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<br /> VnS O C I A T E 5I N C j
<br /> 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 /> r= 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 /> 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 /> =r detailed in Smith Technology Corporation's Additional Soil and Groundwater Report, Fayette
<br /> r. 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
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<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 /> r; presented as the recommended corrective action for the site.
<br /> 2.0 METHODS AND PROCEDURES
<br /> To evaluate the extent of impacted soil and groundwater northwest of the former USTs, three soil
<br /> borings were advanced at the site and completed as groundwater monitoring wells. All field
<br /> r_ activities were performed in accordance with ATC's Workplan for Additional Subsurface
<br /> F7 Investigation at Fayette Manufacturing Corporation Site, 7675 West Eleventh Street, Tracy,
<br /> California, dated January 18, 1999. This workplan was approved by PHS/EHD on January 27,
<br /> 1999.
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