Unexpected lagoon problem to cost $1M, delays other projects

The unexpected but immediately necessary replacement of the decades-old clay liner of one of the town's sewage lagoon liners . . .

The unexpected but immediately necessary replacement of the decades-old clay liner of one of the town’s sewage lagoon liners has put a million-dollar dent in the Stettler’s 2016 budget.

Council heard during the regular meeting on Tuesday, Feb.9 that in late January, staff performing routine inspections of the lagoon discovered cell six was seeping effluent, or waste.

Any breach of a waste management system resulting in effluent leaking into the surrounding environment requires the municipality contact the Alberta Ministry of the Environment, which the town did immediately.

Staff also lowered the water level in the lagoon to reduce pressure on the lagoon cell walls, or berms, halting the seepage. The solution is only temporary, Melissa Robbins, director of operations, said. The town cannot afford to close the cell or have it running at limited capacity for long if the town is going to remain capable of handling the effluent from the community.

Greg Switenky, Stettler’s chief administrative officer (CAO), told council that staff investigated the cause of the seepage and discovered that the cell’s clay liner, installed in the 1960s, was severely degraded and could not be repaired.

The cost of replacing the liner would cost roughly $1 million, and the replacement is an urgent and immediate need.

While the town does have the million dollars needed to replace the liner, the money is spoken for in the 2016 capital budget, Switenky explained.

The project for which the money has been allocated for is the three-year replacement of wastewater and water lines on 51 Avenue from 57 to 61 streets. The project would also include any soil remediation and the repair of the roadway and sidewalks in the construction zone.

Delaying the project, which is scheduled to be completed in two phases, one or two years wouldn’t cause too much damage to the town’s maintenance schedule, Robbins said, but anything further than that was not recommended.

Staff recommended the same type of clay liner be installed in the cell, citing its five decades of use as a sign of the product’s longevity. The clay would be sourced locally as well, benefiting a local landowner.

Environmental impact minimal, staff says

Robbins said the impact of the seepage from the lagoon is expected to be minimal.

Given how slowly the lagoon cell was seeping and how quick staff were to discover the leaking effluent, it’s believed less than 15 cubic metres of effluent escaped into the environment, most of which escaped into a nearby ditch rather than the nearby Red Willow Creek.

The land surrounding the lagoon is predominantly clay as well, though not an impermeable clay surface like an artificially created clay liner, Robbins said.

Though the clay surface would slow any leaks of effluent, cracks and sandy surfaces in the clay surrounding the lagoon means staff cannot guarantee that the surrounding clay would prevent seepage.

The town would be able to replace the liner in sections by walling off the section being replaced, replacing the liner in the section, taking down the temporary walls, and moving to another section.

The work must be completed during the summer months as the effect of cold temperatures on the clay and surrounding soil would negatively impact the installation of the liner.

Given the urgent need to replace the liner, council voted unanimously to delay the Railway Avenue project and divert the money to the lagoon liner replacement.

Robbins is now sourcing the clay for the project as well as completing the technical drawings, with the project anticipated to go to tender in March. If prices come in low enough, Robbins said she would like to replace the liner of cell five, which was built the same year as the seeping six. While five hasn’t shown any sign of leakage, its liner is in a similar condition, she said.

The project, if weather cooperates, would take six to eight weeks to complete.


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