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CVATC A S S O C I A T E S I N C 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 19, 2005 The groundwater monitoring data are summarized in Table 1 Monitoring data and purge logs are provided in Attachment 1 LABORATORY ANALYSES The groundwater samples collected on January 19, 2005 were submitted to Excelchem Environmental Labs, Environmental Laboratory Accreditation Program (ELAP) #2119, in Roseville, California for analyses of hexavalent chromium (Cr +6) using EPA Method 7199, total chromium, using EPA Method 200 8, chloride by EPA Method 300 0, VOCs by EPA Method 826013, total hardness as CaCO3 by EPA Method 2340B, and aluminum by EPA Method 6010B Cr+6 was detected in the groundwater samples collected from monitoring wells MW-3 and MW- 6 at concentrations above the California Primary Maximum Contaminant Level (MCL) for total chromium in drinking water of 0 05 milligrams per liter (mg/1) The reported Cr+6 concentration in the groundwater sample collected from MW-3 was 2 4 mg/1 The reported Cr+6 concentration in the groundwater sample collected from MW-6 was 0 068 mg/1 Cr *6 was also detected in water samples collected from wells MW-1, MW-2, MW-4, MW-5, MW-7, MW-8, and MW-9, but at concentrations below the MCL for total chromium The distribution of Cr +6 in groundwater is shown on Figure 4 Total chromium was detected in the groundwater samples collected from well MW-3 above the California Primary MCL for total chromium in drinking water of 0 05 mg/l The reported total chromium concentration in the groundwater sample collected from MW-3 was 2 6 mg/1 Total chromium was not detected in water samples from wells MW-1, MW-2, MW-4, MW-5, MW-6 MW-7, MW-8, MW-9, at or above laboratory detection limits for total chromium Tetrachloroethene, also known as perchloroethene (PCE) was not present above laboratory detection limits in the groundwater samples collected from wells MW-2, MW-4, MW-5, or MW- 6 PCE was detected in the groundwater samples collected from monitoring wells MW-7 and MW-9 at concentrations above the MCL for PCE in drinking water of 0 005 milligrams per liter (mg/L) The reported PCE concentrations in the groundwater samples collected from MW-7 and MW-9 were 0 0076 and 0 049 mg/L, respectively PCE was also detected in water samples from wells MW-1, MW-3, and MW-8, but at concentrations below the respective MCL for PCE The distribution of PCE in groundwater is shown on Figure 5 TCE was not present at or above laboratory detection limits in the groundwater samples collected from MW-1 through MW-9 Chloride in the groundwater samples collected from wells MW-1 through MW-9 ranged from 20 mg/L (MW-4) to 420 mg/L (MW-3) Hardness as a measure of calcium carbonate in the groundwater samples collected from wells MW-1 through MW-9 ranged from 290 mg/L (MW- slenvironmental1625831quarterlyllgr-2005 doe 2