2012-06-20_PERMIT FILE - C2010089A (9)

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Lithology. Lithology governs the water yielding ability, the aquifer characteristics and the chemical quality of the ground water. As seen in Section 2.04.6, the lithology of the NHN Mine area is extremely variable. Shallow aquifers of the area consist of unconsolidated valley deposits of the quaternary system and the stratigraphically variable sandstone, shales and coals of Cretaceous Age (Dakota, and Burro Canyon Formations). Deeper aquifers consist of the varicolored Morrison Formation and the Entrada Formation both of Jurassic Age. The variability of lithology within each of the aquifers creates a complex hydrologic system. Table 2.04.5 -1 is a summary chart adapted from Boettcher (1972) describing the physical and hydrologic character of the water bearing formations mentioned above. Not included in Table 2.04.5 -1 is water quality which is controlled by the reaction of the ground water with the aquifer and the ground water retention time (Hem, 1970). In addition, ground water yields and uses are given. It must be noted that these are generalizations, and these hydrologic properties can vary greatly within the formations. Structural Controls. The New Horizon North Mine area lies in the Colorado Plateau Physiographic Province within the Canyon Lands Section (Price and Arnow, 1974). This section is an upwarped plateau containing several large folds, laccolithic mountains that rise above the plateau surface, deeply incised drainages and an intricate set of deep canyons (Lohman, 1965; Irons et al., 1965). Structural control on the shallow ground water in the area, i.e., upper Dakota Sandstone and alluvium, appears to be insignificant. This is principally due to the large extent of sandstone outcrops. This allows recharge to occur along topographic highs rather than structural highs with water table conditions predominating However, an artesian head may be developed if a lesser coal bed or sandstone aquifer is confined by impermeable strata. Piezometric surfaces in deeper formations such as the lower Dakota, Burro Canyon, Morrison and Entrada Formations whose ground water is under artesian pressure closely conforms to structural influence (Lohman, 1965). In these formations, recharge occurs along structural highs, i.e., an outcrop which corresponds to the limb of a syncline or the fractured crest of an anticline. Movement of water within these formations is down dip with faults acting as boundary conditions or conduits for flow. As an example, such artesian waters are the principal suppliers of water to areas near Grand Junction which is 52 miles north of WFC's New Horizon North area. Regional Ground Water Recharge, Movement and Discharge. The principal areas of ground water recharge are in the plateaus and mountains, which receive the greater amounts of annual precipitation. Ground water movement is from areas of recharge to areas of natural discharge, which include springs, gaining reaches of springs and areas of phreatophyte growth. Ground water consumption by phreatophytes and hydrophytes in Section 2.04.5 Page 6 April 2011