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Ms. Catherine Robertson <br />March 20, :?008 <br />Page 4 <br />flow regime and groundwater quality. Section 4.2.6 states that "once <br />gror~rndwater is encountered; the water will be collected and pumped from the <br />mine. " However, there is no mention of where the water will be discharged and <br />what potential impacts could result from mine water discharge to downstream <br />tributaries or shallow alluvial groundwater. <br />Based on our experience from the nearby McClane Canyon Mine the current <br />estimated mine inflow is 20 gallons per minute (gpm) and when water is not being <br />used in the mining process it is dischazged up to 150 gpm. The Red Cliff project <br />will be much larger in scale. If mining progresses quickly and wet coal is <br />encountered, then inflows and subsequent discharges could be significantly larger <br />than those encountered at McClane Canyon Mine. Therefore, the DRMS does not <br />agree with the statement on page 3.2-30 that "long term inflows are expected to be <br />lower (around 10 gpm) based on information from the McClane Canyon Mine in <br />200.5 when it was shut down. "The DRMS believes that the long term mine inflow <br />rate of 10 gpm may be underestimated and there is no information provided to <br />substantiate this estimate. There is also no discussion of the potential for mine <br />dischazge. <br />A description of how mine inflow water will be handled (consumptively used <br />by the mine or discharged to the surface) should be included in the PDEIS. <br />We recommend that in addition to the long term mine iunflow estimate; <br />provide a worse case scenario reflecting the maximum coal production rate <br />of 8,000,000 tons per year. Given the fact that water has been encountered in <br />the Cameo coal seam and if the worse case scenario of 8,000,000 tons of coal <br />per year are mined, then there will likely be much larger mine inflows. The <br />Affected Environment and Environmental Consequences sections of the <br />PD>•:IS should be revised to identify the potential impacts resulting from the <br />estimated maximum mine inflow rate and analysis of the potential for mine <br />water discharge. <br />6. In Appendix C Subsidence, it is clearly stated that Big Salt Wash is a perennial <br />stream that overlies planned Red Cliff Mine workings. The discussion of Big Salt <br />CreE;k Wash under Section 3.2.6 Surface Water should be clarified. On page 3.2- <br />25 the statement is made "According to the USGS map, Big Salt Creek Wash is a <br />losing stream. " The USGS indicates that the stream changes from perennial to <br />inter-mfttent just south of the Ruby Lee Reservoir. " <br />We recommend that this discussion under Section 3.2.6 be modified to <br />clearly explain that the portion of Big Salt Wash along its entire length <br />within the coal lease area and above the location of planned mine workings is <br />a perennial stream. <br />7. The DRMS does not consider the 200 foot minimum overburden depth sufficient <br />to protect surface water and ground water resources above the mined areas of the <br />Redcliff Mine. Given the planned mining height and the predicted subsidence, <br />