SITE INFORMATION AND CORRESPONDENCE

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Case File -2 - 6 July 2012 (amended 25 April 2014) Former Tosco Bulk Terminal, 3505 Navy Drive, Stockton, San Joaquin County Between 1989 and 2003, ConocoPhillips drilled 89 additional soil borings and collected soil samples. In August 2011, ConocoPhillips conducted a Human Health Risk Assessment (HHRA) and compared the historical soil data to the California Regional Water Quality Control Board — San Francisco Bay Region Environmental Screening Levels (ESLs) for commercial/industrial workers. Soil samples collected adjacent to the ALTs exceeded the ESLs for dermal absorption for TPHd, TPHg, benzene, toluene, ethyl benzene, xylenes (collectively BTEX), and methyl tert butyl ether (MTBE). These areas are covered in asphalt and direct contact with soil is limited. Figure 1 and Table 1 (attached) present the soil boring locations and concentrations. GROUNDWATER INVESTIGATION ACTIVITIES In August 1987, ConocoPhillips installed monitoring wells MW-1 through MW-3 and began quarterly groundwater monitoring. Between 1989 and 1994, ConocoPhillips installed monitoring wells MW-4 through MW-13. In December 1998, ConocoPhillips upgraded the gasoline USTs. Prior to backfilling the former gasoline UST complex, ConocoPhillips installed a conductor casing well within the UST cavity. In 1999, ConocoPhillips conducted a groundwater extraction performance test to evaluate the radius of influence during the removal of approximately 5,000 gallons of groundwater. Between January 2000 and February 2003, ConocoPhillips extracted approximately 755,000 gallons of groundwater from the conductor casing well, MW-3, MW-5, and MW-10. ConocoPhillips installed monitoring wells MW-14 through MW-22C between 2002 and 2003. In 2003, ConocoPhillips installed a GWETS and extracted groundwater until July 2006, removing about 25 pounds of petroleum hydrocarbons. In 2007, ConocoPhillips installed oxygen injection points and began injecting oxygen at the Site. ConocoPhillips injected about 9,100 pounds of oxygen into the seven injection points prior to shutting down the system in December 2010. The Site had 19 monitoring wells, including MW-1 through MW-6, MW-8 through MW-11, and MW-14 through MW-22C; MW-7 was abandoned in 1996 and wells MW-12 and MW-13 were abandoned in 2006. MW-1 through MW-6, MW-8 through MW-11, and MW-14 through MW-22C were abandoned in 2013 and 2014. Depth to water ranges from 1 to 14 feet bgs and groundwater flow is to the southwest. During the first quarter 2012 groundwater monitoring event the maximum concentrations of TPHg, TPHd, and MTBE were 110 micrograms per liter (Ng/L), 790 pg/L, and 11 pg/L, respectively. With the exception of MW-3, TPHg has not been detected above its water quality objective (WOO) since November 2009. Benzene has not been detected above its WOO in any monitoring wells since November 2007. MTBE concentrations are stable at concentrations slightly above its WOO in downgradient monitoring wells MW-16 and MW-18C; however, the remaining monitoring wells have not contained concentrations above the WOO since August 2010. TPHd concentrations remain stable in Site monitoring wells. ConocoPhillips concluded that the concentrations of TPHd and MTBE will reach WQOs in about 14 years and 10 years, respectively. In addition, ConocoPhillips estimates the remaining mass of TPHd, TPHg, and MTBE in groundwater is about 1.57 pounds, 0.12 pound, and 0.05 pound, respectively. Figure 1 and Table 2 (attached) present the monitoring well locations and groundwater data.