Marseilles Hydro Plant Cofferdam

Marseilles, IL

As part of the Marseilles Hydro Plant, Ben Hur along with it’s subcontractor Lakes and Rivers Contracting completed the Downstream Cofferdam in preparation for the excavation of the Powerhouse.  The total length of the Cofferdam is 380 feet, constructed of 20 foot tall and founded on rock in the Illinois River. A temporary earthen berm was constructed in the river  to clear the rock and make way for construction. The Cofferdam is secured to the rock with 128 rock anchors, these anchors are 2″x30′ threaded rod. To anchor the rods 8″ holes were drilled into the rock, after which the rods were lowered in and the holes were filled with grout. Concrete toe and trust blocks were placed around the anchors, after which the rods were tensioned and locked off.