Karst Evaluation of a 90-Mile Transmission Line

Prior to construction, a geotechnical evaluation was conducted of the 90-mile long Wyoming to Jackson's Ferry 765 kilovolt electrical transmission line that included almost 60 miles in the section on the southern end of the line that could be underlain by carbonates. The evaluation concentrated on the planned tower locations along the 200-foot wide corridor through southern West Virginia and western Virginia. It was determined that 40 of the 219 tower sites in that section were underlain by formations where significant karst could be anticipated. The work included compiling the geology for the entire corridor and identifying the potentially karst forming formations. Field reconnaissance, drilling and geophysics (electrical imaging) was conducted to determine site conditions. Potentially affected towers were moved or replaced with multiple structures in areas where karst features could directly impact the stability of a tower or where construction could affect the karst system. Abandoned surface iron and manganese mines were also encountered during the work.