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Mr Daniel K Barber, P E September 9, 2003 Page 14 of 17 appears to be a seasonal perched groundwater was found in the 1999 bores, and the 1 relatively high residual concentrations of greater than 10,000 mg/kg TPHd found in the 30-to 40-foot bgs zone in soil may reflect TPH sorption from groundwater ■ The apparent contaminants of concern are diesel contamination, with minor to no BTEX detected in the five consecutive quarterly groundwater sampling events initiated in June 2002 ■ Hydraulic and hydrochemical trend analyses show a north by northeastern flow direction and a relatively stable hydrochemical trend line, with some correlation between higher groundwater elevations and higher concentrations of TPHd ' ■ According to a water well survey, the nearest wells are the onsite non-potable water supply well located approximately 200 feet upgradient of MW-1 and the offsite non- potable agricultural well located approximately 300 feet downgradient of the northeast property line The offsite well draws water from a depth of 340 feet bgs, which is 290 feet deeper than the shallow 50-foot-deep groundwater contamination The relatively low (less than 0 5 mg/L TPHd) hydrocarbon contamination near the property's downgradient boundary, coupled with the lateral and vertical distance to the nearest receptor well, suggests a low probability of impact to that well ■ There are no drinking water MCLs for TPHg or TPHd There are MCLS for BTEX, however, no BTEX was detected in the five consecutive monitoring events While the State of California considers all groundwaters to be potential drinking water sources, as does SJCEHD, until a site-specific variance has been obtained, it is our understanding that groundwater is not used as drinking water in this area due to high total dissolved solids/turbidity associated with the upgradient Victor Sausage site (Gallardo & Associates, 1999) ' OPINION AND RECOMMENDATIONS The available data and discussions with SJCEHD indicate that further definition of the plume is required to identify its extent before SJCEHD will consider case closure Specific ' recommendations are ■ Prepare a workplan describing the additional investigation needed to address outstanding tissues for submission to SJCEHD ■ Complete an additional five to six exploratory bores by Cone Penetration Testing (CPT) ' In addition to collecting lithologic and "grab" groundwater samples to confirm the extent of the plume, the CPT provides a means of determining soil relative density, strength and Stellar Environmental Solutions ZBROlEC15 3wACU•e FT°%`+1W5.auPhB->�lndClueaR•v�ud FueillF,PORT-SM-�930N doe