ORCA Unveils Preferred Dam Design

Karen Graham

At the Information session hosted by ORCA on Tuesday, host Marinigh and Senior Project Manager Alfred Breland of consulting firm Hatch Ltd. outlined some of the issues that will be addressed in the Addendum to the Environmental Study to bring the Millbrook Dam Reconstruction project in line with new flood and earthquake standards and address rising sediment levels in the reservoir. Hatch is an employee-owned engineering consulting firm based in Mississauga, Ontario with 300 dam safety assessments performed in the last 15 years for clients including the Ministry of Natural Resources and Forestry, Conservation Authorities and other municipalities.

There will be a few change at this location with ORCA’s proposed Dam design, but they will not be as significant as originally feared. They even leave room for a relocated Mill! Photo: Kathie Lycett

There will be a few change at this location with ORCA’s proposed Dam design, but they will not be as significant as originally feared. They even leave room for a relocated Mill! Photo: Kathie Lycett

ORCA tabled three construction options from option A, the spillway removal and channel restoration, option B, the spillway removal with an off-line pond, and the preferred option C, the spillway retention and headpond retention. This last option involves the construction of a 30m ogee crest weir and a hardened embankment dam, which is slightly narrower than the original projection of a 36m wide construction. This option increases the dam’s capacity to the required Inflow Design Flood rate of 181 cubic metres per second…

The public has the opportunity to provide comments on this project until November 19th. The complete presentation content is available on ORCA’s website at www.otonabee.com , under the Conservation Projects banner. Comments can be submitted via email tootonabeeca@otonabee.com , by Fax at 705-745-7488 or by mail to Otonabee Conservation, 250 Milroy Drive, Peterborough, Ontario, K9H 7M9.

After this period of review, the Addendum is expected to be filed early next year with project approval anticipated for March 2016.

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