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• • Hydrologic Monitoring Acdvidu Appendix G. Hydrographs depicting water levels from 1978 to present have been included as Appendix H. Water level and sampling records for water year 1988 were complete for seven wells. Water in 10 wells was either nonexistent or insufficient for sampling at all during the 1988 water year (except [or well SW-3 where one sample was obtained). Samples were not acquired from wells SOM-38-H2 and SOM-38-H3 because the casings were damaged (probably by ]ocal subsidence). in addition, since the subsidence occurred, both wells have apparently been in contact with the mine ventilation system. These problems precluded sampling during the 1988 water year. MINE WATER MONITORING Mine inflows in areas being actively mined were mapped on an ongoing basis during water year 1988. Areas of previous mine inflows were monitored by occasional visits and by sampling of ^ow and quality during dewatering operations. Exhibit II shows locations of inflows and estimat- ed amounts of mine inflows as well as sampling locations. Areas of standing water were also mapped and are shown on Exhibit II. InOows into previously mined areas along Sylvester Gulch and near the main portals con- tinued to be highly responsive to the spring runoff season. Exhibit II shows estimated average flows for the spring runoff season and the low flow time of year, as well as hydrologic conditions encountered in areas mined during water year 1988. Inflows were slightly less than in 1987 for areas around Sylvester Gulch. Because of these reduced inflows, no water was discharged at the Sylvester Gulch Fan discharge point (NPDES point 011). However, the discharge from the mine portal areas was approximately the same as 1987. Areas along the Sylvester Gulch Main Mine Fan entries produced measured flows ranging from 0.5 to 1.5 gpm during low flow conditions and 5 [0 7 gpm during spring runoff conditions (see Exhibit II for the two locations of flow measurements). The old Sylvester Gulch area (entries 14 through 21, main intakes) produced estimated flows ranging from 0 gpm during low flow conditions to 1 gpm during spring runoff conditions. The main portal area (entries 1 through 5) had estimated flows ranging from 0 to 0.25 gpm during low flow conditions and 1 to 3 gpm during spring runoff conditions. Entry 1 on the east side of the main intake from crosscut 1 to crosscut 7 had standing water year-round. Flows in this area were estimated at 0.0 to 0.5 gpm during low flow conditions and 2 to 5 gpm during the spring runoff. Entry 9 on the west side of the southwest main intakes From portal entry 5 to crosscut 7 produced flows estimated at 0 to 0.25 gpm during low flow conditions and 0.5 to 1.0 gpm during spring runoff conditions. The flow from panel 1W2S that appeared near the seals during November and December 1987 increased to a peak of approximately 9.8 gpm during the 2nd quarter of 1988. However, since this peak, the Oow has steadily declined. By the end of 1988, no measurable flow existed, although standing water was still present in the sump near the 1W2S seals. Although Oows in the 1 East Submains remained essentially the same as in 1987 (1 gpm during low flow and 3 gpm during spring runoff), the 1 West Submains were generally drier in 1988. In particular, the areas of wet roof between crosscuts 27 and 33 dried up during the 1988 water year. However, these areas never produced sustained flows. The wet conditions in the 1st East Submain can be attributed to sandstone channels, the Sylvester Gulch stream zone, and low cover. New areas mined in 1988 produced only wet areas with no measurable Oows. These wet areas consisted of roof drippers, wet ribs and damp floors in Panel 1W4S. These areas were encoun- tered in roof fractures and near the sandstone channel margins. 5