SITE INFORMATION AND CORRESPONDENCE

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adequately defined so that cleanup can be planned and implemented. Other potential on-site contamination will be addressed in the future site-wide comprehensive RI/FS. nI) 5MUud6s, heavy M6 a onto owtrr0rJur1C�_� Four alternatives were examined for cleaning up the groundwater in OU #1. This Proposed Plan describes each alternative and sets forth DDRW-Tracy's and the regulatory agencies' reasons for choosingA preferred alternative. DDRW-Tracy solicits your comments, since its ultimate choice may be different from the preferred alternative described in this Proposed Plan if new information or comments submitted during the comments period suggest changes. Please comment not only on the preferred alternative but on all the other described alternatives, as well. See the box on the next page for the date and location of a public meeting and also for where to send written comments. The public comment period begins date 1992, and continues through date 1992. The preferred alternative for DDRW Tracy OU #1 cleanup is to extract groundwater using pumping from wells and then to treat the extracted water by air stripping, a method of removing the PCE, TCE, and other organic contaminants from groundwater using air as a "stripping" force. In addition, the air carries the contaminants through an air emissions control system (using vapor-phase carbon) to trap them on carbon instead of releasing them to the outside air. Treated water will then be injected back into the aquifer. Environmental studies conducted to date concerning OU #1 at DDRW-Tracy are contained in draft reports for remedial investigations/feasibility studies (RI/FS), which are now available for public review and comment. These reports are the Operable Unit No. 1 Remedial Investigation, Risk Assessment, and Feasibility Study. These reports and other documents associated with OU#1 constitute the "Administrative Record." This Proposed Plan highlights S key information from these reports but is not a substitute for the detailed discussion contained 77 within them. The draft RI/FS reports for OU #1 present and describe data collected at DDRW-Tracy and develop and evaluate possible measures, called remedial alternatives, to address environmental -(n� contamination that has been identified. Information about these reports may be obtained fru raj the Tracy Branch of the Stockton-San Joaquin County Public Library and from the Environmental Protection Office of DDRW-Tracy. Complete addresses, telephone numbers, and contact names are listed on pages 16, 17, and 18. QVW043.1(90380Cr3 3 M1007921606