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<br />Proposed Decision -North Thompson Creek/Phase II Bond Release <br />November 26, 1993 <br />Page 4 <br />900 feet west of the No. 1 Mine and is situated at the same elevation and aspect. The <br />fan portal is on a slope above another drainage southwest of the mine site. <br />Vegetation data collected during 1991 and 1992 by the operator were evaluated to <br />determine if the vegetative cover was at least 90% of the cover in the adjacent reference <br />area. The 1991 data characterized the site by life form components of vegetative cover. <br />These data indicate that the vegetative cover on the refuse area, the No. 1 Mine and the <br />No. 3 Mine are statistically equivalent. Therefore, the three areas were considered as one <br />parcel for purposes of evaluation of 1992 cover data by species. No cover data by <br />species was collected on the fan portal site. <br />According to the 1992 data in the mine permit, vegetative cover in the reference area <br />was 46.9%. Vegetative cover on the disturbed mine area (refuse area, No. 1 Mine and <br />No. 3 Mine) was 44.1 %. Evaluation of the data in the permit indicates the cover on the <br />mine site is more than 90% of the cover of the reference area with 90% statistical <br />confidence. Therefore, the vegetative cover on the mine area meets the definition of <br />acceptable cover required by Rule 4.15.8(3). <br />The 1992 data indicate that 43.5% of the relative cover on the mine site consists of <br />Agropyron cristatum (crested wheatgrassl. The next most prevalent grass, E/ytrigia <br />repens (quackgrassl, comprises only 1.7°,6 of the relative cover. Astraga/us cicer <br />(milkvetch) accounts for 42.3% of the relative cover. The next most prevalent forb, <br />Eucepha/us g/aucus (aster), accounts for only 2.0% of the relative cover. A number of <br />other grasses and fortis, as well as woody plants, are present on the reclaimed area. <br />However, they are a minor component of the vegetative community in terms of relative <br />cover. <br />The mine site was seeded five and six years prior to 1992 when the cover data discussed <br />above was collected. The species composition of the community in 1992 does not indi- <br />cate that the reestablished community is near the approved diversity standard in the mine <br />permit. Based upon the competitive nature of the introduced grasses that presently <br />dominate the site, it is probably not reasonable to assume that the community will evolve <br />such that the desired diversity will be expressed. There is also no indication that the forb <br />component of the community is approaching the diversity standard. <br />If the reestablished vegetation does not develop into the diverse community required by <br />the mine permit, some alternate form of management or reseeding practices will need to <br />be implemented in the future. Reseeding all or part of the mine would probably return the <br />area to a condition in which vegetative cover success standards are not met and where <br />sediment contributions from the disturbed area exceed contributions from adjacent undis- <br />turbed areas. In that case, the area would not meet the regulatory requirements for a <br />Phase 2 bond release. Therefore, based upon the lack of diversity in the reestablished <br />vegetative community, the Division proposes to deny the requested bond release for the <br />mine area. <br />