GAAT dry well conductivity monitoring report, July 1997 through January 1998, Oak Ridge National Laboratory, Oak Ridge, Tennessee

A waste removal program is being implemented for the Gunite and Associated Tanks (GAAT) Operable Unit at Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee. The waste is being removed by means of remotely operated, in-tank, confined sluicing equipment. The waste removal operations in Tanks W-3 and W-4 in the North Tank Farm (NTF) have been completed and the equipment is being moved to the South Tank Farm (STF), where it will be used to remove the sludges from the six STF tanks (W-5, W-6, W-7, W-8, W-9, and W-10) beginning later this year. During sluicing operations the dry wells adjacent to each of the tanks are instrumented so that potential releases can be detected by means external to the tank. The method of detection is by monitoring the electrical conductivity of the water in the dry well associated with each tank. This report documents the dry well conductivity monitoring data for the period from July 1997 through January 1998. The dry wells monitored during this period include DW-3, DW-4, DW-8, DW-9, and DW-10. The conductivity of the water passing through Pump Station 1 (PS 1) was also monitored. The principal activities that occurred during this period were the sluicing of Tanks W-3 and W-4 in the NTF, transfer of tank liquids from the NTF to the STF, and the installation of new risers, tank dome leveling, and emplacement of stabilized base backfill in the STF. Presented in this report are the dry well conductivity, rainfall, tank level, and STF construction information that is relevant to the analysis and interpretation of the monitoring data for the reporting period. A thorough analysis of the monitoring results for the period indicates that no releases have occurred from the gunite tanks being monitored