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The <br /> proposed project is designed to limit all mining excavations to above the groundwater table at the <br /> time of mining. A natural increase in the water table levels is unavoidable and counteracting or <br /> arresting such an increase is costly if not infeasible (i.e., through pumping wells used to reduce <br /> groundwater levels). However, measures can be implemented to maintain an adequate separation <br /> between the mining surface and the upper water table surface. These measures are presented <br /> below as mitigation measures developed to ensure that impacts associated with an increased <br /> groundwater surface remain less than significant. See Draft EIR,pp. 4.8-21 to 4.8-24. <br /> Mitigation Measures <br /> Mitigation Measure 4.8.1 a: Excavation/Groundwater Separation. The project applicant, shall, at <br /> no time, extend the depth of excavation below the depth of the water table and shall maintain a <br /> vertical separation between the water table and the active mining surface. Determination of the <br /> water table depth shall be based on historic regional groundwater levels for the unconfined <br /> aquifer. The vertical separation shall be determined appropriate by a California-certified <br /> hydrogeologist or civil engineer but shall not be less than five feet. (Draft EIR,p. 4.8-23.) <br /> Mitigation Measure 4.8.1b: Groundwater Elevation Monitoring Schedule. The applicant shall <br /> monitor groundwater to ensure that the vertical separation between the nearest groundwater <br /> surface and the lowest point of the active excavation and reclaimed phases is maintained as <br /> required by the California-certified hydrogeologist and at no less than five feet. The groundwater <br /> levels shall be monitored on-site prior to and during all phases of excavation,prior to the <br /> initiation of excavation for each phase, and in the reclaimed phases. Groundwater shall be <br /> continually monitored in the active mining area on a bimonthly basis,within a week following <br /> each large rainstorm from October through April, and monthly during the remainder of the year. <br /> Reclaimed phases shall be monitored once monthly. Monitoring technique shall be based on <br /> recommendations and approval by a California-certified hydrogeologist. (Draft EIR, p. 4.8-23.) <br /> Findings: <br /> Based on the whole record, this Commission finds that with implementation of Mitigation <br /> Measures 4.8.1 a and 4.8.1 b, impacts from groundwater seepage are reduced to a less than <br /> significant level. (Draft EIR,p. 4.8-24.) <br /> Impact 4.8.2 <br /> Accidental spill, leaks, or improper disposal ofpetroleum fuel would increase the potential for <br /> degradation ofgroundwater quality over the life of the project. (Draft EIR,p. 4.8-24.) <br /> Significance Before Mitigation: Potentially Significant. <br /> Facts: The project requires heavy equipment and the use of other vehicles associated with <br /> normal mining operations. Onsite equipment also includes the stationary processing plant and <br /> associated conveyors. The vehicles and stationary equipment require fuels and lubricants that <br /> would be stored in various quantities on the project site (see Section 4.11 of the Draft EIR, <br /> Hazards and Hazardous Materials). Accidental discharge to the ground of these liquid petroleum <br /> 19 <br />