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Section 816.24 (b) Continued. <br />i <br />i <br />growth needed for the proposed postmining land use. (Schuman and <br />Power, 1980, in a paper entitled, "Plant Growth as Affected by <br />Topsoil Depth and Quality on Mined Lands", demonstrated the signi- <br />ficant value of as little as 2 inches of topsoil.) Redistribution <br />of soil will be conducted along the contour across all regraded <br />sites, including the necessary recoiling in all drainage ways. <br />Potential compaction of both overburden and topsoil will be allevi- <br />ated through regrading topsoil using either a dozer or rubber tired <br />blade. Grading of overburden was reported by Farmer and Richardson <br />(1976) to significantly reduce bulk densities at the Western Energy <br />Mine in Montana. Also, frost action and wetting and drying will <br />loosen most compacted zones to a depth of 20 inches even in soils <br />with high clay content, as documented by Shafer et. al., EPA, <br />1979. <br />Wind and water erosion on applied topsoil prior to seeding will be <br />minimized by the crust that forms on soils containing clays such as <br />those found in the permit area. Researchers in North Dakota have <br />documented that mixing of the topsoils as a result of their place- <br />ment by scrapers significantly reduces their susceptibility to wind <br />erosion. Gee, et. al., (1978) reported that the amount of erosion <br />caused by wind on fallowed farm ground was 119 metric tons per <br />hectare per year. Placement of these soils in topsoil stockpiles <br />reduced their erodibility to 90 metric tons and replacement of <br />these same stockpiles onto leveled spoil further redacted thelr <br />erodibility to 76 metric tons per acre. As explained by Bauer, et. <br />al., (1976), the sealing was a result of higher silt and clay <br />fractions in the soil material levels which are present in the mine <br />area soils. (Table 42, Soil Chemical and Physical Parameters Lab <br />Analysis Kerr North Area). The evaporation of moisture from the <br />topsoil results in a surface seal that effectively prevents wind <br />erosion. Leaving the topsoil in a roughened condition until seed- <br />816-25 <br />