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�ECOVEDD GROUND ZERO ANALYSIS INC. FEB 2 o 2004 coy ENVIRONMENT HEALTH 1714 Main Street PERMIT/ L6 Escalon,California 95320-1927 Telephone:(209)838-9888 Facsimile:(209)838-9883 February 18,2004 Mr. James L.L.Barton Regional Water Quality Control Board Central Valley Region 11020 Sun Center Drive,#200 Sacramento,CA 95670 Subject: Intended Modification to Interim Groundwater Treatment System Speedy Foods, 8200 N. Highway 99, Stockton, CA Dear Mr.Barton: As we discussed recently by telephone, Ground Zero proposes to modify the existing interim groundwater treatment system at the subject site. CURRENT CONFIGURATION The system currently consists of a single extraction well (MW1), dual 2,000-pound GAC units configured in series, a 200-pound"polish"GAC unit,a 4800-gallon temporary storage tank, and a discharge line. The system currently operates at approximately 1.0-1.7 gpm from the single extraction well. Ground Zero personnel currently monitors the system on a weekly basis. Weekly samples are collected from the effluent (full suite of analyses) as well as after each 2,000-pound GAC unit (Cl and C2 for VOCs only). Monthly samples are collected from the treatment system influent(full suite of analyses). ANTICIPATED MODIFICATIONS As we discussed, Ground Zero has been evaluating the feasibility of adding a low-profile air stripper to the treatment system to limit the consumption of carbon and to allow for an increase in the capacity of groundwater being treated. Ground Zero has tentatively selected a NEEP Shallow Tray air stripper Model 1341-P, which would have a capacity of up to 10 gpm. Information on the air stripper is attached. The treatment system as modified would then direct extracted groundwater (from one or more wells) into a 275-gallon holding tank equipped with an influent feed pump, which would feed influent water through the air stripper into to the effluent sump. The system performance estimate provided by the manufacturer predicted that the air stripper would reduce MTBE in the influent to less than 10 ppb (modeled at 19,000 ppb influent @ 5 gpm). The effluent sump pump would feed the partially treated water to the GAC units, which would remain in series to further reduce contaminants to below detection limits prior to discharge. According to Jan Sudomeir of the San Joaquin Valley Unified Air Pollution Control District (APCD), no authority to construct (ATC) or permit to operate (PTO) will be required as long as untreated air discharges are below 2 pounds per day. Based upon system operation to date, we have been removing an estimated 0.3 to 0.7 pounds per day of gasoline constituents. G:IGROUNDZE1TULEBURG1Reportslbarton_sysmod2.doc ��