ARCHIVED REPORTS_DRAFT - PHASE I REMEDIAL INVESTIGATION REPORT

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Kennedy/Jenks Consultants Three of the trenches and three of the soil borings were located in or adjacent to OU-3. The soil sample collected from a depth of 20 feet bgs from Boring B8 in the southwestern portion of OU-3 contained elevated concentrations of ethylbenzene, xylenes and toluene, other alkyl ' benzenes and napthalene. Elevated concentrations of TPH compounds, but low concentrations of BTEX and other aromatic compounds, were found in the reconnaissance groundwater sample collected from this boring (Geocon 2005). Soil and groundwater samples from the other ' locations contained much lower concentrations of TPH and BTEX than the samples from Boring B8. Boring B8 was located near two reportedly inactive petroleum pipelines (Geocon 2005). VOCs, SVOCs and pesticides were generally not detected at concentrations that suggested further evaluation or remediation. 1.4.4 Operable Unit 4 OU-4 consists of a triangular parcel of approximately three acres on the northwest edge of the Railyard, bounded to the north by Sixth Street, to the east by the railroad right-of-way along Sixth Street, to the south by the railroad right-of-way that separates OU-4 from OU-3 and OU-2, and to the west by Central Avenue (Figure 2). As described in Section 1.4.3, the subsurface investigation performed by Geocon for the City included seven exploratory trenches located in or adjacent to OU-4 and seven soil borings advanced in and adjacent to OU-4. Soil samples collected from a depth of 20 feet bgs from Boring B5 in the southwestern portion of OU-4 contained elevated concentrations of ethylbenzene, xylenes and toluene. Elevated concentrations of TPH compounds, but low concentrations of BTEX and other aromatic compounds, were found in the reconnaissance groundwater sample collected from this boring (Geocon 2005). The other reconnaissance groundwater samples collected from OU-4 contained relatively low concentrations of TPH and BTEX compounds. 1.4.5 Operable Unit 5 OU-5 consists of approximately 22 acres bounded on the north by Sixth Street, on the east by Central Avenue, on the south by railroad right-of-way running parallel to Fourth Street, and on the west by railroad right-of-way generally parallel to Tracy Boulevard (Figure 2). Based on review of Union Pacific's station map for OU-5 and the Environmental Assessment, Tracy Station Property(ESA) prepared by Geomatrix Consultants (2001) on behalf of Union Pacific, past OU-5 improvements include railroad right-of-way and right-of-way maintenance areas. The station map shows a series of packing sheds located on OU-5, but activities associated with those structures were unknown. The station map also shows street right-of- ways and residential lot boundaries, but there has been no indication that this development ever occurred. Other buildings previously located onsite included an unidentified building, signal repair building, express building, yard master's office, bunk house, Robert's Warehouse, and Fabian Warehouse. Underground utility pipelines shown on the station map include water and DRAFT Phase I Remedial Investigation Report Page 8 Former Tracy Railyard, Tracy, California g:lis-groupladminl o610510565777.1 B_uprr109-reportsl6 rptltextdoc