Drain Well Installation for PCB Removal
General Electric commissioned a polychlorinated biphenyl (PCB) cleanup project at their Hudson Falls Plant in New York State. Before PCB regulation in the 1970’s, over one million pounds of PCBs were released into the river from the production of capacitors, transformers and other devices. The project involved an innovative application of tunnel technology to remove residual contaminated PCB ground water before it entered the Hudson River. A 24-foot diameter, 200-foot deep vertical shaft was drilled to two, X-shaped, 10-foot diameter, 1500-foot long horizontal tunnels. A series of wells and horizontal drains were installed to steer PCBs into the tunnels where they would be pumped to on-site water treatment plants.
Merco Inc/Obayashi Corp
Crux provided drilling and installation services for drain wells and piezometer borings. Angle-oriented borings and drain-holes were drilled from the tunnel level, working within 10-foot diameter access tunnels.
Borings and drain-holes were completed under tight tolerances and through soft sedimentary rock. Surveys of the borehole were completed during drilling operations, and borings maintained a maximum deviation of 18 inches in each axis throughout the length of the boring. Core drilling was employed for drilling geotechnical and piezometer borings. Rotary wash drilling was employed for drain-holes. In total, 5 piezometers and 21 drain wells were installed, with depths ranging from 100 to 350 feet. Stainless steel casing was installed at each piezometer and drain-hole location.