|
Stantec
<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, 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 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 />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
<br />I:\Tidewater\TW Stockton (Parcel 2A-0415)\Reports\QMR\2010\3010\3010QSSRORSROMR Stockton_FINAL.doc 1.4
<br />
|