City spreading “Biosolids” (sewage sludge) on local farm field raises concern
LLocal resident Anne Marie LeBrun wants area residents to be aware of a City practice of spreading biosolids on agricultural lands. She first learned of the practice through a notice received from the City of Ottawa advising adjacent landowners of an imminent plan to spread biosolids on a neighbouring farm :
… we plan to land apply municipal biosolids on agricultural land located on Lots 1 & 2 Concession IV North Gower. Biosolids are a fertilizer and soil building material produced from treated wastewater at the Citry of Ottawa’s Robert O. Pickard Environmental Centre.
LeBrun, having done considerable research since receiving the notice explains she has had many sleepless nights. She is aware that biosolids, made from human waste, contain toxins.
The city’s best management practices tell us not to grow vegetables or graze animals on this land for 5 years! It is not without risk. I own horses that graze on the adjacent land and worse, I’m sure our neighbours have children who play on or near this land as well.”
The area is known to flood so her concerns extend to the possible impacts on water as well.
This is one of those issues that evokes a visceral response, particularly for those who live close to application sites or are in the business of farming. For the farmer, who is simply taking advantage of a program promoted by the City, the program is a source of free fertilizer so long as he/she can live with the risks. For the City, the science acknowledges the risks while appearing to support disposal on agricultural land under certain strict conditions. As well, the program offers an inexpensive way to dispose of an environmentally sensitive byproduct in a manner that is marketed as “green” disposal. For neighboring residents there is the ultimate question of whether or not the risks are adequately managed and why should any risk to health or environment be tolerated at all.
LeBrun, as part of her research, wrote the David Suzuki Foundation to ask for their opinion. An abridged version of the response from Kim Vickers of the Foundation reads:
The David Suzuki Foundation does not support the dumping of sewage sludge, treated or otherwise, on farm land. The potential of heavy metal and chemical contamination of crops grown in soils that are “conditioned” with sludge from sewage treatment plants, and the potential for impacts on animal and human health from consuming those crops, raises concerns.
If human waste was the only substance entering the sewage treatment plant, then sewage sludge would largely contain only nutrients and there would be no problem using it to cultivate crops (after disinfection to kill viruses and bacteria of course). Unfortunately, most sewage treatment plants receive industrial toxic wastes along with human waste. As a result, sewage sludge can contain a brew of nutrients laced with PCBs [polychlorinated biphenyls – in low levels]; dioxins and furans (again, generally in low levels); chlorinated pesticides [such as DDT Aldrin, endrin, chlordane, indane, mirex, etc..); polybrominated diphenylethers (PBDE’s – Flame retardant chemicals); hormone mimicking compounds like Phthalates and nonylphenols and their ethoxylates: carcinogenic polycyclic aromatic hydrocarbons [PAHs]; heavy metals ( in particular arsenic, cadmium, copper, lead, mercury, selenium, and zinc); bacteria, viruses, parasitic worms, and fungi; industrial solvents; asbestos; and petroleum products.
All of these chemicals can, and do contaminate the soil and can contaminate the crops grown in those soils. There is also the associated problem of these contaminants running off treated fields and into local water courses when it rains.
For more information you can see the following article: Biosolids or Biohazards
The treatment or dumping of sewage sludge is only an emerging field of science so the “jury is not in” as to whether such use is actually detrimental to human health. It will be some time until we have all the answers. Suffice to say, there is sufficient cause for concern that we do not support the use of this material for application on farm land.
The issue of spreading biosolids on agricultural lands is not a new one in Ottawa. In fact, a few years ago there was a two year moratorium on the practice and an extensive review process. In the end Ottawa opted for agricultural use.
Ottawa is not alone in the practice of spreading biosolids on agricultural land. Municipalities around the globe wrestle with the issue. It is one of those nasty issues where the science isn’t exact and there are few alternatives for disposal other than landfill or incineration. If Ottawa had a viable waste incineration plant another alternative might exist but at the moment that is not the case. As stated on the City website “Land application is currently the most sustainable and cost-effective reuse option for the City of Ottawa’s biosolids.”
In 2017 Ottawa produced 47,456 metric tons of biosolids. The City spread 27,671 metric tons on agricultural land, produced 15,167 metric tons of agricultural soil products and 79 metric tons of commercial liquid fertilizer. 5495 metric tons remained in storage at year end accounting for 100% of all solids produced.
The City of Ottawa supplies, delivers and applies biosolids free of charge to eligible farms and requires that:
- Biosolids must be incorporated into the soil within 2 hours of their application
- Stockpiling of biosolids in fields is not permitted
- Local residents within 450m of the spreading location are notified a few weeks before the biosolids are applied
- Biosolids are not spread on weekends or statutory holidays
The City also offers free well water testing upon request to households adjacent to biosolid application sites. Tests are taken up to four weeks before biosolids are applied, and between 10 and 12 weeks after application. All well test results are provided to the well owner.