Between 2017 and 2020, Nelson’s sewage treatment plant, on 15 separate occasions, accidentally released a combined total of more than 3,000 cubic metres of partially treated sewage into the Kootenay River, according to provincial government documents.
The sewage had undergone primary treatment (filtering out solids and settling them out), but not the usual secondary treatment (remaining materials being broken down by bacteria and ultraviolet light).
These incidents occurred during severe rainfallstorms. Many of Nelson’s storm sewers drain directly into the sewage plant, and in rainstorms the storm flow overwhelms the plant, bypassing and flowing around the sewage treatment process.
The city’s public works director Colin Innes says having storm water and sewage in the same pipe was considered acceptable when Nelson’s infrastructure was built in the 1960s. He said that while some storm water flows into the lake directly, as it should be, some is still connected to the sewer system beneath the city streets in unmapped locations. The storm water is separated by city crews when they are discovered. Innes states that the goal over time will be to divert all storm water directly to the lake, away from the sewage treatment facility.
The sewage treatment plant is located at the Kootenay Lake shore near Grohman Narrows. After primary and second treatment, the effluent is released into the Kootenay River.
The effluent looks clear, Innes says, but he wouldn’t drink it. To be drinkable it would have to undergo tertiary treatment – treatment by more advanced bacterial processes, which the plant is not capable of.
Leakages in the force main, a large sewer pipe that runs along the lake’s floor from the airport to the sewage treatment plant, have also led to sewage spillages into the lake. Divers have found leaks in the force major that have led to unknown amounts of raw wastewater being released into rivers. Innes claims that this has happened four times over the past five years.
The province ruled that several times since 2017 the city was not complying with regulations as a result of data or test findings that were not submitted or monitored often enough. These data included data related to fecal carbon, total suspended solids (TSS), biological oxygen demand, turbidity, ultraviolet light transmittance, and turbidity.
On 203 occasions between 2017 and 2020, the amount of material flowing through the system has exceeded the plant’s legal volume limit, although those excesses did not release untreated sewage into the river.
These various releases of effluent and incompletions are documented in six warning letters and letters of non-compliance to the city, dated between 2018 and 2020 by regulators at the Ministry of the Environment and Climate Change Strategy. These documents are searchable at https://bit.ly/3x9Y27q.
These compliance issues have never been punished in the city.
Innes claims that none of the warning letters are random and that his staff is in constant dialogue with regulators.
“We get the inspectors coming through, and we do have really good talks with them. We show them everything they need to see. If you just read these letters on the surface, it would seem like maybe we’re in a tenuous relationship. I don’t believe that to be the case.”
Innes says the plant is not designed for some of the things the city’s provincial sewage permit requires, which causes some technical problems with compliance.
Another problem is an increase in the amount of unusually concentrated effluent coming to the plant from the City over the past few year. Innes states that this is due to the increased number and quality of breweries and restaurants within the city. Some regulatory issues arise because the plant takes longer to break down this organic material.
“Any place that does food prep is a source of a high-strength effluent,” Innes says, “just because there’s so much nutrients that that winds up in the water. And so any organic loading of any kind is going to present a challenge.”
An additional issue is FOG materials – fat, oil, and grit – that build up and clog pumps and pipes and has to be vacuumed out and disposed of. This material has been dumped at the city’s treatment plant for many years. On Sept. 1, 2021, the province sent Innes a letter prohibiting the disposal. Innes said that the city has had to hire an outside contractor to transport the FOG material from the treatment plant to the landfill.
Nelson’s sewage plant and infrastructure was constructed in 1968, with some upgrades since.
“We’ve got an older plant that’s worked for a long time here and really done a lot of heavy lifting for the city,” Innes says. “We’re pretty much at the outside edge of what it’s able to handle.”
Nelson expects to receive grants from senior governments in the coming years, and will spend millions of dollars on the plant’s replacement or upgrade over the next few decades. The consultant Urban Systems is already working on research and monitoring for the project, developing a master plan for the city’s sewage.
Innes states that climate change makes it more urgent to improve the system.
“This is something we really need to tackle,” Innes says. “We need a plant that’s going to be able to handle … projected impacts of climate change. From what I understand, we’re going to be seeing more intense rainfall events.”
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