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Topsoil Replacement Thickness. The topsoil balance as of December 31, 2011 for the <br />remaining life -of -mine is calculated as follows: <br />Mine Area <br />Total disturbance area <br />Permanent Facilities & Topsoil replaced <br />Disturbance area requiring soil <br />Soil in stockpiles (Table 11.1) <br />Mean replacement depth available <br />= 848.6 acres <br />= 818.5 acres <br />= 30.1 acres <br />= 41.2 acre -feet <br />= 2.3 feet (28.1 inches) <br />By dividing the topsoil available by the area requiring topsoil replacement, we arrive at the <br />future topsoil balance thickness of approximately 2.3 feet for the remaining disturbance area. <br />This generalized topsoil balance does not account for any area variations or for permanent <br />facilities not requiring topsoil; it is strictly an area -wide average. <br />During 2007, topsoil thickness sampling was conducted over the topsoiled area on a 500 ft. <br />grid. The overall topsoil replacement depth for the areas reclaimed to date is 21.4 inches. <br />The 21.4 inches is right in line with the original projections of 21.6 inches. <br />REVEGETATION <br />• Seeding and Shrub Planting <br />Seeding. No additional acres were seeded for the first time in 2011. However, 8.3 upland <br />acres were re- seeded in the North Pit area as a result of constructing surge ponds, re- <br />constructing drainage channels, and conducting rill and gully maintenance. These areas are <br />shown on the 2011 Chronologic Seeding Map. <br />Table 11.2, Seed Mix No.1- Upland Sites and Ephemeral Drainages, presents the approved <br />upland seed mix. Seed tags from the seed bags used is contained in the attachment 2011 Seed <br />Tags. <br />Shrub Planting. 500 Narrowleaf cottonwoods and 1,230 Coyote willows were planted in the <br />riparian areas along Annand Draw near the junction with the North Pit and Neck Pit in 2011. <br />These were evenly distributed between the 2010 (1.2 acre) fenced shrub plot, the 2007 (2.6 <br />acre) fenced shrub plot and the 2003 (4.5 acre) unfenced shrub plot. <br />• Monitoring <br />ESCO Associates, Inc conducted revegetation monitoring of permanently revegetated areas <br />during the summer of 2011. The 2011 Annual Revegetation Monitoring report will be <br />submitted under separate cover. <br />• Weed Control <br />Survey for noxious weeds was carried out on the Yoast Mine permit area in 2011. Monitoring <br />was conducted in 2011 to determine the need or level of retreatment necessary for areas <br />sprayed in 2010. Canada thistle was the primary target species in all control areas, with lesser <br />