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Cemex Vernalis Quarry Mining and Reclamation Project The proposed mining operation would consist of the extraction of 1.7 to 4.0 million tons per year of aggregate materials (sand and gravel) over a 26-to 60-year time period, depending on market conditions. Mining would begin approximately one year after San Joaquin County and Stanislaus County approve the project and would initially utilize a portable aggregate processing plant while the stationary plant is constructed. The operation would be open pit, sand and gravel harvesting and processing. A mining plan was developed based on reviewing over 35 soil borings completed on the Project site. Mining depths would vary from 70 to 120 feet below ground surface, depending on the groundwater level.No mining would occur in the groundwater aquifer. In addition to the mining operation, the project would include a processing plant, a ready mix concrete plant,an asphalt plant,recrushing/recycling of broken concrete and office facilities. The maximum hours of operation for both excavation and processing would be 24 hours per _ day, six days per week (Monday through Saturday), with maintenance occurring on Sundays. A paved entrance to the plant and office site would be constructed off South Costa Ranch Road — (the extension of Koster Road south of Blewett Road). A landscaping screen would be developed within a 50-foot setback along Blewett Road and the northern portion of Kesw South Costa Ranch Road, from Blewett Road to the entrance of the mining facility,to screen operations from the roadways. The entire site would be enclosed with either existing or new fencing. Figure 3-3 and Figure 34 depict the locations,features,and phases of the proposed mining operation. 3.6.1 Site Preparation and Construction Silt Pond Construction While mining Phase I,the Phase IVB VII area would be bermed to create a temporary silt pond — using Phase I and Phase IVB overburden. Once mining is completed in Phase I, it would be used for permanent silt containment and the silt temporarily contained in the Phase IVB VII area would be pumped into the Phase I silt pond. Once Phase lVB and m.....e IV n .. m , ... .0 _ pits will alse beeeme permanent silt pen If additional silt storage is needed during the course of mining,the Phase V IV area would be used as a silt pond. Figures 3-3 33-66 and 3-4 33=7 show the locations of the temporary silt ponds. — Recycled water from the silt ponds and well water would be used for water supply. Once the silt ponds are established,decanted waters from the silt pond would be used in washing the sand and _ gravel,with approximately 25 percent well water being used for washing. Well water would be used in washing sand and gravel until the silt ponds are in operation. Phasing Mining would be divided into nine phases beginning with Phase I. While mining Phase I,the Phase IV VII area would be temporarily bermed to create a silt pond using Phase I and Da a Phase IV overburden. Once mining is completed in Phase I,it would be used for permanent silt containment and the silt temporarily contained in Phase W VII would be pumped into the Phase I Cemex Vernalis Quarry Mining and Reclamatbn Project 4-2 ESA1203015 Final Environmental Impact Report Jane 2008