Millbrook Dam Project Underway

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Photo Karen Graham.
Heavy equipmeht pushes steel plates through frozen ground at the dam site in early February.

The pounding of steel on steel has been providing background music to the downtown area for the past few weeks as the dam reconstruction project began in earnest.

The sounds came from the installation of sheet piling to establish an open creek channel to divert water away from the existing dam and build temporary coffer dams.  To expedite the process, Council passed a motion to allow the noise to proceed outside regular hours, including weekends.  Hopefully neighbours will associate the construction sounds with progress rather than nuisance.

Pond water levels are being lowered as the water begins to flow through the diversion channel, and eventually all water will stop flowing through the existing concrete spillway and move only through this route.  The lowering of the pond level will result in extremely dangerous and unpredictable ice conditions, so the public is warned to avoid the area.

Once the water level is reduced, the contractor will begin to remove the existing concrete, wood and sheet pile spillways as well as the U-shaped weir and steel bridge.  Construction of the new, 12 meter wide spillway is scheduled to begin in April, and will be undertaken in a single phase.  The new spillway and stilling basin will be formed from reinforced concrete.   The floor of the spillway has been designed to address geo-technical issues of the site; these design features will not be visible to the viewer as they are below ground and underwater. The new weir will be a U-shaped weir with outside wall dimensions of 5 meters by 16 meters by 5 meters.

The fourth and final phase of the construction project will involve the removal of the coffer dams and the installation of hardscaping on the earthen embankment of the dam.  At the project’s completion, the size and water level of the mill pond will remain return to its historical level and the waterfall sights and sounds will be very similar to original conditions.  The final stage will be the reinstallation of a public walkway over the dam and some landscaping around the dam.

The new dam will not only provide a familiar and welcome gathering spot for the community somplimented by the newly-renovated Needler’s Mill, but will also offer increased flood protection for the village.  Water movement is subject to new monitoring protocol to measure current flows against the dam’s hydraulic capacity every six hours to ensure the early detection of problems.  ORCA notes that even during the floods of early February, water flow remained well below capacity.

This is by far the largest capital project undertaken by the Otonabee Regional Conservation Authority (ORCA), and they expect the construction to be completed by October.  While the project was made possible by joint federal and provincial funding of $2.2 million, the township remains on the hook for the remaining $1.2 million plus the cost of sediment removal which will occur while the water level is lower, estimated at another $350,000.  To keep track of the project, Council has asked ORCA Chief Administrative Officer Dan Marinigh to provide them with a monthly status report.  In his February report, Marinigh stated it was currently on time and on budget.

After more than 12 years of studies and discussions, ORCA Board Vice-Chair Sherry Senis is among the many stakeholders who are pleased to see the project finally launched.  Collaboration between all tiers of government has made this possible, and the investment in this historical, cultural and socially important piece of local infrastructure will benefit the community and its residents for many years to come. KG

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