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1 <br />in August 1992. Subsequent work has been maintenance work related to sediment <br />control structure maintenance, and weed control. <br />• Description of Boud Release Amount Request: All final reclamation work was <br />completed by September 1992. Initial concerns and observations related to backfill <br />compaction were addressed and /or repaired. Subsequent observations have not shown <br />further compaction or settling of the backfilled material on the bench or highwall. <br />Based on field observations of the CDMG staff and independent contractors, the bench, <br />access road, and facilities area have been successfully bacfilled and graded. Since the <br />site has been mined since 1905, backfilling and grading requirements were slighlty <br />different for this mine site than for other sites mined after August 3, 1977. The <br />backfilling and grading of this site comforms to the requirements of Rule 4.14.1(2)(f) <br />and the CDMG approved backfilling and grading plan of December 15, 1989. In <br />backfilling the highwall, bench area and access road, all reasonably available spoil <br />material was used to backfill the highwall. The material was obtained from berms <br />along the bench outslope and material originally spoiled downslope during the original <br />operation of the mine (pre-1977). The remining exposure of the highwal comprises <br />approximately five feet of a fifty foot highwall. The remaining exposure is consistent <br />with adjacent sandstone exposures along the dissected mesa and has been graded to <br />facilitate drainage un a natural manner, while minimizing erosion and sedimentation. <br />The backfilled slopes aze compatible with the post-mining land use of grazing <br />(rangeland). Prior to backfilling, CDMG and Rocky Mountain Bank and Trust <br />evaluated the stability of the backfill configuration and agreEd that the conficuration <br />• would be stable. Highwall stability has been demonstrated by the lack of slumping, <br />significant compaction, or significant erosion. Through the backfilling, the coal seam <br />and all potentially combustible materials were covered. Mine openings were sealed in <br />compliance with the approved plan. Downslope spoil placed prior to August 3, 1977 <br />and not needed to achieve the final topography was left in place to prevent further <br />erosion and potential instability of the backfilled material above. Two maps have been <br />provided which illustrate the pre-reclamation and post-reclamation configurations of the <br />La Plata No. 1 Mine bench and access road area. These maps are based on data <br />compiled by the CDMG during surveys of the mine area. Based on the maps, the <br />backfilled topography, and field observations since 1990, the L.a Plata No. 1 Mine is <br />eligible for Phase I bond release. <br />With the establishment of the permanent vegetation on the reclaimed slopes, surface <br />erosion has been minimized and there was no evidence of active rills and gullies during <br />field work in August 1995. Vegetation on the site has been well established for at least <br />two yeazs and the vegetation sampling data indicates the successful establisment of a <br />diverse permanent vegetation community of the same seasonal nature and variety as <br />surrounding native and rangeland communities. Vegetation cover and species <br />composition data from 1995 quantitative sampling demonstrate successful establishment <br />of revegetation, the initial criteria for Phase II bond release. Erosion and sediment <br />generation at the site are negligible, as can be observed by the lack of rills, gullies or <br />other erosional features. Based on the quantitative vegetation sampling and analysis, <br />• and the SEDCAD+ computer modelling for hydrology and sedimentology, Rocky <br />Mountain Bank and Trust believes the site satisfies all criteria for Phase II bond <br />release. <br />2 <br />