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Graundwatcr clavation contours for June, 21 2000 indicated that the groundwater gradient at the site was
<br /> generally consistent with the historical groundwater gradient
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<br /> I On September 7, 2000 C ondor conducted quarterly groundwater and surface water monitoring at the site
<br /> Laboratory analytical result,, of the groundwater tramples collected during the third quarter, 2000, monitoring
<br /> event were generally consistent with historical quarterly groundwater analytical data During the September 7,
<br /> 2000, monitoring event, m CBE was detected at low concentrations in surface water samples DDN (1 7 pg/l ) and
<br /> IDCW (10 lig/L) -1 lie concentration of MTBE in surface water sample IDCW represented an historical high for
<br /> that sample location through the September 7, 2000, monitoring event
<br /> Groundwater elevation measurements collected at the site on September 7, 2000, indicated that the average depth
<br /> to groundwater was approximately 6 4 feet bLIow the monitor well and water surface measuring points
<br /> Groundwater elevation contours for September 7, 2000, indicated that the groundwater gradient at the site was
<br /> generally consistent with the historical groundwater gradient
<br /> I In a letter dated June 30, 2000, Mr Rowe of the San Joaquin County PHS/FI1D directed the submittal of a work
<br /> plan amendment to modify the scope of work proposed in the above referenced work plan and work plan
<br /> addendum According to Mr Rowe, the work plan amendment was to describe vertical characterization of the
<br /> potential MTBh plume and be submitted by August 1, 2000 Condor subsequently prepared the Status Report
<br /> and Addendum to the Work Plan, dated July 24, 2000 Mr Rowe approved the work plan amendment in a faxed
<br /> message, dated August 3, 2000 In a telephone conversation with Mr Rowe on August 3, 2000, Condor
<br /> I requested that the submittal date for the report of findings be extended to October 6, 2000 Mr Rowe verbally
<br /> concurred with the extension and requested that Condor prepare a letter to document the conversation Condor
<br /> followed up with a letter dated August 3, 2000
<br /> IThe installation and sampling of the soil borings described by thL Work Plan, Work Plan Addendum, and Work
<br /> Plan Amendment were conducted at the site between September I I and 13, 2000 i he results of the
<br /> investigation were described in the Soil and Groundwater Investigation and Sensitive Receptor Survey Report,
<br /> dated October 2, 2000 Direct push (Geoprobe), hand auger, and hollow-stem auger techniques were used to
<br /> advance 13 borings at the site (Borings DP-1 through DP-9, SP-1, and HP-1 through HP-3) Sod sampling was
<br /> conducted with direct push coring or Simulprobe techniques, as necessary Groundwater sampling was
<br /> conducted with the direct push groundwater sampling tool (hydropunch style) The purpose of the work was to
<br /> further investigate the extent of petroleum hydrocarbon contamination in the east portion of the site and the
<br /> property(agricultural field) adjacent to the east portion of the site
<br /> Laboratory analytical results indicated that MTBE was present in the soil samples collected at approximately 4
<br /> feet bgs from DP-4 and at approximately 8 feet bgs from DP-5 at concentrations of 1,600 and 7,100 µg/Kg,
<br /> respectively TAME was also present in the soil sample collected at approximately 8 feet bgs from DP-5 at a
<br /> concentration of 180 µg/Kg None of the analytes of interest were detected at or above the laboratory reported
<br /> detection limits in any of the soil samples collected from DP-3, DP-6, DP-7, DP-8
<br /> Laboratory analytical results of the groundwater samples indicated that an elevated concentration of MTBE
<br /> (37,000 µg/1) was present in the shallow groundwater at the location of DP-5 Benzene, ethyl benzene, total
<br /> xylenes, TPH-G, and TAME were also present at that location at concentrations of 330 }ig/L, 80 gg/L, 110 µg/L,
<br /> 1 7 mg/L, and 130 pg/L, respectively TPIi-G was present at a concentration of 0 28 mg/l in the gioundwatei
<br /> sample collected at approximately 24 feet bgs from HP-1 With the exception of these two groundwater samples,
<br /> none of the analytes of interest, other than MTBE, were detected in any of the other groundwater samples at or
<br /> above the laboratory reported detection limits Trace to moderate concentrations of MTBE, ranging from 2 2 to
<br /> • 181 jig/L, were detected in shallow groundwater samples collected from DP-1, DP-2, DP-3, DP-4, DP-6, DP-8,
<br /> and DP-9 With the exception of a concentration of 5 4 µg/L in the groundwater sample collected from
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