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<br /> ' L & M OPERABLE UNIT-THIRD QUARTER 2010 SITE STATUS, REMEDIAL SUMMARY,
<br /> AND GROUNDWATER MONITORING REPORT
<br /> Introduction
<br /> October 27, 2010
<br /> Between August and October 1999, T&R oversaw a geophysical survey on Parcels 2A, 3, and
<br /> ' 4, which involved the excavation of exploratory test pits (2ATP-1 through 2ATP-5, 2BTP-1,
<br /> 3TP-1 through 3TP-4, 4TP-1 through 4TP-3) to determine the location of suspected
<br /> underground structures including underground storage tanks (USTs), sumps, and pipelines.
<br /> ' Additional soil borings were drilled (2AB-1 through 2AB-4, 2BB-1 through 2BB-3, 3B-1, 313-2,
<br /> and 413-1) and groundwater monitoring wells were installed (2BMW-1, 3MW-1, and 2AMW-12
<br /> through 2AMW-15) in suspected areas of contamination. A preliminary endangerment
<br /> ' assessment was performed on the parcels to evaluate the environmental health risk associated
<br /> 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,
<br /> ' dated December 13, 1999.
<br /> In 2001, additional assessment activities were conducted by T&R in the vicinity of the Site within
<br /> ' Parcel 3. Results are included in T&R's report entitled Subsurface Investigation for Area 3,
<br /> dated August 17, 2001.
<br /> ' In September 2001, a total of 11 Cone Penetrometer Test (CPT) borings (DP-1 through DP-11)
<br /> were drilled to investigate the following: (1) subsurface lithology; (2) the presence of SPH; (3)
<br /> the lateral extent of petroleum hydrocarbon impacted groundwater east, south, and west of the
<br /> ' Site; and (4) to investigate potential off-site sources upgradient (north-northwest) of the Site.
<br /> Surficial soil samples were also collected from depths up to 5 ft below ground surface (bgs) to
<br /> evaluate whether the presence of residual concentrations of metals present a threat to
<br /> ' groundwater quality. Results are presented in the Clayton Group Associates (Clayton) report
<br /> entitled Further Characterization at the West Weber Avenue and North Lincoln Street Site,
<br /> Parcel 2A, dated December 18, 2001.
<br /> In May 2002, Clayton initiated quarterly monitoring activities, installed eight additional CPT soil
<br /> borings (DP-12 through DP-19), and collected grab samples to delineate soil and groundwater
<br /> ' impacts previously identified in the vicinity of borings DP-1 through DP-6. In addition, Clayton
<br /> performed a soil gas survey in July 2002 involving the installation of 111 Gore-SorberO modules
<br /> ' to investigate the areas of greater petroleum hydrocarbon impact. Results are summarized in
<br /> Clayton's Site Delineation Report, dated August 6, 2002.
<br /> ' In December 2002, a 5-day DPE feasibility test was performed by SECOR International
<br /> Incorporated (SECOR), following the installation of seven DPE wells (DPE-1 though DPE-7).
<br /> SPH were reportedly present in wells DPE-1, DPE-3, DPE-4, DPE-6, and DPE-7 prior to the
<br /> t initiation of testing. DPE tests were performed utilizing well 2AMW-14 for approximately
<br /> 45 hours; simultaneously on wells DPE-4 and DPE-6 for approximately 28 hours; and
<br /> simultaneously on wells DPE-1, DPE-3, and DPE-7 for approximately 26 hours. Results of DPE
<br /> ' feasibility testing indicated the following: (1) a calculated radius of influence of 31 ft west of well
<br /> 2AMW-14, and lower estimated radii of influence to the south and east due to the presence of
<br /> low permeability clays and lower induced vacuum readings in wells DPE-3, DPE-4, and DPE-7;
<br /> ' and (2)the removal of an estimated 196.38 pounds of total petroleum hydrocarbons in gasoline
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