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CLEARWATER <br /> G R O U P, I N C <br /> Environmental Services <br /> QUARTERLY GROUNDWATER MONITORING REPORT <br /> FOURTH QUARTER 1996 <br /> Ruiz Grocery,4491 West Durham Ferry Road,Tracy, CA <br /> November 12,1996 <br /> BACKGROUND <br /> Two gasoline USTs and dispensers were removed from the site in 1988 Seven monitoring wells (MW-1 <br /> through MW-7), one groundwater recovery well (RW-1), three soil vapor extraction wells (VW-1 <br /> through VW-3), and two air sparge wells (SW-1 and SW-2) have been installed at the site A domestic <br /> well, screened in a deeper water bearing zone, has also been installed at the site The extent of soil and <br /> water contamination has been delineated Pilot testing has been completed and a remedial action plan <br /> prepared based on results - <br /> GROUNDWATER MONITORING FIELD ACTIVITIES <br /> Date of field activities 10/18/96 <br /> Wells monitored/sampled MW-1 to MW-7, and the domestic well <br /> Analytes tested TPHg,BTEX, and MTBE <br /> Analytical methods EPA Methods 8015/8020 (modified) <br /> Laboratory American Environmental Network, Inc of Pleasant Hill, CA <br /> Remarks MW-1 was not sampled due to presence of SPH A depth to water <br /> measurement could not be obtained from the domestic well due to <br />. wellhead plumbing <br /> GROUNDWATER MONITORING RESULTS <br /> Depth to water 13 98 to 15 54 feet below ground surface(bgs) <br /> Flow direction/gradient Northwest at 0 0013 ft/ft <br /> SPH - wells/thicknesses MW-1 / <0 01-foot thick heavy sheen <br /> TPHg concentration range <50 ppb (MW-3,4, 5,6, and 7) to 27,000 ppb (MW-2) <br /> Benzene concentration range <0 5 ppb (MW-3,4,5,6,and 7) to 3,000 ppb (MW-2) <br /> MTBE concentration range <5 0 ppb (MW-3 and 4) to 3,500 ppb (MW-2) <br /> Remarks Groundwater flow is generally consistent with previous measurements <br /> and the extent of the contaminant plume remains delineated The <br /> domestic well remains free of detectable contamination <br /> PROJECT STATUS <br /> A meeting between Ms Stella Ruiz, San Joaquin County Public Health Services officials, and <br /> Clearwater Group, Inc was held on November 1, 1996 in order to finalize the corrective action plan for <br /> the site A remedial system consisting of concurrent air sparging and soil vapor extraction was settled <br /> upon Soil vapors will be extracted from vertical wells during periods of low water table conditions <br /> (i e >12 feet bgs) and from a horizontal well, installed at the base of the system utility trench, during <br /> high water table conditions (i a <12 feet bas) A brief letter describing the final corrective action plan <br /> will be submitted to San Joaquin County by late November 1996 Quarterly groundwater monitoring will <br /> continue as requested by San Joaquin County <br /> 520 Third Street,Suite 104 o Oakland,California 94607 o Telephone 510-893-,, o Fax 510-893-5947 <br />