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Site History
<br /> Boyett Petroleum(419 S.Main St.,Manteca)
<br /> Page 5 of 6
<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 MWA, 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 monitor 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-I 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 in and collect groundwater
<br /> samples from monitor wells MW-1, MW-2, MW-3, MW-6, MW-7, MW-8, and MW-9. Monitor wells
<br /> MW-4 and MW-5 arc damaged and slated for destruction; as a result, water level measurements and
<br /> groundwater samples were not collected from these two monitor wells. Laboratory analytical results for
<br /> 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 monitor 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 /> monitor 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
<br /> conducted on foot and residents were contacted by knocking on residential (houses, duplexes/triplexes,
<br /> and apartments) doors and inquiring of the owner/renter. The actual and potential locations of wells were
<br /> identified either by a caretaker or by a neighbor living within the SRS area. Three well locations were
<br /> identified within the study area. No DWR well records were available for two of the three wells. During
<br /> the 2002 sensitive receptor survey for the site vicinity, a well was thought to be located at 188 W. Oak
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