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Prince Albert Mine 110(d) Permit Application Exhibit U - EPP <br />U (7.a.2) _ Hydrogeology <br />Negative effects on ground water resources from mining operations at the Prince Albert Mine are <br />expected to be very limited due to the characteristics of the local and regional hydrogeologic system. A <br />generalized hydrogeologic cross - section of the area is included as Figure U.7.3 "Generalized Hydrologic <br />Cross - Section H - H" (see also Exhibit A, Figure A.1 "General Location Map" for cross - section location). <br />The primary source of ground water that could be affected during mining is the Salt Wash member of the <br />Morrison Formation, which is considered relatively permeable and transmissive due to fracturing. The <br />Salt Wash sandstone is jointed in an orthogonal pattern that strikes northeast - northwest with fractures that <br />generally completely transect individual sandstone beds which are two or more feet thick. Fractures are <br />two to three feet apart and appear to be transmissive in the subsurface environment because they display <br />well developed Liesegang banding parallel to the fractures as well as along some bedding surfaces. The <br />sandstone itself is relatively impermeable, displaying no open pores during petrographic analysis. <br />The Salt Wash member is capped by the Brushy Basin member of the Morrison Formation, although it <br />has almost completely eroded away in the mine permit area. The Brushy Basin Member is composed <br />largely of varicolored bentonitic shale and mudstone with local lenses of conglomerate that give it its <br />characteristic low permeability. It is considered relevant to the mine site hydrologic condition primarily <br />due to its potential to limit recharge to the Salt Wash Member up gradient of the mine site where it is still <br />present under the highly transmissive Dakota Sandstone Formation. <br />The Salt Wash Member, in turn, overlays the Wanakah (ex. Summerville) Formation, which is up to 90 <br />feet thick in the Club Mesa area. The Wanakah Formation consists of red shale alternating with <br />mudstones in even, horizontal beds that were deposited in a quiet transitional environment following the <br />retreat of marine conditions at the beginning of the Glen Canyon time. The lithology of the Wanakah and <br />its stratigraphic geometry are strong influences on its hydrologic properties. The very low hydraulic <br />conductivity ( <1.0x10 -8 cm /sec) of this formation make it a very effective aquitard that will severely limit <br />the potential for the down ward migration of any affected ground water from the Salt Wash member <br />through the moderately transmissive Carmel /Entrada formation and to the regional water table in the <br />Kayenta Formation. <br />U (7.b) Ground Water Quality and Management <br />The potential for the downward migration to the regional water table of any contaminants from the <br />mining operation in the Salt Wash Member is limited by the Wanakah aquitard, which lies below the Salt <br />Wash Member of the Morrison Formation. No ground water has been encountered to date in the <br />underground workings of the Prince Albert Mine. The only water encountered in the nearby and currently <br />inactive Buckshot Mine, an underground mine similar to the Prince Albert, consisted of small quantities <br />from direct infiltration through significant fractures or as a very small perched pool on top of a clay lens. <br />Rimrock Exploration & Development Page 26 of 39 <br />