Will sewage treatment in Victoria benefit the environment?
By Katherine Palmer Gordon, June 2014
With a likely capital cost of between $800 million and $1 billion, it had better. Focus explores the issue with two scientists.
Last December, retired University of Victoria ocean physics professor Chris Garrett wrote to Focus, along with some of his former marine science colleagues, stating: “The allegedly scientific arguments put forward in support [of land-based secondary sewage treatment] are very superficial… [there is no] detailed, quantitative, rational analysis of what the problems are with the present system or how the proposed schemes will fix them.”
Garrett is an expert in ocean dynamics and his CV includes extensive analysis of the environmental impacts of waste disposal in marine environments. Although retired, he remains keenly interested in oceanographic issues like this one where, as he puts it, science meets society. He’s also reviewed what he describes as excellent studies of the sewage issue undertaken by CRD scientists. He says no-one has conclusively established that there are problems with the CRD’s current preliminary sewage treatment system: “Fundamental questions still remain unanswered,” he says.
On that premise, of course, it’s also true that no-one has proven that there aren’t problems with the current system. But with the public debate over sewage treatment mired in political rhetoric and Seaterra spin, confusion reigns supreme. The average citizen can be forgiven for finding it difficult to discern fact from fiction.
Garrett is sympathetic. While he believes concerns over the current treatment system are overstated, he’s also tried to be as objective as possible in what has become an intensely polarized discussion. “I object to people on any side of this issue making absolute statements that Victoria’s current sewage output is toxic or that it’s harmless,” he says, “or that secondary treatment is the only solution or that the current system is perfectly fine. Before we can decide that, we need to make sure we’ve correctly identified and quantified the problems so we can know with certainty what is worthwhile and effective.”
The status quo vs. secondary treatment
Currently, Victoria’s effluent receives preliminary treatment only. Screens collect about ten percent of the solids coming through the pipes, or about 657,000 kilograms annually, which are taken to the Hartland Landfill for disposal. The remaining 90 percent—nearly 6.7 million kilograms annually—is discharged into Juan de Fuca Strait, in what Garrett describes as a “thin, grey soup,” from two outfalls at Clover and Macaulay Points, more than a kilometre from land and at a depth of about 60 metres.
The CRD confirms that it routinely measures “upwards of 200” organic and inorganic contaminants in that “soup.” But those who favour this preliminary treatment system argue that the total volume of effluent coming out of the pipes comprises more than 99 percent water, and that its contents are effectively diluted, dispersed and degraded by the active tidal currents in Juan de Fuca Strait. Contamination in the immediate vicinity of the two outfalls is also believed to be relatively minor.
Critics, however, cite a litany of environmental concerns. Sediment samples taken at the outfalls have failed provincial contamination standards. Organic material and dissolved nutrients in the effluent consume oxygen in a process called eutrophication, said to endanger marine life. Moreover, toxic contaminants in the liquid waste are being absorbed by the marine food chain. Human pathogens and fecal coliforms near the outfalls also pose a hazard to humans. This all adds up, say the critics, to the need to put something more than preliminary treatment in place.
In 2012, new mandatory minimum effluent quality standards were enacted by the federal government. Environment Canada requires at least secondary treatment as the way to achieve those standards. Secondary treatment removes biodegradable material from effluent before it is discharged, but it doesn’t remove all the contaminants, so those it misses get flushed out to sea. Material remaining after secondary treatment, called sludge, contains all the contaminants that secondary treatment did remove, which means the sludge must be disposed of safely. Options for disposal include landfill, incineration, gasification, conversion into energy, or use as fertilizer, all of which pose issues of their own.
Chris Garrett’s take
Garrett says that eutrophication, or oxygen depletion, can indeed be a problem associated with dumping minimally treated sewage effluent into confined waters. However, he states, “The strong tidal currents off Victoria recharge the local waters with oxygen constantly. The addition of a relatively small amount of extra nutrient material isn’t likely to make any difference.”
