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PHONE 206-285 2400
<br /> CABLE ADDRESS TUOIL
<br /> SEATTLE T _ _ ,(FAX),206-283-8036
<br /> TACOMA N 1
<br /> PORTLAND T
<br /> STOCKTON
<br /> LOS ANGEDLES 3 RENO V I2 23 "E TIME O I L CON i i0 7
<br /> 8 4 F �
<br /> 7 6 5 TS 2737 WEST COMMODORE WAY SEATTLE,WASHINGTON 98199 1233
<br /> PRODUCTS T. P O BOX 24447,TERMINAL STATION SEATTLE, WASHINGTON 98124 0447
<br /> TIME TEST Ep
<br /> iA February 2, 1998
<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 1997 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 (PHSIEHD),
<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 /> - December 1997" dated January 2B, 1998 This document presents analytical results and field observations
<br /> collected during Fourth Quarter 1997 groundwater sampling activities
<br /> For your convenience a summary of previous site activities is attached
<br /> Fourth Quarter 1997 Groundwater SamplingR sul -October 1997
<br /> On October 13, 1997, 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 which appeared to converge in the center of the site was encountered in the wells at depths of
<br /> 66 40 feet to 81 81 feet below ground surface Free product was not encountered in any of the wells The
<br /> locations of the wells are identified on Figure 2 of the attached report
<br /> Since the July 1997 sampling event, groundwater elevation decreased in MWA and MW-4 through MW-9 by
<br /> 0 34 feet to 1 14 feet, and groundwater elevation increased in MW-2, MW-3, MWA 0 by 0 25 feet, 0 42 feet,
<br /> and 0 03 feet, respectively These changes resulted in an overall average decrease in groundwater elevation
<br /> of 0 42 feet across the site Groundwater flow direction has typically been to the southwest on the subject
<br /> site, however, a convergence in groundwater flow was Indicated in the October sampling event Changes in
<br /> flow direction and gradient are most likely a result of seasonal variation Table 1 in the attached report
<br /> summarizes all groundwater elevation data collected to date
<br /> Analyses identified elevated concentrations of hydrocarbons in the samples collected from MWA (35,500
<br /> ppb gasoline, 921 ppb benzene, 5,410 ppb toluene, 1,400 ppb ethylbenzene, and 5,820 ppb xylenes), MW-2
<br /> (675 ppb gasoline, 114 ppb benzene, 16 6 ppb toluene, 2 8 ppb ethylbenzene, and 150 ppb xylenes), MW-3
<br /> (2,820 ppb gasoline, 246 ppb benzene, 72 ppb toluene, 107 ppb ethylbenzene, and 133 ppb xylenes), MW-5
<br /> (2,010 ppb gasoline, 138 ppb benzene, 221 ppb toluene, 28 4 ppb ethylbenzene, and 291 ppb xylenes), and
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