CRCAG Working Group meeting With City of Calgary Blue Ribbon Panel Head Wolf Keller and Rick Valdarchi

On November 5th members of the CRCAG working group met with Wolf Keller and Rick Valdarchi to discuss the findings and direction of the City of Calgary Blue Ribbon Panel.

This is a summary of our discussion.

Mr. Keller presented the 6 major themes the Panel is exploring.

Climates on earth have always been in a state of flux. The changes have typically happened over decades and centuries. But changes do happen. The Panel has made the determination that future understanding of our climate and any possible changes that we might be undergoing needs to be better understood. Not only for ourselves but also for generations to come.  The Panel is recommending we study and seek to understand our climate and changes to it. Some have predicted that we can expect to see more rainfall in the springs and less in the fall. Understanding around climate can help with long and short term planning for both flooding and drought events.

The entire watershed as a whole needs to be understood and we need to establish the impact that human activities have had on it. This is particularly important when seeking to understand and prevent some of the smaller flooding events such as the flood of 2005.
3.Event Forecasting.

As many of us have learnt over the past 4 months the events that lead up to the Flood of 2013 were what really could be characterized as the perfect storm. The snow pack was large and the rain was heavy and long. The Panel recognizes the need for excellent communication between various agencies. Forecasting can lead to better warning. Snow pack studies, river modeling and weather forecasting can give better predictions of potential risk.

The Glenmore Reservoir was never intended to be used for flood protection. But it did protect the City from an event more disastrous event this June. The Reservoir was brought down as much as it could be prior to the flood and as a result the peak flows were attenuated by the Reservoir.  Mr. Keller confirmed the storage capacity of Glenmore using the last survey data available was a total of approximately 17 Million Cubic Meters (10 Million Cubic Meters of active storage and 7 Million Cubic Meters of dead Storage). Mr. Keller indicated that there was a plan to increase the height of the dam by 1.5 meters which would increase the total storage capacity of the reservoir to approximately 23 Million Cubic Meters. This was an initiative that was being explored prior to the flood of 2013. If the City did this it would increase the storage capacity. Again, this option needs to be explored further to establish if this route is a cost efficient means of getting more storage. The question was asked as to whether or not dredging of the reservoir was being considered. Mr. Keller indicated that there were a number of concerns with regards to water quality and the proximity of the Weaslehead Natural area which called into question the cost/benefit of dredging.  The ongoing integrity of the reservoir is of great concern to this group and we will continue to seek clarification around this. So while the Glenmore Reservoir has some serious limitations and is nowhere near large enough to offer protection against a 2013 type flood, it did attenuate what could have been an even more devastating hit. Mr. Keller will provide CRCAG with a copy of the reservoir survey bathymetry data which is just being finalized.

One of the proposals brought forward by the Flood Advisory Panel was a subterranean By Pass.  In conjunction with upstream berming it would offer the core of the City protection by diverting flows out of the Glenmore Dam at near 58th Ave SW and, at a depth of approx 200 feet, would divert the water into the Bow River at near Deerfoot Trail. This project is within the City’s jurisdiction. Meetings with Mr. Andre Corbould verbally confirmed the Provinces financial support of the By Pass. Further designs and engineering are being undertaken. The diversion tunnel would be approximately 6 meters wide.

The City is also exploring smaller scale berming options, both permanent and temporary.

Mr. Keller clarified that Storm sewers and house sewer are generally independent systems.  It is possible that upwards of 30% of household sewage can be lost through holes in the sewer pipes.  During a flood the holes allow ground water to pressure up the sewer pipes which can cause sewage backup.
6. Infrastructure/Resiliency

The City is reviewing design standards and evaluating what changes may need to be made with regard to how we build going forward. How do we make our hospitals, schools, power stations, food supply chains etc more resilient to the risk of flooding? The City has a working group looking into the Land Use ByLaw and what changes may be advisable with regard to new buildings in the floodplain that much of the City core is on.

QUESTIONS:

We asked specifically about whether or not the City was going to dredge out the Rivers in places where there are more deposits. We highlighted specifically a place in the Elbow River where deposits have prevented the flow of water into a stream that ran behind Rideau Road. This stream was what formed the Elbow Island. The Island is now more of a peninsula.  Mr. Keller indicated that while the City understands the concerns they are reliant upon the position and rulings of the federal Department of Fisheries in this regard. It has been that departments historical position that “The River is the River” and have vehemently opposed attempts to move gravel or rocks in the riverbed.