Storm pond with wetland plantings and willow stakes
The Town of Claresholm is a community of approximately 4,000 residents located 125 kilometres south of Calgary. In 2014, the town retained Associated Engineering to conduct a stormwater management study and create a hydrologic / hydraulic model of their existing stormwater system. The main objective of the study was to confirm the system’s current capacity and performance and determine future capacity, based on growth and redevelopment. In addition, the town wished to assess the downstream impact of the drainage system and develop a strategic capital improvement plan to improve service levels.
Three months after the study began, Claresholm experienced a significant storm, with 160 millimetres of rainfall over two days. The storm caused overland flooding and extensive property damage.
Storm pond outlet into downstream Frog Creek drain
In an ironic twist, this unfortunate event provided a unique opportunity to verify the stormwater model in real time.
“We used actual measurements and elevations taken during the flood event to calibrate our storm model.” - Project Manager, Darryl Schalk
The team employed a risk-based approach to develop the stormwater capital improvement plan. The plan identified 23 priority projects and recommended implementing the top ten projects over a five-year Stormwater Improvement Program.
Associated assisted the Town in successfully securing funding for the Phase 1 project under both the Disaster Recovery and the Alberta Community Resilience Programs. Phase 1 included detailed design, tender and construction services of Frog Creek Drain Channel Repairs, a new stormwater management facility, and 8th Street Ditch Upgrades.
The new stormwater management facility has four cells, each with deep and shallow ponds and wetland areas linked hydraulically through control structures. Within each cell, water flows through a curvilinear stream lengthening the time water takes to travel through the facility.
“The facility improves stormwater quality before its release downstream to a creek. More than 140,000 wetland plants, willows, and trees were planted to provide additional filtering and environmental benefits for wildlife.“ - Stormwater Engineer, Adam McDonald
The new facility provides nearly 200,000 cubic metres of active stormwater storage capacity.
The existing ditch along 8th Street West was enlarged to provide greater water flow capacity to reach the storm pond. Approximately four kilometres of ditch were upgraded, including twin 1300 millimeters diameter culverts at multiple road crossings, requiring significant coordination with landowners.
Phase 2 - golf course channel upgrades
As the Phase 1 project neared completion under budget, Associated assisted the Town to secure Alberta Environment’s approval to expedite part of the Phase 2 storm project within Phase 1 funding. The work included stream widening and other improvements to a stormwater channel through the local golf course.
The stormwater improvements have already demonstrated their benefits to community resilience, protecting the town from flooding during the 2018 spring snow melt.