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PHONE 285 2400 CABLE ADDRESS TImOIL SEATTLE TE (FAX) 206 283 8036 TACOMA N PORTLAND STOCKTONRENO T LICHMOND OS ANGELES 4 23 Nr 7 o K a s TS 2737 WEST COMMODORE WAY SEATTLE WA 98199-1233 PiiDPUCTS �TM P O BOX 24447 SEATTLE WA 98124-0447 TIME TESTED E February 13, 1996 Mr Harlan Knoll San Joaquin County Public Health Services Environmental Health Division P O Box 2009 Stockton, California 95201 RE Submittal of Fourth Quarter 1995 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 (PHSIEHD), an additional 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 Based on the results of the investigation, Time Oil has implemented groundwater monitoring Please find enclosed Science & Engineering Analysis Corporation's (SECOR's) "Quarterly Monitoring Report - December 1995" dated February 5, 1996 This document presents analytical results and field observations collected during Fourth Quarter 1995 groundwater sampling activities For your convenience a summary of previous site activities is attached Fourth Quarter 1995 Groundwater Sampling Results- December 1995 On December 19, 1995, samples were collected from each of the groundwater monitoring wells (MW-1 through MW-4) at the subject site by a representative of SECOR 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 southeasterly flow at a rate of 0 001 ft Ift was encountered in the wells at depths of 73 42 feet to 85 19 feet below ground surface The location of the wells is identified on Figure 2 of the attached report Since the previous sampling event, groundwater elevation increased in MW-1, MW-3, and MW-4 by 0 40 feet to 0 69 feet, while it fell in MW-2 by 3 3 feet The changes in groundwater levels resulted in an overall average decrease in groundwater elevation of 0 44 feet across the site Groundwater flow direction remained consistent with previously collected data, however, gradient decreased somewhat The variations in groundwater elevation and gradient are most likely due to seasonal variation Table 1 in the attached report summarizes all groundwater elevation data collected to date Analyses identified 3,400 ppb gasoline, 200 ppb benzene, 850 ppb toluene, 120 ppb ethylbenzene, and 560 ppb xylenes in the sample collected from MW-1(located nearest to the existing pump islands) The sample collected from MW-3, located to the southeast of the former tank bed (downgradient), contained 1,800 ppb gasoline, 140 ppb benzene, 180 ppb toluene, 78 ppb ethylbenzene, and 260 ppb xylenes, and the sample collected from MW-4, located to the southwest of the former tank bed (sidegradient), contained 410 ppb gasoline, 65 ppb benzene, 3 6 ppb toluene, 28 ppb ethylbenzene, and 4 1 ppb