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Date: June 13, 2000 <br /> Quarter: IQ00 <br /> ARCO QUARTERLY GROUNDWATER MONITORING REPORT <br /> Facility No.: 4493 Address: 205 North Center Street, Stockton, CA <br /> ARCO Environmental Engineer: Chuck Carmel <br /> Consulting Co./Contact Person: SECOR International Incorporated/Rusty Benkosky <br /> Consultant Project No.: 077.41907.701 <br /> Primary Agency/Regulatory ID No.: San Joaquin Count Environmental Health Department <br /> Assembly Bill 681 Status: Property Owned by City of Stockton <br /> WORK PERFORMED THIS QUARTER (First Quarter- 2000): <br /> 1. Conducted quarterly groundwater monitoring and sampling. <br /> 2. Prepared and submitted quarterly groundwater monitoring report. <br /> WORK PROPOSED FOR NEXT QUARTER (Second Quarter— 2000): <br /> 1. Conduct quarterly groundwater monitoring and sampling. <br /> 2. Prepare and submit quarterly groundwater monitoring report. <br /> 3. Install three groundwater monitoring wells and advance one soil boring for vertical definition. <br /> QUARTERLY RESULTS SUMMARY <br /> Current Phase of Project: Monitorin Assessment <br /> Frequency of Groundwater Sampling: MW-1 through MW-4 are sampled guarterly. _ <br /> Frequency of Groundwater Monitoring: Ouay&rly <br /> Is Free product(FP)Present On-Site: No <br /> Current Remediation Techniques: _ Natural Attenuation <br /> Approximate Depth to Groundwater: 12.12 to 13.21 <br /> Groundwater Grmdient: EEL-NUtheM is Q.0-05 <br /> DISCUSSION: <br /> TPHg was reported in three of the four wells sampled this quarter at concentrations ranging from 52.2 ppb(MW-2 <br /> to 5,330(MW-4). Benzene was reported in two wells sampled this quarter at a maximum concentration of 298 pp <br /> (MW-4). MtBE was reported in two wells sampled this quarter at concentrations of 246 ppb(MW-3) and 4,960 <br /> (MW-4).TCE was detected in two wells sampled at concentrations of 227 ppb(MW-1)and 96.6 ppb(MW-2) <br /> (upgradient and crossgradient wells). PCE was detected in one well this quarter at a concentration of 2.74 ppb <br /> (MW-1). Concentrations were generally consistent with historical data. Groundwater elevations across the site <br /> increased by an average of 2.31 feet this quarter and flow was east-southeasterly with a hydraulic gradient of <br /> 0.005 ft/ft. ARCO station demolition activities were completed in April 1999 and this site is currently vacant. <br /> h <br /> y <br /> 1 <br /> s <br /> :... ..�.,:.. ,. '..:...-.'.• -. ., _..e m s......w..s...., ..vex�......0�_.fi. ..-•,.,_ _�.a. <br />