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CSUS-Multi Campus Regional Center—Quarterly Groundwater Monitoring November 11,2002 Page 3 1 Table 2 Groundwater Analytical Results (September 11,2002) Sam le Number 3024-MW1 3024-MW2 3024-MW3 Analyte Units—. L L /L a Benzene <0.5 <0.5 5.0 Toluene <0.5 0.5 0.7 Ethyl benzene <0.5 <0.5 5.5 Total xylenes. <1.0 <1.0 4.9 TPH-G <50 100 680 TPH-D <50 <50 350* MTBE <0.5 <0.5., 160 Ethanol <20 <20 <200 Tertiary-butanol <5.0 <5.0 <50 Di-isopropyl ether <0.5 <0.5 <5.0 I Ethyl tertiary-butyl ether <0.5 <0.5 <5.0 Tert-am l methyl ether <0.5 <0.5 <5.0 1,2-dichloroethane <0.5 2.5 74 1,2-dibromoethane <0.5 <0.5 <5.0 ( Unit Conversions: Analytical pg/L;parts per billion(ppb) TPH-G=total petroleum hydrocarbons quantified as gasoline. TPH-t)=total petroieum hydrocarbons quantified as diesel MTBE—methyl tertiary-butyl ether '=sample chromatogram does not match standard diesel chromatogram and the result is an estimated value SUMMARY AND PROPOSED FUTURE WORK The current quarterly monitoring data indicate that groundwater conditions at the site have ren'ained - relatively static. The laboratory analytical results of the current monitoring are consistent with the historical laboratory analytical results. The current groundwater gradient direction (southeast) is consistent with the gradient measured during the previous monitoring event conducted on June 28 2002 but varies from the gradient direction measured during the soil and groundwater investigation activities !, conducted on December 18, 2001 (due east). Based on the results of the current and historical groundwater monitoring data, Condor recommends that quarterly groundwater monitoring of MW-1, MW-2, and MW-3 continue. The next groundwater sampling event is scheduled for December2002. In a letter dated April 26, 2002 to Mr. Cliff Bailey of California State University Stanislaus, Rebecca Setliff of the SJCEHD requested that a work plan be submitted to further investigate the vertical and lateral extent of impacted groundwater, and to compare at least two different, but feasible, remediation alternatives for mitigating contamination in the soil and groundwater at the site. Condor is currently preparing a Problem Assessment Work Plan (PAWP)to comply with Ms. Setliff's request. LIMITATIONS AND SIGNATURE Condor has endeavored to determine as much as practical about the site within our scope of services using 4' accepted principles and professional practice at the time the work was performed. Condor's involvement in the work performed for this report has been limited to collecting and recording system measurements and parameters; collecting and shipping samples; compiling field data and data provided by analytical laboratories; and interpreting field and laboratory ,data. Condor makes no representation as to the subsurface conditions at locations or times other than those sampled by our employees and reported in { this document. Condor is not responsible for the accuracy and completeness of information collected and developed by others. t.a CONDOR