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Ms Mary Meays Page 4 August 12, 1996 hydrocarbon concentrations over the past several years and the lack of apparent plume migration indicate that intrinsic bioremediation is occurring at the site, and that the necessary requirements for the success of this technology have been met Catellus proposes to implement ORC using the following existing onsite wells • Wells MW-1, MW-4, MW-5, and the vapor extraction well installed in the excavation pit, if it contains water (for Former Tank Site #1), and • Wells MW-1A, MW-2A, MW-3A, and MW-4A (for Former Tank Site #2) Under this process, a patented formulation of very fine, insoluble Magnesium Peroxide (M902) that releases oxygen at a slow controlled rate (typically 8 to 10 mg/1) when hydrated, is mixed in a carrier matrix and contained in inert filter socks placed into the wells Contact with ground water will initiate the release of oxygen, and the flowing action of the ground water will disperse oxygen in the surrounding saturated zone for use by micro-organisms to degrade hydrocarbon When oxygen readings in the well return to background levels, the socks are removed from the well and replaced with new socks At Former Tank Sites #1 and #2, ground water flow is influenced by a natural gradient and tidal fluctuations These influences are not expected to decrease the effectiveness of this remediation strategy CONCLUSIONS As in past sampling events, TPH as gasoline and diesel, and BTEX compounds were detected in ground water at the Catellus properties located at 1325 and 1515 West Weber Avenue At Former Tank Site 1, TPH and BTEX compounds were detected in MW-5, and TPH-diesel was detected in MW-3 At Former Tank Site 2, TPH and BTEX were detected in MW-1A and MW-2A TPH and BTEX concentrations in ground water are generally low, the distribution of these compounds is restricted to the immediate vicinity of the former tanks, and historical results indicate that the plumes do not appear to be migrating If, after review of these data, remediation is deemed appropriate by PHS/EHD as previously indicated, enhanced bioremediation appears to be the most viable option Intrinsic bioremediation appears to already be occurring at the sites, and can be enhanced using Oxygen Release Compound bioremediation techniques to increase the rate of degradation This technology is proven, and is compatible with site conditions and the nature and extent of chemicals in ground water As previously discussed, Catellus wishes to obtain closure of the properties, and is willing to undertake a certain level of remediation, as appropriate, to this end The ORC technology could be easily implemented during the next monitoring event at the sites, which is due in the near future We look forward to discussing