Okotoks - Flood proofing recommended

Alberta Environment suggests only minor changes at meeting

By Laurel Nadon
Staff Reporter

Minor changes may be needed in the flood fringe area was the message from Alberta Environment at a flood analysis meeting at the Foothills Centennial Centre on Monday.
As for what could have been done to prevent the damage caused by the June disaster, which has been identified as a 1:100 year flood, the response from provincial officials was everything was handled properly.
“There’s really nothing that could have been done differently,” said Erin Gregg, spokesperson for Alberta Environment. “We can’t control what Mother Nature does, but we can try to protect people as much as we can.”
Approximately 55 residents attended to hear about the flood analysis from the June floods and what changes were recommended to prevent a similar disaster.
Chandra Mahabir, river engineering team leader for Alberta Environment northern region, said that no alterations are planned for the flood fringe area on the north side of the tracks in Okotoks.
Mahabir reported that there were no significant overtopping flows at railway tracks in the study area, which is based on high water marks. Water was observed to be within 0.3 metres of overtopping the tracks through Okotoks. Alberta Environment recommends minor adjustments to the fringe area around Northridge Drive after a storm sewer analysis by the town.
“We’re recommending flood proofing on the other side in case it goes over the top (of the tracks),” Mahabir said.
Water level monitoring stations are currently located on the Sheep River at Black Diamond and on Three Point Creek at Millarville. A new water gauging station on Northridge Drive will also be in place by October 2006.
Frank Callaghan, who lives in Medicine Hat and owns Okotoks Country Inn, expressed concern that by the time the town has some answers, another year will have passed and there could be another flood before anything is changed.
Alan Pentney, regional approvals manager for Alberta Environment southern region, said the town can look at their storm sewers, ensure development is controlled in the flood fringe areas and keep the CPR berms the same.
“If you develop in those flood fringe areas, it makes it worse in other areas,” Pentney said.
He noted that sometimes in floods, residents ask for berms near their homes, but this could negatively impact other areas.
When asked about the significant of the event, Pentney responded, “It’s not significant when you compare it to (Hurricane) Katrina.”
Sylvia Schunicht, who lives on Oak Avenue, asked if Alberta Environment knows if there will be similar problems in the spring of 2006.
“A lot of it is dependent on snowfall, how fast it melts and if you get any rainfall on top of that,” Mahabir said.
Laura Kendall, who lives on Riverside Drive, said new buildings around her are flood-proofed, which seemed to make flooding at her property worse. She also said her neighbours received warning phone calls, but she didn’t.
Okotoks’ municipal manager Rick Quail noted that unfortunately, the town doesn’t have a database of phone numbers, but is hoping to create a public awareness system.
Fire Chief Paul Kaiser said they did try to warn people.
“Unfortunately, in your area, you were under water and it came in very quickly,” Kaiser said. “It took everybody by surprise.”
Kendall asked why the water level monitoring station at Three Point Creek wasn’t used as a warning system.
Mahabir said that all officials can tell from data received at the station is how the flood event compares to previous flooding.
“They couldn’t say this area is going to get wet in this amount of time,” Mahabir said.
East Lineham resident Sonny Skow asked why the floodway area can’t be decreased to allow for more development.
“These are the minimum requirements. Other communities take it further,” Pentney said. “The bottom line is why would we expose people to that kind of risk?”
Flood risk mapping at the presentation showed the floodway, which must be one metre in depth or have a velocity of 1 metre per second or a 0.3 metre rise in water elevation. A flood fringe is where the river water is shallower and moves slower than in the floodway. Development in the floodway should be non-obstructive and low value development, while development in the flood fringe requires flood proofing to reduce damages.
“If we’re starting to develop that area (flood fringe), we’re going to see an impact greater than 0.3 metres,” Mahabir said.
Resident Mike Cooper asked if flooding north of the tracks had been avoidable.
Pentney responded that it appeared that the water couldn’t get back to the river and also that highway construction was a factor, with a narrower channel which backed water up.
Erin Gregg, spokesperson for Alberta Environment, said that there were no real surprises in the information presented.
“There’s really nothing that could have been done differently,” Gregg said. “We can’t control what Mother Nature does, but we can try to protect people as much as we can.”
Mahabir noted that the average precipitation for the area is 130 mm for the month of June.
“By June 5, we were already at 110 mm,” Mahabir said.
The first flood event occurred June 6 to 9, bringing the total to 245 mm of precipitation and mainly affecting eight communities. The second flood event affected 14 communities from June 16 and 19 and brought the total to 369 mm. The peak river flows for the second event in June were very close to the 1996 design event of 954 cubic metres per second, making this a 1:100 year flood event.
“More than two dozen municipalities declared states of local emergencies,” Mahabir said.
The third flood event affected mainly Okotoks and High River from June 27 and 29, bringing the total precipitation to 456 mm. By the end of June, the area had seen three times the normal amount of precipitation.
Council is expecting a study from CH2M Hill Engineering in mid-November, which will be followed by another public meeting.