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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 0 Dissolved oxygen MONITORING RESULTS ' GROUNDWATER Groundwater monitoring data for the first 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 these constituents. Since the ANOVA is not a very powerful test, and there are no increasing trends the County believes these wells are still unimpacted. ' 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 first 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 March 15,200 1. While under review, the County will continue to sample and evaluate MW-3 for VOC's. A trace detection of Methylene Chloride was found in MW-2 during the first quarter monitoring event. ' Methylene Chloride was also detected in the field and trip blanks. Due the fact that Methylene Chloride has not been detected for the past three quarters and it is commonly used as a laboratory solvent, the County believes this detection to be laboratory error. This is also only one trace ' concentration 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. Surface Water First storm samples were taken during the first quarter monitoring event. A tabular summary of the results can be seen in Table 2. The parameters that could be statistically analyzed were tested with ' the interwell tolerance limit and all constituents are within concentration limits. Tolerance limits were not established for TDS, Sulfate, and Nitrate because the false positive rates for these constituents is greater than 5%. For these constituents an ANOVA test was performed and the results showed no variances between background and compliance data. Therefore it is concluded that there are no exceedances. ' 6