innovative foundation design transforms unusable land into wind farm
While conducting a geotechnical investigation at Iberdrola Renewables’ Casselman wind-power project site in Pennsylvania, Barr discovered mine spoils (loose rocks and soil excavated during coal mining) under eight proposed turbine locations. Mine spoils are prone to subsidence and can be geologically erratic, seemingly unsuitable beneath top-heavy structures like wind-power turbines that need very stable foundations.
Charged with developing an engineering solution to mitigate risks posed by the mine spoils, we adapted micropile foundations for a wind-turbine foundation design that was the first of its kind. For each foundation, twenty-four micropiles extend through the spoils and anchor in bedrock 100 feet under ground.
The Casselman wind-power project is now on line, and what was once considered an unusable tract of land is generating enough power for 10,000 homes. The Minnesota Society of Professional Engineers recognized Barr’s deep micropile wind-turbine foundation as one of its annual “Seven Wonders of Engineering," and we've designed similar foundations for other wind-power sites where mine spoils are present.