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Scaiaz - 2.04.7 <br />seattts, the following hydraulic characteristics have been estimated bazed on typical values presented in <br />Applied Hydrogeology (Fedder, 1988): <br />• Transmtsstvity- 0.90 to 0.96 <br />• Porosity- 0.0012 <br />• Aquifer Thickness - 2 to 14 feet <br />I-L.storic mining operations have encountered perched ground water, with resulting mine inflows, <br />from the E, D, ~ and B coal seams or the associated overlying or underlying uniss. Continued <br />mining operations are expetted to encounter perched ground water from the B seam (Sanborn Creek <br />Mute) and D seam (Elk Creek Mute) sequences. Recopied mine inflows to the Somerset NLne <br />workings (B seam) were approximately 235 gpm and inflow rates were relatively cotuistent with no <br />significant increase in discharge from caved areas following completion of pillar recovery and <br />subsequent roof collapse. Inflows to the active Sanborn Creek IvLne (B and C seams) average 100 <br />gpm, although interception of a fracture system resulted in a short-term increase in peak inflows to <br />approximately 250 gpm and inflow potential has been calculated co be az high as 400 gpm The <br />Oliver Mute was developed in the D seam, with most of the development upgradient from iss <br />outcrop/sub-crop with Elk Geek Available information indicates that the Oliver Mute workings <br />were generallydrywith isolated areaz of limited mine inflow (0 to 6 gpm). <br />The majority of the exploration drillholes completed in the mine area have been relatively dry, with <br />occasional damp zones encountered in some of the holes and limited occurrences of actual flowing <br />ground water. Drillholes SG 1, 2, and 3 were drilled in the vicinity of the Sanborn Geek NLne. <br />Dtillhole SG1 was essentially dryexcept for a damp zone at a depth of approximately 40 feet until it <br />intercepted the Rollins sandstone. Dtillholes SG2 and SG3 encountered ground water in both the D <br />Coal Seam and Rollins sandstone. Mute inflow potential from the D seam below its outcrop/sub- <br />crop with Ells Geek is un-quantified at this tithe but drilling results indicate tltac the seam does <br />contain water in the vicinity of Elk Creek Inflow potential for the D, C, and B coal seattu tray be <br />estimated acing the following relationship that is based on Darcy~s Law: <br />Q = ((VU)('I)(Ii)/(n)(L)) where; <br />Q is steady-state flow rate (gpd) based on the total length of exposed coal face <br />W is the width (fr) of mine workings adjacent to the outcrop <br />T is transmissivity (gpd/fr) <br />H u potentiometric head (ft) of potential recharge source above mining (Ells Creek <br />above D seam and outcroplsubcrop above C and B seams} <br />n is coal seam porosity <br />L is distance (fr) from mine workings to outcrop <br />The results of this calculation for the respective coal seams or azsociated clastic sequences are az <br />follow: <br />Coal Seam ~) T ft H ft n L ft d/ m <br />D 6,600 2.00 100 0.0012 2,400 458,330/318 <br />C 17,495 0.90 200 0.0012 7,380 355,680/247 <br />B 16,050 0.96 250 0.0012 12,074 265,860/ 185 <br />Based on recorded mine inflows, the mine inflow estimates above are relatively accurate and can be <br />used az a general indicator of anticipated inflow rates. <br />• In most cases, the volume and rate of any perched ground water discharge at stratigraphic outcrops is <br />limited. Because most of the perched ground water occurs in near-surface units, discharge is <br />frequently ephemeral, flowing Eor a brief period following spring snowmelt until infiltration from <br />PR04 2.04-26 Revised August 2000 <br />