Laserfiche WebLink
West Elk Mine <br />. intercepted by a permeable formation or natural fractures exposed by stream erosion) should only <br />concern the current owner of the water right. <br />Methane Concentrations in the Oliver No. 2 Portal Area <br />Methane was also encountered in the portal area of the Oliver No. 2 Mine during exploration <br />drilling for the State Highway 133 roadbed. Boyd Emmons, State Coal Mine Inspector, stopped <br />drilling in one hole north of the Oliver No. 2 portal when 100 percent methane was detected. It was <br />14 to 15 days before CDOT could remove steel from one hole (Boyd Emmons, Oral <br />Communication, November 6, 1996). According to Emmons, methane still is likely to be present in <br />the roadbed. <br />Water and Methane Potential in the B-Seam-Oliver No. 2 Mine Area <br />Based on the history of mining the Oliver No. 2, water and methane also may locally be expected to <br />be encountered during the mining of the B Seam in that area at least. Apparently most of the water <br />and methane encountered in the Oliver No. 2 Mine was present in fractures, joints, bedding planes, <br />or in permeable rocks near the coal seam mined. However, with about 250 feet of shale, siltstone, <br />and sandstone between the B Seam and the E/DO Seam, the extent and volume of water and <br />methane cannot be predicted without drilling. <br />One drill hole located near the mouth of the unnamed drainage west of Box Canyon, near the <br />haulageway of the Oliver No. 2 Mine, was observed to exhaust gas and water vapor in a volume of <br />5 to 10 cubic feet per minute (5-10 cfin) at atmospheric pressure during field studies in October <br />1996. The shut-off pressure was estimated to be 20 psi. The source of the methane and water vapor <br />was reported to be mainly from the A and B Seams. This would indicate that water and methane <br />may be encountered during mining of the B Seam in the Oliver No. 2 Mine area. Potential Impact <br />of Water on Subsidence in Wet Mining Areas <br />As discussed in a previous section, Geologic Factors Influencing Subsidence (2.05.6 (6) (e) (i) (B)), <br />the moisture content of the caved and downwarped rocks controls the amount of subsidence that can <br />be expected. In mining areas where water might be encountered in an area equal to, or greater than, <br />the width of the proposed longwall panels, maximum vertical displacement may be expected to <br />approach 0.8 times the coal-extraction thickness. Based on available information, the E Seam <br />overburden in the South of Divide mining area is not expected to contain significant volumes of <br />water within the strata. No water was encountered in shafts 1, 2, and 3 in E Seam or layers above <br />the E Seam. No water has been encountered during E Seam development. No water has been <br />encountered in drilling the Methane Drainage Wells through E Seam which are north of and down- <br />dip from the South of Divide Area. However, because water has been identified in E Seam <br />monitoring wells in the SOD area, water may be encountered as a result of E Seam mining. <br />The water in the E Seam swells is described at 2.04 Grounaha,ater Oualitv and Characteristics of tine <br />E Sean? Monitoring f'ells and Table 7. A summary of water characteristics of groundwater that <br />could be encountered is found in Exhibit 71 Appendix G which details the quantity and quality <br />anticipated to be encountered. Basically, the water quality of the E Seam waters are similar to the B <br />Seam waters. For instance, wells in SOM 3E and SOM 23-H-2 exhibit sodium bicarbonate type <br />water with a slightly alkaline PH, (8.2 to 8.4) moderately high TDS (1330 to 1,540 mg/L). <br />2.05-143 Revised Jm7e 2003 PRIG. Rev. AfarcI72006; May 2006 PRIG, Nov. 2006TR107,Apri12007TR108;Sep. 2007 PR12; Feb. 2008 PR-12