SITE INFORMATION AND CORRESPONDENCE_1994-1996

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Mr. Darren Denning -2- 3 October 1994 As stated above, the purpose of the pilot study was to determine if SVE is a viable technology to remediate fuel-contaminated soil and ground water at the site. Using data obtained from other sites, albeit similar, does not make sense when onsite data can be obtained easily. The absence of vacuum in the OWs during the test does not mean that SVE is not viable. As stated in the report, the low permeability of the vadose soils and the limited well screen above the saturated zone could have caused the absence of vacuum in the OWs. In MW 16, the absence of vacuum in the OWs was likely caused by their distance from MW 16. Another possible cause is short-circuiting from the surface. This would explain the lack of influence by MWs 2 and 20 in spite of the relative proximity of their respective OWs. Pacific should redo the test after addressing the possible causes of the zero vacuum in the OWs. The low permeability of the vadose zone soils can be compensated by increasing the vacuum in the EWs. The small screen length above the saturated zone can be increased by drawing down the water table or installing OWs with longer screen lengths. Short-circuiting can be overcome by putting a liner over the expected area of influence of the EWs. If, after performing these minimum corrective measures, the test still shows no vacuum in OWs, then SVE is not a viable option. However, to say that SVE would work based on test data from other sites is premature and defeats the purpose of the pilot study. By 28 October 1994, please address the above comments and submit a time schedule to redo the SVE pilot test. You may call me at (916) 255-3049 if you have any questions. LUL�A1/ ,v>r PHILIP S. ISORENA Associate Engineer PSI:psi/lsb cc: ✓Mr. Harlin Knoll, San Joaquin Public Health Services, Stockton Mr. Brad Boschetto, Anaheim Mr. Justin L. Hawkins, Pacific Environmental Group, Inc., San Jose