AWARD OF EXCELLENCE: Water Structures Category

R.H. Saunders Generating Station Structural Rehabilitation

Cornwall, Ontario, Canada

Submitted by Kinectrics, Inc.

R.H. Saunders Generating Station (GS) experienced many operational and structural problems commencing in 1972. Subsequent unit inspections revealed that the generators stators and throat ring liners were deforming. In addition, the powerhouse concrete structure was deteriorating with extensive cracking, distortion and water leakage.

In 1990, an extensive engineering investigation was launched to determine the root cause of the generating equipment and structure problems. Concrete expansion due to Alkali-Aggregate Reaction (AAR) was diagnosed in 1991 as the root cause of concrete movement and ensuing generator and structural problems. Concrete and generator condition assessments, laboratory analysis, field tests, installation of numerous monitoring devices to monitor deformations in the powerhouse and mathematical modeling were utilized to establish rehabilitation needs. A proactive rehabilitation program was implemented from 1993 to 2001, to mitigate the effects of AAR-induced concrete expansion and repair the concrete structural damage.

Slots were successfully cut between the generators along the expansion/contraction joints of the concrete structure, using diamond wire technology. The immediate results were encouraging, with reduced compressive stresses in the concrete, increased runner clearances and partial rounding of the throat ring liners. Numerous innovative techniques were implemented to rehabilitate structural components that were severely damaged by concrete expansion at the powerhouse. Specially designed waterstops to control water leakage, extensive grouting utilizing a combination of epoxies, polyurethanes, polyesters, microfine and Portland cement grouts to restore structural/waterproofing integrity were used throughout the powerhouse structure.

Extensive removal and retrofitting of damaged concrete components using high-performance silica fume, fiber-reinforced, polymer-modified and high-strength repair materials and concrete were used. Installation of post-tensioned anchors and new structure corbel supports utilizing Teflon and other friction-reducing systems were installed to accommodate future movements and concrete damage. Installation of high performance coatings and sealants were applied to various concrete structures to provide waterproofing barriers and oil containment.

Owner
Ontario Power Generation
R.H. Saunders Generating Station
Cornwall, Ontario, Canada

Project Engineer/
Designer
Ontario Power Generation
Toronto, Ontario, Canada

Repair Contractor
Kinectrics, Inc.
Toronto, Ontario, Canada

Material Suppliers
Master Builders
Technologies, Ltd.
Brampton, Ontario, Canada

Concrete Restoration Services, Ltd.
Winnipeg, Manitoba, Canada