Laserfiche WebLink
topsoil samples and four (4) backfill spoil samples for 2005 were collected from within the <br />New Horizon 2 area. The topsoil samples were collected by a hand auger and the backfill <br />• samples were collected from the sidewalls of four foot deep pit excavated with a rubber <br />tired backhoe or from a 4 foot deep soil auger hole. Each backfill sample site consists of <br />two subsurface samples, one of the 0 to -2 ft interval and one of the -2 to -4 ft intervals. <br />Sample identifiers are given the suffix A and B, respectively. <br />Topsoil and spoil samples are shipped to Servi-Tech Laboratories in Hastings, NE for <br />analysis. The analytical results (see Attachment 2005-B) indicate that all samples are <br />suitable. No additional grading, special handling, or amendment application is needed. <br />Soil Redistribution <br />In general, the topsoil that was used for redistribution is live handled from ahead of the <br />active mining area to the awaiting backfill area. Because the material is moved by mine <br />equipment and is scheduled amongst the other mining functions, discrete topsoil <br />campaigns as done in the past are no longer conducted. Occasionally, mining parameters <br />require that some topsoil be stockpiled adjacent to a laydown area prior to spreading. <br />Soil Thickness <br />The thickness of soil replaced during 2005 was verified byfour sample sites. Sample sites <br />for the New Horizon 2 mining area were selected systematically utilizing a 467 foot by 467 <br />foot grid pattern. Sites at New Horizon 2 were determined from CAD drawings using <br />distances and azimuths from established survey points and located in the field by a <br />handheld GPS unit. <br />A 2-3/4 inch bucket auger was used at each site to excavate a pilot hole through the entire <br />soil strata. An abrupt boundary, defined by color and rock fragment content, typically <br />occurred at the soil/spoil interface. The replaced soil thickness was measured through the <br />pilot hole immediately after encountering the spoil. Minor Revision # 44 was approved by <br />DMG in August 2000. The revision, based on years of extensive sample analysis, allowed <br />for a reduction in the parameters for which the soil is analyzed. <br />Soil thickness as determined by past sampling is shown on Exhibit 2005-6. Soil thickness <br />information for each sample site is located on the map. The average topsoil thickness of <br />the 2005 sampling season is approximately 1.5 feet. The New Horizon 2 has a minimum <br />requirement of 0.8 feet for topsoil placement. Attachment 2005-A lists the topsoil analysis <br />as required by our permit. <br />New Horizon 2 has many different soil thickness requirements as shown on Exhibit 2005-8, <br />which is in section 2.05.4-4 of the current permit. This shows the type and area of the <br />reclaimed land. <br />Soil Salvage and Storage <br />All suitable soil has been salvaged ahead of mining at New Horizon 2. Approximately <br />77,368 cubic yards (Pre 1995 LIFT 2), 18,643 cubic yards (Pre 1995 LIFT 1), 38,293 cubic <br />yards (Pre 1995 MIXED) and 311,050 cubic yards (2005 LIFT1), a total of 445,354 cubic <br />• yards of soil are stored in stockpiles at the end of 2005 as shown on Exhibit 2005-10 (2005 <br />Topsoil Balance Map). The soils were separately stockpiled by soil types as specified by <br />our permit. <br />