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WASHINGTON r
<br /> OREGON E" PHONE(206)285-2400
<br /> CALIFORNIA 12 TD 'FAX(206)283-8036
<br /> *NEVADA
<br /> IDAHO1 23 "E � � M E L L o
<br /> 9
<br /> S 4 r
<br /> e 5 9 2737 WEST COMMODORE WAY SEATTLE,WA 98199-1233 r
<br /> PRODUCTS ria PO BOX 24447 SEATTLE,WA 98124-0447
<br /> TIME TESTED E
<br /> February 1, 1999
<br /> Mr Harlin Knoll
<br /> San Joaquin County Public Health Services
<br /> Environmental Health Division
<br /> P O Box 2009
<br /> Stockton, California 95201
<br /> RE Submittal of Fourth Quarter 1998 Groundwater Monitoring Report for
<br /> Jackpot Food Mart, 14000 E Highway 88, Lockeford, California (Property No 04-049)
<br /> Dear Mr Knoll,
<br /> At the request of the San Joaquin County Public Health Services Environmental Health Division (PHS/EHD),
<br /> an additional environmental investigation was implemented at the subject site in December 1994 to evaluate
<br /> the extent of hydrocarbon-impacted soils and to determine whether or not groundwater had been impacted
<br /> A total of four groundwater monitoring wells were installed during this investigation In July 1996, six
<br /> additional groundwater monitoring wells were installed on and off of the subject site to assist in defining the
<br /> extent of groundwater impacts Based on the results of the investigations, Time Oil has Implemented
<br /> groundwater monitoring
<br /> Please find enclosed Science & Engineering Analysis Corporation's (SECOR's) "Quarterly Monitoring Report,
<br /> October - December 1998" dated January 27, 1999 This document presents analytical results and field
<br /> observations collected during Fourth Quarter 1998 groundwater sampling activities
<br /> For your convenience a summary of previous site activities is attached
<br /> s
<br /> Fourth Quarter 1998 Groodwater Sampling R I -October 1998
<br /> On October 26, 1998, samples were collected from each of the groundwater monitoring wells (MW-1 through
<br /> MW-10) at the subject site by a representative of SECOR Prior to purging, the depth to water in each well
<br /> was measured to evaluate elevation, flow direction, and gradient As noted in the attached report,
<br /> groundwater with a southerly flow direction and a gradient of 0 03 ft/ft was encountered in the wells at
<br /> depths of 64 14 feet to 76 93 feet below ground surface Free product was not encountered in any of the
<br /> wells The locations of the wells are identified on Figure 2 of the attached report
<br /> Since the August 1998 sampling event, groundwater elevation decreased in MW-8 by 0 30 feet and in MW-
<br /> 10 by 8 48 feet, while it increased in the remaining wells by 0 17 feet to 3 57 These changes resulted in an
<br /> overall decrease in groundwater elevation of 018 feet across the site Changes in groundwater elevation are
<br /> most likely a result of seasonal variation Groundwater gradient and flow direction remained consistent with
<br /> previously collected data Table 1 in the attached report summarizes all groundwater elevation data collected ,
<br /> to date
<br /> Analyses identified elevated concentrations of hydrocarbons In the samples collected from MW-1 (18,500
<br /> AD ppb gasoline, 386 ppb benzene, 2,580 ppb toluene, 1,080 ppb ethylbenzene, 2,820 ppb xylenes), MW-2
<br /> (1,910 ppb gasoline, 31 8 ppb benzene, 12 8 ppb toluene, 2 0 ppb ethylbenzene, and 274 ppb xylenes), MW-
<br /> 3 (838 ppb gasoline, 126 ppb benzene, 17 0 ppb toluene, 47 6 ppb ethylbenzene, and 77 8 ppb xylenes),
<br /> MW-4 (901 ppb gasoline, 187 ppb benzene, 4 7 ppb toluene, 84 4 ppb ethylbenzene, 7 2 ppb xylenes), MW-
<br /> 5 (5,600 ppb gasoline, 430 ppb benzene, 279 ppb toluene, 211 ppb ethylbenzene, and 1,130 ppb xylenes),
<br />
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