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-25- natural runoff from the surface facilities area. All runoff from the surface facilities will be channeled into sediment ponds. These sediment ponds will be designed for total containment of the ten year-24 hour storm. All excess runoff will be recycled into the hydraulic mining process. Accumulated sediment will be removed as necessary to ensure that the pond provides adequate storage at all times. A coarse refuse embankment will be constructed in a small ephemeral drainage tributary to the Colorado River, The embankment will be underlain by the relatively impermeable Mancos Shale. The embankment will be formed of coarse refuse generated during the mining process and will impound the slurry refuse generated through the hydraulic mining process. The embankment will be designed to impound approximately 16,000,000 tons of refuse over an expected project life of 25 years. The embankment will be built in a phased process where the embankment is always of sufficient height to hold the slurry and refuse from .the mining process and to totally contain the probable maximum precipitation of the drainage area above the embankment. A sediment pond will be built downstream of the embankment, and will contain any runoff from the face of the refuse embankment occurring from storm events. This pond is designed to totally contain the 10 year-24 hour runoff event. This pond also serves a second function. Although the Mancos shale is relatively impermeable, a ground water investigation has shown that some element of ground water movement is present through the Mancos. A preliminary analysis by a consultant for the applicant indicates that seepage from the coal refuse impoundment will be about 50 to 60 9pm. This seepage is expected to surface in the channel downstream from the main coal refuse embankment. Pond B will be constructed to collect any seepage which may surface in the ephemeral channel. This seepage will be reused in the hydraulic mining process. There is the potential for some seepage from the embankment reaching the alluvial valley floor just downstream from the embankment by short-circuiting around the sediment pond. The applicant has committed to continue monitoring ground water wells placed in the alluvium in order to detect any change in alluvial water quality that might occur. In summary, the Coal Ridge No. 1 Mine has been designed for containment and reuse of all water generated from the mining process and by surface runoff. The potential impacts to quality of the Colorado River due to mining at Coal Ridge No. 1 are isolated to increased suspended sediment yield from outslopes of the railroad and access roads. The outs]opes wil] be revegetated once construction is complete, so this impact will be short term. The alluvium present in the vicinity of the Coal Ridge No. 1 Mine and adjacent to the Colorado River is recharged by the Colorado River surface water and by surface runoff from the upland area. The subcrop of the Wheeler seam is located approximately 55 feet above the alluvium and dips steeply away from the alluvial body. Undermining of the alluvial body will not occur during the life-of-mine. Therefore, dewatering of the Wheeler seam due to mining is not expected to impact the alluvium or surface water system of the Colorado River.