The Bog: The Alberta WaterPortal Blog

The Bog is where thoughts, opinions, discussion pieces, and action converge. Influential thinkers from the water community are invited to share their insights on current or controversial water topics. Please note that the views expressed herein are those of the authors, and do not necessarily reflect the position of the Alberta WaterPortal.

Alberta Lake Management Society was formed in 1991 and works to promote understanding and comprehensive management of lakes and reservoirs and their watersheds.

The following is a summary of the report “Benefit/Cost Analysis of Flood Mitigation Projects for the City of Calgary: Glenmore Reservoir Diversion”. Please read the entire report for a full understanding of the Benefit/Cost Analysis.

The Glenmore Reservoir Diversion, also known as the Calgary Tunnel, will consist of

  • an inlet structure,
  • tunnel, and
  • outlet structure.

The cost benefit analysis assumes the structure would align with Heritage Drive in Calgary and would operate whenever a 1:10 year event or greater would occur.

Glenmore Reservoir Proposed Design Heritage Route

 The Glenmore Reservoir proposed project along the Heritage Drive alignment as drawn by Hatch Mott MacDonald.

The following is a summary of the IBI report “Benefit/Cost Analysis of Flood Mitigation Projects for the City of Calgary: McLean Creek Flood Storage” and the AMEC report “Environmental Overview of the Conceptual Elbow River Dam at McLean Creek”. Please read both reports for a full understanding of the Benefit/Cost Analysis and Environmental Review for this mitigation project. Given the simultaneous release of these reports the McLean Creek Environmental Review has highlighted new items of concern that would require additional costs, and are therefore not reflected in the IBI study.

 

The McLean Creek Dam will consist of:

  • an earth fill dam built across the main stem of the Elbow River,
  • a combined permanent outlet/spillways structure for discharging normal and flood flows and
  • an auxiliary earth cut channel spillway to protect the dam from extreme floods up to the probable maximum flood event.

 

The following is a summary of the report “Benefit/Cost Analysis of Flood Mitigation Projects for the City of Calgary: Springbank Off-Stream Flood Storage”. Please read the entire report for a full understanding of the Benefit/Cost Analysis for this mitigation project.

The Springbank Off-Stream Reservoir, as originally proposed by AMEC in June 2014, will consist of three basic components:

  • a river diversion structure
  • a diversion channel and reservoir inlet structure
  • an off-steam storage dam and reservoir

 

To accommodate a 1:100 year flood event the diversion channel will be designed to convey a peak flow of 300 m3/s.

On February 27th 2015 the eagerly anticipated Damage Assessments of the three proposed infrastructure projects for flood mitigation on the Elbow River and the McLean Creek Environmental Overview were released. The Government of Alberta released a fact sheet along with the reports.

Overall Costs of Flood Damage

The City of Calgary flood damage estimates were created though updated stage-damage curves and the Provincial Rapid Flood Damages Assessment Model. Additional information about how these damage estimates were developed can be found in the document “City of Calgary: Assessment of Flood Damages” and its appendices.

Detailed flood damage studies have not been completed outside of the City of Calgary. Areas such as Bragg Creek, Redwood Meadows and infrastructure within Rocky View County would not be protected by the Springbank Off-Steam Flood Storage project or the Glenmore Reservoir Diversion (Calgary Tunnel). To accommodate for this gap, information was taken from 2013 Southern Alberta Disaster Recovery Program and an Alberta Environment Planning Division publication from 1987 for Bragg Creek.

  • The 2013 Southern Alberta Disaster Recovery Program estimated amount for flood recovery projects between the McLean Creek dam site and the City of Calgary is approximately $5.6 million.
  • The Alberta Environment Planning Division publication from 1987 in Bragg Creek estimates damages on the order of $12.7 million would be incurred by Bragg Creek in the event of a 1:100 year flood.