GENERAL35449 - Laserfiche WebLink

Home Browse Search

-26- Hydraulic mining requires large quantities of water for operations such as cutting of the coal and, in the slurry line, transporting fine refuse to the waste site. The operation has facilities designed to process and recirculate the majority of water required for the operation. The water circulation is designed as a closed-system, with the major water loss occurring through evaporation, adhesion to the coal and refuse, and by seepage underground during mining. The application projects that water loss through these processes will require a makeup of approximately 600 acre feet of water annually to the system. The Coai Ridge No. 1 Mine has acquired water rights more than sufficient to augment their annual projected water loss. The major water rights owned by the applicant are from the Vulcan Ditch, which originates in Canyon Creek, a tributary to the Colorado River on the north side of the River. The water from this ditch is siphoned underneath the Colorado River and has been historically used to flood irrigate the alluvial valley floor north and east of the surface facilities. During low-flow periods, the applicant has committed to giving priority to irrigation of the historic alluvial valley floor. There does exist the possibility that use of valid water rights by the applicant will detrimentally impact the quantity of water available to the Colorado River. The use of 600 acre-fett annually equals an average flow of 0.83 cfs. This reduction of the average 1983 flow of 4,969 cfs in the Colorado River is an insignificant impact. In conclusion, no significant impacts to the hydrologic balance are projected for the life-of-mine operation at the Coal Ridge No. 1 facilities. Cummulative Hydrologic Impacts The probable hyrdologic consequences of mining within the vicinity of the Eastside Mine were previously documented in Section VIII. The impacts were only carried as far as the Harvey Gap drainage and alluvium directly in contact with Harvey Gap. In order to address impacts to the Colorado River Basin, a summary of the probable impacts of the Eastside Mine is required. The worst case impact to the surface water system of Harvey Gap due to mining activities at Eastside was projected to occur during the non-irrigation season. The low-flow of Harvey Gap, occurring due to seeps along the base of an irrigation embankment was 0.5 cfs. A worst case release of water from the mine site showed an increase in the level of TDS from 755 mg/1 to 1054 mg/1 downstream of the mine site. The low-flow on record for the Colorado River at Glenwood Springs is 870 cfs. The mean level of TDS present in the Colorado River during the 83 water year was 427 mg/l. Loading of the worst case level of TDS in Harvey Gap into the low-flow of the Colorado River gives a rise in TDS of 0.5 mg/l. This rise is insignificant and would not affect the quality of the stream. No other significant impacts to the hydrologic balance were predicted due to mining at the Eastside operation. In conclusion, based on information currently available, mining at the Eastside and Coal Ridge No. 1 operations is not projected to cummulatively impact the quality or quantity of ground water or surface water within the Colorado Basin.