The owner of a troubled hydroelectric dam in New Brunswick has recommended the facility be repaired rather than torn down or replaced, with an estimated cost between C$2.9 billion and C$3.6 billion.
The NB Power board of directors announced Dec. 20 it will seek permission from the provincial government to ensure the originally anticipated lifespan of the 668-MW Mactaquac hydro plant, which supplies 12% of the province's electricity customers.
"We believe we have made a sound decision about Mactaquac that makes good business sense, meets the present and future needs of New Brunswick's changing power grid and reflects the values of New Brunswickers," board Chair Ed Barrett said in a news release. "As a public utility, we clearly understand that any course of action regarding Mactaquac has deep and lasting consequences. Maintaining the station will allow NB Power future flexibility while we meet our financial and environmental goals and continue to provide safe, reliable energy at low and stable rates."
The Mactaquac hydro facility began producing power in 1968 and has suffered from a chemical reaction called alkali-aggregate reaction, which can cause concrete to swell and crack. The damage has impacted the powerhouse and spillway and has required substantial annual maintenance and repairs throughout its lifespan. The earthen dam on the St. John River, which holds back a head pond approximately 96 kilometers long, is not affected by the problem. NB Power had been faced with a decision of whether to repair, replace or destroy the facility because of the unstable concrete in the powerhouse structure. The utility had promised a decision on the matter before the end of 2016.
The new plan could extend the dam's lifespan to 2068, as was intended when the plant was built. Absent repairs or replacement, the facility was expected to have to be taken out of service early in 2030. The decision follows extensive studies of the possible environmental, social, technical and cost impacts, as well as discussions with First Nations. NB Power explained that the repairs will include extending the life of existing concrete facilities through a modified approach to maintenance and replacing equipment over time. The repairs will not require a new public river crossing.
"This option reflects the consistent support from thousands of New Brunswickers for investments in renewable electricity here at home, but not at any cost. Maintaining the station will ensure that hydro-electricity remains a critical part of our grid, which is essential to meeting our renewable energy targets today and in the future," NB Power President and CEO Gaëtan Thomas said in the news release.
The repair option, despite its multibillion-dollar cost, is the lowest-cost approach when compared to the other possibilities examined. This option also allows NB Power to take into account changes in costs, technology, electricity demand and customer priorities once the facility nears its shutdown date again in 2068.
The option to repair the dam emerged in the spring, three years after NB Power began consulting with engineers, scientists, stakeholders, the public and First Nations in 2013 on the facility's future. NB Power also explored building a new station, removing all structures except for the earthen dam and spillway, or removing all structures and restoring the Saint John River to a natural flow.
NB Power will embark on a competitive process for work related to the project, as is required by provincial legislation. It will require approval by provincial environmental officials and the province's Energy and Utilities Board for its financing.