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<br />Calculations <br />Case R K Ls C P A -Sediment Loss in Tons Comments <br /> per acrelyear <br />Pre-Mine Condition- ?6 0.37 0.?3 0.10057 1.0 0.160426$16 Data from Year 1999 <br />Sagebrush Community <br />based on Sagebrush <br />Reference Area <br />Post-Mine Condition- 26 0.37 0.?3 0.100400 1.0 0.41531464 ? Data Pram Year 1999 <br />Rangeland, vegetation <br />Areas 1-A and 1-? <br />Post-Mine Condition- 26 0.37 0.43 0.0884 ? l .0 0.365675 rata from Year 1999 <br />Rangeland, vegetation <br />1 <br />Areas ? <br />ConclusiOnS <br />The case results show that the erosion for the post-mining casein Vegetation Areas l -? and ? ?B are very <br />slightly cower than the pre-mining case. This coincides with actual observations over the last ?lo ye`ars?an the .. <br />sites, There has been effectively no significant rill erosion, no gullies and no sediment buil'd?p?.in the 2 ponds <br />over the entire bond release period. It is believed that these results are conservative since no ad?ustn?ent <br />factor for ponding was included in the "R" factor for the post-mine case although?some uneven settling in <br />the replaced overburden has undoubtedly resulted in slightly more ponding than that of the pre-mine <br />condition. <br />In comparing the pre-mine sagebrush community to Vegetation Sampling Area 2., the: sagebrush area is <br />.,higher in erosion due to the simple fact that herbaceous cover is better in Area Z ?44% vs. 31 ?o in the . <br />sagebrush area}, Also, a higher percentage of the cover is herbaceous in Area 2, which holds the soil better, <br />For this.reason, Vegetation Area 2 and all other areas draining into fonds ? and 2 pass the erosion standard. <br />Study Area I}escriptlan ? ; . ? ? ? -, ?_':::... . ?. `. <br />New Horizon Mine I is located in 5114, Sec. 25, T.47I?, R.16w anal the N11Z?, Sec, 36, T,47I?,? R,16w . <br />The reclaimed areas consist of three tracts of land far the purposes of vegetation sampling. Each area is <br />physically separated by a road or driveway. Area lA lies approximately in the E1IZ,??E1 ?A Sec.. 36, T. <br />47I?, R.16w and consists of 51.9 acres. Area 1 B lies approximately in the 1Vw114; N?114, See, 36, T. <br />47N, R,16W and the Nw114, Sec. 36, T.4?N, R,16V?' and consists of 7? acres. Area- 3? lies approximately <br />in the N11?, 5w114, Sw114, Sec. 25, T.47N, R.16'?V and consists of 6.?9 acres. Areas 1 Aand 1 B have <br />been reclaimed to dryland pasture and were sampled for vegetative cover by species. Area 3 is a hayland <br />pasture and was sampled for production. In addition,1999 and Zooo dryland pasture reference areas were <br />sampled far vegetative cover by species, Area 2 is a 67.9 acre area that was irrigated in 199+6 and is <br />therefore not part of this bond release. <br />Samp?c Paint Selection <br />Individual sample point locations were selected using pairs of randomly-generated coordinates. A 1996 <br />aerial photograph was brought into ESRI ArcView and a state plane 10o foot interval tic grid was <br />overlaid on the map. Coordinates located within a sample area were listed and exported to Microsoft