He adds: “In fact there is a lot of thriving marine life present in the sediments near the outfalls, which suggests that oxygen depletion isn’t having a significant impact.” That’s not to say that the dilution effect of active ocean waters is foolproof. “Discharges might not be a problem now, but the cumulative impacts after many years might be a problem in future.”
Occasionally, plumes of sewage containing fecal coliforms also reach the surface near the outfalls. Most of the time the coliform count falls below provincial guidelines for recreational waters, so the plumes don’t pose a safety issue. That’s not always the case, however. Garrett notes: “The guidelines are occasionally exceeded.”
That’s a problem for humans rather than fish, as is the presence of bacteria and viruses in surface water. “Bacteria tend to die within hours, but viruses can persist for many days,” says Garrett. He says this is a good example of an issue that requires more research: “There are anecdotal claims of infections from exposure to the sea in the vicinity of the outfalls, but no epidemiological evidence.”
Serious concerns have also been raised about heavy metals, pharmaceuticals, industrial waste, micro plastics, and chemicals contained in the effluent, and the negative impact not only on the areas surrounding the outfalls, but on marine life in the Strait itself. High levels of PCBs have been found in marine mammals, and flame retardants and similar pollutants are also worrying.
“PCBs are a real problem,” says Garrett, “that is a known fact. That’s why they were banned back in the 1970s. But they’re very persistent and they get recycled again and again into the environment, so are taking a long time to disappear.” He points out, however, that in local waters, most of the PCBs aren’t getting into the marine environment from the sewage system. “They’re entering the marine environment from the atmosphere, river run-off, and sediments contaminated by former industrial activity.”
Emerging problems these days arise from other persistent pollutants such as flame retardants, which unquestionably are entering the ocean via the sewage outfalls: “Controls are only now being imposed on use and disposal of flame retardants, so levels will have to be monitored. This is another example of a very important issue we need to understand better. Simply treating for removal of these pollutants from the effluent may not be good enough, for the same reasons as PCBs and metals. Limitation of use in the first place may be the only effective control.”
“The other thing to remember,” adds Garrett, “is that secondary treatment doesn’t destroy many contaminants. Some are still discharged into the sea, and others simply get concentrated in the leftover sludge instead of the liquid effluent. Whether that’s worse for the environment or not depends on what you do with the sludge. If you dispose of it on land, it may contaminate surface and groundwater. If you incinerate it, it may produce dioxins. What’s the environmental impact compared to the contaminants being absorbed and buried in the sediments around the outfalls? We don’t know, because an objective comparison hasn’t been done.”
Under the CRD’s plan, no final decision has been made on what to do with the sludge, though use as a fertilizer has been rejected.
Given that secondary treatment doesn’t remove some of the contaminants, tertiary or “advanced” treatment has been raised as a better solution to the federal government’s mandated treatment of CRD wastewater. Advanced treatment can remove additional contaminants from wastewater after it has been through the secondary process, including some heavy metals and nutrients like phosphorus and nitrogen. Pathogens and other microorganisms may be removed through a final disinfection stage, often called “polishing.” The goal is to produce effluent suitable for safe discharge into the environment or for reuse in certain applications. In parts of the world where water is scarce—Namibia, for example—the resulting water is used for human consumption.
Water may be plentiful in the CRD, but Victoria’s Sewage Treatment Action Group (which has developed “the RITE Plan”) believes advanced treatment is the way to go. Green Party MLA Dr Andrew Weaver has publicly supported the concept. Colwood has jumped on board, opting out of secondary treatment in favour of its own advanced treatment plan with resource recovery and recycling of wastewater for irrigation and similar purposes built into the concept.
Garrett doesn’t profess to be able to speak authoritatively on the merits of advanced treatment, but is emphatic that his questions remain the same: “We need to analyze the facts before we jump to solutions that are expensive, address problems that might not exist, and create other potentially worse environmental impacts.”
