SITE INFORMATION AND CORRESPONDENCE

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JUN/14/2006/WED 01:52 PM COS PSG & REDEV FAX N. 20993750gq P.006 Ms. Kitty Walker 5 7 June 2006 The Investigation Work Plan contains a task titled "French Drain Alignment Survey," which proposes to conduct "a field survey to evaluate if the drain [pipe] is present, and if present, the length and direction of the drain. The survey will include spot excavations along 60 to 100 foot alignMents for the former rail line to search for the French drain, and if found, the orientation surveyed." The Investigation Work Plan is not sufficiently detailed to accomplish the necessary work. The RDA needs to incorporate the following work items into this task: The excavated soil requires a management plan. A liquid management plan is also necessary. The proposed excavation spacing of "50 to 100 feer is vague and is insufficient. The excavation spacing should be every 26 feet along the length of the railroad corridor within Project Areas 3, 4 and 24, and should uncover a good portion of the pipeline. o Once the pipeline is uncovered, it cannot be breached without a plan and the equipment available to extract any fluids present in the pipeline. . The Investigation Work Plan must contain provision to investigate the railroad corridor off-site of Project Areas 3, 4 and 24, to the full extent that the drainpipe and pollution extend. Excavated where polluted soil is found cannot be backfilled until polluted soil is excavated to the extent necessary as determined by Cehtral Valley Water Board staff. Excavations areas require sidewall and groundwater sampling. Site security measures are necessary. The Investigation Work Plan proposes to conduct a video survey of the interior of the drainpipe, but not much detail is provided. The RDA should detail' this work and describe the procedure under which the data obtained will be used.. Soil Gas Survey The Investigation Work Plan contains provisions to conduct a soil gas survey (SGS) concentrating its efforts on Project Area 4 and 24. Attachment 7 shows the proposed locations of the soil gas sampling modules, with 7 modules planned for Project Area 4 and 28 Modules planned for Project Area 24, stating, "Soil gas sampling will not be performed in Parcel [Project Area] 3 due to recent remedial actions performed and subsequent site development" However, the excavation and remediation conducted on Project Area 3 was limited to the area beneath the building pad for the WorkNet building. North of the excavation (see Attachment 3) at soil boring SB-5 the soil was reported to contain about 1,800 mg/kg of total petroleum hydrocarbons, the soil boring SB-7, south of the excavation, contained about 5.7 mg/kg of total petroleum hydrocarbons. The Investigation Work Plan is not sufficiently detailed to accomplish the necessary work. The RDA needs to investigation the portion of railroad corridor that was not excavated and is part of Project Area 3. The RDA reported that the release is older than 20 years. Degradation is known to reduce vapor levels for hydrocarbon fuel mixtures. Thus, SGS data indicating that pollution is not present will not be a sole deciding factor.