FIELD DOCUMENTS AND WORK PLANS 1987

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yT HARGISJ ASSO`IATES, INC. Consultants in 'Hydrogeology December 19, 1986 VIA FEDERAL EXPRESS Mr. David Bates THE MARLEY COOLING TOWER COMPANY 5800 Foxridge Drive Mission, KS 66202 RE: Additional Monitor Wells at the Stockton Facility Dear Mr. Bates: Pursuant to our telephone conversation on December 10, 1986, additional monitor wells are required to determine the extent of chromium in ground- water downgradient of the Marley Cooling Tower Company (MCTC) facility in Stockton, California. The results of laboratory analyses of groundwater samples collected in November at the MCTC facility indicate that the extent of groundwater containing concentrations of chromium greater than 0.05 milligrams per liter (mg/1 ) has not been defined (Figures 1 and 2) . The concentration of chromium in groundwater collected from shallow monitor well MW-303 was 0.16 mg/1 . The concentrations of chromium in groundwater samples collected from intermediate monitor wells MW-323 and MW-324 were 0. 19 mg/l and 0.13 mg/1 , respectively. Definition of the extent of groundwater that contains concentrations of chromium greater than 0-.-0471 requires the construction of wells that produce groundwater containing less than 0.05 mg/l of chromium. Consequently it is necessary to drill one shallow and three intermediate monitor wells farther downgradient. It is recommended that one additional shallow monitor well be con- structed adjacent to monitor wells MW-310, MW-325, and MW-364 (Figure 1) . One of the intermediate wells should be located in the vacant lot west of monitor well MW-323, a second on Washington Street between Wagner and Dawes Avenues, and a third on Coolidge Avenue south of Washington Street (Figure 2) . The owner of the vacant lot west of Franklin High School , where the first of these wells should be drilled, has not been determined and access is uncertain. It should be possible to locate the monitor well on Coolidge Avenue in the road right-of-way, but the road will have to be temporarily closed to through traffic during drilling. No access problems are antici- pated for the intermediate monitor well on Washington Street.