Dr Don Mavinic, however, is more than qualified to weigh in on where advanced treatment fits into the discussion. A professor in the Department of Civil Engineering at the University of British Columbia, Mavinic’s research over the last four decades of his career has included biological waste treatment processes, wastewater residuals treatment, phosphorus removal and recovery, and disinfection by-products in drinking water; and his department at UBC is engaged in extensive research into various aspects of advanced treatment.
Mavinic agrees with Garrett about the need for hard facts. “There are basically several questions that have to be asked before deciding on advanced treatment,” says Mavinic. “What’s left in the water that you really need to deal with? How much of it is there? What’s the potential environmental impact—where is the water going? Into saltwater, like Victoria, or freshwater or into another particularly sensitive environment? Do you intend to recycle it?” To make sense of the issue, he says, “You have to do your homework first.” In the meantime, he adds, there’s still uncertainty in scientific and engineering circles about some aspects of advanced treatment.
There are also bad ways to do advanced treatment as well as good ones. But right here in BC, points out Mavinic, is a model of how to do it in the best possible way that current technology can offer. It’s a model that most of Western Canada has followed—and that the CRD should, at minimum, have a long, hard look at before it finalizes its secondary treatment plans.
The nutrient issue
Mavinic says that the typical issue of concern that leads to adopting an advanced treatment system is the presence of excess nitrogen and phosphorus in effluent, both of which nutrients are excreted in human waste and have potentially negative environmental impacts in water, including eutrophication and algal blooms.
One way to remove these nutrients is by the use of chemicals such as alum (potassium aluminum sulfate) or iron salts (such as ferrous sulfate). But there’s a problem that goes hand in hand with that process: the nutrients end up in the leftover sludge, along with the chemicals and any metals that might have been picked up in the process—and that sludge can’t be burned, used as fertilizer, or recycled in any other useful way. (The CRD admits that such chemicals “will be used during chemically enhanced primary treatment for wet weather events.”)
“This is a huge problem in Ontario right now,” observes Mavinic, who is currently advising the Ontario government on this issue. “It’s become very contentious. Very few landfills will accept the sludge now. Most incinerators won’t touch it. Ontario has ended up with this chemical soup that has to be stored somewhere because you can’t do anything with it.” For now, the sludge is simply contained in holding ponds.
Some heavy metals, such as nickel, can only be extracted using a chemical process. But for nutrients like nitrogen and phosphorus there is a smarter approach, and Mavinic says BC’s Okanagan Valley has led the way. “Biological nutrient removal technology is a process that was first pioneered in South Africa and adapted for use in a cold climate setting right here at UBC. Kelowna was the first place to use the treatment process 30 years ago. It’s now used throughout the Okanagan Valley and much of BC, as well as Alberta and Saskatchewan.”
The Kelowna model eschews the use of chemicals to treat nutrients in favour of a biological process that results in the nitrogen being converted into gas and the phosphorus being absorbed into reusable biomass. “You still have leftover sludge,” points out Mavinic, “but because it doesn’t have any chemicals in it you can now gasify it safely and the water can be discharged into Okanagan Lake.”
At the same time, the lake is the source of drinking water for 100,000 people in the Okanagan Valley.
Is this a model the CRD should be interested in? “Victoria is different from the Okanagan, where they’re discharging their effluent into a lake system,” says Mavinic. The ocean off southern Vancouver Island, he says, is a “giant sink” that isn’t as sensitive to some of these contaminants. “Ocean water is also typically phosphorus-deficient,” he says, “so the level of sensitivity just isn’t the same as in Okanagan Lake, say.”
But, Mavinic continues: “It depends very much on what is coming out of the pipes. You have to understand that before you can be definite that there isn’t a problem that needs treatment of some kind.”
