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L & M OPERABLE UNIT - THIRD QUARTER 2013 SITE STATUS, REMEDIAL SUMMARY, <br /> AND GROUNDWATER MONITORING REPORT <br /> Appendix B <br /> Page 2 <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, 313-1, 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-Sorber® 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, following the <br /> installation of seven DPE wells (DPE-1 though DPE-7). SPH were reportedly present in wells <br /> DPE-1, DPE-3, DPE-4, DPE-6, and DPE-7 prior to the initiation of testing. DPE tests were <br /> performed utilizing well 2AMW-14 for approximately 45 hours; simultaneously on wells DPE-4 <br /> and DPE-6 for approximately 28 hours; and simultaneously on wells DPE-1, DPE-3, and DPE-7 <br /> for approximately 26 hours. Results of DPE feasibility testing indicated the following: (1) a <br /> calculated radius of influence of 31 ft west of well 2AMW-14, and lower estimated radii of <br /> influence to the south and east due to the presence of low permeability clays and lower induced <br /> vacuum readings in wells DPE-3, DPE-4, and DPE-7; and (2) the removal of an estimated <br /> 196.38 pounds (lbs.) of total petroleum hydrocarbons in gasoline range organics (TPHg) from <br /> soil and groundwater, 97.02 lbs. of total petroleum hydrocarbons in diesel range organics <br /> 5ta ntec <br />