ARCHIVED REPORTS_DRAFT - PHASE I REMEDIAL INVESTIGATION REPORT

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Kennedy/Jenks Consultants northern, southern, eastern, and western portions of eastern OU-5. These are samples OU5-AO19-TS-2-3, OU5-AO19-TS-4-2, and OU5-AO19-TS-3-3, and OU5-AO19-TS-1-1.5, respectively. In accordance with the Addendum, these samples were analyzed for lead, arsenic, and PAHs. These sample locations are shown on Figure 10. 5.7.2.3 AOI 12 As shown on Figure 10, one test pit and three trenches were excavated in AOI 12. The trench logs are included in Appendix B. The test pit was located in the northeast part of AOI 12 where the geophysical locators identified an underground object. An 8-inch diameter metal pipeline was uncovered in this test pit at a depth of about 1.5 feet bgs. No backfill was evident and no discoloration or other evidence of chemical impact was visible around it. Sample OU5-AOI12-TS-1-3 was collected from below this pipe and analyzed for lead, arsenic and PAHs. This sample contained lead at 13 mg/kg, arsenic at 5.9 mg/kg, and PAHs were not detected at concentrations exceeding analytical reporting limits. Three longer trenches were excavated in central AOI 12, to locate two pipelines uncovered by ' Geocon in 2004 in AOI 10: a wooden oil pipeline discovered at approximately 16 inches bgs and metal pipeline surrounded by oily backfill at approximately 8 feet bgs. These pipelines are described in a letter from Geocon to Surland Companies dated 25 August 2005. The first and easternmost trench excavated was 420 feet long. As shown on the trench log in Appendix B, the southern 320 feet of this trench was excavated to a depth of 5 feet bgs and the northern portion was excavated to 8 feet bgs. The central and western trenches were arranged parallel to the eastern trench, at about 65 feet spacing from each other. The central and western trenches were both 8 feet deep; the central trench was 75 feet in length and the western trench ' was 42 feet in length. Several pipelines were uncovered in the trenches, including several shallow clay-tile pipes, a shallow metal pipe, the shallow wood pipe, but the deeper metal pipe was not encountered (see Appendix B). The wood pipe matched Geocon's description: 8-inches diameter, made of wood, filled solid with black soil, and surrounded with a coiled wire. The wood pipe was extremely decomposed. The soil immediately surrounding the pipe was dry and black in color without odor. The wood pipe was encountered in the three trenches and samples were collected from beneath the pipe in each trench (samples OU5-AO112-TS-4-2.5, OU5-AO112-TS-5-2.7, and OU5-AO112-TS-7-3). Sample OU5-AO112-TS-4-1.3 was collected adjacent to the wood pipe. These samples were analyzed for TPHg, BTEX, TPHd, and TPHmo. ' The projected path of the wood pipeline is shown on Figure 10 through Figure 15. The projected path is based on where the wood pipeline was encountered in this investigation, and the estimated location of Geocon's test pit GT-2. A distinct lens of black, discolored material was exposed in the face of the westernmost trench about two feet from the wood pipe. This black material was hard and broke into conchoidal fragments with a waxy luster. A sample of this material was collected (OU5-AOI12-TS-8-2) and analyzed for TPHg, TPHd, TPHmo, and PAHs. Page 32 DRAFT Phase I Remedial Investigation Report Former Tracy Railyard, Tracy, California g11s-groupladminGoh10510565777.16_uprrl0g-reportsld rpMext.doc