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Site History
<br /> Boyett Petroleum(419 S.Main St.,Manteca)
<br /> Page 5 of I l
<br /> collected on March 21, 2003, generally indicated a groundwater flow direction to the west/southwest, a
<br /> reversal from that reported in the Fourth Quarter Monitoring Report December 2002, dated February 12,
<br />' 2003.
<br /> In the First Quarter Groundwater Monitoring Report, March 2003 Condor recommended the preparation
<br />' of a problem assessment work plan (PAWP) to further investigate the lateral and vertical extent of
<br /> groundwater contamination at the site; and the completion of a door-to-door survey of potential receptors
<br /> within the residential area of the site to attempt to identify the presence of pumping wells in the site
<br />' vicinity.
<br /> On May 15, 2003, a meeting was held at the SJCEHD offices between Condor and SJCEHD
<br /> representatives to discuss Condor's recommendations and address concerns the SJCEHD had regarding
<br /> the site. In a letter dated May 29, 2003, the SJCEHD directed the submittal of two individual work plans
<br /> to install, test, and operate an interim remediation system and to adequately define the lateral and vertical
<br /> extent of the contamination plume at the site. The SJCEHD agreed with Condor's recommendations to (1)
<br /> conduct a door-to-door survey of potential receptors, (2) redevelop MW-1, MW-2, MW-3, MW-6, MW-
<br /> 7,MW-8, and MW-9, (3) destroy both damaged and consistently dry wells MW-4 and MW-5, and replace
<br /> MW-4 with a new monitoring well in the same area, and (5) conduct a monthly monitoring and sampling
<br />' schedule over a consecutive six month period to characterize the fluctuation of MTBE concentrations in
<br /> groundwater. In addition, the SJCEHD recommended that the design of MW-1 be reviewed within the
<br /> context of a site conceptual model to determine if MW-1 potentially creates a vertical conduit between
<br />' lithologic units and to submit a work plan for well replacement if appropriate.
<br /> On June 25, 2003, a Condor representative was on site to measure water levels and collect groundwater
<br /> . samples at monitoring wells MW-1, MW-2, MW-3, MW-6, MW-7, MW-8, and MW-9. Monitoring wells
<br /> MW-4 and MW-5 are damaged and slated for destruction; as a result, water level measurements and
<br /> groundwater samples were not collected from these two monitoring wells. Laboratory analytical results
<br /> for the groundwater samples collected at the site on June 25, 2003, indicated that BTEX constituents and
<br /> TPH-G were not detected at or above the laboratory reported detection limits in any of the groundwater
<br /> samples collected from the monitoring wells. Gasoline oxygenates/additives were not detected at or above
<br /> the laboratory reported detection limits in the groundwater samples collected from MW-3, MW-6, MW-8
<br />' and MW-9. MTBE was detected in the groundwater samples collected from MW-1, MW-2, and MW-7.
<br /> TAME was detected in the groundwater samples collected from MW-1 and MW-7. Static water level
<br /> measurements generally indicated a groundwater gradient of 0.0085 ft/ft towards the southwest.
<br />' At the direction of the SJCEHD, Condor submitted an Additional Groundwater Investigation Work Plan,
<br /> dated June 25, 2003, and an Interim Remediation Work Plan, dated June 25, 2003, to the SJCEHD and
<br />' CRWQCB. The Additional Groundwater Investigation Work Plan was prepared to describe proposed
<br /> groundwater investigation activities to evaluate the lateral and vertical extent of petroleum hydrocarbon
<br /> contamination in groundwater up-gradient and down-gradient of the UST area using direct push boring
<br />' methods. The Interim Remediation Work Plan addressed the installation of a pump and treat system for
<br /> interim remediation, and the destruction of MW-4 and MW-5 and the installation of a replacement
<br /> monitoring well for MW-4. In two letters dated August 25, 2003, Mr. Jeffrey Wong of the SJCEHD
<br /> approved both work plans.
<br />' Condor conducted a SRS within an approximate 500-foot radius of the site on July 12, 2003, to identify
<br /> potential water wells and potential sources of pumping influences on the groundwater at the site.The SRS
<br /> consisted of door-to-door inquiries/interviews and visual inspection of the residential area that is within
<br /> • approximately 500 feet of the site.A site reconnaissance within the residential area of the site vicinity was
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