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1 Hole 2-7M is apparently more sensitive to room-and-pillar mining. The water level in this hole has been dropping since mid-1987 when room-and-pillar mining approached to within about 700 feet. This area was mined past in June 1988 and the water level has continued to drop, although no monitor holes were intercepted underground. In April 1990, LW3 was mined past this location. ' The March 1990 water level had dropped beyond our measurement capability and remained so during this monitoring period. Longwall panel 4 was mined past this location in August 1991. ' The hydrographs of the °lower sandstone facies" are designated by the letter 'L' following the hole number. The original hole 2-17L was plugged in early fall 1985 as it was feared the mine would intercept it. As it fumed out, the hole was never encountered in the workings. As required by CMLRD, a new hole was drilled and completed in the "lower sandstone facies". From the time the new hole was completed, the water levels in this hole have fallen. During May 1986, mining t in gate road 2nd East intercepted an exploration hole, (21012-9) that had been drilled in 1978. This hole had been plugged with heavy mud but leaked from both the mine roof and floor when ' the hole was intercepted. Water flow from the hole in the roof was about 3 gpm (gallons per minute) and was plugged with a packer. The flow from the hole in the floor was on the order of 1 gpm and was plugged by pumping an expanding grout into the hole. This exploration hole is located about 1500 feet from 2-17L and the leak in the floor may have reduced the piezometric pressure in the °lower sandstone facies' at 2-17L. During March of 1987, another exploration ' hole (21012-10) was intercepted by mining in gate road 3rd East. This hole also leaked at about the same rate from roof and floor. The hole in the roof was plugged with expanding foam grout. The hole in the floor was plugged with Portland Cement pumped down a one inch line to about 100 feet. The leaks in both 21012-9 and 21012-10 are probably responsible for the fall in water levels detected at 2-17L during the fourth water year. Mining of LW-1 approached to within 500 feet of this hole in February 1988. During this monitoring period, the water level remained beyond the capability of the monitoring equipment (deeper than 300 feet). Perhaps the combination of ' leaking exploration holes and floor cracking as coal was removed by the longwall have reduced the piezometric pressure enough to drop the water level below 300 feet. Monitoring of this hole will continue to see 'rf it recovers. Monitor holes 2-7L and TW2-7L are on the same location and apparently also responded to the ' two leaking exploration holes. Longwall panel 3 was mined past this location in April 1990 and the water level has since dropped below 300 feet. Longwall panel 4 was mined past this location in August 1991. The water level in these two holes remained below 300 feet during this ' monitoring period. ' 10 1