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Wastewater Lagoon Upgrades

Town of Stettler

Project Description

Tagish Engineering Ltd. was commissioned to repair the Cell #6 sewage lagoon in the Town of Stettler. The Town discovered effluent seeping through the clay berms, causing the lagoon to be in contravention of Alberta Environment regulations. The lagoon walls had also been severely eroded and a proper side slope needed to be re-established. After commissioning a lagoon bio solids survey report, desludging 40+ years of accumulated bio solids in Cell #6 began. During the year-long desludging process, it was found that Cell #5 was also experiencing problems with effluent seepage and erosion. As the desludging of Cell #6 was time consuming and expensive, Tagish proposed a design and methodology to reconstruct the clay liner of Cell #5 without desludging the lagoon first.

Despite the primary contractor’s initial skepticism, re-establishment of an impermeable clay liner was completed efficiently according to design. The Cell #5 boundary berms were reconstructed despite the large amount of bio solids present. Desludging of Cell #6 finished soon after, and the Cell #6 boundary berms and clay liner were promptly reconstructed as well. The field inspector and geotechnical consultant were able to properly judge the integrity of the existing clay liner, reduce the scope of clay liner replacement, and reduce the overall amount of clay material required to re-establish an impermeable clay liner, thus completing the project well under budget.


Town of Stettler




  • 22,000 cu.m. of biosolid removal

  • >10,000 cu.m. of import clay for new liner

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