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ik'9 K.LEINFELDER .6 CONCLUSIONS AND RECOMMENDATIONS On December 9, 2002, six monitoring wells were purged and sampled. Water samples obtained from each location were submitted for chemical analysis. f Based on the data obtained during our assessment, the following conclusions and recommendations have been formulated; 1. Groundwater flow direction at the site is estimated to be towards the southeast at approximately 0.0005 ft./ft. This is consistent with the historical groundwater data collected at the site. 2. Based on the results of the groundwater sampling it appears that the groundwater quality has remained relatively consistent with the first three sampling events this year. The results showed no TPH-g benzene, toluene, ethylbenzene, xylene, EDB, TBA, DIPE, ETRE, or TAME detected in any of the monitoring wells sampled this quarter. 1,2-DCA was detected in three .of the six groundwater samples analyzed with the f detected concentrations ranging from 0.66 ug/l (MW-DIS-12) to 170 ug/l (MW-11s). This sampling event marks the second time 1,2-DCA was detected in MW-DIS-12. 1,2-DCA has been detected consistently in MWA Is since monitoring began in February 2002. The remaining three groundwater samples showed non-detect concentrations of 1,2-DCA above the laboratory reporting limit (ND <0.5 ug/1), The PMCL for 1,2-DCA is 5 ug/l. The detected concentration of 1,2-DCA in MW-DIS- 12 and MW-DIS-14s did not exceed the PMCL for 1,2-DCA in groundwater. However, the concentration detected in MW-I Is did exceed the PMCL for 1,2-DCA. MTBE was detected in the groundwater sample collected from MW-DIS-14s with a concentration of 2.5 ug/1. This marks the third consecutive quarter that MTBE has been detected in MW-DIS-14s. MTBE was not detected in the remaining five samples. The PMCL for MTBE is 13 ug/I and the SMCL for MTBE is 5 ug/1. The detected concentration of MTBE in MW-DIS-14s does not exceed the PMCL or the SMCL for MTBE in water. PMCLs are derived from health based criteria, whereas SMCLs are derived from human welfare considerations such as taste and odor. Kleinfelder recommends that monitoring of the site should be continued in accordance with the"Groundwater Monitoring Frequency Decision Tree at this time. A copy of this report should be submitted to the San Joaquin County Public Health Services Department Environmental Health Division and the Central Valley Office of the State.of California Regional Water Quality Control Board by Del Monte, Inc. for their review and consideration, This report is subject to the limitations found in Chapter 7 of this report. 12280.MON/ST03R225 Page 10 of 12 2003,Kleinfelder,Inc February 5,2003