SITE INFORMATION AND CORRESPONDENCE

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Mr. Jeff Baker 2 0 18 September 2008 Stockton Terminals Technical Committee entrations typically underlie the BP and Time Oil wells contained SPH. The highest COC conc facilities. During the second quarter 2008, the highest COC concentrations were generally in A zone wells on the Time Oil property. The highest concentrations of TPHg and PHed were in AR/MW-8A and TO/MW-1 at 88,000 micrograms per liter (Ng/L) and 130,000 pg/L,ell AR/MW 86. The highest concentration of TBA, however, was in the B zone at 2,500 pg The OS system is divided into two portions. The west system is downgradient of Tesoro and the east system is downgradient of BP. Between March and June 2008, the STTC estimates that the east system and west system had run times of 62 and 93 percent, respectively. The STTC estimates that collectively, 374 pounds of ozone were injected and 120 pounds of hydrocarbons were destroyed during this period. The STTC conducts an OS system monitoring program in four A and B zone remedial trigger wells (OW-2A, OW-4A, OW-2B, and OW-4B). A contingency plan is triggered if the concentrations of BTEX or MTBE in any of these wells exceed California primary MCLs for these compounds. BTEX and MTBE concentrations in the trigger wells were below reporting limits during the second quarter 2008. During a 5 June 2008 meeting, Regional Water Board staff and STTC agreed that I and Mr. Gary Haeck of Stantec would work together to clarify and update the eer contingency plan and optimize 9 monitoringstem 10 ep September,, I ogram. ema I dur 30 Jthe Reg ouly 2008 lnal Water requested the updated plan by September. Ptember. On Board staff's suggestions for optimization of the OS system monitoring program and verbally reminded Mr. Haeck of this on 15 September. Mr. Haeck assured me that Stantec's suggested revisions to the OS monitoring program are being prepared for submission as agreed. Stantec will summarize the proposed changes to the OS system monitoring program in a separate letter after they have been formulated. The Schedule proposes to destroy and relocate monitoring wells OW-3C, OW-3D, and PS/MW- 20A because they were buried by a recycled building materials plant. In addition to these replacement wells, STTC will install three new monitoring wells (PS/MW-20B through PS/MW- 20D) near the location of PS/MW-20. The Schedule estimates that drilling will commence the week of 15 September and will take about three to four weeks to complete. The Schedule proposes to submit a well installation report by mid-December. TS/MW-3D will be installed on the Tesoro site during the same mobilization. In our 18 September 2008 letter to Tesoro, Regional Water Board staff concurred with the work plan for this well installation. Our comments are presented below. 1 . Regional Water Board staff concurs with the abandonment and relocation of OW-3C, OW-31), and PS/MW-20A and the installation of PS/MW-20B through PS/MW-20D, as described in the Schedule. STTC needs to submit a well installation report by 15 December 2008. 2. The west OS system run time of 93% is a significant improvement over the performance recorded during the previous quarter. In comparison, the Second QMR documents that between April and June, the reported 62% run time of the east OS system can be attributed to either continued ozone leaks or a malfunctioning ozone leak sensor during April and May. During late May and June, however, Table 8 shows that run time increased to about 100%.