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Mr Dann Rouse Exxon Company,U S A May 6, 1999 Page 2 concentrations of benzene, TPPH as gasoline, and MTBE is included as Figure 4 Cumulative ground water analytical results are summarized in Table 2 A copy of the laboratory analytical report with chain-of-custody documentation for the January 26, 1999 sampling event is presented in Enclosure B Remediation System Status A soil vapor extraction(SVE) system was installed at the site by Fugro West, Inc (Fugro) and operated for approximately 5 months from November 1995 to March I996 Performance data collected by Fugro are presented in Table 3 A new SVE system was installed by EA and was started on February 21, 1997 Soil vapor was extracted from two wells(VEW 1 and VEW2)because the screened intervals for the other wells used in the past for vapor extraction (MW2, MW3, and MW5) were submerged Influent TPPH as gasoline concentrations (prior to air dilution) and the estimated total pounds of hydrocarbons removed by the system are shown in Table 3 As can be seen in Table 3, as of March 30, 1998, the SVE system had removed approximately 1,551 pounds of TPPH as gasoline since the system was originally installed in November 1995. Laboratory analytical results for samples of the extracted soil vapor collected by EA are shown in Table 4 The SVE system was shut down from February 5 to March 26, 1998 for replacement of the activated carbon and to determine whether a rebound in extracted petroleum hydrocarbon concentrations would occur upon system restart The SVE system was sampled on March 30, 1998, three days after restart As can be seen in Table 4, the sample of extracted soil vapor had non-detectable concentrations of TPPH as gasoline and BTEX This result suggests that the SVE system has effectively removed the volatile petroleum hydrocarbons from the vadose zone The system operation was ceased on April 10, 1998 Future Work The next quarterly ground water monitoring and sampling is scheduled for May 1999 Remarks/Si atures The interpretations contained in this report represent our professional opinions, and are based in part on information supplied by the client. These opinions are based on currently available information and are arrived at m accordance with currently accepted hydrogeologic and engineering practices at this time and location Other than this,no warranty is implied or intended