Columbia Valley Pioneer Staff

The District of Invermere will spend up to $190,000 and install an enhanced aeration system to mitigate the “offensive odour” arising from its wastewater treatment lagoons.

Council passed the resolution at its August 8 meeting after a report from Director of Public Works and Operations Angela MacLean.

She said that residents and district staff noticed the strong sewage odour this spring, when the source was identified as Lagoon 1 at the Wastewater Treatment Plant. She noted the odour lasted approximately four weeks before the lagoon stabilized.

MacLean said staff discovered that the dissolved oxygen (DO) in Lagoon 1 was very low, causing the good bacteria (that breaks down the waste products) to die off. This condition likely occurred due to a quick change in the weather from winter to spring, in addition to issues with the aeration system. She noted the odour problem demonstrated that the infrastructure was “struggling to provide enough dissolved oxygen to maintain the necessary aerobic conditions for the system to operate properly.”

MacLean said installing a system that can continuously monitor the DO levels will give staff a better understanding of lagoon performance, allowing them to make adjustments in a timely manner. She noted they are investigating ways to retrofit the existing system, adding the preferred proposal is to install a large number of commercial air diffusers. In the end, the new system will be easier to inspect, repair and replace as necessary, MacLean pointed out.

The estimated cost to replace the current aeration system is $160,000, but this project is not included in the 2023 Capital Plan already adopted by council. Therefore, staff recommended that the funds from the prior year surplus in the Sewer Operating Plan be used. This fund had a balance of $1.4 million as of December 31, 2022.

Staff plan to start the project immediately to permit installation this fall.

“If the aeration improvements are not installed prior to this winter, then there is a high likelihood of odour issues occurring in spring 2024,” MacLean said.

Mayor Al Miller told the Pioneer that he believes the retrofit will correct the odour issue. “The explanation from our engineering (department) certainly made sense to me. Our system is aging and needs to be updated as well.”