This addendum to the Remedial Investigation (RI) Report on Bear Creek Valley Operable Unit (OU) 2 at the Oak Ridge Y-12 Plant was prepared in accordance with requirements under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) for reporting the results of a site characterization for public review. This addendum is a supplement to a document that was previously issued in January 1995 and that provided the Environmental Restoration Program with information about the results of the 1993 investigation performed at OU 2. The January 1995 D2 version of the RI Report on Bear Creek Valley OU 2 included information on risk assessments that have evaluated impacts to human health and the environment. Information provided in the document formed the basis for the development of the Feasibility Study Report. This addendum includes revisions to four chapters of information that were a part of the document issued in January 1995. Specifically, it includes revisions to Chaps. 2, 3, 4, and 9. Volume 1 of this document is not being reissued in its entirety as a D3 version because only the four chapters just mentioned have been affected by requested changes. Note also that Volume 2 of this RI Report on Bear Creek Valley OU 2 is not being reissued in conjunction with Volume 1 of this document because there have been no changes requested or made to the previously issued version of Volume 2 of this document.