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A4ounlain Coal Comparry J997 Annual Hydrology Report {f'esi E/k Mine <br />inflows were observed to be as high as 250 gpm at Cross-cut #3 of Entry #1 with subsequent <br />• decreases occurring within 7 days to 140 gpm. <br />A second fault system, with a similaz northeasterly trend, was encountered on January 20, 1997 <br />neaz Cross-cut #11 of Entry No. 2 of 14 Southeast Headgate (a.k.a. 1SE Headgate). This fault <br />system was subsequently named for its location (i.e., 14SE Headgate fault). Initial inflows at <br />this location were estimated to be approximately 8,000 gpm. Within a months time these inflows <br />had decreased to approximately 1,750 gpm. By July of 1997 inflows at this location had <br />decreased to 150-200 gpm where they have remained constant throughout WY97. The location <br />of these mining areas and the associated mine inflows aze shown on Map 1. <br />Aside from the fault system inflows, known azeas of historic inflows due to low overburden and <br />proximity to outcrops were once again observed. Groundwater inflows, excluding the B East <br />Mains and 14 SE Headgate faults contributions, initially ranged from 1 to 5 gpm and later dried <br />up, with the exception of the inflow in the ]0 NETG. This flow began at 80 gpm and later <br />dropped to approximately 35 gpm. Total inflows from the B East Mains and 14 SE Headgate <br />faults during WY97 were estimated to be 161 and 504 acre-feet, respectively. <br />Longwall Mining <br />Longwall mining operations during WY97 were concentrated in the western portion of the mine <br />property (Map 1). Specifically, this included the remaining one-quarter of the 8NW longwall <br />panel (Jumbo Mountain north) and all of the 9NW longwall panel (Jumbo Mountain south). The <br />. 9NW longwall panel was completed in August of 1997. The longwall was moved to the IONE <br />longwall panel where it started production in September. Only about one-eighth of the IONE <br />longwall panel was mined in WY97. <br />Observed mine inflows were nearly non-existent in the 8NW and 9NW longwall panels. While <br />not completely unexpected, mining conditions were drier than previously experienced while <br />mining the other Northwest Panels. Mine inflows in the l ONE longwall panel were nonexistent <br />except as noted in development mining (see below). <br />Development Mining <br />Development mining utilizes room-and-pillaz mining methods to create tailgates, headgates and <br />bleeder entries azound the longwall panels for utilities, safety equipment, conveyors, ventilation <br />and access routes. As a result, development mining is usually done in azeas of the mine where <br />limited information is known about potential water-bearing features such as faults and fractures, <br />unless encountered in exploratory drilling from the surface. It is from these areas that the <br />groundwater inflows were noted. <br />Specifically, wet areas, seeps and/or drippers were noted from the floor in the 9 Northwest <br />headgate at Cross-cut #31, from the roof in the 12 Northwest headgate at Cross-cuts #] 0, 12, 19, <br />20 and 42, from the roof in the 1 i Northeast tailgate near cross cuts #5, 7 and 9, from the roof in <br />11 Northeast headgate at Cross-cut #18, from the roof and rib in the 10 Northeast tailgate at <br />Cross-cut #20 and from the roof and floor at multiple locations along the B East Mains and 14 <br />. SEHG fault projections in the Box Canyon Mains and longwall panels (see Map 1). All of the <br />31-032.4 0 Page rig r Water ngineers <br />