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a detailed description of the previous investigations within the leasehold (SECOR, 2003). A copy of Section 2.3 of the Feasibility Study Report is contained in Appendix B for reference. SFPP Investigations. Methyl tert-butyl ether (MTBE) and petroleum hydrocarbons, including SPH, have been observed at the SFPP site since 1990. The SFPP site is located upgradient of the Facility as shown on Figure 2. In addition, a petroleum release occurred from aboveground piping in the SFPP manifold area in December 2002. The piping was subsequently repaired and soil with petroleum hydrocarbons was excavated. Additional information pertaining to the release is contained in Appendix B. SFPP is also a part of the leasehold but has not been a member of the STTC. SFPP initiated investigations in 1989 to assess the extent and distribution of SPH at its facility and to evaluate possible methods for remediation. In February 2005, Levine Fricke Recon (LFR) submitted a Cleanup Plan on behalf of SFPP recommending Monitored Natural Attenuation. Section 3.0 of the Cleanup Plan includes a description of the investigations previously performed at the SFPP facility. A copy of Section 3.0 is included in Appendix B for reference. 2.5.2 Facility Investigations, 2002 ' In August 2002, SECOR completed a comprehensive investigation (SECOR, 2003) in the areas of AST Nos. 3302, 3301, and 1503 to define the lateral and vertical extent of petroleum hydrocarbons from the previously identified releases described in Section 2.4 of this report. The investigation is described below. AST No. 3302. Five geoprobe explorations were advanced adjacent to AST No. 3302. "Fresh" SPH were observed in explorations ST/SB-1, ST/SB-2, and ST/SB-3. SPH were not identified in explorations ST/SB-4 and ST/SB-5. The explorations defined the extent of the product to the south. However, the extent of SPH was not identified to the north, east, and west of the tank. Soil samples were collected to depths up to 25 feet below grade. Soil concentrations were elevated in the 4-foot samples and decreased significantly with depth, defining the vertical extent of the release. AST No. 3301. Three explorations consisting of a geoprobe boring to 25 feet (ST/SB-6) and two hand-augered explorations to 10 feet below grade (ST/HA-1 and ST/HA-2) were advanced adjacent to AST No. 3301. SPH was not observed in the explorations. Concentrations of petroleum hydrocarbons and additives in soil were low relative to the concentrations detected in the shallow soil samples collected adjacent to AST No. 3302, indicating the fuel release did not significantly impact soil near AST No. 3301. Concentrations in the 10-foot soil sample collected at a location adjacent to the tank (ST/HA-2)were higher than the 4-foot sample,suggesting a historical release may have occurred in the area. AST No. 1503. Following the removal of fuel-impacted soil by Philip Services, soil sampling was completed from four explorations (consisting of three geoprobe borings to 25 feet [ST/SB-7 through ST/SB-9] and one hand-augered exploration to 10 feet below grade [ST/HA-3]). The explorations were completed around the Revised Cleanup Plan Page 5 NuStar Stockton Terminal-Stockton,California November Z 2012 1014-12