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CSUS-Multi Campus Regional Center—Quarterly Groundwater Monitoring November I i,2002 Pane 2 Summary of September 2002 Quarterly Groundwater Monitoring Results (continued) Groundwater Contamination continued Maximum Concentration: Benzene Benzene(µg/L) 5.0 MTBE MTBE(pg/L) 160 1,2-DCA 1,2-DCA(lsg/L) 74 Nature of contamination: TPH-G TPH-G (gg/L) 680 TPH-D TPH-D(gg/L) 350 Toluene Toluene(pg/L) 0.7 Ethyl benzene Ethyl benzene(4g/L) 5.5 Xylenes Xylenes(µ L) 4.9 FIELD OBSERVATIONS No separate phase petroleum or sheen was noted in the groundwater recovered from the wells. A slight petroleum odor was noted in the groundwater recovered from MW-3. Groundwater monitoring field forms are attached. GROUNDWATER ELEVATIONS AND GRADIENT On September 11, 2002 the depth to groundwater was measured in monitor wells MW-1, MW-2, and MW-3. Groundwater elevation data is presented in Table 1, below. The average depth to groundwater in the monitor wells was approximately 39.09 feet below the surveyed well collar measuring points (the measuring points are slightly below the ground surface). The average groundwater elevation measured in the monitoring wells decreased approximately 1.9 feet between June 28, 2002 and September 11, 2002. The estimated groundwater gradient for the site on September 11, 2002 was 0.0017 ft/ft to the southeast and is shown in attached Figure 2. Table 1 Groundwater Elevation Data (September 11,2002) Well Number Well Collar Elevation feet) Depth to Groundwater(feet) Groundwater Elevation feet MW-1 17.42 39.04 -21.62 MW-2 17.59 39.30 -21.71 MW-3 17.16 38.92 -21.76 All measurements are in feet. TOC=Top of Casing TOC Elevation:Referenced to NAVD88 datum from NGS.Benchmark HS3999. LABORATORY ANALYTICAL RESULTS All groundwater samples were analyzed for total petroleum hydrocarbons quantified as diesel (TPH-D) and gasoline (TPH-G), and for benzene, toluene, ethyl benzene, and total xylenes (BTEX) by EPA Method 80151n/8020; and for gasoline oxygenates/additives by EPA Method 8260B. The gasoline oxygenates/additives include methyl tertiary-butyl ether (MTBE), ethanol, tertiary-butanol (T-BUT), di- isopropyl ether (D1PE), ethyl tertiary-butyl ether (ETBE), tertiary-amyl methyl ether (TAME), 1,2- dibromoethane, and 1,2-dichloroethane (1,2-DCA). Excelchem Environmental Labs of Roseville, California analyzed the groundwater samples. The laboratory analytical results for the groundwater samples collected from the monitor wells on September 11, 2002 are presented in Table 2, on the next page, and in Figure 3, attached. Historical groundwater monitoring data are included in Table A, attached. The laboratory certificates of analyses and chain-of-custody record are also attached. } 4M �„a CONDOR