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(:VkTc 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 October 19, 2004 The groundwater monitoring data are summarized in Table I Monitoring data and purge logs are provided in Attachment 1 LABORATORY ANALYSES The groundwater samples collected on October 19, 2004 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, aluminum, potassium, and sodium using EPA Method 200 7, chloride and sulfate by EPA Method 300 0, phosphorus by EPA Method 365 3, trichloroethene (TCE) and tetrachloroethene (PCE) by EPA Method 8260B, and total hardness as CaCO3 by EPA Method 234013 Groundwater samples collected from wells MW-1 through MW-9, FW and were inadvertently not analyzed for dissolved calcium Additional analyses for PCE, TCE, and Aluminum were requested by the RWQCB in an e-mail correspondence dated July 12, 2004 Cr +6 was not present above laboratory detection limits in the sample collected from the facility well 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 5 8 mg/l The reported Cr +6 concentration in the groundwater sample collected from MW-6 was 0 063 mg/l 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 wells MW-3 and MW- 6 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 4 9 mg/l The reported total chromium concentration in the groundwater sample collected from MW-6 was 0 063 mg/l Total chromium was also detected in water samples from wells MW-I MW-2 MW-4, MW-5, MW-7, MW-8, MW-9, and the facility well, but at concentrations below the MCL for total chromium Tetrachloroethene, also known as Perchloroethene (PCE) was not present above laboratory detection limits in the groundwater sample collected from wells MW-2, MW-4, MW-5 MW-6, or the facility well PCE was detected in the groundwater samples collected from monitoring well MW-9 at a concentration above the MCL for PCE in drinking water of 0 005 milligrams per liter (mg/L) The reported PCE concentration in the groundwater sample collected from MW-9 was 0 0580 mg/L PCE was also detected in water samples from wells MW-1, MW-3, MW-7, and MW-8, but at concentrations below the respective MCL for PCE The distribution of PCE in groundwater is shown on Figure 5 s lenvironmentni1625831quarterlyl4gr-2004 doe 2