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1.0 INTRODUCTION 1.1 GENERAL INFORMATION This Remedial Investigation (RI) Report, hereinafter referred to as the "Report," was prepared by Parsons on behalf of Pacific Gas and Electric Company (PG&E) to document remedial investigation activities conducted at the former Tracy Manufactured Gas Plant (MGP) site located at 502 East Grant Line Road in Tracy, California(Site). Site investigation activities were conducted in two separate phases: Phase 1 was implemented in July/August 2008 as outlined in the Remedial Investigation Workplan (Parsons, 2008); and Phase 2 was conducted in April 2009 to fill data gaps identified during the Phase 1 investigation activities as documented in the Final Technical Memorandum - Supplemental Site Investigation for the Delineation of Data Gaps Identified During the Remedial Investigation (Parsons, 2009). This Report is being submitted by PG&E to the State of California Environmental Protection Agency (Cal/EPA), Department of Toxic Substances Control (DTSC) to comply in part with the Voluntary Cleanup Agreement (VCA), Docket No. HSA-VCA 07/08-072, issued by the DTSC to PG&E on October 12, 2007 (DTSC, 2007). This VCA is presented in Appendix A. The DTSC is authorized to review, evaluate, and approve documents such as this Report under the California Health and Safety Code (CH&SC), Chapter 6.8 Section 25187, which was developed to carry out a removal action in an effective manner that is protective of the public health and environment. In addition, Iris Environmental has been contracted to Parsons' to conduct a Human Health Risk Assessment (HRA) for the Site, which will be provided, under separate cover, and incorporated into one streamlined HRA/Removal Action Workplan (RAW) document. The purpose of the HRA will be to: 1) characterize the potential cancer risk and non-cancer hazard posed by the presence of chemicals at the Site under current and potential future land-use scenarios; and 2) identify the particular chemicals and areas of the Site that contribute most significantly to the risks that may require some form of remedial response. 1.2 PURPOSE AND OBJECTIVE The primary purpose of this Report is to document the sampling and analysis program implemented at the Site, which was designed to further define the lateral and vertical extents of impacts from the former MGP Site operations; and secondarily to assess the potential releases associated with a former gasoline underground storage tank (UST). The object of this Report is to present the results of the recent RI and Supplemental Site Investigation (SSI) activities, and to determine the disposition and significance of the Chemicals of Potential Concern (COPCs) at the Site. 1.3 PUBLIC PARTICIPATION ACTIVITIES A community survey was prepared and submitted to DTSC for review, comment, and approval prior to the implementation of the remedial investigation activities conducted at the Site. Upon approval, the community survey was distributed to the persons/businesses outlined in the community survey. Per the VCA (Appendix A), a Public Participation Plan was prepared and PARSONS 7 FINAL RI REPORT-FORMER TRACY MGP APRIL 2010