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The vertical distribution of VOCs in groundwater within the LNC site vicinity is not as well <br /> defined because of the length of time between the discrete-depth HydroPunch samples collected <br /> in 1993 and 1994,soil gas samples collected in 1996, the multi-depth discrete groundwater <br /> samples collected during the City-wide sample event in 2000, and ongoing City of Lodi <br /> groundwater monitoring well sampling since 2000. When these data are plotted in cross-section <br /> (Figure 6), VOCs may be interpreted to be present in groundwater to a depth of at least 90 feet <br /> bgs in HPT05 under the LNC site,down to a depth of at least 115 feet bgs at HPT06,and 121 <br /> feet bgs at HPTO1 further downgradient(Figure 6). Shallow groundwater also is impacted south <br /> of HPT01 at soil boring C-37. <br /> Vertical profiling in City well CW 94 indicates the presence of VOCs in groundwater produced <br /> from water bearing zones located from 80 to 200 feet bgs(Figure 5)(Henshaw,2001). It is very <br /> likely that the presence of VOCs at significant depth beneath the LNC site and areas south of it is <br /> the result of continued pumping of City Water Supply Well CW#4. Downgradient of CW#4, <br /> the discrete-depth HydroPunch results from HPB02 and HPB03 indicate only the presence of <br /> PCE in shallow groundwater. VOCs were reportedly not present at a depth of about 90 feet from <br /> these sample points. This is consistent with the hypothesis that a source of PCE exists in this <br /> vicinity of the HPB borings(Busy Bee Site)and that VOCs entrained in groundwater producing <br /> zones upgradient of City well CW#4 may have been captured by pumping from City well CW <br /> #4. <br /> 4.6 Monitoring Well Sampling <br /> During the City-wide investigation conducted by the City of Lodi in 2000,twenty groundwater <br /> monitoring wells were installed and sampled. Of these, five monitoring wells were installed <br /> within the northern portion of the City of Lodi,including one well(MW-01)located immediately <br /> upgradient of the LNC site and one well(MW-02)located approximately 1,000 feet <br /> downgradient of the LNC site (Figure 5). No monitoring wells have been installed to date on the <br /> LNC facility. <br /> M nin\D AEnviroumeMelLL.NC\\10152007.wpd 21 <br />