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C A M B R I A Cambria also proposes to install one monitoring well screened in the second water-bearing zone adjacent to existing well MW-5. For the purpose of distinguishing between the two wells, we are renaming MW-5 as MW-5A. MW-5A is the existing well screened in the first water-bearing zone. The proposed well (MW-5B) will be screened in the second water- bearing zone. Installing this deeper well will allow us to assess the vertical gradient beneath the site and to determine if the deeper zone has been impacted by MTBE. Cambria may install a second deeper well, contingent upon the results from the earlier phases of this investigation, outlined above. If groundwater from the shallow wells MW-7 and/or MW-8 is found to be impacted, Cambria will install one deeper well adjacent to well MW-7 or MW-8. If the shallow groundwater from these wells is not impacted by MTBE, Cambria will review the results from well MW-513, and submit axecommendation regarding the installation of a second deep well in our February 16, 2001 report. Cambria is currently scheduled to install the deeper well(s) the week of January 22, 2001. A Cambria geologist will supervise the drilling and describe encountered soils in the well boring(s) using the Unified Soil Classification System and Munsell Soil Color Charts. Soil samples will be collected at five-foot intervals for lithoiogic description, possible chemical analysis, and organic vapor screening with a photo-ionization detector (PID). PID readings will be recorded on the boring log for each boring. Soil samples will be retained in stainless steel or brass sample tubes and will be covered on both ends with Teflon sheets and plastic end caps. Soil samples will be labeled, entered onto a chain-of-custody record and placed into a cooler with ice for transport to a State of California certified laboratory for analyses. The well boring depth(s) will be determined using the CPT logs. The well(s) will be completed using four-inch diameter Schedule 40 PVC casing. Well screen length will be no more than ten feet, and the interval will be determined using the CPT logs. The sandpack will be placed from the bottom of the well screen up to two feet above the top of the well screen followed by a two-foot thick bentonite seal and cement grout to grade. Each well will be secured with a locking cap under a traffic-rated well box. A licensed surveyor will survey all wellhead elevations relative to mean sea level and tie them into the Chevron well survey. The scope of work described in this work plan will be performed under the supervision of a registered geologist. ]346 4 i F