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Protect Number 18048K04 March 22 2007 DW-2BB: This deeper well is located along North Stockton Street. This well monitors deeper water along the eastern perimeter of the PCE plume. This well has been sampled quarterly from January 2004 through September 2006. PCE has been reported as non-detect during this time period. As it is likely that PCE will continue to be reported as non-detect in this well and because it monitors deeper groundwater along the perimeter plume core area, it is proposed that this well be sampled on an annual basis instead of a quarterly basis. DW-3BB: This deeper well is located along East Oak Street, just east of well MW-5BB. This well monitors deeper water just outside of the PCE plume core. This well has been sampled quarterly from January 2004 through September 2006. PCE has been reported as non-detect during this time period. As it is likely that PCE will continue to be reported as non-detect in this well and because well DW-4BB (a proposed new well) would monitor deeper water beneath the PCE plume core area, we recommend that this well be sampled on an annual basis instead of a quarterly basis. EX-1 BB: This well is located within the PCE plume core along East Oak Street. This well has been sampled quarterly from January 2004 through September 2006. PCE has been detected at concentrations ranging from 10 µg/l_to 430 pg/L during this time period. As this well monitors the PCE plume core, it should continue to be monitored on a quarterly basis. The proposed well sampling program described above is summarized in Table 1. Pr000sed Additional Deep Monitoring Well At the meeting the City of Lodi representatives expressed a desire to install an additional deep (DW-4BB proposed) groundwater monitoring well to a depth of approximately 95 feet and screened for five feet at the bottom. The proposed location for this well is close as practicable to groundwater monitoring well MW-6BB on E. Walnut Street. The rationale for a deep monitoring well at this location is that it will monitor deep water quality near the down gradient extent of the shallow,groundwater plume along the axis of shallow contaminant migration. After installation, the well should be sampled on a quarterly basis for the first year. Thereafter, sampling should be reduced to semiannually unless quarterly sampling data indicates otherwise. The Busy Bee representatives concur that a well in this location will complete the deep groundwater assessment. Performance Monitorinq Seven (7) performance monitoring wells (key wells) have been selected for the Site as follows: MW-06, MW-1 BB, MW-7BB, MW-9BB, MW-10BB, MW-19BB, and EX-1 BB. To achieve performance monitoring objectives related to cleanup goals, the seven (7) performance monitoring wells will be sampled concurrently during regularly scheduled sampling events, whenever possible. However, if performance monitoring data is needed at times independent of regularly scheduled sampling events, then the seven (7) wells will be sampled concurrently as necessary. EzC Remediation 5