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S E C O R
<br /> Ms. Devra Lewis
<br /> April 15, 2004
<br /> Page 3
<br /> In August and September 1989, AGS conducted a soil gas survey (VP-1 through VP-14) at the
<br /> Waterfront Redevelopment Property, and subsequently installed three groundwater monitoring wells
<br /> (MW-1 through MW-3) at the Site. A water supply well survey was also performed, which confirmed
<br /> the presence of two municipal water supply wells in the vicinity of the Site. One of the municipal
<br /> water supply wells, owned by the City of Stockton and constructed in 1972, was identified
<br /> approximately 2,200 feet east of the Waterfront Redevelopment property. Another municipal water
<br /> supply well, maintained by California Water Service, was identified approximately 5,000 feet
<br /> southeast of the Site. A total of six industrial wells were located at the Fiberboard Paper Company,
<br /> approximately 2,000 feet southwest of the Site; these wells were reportedly installed between 1921
<br /> and 1954 (AGS, October 31, 1989).
<br /> In July 1990, sixteen soil borings (B-4 through B-19) were drilled by AGS to investigate the extent of
<br /> petroleum hydrocarbons beneath the Site. Four of the soil borings (B-4 through B-7) were converted
<br /> to groundwater monitoring wells (MW-4 through MW-7). Results are included in AGS' report entitled
<br /> Evaluation of Hydrocarbons in Soil and Ground Water at City of Stockton Waterfront Redevelopment
<br /> Property, West Weber Avenue and North Lincoln Street, Stockton, California, dated January 29,
<br /> 2001.
<br /> In October 1996, twenty-two additional soil borings (TR-1 through TR-22) were drilled across the site
<br /> to determine the type and assess the extent of petroleum hydrocarbons in shallow soil and in
<br /> groundwater. Four of the borings were converted to groundwater monitoring wells (MW-8 through
<br /> MW-11). Results are presented in T&R's report entitled Subsurface Investigation, South Parcel,
<br /> West Weber Avenue & North Lincoln Street, Stockton, California, dated November 8, 1996.
<br /> In January and February 1999, ERI conducted a tidal study to determine the influence of tidal
<br /> fluctuations on the direction of groundwater flow, collected additional data to evaluate concentration
<br /> trends, and collected inorganic water quality data to investigate whether natural attenuation is
<br /> occurring beneath the Site. Pressure transducers/data loggers were installed in wells MW-5, MW-8,
<br /> and MW-9 to monitor changes in water levels within the monitoring wells over a 48-hour period.
<br /> Results of the tidal study indicated that over the testing period, observed tidal changes (up to 4 feet)
<br /> had little influence on the southerly direction of groundwater flow in the monitoring wells(less than 0.1
<br /> feet). Evaluation of Site-wide data also indicated that concentrations of petroleum hydrocarbons
<br /> have generally decreased since 1996, and that natural biodegradation activity is occurring beneath
<br /> the Site. Results of this multi-phase assessment are provided in ERI'S Groundwater Monitoring and
<br /> Sampling and Tidal Influence Study Report, The Stockton Group Site, West Weber Avenue and
<br /> North Lincoln Street, Stockton, California, dated June 11, 1999.
<br /> Between August and October 1999, T&R oversaw a geophysical survey on Parcels 2A, 3, and 4,
<br /> which involved the excavation of exploratory test pits (2ATP-1 through 2ATP-5, 2BTP-1, 3TP-1
<br /> through 3TP-4, 4TP-1 through 4TP-3) to determine the location of suspected underground structures
<br /> including USTs, sumps, and pipelines. Additional soil borings were drilled (2AB-1 through 2AB-4,
<br /> 2BB-1 through 2BB-3, 313-1, 313-2, 413-1) and groundwater monitoring wells were installed (2BMW-1,
<br /> 3MW-1, 2AMW-12 through 2AMW-15) in suspected areas of contamination. A preliminary
<br /> endangerment assessment was performed on the parcels to evaluate the environmental health risk
<br /> associated with residual petroleum hydrocarbon concentrations in soil and groundwater. Details are
<br /> presented in T&R's Site Characterization Report, South Shore Parcels, Stockton, California, dated
<br /> December 13, 1999.
<br /> Stockton Parcel 2A:Work Plan for Pipeline Abandonment,Removal,and Soil Excavation and SVE Well Install
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