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CLEARWATER <br /> G R G U P, I N C <br /> Environmental Services <br /> QUARTERLY GROUNDWATER MONITORING REPORT <br /> SECOND QUARTER 1998 <br /> Ruiz Grocery, <br /> 4491 West Durham Ferry Road,Tracy,CA <br /> CGI Project D-107 <br /> June 11, 1998 <br /> BACKGROUND <br /> Two gasoline USTs and dispensers were removed from the site in 1988 Seven monitoring wells (MW-1 through <br /> MW-7), one groundwater recovery well (RW-1), four soil vapor extraction wells (VW-1 through VW-4), and two air <br /> sparge wells (SW-1 and SW-2) have been installed at the site A domestic well (DW), screened in a deeper water <br /> bearing zone, has also been installed at the site The extent of soil and water contamination has been delineated <br /> Pilot testing has been completed and a remedial action plan prepared based on results Commencing 5/12/98, all <br /> groundwater samples are analyzed for fuel oxygenates(TBA,MTBE,DIPS,ETBE,TAME)by EPA Method 8260 <br /> The work presented here was conducted as part of scheduled quarterly groundwater monitoring as requested by the San <br /> Joaquin County Public Health Services /Environmental Health Division (SJCPHS/EHD) All work was conducted <br /> in accordance with Clearwater's Field Procedures attached <br /> . GROUNDWATER MONITORING FIELD ACTIVITIES <br /> Date of field activities 5/12198 <br /> Wells gauged/sarnpled MW-I to MW-7 and the domestic well (DW),MW-4 gauged only <br /> Analytes tested TPHg, BTEX, Fuel Oxygenates <br /> Analytical methods EPA Methods 8015 (modified), 8020, and 8260 <br /> Laboratory Entech Analytical Labs, Inc, of Sunnyvale, CA <br /> Remarks MW-I and MW-2 will be resurveyed for new groundwater elevations Current <br /> groundwater elevations are not applicable <br /> MW-4 could not be sampled because of surface flooding <br /> GROUNDWATER MONITORING RESULTS <br /> Depth to water 14 52 to 15 99 feet below ground surface(bgs) <br /> Flow direction/gradient Overall, southwest at 0 0033 ft/ft <br /> SPH - wells/thicknesses Sheen in MW-I and MW-2 <br /> TPHg concentration range <50µg/L (DW, MW-3, 5, 6, and 7) to 89,000 gg/L (MW-1) <br /> Benzene concentration range <0 5 gg/L (DW,MW-3, 5, 6, and 7) to 2,000}ig/L (MW-2) <br /> MTBE concentration range <5 0 gg/L (DW, MW-3, 5, 6) to 810 µg/L (MW-2) <br /> Fuel Oxygenates <5 0 gg/L/<20 gg/L except 39 gg/L of TBA in MW-2 <br /> Remarks Slightly convergent flow pattern in vicinity of site Ground water flow is <br /> variable at the site Flow to the southwest was observed in the second <br /> quarter of 1997 Hydrocarbon contamination was not detected in the domestic <br /> well <br /> PROJECT STATUS <br /> On behalf of Ruiz Grocery,Clearwater has received cost pre-approval (dated January 21, 1998)from the Underground <br /> Storage Tank Clean-up Fund for tasks associated with installation, start-up, operation and maintenance of the air <br /> sparging / vapor extraction remediation system, and for four quarters of quarterly groundwater monitoring and <br /> • reporting Remediation system installation is currently being implemented and the system is expected to be <br /> operational by the end of the third quarter of 1998 <br /> 520 Third Street,Suite 104 o Oakland,California 94607 � Telephone 510-893-5160 ` Fax 510-893-59.17 <br />