Barge Supported Core Drilling
The Dalles Dam located on the Columbia River 2 miles east of The Dalles, Oregon. The US Army Corps of Engineers planned to install a fish guidance system in the forebay of the dam to prevent fish from entering the water intake. The purpose of the project was to contribute to an environmentally friendly practice while simultaneously ensuring intake water quality.
US Army Corps of Engineers
Cornforth Consultants Inc.
The project involved drilling in water depths up to 105 feet and with currents of up to 3 feet per second. One third of the boreholes were located in active shipping lanes with water level fluctuations of up to 5 feet per setup. Permissible tolerance for borehole location was +/- 5 feet.
Crux designed and assembled a 40-foot by 18-foot barge from which drilling operations were conducted. The barge anchoring system included electric winches, each with a spool capacity of 500 feet. Due to the strong current and in order to provide additional support to the free-length portion of the drill string, technologies were integrated into the barge design to minimize the drift of the drill string.
Crux-designed technology and methodology insured the verticality and stability of the free length of the drill string above mudline. HWT casing was advanced into competent rock, and HQ core was recovered for a further 40 feet. Packer testing and Crux Oriented Borehole Logging (COBL) optical televiewer surveys were also conducted in most boreholes.