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PHONE 285 2400 E T CABLE ADDRESS T MOT TACOMAe� {FAX 2 PORTLAND 00 293 8036 STOCKTON I1iT RENO o RICHMOND ' o LOS ANGELES 97 f TIME OIL co . 6 TS 2737 WEST COMMODORE WAY SEATTLE,WA 98199 1233 r PRODUCTS E P O BOX 24447 SEATTLE,WA 98124-0447 July 31, 2000 Mr Harlin Knoll San Joaquin County Pubic Health Services Environmental Health Division P O Box 2009 Stockton, California 95201 RE Submittal of Second Quarter 2000 Groundwater Monitoring Report for Jackpot Food Mart, 14000 E Highway 88, Lockeford, California (Property No 04-049) Dear Mr Knoll, At the request of the San Joaquin County Public Health Services Environmental Health Division (PHS/EHD), an environmental investigation was implemented at the subject site in December 1994 to evaluate the extent of hydrocarbon-impacted soils and to determine whether or not groundwater had been impacted A total of four groundwater mon:coring wells were installed during this investigation In July 1996, six additional groundwater monitonng wells were installed on and off of the subject site to assist in defining the extent of groundwater impacts In August and September 1999, SECOR installed a vapor extractionlair sparging system at the subject site to remediate hydrocarbon-impacted soils and groundwater System operation began December 13, 1999 Please find enclosed SECOR's "Quarterly Monitoring Report, April - June 2000" dated July 20, 2000 This document presents analytical results and field observations collected during Second Quarter 2000 groundwater sampling Second Quarter 2000 Groundwater Sampling Results - On June 1, 2000, samples were collected from each of the groundwater monitoring wells (MW-1 through MW-10) at the subject site by a representative of SECDR Prior to purging, the depth to water in each well was measured to evaluate elevation, flow direction, and gradient As noted in the attached report, groundwater with a southwesterly flow direction and a gradient of 0 03 ft/ft was encountered in the wells at depths of 66 36 feet to 76 38 feet below ground surface Free product was encountered In MW-1 (3 64 feet) The locations of the wells are identified on Figure 2 of the attached report Since the February 2000 sampling event, groundwater elevation increased each of the wells by 0 09 feet to 5 22 feet, resulting in an overall average increase in groundwater elevation of 0 98 feet across the site Changes in groundwater elevation are most likely a result of seasonal variation Groundwater gradient and flow direction remained consistent with previously collected data Table 1 in the attached report summarizes groundwater elevation data collected to date Analyses identified elevated concentrations of hydrocarbons and/or oxygenates in the samples collected from MW-3 (458 ppb TPH-g, 90 5 ppb benzene, 9 8 ppb toluene, 40 5 ppb ethylbenzene, 71 8 ppb xylenes and 1 3 ppb MTBE), MW-4 (1B7 ppb TPH-g, 7 8 ppb benzene, 4 7 ppb ethylbenzene, 0 6 ppb xylenes, 9 3 ppb MTBE, and 50 ppb TBA), MW-5 (118 ppb TPH-g, 4 7 ppb benzene, and 6 6 ppb MTBE), and MW-9 (51 ppb TPH-g and 7 7 ppb benzene) Lower concentrations of oxygenates were found in the sample collected from MW-2 (1 5 ppb MTBE) Hydrocarbons were not detected in the samples collected from MW-6, MW-7, MW-8, and MW-10 No sample was submitted from MW-1 due to the presence of free product Table 2 and