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<br /> detailed in Smith Technology Corporation's Problem Assessment Report, Fayette Manufacturing
<br /> Corporation, 7675 West Eleventh Street, Tracy, California, dated November 7, 1995.
<br /> On September 24 and October 2, 1996, Smith Technology supervised the advancement of nine
<br /> soil borings, SB-1 through SB-7 and FPB-1 and FPB-2 at the locations shown on Figure 2. The
<br /> borings were advanced utilizing direct push technology and soil, soil vapor, and groundwater
<br /> samples were collected for chemical analyses. Visual observation of free product was noted in
<br /> borings FPB-2 and SB2. Analytical results of the soil, soil vapor, and groundwater samples
<br /> 60 collected delineated the horizontal extent of petroleum hydrocarbon contamination in the vicinity
<br /> of the former gasoline UST locations.
<br /> During this phase of work,the collected soil, grab groundwater, and soil vapor samples were also
<br /> submitted for geophysical analysis to determine if natural biodegradation of petroleum
<br /> constituents was occurring beneath the site. Soil samples from significantly different lithological
<br /> units encountered during drilling were submitted for the following geophysical analyses: falling
<br /> head permeability, percent moisture, porosity, dry bulk density, soil pH, percent organic content,
<br /> and carbon to nitrogen to phosphorus (C:N:P) ratios. Grab groundwater samples were field
<br /> monitored for oxidation-reduction potential and submitted for laboratory analysis of carbon
<br /> dioxide, alkalinity, nitrate, sulfate, and ferrous iron. Soil vapor samples were submitted for
<br /> laboratory analysis of oxygen, carbon dioxide, nitrogen, and methane. This phase of work is
<br /> detailed in Smith Technology Corporation's Additional Soil and Groundwater Report, Fayette
<br /> Manufacturing Corporation, 7675 West Eleventh Street, Tracy, California, dated January 31,
<br /> 1997.
<br /> Between September 1996 and June 1997, natural attenuation monitoring was performed on
<br /> samples from each site groundwater well as well as on grab groundwater samples collected from
<br /> soil borings. Based upon geotechnical and geochemical data collected from groundwater, the
<br /> study concluded that intrinsic bioremediation may be taking place in the contaminant plume
<br /> beneath the site. In ATC's Problem Assessment Report & Corrective Action Plan, dated April 1,
<br /> 1998, the natural attenuation monitoring performed at the site was discussed in detail and
<br /> presented as the recommended corrective action for the site.
<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 EHD, ATC submitted a
<br /> closure report request dated June 27, 2000. EHD 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 Lofstrom of the EHD requested computer modeling of the groundwater plume be
<br /> sA17861\reports\sum2004.doc 2
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