2008-01-15_PERMIT FILE - M2007044 (2)

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~~~~ c_-'''! Interoffice Memo TO: FRANK FILAS FROM: DICK WHITE, CERTIFIED PROFESSIONAL GEOLOGIST #8792 DATE: JANUARY 8, 2008 SUBJECT: GEOLOGICAL INTERPRETATION OF BEAVER MESA WATER- BEARING ZONES BASED ON EXPLORATION DRILLING RESULTS In their review of the Whirlwind permit application, the Bureau of Land Management (BLM) and the Division of Reclamation, Mining and Safety (DBMS) asked if our exploration drilling activities could provide additional geologic and ground water information for the Whirlwind Mine area. Based on the 2007 drilling on Beaver Mesa and similar mesas throughout the Colorado Plateau where I have managed exploration drilling programs fox 30 years, I believe that the characterization of the water-bearing sandstone lenses located above the ore zone in the permit applications is generally accurate. The results of the packer tests conducted by Umetco in Boring BM00-1 (see Appendix C of the applications) are especially relevant because they provide quantifiable data for each of the sandstone lenses encountered near the proposed mine development. The ground water discussion in the permit applications does not, however, completely characterize the shape and continuity of these water-bearing zones. The sandstone lenses within the Brushy Basin unit of the Morrison Formation were formed by ancient stream and river channels flowing across a slowly subsiding plain. These channels were limited in width, varied in depth, and meandered within the surrounding landscape. As with streams today, coarser-grained sands were deposited within the areas of the channels while finer-grained materials were deposited within the much larger floodplain areas. This resulted in the creation of isolated sandstone lenses within the massive mudstone deposits of the Brushy Basin. These lenses are irregular in shape and size and seldom continuous over a large area because the stream locations usually shifted over time. In contrast, the basal sandstones and conglomerates of the Burro Canyon Formation coalesce into a more continuous unit with fewer and smaller interbedded shales. When the formations are relatively flat, as is the case on Beaver Mesa, the Brushy Basin sandstone lenses do not typically contain much ground water. Ground water, if encountered, is typically found along the base of the sandstone lenses and is unconfined (under no pressure). In these cases, ground water recharge is almost non-existent due to the overlying mudstones and shales that prevent ground water from percolating downward. Since the Burro Canyon forms the majority of the mesa cap, it receives more recharge than the underlying Brushy Basin. However, runoff and evapo-transpiration preclude significant quantities of water from entering the formation in this semi-arid environment. Recharge may be more extensive where perennial streams flow over extensive outcropping of the sandstone zones. In those locations where the formations dip steeply, confined ground water (i.e., under pressure) may be encountered at depth. Neither of these conditions exist on Beaver Mesa.