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Work Plan For Additional Groundwater Assessment
<br /> Ranch Market,23569 South Santa Fe Road.Riverbank,California 4
<br /> May 10.2001
<br /> Water samples collected from domestic wells have been analyzed for the presence of BTEX,
<br /> TPHg, five oxygenates, 1,2-Dichloroethane (1,2-DCA), and 1,2-Dibromoethane (EDB). Since
<br /> water samples collected from DW-2 contained reportable concentrations of MtBE, the well was
<br /> taken out of service.
<br /> On April 6, 2000, SECOR's field technician interviewed the property owners or renters
<br /> associated with the four domestic water wells and found that water pumped from wells DW-1,
<br /> DW-3, and DW-4 was used for irrigation and domestic use. All parties interviewed indicated
<br /> they were drinking bottled water.
<br /> Replacement of Domestic Well DW-2
<br /> On January 11, 2001, SECOR oversaw destruction of domestic well DW-2, located south of
<br /> Ranch Market (Figure 2). Details of the well destruction are described in SECOR's DW-2 Well
<br /> Destruction Report, dated January 23, 2001.
<br /> On December 20, 2000, SECOR began oversight of the installation of domestic well DW-2R,
<br /> the replacement domestic well for DW-2. From December 28, 2000 to January 5, 2001, the
<br /> dedicated well pump, pressure tank,concrete pad, and well-related underground electrical and
<br /> water service line was installed. Details of the well installation are described in SECOR's
<br /> Domestic Well Installation Report(DW-2R), dated February 1, 2001.
<br /> On January 8, 2001, SECOR sampled DW-2R and submitted the water sample to Kiff
<br /> Analytical for BTEX,TPHg, oxygenates, 1,2-DCA, and EDB using EPA method 8260B. The
<br /> sample was also analyzed at CLS for Nitrate/Nitrite using EPA method 300.0. SECOR
<br /> collected confirmation water samples from DW-2R on January 11, 2001,and again on January
<br /> 15, 2001. Analytical data is summarized in Table 3.
<br /> After review of the confirmation samples,the San Joaquin County Environmental Health
<br /> Department(SJCEHD)requested the well be brought online. On January 18, 2001, SECOR
<br /> met with Mr. Michael Infuma with SJCEHD for the final inspection of well DW-2R. The
<br /> water service from the Aero Pure Water supply tank was disconnected and the water valve was
<br /> opened,allowing DW-2R to supply water to the home on the Pantoja Property.
<br /> Hvdrogeoloev
<br /> The depth to groundwater ranges from 26 to 32 feet bgs in the on-and-offsite wells.
<br /> Historically, groundwater flow direction has been southerly. Groundwater gradient was 0.005
<br /> foot per foot in the second quarter 2001. Surface drainage is to the southeast, towards the
<br /> Stanislaus River, located approximately 750 feet south of the Site.
<br /> Litholo2v
<br /> Based on the description of the soil samples collected from the soil borings, the lithology at the
<br /> File:Ranch Market\WorkPlan\Rb-CPT Workplan.doc
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