Kelowna’s treatment, called Bardenpho Biological Nutrient Removal, requires large tanks and would occupy a much bigger footprint than is available at the McLoughlan Point site. Kelowna’s plant, which will serve a population of about 161,000 people by 2030, is located on a 9-hectare property. The McLoughlin Point site, which CRD projections have shown could need to serve an equivalent population up to 493,000 by 2030, is only 1.4 hectares.
Cleaning up the trace contaminants
Another key issue is how to deal with additional trace contaminants remaining in effluent even after such advanced treatment: contaminants such as pharmaceuticals, caffeine and endocrine disrupters, the latter found in many household and industrial products. These chemicals can interfere with hormone systems in mammals, leading to cancer, birth defects and other developmental disorders.
In May, the CRD confidently announced it plans to add an “advanced oxidation” process to the secondary treatment plan, stating that this process will “significantly reduce the level” of these types of contaminants in the region’s discharged effluent.
“Advanced oxidation can certainly help,” confirms Mavinic. “It’s a lot better than doing nothing. Ozone, for example, is a powerful oxidant in increasing use for disinfecting water rather than using chlorine, and it may be useful in dealing with some trace contaminants as well.”
But Mavinic also says there are no guarantees as to just how effective the process is in practice. “The fact is that there really isn’t any effective technology out there in the marketplace yet to deal with these other contaminants. It’s coming, but it isn’t there. This is a very young science still. There’s a huge amount of research going on globally right now on this subject, including here at UBC, but the jury is still out.”
He includes in this judgement the Membrane Bioreactor (MBR) technology used at Dockside Green: “Frankly, the jury is still out on the efficacy of MBR. It was developed for the drinking water industry, not wastewater treatment. The industry is now looking at wastewater treatment applications and we’re working on a pilot plant here at UBC to test its efficacy and see if there are any real differences in output to the Kelowna model in terms of processing nutrients. That’s a long term process, and the jury is still out yet as to whether it will be effective in treating micro contaminants, pharmaceuticals and other trace contaminants, let alone nutrients. No-one has the answer yet. We’re a long way away from making any recommendations on it.”
Microplastics, found in both personal care products and fleece clothing—and released into wastewater—have also lately become a contaminant of concern. Scientists studying the issue agree that microplastics may pose problems in the marine environment because of their increasing abundance, their longevity, and their demonstrated ingestion by marine organisms. Mavinic says, “I haven’t seen any published literature or even heard of anyone doing any meaningful research on effective treatment for microplastics. I don’t think anyone has any idea what will deal effectively with that. If anyone is making a claim that there is a system to treat them effectively, I would love to see their data. It would have to be very convincing. Let’s just say it would be a real stretch to make a claim like that.”
Mavinic says unanswered questions include exactly what “trace contaminants” need to be targeted: “There are so many different types of chemicals out there and they all respond differently to various treatments.” Exactly what impact those contaminants are having in different environments also needs to be considered. “There are still many, many unknowns,” concludes Mavinic bluntly.
Where to from here, then?
On this point Mavinic is completely unequivocal: If the CRD is committed to secondary treatment, planning ahead to integrate effective advanced treatment such as biological nutrient removal into the process is simply prudent, both from cost and environmental perspectives.
“Ontario is facing that question right now as it looks to upgrade its secondary treatment facilities,” he says. “Will it move to advanced biological treatment to deal with the nutrients going into the Great Lakes? The answer is probably ‘Yes’. The lakes do have problems with excess nutrients and no-one wants any more chemical sludge to deal with. It’s a much more sustainable environmental approach and that’s why the Okanagan adopted it decades ago.”
Chris Garrett simply favours doing the math first. He likes to adapt a borrowed quote: “I’m not necessarily anti-sewage treatment, I’m pro-arithmetic,” he concludes.
Identifying the problems and doing a thorough quantitative analysis of all of the factors is about good decision-making, he says, whatever treatment solution the results favour in the end. “Without that, people are simply going to stay confused about what the right thing is to do.”
Katherine Palmer Gordon is the author of six books of non-fiction, including several BC bestsellers and a Haig-Brown prize-winner.