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• Hydrologic Dafa rntcyretanon mid Impact Asusmtent for Pmti~ Arco and Adjacent Arcar L J • Panel 1W5S Development mining of this panel began during January 1989. The overburden continues to thin to the west; depth of cover averages about 400 feet over panel 1W55 (ranging from <200 feet to 750 feet at the southern panel end). Coal height also thins to the west. Mining condi- tions should be similar to those in panel 1W4S. Although roof drippers and wet areas are an- ticipated to be associated with fractures and channels, no significant inflows are expected. Panel 1W6S Mining of this panel may or may not begin during 1989, depending upon market and other conditions. Panel 1W65 would be under an average of about 350 feet of overburden. Due to the trend of decreasing wver and thinning coal with westward expansion, this panel may be the last panel to the west driven o[[ the ls[ West Submain. Hydrologic conditions in this panel should be similar to the other panels off the ls[ West Submain. Thus, wet areas and roof drips associated with fractures and sandstone channels are expected. Fractures would likely be associated with the Lone Pine Gulch topography. 1st East Submain Plans for 1989 include retreat mining the 1st East Submain back to the 2 crosscut. Poor roof conditions (fractures, water, and weak rock mater- ial) are the major reasons [or retreat mining this Submain section. The poor roof conditions may also limit pillar extraction. Although increased Oows are anticipated as subsidence occurs, they are not expected to be significant. An alternative access Submain to coal in the eastern portion of Federal Lease C-1362 is planned. This Submain would be driven further to the south under higher overburden and further from the fracture zones associated with the branches of Sylvester Gulch. Water Quality Samples taken during 1988 indicate water quality in the mine to be good and should pose no problem for discharge. The ultimate discharges should readily meet NPDES effluent limitations after settling and there should be no measurable impact to receiving waters. Quality of water discharged in 1989 should be similar to the 1988 values shown in Table 4. GROUNDWATER Same groundwater wells exhibited slightly changed conditions in some instances and the subsidence monitoring deep wells showed some influence from mining. Generally, the wells re- mained fairly constant as compared to previous years. Most notably, the 1988 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 patterns. • Refuse area wells GP-3 through GP-5, as in previous years, contained no water. • Barren Member well 38-H-1, as previously described, was affected by subsidence. • Barren Member well 38-H-2 con- tinued to have casing blockage prob- lems which have occurred since it was installed. Very little data were col- lected a[ this well due to the prob- lem. The rasing was apparently dam- aged by subsidence as described ear- lier in this section. • Barren Member well 38-H-3 provided no use[ul well data in 1988. Moisture problems with [he casing and later communication with the mine work- ings, probably caused by subsidence, precluded the determination of water levels. 11