by Kerr -20-