PERMFILE64371 - Laserfiche WebLink

Home Browse Search

rock between the top of the mining zone and the lowermost extent of the aquifer layers specifically to protect the aquifers from potential communication from the solution mining wells. Thirdly, site conditions are conducive to protecting the Uinta Formation portion of the Upper Aquifer. The mining interval is a confined zone with generally competent, high- quality rock that is not easily fractured. The existing poor water quality in the Lower Aquifer is largely the result of natural dissolution of the minerals from the surface of the Saline Zone. Total dissolved solids (TDS) levels are extremely high, and, near the Dissolution Surface, the water is highly concentrated with sodium bicarbonate/sodium carbonate. If mining fluid were to escape the well, it would rapidly cool, become supersaturated, and precipitate the sodium minerals. In the case of a fracture, this precipitation of minerals would be likely to effectively plug and seal the leak before it could ever leave the Saline Zone. Even if fluid were to enter the Lower Aquifer, mixing with ambient water would speed cooling and precipitation. The primary effect would be deposition of sodium minerals along the Dissolution Surface, the very location from which they are being dissolved naturally. The Mahogany Zone is located between the Upper and Lower Aquifers. While it is not impermeable, the Mahogany Zone does serve as an aquatard and provides additional protection from poor quality water in the Lower Aquifer migrating upward into the Uinta Formation portion of the Upper Aquifer. Furthermore, the structural integrity of the Upper Aquifer, including that of the potential USDW, would be preserved throughout American Soda's proposed commercial mine operations. As discussed in Exhibit Rule 6.5, American Soda's analysis of geotechnical stability indicates that subsidence will not adversely affect the USDW even under aworst-case scenario (Agapito 1998c). As a result of these factors, the aquifer system would be adequately protected, and no significant impacts to the potential USDW are anticipated. G.3 Dewatering and Runoff Plan Surface runoff from the Piceance Site initial processing facility area will be diverted to the evaporation pond (described in Exhibit D, Section D.2.4.1) and will be handled according to management practices identified in Stormwater Permits and Stormwater Management Plans. Adequate freeboard has been provided in the design of the evaporation pond to allow for expected surface runoff from the processing plant area of the Piceance Site, plus the other liquid processing wastes, as well as direct precipitation. Because of the plateau location of the initial processing facility, no other surface runoff will enter the evaporation pond. Runoff from the well field area of the Piceance Site G-10