REV07907 - Laserfiche WebLink

Home Browse Search

D_ escription of Bond Release Amount Request: All final reclamation work was completed by September 1992. Initial concerns and observations related to backfill compaction were addressed and /or repaired. Subsequent observations have not shown further compaction or settling of the backfilled material on the bench or highwall. Based on field observations of the CDMG staff and independent contractors, the bench, access road, and facilities azea have been successfully backfilled and graded. Since the site has been mined since 1905, backfilling and grading requirements were slightly different for this mine site than for other sites mined after August 3, 1977. The backfilling and grading of this site conforms to the requirements of Rule 4.14.1(2)(f) and the CDMG approved backfilling and grading plan of December I5, 1989. In backfilling the highwall, bench area and access road, all reasonably available spoil material was used to backfilt the highwall. The material was obtained from berms along the bench outslope and material originally spoiled downslope during the original operation of the mine (pre-1977). The remising exposure of the highwall comprises approximately five feet of a fifty foot highwall. The remaining exposure is consistent with adjacent sandstone exposures along the dissected mesa and has been graded to facilitate drainage in a natural manner, while mininuzing erosion and sedimentation. The backfilled slopes aze compatible with the post-mining land use of grazing (rangeland). Prior to backfilling, CDMG and Rocky Mountain Bank and Trust evaluated the stability of the backfill configuration and agreed that the configuration would be stable. Highwall stability has been demonstrated by the lack of slumping, significant compaction, or significant erosion. Through the backfilling, the coal seam and all potentially combustible materials were covered. Mine openings were sealed in compliance with the approved plan. Downslope spoil placed prior to August 3, 1977 and not needed to achieve the final topography was left in place to prevent further erosion and potential instability of the backfilled material above. With the establishment of the permanent vegetation on the reclaimed slopes, surface erosion has been min;m;~ed and there was no evidence of active rills and gullies during field work in 2002 and 2003. Vegetation on the site has been well established for ten yeazs and the vegetation sampling data indicates the successful establishment of a diverse permanent vegetation community of the same seasonal nature and variety as surrounding native and rangeland communities. Vegetation cover and species composition data from 2002 and 2003 quantitative sampling demonstrate successful establishment of revegetation achieving the vegetation cover standazd set for the site by CDMG. Erosion and sediment generation at the site aze negligible, as can be observed by the lack of rills, gullies or other erosional features. Based on the quantitative vegetation sampling and analysis, Rocky Mountain Bank and Trust believes the site satisfies all criteria for Phase III bond release. Notice to Parties Identi5ed in Rule 3.03.2(1): Please see attached copies of letters sent to specified parties. Newspaper Advertisement: A copy of the proposed newspaper advertisement to be published in the Durango Herald is attached. La Plata d~1 Mine Page 2 CDMG Phase III Bond Release Application