SITE INFORMATION AND CORRESPONDENCE

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No Further Action Required Determination - 3 - 19 November 2009 Former Lyoth Loading Station •Lyoth Offsite 12 to 20 feet bgs. Soil and groundwater samples were collected and analyzed for TPH compounds. The results of the 102 soil samples submitted for analysis reported TPHc from ND to a maximum concentration of 70,000 milligrams per kilogram (mg/kg) in a sample from a depth of 13 feet bgs. All sample results for BTEX were ND and the PAHs were ND except for four results that were at or slightly over respective method detection limits (MDLs). TPH analysis for the majority of the remaining soil samples from depths between 13 and 25 feet bgs generally were ND. Eighteen groundwater samples were collected for TPHd, BTEX, and PAH analysis. Groundwater samples were not collected from the boring that was developed into monitoring well (MW)-2 where separate-phase crude oil was reported in soil and groundwater. Concentrations of TPHd in groundwater ranged primarily from ND to 4,900 micrograms per liter (pg/L) with 66,000 tag/L detected in one sample. The latter sample also contained total recoverable petroleum hydrocarbons (TRPH) at a concentration of 120,000 pg/L. The majority of the BTEX and PAHs analytical results were ND with the exception of some detections reported with the samples containing elevated TPHd and/or TRPH concentrations. • During 1999 Chevron's consultant completed and submitted a health risk assessment (HRA) for future site residents (on the former Lyoth facility) to OEHHA staff for review and determination of risk using a residential land use scenario for an adult/child. Risks were estimated for a reasonable maximum exposure scenario based on highest detected concentrations of the chemicals of potential concern - BTEX and PAHs identified by the earlier investigations. According to OEHHA's findings, the results indicated that there should be no unacceptable risk to future residents and concluded that no remedial action was necessary to make the site protective of human health under the scenarios evaluated. The hazard index (HI) for the areas of affected soil/groundwater is below 1. • In 2002, an addendum to the 1999 HRA was submitted to provide additional inhalation pathway information on concentration of benzene in one sample that was detected in shallow soil. The total risk determination was virtually unchanged and OEHHA concurred with the previous findings that the exposure risk remained as generally within a range of risk management and the findings were approved by OEHHA staff. Central Valley Water Board staff concurred in June 2006 and June 2007, respectively for both properties, that additional characterization was not needed. • Quarterly groundwater monitoring was conducted at the project beginning in 1997, semiannually starting July 2002, and annually from August 2007. Groundwater monitoring was discontinued in July 2008. In June 2009 Central Valley Water Board staff concurred with a workplan for destruction of the six groundwater monitoring wells. • SAIC provided a No Further Action Required Request Report (NFAR) for closure in May 2008. The NFAR included documentation of site conditions in accordance with the 16 April 2004 Appendix A — Tri-Regional Board Staff Recommendations for Preliminary Investigation and Evaluation of Underground Storage Tank Sites, Section 6.5 NFAR for Cases Exceeding Water Quality Objectives. • An environmental risk evaluation (ERE) dated January 2009 completed by SAIC for the Lyoth Offsite property determined that the potential exposure pathway to future residents/commercial workers is incomplete. In addition, the petroleum hydrocarbon