SITE INFORMATION AND CORRESPONDENCE

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Mr. Shelby Lathrop - 2 - 3 April 2008 Former Tosco Bulk Terminal No. J13 detected in source area well MW-2 at 480 pg/L. TBA was also detected at 140 pg/L in downgradient wells MW-16 and MW-17B. The Report also describes the results of groundwater monitoring following the first in a series of planned bi-weekly source area oxygen injections. The initial series of bottled oxygen injections was implemented over four days on 17, 19, 20, and 21 December 2007 at a rate of about 13 pounds (lbs) per well per day. Oxygen was injected into nine A-zone (IP-1 to IP-9) and three B-zone (IP-10 to IP-12) injection points. The objective is to maintain dissolved oxygen (DO) levels at 10 milligrams per liter (mg/L) or greater to enhance the biodegradation of residual COCs. DO concentrations were measured in the field in monitoring wells MW-2, MW-8, MW-14, MW- 16, MW-1713, MW-19C, MW-20, and piezometers P-1 through P-6. Pre-injection DO concentrations ranged from 0.15 mg/L in MW-2 to 5.45 mg/L in P-5. Upon observing the well construction prior to the injections, SECOR believed the existing well construction was unsuitable for air injection, since oxygen injected into A-zone wells would most likely migrate upwards to the ground surface through the filter pack and thus prevent attainment of the target DO concentration of 10 mg/L. To address this problem, SECOR installed diffuser tips near the bottom of each shallow injection well. At the end of the four-day series of injections, DO concentrations ranged from 0.30 mg/L in P-2 to 5.1 mg/L in MW-17B, indicating that the diffuser tips did not significantly improve the capacity of the wells to increase DO concentrations in groundwater. Based on the results of the initial four-day injections, SECOR is considering installing additional DO injection points in the vicinity of source area wells MW-2 and MW-8 and upgradient of the well clusters MW-16/MW-17B/MW-18C and MW-20/MW- 21 B/MW-22C. ConocoPhillips proposes to review pilot test monitoring results with Regional Water Board staff after the initial 60-day test of oxygen injection capacity to assess whether the application frequency and/or application rate should be adjusted to more or less than the anticipated 13 Ib per day rate for the remainder of the 60-day test. Based on discussions with Regional Water Board staff, ConocoPhillips will determine whether an additional 60-120 days of application and/or additional well installations are appropriate. If concentrations of constituents are observed in excess of baseline concentrations, ConocoPhillips proposes to reduce or cease oxygen injections based on discussions with Regional Water Board staff. ConocoPhillips conducts groundwater monitoring at the Site pursuant to Monitoring and Reporting Program (MRP) No. R5-2004-0824. The hydrostratigraphy underlying the Site is described as consisting of three progressively deeper layers called the A, B, and C zones. The A-zone occurs at depths of about 10 to 25 bgs, the B-zone from 30 to 50 feet bgs, and the C- zone from 55 to 75 feet bgs. ConocoPhillips conducted groundwater monitoring for the fourth quarter on 30 November 2007. In the 31 January 2008 Fourth Quarter and Annual 2007 Groundwater Monitoring Report (Annual Report), the groundwater gradient and flow direction in the three zones were calculated to range from 0.03 feet per foot (ft/ft) to the southeast to 0.004 ft/ft towards the west. During the fourth quarter, the highest concentration of TPHd was 160 pg/L in MW-4. MTBE, toluene and xylene were detected below WQOs. TBA was detected at 72 pg/L in the B-zone well MW-21 B. Concentrations of TPHg, MTBE and TBA, which were once detected at