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i If <br />' I <br /> f. The final reclamation of any phase of excavation shad be completed within two years of <br /> the commencement of the final reclamation process. Excavatio <br /> n shall be limited so that <br /> at any point of time a maximum of one phase is being reclaimed while one phase is being <br /> excavated. (Development Title Section 9-1415.2(o}) <br /> g. Initial excavation shall begin in Phase 2 away from any sensitive structures such as <br /> canalsPi elin� and roadways to allow possible defection of any weak soil strata and/or <br /> perched zones of saturation. When the initial excavation has reached full depth, large <br /> block samples shall be obtained by a geotechnical engineer to determine the actual <br /> strength properties and analyze any possible change in the computed factors of safety. <br /> Additionally, for every 25 feet of excavation depth in each phase, an inspection by a <br /> geotechnical engineer shall be performed that evaluates whether the excavation has <br /> penetrated soil conditions other than those that were anticipated in the slope stability <br /> analysis. The inspection report shall determine it soil conditions exist that would decrease <br /> the anticipated factor of safety and include recommendations for revisions to the slopes <br /> in the affected area <br /> The geotechnical engineer for the above inspections shall be selected by San Joaquin <br /> County with the applicant being responsible for the cast of the professionalized services <br /> plus an administrative fee of 15 percent. <br /> h. Install three monitoring wells to a depth of ten feet below the invert elevation of the <br /> California Aqueduct. The wells shall be located between een Phase 2 sedimentation ponds <br /> and the California Aqueduct for monitoring of any shallow perched groundwater. The <br /> applicant shall monitor water levels quarterly to ensure that I a zone of saturation forms <br /> beneath the aqueduct, it does not rise to a level higher than the invert of the aqueduct. <br /> The quarterly! monitoring reports shall be sent annually to Development Services Division. <br /> Such monitoring wells are not required-if sedimentation ponds are maintained below the <br /> invert elevation of the Aqueduct <br /> L All phases of the mining operation shall be dry pits. The maximum depth of mining shalt <br /> R be sic feet above the high level of the water table, but in no case shall the excavation be <br /> more than 150 feet below original grade. As a basis for initial and ongoing mining <br /> depths, the applicant shall submit annually to Development Services Division quarterly <br /> k reports monitoring the water depths for a minimum of ten water supply wells around the <br /> general perimeter of the permitted mining area In the event that the applicant is unable <br /> to obtain or retain at least ten existing water wells for water level measurements, the <br /> applicant shall procure.new wells for monitoring purposes at locations acceptable to <br /> Development Services Division. The applicant shall provide a verifiable bench mark at <br /> each well site that can be referenced for compliance monitoring. <br /> t <br /> Based upon the water depth monitoring reports, Development Services Division may <br /> recalculate the high level elevation of the water table, thereby adjusting the maximum <br /> allowed depth of mining. Under no tiro instances shall the maximum allowed depth of <br /> mining be increased. <br /> Based upon current and recent historic groundwater level data,the groundwater elevation <br /> beneath the site is approximately 87 feet above mean sea level. Based on that elevation, <br /> F the minimum mining elevation shall not be below 93 feet mean sea level in all phases. <br /> Conditions of Approval - 5 - OX-91.5 <br /> I <br />