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Site History
<br /> Boyett Petroleum(419 S.Main St.,Manteca)
<br /> Page 2 of 6
<br /> . 20-21.5 feet, and 26-26.5 feet for laboratory analyses. Laboratory analytical results of the twelve soil
<br /> samples indicated petroleum hydrocarbons were not detected at or above the laboratory reported detection
<br /> limits in any of the samples.
<br /> On February 2, 2001, WHF, in conjunction with VBI In-Situ Testing of Sacramento, California, advanced
<br /> two CPT borings at the site. CPT-1 and CPT-2 were completed to depths of 76 and 76.4 feet bgs,
<br /> respectively. Both borings were terminated due to refusal. WHF submitted a report of their findings of the
<br /> CPT borings in a letter dated February 7, 2001, to Mr. Jeffrey Wong of the SJCEHD.
<br /> On April 25, 2001, WHF, in conjunction with Frontier Drilling, completed a deep monitor well, MW-9,
<br /> to a depth of 50.5 feet bgs. The screen interval for the well was placed at 40.5-50.5 feet bgs. Groundwater
<br /> depth was measured at approximately 17 feet bgs. Two soil samples were collected from the borehole at
<br /> depths of 43.5 feet and 50 feet for laboratory analyses. None of the analytes of concern (BTEX, TPH-G,
<br /> and MTBE) were detected in the soil samples collected from the borehole of MW-9. Laboratory
<br /> analytical results of a groundwater sample collected from MW-9 indicated that none of the analytes of
<br /> concern (BTEX,TPH-G, and selected gasoline oxygenates/additives)were detected, with the exception of
<br /> MTBE, which was detected at a concentration of 14 pg/L. In the Final Report of Findings — Lateral
<br /> Extent of Groundwater Contamination dated June 29, 2001, WHF concluded that the source of the
<br /> petroleum hydrocarbon contamination had not been identified and recommended that quarterly
<br /> groundwater monitoring continue, one additional monitor well be installed directly east of the fuel island,
<br /> and that no remedial action be taken at this site until the source was identified.
<br /> On September 26, 2002, a representative of Condor Earth Technologies, Inc. (Condor) was onsite to
<br /> measure water levels in, and collect groundwater samples from, monitor wells MW-1 through MW-9 for
<br /> the third quarter 2002 groundwater monitoring event. Monitor wells MW-4, MW-5, and MW-6 were
<br /> heavily silted, and MW-4 and MW-5 were dry. Mr. Jeffrey Wong of the SJCEHD was onsite to observe a
<br /> portion of the field activities.
<br /> At the request of the SJCEHD, a Condor representative was onsite to redevelop monitor wells MW4,
<br /> MW-5, and MW-6 on September 27, 2002. The redevelopment procedure applied to MW-4 and MW-5
<br /> consisted of flushing the wells with potable water, and then bailing the water from the wells. The
<br /> sediment removed from the wells consisted of medium to coarse-grained, well-rounded, and well-sorted
<br /> sand. The redevelopment activities failed to significantly reduce the amount of sediment inside the well
<br /> casings; consequently, redevelopment of MW4 and MW-5 was not successful. Based on Condor's field
<br /> observations, it appeared the casings of these wells are damaged and allowing the annular sand pack to
<br /> infiltrate inside the casings. MW-6 was successfully redeveloped by removing a significant amount of the
<br /> sediment from inside the well casing. A groundwater sample was collected for laboratory analyses from
<br /> MW-6 on September 30, 2002. No floating product, sheen, or odors associated with petroleum
<br /> hydrocarbons were observed in any of the wells sampled during the third quarter 2002 quarterly
<br /> groundwater monitoring event. All of the groundwater monitor wells sampled contained a significant
<br /> amount of suspended sediment. Laboratory analytical results for the groundwater samples collected at the
<br /> site on September 26 and 30, 2002, indicated that none of the analytes of concern (BTEX, TPH-G, and
<br /> selected gasoline oxygenates/additives) were detected at or above the laboratory reported detection limits
<br /> in the groundwater samples collected from MW-3, MW-6, and MW-8. MTBE was detected in the
<br /> groundwater samples collected from MW-1, MW-2, MW-7, and MW-9. TAME was detected in the
<br /> groundwater samples collected from MW-1 and MW-7. Static water Ievel measurements collected on
<br /> September 26, 2002, generally indicated a groundwater flow direction to the south/southwest.
<br /> On September 30, 2002, Condor representatives surveyed the locations and elevations of MW-1 through
<br /> MW-9. The ,well collars of the monitor wells were surveyed relative to an established benchmark to
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