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ENVIRONMENTAL ASSESSMENT <br /> Groundwater quality in Alkali Gulch is monitored by two wells, MW-7EAA (upgradient) and MW-8EAA <br /> (downgradient).The water quality in both monitoring wells is calcium/magnesium sulfate water and the <br /> water does not meet drinking water standards. <br /> Cliff House Sandstone Groundwater <br /> The Cliff House Sandstone is the uppermost bedrock unit in the King II Mine area and therefore dominates <br /> surface exposures of bedrock.The thickness of the unit averages 350 ft and the formation is dissected by <br /> drainages originating from mesa tops (OSMRE 2017). The Cliff House is a marine, medium-grained <br /> calcareous sandstone that thins to the east. Monitoring well clusters installed by GCCE have demonstrated <br /> that the Cliff House is basically unsaturated in the Project Area but does contain minor water-bearing <br /> fractures. Most wells screened in the Cliff House were either dry or became dry shortly after drilling <br /> (OSMRE 2017). <br /> Menefee Formation Groundwater <br /> The Menefee Formation is a non-marine assemblage of sandstones, shales, siltstones, and coals. The <br /> thickness in the Project Area is around 300 ft and this unit is the main coal-bearing unit mined in the King <br /> I and King II mines (OSMRE 2017). <br /> The upper Menefee, which is the part of the Menefee Formation targeted for coal mining, is not known <br /> to be an aquifer(RHS 2016a).The interval of the upper Menefee in the Project Area is known locally to be <br /> unsaturated based on exploration drilling by GCCE (OSMRE 2017).The lower Menefee may be an aquifer <br /> in the southern part of the CIAA as the formation deepens to the south with a regional dip of two to three <br /> degrees (OSMRE 2017). <br /> Point Lookout Sandstone Groundwater <br /> The Point Lookout is the lowest stratigraphic unit in the Project Area and consists of near-shore marine <br /> sands grading upward into barrier sands. The formation is dominated by fine sandstones and silty <br /> sandstones.The groundwater yield is low (OSMRE 2017). <br /> It is likely that many of the deep bedrock wells in the Project Area that are screened in the lower Menefee <br /> are drawing water from fractured sections of the upper Point Lookout because of possible hydraulic <br /> connections between the upper Point Lookout and the lower Menefee (OSMRE 2017). <br /> 3.4.2.2 Environmental Effects <br /> Effects of Alternative A—Proposed Action <br /> The Proposed Action would consist of expansion of the King II Mine workings underneath and west of East <br /> Alkali Gulch and construction of the East Alkali Gulch low-cover crossing (Section 2.2.3). A total of <br /> approximately 20 acres would be disturbed by the Project over the life of the mine.This would include 10 <br /> acres for construction of the low-cover crossing at the outset of the Project and 10 acres cumulatively for <br /> all other dispersed surface disturbances of variable sizes that would occur over the life of the mine. The <br /> Gulch crossing would likely be in bedrock below about 25 to 50 ft of alluvial material and would be an <br /> extension of the existing underground workings in the King II Mine. Construction of the crossing would <br /> involve trenching in the valley floor of The Gulch and construction activities that when completed would <br /> Dunn Ranch Area Coal Lease by Application COC-78825 and Mine Plan Modification EA 3-14 <br />