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On July 18, 1995, Smith Technology supervised the installation of three groundwater monitoring
<br /> wells, MW-1, MW-2, and MW-3 (Figure 2). During installation of the monitoring wells, soil
<br /> samples were collected from the borings. On July 21, 1995, Smith Technology developed and
<br /> sampled monitoring wells MW-1, MW-2 and MW-3. Analytical results of the soil and
<br /> groundwater samples collected indicated elevated concentrations of petroleum hydrocarbons were
<br /> present in the soil and groundwater downgradient of the former gasoline UST locations.
<br /> On September 24 and October 2, 1996, Smith Technology conducted an additional subsurface
<br /> investigation at the site. A total of nine soil borings were advanced to depths up to 15 feet below
<br /> ground surface. Soil, soil vapor, and groundwater samples were collected from the borings.
<br /> Analytical results of the soil and groundwater samples indicated the general extent of total
<br /> petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, ethylbenzene, and xylenes
<br /> (BTEX), and methyl tertiary butyl ether (MTBE) in soil and groundwater under the site.
<br /> Analytical results for geochemical parameters in soil and groundwater indicated bioremediation is
<br /> occurring in the plume of petroleum hydrocarbons in groundwater beneath the site. Analytical
<br /> 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 on soil samples from
<br /> the site indicated that the potential receptor on-site, the water supply well, would not be affected
<br /> by the plume of petroleum hydrocarbons in groundwater within the next 20 years, in the worst
<br /> case.
<br /> On March 9, 1999, ATC supervised the installation of three groundwater monitoring wells, MW-
<br /> 4, MW-5, and MW-6 (Figure 2). During installation of the monitoring wells, soil samples were
<br /> collected from the borings. On March 11, 1999, ATC developed and sampled monitoring wells
<br /> MW-4, MW-5, and MW-6. Analytical results of the soil and groundwater samples collected at
<br /> the site indicated the lateral extent of impacted soil and groundwater had been defined. Refer to
<br /> ATC's Summary Report Additional Subsurface Investigation, 7675 West Eleventh Street, Tracy,
<br /> California, dated May 12, 1999, for additional information.
<br /> Based on historical data and a verbal discussion with Mr. Ron Rowe of SJEHD, ATC submitted a
<br /> closure report request dated June 27, 2000. SJEHD did not formally respond to the report but
<br /> instead requested that ATC perform another monitoring event. In a letter dated October 2, 2001,
<br /> Ms. Dot Lofstom of the SJEHD requested computer modeling of the groundwater plume be
<br /> conducted. ATC evaluated contaminant migration potential of affected soil and groundwater at
<br /> the site using the EPA's BIOSCREEN (v.1.4) software program. The results of the computer
<br /> modeling indicated the petroleum impacted soil and groundwater at the site do not appear to be
<br /> an immediate and significant threat to human health or the environment. The computer modeling
<br /> results are presented in ATC's Addendum to Additional Site Evaluation and Request for No
<br /> Further Action far Fayette Manufacturing Corporation, dated November 4, 2002.
<br /> On April 5 and 8, 2004 an additional subsurface investigation consisting of three geoprobes
<br /> (GP-1, GP-2 and GP-3) and one cone penetrometer (CPT-1) were advanced to evaluate the
<br /> s:\Environmental\17861\reports\1gmr2004.doc 2 ATC Associates Inc.
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