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' 1.0 Introduction Two monitor well pairs, identified as MW-449 and MW-450, were installed in the ' intermediate zone beneath the North Yard and the former South Yard of the SPX Cooling Technology site located at 200 North Wagner Street in Stockton, California(the Site, Figure 1). The purpose of the monitoring wells is to improve the definition of the distribution of chromium concentrations in the intermediate zone and to monitor the progress of in-situ remediation beneath the North and South Yards. ' Each well pair included two wells that were separated by approximately 10 feet and were constructed with 10 to 15 feet of screen set at different depth intervals in the intermediate zone. The shallow screen settings were designated with an"S"and the deeper screen ' settings were designated with a"D" appended to the well names. The wells were identified as wells MW-449S, MW-449D, MW-450S, and MW450D. The wells were constructed with 4-inch diameter casing to accommodate the installation of submersible pumps to augment production from the remedial well field and enhance cleanup. Dudek submitted a work plan for the installation of the well pairs to the California Department of Toxic Substances Control (DTSC) in May 2012. DTSC approved the work plan on May 30, 2012. The wells were permitted by the San Joaquin County Environmental Health Department on June 21, 2012 (Permits #SR0065155 and ' #SR0065156). Installation of the wells began June 25, 2012. Drilling and construction services were provided by Gregg Drilling(C-57 license#485165) of Martinez, California. Oversight of the drilling and well installations was provided by Steve Dickey, California Certified Hydrogeologist (CHG#386), of Dudek. The well installations were completed on July 2, ' 2012. The wells were developed on July 9 and 10, 2012. 2.0 Summary of Site Hydrogeology The sediments underlying the site are fluvial.and fluvial overbank deposits of the ancestral San Joaquin River delta. The aquifer underlying the site comprises one aquifer unit to a depth of at least 450 feet below ground surface (ft bgs). For the purposes of site ' characterization and aquifer remediation, the local aquifer was divided into four hydrostratigraphic units (Hargis+Associates, 1989). These units are: 1. The shallow zone, which extends from the water table to approximately 80 ft bgs. 2. The 100-foot sand zone, which extends from approximately 80 ft bgs to 110 ft bgs. 3. The intermediate zone, which extends from 110 ft bgs to a depth ranging from 170 ft bgs to 200 ft bgs. 4. The deep zone, which extends from a depth ranging from 170 ft bgs to 200 ft bgs to at least 450 ft bgs. Monitor well pair MW-449 was installed in the intermediate zone beneath the North Yard. Monitor well pair MW-450 was installed in the intermediate zone beneath the Well Completion Report for Monitor Well Pairs MW-449 and MW450 7128-9 SPX Cooling Technologies Dudek ' Stockton, California Page 1 January 2013