REP25820 - Laserfiche WebLink

Home Browse Search

• • • Hybologic Dara Interpretation and /inpacf Asretnnrnr for the Prnnif mid rt djarenr rlrcar Lively dry with only limited wet roof areas. Areas previously mapped as wet or damp are shown on Exhibit II. The wet areas of the 1st West Submain were thought to be associated with sandstone channels which immediately or closely overlie the coal seam and with fracture zones in the Lone Pine Gulch area. Panel 1 W1 S at 3 to 5 gpm. The flow increased to 5.5 gpm and 9.8 gpm during the 1st and 2nd quarters of 1988, respectively. Since this time. the Ilow declined steadily, to 1.2 gpm during the 3rd quarter of 1988 and to an unmcasurablc amount by the end of 1988. During 1989 the arcs outside the panel seals dried up completely. The area remained dry throughout 1990 as well. Panel-1 W3S Monitoring of well 38-H-1 during the 1990 water year indicates well water levels were still at pre- mining Icvcls. The water level in this well dropped about 100 feet from January to July 1987 while retreat mining was occurring (November 1986 to March 1987). We1138-H-1 is screened at three 20- foot intervals midway between the surface and the "F' seam coal. The "F" scam depth of cover is about 1000 Ceet at the 38-H-1 well location and averages about 900 feet over this panel. The total depth of well 38-H-I is 580 feet. No water was observed in the mine during devel- opment or retreat mining. Water observed in adjacent areas was thought to be coming from panel I W2S because it did not appear until retreat mining occurred in panel 1W2S. During 1990, water Icvcls in well 38-H-1 remained near pre- mining levels. Thus, data from well 38-H-1 indi- cate groundwater in the barren member above the rubble zone will not suffer long-term impacts from secondary mining. Wells 38-H-2 and 38-H-3 provided little useful information (see hydrographs in Appendix 1). Subsidence apparently damaged the casings of both wells and connected them with the mine ventila- tion system. In well 38-1{-2 the casing was ob- structed at 415 feel below the surface. Panel 1 W2S Retreat mining of panel 1 W25 was completed in November, 1937. Very little water wascncountcred in this panel during development or retreat. How- cvcr, flow from panel 1 W2S appeared on the Ooor of the 1st West Submain near the 1W2S seals shortly after secondary mining was completed. During the 4th quarter of 1987 flow was estimated Development mining in panel 1W3S began in March, 1987. Wet and damp roof areas were encountered from approximately 11 crosscut to 24 crosscut. These wet areas (roof drippers) produced very little flow but were fairly extensive over a wide area. Some were associated with a badly fractured immediate mint roof (overburden averages about 700 feet). The water is probably associated with sandstone channels directly above the coal seam and with Lone Pine Gulch features. Retreat mining was completed during September 1988. To date, no evidence of water is visible near the panel seals or in adjacent areas. Panel 1 W4S Developmem mining began in panel 1 W4S during October 1987. The "F" scam depth of cover aver- ages about 5110 feet over this panel. Roof drippers and wet areas were encountered in too( fractures and near the sandstone channel margins. The wet areas were not as large as those presen[ in panel 1W3S and did not produce any measurable (lows. No significant flows were encountered during retreat mining in 1989. No in-mine (lows were observed during 1990. Panel 1 W5S Development and retreat mining of this panel occurred during 1989. The overburden continues to thin to the west; depth of cover averages about 400 feet over panel 1 W5S (ranging from <200 feet to 750 feet at the southern panel end). Coal height also thins to the west. Mining conditions were similar to those in panel I W4S. Roof drippers and wet areas occurred, but no significant inflows were encountered. 9