On Feb. 20, the Heritage Arts Centre in Hamiota was the site of a second meeting to discuss the fate of the water control structure that creates the wetland at the Pope National Wildlife Area (NWA).
Canadian National Railway (CNR) constructed the earthen dam and concrete spillway in 1926 as a water supply for the now obsolete steam engines. In 1967 CNR gave Ducks Unlimited Canada (DUC) permission to make use of the area for conservation of waterfowl and in 1974 the Government of Canada purchased the land, designating it an NWA.
The first meeting was detailed in the June 23 edition of the Empire-Advance last year where it was revealed that DUC planned to decommission the aging water control structure in the NWA. The dam is located just three miles north of the boundary between the RM of Wallace-Woodworth and the RM of Hamiota. The plans met with serious concerns from residents, landowners and municipal councils and these concerns were clearly expressed at the June meeting.
The information provided at the June session led to a commitment from DUC to improve communication with stakeholders to find an acceptable solution, and these proposals were explained at last week’s meeting.
While not showing signs of failure, the current dam does not comply with Canadian Dam Association standards and could pose a risk to critical infrastructure downstream in a failure event and it requires extensive work to satisfy safety standards. DUC deferred any proposed work to allow time to review other options and seek funding for rebuilding the structure.
Following strong public support for keeping the dam, DUC has refined the design, construction, and long-term maintenance costs. According to Parsa Arminian a conservation engineer with DUC, “Because we have a very high consequence, we have to design to something over a one in 10,000-year flood event.”
Because the nearby rail line, an essential infrastructure, would be affected by a failure of the dam in such an event, the hazard potential rating for the structure is classified as very high consequence. “So, all that is to say that we are forced to design to a standard that no one here has ever seen,” added Arminian.
Following this classification, the water control structure was designed with new hydrologic information, The old concrete spillway will be replaced with a rock spillway. The new spillway will be a similar size as the current structure and can be installed in the same location. The previous estimate for dam replacement was about $1 million over 30 years but new information and plans now place the combined rebuild and 30-year maintenance cost at $500,000.
As well as the concrete spillway there is another concrete structure and a pipe that runs through the dam to the downstream side. This structure is a concern because as the concrete ages and crumbles seepage will occur leading to erosion and eventual failure of the dam.
“Earth infrastructure gets better with age, it just gets more and more tightly packed, but concrete and steel get worse.” noted Arminian. Ron Knight who owns land near the site feels that removing this component would risk damaging the earthen dam and said, “There's loads of technology in the oil industry to use cement and plug things, and that might be a better approach.” DUC representative Shaun Greer said they “will consult third party expertise to better identify the status of this infrastructure and will use minimally invasive methods.”
The next steps in getting the renovation underway include a federal environmental assessment of the proposed rebuild and the Fisheries and Oceans Canada review process to be completed in 2024.
During the planning process DUC would look for support letters from RMs and landowners in fundraising applications. Their preferred option is to rebuild and retain the Pope NWA wetland in 2025, if funding sources or partnership can be secured. They are committed to continued engagement with landowners and RMs as the process continues.
“This is an important community asset, and we are pleased that DUC is proposing this upgrade,” said Hamiota mayor Randy Lints. “The dam and wetlands provide flood protection for landowners, the railway and our municipal roads. Even more, we have educational opportunities for local students and a natural refuge that can be enjoyed by residents and tourists.”
Wallace-Woodworth councillor Diana MacDonald attended the meeting and said, “I felt [this] meeting was more positive than the one in June. I feel that the people were heard, and that DU will do their best to rebuild the dam and retain the wetlands.”
