SITE INFORMATION AND CORRESPONDENCE

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Mr. Shelby Lathrop - 2 - 8 August 2008 Former Tosco Bulk Terminal No. 013 f Table 3 in the Report shows that there were overall increases in DO concentrations in piezometers P-4, P-5, and P-6, which are screened between 35 and 45 feet bgs. ConocoPhillips attributes these increases to the oxygen injections into deeper injection points IP-10 through IP-12. However, only P-5 consistently met or exceeded the target DO level of 10 mg/L throughout May and June. In addition, MW-14 and MW-17B are also screened in the B zone, but DO levels did not increase appreciably in MW-14 and did not increase at all in MW-17B. DO levels in A-zone wells P-1 , P-2, P-3, MW-2, MW-8, MW-16, and MW-20 remained substantially below the target concentration of 10 mg/L. Except for two anomalously high readings in late April and early May, in MW-2, pre- and post-injection readings ranged from 0.2 mg/L to 4.47 mg/L. Prompted by the low DO concentrations observed in the monitoring wells, ConocoPhillips modified the shallow zone injection wells (IP-1 through IP-9) by installing diffuser tips near the bottom of each injection point. However, this attempt to correct potential short circuiting through the well screens did not bring about a substantial gain in DO concentrations, which remained significantly below the 10 mg/L target concentration. To more efficiently deliver the oxygen into the A-zone near source area well MW-2 and offsite well MW- 8, ConocoPhillips recommends abandoning and replacing IP-1 through IP-9 with A zone injection points designed to deliver oxygen to the subsurface more efficiently. Monitoring well MW-19C has a total depth of 70 feet bgs and is about 300 feet downgradient of the deep zone injection wells IP-10 through IP-12. The DO concentrations in this well also did not achieve 10 mg/L, but were slightly higher than the A-zone wells, ranging from 2.1 to 8.0 mg/L. ConocoPhillips recommends installing additional oxygen injection wells in the vicinity of downgradient monitoring wells MW-16, MW-17B, MW-18C, MW-20, MW-21B, and MW-22C. Based on the results of groundwater monitoring conducted on 26 and 27 June 2008, implementation of the oxygen injection pilot study appears to have resulted in a net decrease in concentrations of total petroleum hydrocarbons as diesel (TPHd). TPHd in MW-10, MW-16, MW-17B and MW-20 were non-detect (< 50 micrograms per liter [pg/L]) simultaneously in these four wells for the first time during the study. In addition, MW-2, MW-14, and MW-19C contained their lowest concentrations of TPHd recorded during the study. Concentration trends for other constituents, including total petroleum hydrocarbons as gasoline (TPHg), methyl tertiary butyl ether (MTBE), di-isopropyl ether (DIPE), and tertiary butyl alcohol (TBA), were stable in all pilot study wells except MW-17B, which showed slightly increasing trends for DIPE and TBA. With the exception of ferrous iron (Fe 2+), the monitored geochemical parameters show no distinct trends. Fe 21 concentrations show an increasing trend in most wells except MW-10, MW-14, and MW-19C. With the exception of MW-19C, the increasing Fe 21 trend is most apparent in the furthest downgradient wells, such as MW-16, MW-17B and MW-20, where DO concentrations were correspondingly low. Based on these results, ConocoPhillips proposes to continue the oxygen injections into redesigned A-zone and new B-zone injection wells, or alternatively to inject a stronger oxidant such as hydrogen peroxide instead of oxygen.