SITE INFORMATION AND CORRESPONDENCE

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Mr. Maurice Benson November 19, 2008 Page 3 SVE Source Areas: Two of three SVE areas at DDJC-Tracy are proposed for no-further action (NFA) by DESJC. Analytical soil gas and groundwater data indicate that residual contaminant mass remains in both unsaturated and saturated soil above the cleanup goals in Area 1 & Area 3, potentially acting as a continuing source of VOC contamination for groundwater. The regulatory agencies participated in conference call with DESJC on November 4, 2008 and stated that the soil vapor cleanup objectives specified in the DDJC-Tracy Record of Decision (ROD) have not been met at Area 1 and Area 3, and that further SVE work is warranted prior to the NFA approval. DESJC should eliminate these contaminant sources for groundwater prior to proposal of OU1 rebound test. Warehouse 10 Persistent GW Source: United States Environmental Protection Agency Region IX soil screening levels for TCE are exceeded at several locations in soil beneath the Warehouse 10 foundation, indicating a continuing threat to groundwater quality, confirmed by localized TCE groundwater concentrations as high as 32.8 micrograms per liter (Ng/L). Fieldwork efforts by the Army Corps of Engineers have recently removed the Warehouse 10 structure, in anticipation of building a parking lot, as stated by DESJC. Part of Warehouse 10 is designated as Solid Waste Management Unit (SWMU) 20, and 33, as the site was the former location of a TCE solvent tank, and Industrial Waste Pipeline, respectively. SWMU 20 and SMWU 33 were identified as locations of Institutional Controls (ICs) in the DDJC-Tracy ROD. Specifically, the ICs prevented additional remedial fieldwork in locations that would undermine the stability and support of the Warehouse 10 structure. Since the Warehouse 10 structure no longer exists, the ICs constraints are effectively removed, and allow for the remaining VOC soil contamination to be remediated, presumably by SVE, the most efficient and effective method for VOCs in unsaturated soil. DESJC should remove the remaining VOC mass from unsaturated soils beneath Warehouse 10 to eliminate the persistent source of VOC contamination to groundwater prior to an OU1 Rebound Test.