GENERAL49492 - Laserfiche WebLink

Home Browse Search

dilution within the aquifers and increase the distance a detectable mine water plume would spread. The degradation of water quality in the co8i aquifers would not impact ground water use in the general area, since the poor quality and depth of the prior existing water limited use originally. The amount of depletion of flow in the Purgatoire River alluvial aquifer has been estimated to be 5 gpm for the New Elk Mine, and 2.3 gpm for the Golden Eagle Mine. The combined depletion of the stream/alluvial system is 7.3 gpm, which amounts to 0.3$ of the low flow in the Purgatoire River. This minor loss in flow is expected to be offset during mining by the discharge of treated mine waters from the underground mine workings. The current average discharge of water is 123 gpm from the New Elk Mine, and 30 gpm from the Golden Eagle Mine. Each mine is predicted to discharge approximately 180 gpm at full development. The cumulative effect of the total volume of discharges from the two mines is to increase the total dissolved solids concentrations by 76 mq/1 in the Purgatoire River at the Golden Eagle mine during periods of low water flowage. Added to baseline concentrations of 300 mg/1, or less, this increase would not limit the use of water for either flood irrigation, livestock watering, domestic or municipal uses downstream. D. Short-term Uses versus Long-term Productivity • Mining would not appreciably alter the surface topography or affect the overlying agricultural and grazing operations in the mine area. The proposed mining operations would not interrupt, discontinue, or preclude farming in the valley adjacent to the Purgatoire River. Other than the existing access roads, the existing sediment control, and the main water intake systems, no additional surface disturbance would occur bn the valley floor. Underground coal extraction is limited to 50$ beneath the valley floor to minimize subsidence effects. The proposed mining operations would not cause material damage to the quantity and the quality of surface and ground water that supply the valley floor. The proposed mining operations would preserve the essential hydrologic functions of the valley floor. Disapgzoval of the proposed action would not have an adverse impact on the environmental conditions which currently exist in the area proposed to be mined. E. Irreversible and Irretrievable Commitments of Resources Approval of the proposed action would result in the irretrievable loss of the coal resource due to the underground method of extraction. •' ~ 13