A multi-year study by GRCA staff of updated technical guidelines for dam regulation in Ontario could mean an emergency spillway may not be needed for the Conestogo Dam after all.
The GRCA has been studying the idea of constructing a spillway for years, going back to a 1997 dam safety study that identified deficiencies to the dam’s spillway capacity.
Originally, a cost estimate of over $20 million was placed on the project, which was to involve constructing a channel around the dam to re-direct water into the river.
When new regulations were introduced in 2011, GRCA officials originally hoped they would mean a spillway could be built at reduced cost.
However, a report presented for information by GRCA director of engineering Dwight Boyd at the Aug. 22 GRCA general meeting explains the new regulations mean the spillway may not have to be built at all.
In 2009 the Ministry of Natural Resources (MNR) granted GRCA permission to upgrade the stilling basin at Conestogo Dam.
The permission included a condition that an emergency spillway be constructed by Dec. 31, 2015.
Correspondence was received from MNR on Oct. 11, 2013 extending the deadline to construct an emergency spillway to Dec. 31, 2018.
This extension was granted to provide additional time to assess the need for the spillway.
In Ontario, dams are regulated under the Lakes and Rivers Improvement Act, which is administered by MNR.
On Aug. 24, 2011 the province released new technical guidelines for approval of projects under the Lakes and Rivers Improvement Act.
“The new technical guidelines have implications to the need for an emergency spillway at Conestogo Dam,” states Boyd in his Aug. 22 report.
“Staff have been working with MNR staff over the past three years to evaluate the impact of the new guidelines on the emergency spillway project.
“Preliminary indications suggest an emergency spillway may not be required; supporting technical information is being finalized based on feedback and additional technical questions from MNR staff.”
Boyd said additional technical information will be finalized over the fall and a meeting will be held with MNR staff later this year to conclude the assessment or to identify any remaining questions or concerns.
“The extension granted by MNR is intended to provide additional time to assess the need for an emergency spillway. The five-year budget forecast will be amended when additional information becomes available.
“For now, no allowance has been included in the forecast for construction of an emergency spillway,” Boyd explained.
