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 been treated with primary treatment (filtering and settling of solids), but not with secondary treatment (remaining material being broken down by bacteria or by 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. Although some storm water is flowing into the lake as it should, Innes says some of it is still connected below city streets to the sewer system in unmapped and unknown locations. They are separated by city crews whenever they are found. Innes stated that the goal is to eventually have all stormwater diverted to the lake and away form the sewage treatment plants.
The sewage treatment facility is located near Grohman Narrows on the shores of Kootenay Lake. It releases its effluent into Kootenay River following primary and secondary treatment.
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. Operators of sewage plants have noticed a surprising low flow into the plant. Divers have also discovered leaks in this force main, which has resulted in unknown amounts raw sewage being released into the river. Innes claims that this has happened four times over the past five years.
The province has ruled on several occasions that the city is not in compliance since 2017 because data or test results were not submitted or monitored often enough. These data include 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 effluent releases and insufficient data were documented in six warning letters and noncompliance letters sent to the city by regulators at the Ministry of the Environment and Climate Change Strategy. They were sent between 2018 and 2021. These documents can be searched at https://bit.ly/3x9Y27q.
These compliance problems have not been penalized by 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 do show them everything they ask for. 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 the increase in unusually concentrated effluents from the city over the years. This is Innes’s explanation for the increased number of restaurants and breweries in 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 was being dumped at a separate site from the treatment plant for many decades. The province issued a notice on Sept. 1, 2021 prohibiting disposal. Innes stated that the city has had to hire an outside contractor to take 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 will spend millions on the plant’s renovation or replacement over the next few years. He expects to receive most of the money in grants from senior government officials. 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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