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Cyj&TC A S S O C I A T E S I N C . east with an average magnitude of 0.001 ft/ft. This appears to be within historical parameters, which have indicated the predominant groundwater gradient direction is to the east with variation between northeast and south-southeast. Figure 3 depicts groundwater elevation contours for January 28, 2003. The groundwater monitoring data are summarized in Table 1. Monitoring data and purge logs are provided in Attachment 1. LABORATORY ANALYSIS The groundwater samples collected on January 28, 2003 were submitted to Excelchem Environmental Labs (ELAP 42119) in Roseville, California for analysis of. hexavalent chromium using EPA method 7199; total chromium, calcium, sodium, and potassium using EPA method 200.7; ammonium by method SM 4500-NH3 b; chloride using EPA method 300.1; sulfate using EPA method 375.4; phosphorous using EPA method 365.3, and hardness as CaCO3 by method SM2340C. Hexavalent chromium was not present above laboratory detection Iimits in the sample collected from the facility well. Hexavalent chromium was detected in monitoring well MW-3 and MW-6 above the California Primary Maximum Contaminant Level (MCL) for total chromium in drinking water of 0.05 milligrams per liter (mg/1). The reported hexavalent chromium concentration in well MW-3 was 3.4 mg/l. The reported hexavalent chromium concentration in well MW-6 was 0.092 mg/l. Hexavalent chromium was also detected in water samples from wells MW-2, MW-4, MW-5, MW-7, and MWS but at concentrations below its respective MCL. The distribution of hexavalent chromium in groundwater is shown on Figure 4. Total chromium was detected in monitoring well MW-3 and MW-6 above the California Primary MCL for total chromium in drinking water of 0.05 m9/1 . The reported total chromium concentration in well MW-3 was 3.6 mg/l. The reported total chromium concentration in well j MW-6 was 0.097 mg/l. Total chromium was also detected in water samples from wells MW-1, MW-2, MW-4, MW-5, MW-7, and MW8 but at concentrations below the respective MCL for total chromium. Total chromium was not present above laboratory detection limits in the water ; sample collected from the facility well. i Sulfate, calcium, sodium, and potassium Were detected in wells MW1 through MW8 and the facility well. Phosphorous was also detected in wells MW-1, MW-2, MW-4, MW-5, MW-7, and MW8. Chloride was detected in wells MW1 through MW8 and the facility well with the highest concentration in well MW3. Hardness as a measure of calcium carbonate was detected in wells in wells MW1 through MW8 and the former facility well with the highest concentration in well MW3. Analytical results are summarized in Tables 2 and 3. Laboratory data sheets and chain- of-custody documentation are provided in Attachment 2. DISCUSSION AND CONCLUSIONS Based on a review of previous work performed at this site and the data presented in this report, it can be concluded that groundwater gradient direction have been generally consistent with historical data. z wA625831quartly%Igr-2003.doc 2