Stormwater Outfall F7 Erosion Protection and Drains

Fish Creek, Calgary, AB, Canada

Klohn Crippen Berger (KCB) was retained by The City of Calgary to carry out improvements on the Stormwater Outfall F7. The Outfall F7 system conveys stormwater from the Evergreen, Everstone and Millrise areas into Fish Creek. The downstream portion of the system consists of twin 1650 mm-diameter precast concrete pipes, located on the steep 30 m-high valley slope, which discharges into an outfall structure. The Fish Creek valley slope has experienced movements and sloughing prior and subsequent to the installation of Outfall F7. These slope movements have resulted in separation and cracking of the pipes. Extensive toe erosion and further sloughing of the slope occurred during the 2005 flood. As a result, repairs were implemented to prevent further toe erosion, enhance the stability of the slope, and monitor its performance.

The project consisted of approximately 60 m of riprap revetment, the use of grouted steel collars for the pipe repair and the installation of 5 horizontal drains. KCB was also responsible for the habitat compensation plan which included the use of woody plantings, fish habitat boulders and the filling of the riprap voids with pitrun gravel to encourage a natural plant succession into the riprap. Large wooded debris was also implemented into the works.

Ongoing monitoring of the slope is being carried out, and long term rehabilitation options are being evaluated by KCB.


  • Undertake detailed designs
  • Obtain regulatory approvals
  • Prepare tender documents
  • Provide inspection and contract administration services during construction
Stormwater Outfall F7 Erosion Protection and Drains 4 years ago
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