Borehole completion and seal testing for upper confined aquifier-monitoring wells in the 300-FF-5 operable unit

The remedial investigation of the 300-FF-5 operable unit was initiated in fiscal year 1991. A major part of the investigation involves the construction of eight new groundwater-monitoring wells in the upper confined aquifer beneath the operable unit. The upper confined aquifer has a head gradient significantly higher (approximately 30 ft) than the unconfined aquifer. Because of this, the US Environmental Protection Agency and the State of Washington Department of Ecology requested, through review comments associated with the operable unit work plan (DOE 1990), the US Department of Energy to prepare a description of borehole seal emplacement and testing for this specific operable unit. They further requested that the resulting documentation be approved by the regulatory agencies prior to constructing the first confined aquifer-monitoring well. The description of seal emplacement and testing in new groundwater-monitoring wells completed in the upper confined aquifer in the 300-FF-5 operable unit is presented in this report. This work applies only to wells drilled for the 300-FF-5 operable unit. The area under consideration is located on the Hanford Reservation. 19 refs., 19 figs., 1 tab.