Prerequisite work, to determine berm alignment and clearing vegetation in these areas, continues throughout the Drumheller Valley as engineers begin preliminary designs.
Deighen Blakely, senior water resources engineer with Kerr Wood Leidal Associates Ltd. is one of the main consultants involved in this step of the design phase and is very familiar with Drumheller and the Red Deer River.
“We’re very fortunate in Drumheller as the province of Alberta did a flood inundation study,” Blakely told the Mail.
Previously, Blakely was operations manager for Alberta Environment and was directly involved in management of existing flood mitigation systems throughout the valley.
Blakely is also well-versed with flood mitigation, having been involved in writing the flood response manual for the City of Calgary.
She notes the first step designing berms is to determine the preliminary alignments, and Blakely adds some of these alignments have been completed due to the number of berms already in place along the Red Deer River.
Borehole drilling, which is being carried out throughout the Drumheller Valley, is part of this next step. While the drilling will help with potential new berm alignments, it will also help with existing systems. The information gathered from existing structures will help determine whether there are any “pockets of unsuitable material,” and identify ground conditions so engineers can calculate slope and height accordingly.
As berms need to be on the river side of buildings within flood areas, Blakely notes riparian vegetation may be impacted.
“Bio-engineering, combining trees, shrubs, and plants together, definitely is happening in this project. The issue is where trees are located in the dike area itself,” Blakely said. She explains roots can cause voids in the dikes, which can cause further damage to the structure and impact flood mitigation.
“For all these reasons, we avoid larger vegetation on or close to the dike,” she says.
While this may be a concern for Drumheller residents, each tree slated for removal will be replaced with five new trees or large vegetation to maintain carbon sequestration along the river-though this new vegetation will be replanted throughout the community and not necessarily in the same area of removal.
Blakely notes engineering firms are wrapping up the conceptual first phase, and the next step is a preliminary design phase which will identify “stormwater outfalls and utilities” as well as finalizing slope and determining setbacks from both buildings and the river.
Landowners directly impacted by berm alignments will be contacted individually by land agents as designs advance. The Flood Mitigation Office asks for patience as they reach out to these individuals to discuss privately how each landowner will be impacted.
