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West Elk Mine <br />B Seam longwall experience indicates that some inflows continue past "one to two weeks," but <br />these inflows generally drop'to levels of less than 10 gpm, except as noted from the fault system <br />inflows. <br />9. CDMG staff quantified the maximum mining impact on the North Fork and the probable mining <br />impact on the North Fork for total dissolved solids (TDS), using conservative assumptions. The <br />conclusions reached from this analysis were: <br />"The worst case impact with regards to TDS in the North Fork during the irrigation <br />season would be to raise the TDS level from 130 to 189 mg/L. This is understandable <br />since the total discharge from all the mines, as used in the calculation, is only 7 percent <br />of the flow of the North Fork." <br />• "With the maximum, worst-case impact for TDS being only 189 mg/L, there is no need <br />to calculate the more realistic impact." (p. 16) <br />WWE has reviewed the cited TDS computations. The methodology is reasonable and provides <br />a conservative projection of what could occur in the area. This analysis can be translated to the <br />South of Divide permit revision area. As discussed in Surface Water Quality Effects, WWE has <br />revisited the TDS loading analysis conducted by CDMG and found that, even under the extreme <br />conditions of 1996 and early 1997, when MCC was forced to discharge large quantities of mine <br />water without adequate treatment (in response to large inflows from the BEM and 14HG fault <br />inflows), TDS levels in the North Fork were well below those considered to be a concern. <br />10. "Mine inflows are not normally significant when ephemeral or intermittent streams are <br />undermined. Mine inflows are seldomly, if ever, correlated to the undermining of <br />ephemeral or intermittent streams. Most of the streams to be undermined in the SOD <br />permit area are ephemeral and intermittent. Flow in these streams is concentrated in <br />periods of snowmelt and high intensity precipitation events. The stream gradients are steep and <br />their channels contain little alluvium." (p. 20). <br />In both the current permit and South of Divide mining area, many of the streams are ephemeral, <br />except a portion of the Deep Creek channel in Section 35 and the previously described transbasin <br />diversion of Dry Fork. Their steepness is characterized in Exhibit 55 and 55A, which contrasts <br />pre- and post -mining sediment transport. As described in the section Groundwater Quantity Effects, <br />neither the BEM Fault nor the 14HG Fault inflows are directly linked to surface inflows. <br />The experience of other mines in the area is useful in assessing possible ground water conditions in <br />the B and E-Searn. The Rear Mine No. 3 C -Seam workings are particularly relevant (see Map 5). <br />During previous inspections of this mine, no noticeable flowing areas within the mine V ere <br />observed. Mine operators reported inflows of less than 20 Ppm in 1995 to the Bear No. 3 B -Seam <br />workings (see section entitled Grounchvater Quantity Effects). Similar to the Mountain Coal <br />Company F -Seam experience, occasional roof drippers have been observed. Seasonal inflows in the <br />portal areas have been observed, similar to Mountain Coal Company's experience in the F -Seam. <br />Water has been observed in a pressurized state discharging from fractures just below landslide <br />debris in the portal of the Bear mine in 1986 during a period of high rainfall in the spring season. <br />2.05-183 Revised June 200.1 PRIO, January 2006, March2006; Rev. A1ay 2006 PRIG, A'ov. 2006 TRI07;Sep. 2007 PR12;Feb 2008 PR12 <br />