Laserfiche WebLink
- r <br />• <br />FIELD IMPLEMENTATION AND REVIEW <br />DOE recently completed reclamation activities on the first phase of abandoned mines to be <br />reclaimed by this process. These activities include work at multiple shallow subsurface mine <br />sites (less than 30 meters below ground surface) and shallow surface mine sites (less than 6 <br />meters deep) on four lease tracts located in southwestern Colorado neaz the communities of Slick <br />Rock (C-SR-14A, C-SR-16, and C-SR-16A) and Uravan (C-CM-24). <br />The lease tracts are accessed by Colorado State Highway 141 and several county roads. The <br />regional topography consists of relatively flat-lying mesas that are broken up by the canyon <br />features of the Dolores and ~'~an Miguel Rivers and their respective tributaries. The region is <br />primarily vegetated with startds of pinyon pine and Utah juniper intermixed with open grass- and <br />sagebrush-covered pazks. The region has an and climate with an annual precipitation of 30 to 40 <br />centimeters. The primary land use in the lease-tract aeeas historically has been mining and <br />grazing, although some dryland agricultural crops are grown adjacent to Lease Tracts C-SR-16 <br />and C-SR-16A. Hunting is tl~e only recreational use of these lands. The mine sites within the <br />lease tracts aze located at elevations between 1,700 and 2,200 meters above mean sea level. The <br />uranium-bearing formation of interest in the region is the Salt Wash Member of the Morrison <br />Formation. By the very nature of the geologic, hydrologic, and climatic conditions of the region, <br />none of the mines associated with these lease tracts encountered groundwater; consequently, <br />groundwater was not an issue in the reclamation of these mine sites. <br />The mine sites on Lease "tracts C-SR-14A and C-SR-16A were all similaz because the ore <br />horizon or zone of mineralization was shallow, if not exposed at the surface, and was first <br />accessed by open pits. This near-surface occurrence of ore led to extensive surface workings. <br />Later, as the ore-bearing formation dipped further below grade, adits leading from the bottom of <br />the open pits were used to mine the ore. The overburden material and associated mine waste were <br />scattered throughout the different mine sites-some in lazge dumps, others in small piles from <br />single ore carts. The permanent closure of these mines and the subsequent recontouring activities <br />were achieved with conventional construction equipment (front-end loaders, backhoes, and <br />bulldozers). Mine sites with tuderground workings were left slightly mounded to prevent storm <br />water from eroding into the underground workings. The shallow open pit areas were left slightly <br />bowled to contain and control storm water. <br />Several of the mine sites on Lease Tract C-SR-16 were also similaz because the ore horizon <br />or zone of mineralization at each site was entirely below grade and was accessed by shallow, <br />gently sloping inclines. These mine sites had mine-specific waste dumps. Two of the mine sites <br />were somewhat unique because they had ventilation shafts. The permanent closure of these <br />mines (including the ventilati~~n shafts) and the subsequent recontouring activities were achieved <br />relatively simply with conventional construction equipment. These mine sites were left slightly <br />mounded to prevent storm water from eroding into the underground workings. <br />One mine site on Lease Tract C-SR-16 was distinctly unique from all of the other mine sites <br />because it is located along and under the rim of Sttmmit Canyon. This mine site consisted of <br />eight adits located approximately 8 meters below the canyon rim. During past mining operations, <br />the mine waste materials were deposited along the outer edge of the mine-site access road that <br />traversed along the south slope of the canyon to the different mine adits. The large boulders <br />found above and adjacent to the mine portals along the canyon rim were considered to be <br />extremely unstable, and workE:r safety became the primary concern during the reclamation of this <br />site. These unstable condition:; prompted the use of explosives to close the portals. Vertical holes <br />were drilled along the rim above the portals, and angle holes were drilled into the adit walls from <br />an area directly in front of the respective adits. The holes were then loaded with explosives and <br />detonated. This method was successful at seven of the eight adits. However, the operation had to <br />1278-tab.doc <br />