Unit overhauls underway at Otto Holden GS to ensure reliable, clean power

In eastern Ontario, on the Ottawa River, work is underway to ensure decades more reliable, clean power from OPG’s 70-year-old Otto Holden Generating Station (GS).

The 243-megawatt facility is just one of many hydro stations in OPG’s fleet set to undergo refurbishment as part of the company’s $2.5-billion turbine/generator overhaul program, which will span more than 20 years.

This is necessary to ensure the province’s long-serving hydro stations can continue to keep powering Ontario while helping to achieve a net-zero carbon future, as outlined in OPG’s Climate Change Plan.

At Otto Holden GS, work began in June 2021 to overhaul the plant’s Unit 7, which is expected to be back in service sometime in spring 2022. By 2029, all eight of the station’s units will have been refurbished and, in the case of Units 1 to 4, upgraded to improve efficiency.

“The work going on at Otto Holden encapsulates a typical unit overhaul,” said Harvey Sefton, Trades Management Supervisor at OPG. “With Unit 7, we completely disassembled the moving parts, machined certain components, and upgraded the unit to improve reliability, longevity and reduce environmental risks.”

Back in 1952, when it first went into service, Otto Holden GS was one of several new hydro stations built on the Ottawa River to help meet the rapidly growing power demands of southern Ontario.

It was the third station in two years placed into operation on the river by OPG’s predecessor, Ontario Hydro, and the 13^th new generating station in the company’s great post-war expansion program.

Originally called La Cave Generating Station, the plant was renamed to honour Dr. Otto Holden, an accomplished engineer with Ontario Hydro who was instrumental in the expansion of hydroelectric power in the province.

For the current overhaul, external contractors are executing much of the work, with OPG staff providing support and oversight. Millwrights, carpenters, electricians, pipefitters, and general labourers have all been employed on the project, and many more skilled trades will be needed to complete similar overhauls in the coming years.

The Otto Holden project is also leveraging expertise across OPG as the company’s Niagara Falls work centre and its complex machining equipment helped complete repairs on the Unit 7 runner while the Dymond work centre machined the unit’s wicket gates.

In addition to the unit overhauls, the project team at Otto Holden will be upgrading the original headgate controls from 1952 to modern standards.