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r. <br /> r j P H 0 N L 285 2y <br /> CABLE ADDRESS Ti r.0 L <br /> SEATTLE TE (FAX) 206 283 8036 <br /> TACOMA " <br /> PORTLAND <br /> OS ANGELES y �; ON <br /> TIME OIL CO . <br /> x�a — <br /> n s 2737 WEST COMMODORE WAY SEATTLE WA 98199 1233 <br /> rRooucrs ' P O BOX 24447 SEATTLE WA 98124-0447 <br /> TIME TESTED E <br /> Mr Harlin Knoll <br /> San Joaquin County Public Health Services APR 1 200-1 <br /> Environmental Health Division <br /> P O Box 2009 ENVIRONMENT HEALTH <br /> Stockton, California 95201 PERMIT/SERVICES <br /> RE Submittal of"Quarterly Monitoring Report, January—March 2003"for <br /> Jackpot Food Mart, 14000 E Highway 88, t_ockeford, California (Property No 04-049) <br /> Dear Mr Knoll, <br /> An environmental investigation was implemented at the subject site in December 1994 to evaluate the extent <br /> of hydrocarbon-impacted soils and to determine whether or not groundwater had been impacted Four <br /> monitoring wells were installed during this investigation (MW-1 through MW-4) In July 1996, six additional <br /> monitoring wells were installed on and off of the subject site to assist in defining the extent of groundwater <br /> impacts (MW-5 through MW-10), and quarterly monitoring was implemented In August and September <br /> 1999, SECOR installed a vapor extraction/air sparging system at the subject site to remediate hydrocarbon- <br /> impacted sods and groundwater System operation began December 13, 1999 <br /> �y Please find enclosed SECOR's "Quarterly Monitoring Report, January - March 2003" dated April 4, 2003 <br /> This document presents analytical results and field observations collected during First Quarter 2003 <br /> groundwater sampling, and discusses the efficiency of the remediation system currently in operation <br /> First Quarter 2003 Groundwater Sampling Results <br /> On January 16, 2003, groundwater samples were collected from each of the monitoring wells at the subject <br /> site (MW-1 through MW-10) Prior to purging, the depth to water in all wells was measured to evaluate <br /> elevation, flow direction, and gradient As noted in the attached report, groundwater with a south- <br /> southwesterly flow direction and a gradient of 0 03 ft/ft was encountered in the wells at depths of 70 94 feet <br /> to 84 98 feet below ground surface Free product was not encountered to any of the wells The locations of <br /> the wells are identified on Figure 2 of the attached report <br /> Since the November 2002 sampling event, groundwater elevation decreased in MW-5 by 4 19 feet and in <br /> MW-10 by 5 06 feet, while it increased by 0 00 feet to 0 77 feet in the remaining wells These changes <br /> resulted in an overall average decrease in groundwater elevation of 0 55 feet across the site Changes in <br /> groundwater elevation are most likely a result of seasonal variation and operation of the remediation system <br /> Groundwater gradient and flow direction remained consistent with previously collected data Table 1 in the <br /> attached report summarizes historical groundwater elevation data <br /> Hydrocarbons were identified in the sample collected from MWA (3,200 ugll TPH-g, 2 1 ugll benzene, 3 8 <br /> ugll ethylbenzene, and 107 ug/l xylenes) TPH-g and BTEX were not identified in the groundwater samples <br /> submitted from MW-2 through MW-10 Analyses identified low concentrations of MTBE in the samples <br /> collected from MWA (1 5 ug/1) and MW-9 (1 3 ugh), however, none of the other samples contained <br /> detectable concentrations of MTBE Other fuel oxygenates (TBA, DIPS, ETBE,and TAME)were not present <br /> at detectable concentrations in any of the samples Table 2, Table 3, and Figure 3 in the attached report <br /> summarize groundwater analytical data and laboratory reports are included as Attachment 2 <br /> The highest concentrations of hydrocarbons appear to remain onsite in the vicinity of the pump islands (MW- <br /> 1) When compared to the November 2002 sampling data, hydrocarbon concentrations decreased in MWA <br /> while they remained essentially"non-detect" in the remainder of the wells Since the initiation of remediation <br /> efforts, hydrocarbon concentrations across the site have substantially decreased <br />