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Mr. Brian Cobb August 29, 1995 ' Page 3 I isomers (BTEX) following California Air Resources Board (CARB) Method 401A modified ' A chain-of-custody form was used to record the possession of the sample from the time of collection to its arrival at the laboratory Results ' Figure 2 illustrates the vacuum measurements recorded at the observation well heads during the SVE pilot test conducted on Well MW-5 as a function of distance from the SVE test well This figure indicates that a maximum radius of influence of approximately 50 feet, northwest ' of the test well, was achieved at a flow rate of 50 cfm at approximately 52 inches of water vacuum during the pilot test conducted on Well MW-5. However, influence was not identi- fied in Well MW-2, directly north of the test well, at a distance of approximately 46 feet A graph of the concentration of VOCs in the effluent airstream, recorded using the field PID, throughout the duration of the SVE pilot test conducted on Well MW-5 is included as ' Figure 3. Analytical results of the effluent air sample collected from Well MW-5 at the end of the pilot test identified TPHg in the sample at a concentration of 63 parts per million by volume (ppmv) BTEX constituents were identified in the sample at concentrations ranging from less than 0 013 ppmv to 1.6 ppmv Analytical laboratory data sheets are attached These results indicate that SVE is capable of removing TPHg and BTEX from the soil beneath the site. 1' Conclusions and Recommendations TheP ulsing-of the Rotron blower and the use of groundwater wells instead of SVE wells during the pilot test most likely resulted in an deceptively small radial influence Based on ' the lithology beneath the site, a larger SVE influence is expected to occur during a continuously operating a remediation system Based on the sporadic results obtained during the pilot test conducted on Well MW-5, the subsurface lrthology in the vicinity of the site, and our experience with SVE remediation systems, Brown and Caldwell believes that SVE may be an applicable alternative for remediating the Site 1 We recommend that several wells specifically designed for SVE be installed and an extended pilot test be conducted prior to designing and constructing a permanent remediation system ' for the Site. In addition, we recommend that several dual completion, air sparging/soil vapor extraction (AS/SVE) wells be installed and that an extended AS test also be conducted I I I oe117195\E UlMlMR154S071LPR-01 wPs I I M.eerl[IP ! I I I ' Brown and Caldwell �' II Consu16ntS I i R