SITE INFORMATION AND CORRESPONDENCE

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` • . Ms. Serra January 24, 2005 EarhTeeh Page 2 A Ty.Intematlonal Ltd Glmpany Scope of Work Activities described in this Work Plan include the following: • Install a soil gas probe(SV-26) in the vicinity of former soil gas location SV-25 to a depth of five feet below ground surface (bgs); • Install 3 additional soil gas probes(SV-27, SV-28, SV-29)approximately 10 feet out radially in a triangular pattern from SV-25 to a depth of five feet bgs; • Collect and analyze soil vapor samples for HzS by ASTM Method D-5504, and for methane by ASTM Method D-1946, and provide QA/QC data to verify the quality of the data; and • Summarize the results in a letter report submitted to RWQCB. Implementation of Field Work Pre-Field Activities • Perform work according to the existing Earth Tech Health and Safety Plan; • Prior to commencing fieldwork, Earth Tech will notify Underground Services Alert (USA)of the proposed drilling activities; • A private utility locator will also be employed to survey the sampling locations for the presence of subsurface utilities; • The appropriate drilling permit will be obtained prior to commencing field activities; and • A Public Notice document will be prepared and sent to the appropriate individuals on the distribution list as defined by RWQCB. The notice will consist of a single page,with English on one side and a Spanish translation on the other, and will include a form for interested parties to fill out to receive additional information. Installation of Soil Vapor Probes Earth Tech will collect four soil vapor samples in the vicinity of SV-25 (shown as proposed locations SV-26 through SV-29 on Figure 2). Similar to the previous sampling event of SV-25, the soil vapor probes will be installed vertically and samples obtained from a depth of 5 feet bgs. Upon completion of soil vapor sampling the borings will be grouted to the surface using a cement-bentonite mixture in accordance with permit requirements. Soil vapor samples will be collected in accordance with the guidelines provided by DTSC and the Los Angeles RWQCB Advisory-Active Soil Vapor Investigations dated January 28, 2003. Soil vapor samples will be collected using the Post Run Tubing(PRT) Active Sampling method. This method consists of advancing a 1.25-inch GeoProbe to the required depth and then withdrawing the tip of the probe several inches to expose the surrounding soils. A 3/8-inch PRT, located inside the GeoProbe, forms a vacuum-tight seal near the probe tip. The PRT will then be purged of ambient air using a dedicated Summa canister and flow regulator to purge at rates between 100 and 200 milliliters per minute (mL/min). A sampling canister (6-liter [6-L] Summa) will be