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3. Construct temporary vapor sampling points at the 4.5-5 foot depth interval by setting a new steel vapor tip and screen within approximately six inches of store-bought sand-pack at the bottom of each hole. The remaining annulus surrounding the TeflonTM tubing connected to the vapor tip/screen will be sealed with hydrated bentonite to ensure a tight seal and preclude direct short-circuiting to the atmosphere. Such short-circuiting is often a problem with alternate vapor sampling point techniques that involve driving and retracting a rod. Each tubing riser will be topped with a closed valve in preparation for sampling the following day, and all locations will be protected from interim disturbance. More specifics concerning this installation work are presented in the appended Standard Procedures. 4. Collect vapor samples from the five points in laboratory-supplied, evacuated Summa canisters following the protocols presented in the appended Standard Procedures. The protocols cover the steps used to verify that no leaks are present and to purge the system before sample collection. One QA/QC duplicate sample is planned from the group. At the completion of sampling activities, the tubing will be pulled from each expendable tip/screen and the five holes fully sealed to grade. 5. Submit the six vapor samples (five plus a duplicate) along with chain-of-custody documentation to Air Toxics Ltd, a state-certified laboratory in Folsom, that will be fin instructed to analyze them for total petroleum hydrocarbons as gasoline (TPHg), plus the, four main aromatic compounds in gasoline — benzene, toluene, ethylbenzene and xylenes (BTEX). The testing will be conducted using modified EPA Method TO-15 GC/MS. 6. Submit the two representative soil samples to McCampbell Analytical and Cooper Testing Laboratory who will be instructed to analyze them for bulk density, porosity, moisture content, grain size distribution and total organic carbon (TOC). The testing will be conducted using established methods (e.g., ASTM, etc.). 7. Evaluate the analytical results with respect to general, conservative risk-based screening levels such as those set forth by the SFBRWQCB (2005). Our comparison will be with screening levels for residential exposure since that is the Site's predominant land use. Based on this evaluation we will either (a) contract with a toxicologist and Certified Industrial Hygienist to prepare a human health risk assessment, which will incorporate site-specific factors such as the physical soil properties and the mobile home particulars; or (b) proceed directly to Task 8. 8. Prepare a written report documenting the work performed, the findings gained and our comments and opinions. The report will include tables summarizing the data, figure(s) showing the points of vapor sampling, plus appendices of geologic logs, field data sheets, chain-of-custody records and certified lab reports. Page 3 of 4