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ATC Associates Inc.
<br /> V 1117 Lone Palm Avenue,Suite 201
<br /> Modesto,California 95351
<br /> 209-579-2221
<br /> %T ro Fax:209-579-2225
<br /> ASS Cc I ATE S ! N C .
<br /> permanently abandoned. Soil sample locations from the 1997 UST system removal are depicted
<br /> on Figures 3 and 4.
<br /> In August 2000, John P. Cummings & Associates (JPCA) advanced one soil boring (B1) via
<br /> direct push technology at the north end of the western dispenser island. The soil boring was
<br /> advanced to 25 feet bgs before probe refusal was encountered. In September 2000, JPCA
<br /> advanced a soil boring using hollow-stem auger technology at the same location as B1 to a depth
<br /> of 53 feet bgs. Analysis of the soil and groundwater samples from the re-bored B1 indicated that
<br /> the soil samples contained detectable concentrations of MTBE and t-butanol (TBA), and the
<br /> groundwater sample contained detectable concentrations of MTBE, toluene, and total petroleum
<br /> hydrocarbons as gasoline (TPHg). f
<br /> In May 2003, GHH Engineering, Inc. (GHH) supervised the advancement of three soil borings
<br /> (SB2, SB3, and SB4) at locations shown on Figure 2. Soil samples from borings SB3 and SB4
<br /> contained detectable concentrations of MTBE. The soil samples from SB3 also contained
<br /> detectable concentrations of benzene, ethylbenzene, and xylenes. Groundwater samples collected
<br /> from SB3 and SB4 contained detectable concentrations of TPHg, total petroleum hydrocarbons
<br /> as diesel (TPHd), and MTBE. The groundwater sample from boring SB3 also contained
<br /> detectable concentrations of benzene, ethylbenzene,total xylenes, and 1,2-DCA. _
<br /> On January 12 and 13, 2004, ATC personnel supervised the advancement of three soil borings
<br /> (MW1, MW2, and MW3) to approximately 65 feet bgs at locations shown on Figure 2.
<br /> Petroleum hydrocarbon constituents were not detected in soil samples from MW1, MW2, and
<br /> MW3. Each soil boring was completed as a groundwater monitoring well.
<br /> In May 2006, ATC personnel supervised the a ftancement of six soil borings (ASB 1 through
<br /> ASB6) at the site to depths between 52 and 60 feet bgs to evaluate soil and groundwater for the
<br /> presence of petroleum hydrocarbons across the site. Groundwater depth in each boring was
<br /> measured at approximately 50 feet bgs. The soil samples collected from borings ASB 1 through
<br /> ASB6 did not contain detectable concentrations of TPHg; TPHd; benzene,toluene, ethylbenzene,
<br /> or xylenes (BTEX); MTBE; ethyl tertiary butyl ether (ETBE); di-isopropyl ether (DIPE); tertiary
<br /> amyl methyl ether (TAME); ethyl dibromide (EDB); 1,2-dichloroethane (1,2-DCA); or TBA.
<br /> The groundwater samples collected from ASB1 and AS134 through AS136 did not contain
<br /> detectable concentrations of TPHg, TPHd, BTEX, MTBE, TAME, ETBE, DIPE, TBA, EDB, or
<br /> 1,2-DCA.
<br /> The groundwater sample collected from boring ASB2 contained 1.0 microgram per liter(µg/1) of
<br /> 1,2-DCA. The groundwater sample collected from boring ASB3 contained 3.5 µg/l of MTBE
<br /> and 4.3 µg/1 of 1,2-DCA. Field activities and analytical results are detailed in ATC's Summar:
<br /> Report ofAdditiona l,Subsurface�estigation, dated January 21,2007. so
<br /> r7 V e- � +
<br /> Well Destruction Lot '°I
<br /> On January 7 and 8, 2010, ATC supervised the destruction of monitoring wells MW 1
<br /> through MW3. Wells MWI through MW3 were constructed with 2 inch diameter PVC and —
<br /> Project No.54.26874.0001
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