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Boyett Petroleum,Manteca
<br /> Third Quarter 2402 Groundwater Monitoring Report
<br /> Page 2
<br /> and 140 p,g/L, respectively. Tert-butanol (TBA) was reported in MW-I at a concentration of 98 1tg/L. Tert-
<br /> amyl methyl ether (TAME) was reported in MW-1 and MW-3 at concentrations of 7.7 µg/L and 16 µg/L,
<br /> respectively. Quarterly groundwater monitoring at the site began in the fourth quarter, 1999.
<br /> WHF prepared the Lateral Extent of Groundwater Contamination Work Plan, dated May 18, 2000, describing
<br /> proposed activities associated with the installation of four additional monitoring wells intended to define the
<br /> lateral extent of groundwater contamination. At the request of the SJCEHD, WHF modified the work plan to
<br /> include use of cone penetration technology (CPT). The modified work plan was subsequently approved by the
<br /> ' SJCEHD on June 9, 2000.
<br /> On December 20-22, 2000, WHF, in conjunction with Frontier Drilling, completed four soil borings. The
<br /> borings, which vaiied in total depth between 20 and 25 feet bgs, were subsequently converted into monitoring
<br /> wells MW-5 through MW-8; groundwater depth was measured at approximately 17 feet bgs. Soil samples were
<br /> collected from each boring at five-foot intervals for soil classification and three soil samples were collected
<br /> from each boring at depth intervals of 16-16.5 feet, 20-21.5 feet, and 26-26.5 feet for laboratory analyses.
<br /> Laboratory analytical results of the twelve soil samples indicated petroleum hydrocarbons were not detected at
<br /> or above the laboratory reported detection limits.
<br /> On February 2, 2001, WHF, in conjunction with VB1 In-Situ Testing of Sacramento, California, advanced two
<br /> CPT borings at the site. CPT-I and CPT-2 were completed to depths of 76 and 76.4 feet bgs, respectively. Both
<br /> borings encountered resistance at the termination depths. WHF submitted a report of their findings of the CPT
<br /> borings in a letter to Mr. Wong of the SJCEHD dated February 7,2001.
<br /> On April 25, 2001, WHF, in conjunction with Frontier Drilling, completed a deep monitoring well, MW-9, to a
<br /> depth of 50.5 feet bgs. The screen interval for the well was placed at 40.5-50.5 feet bgs. Groundwater depth was
<br /> measured at approximately 17 feet bgs. Two soil samples were collected from the borehole at depths of 43.5
<br /> I feet and 50 feet for laboratory analyses. None of the analytes of concern (BTEX, TPH-G, and MTBE) were
<br /> detected in the soil samples collected from the borehole of MW-9. Laboratory analytical results of a
<br /> groundwater sample collected from MW-9 indicated that none of the analytes of concern (BTEX, TPH-G, and
<br /> selected gasoline oxygenates/additives) were detected, with the exception of MTBE, which was detected at a
<br /> concentration of 14 1,g/L. In the Final Report of Findings — Lateral Extent of Groundwater Contamination
<br /> dated June 29, 2001, WHF concluded that the source of the petroleum hydrocarbon contamination had not been
<br />' identified and recommended that quarterly groundwater monitoring continue, one additional monitoring well be
<br /> installed directly east of the fuel island, and that no remedial action be taken at this site until the source is
<br /> identified.
<br /> 3.0 THIRD QUARTER 2002 GROUNDWATER MONITORING
<br /> On September 26, 2002, a Condor representative was on site to measure water levels in all nine monitoring
<br /> wells and collect groundwater samples from monitoring wells MW-I through MW-9 as part of the third quarter
<br /> 2002 quarterly groundwater monitoring event. The locations of the monitoring wells are shown in Figure 2,
<br /> Appendix A.
<br /> A11 down-hole field equipment was decontaminated in the field with a solution of laboratory-grade, non-
<br /> phosphate detergent and deionized water and double rinsed with deionized water prior to use in each well. All
<br /> 1 111111 1111LI111111nits were caldillated 'toi3inllulal:ltt!'CI- i"uttlfnendeu standards. lne water leve! In each weii was
<br /> measured to the nearest 0.01 foot with a battery-operated, flat-tape, water-level meter. A new, disposable,
<br /> polyethylene bailer was lowered into the monitoring wells to collect a field-inspection sample. The bailer
<br /> samples were inspected for floating product, sheen, discoloration and odor. The monitoring wells were purged
<br /> kk4i
<br />' �a CONDOR
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