2008-06-09_REVISION - C1980007 (3)

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Water '~ drainage bottoms. Temporary direct effects from drilling could include: Modification of the water table surface until equilibrium conditions are --. reestablished, and • • Degradation of groundwater quality due interaction with drilling fluids. These direct effects are not expected and would be substantially mitigated by design criteria. Furthermore the duration of these temporal affects is expected to be on the order of days or months, with no foreseeable long-tern degradation. If substantial quantities of ground water were encountered in any borehole, high- density additives would be introduced with the circulation media to contain the water flows, and casing would be extended and cemented in place to case off the flow source. Based on MCC coal methane drainage experience on panels 16-24, drilling circulation media could include air, water, and biodegradable polymer foam. Gels, surfactants, and other bentonite- based drilling muds could also be used to stabilize the drillhole, if necessary. Other materials, including crushed peanut shells, cottonseed hulls and cedar fiber could also be added to the circulation medium to help stabilization. All drilling fluids and additive that could be used are either naturally occurring inorganic or organic materials or biodegradable compounds (USDA FS 2002a). Water quality in the shallow perched groundwater systems has been characterized as similar to surface water quality, such that substantial changes in geochemistry due to mixing from two distinct shallow perched zones or from ground water/surface water mixing would not be expected. Boreholes would be stabilized using the same methods as drill holes during drilling, where necessary. These materials and other borehole stabilizing additives would maintain pressure in the borehole adequate to prevent substantial ground water inflow (and mixing) in borehole where ground water is encountered. Because all. drilling fluids and stabilization additives would be biodegradable materials, any changes in ground water quality from drilling operations would be temporary. Based on spring and seep survey locations, several intermittent springs could be affected by drilling activities. Approximately 5 intermittent springs lie within or immediately adjacent to the proposed drill pad radii and are the most likely candidates for experiencing temporary effects. Possible indirect effects include temporarily modification of the shallow water table resulting in a decreased discharge to area springs and seeps and/or modification to shallow ground water quality due to mixing of drilling fluids or distinctly separate water bearing zones. Once static equilibrium is re- established, any temporal indirect effects from ground water interception or mixing would cease. Drilling related activities could affect near- surface ground water quality, however design criteria, including the use of biodegradable compounds or 100 percent natural drill additives along with casing-off water bearing zones during construction would minimize this occurrence (Table 2-1). Alternative 3 Surface Water The effects of Alterlative 3 would be the same as Alternative 2, except a total of 27 drill pads will be located in or adjacent to WIZ buffer zones. To access these drill pads, approximately 5.8 acres of new or upgraded road would occur within these buffer zones including 6 intermittent creek crossings and one perennial stream crossing. These locations are displayed on Figure 5. Indirect effects on surface water identified in Alternative 2 would occur under Alternative 3. Deer Creek Ventilation Shaft and E Seam Methane Drainage Wells FEIS 67