2001-12-11_REPORT - C1980007 - Laserfiche WebLink

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• • C~ Hydrologic Da(a Interpretation and Impact Atsccm(enf for Pmni( Arca and Adfacm(Arear West Submain adjacent to the panel. However, pumping was unnecessary. Panel 1W6S Mining of this panel began during 1989. Panel 1W6S is under an average of about 350 feet of overburden. Due to the trend of decreasing cover and thinning coal with westward expansion, this panel may be the last panel to the west driven off the 1st West Submain. Hydrologic conditions in this panel are similar to the other panels off the 1st West Submain. The panel is mostly dry. A few very small localized damp roof areas or roof drips have occurred. 1st East Submain "B" Seam Slopes Development of the "B"seam slopes is expected to start during the second quarter of 1990. Water may be encountered during this development. However, Bows are expected to be minimal. If pumping is required, the water will be delivered to pond MB-1. Water Quality Samples taken during 1989 indicate water quality in the mine to be good. Accordingly, it should pose no problem for discharge. The discharges should readily meet NPDES effluent limitations after settling and should not measurably impact receiv- ing waters. Quality of water discharged in 1990 should be similar to the 1989 values shown in Table 5. The 1st East Submains were retreat mined and sealed during the first half of 1989. Poor roof conditions (fractures, water, and weak rock mater- ial) were the major reasons far retreat mining this submain section. Although increased (lows may occur following subsidence, they are not expected to be significant. No flows have developed to date. An alternative access submain to coal in the eastern portion of Federal Lease C-1362 is planned. Placement of this submain would be further to the south under higher overburden and further from the fracture zones associated with the branches of Sylvester Gulch. Due to plans to access the "B" scam, this submain is unlikely to be driven for several years. Northwest Submains and Associated Panels The opening of the Northwest Submains and three associated panels is planned for 1990. The Sub- mains would strike out from the Southwest Main Intakes (Exhibit ili). Some water is expected be- cause colluvium is located above this area. Also, cover over the panels is low to moderate. However, no significant Bows or hydrologic impacts are anticipated. Groundwater Some groundwater wells exhibited slightly changed conditions in some instances and the subsidence monitoring deep wells showed some influence from mining. Overall, the wells remained fairly constant compared to previous years. Most notably, the 1989 data indicate: • Refuse area wells SG-1 and GP-1 continued to show lower levels than in years previous to 1987. This is due to persistent lower precipitation pat- terns. • Refuse area wells GP-3 through GP-5, as in previous years, contained no water. • Barren Member well 38-H-1, as previ- ously described, was affected by subsi- dence. This well has since recovered to pre-mining water levels. • Barren Member well 38-H-2 contin- ued to have casing blockage problems which occurred after it was installed. Very little data were collected at this well due to the problem. The 10