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I , SECOR July 12 1995 International Incorporated I Conoco Inc P.O Box 2197 Room PO - 3038 Houston, Texas 77252-2197 ' I ATTENTION: Ms Linda S. Thompson i Project Manager - Remediation Technology SUBJECT: Annual Monitoring Report, Apnl-June 1995 Former Econo Gas Station 4325 East Washington Street Stockton, California i Ms Thompson This report presents the results of annual groundwater monitoring and sampling conducted at Conoco Inc 's former Econo Gas Station, located at 4325 East Washington Street, Stockton, California (the Site) on May 4, 1995. This report also summarizes the status of soil remediation at the Site for the period between April 1 and June 30, 1995 GROUNDWATER MONITORING AND SAMPLING Groundwater monitoring and sampling were conducted in accordance with the procedures specified in the State of California LUFT Manual Prior to sampling, depth to water in each groundwater monitor well was taken and subjective analyses performed The subjective analyses consisted of purging approximately 4 to 10 volumes of water using hand bailing methods or until groundwater parameters of pH, temperature, and conductivity stabilized as measured by portable meters calibrated to a standard buffer and conductivity standard. Groundwater samples were then collected by lowering a clean disposable bailer into the well and collecting a representative sample of the formation water If the well was slow to recover, the sample was not collected until the water level approached 80 percent of its initial level The groundwater sample was slowly transferred to laboratory-cleaned sample containers, sealed with Teflon lined caps, and transferred to cooled storage i Groundwater samples were submitted, under appropriate chain-of-custody to Trace Analysis j Laboratory In Hayward, California for analysis of total petroleum hydrocarbons as gasoline (TPHg) using the DHS Method, and benzene, toluene, ethylbenzene, and xylenes (BTEX) using the U S Environmental Protection Agency (EPA) Methods 80201602. Groundwater Elevation Data A summary of data regarding groundwater levels through May 4, 1995 is presented in Table A. Since the last annual sampling event, groundwater elevations have generally increased 4 5 feet across the Site The groundwater flow direction is toward the southeast at an approximate gradient ,CONOCOInc # SECOR Interrtahonal, Inc � C0n0c01N0700-008\Stockton 295 July 12, 1995 1754- Oth Sircel Sacramento CA 95816-7004 (916)456-4-333 (916)456-0110IAX