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SECTIONONE Introduction <br /> URS Corporation (URS) has been retained by Dow Chemical Company (DOW) to conduct a soil <br /> gas survey of their facility in Tracy, California (Figure 1-1). This work was requested by the <br /> California Regional Water Quality Control Board (RWQCB) Central Valley Region (CVR) in a <br /> letter dated July 9, 2003. The investigation will consist of the advancement of four soil gas <br /> probes in the vicinity of the rail spurs located on the western side of the Dow facility (formerly <br /> owned and operated by the Celotex Company). <br /> A project-specific Health and Safety Plan (HSP) was developed for previous work conducted at <br /> the site. The HSP identified potential site hazards, and specifies procedures for reducing the risk <br /> of accidents or injuries, and responding to emergency situations. All site personnel will review <br /> the HSP prior to initiation of this work. URS and subcontractors will perform work in a safe <br /> manner, in accordance with applicable Occupational Safety and Health Administration (OSHA) <br /> health and safety requirements. <br /> 1.1 BACKGROUND <br /> The subject site was previously owned and operated by the Celotex Company, who <br /> manufactured rigid insulation board from 1980 to 2001. Dow purchased the facility and is <br /> continuing the manufacturing processes. Prior to the sale transactions, Celotex retained two <br /> environmental consulting firms to perform Phase I and Phase II Environmental Site Assessments <br /> (ESAs) on their behalf. The Phase I ESA was performed by Environmental Resources <br /> Management (ERM) in November 2000 (ERM, 2000). The Phase II ESA was performed by <br /> O'Brien & Gere Engineers, Inc. (OBG) in June 2001 (OBG, 2001). During the Phase II ESA, <br /> six surface soil samples were collected and analyzed for volatile organic compounds (VOCs) and <br /> metals. Results indicated 17,000 micrograms per liter (µg/L) of methylene chloride were present <br /> in a surface soil sample collected near the rail spur on the western side of the facility. Based on a <br /> review of the investigation, data gaps existed that warrant an additional assessment on behalf of <br /> DOW. URS conducted the additional assessment in 2002. <br /> URS conducted four cone penetrometer tests (CPTs), collected eight soil samples, installed four <br /> monitoring wells and collected groundwater samples. Results of those investigations indicated <br /> very low levels (below all regulatory limits) of VOCs were present in the soil and groundwater. <br /> Based on the results of the URS investigations, the RWQCB requested a soil gas survey be <br /> conducted. <br /> UMVADovACeloteASoil Gas WRSoil Gas WP.doc 1-1 <br />