SITE INFORMATION AND CORRESPONDENCE

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Mr. Jeff Baker -2 - 20 August 2009 Stockton Terminals Technicommittee Since 20 September 2002, the STTC has utilized SoakeaseTM separate phase hydrocarbon (SPH) removal socks in four wells to remove SPH. The Second QMR reports that SPH or SPH sheen has recently been observed in only one of these four wells (TS-4) and in the newly installed TS-RW1. Therefore, the Soakease socks were transferred to these two wells. Consistent with historical observations, no B, C, or D zone wells contained SPH. As shown in Tables 6 and 7, during the second quarter 2009 the highest COC concentrations generally occurred in A zone wells in the BP aboveground tank (AGT) area. The highest concentrations of TPHg and TPHd were in AR/MW-8A and AR/MW-23A, respectively, at 110,000 micrograms per liter (Ng/L) each. The highest concentrations of MTBE and TBA were detected in AR/MW-50 at 10,000 pg/L and,2,500 pg/L, respectively. The highest concentration of benzene was detected in AR/MW-8A at 96,000 pg/L. The MTBE concentration in AR/MW-8A, which has been steadily increasing since 2001, was detected at 6,600 pg/L during the second quarter. This concentration is slightly lower than the previous quarter. Table 6 also includes the results of groundwater sampling, conducted in May, for methylene blue active substances (MBAS), a surfactant in fire suppression foam. Central Valley Water Board staff requested that BP conduct sampling for this parameter to assist in evaluating the effects of a November 2008 fire suppression foam release. During the first quarter 2009, samples were collected without purging AR/MW-5A, AR/MW-5C, AR/MW-13C, and AR/MW-14B in the AGT area. BP attributes historically high petroleum hydrocarbon levels in some Site wells to the fire suppression foam release. During the second quarter, BP conducted MBAS sampling in 29 wells in the A through C zones. Second quarter laboratory analytical results showed that MBAS was detected at concentrations ranging from 100 pg/L to 2,200 pg/L in these wells. The water quality objective for MBAS is 500 pg/L. To address the concentrations, BP over-purged up to 10 well casing volumes from select wells with MBAS. The field data sheets in Appendix D show that 10 wells were sampled after over-purging, including two of the wells sampled during the first quarter (AR/MW-5A and AR/MW-13C). The results in these two wells show that the MBAS concentrations decreased from the first to second quarter by about 10-fold in AR/MW-5A and by about half in AR/MW-13C. BP recommends during the third quarter to over-purge the nine wells that contain MBAS concentrations above 500 pg/L during the second quarter. Purge water is hauled offsite for treatment and disposal. In the fall of 2004, the STTC began operation of two ozone sparge (OS) systems to clean up groundwater pollution migrating downgradient from the Site. The system is comprised of 57 A zone and 16 B zone wells connected to two 5 pounds-per-day (Ibs/day) ozone generators. The OS system is divided into two portions. The west system is downgradient of Tesoro, and the east system is downgradient of BP. System performance is evaluated using an array of six remedial observation (RO) wells, two midpoint wells, and four trigger wells. Between January and March 2009, the STTC estimates that the east system and west system had run times of 79 and 83 percent, respectively. These runtimes are about 18 and 24 percent better than the previous