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<br /> On September 24 and October 2, 1996, Smith Technology conducted an additional subsurface investigation
<br /> at the site. A total of nine soil borings were advanced to depths up to 15 feet below ground surface. Soil,
<br /> soil vapor, and groundwater samples were collected from the borings. Analytical results of the soil and
<br /> groundwater samples indicated the general extent of total petroleum hydrocarbons as gasoline (TPHg),
<br /> benzene, toluene, ethylbenzene, and xylenes (BTEX), and methyl tertiary butyl ether (MTBE) in soil and
<br /> groundwater under the site. Analytical results for geochemical parameters in soil and groundwater indicated
<br /> bioremediation is occurring in the plume of petroleum hydrocarbons in groundwater beneath the site.
<br /> Analytical results of soil vapor samples indicated the availability of oxygen, carbon dioxide, nitrogen and
<br /> methane in the vadose zone. Also, results of laboratory geophysical testing of soil samples from the site
<br /> indicated that the potential receptor on-site, the water supply well, would not be affected by the plume of
<br /> petroleum hydrocarbons in groundwater within the next 20 years, in the worst case.
<br /> On March 9, 1999, ATC supervised the installation of three groundwater monitoring wells, MW-4, MW-5,
<br /> and MW-6 (Figure 2). During installation of the monitoring wells, soil samples were collected from the
<br /> borings. On March 11, 1999, ATC developed and sampled monitoring wells MW-4, MW-5, and MW-6.
<br /> Analytical results of the soil and groundwater samples collected at the site indicated the lateral extent of
<br /> impacted soil and groundwater had been defined. Refer to ATC's Summary Report Additional Subsurface
<br /> Investigation, 7675 West Eleventh Street, Tracy, California, dated May 12, 1999,for additional information.
<br /> Based on historical data and a verbal discussion with Mr. Ron Rowe of the SJCEHD, ATC submitted a
<br /> closure report request dated June 27, 2000. The SJCEHD did not formally respond to the report but instead
<br /> requested that ATC perform another monitoring event. In a letter dated October 2,2001,Ms. Dot Lofstom of
<br /> the SJCEHD requested computer modeling of the groundwater plume be conducted. ATC evaluated
<br /> contaminant migration potential of affected soil and groundwater at the site using the EPA's BIOSCREEN
<br /> (v.1.4) software program. The results of the computer modeling indicated the petroleum impacted soil and
<br /> groundwater at the site do not appear to be an immediate and significant threat to human health or the
<br /> environment. The computer modeling results are presented in ATC's Addendum to Additional Site
<br /> Evaluation and Request for No Further Action for Fayette Manufacturing Corporation, dated November 4,
<br /> 2002.
<br /> On April 5 and 8, 2004, an additional subsurface investigation consisting of three Geoprobe soil borings
<br /> (GP-1, GP-2 and GP-3) and one cone penetrometer test boring (CPT-1) was conducted to evaluate the
<br /> vertical extent of impacted soil in the vicinity of the former USTs and possible lateral migration of
<br /> impacted groundwater between wells MW-4 and MW-5. The results were submitted in a Summary Report
<br /> on Additional Subsurface Investigation, dated August 11, 2004.
<br /> On January 10 and 17, 2005, ATC supervised the installation of two groundwater monitoring wells (MW-7
<br /> and MW-8). The wells were installed hydraulically downgradient with respect to the locations of the former
<br /> USTs and are the most northerly monitoring wells at the site. A low concentration of xylenes in the
<br /> groundwater sample collected from MW-7 was the only analyte of interest detected in groundwater samples
<br /> collected from these wells on January 26, 2005. Refer to ATC's First Quarter 2005 Groundwater
<br /> Monitoring Event and Well Installation Report, dated April 20, 2005, for additional information.
<br /> s:\Environmental117861\reportst3gmr2005.doc 2 ATC Associates Inc.
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