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Ontario Power Generation

Des Joachims GS - Dam Repair

Located 21 kilometers west of Deep River, ON, Des Joachims GS is the largest hydroelectric facility owned by Ontario Power Generation on the Ottowa River. Restoration work on the face of the dam was completed by Raven Construction in the Fall of 2006.

Raven Construction's responsibilities with respect to the dam restoration included the following:

• Supply, assemble and install an engineered cofferdam system
• Dewatering of cofferdam (24 hours per day, 7 days per week)
• Removal of deteriorated concrete from exposed dam surface and install new reinforcing steel within dam face
• Installation of 1 inch thick steel plates at dam restoration locations. Steel plates were utilized as formwork in support of concrete placement and remained in place as the permanent face of the restored dam section
• Placement of concrete at dam restoration locations

Highlights

• Being located on the Ottawa River, all work taking place was environmentally sensitive. A protective curtain was installed within the river to capture silts or debris resulting from dam demolition and/or restoration activities and all dewatering had to pass through a filter bag prior to release into the river.
• A diving company was subcontracted to support the installation of the cofferdam within the river. This required the cofferdam to be fastened to the surface of the dam and sealed off to mitigate the potential for river water to penetrate through the cofferdam once the dammed off section was dewatered.
• The structural integrity of the dam was inspected and confirmed by a certified engineer prior to the crane walking out onto the dam in support of cofferdam installation.