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<br />• <br />~~ <br />2.0 Nydro(ogic Data /nrerprcranon and <br />mining activities until the extraction of coal <br />breaches the well, such as demonstrated th <br />Well SOM-C-72-H. <br />Water migration in the coal seam, and in the <br />underlying and overlying formation, is very <br />low; the boundary formations are relatively <br />impermeable. The coal seam carries little <br />water due to low quantities of water <br />available for recharge. In summary, there is <br />a low impact on the water regime of the <br />mined and adjacent areas. <br />2.2 ASSESSMENT OF <br />SPRINGS <br />MCC monitored twenty-six springs during <br />WY 1994. Baseline monitoring in the <br />Jumbo Mountain tract added seventeen sites <br />to the previous program. May flows at all <br />springs totalled 200.63 gpm (0.45 cfs). <br />Five sites with flows greater than 15 gpm <br />contributed 135.71 gpm or sixty-three <br />percent of the total flow. These sites were <br />G-22, G-24, G-33 and jumbo Mountain sites <br />15 and 17. <br />Ten of the twenty-six springs monitored <br />have a relatively constant flow while sixteen <br />springs show definite seasonal variation. <br />With the exception of Springs G-12 and G- <br />20, springs are consistently responsive to <br />spring runoff. The flow rates of springs G- <br />12 and G-20 are sporadic and many times <br />do not correlate well with other seasonal <br />parameters such as snowpack, precipitation, <br />or streamflow. A comparison of WY 1994 <br />monitoring data with previous years shows <br />no significant trends or changes which can <br />be associated with mining activity. <br />Monitoring within the Jumbo Mountain tract <br />included two decreed springs: !/22 (Jumbo <br />Mountain site 15) and J123 (Jumbo Mountain <br />site 18). Site CR-12 had no Flow in WY <br />1994. <br />RI ?101IOA/OS/OS/95(8:04am) <br />Assersmern for the Permir and Adjarenr Areas <br />Six springs had one or more water quality <br />parameters outside baseline ranges. This <br />reflects the limited duration of baseline <br />spring monitoring rather than any impact <br />from mining. <br />There appears to be no impact from mining <br />activities on springs. None would be <br />expected if the mine workings are not hy- <br />draulically connected. Ground subsidence <br />(transmission of crack up through the over- <br />burden or settlement) has apparently not <br />adversely impacted the integrity of the <br />shallow groundwater systems. <br />2.3 ASSESSMENT OF <br />GROUNDWATER <br />Wells remained fairly constant compared to <br />previous years. However, two wells located <br />south of mining, SOM-2-H and SOM-23-H- <br />2, exhibited water level changes. SOM-C- <br />72-H was undermined. <br />2.3.1 Alluvial Wells and <br />the Lower Refuse <br />Pile <br />In 1994, MCC produced 53,886 tons of <br />reject material. Currently there is a total of <br />836,868 tons of material in the Lower <br />Refuse Pile. <br />Data suggests that no potentiometric surface <br />has developed in the refuse pile fill as GP-3, <br />GP-4, and GP-5 are still dry. This may be <br />due to the low vertical permeability of the <br />refuse pile materials and the small quantity <br />of water available for rechazge due to <br />effective surface water drainage from the <br />pile. <br />General relationships of WY 1994 data with <br />baseline limits for well SG-1 is summarized <br />in Appendix H. Samples from well SG-1 <br />were within the range of baseline parameters <br />19 <br />