This report summarizes the well installation, plugging and abandonment, and redevelopment activities conducted during the federal fiscal year (FY) 1998 at the Y-12 Plant, Oak Ridge, Tennessee. Five new groundwater monitoring wells were installed at the Y-12 Plant under the FY 1998 drilling program. Two of the wells are located in west Bear Creek Valley, one is in the eastern Y-12 Plant area near Lake Reality, and two are located near the Oil Landfarm Waste Management Area, which were installed by Bechtel Jacobs Company LLC (Bechtel Jacobs) as part of a site characterization activity for the Oak Ridge Reservation (ORR) Disposal Cell. Also, two existing wells were upgraded and nine temporary piezometers were installed to characterize hydrogeologic conditions at the Disposal Cell site. In addition, 40 temporary piezometers were installed in the Boneyard/Bumyard area of Bear Creek Valley by Bechtel Jacobs as part of the accelerated remedial actions conducted by the Environmental Restoration Program. Ten monitoring wells at the Y-12 Plant were decommissioned in FY 1998. Two existing monitoring wells were redeveloped during FY 1998 (of these, GW-732 was redeveloped tsvice). All well installation and development (including redevelopment) was conducted following industry-standard methods and approved procedures from the Environmental Surveillance …