ARCHIVED REPORTS_DRAFT - PHASE I REMEDIAL INVESTIGATION REPORT

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Kennedy/Jenks Consultants 5.7.2 Trenches and Test Pits Several trenches and test pits were excavated in OU-5 during the recent characterization activities. The locations are shown on Figure 10 and the trench logs are included in Appendix B. The trenches were excavated to a maximum depth of 8 feet bgs. Analytical results from soil samples are summarized in Table 11 and Table 12, with trench samples distinguished by a "TS" modifier in the sample name (e.g., OU5-AO112-TS-8-2). 5.7.2.1 AOI 11 — Northern OU-5 Shallow test pits were excavated, as described in the Addendum, in the northern portion of AOI 11 where Geocon had previously encountered a pipeline and purple-colored soil, to delineate the extent of the purple-colored material (the "PTP-5 area"). Because of the proximity to the Kinder Morgan petroleum pipeline, a Kinder Morgan representative was onsite when excavation began. The pipeline described by Geocon and the purple-colored material were encountered in this iarea, where expected. The 3- to 4-inch thick layer of purple-colored, sandy material was encountered at about 6 inches bgs and was found in a strip approximately 3 feet wide and 45 feet long. A sample of this material (OU5-AO111-TS-4-0.5), samples of shallow soil west and east of the material (OU5-A0111-TS-1-0.5 and OU5-AO111-TS-3-0.5), and one sample of soil from beneath the material (OU5-AOl 11-TS-2-3) were collected. The samples were analyzed for lead, arsenic, PAHs, and organochlorine pesticides. MBetween this test pit and the northern border of OU-5, a small, separate area of shallow purple- colored material was unexpectedly found by kicking a shallow hole in the ground. The extent of this material (approximately 4 square feet) was delineated using a shovel because proximity to the petroleum pipeline prevented use of the backhoe. No samples were collected. The accidental discovery of this additional purple-colored material suggests the material may be widespread. 5.7.2.2 AOI 11 — Eastern OU-5 Several other test pits were excavated in the eastern portion of OU-5, in AOI 11 and the surrounding AOI 9 and AOI 12. The test pits were first excavated in the presumed area of Geocon's pit PTP-9 in AOI 11 to trace the extent of a shallow layer of coal-like material. A shallow layer of coal-like material was encountered at the first test pit, as expected, and test pits were excavated in a wider area to characterize the extent of this layer. The apparent western limit of this material was found, but the shallow layer of coal-like fragments or asphalt was found throughout the eastern portion of OU-5 as far as West 6th Street, Central Avenue, and southward to a point 25 feet north of the railroad tracks along the southeastern part of OU-5. (This layer was not encountered in soil borings in the unpaved central and western part of OU-5). A sample of the coal-like material was collected (sample OU5-AO19-TS-1-1) and analyzed for lead, arsenic, and PAHs. Sample OU5-AO19-TS-1-1.5 was collected from below the coal-like material at this location. • A shallow soil sample (OU5-A0111-TS-5 1) was collected west of the coal-like material, and four samples were collected from beneath the coal-like material at four other locations in the DRAFT Phase I Remedial Investigation Report Page 31 Former Tracy Railyard, Tracy, California g:\is-group\admin�ob\05\0565777.18_uprr\09-reports\h rpt\texldoc