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Site History
<br /> Boyett Petroleum(419 S.Main St.,Manteca)
<br /> Page 1 I of 12
<br /> On June 30, 2005, a Condor representative was on site to measure water levels and collect groundwater
<br /> samples from monitoring wells MW-2, MW-3, MW-4R, MW-6 through MWA 1, and EW-1. Laboratory
<br /> analytical results indicated that BTEX constituents, gasoline oxygenates/additives other than MTBE, and
<br /> TPR-G were not detected at or above the laboratory reported detection limits in the groundwater samples
<br /> collected from the monitoring wells. MTBE was detected in the groundwater samples collected from
<br /> MW-9 and MW-11 at concentrations below the California Department of Health Services Maximum
<br /> Contaminant Level (MCL) of 13 µg/L. MTBE was not detected at or above the laboratory reported
<br /> detection limit of 0.5 µg/L in the groundwater samples collected from MW-2, MW-3, MW-4R, MW-6,
<br /> MW-7, MW-8, MW-10, and EW-1. Groundwater elevations decreased by 0.34 feet relative to the
<br /> previous monitoring event (March 2005). Groundwater elevation contours based on the depth to water
<br /> measurements collected on June 30, 2005, indicated there was a small groundwater mound near the
<br /> northeast corner of the site. The groundwater gradient at the site was to the south, west, and northwest,
<br /> away from the groundwater mound. In the Second Quarter 2005 Groundwater Monitoring Report dated
<br /> August 7, 2005, Condor recommended the site be considered for closure.
<br /> Condor prepared the No Further Action Request (NFAR) dated October 7, 2005. The NFAR was
<br /> submitted to the SJCEHD and the CRWQCB for consideration.
<br /> On September 30, 2005, a Condor representative was on site to measure water levels and collect
<br /> groundwater samples from monitoring wells MW-2, MW-3, MW-4R, MW-6 through MWA 1, and EW-1.
<br /> Laboratory analytical results indicated that BTEX constituents, gasoline oxygenates/additives other than
<br /> MTBE, and TPH-G were not detected at or above the laboratory reported detection limits in the
<br /> groundwater samples collected from the monitoring wells. MTBE was detected in the groundwater
<br /> samples collected from MW-9 and MW-11 at concentrations below the MCL of 13 µg/L. MTBE was not
<br /> detected at or above the laboratory reported detection limit of 0.5 ptg/L in the groundwater samples
<br /> collected from MW-2, MW-3, MW-4R, MW-6, MW-7, MW-8, MW-10, and EW-1. Groundwater
<br /> elevations decreased by 0.87 feet relative to the previous monitoring event (June 2005). Groundwater
<br /> elevation contours based on the depth to water measurements collected on September 30, 2005, indicated
<br /> the groundwater gradient was to the southwest.
<br /> On December 28, 2005, a Condor representative was on site to measure water levels and collect
<br /> groundwater samples from monitoring wells MW-2, MW-3, MW-4R, MW-6 through MW-11, and EW-1.
<br /> Laboratory analytical results indicated that BTEX constituents, gasoline oxygenates/additives other than
<br /> MTBE, and TPH-G were not detected at or above the laboratory reported detection limits in the
<br /> groundwater samples collected from the monitoring wells. MTBE was detected in the groundwater
<br /> samples collected from MW-9, MW-10, MW-11, and EW-1. MTBE was not detected at or above the
<br /> laboratory reported detection limit of 0.5 µg/L in the groundwater samples collected from MW-2, MW-3,
<br /> MW-4R, MW-6, MW-7, and MW-8. Groundwater elevations increased by 1.60 feet relative to the
<br /> previous monitoring event (September 2005). Groundwater elevation contours based on the depth to
<br /> water measurements collected on December 28, 2005, indicated the groundwater gradient was to the
<br /> north.
<br /> In a letter dated April 14, 2006, Jeffrey Wong of the SJCEHD described the results of a discussion with
<br /> the CRWQCB with regards to the NFAR dated October 7, 2005. Mr. Wong stated the SJCEHD and the
<br /> CRWQCB agreed that the site is not quite ready for closure. Mr. Wong requested a work plan to complete
<br /> the lateral definition of the dissolved MTBE plume toward the northwest, to provide a fate-and-transport
<br /> model showing the path of travel of the plume before it reaches background levels. and to discuss and
<br /> evaluate the risk of soil vapor intrusion into all nearby structures. Healsorecommended conducting a
<br /> limited batch groundwater extraction at monitoring wells MW-11 and EW-11 since the MTBE
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