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Site Background Information
<br /> Eckert Cold Storage,Manteca,CA
<br /> July 2,2003
<br /> Page 2 of 3
<br /> depth to water measurements indicate the groundwater gradient was generally towards the west on June
<br /> 26, 2002. The groundwater gradient estimated with MW-3, MW-4, and MW-6 was 0.0011 ft./ft. towards
<br /> the northwest. Historical groundwater data collected by WHY indicates a highly variable gradient at the
<br /> site. Upon review of historical groundwater gradient information provided by WHF, Condor agrees that
<br /> the general historical groundwater gradient is predominantly towards the northwest at the site. The highly
<br /> variable gradient at the site may be related to domestic/supply well pumping both on-and off-site. In
<br /> addition, when the water table slope has been very flat, and any slight variability in groundwater
<br /> measurements and the tolerance for error for the water level measurement devices can result in apparent
<br /> groundwater elevation contours that are not particularly coherent.
<br /> At the direction of the SJCEHD, Condor prepared and submitted a Problem Assessment Work Plan
<br /> (PAWP) for the site, dated May 31, 2002. Mr. Harlin Knoll of the SJCEHD approved the PAWP in a
<br /> letter dated July 11, 2002. Condor subsequently prepared a UST Fund cost pre-approval request dated
<br /> July 29, 2002, for the scope of work described by the PAWP.
<br /> Quarterly sampling of Total Petroleum Hydrocarbons quantified as Diesel (TPH-D) was discontinued
<br /> during the third quarter 2002. Condor documented approval by the SJCEHD regarding discontinuation of
<br /> TPH-D as a quarterly monitored analyte in a letter to Mr. Knoll dated September 26, 2002. SJCEHD
<br /> approval was based on historical data indicating that the presence of TPH-D in site groundwater has been
<br /> sporadic, very low in concentration, and likely the result of weathered gasoline rather than from the
<br /> possible presence of diesel in the source area.
<br /> Condor conducted the third quarter 2002 groundwater monitoring event at the site on September 30,
<br /> 2002. Groundwater samples were collected and submitted for laboratory analyses from monitor wells,
<br /> MW-1, MW-3, MW-4, MW-5, MW-6, MW-7, MW-8, and domestic well DW-1. No separate phase
<br /> petroleum was noted in the groundwater recovered from the wells, but a strong petroleum odor was noted
<br /> 'n.MW-1, MW-3, and MW-8 and a very slight "earthy" odor was noted in MW-7. A slight sheen was
<br /> observed in the groundwater purged from MW-1. The groundwater samples collected from the monitor
<br /> wells and the domestic well were analyzed for BTEX, THP-G, and selected gasoline oxygenates/additives
<br /> including MTBE by Argon Laboratories of Ceres, California. Laboratory analytical results for the
<br /> September 30, 2002, monitoring event were generally consistent with historical laboratory analytical
<br /> results.
<br /> The average groundwater elevation was approximately 1.71 feet lower on September 30, 2002 than the
<br /> previous sampling event conducted on June 26, 2002. The groundwater elevation contours estimated with
<br /> the depth to water measurements indicated the groundwater gradient was generally towards the west on
<br /> September 30, 2002. The groundwater gradient estimated using MW-4, MW-6, and MW-7 was 0.0013
<br /> ft./ft. towards the northwest, and was generally consistent with historical groundwater gradients estimated
<br /> for the site.
<br /> On October 10 and 11, 2002, Condor conducted the additional groundwater investigation activities
<br /> described by the PAWP at the Eckert Cold Storage facility using direct push boring methods [Cone-
<br /> Penetrometer (CPT) and Hydropunch] in order to satisfy SJCEHD requirements to further investigate the
<br /> lateral and vertical extent of groundwater contamination at the site. Condor supervised the installation of
<br /> ten shallow direct push (hydropunch) borings and two deep direct push (CPT) boring pairs (four CPT .
<br /> borings total). Condor prepared a Problem Assessment Report (PAR) dated November 25, 2002,
<br /> describing the results of the additional groundwater investigation.
<br /> Condor conducted the fourth quarter 2002 groundwater monitoring event at the site on December 9, 2002.
<br /> Groundwater samples were collected and submitted for laboratory analyses from monitor wells, MW-1,
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