Work on one of several steep creeks that flooded with debris and water during the June 2013 flood is expected to see mitigation work go into the ground in 2018.
Stoneworks Creek is located on the north side of the valley and meets the Trans-Canada Highway at Palliser Trail. It flows out of the drainage of Lady Macdonald mountain and affects land that is owned by the municipality for future employee housing, land owned by Silvertip, also for future employee housing opportunities, the Palliser developments and Cross Z Ranch.
When the mountain creek flooded three years ago, it affected the Palliser lands when the creek jumped its banks and created a new path through the public land area. The result was that flood debris washed out onto Palliser Trail and into the underground parkade of one residential development while flowing under the highway and inundating the low lying area around the hospital.
The year before, a multi-million dollar flood mitigation project had been completed on Stoneworks Creek, but it didn’t hold up to the sheer volume of precipitation that fell in the valley over several days.
“It resulted in almost a total loss of that infrastructure,” said Michael Fark, general manager of municipal infrastructure, who added there is still disaster recovery funding available to construct mitigation.
“Due to the funding available to redo that project, we are bringing it back and we are proposing to build a mitigation structure on that creek.”
Phase one of the project, the design of mitigation for the creek, will begin in 2017 and phase two, construction in 2018, with an an estimated $350,000 and $3.4 million budget.
According to the budget, $100,000 of the design funding would come from grant funds, along with $3.1 million of the mitigation construction cost. The rest of the funding would have to be found or taken from reserves.
Fark said work is being proposed for higher up the creek than last time to potentially address flood mitigation for new development that could go into the area. However, Fark indicated that level of mitigation might be included in the design, but construction of it would not be part of the 2018 work. Instead, as per the project summary, flood mitigation that could protect future development will be developed when it moves forward.
The “modular approach” to mitigation on Stoneworks Creek would prevent having to decommission and reconstruct mitigation once development is actually moving forward in that location.
“We have brought that project forward at this time as there is no development imminent,” he said.
Project construction is hoped to occur at the same time as the debris retention structure in Cougar Creek – a $48 million project currently undergoing a provincial environmental impact assessment review.
According to the capital budget summary, the two projects have “synergy” as the bulk of the excavation work in Stoneworks could be used as part of the fill needed on Cougar Creek.
There is also work planned in 2017 for Stones Canyon Creek – which is located in the Peaks of Grassi area. The $80,000 mitigation project would construct a diversion structure to protect homes in that development from floodwaters.
The project was created because of council approval of a development on Lawrence Grassi Ridge, which requires mitigation as one of its conditions. The assessment done, stated the project summary, shows that there are a number of existing properties, as well as proposed development, that could be affected and as a result “administration recommends a cost share with the developer, prorated based on the value of existing a new development protected.”
