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' 0 Total organic carbon 0 Cyanide • Carbonate 0 Sulfide • Bicarbonate 0 Oil and Grease ' Total alkalinity 0 Chemical oxygen demand • Metals Dissolved oxygen MONITORING RESULTS ' GROUNDWATER Groundwater monitoring data for the second quarter of 2001 is presented in Table 1. Appendix E contains a tabular summary of the historical monitoring data. Concentration limits were updated this quarter, and monitoring results were compared to the limits presented on Table 1. In several instances the concentration limits could not be updated because the false positive rate is greater than 5%. An analysis of variance (ANOVA) test was performed and the results showed a variance in Chloride,Nitrate,Sulfate and EC in both down gradient wells. There were no significant increasing ' trends in Chloride,Nitrate, and EC. Increasing trends of Sulfate were found in MW-2 and MW-3. Although there were significant increasing trends, recent concentrations of Sulfate in the downgradient wells are less than those found in upgradient well MW-1. Further analysis and the fact ' that the ANOVA is not a very powerful test leads the County to believe that these are not exceedances,and the wells are unimpacted. The levels of Electrical Conductivity during the Second Quarter Monitoring Event were relatively high in all three wells. The County will continue to monitor the levels of EC to analyze the situation further. QUARTERLY MONITORING AND FIELD PARAMETERS A comparison of the quarterly, annual monitoring and field parameter results to the concentration limits in Table 1 shows that there are no exceedances this quarter where concentration limits could ' be determined. For the constituents that concentration limits could not be determined,further testing seems to show that these also are not exceedances. VOLATILE ORGANIC COMPOUNDS (VOC'S) During the second quarter monitoring event there were detections of 1,1-Dichloroethene and ' Trichloroethene in MW-3. The County has proposed an evaluation monitoring program to the Regional Board. The County submitted a revised Evaluation Monitoring Plan dated May 25,2001. While under review, the County will continue to sample and evaluate MW-3 for VOC's. Trace ' detections of Methyl tert-butyl ether and Toluene were found in MW-1 during the second quarter monitoring event. Methyl tert-butyl ether was also detected in the trip blank. The County believes this detection to be laboratory error. Since the detection of Toluene was in a trace amount, and it is ' the County's interpretation of the Standard Provisions and Reporting Requirements dated 1993,p. 12 that a discrete re-test is required when two or more VOC's are detected above the Method Detection Limit and below the Practical Quantitative Limit in one well during the same monitoring ' event, a re-test was not requested. Both constituents will continue to be monitored in the Third Quarter Monitoring Event. tSURFACE WATER First storm samples were taken during the first quarter monitoring event. During the second quarter monitoring event,no water was present for sampling. 6