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<br /> (FAX)206-283.8438
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<br /> SEATTLE N '
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<br /> RICHMOND 9 3 E - -
<br /> LOS ANGELES SEATTLE,WASHINGTON 98199.1233
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<br /> 's 2737 WEST COMMODORE WAY SEATTLE,WASHINGTON 98124=0447
<br /> vreooucrs TI P.O. BOX 24447,-TERMINAL STATION - y /� TO
<br /> TIME TESTED E .� October 24, 20015 •�
<br /> l
<br /> Mr- Harlin Knoll
<br /> San Joaquin County Public Health Services ' ' -
<br /> Environmental Health Division l
<br /> P.O. Box 2009 y
<br /> Stockton, California ,95201
<br /> RE: Submittal of"Quarterly Monitoring Report, July-September 2000"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 Envirohmental Health Division.(PHS/EHD),
<br /> an environmental investigation was implemented at the subject site it December 1994 to evaluate'the extent
<br /> of hydrocarbon=impacted soils and to determine whether&.not groundwater,had been impacted. A total of
<br /> four groundwater monitoring wells were installed during,4his investigation. In July 1.996, six additional
<br /> groundwater monitoring wells were installed on and off of the subject site to assist in defining.the extent of
<br /> groundwater impacts.",,
<br /> In August and September 1999, SECOR installed a vapor extraction/air sparging system at the subject site to
<br /> �.., remediate hydrocarbon-impacted soils and groundwater. System operation began December 13, 1999.
<br /> Please find enclosed SECOR's "Quarterly Monitoring Report, July - September 2000" dated October 17,
<br /> 2000. This document presents analytical results and field observations-collected during Third Qu6rter•2000
<br /> groundwater sampling, and discusses the efficiency,of the remediation system currently in operation. .
<br /> Third Quarter 2000 Groundwater Sampling Results ' K
<br /> On August 18, 2000, samples were collected from each of the groundwater monitoring wells (MVI'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, attached report, T.
<br /> groundwater with a southwesterly flow direction and a gradient of 0.02 ft./ft, was encountered in the wells at
<br /> depths of 66.75 feet to,76.87 feet below ground sufface. Trace free product.was encountered in MW-1 (0.01
<br /> feet). The locations of the wells are identified on.Figure 2 of the attached report,
<br /> Since the June 2000 sampling event, groundwater elevation:increased MW-1 by 2.92 feet while it.decreased
<br /> I in the remainder of the wells by 0.19 feet to 1:3 feet. These changes resulted in an overall average decrease
<br /> in groundwater elevation of 0.22 feet across the'site. Changes in groundwater elevation are most likely a
<br /> result of seasonal variation. Groundwater gradient and flow direction remained consistent with previously
<br /> collected data, Table 1 in the attached report summarizes.groundwater elevation data:coliected to date.
<br /> Analyses identified elevated concentrations of hydrocarbons and/or oxygenates in the samples collected
<br /> from.MW-3 (384 ppb TPH-g, 74.2 ppb benzene, 1.4 ppb toluene, 30.6 ppb ethylbenzene, 40 ppb xylenes,
<br /> i and 2.3 ppb MTBE), MW-4 (79 ppb TPH-g, 1.0, ppb benzene, and 3.6 ppb MTBE), and MW-9 (1.1 ppb
<br /> benzene). Lower concentrations of hydrocarbons and/or oxygenates were found in the samples collected
<br /> from MW-2 (1.1 ppb MTBE), MW-5 (0.7 ppb benzene and 6.6 ppb MTBE), and MW-6 (0.5 ppb ethylbenzene
<br /> and 1.1 ppb MTBE). Hydrocarbons were not detected in the samples collected from MW-7, MW-8, and MW-
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