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material will be placed to within 6 inches of the surface and the final 6 inches will be filled with topsoil. The plug drawing is presented in Exhibit 26 B, NW Mains Ventilation Shaft Plug. • hollowing removal of structures and equipment and plugging and sealing of the shaft; road surfacing materials, geotextile, and culverts will be removed and disposed of ofisite; and the shaft pad and access road disturbance areas will be regraded to reestablish effective drainage and blend with the surrounding terrain. Stockpiled and windrowed topsoil will then be replaced on those disturbed azeas where it was previously removed and seeded with a pastureland seed mixture. In reference to the thickener underflow project, the reclamation work will involve removal of the pump, hosing and piping, pump platform, support beams, powerline and poles, transformer, concrete pad and grounding bed. The pump will be removed from the pit along with salvageable components and then the remainder of the platform and support beams will be dozed into the pit. The powerline and poles and transformer will be salvaged and the concrete pad will be dozed into the pit. The grounding bed will be disconnected and left itrplace and covered during the backfilling and grading of the surrounding area. The area then will be topsoiled and seeded in conjunclion with the reclamation of the entire portal/facilities azea. Soil Stabilization Plan Proper site preparation and soil handling strategies will be utilized to control wind and water erosion. The movement and manipulation of topsoil materials in a moist condition minimizes wind and water erosion. As explained by Bauer et al. (1976), a protective surface seal develops as silt and clay fractions bond together after reapplication of topsoil. This phenomenon is attributable to the rapid evaporation of surface moisture from redistributed soil materials. Disturbed areas will be subjected to final grading, but will remain in a rough condition to assist stability and resist slippage of topsoil after reapplication. Leaving the graded surface in a roughened configuration also improves • moisture permeability between the spoil/topsoil interface (Bauer et at. 1976). Scrapers will reapply topsoil along the contour whenever possible. The tracks made by scrapers create a "terracing" effect that helps to reduce overland surface flow and the potential loss of topsoil. Following topsoil reapplication, but before seeding, the topsoil will be graded to insure a uniform and stable thickness which will be consistent with the reclamation and revegetation requirements. Prior to seeding, which will be initiated as soon as practical after final grading, topsoiled sites will be chisel-plowed in order to alleviate compaction and promote water infiltration. Chisel-plowing has been a highly effective means of temporary stabilization prior to vegetation establishment. Dollhopf et al. (1977) reported that chisel-plowed topsoil at the Savage, Beulah and Colstrip Surface Mines were only surpassed by the radical treatment of dozer basins in reducing overland water flow from reclaimed mine sites. The water detention capacity of chisel-plowed topsoil is reported by Dollhopf et al. (1977) as 176,400 liters per hectare, or 2,521.3 cubic feet per acre. Another stabilization technique which serves to minimize erosion is contour furrowing. Disturbed land within the proposed permit area will be contour furrowed following seeding. Atypical cross section of a contour furrow is depicted in Figure 12, Design of Typical Contour Furrow. According to data derived from studies at the Energy Mine No. 1, the water detention capacity of these furrows, when spaced thirty feet apart, is 2,599.7 cubic feet per acre. u TR 02-40 2.05 - 106 I /7/02