Wastewater treatment plants: the whole picture

Engineers have a responsibility to address projects in their entirety, not just the infrastructure.

Ever think about what happens inside the pipes after flushing the toilet?

Worldwide, about 330 km³ of wastewater is produced per year. Wastewater is generally defined as any water that has been affected by human use.

According to an OECD report published last year, urban wastewater is the leading source of pollution in Canadian water bodies. The wastewater produced in Canada in 2015 was enough to fill 82,255 Olympic swimming pools. Of this, 82.4 billion litres is from BC.

For decades, the British Columbia city of Victoria dumped raw sewage into the surrounding waters. The rationalization for this practice is that ocean currents wash away the sewage naturally, and therefore wastewater treatment is not necessary. However not everyone agreed with this sentiment. Local divers claimed that this method was toxic to underwater ecosystems, as indicated by dead zones and other irregularities that have developed on the ocean floor.

Many citizens were strongly opposed to the dumping, to the extent that, in 2004, a local elementary school teacher created a group — known as the People Opposed to Outfall Pollution, or POOP. Their mascot, a smiling life-sized piece of feces, promoted the campaign against the disposal of untreated waste into international waters. He retired once plans for a wastewater treatment plant were launched.

Washington State, which is just across from Victoria, is directly affected by the sewage dumping into the Strait of Juan de Fuca. Just last year, the neighbouring state proposed a travel restriction on Victoria in an attempt to expedite the building of the plant.

Just last year, the construction of a wastewater treatment plant commenced in Esquimalt, a township about 5km West of Victoria. This was not an obvious solution — there was a lot of debate around this topic between government officials and locals.

Like most engineering projects, there are many angles to consider when designing and installing wastewater treatment plants. The most prominent issues surround the social, economic, and environmental impacts of wastewater treatment systems.

One cause for opposition is obvious — living near a wastewater treatment plant can be very smelly.

Residents are reluctant to live with the stench, therefore building a treatment plant could lead to a reduction of the surrounding community’s property values.

This issue could be avoided by adding common chemicals to wastewater before treatment. One research team at UBC Okanagan’s School of Engineering discovered that the addition of metal salts, such as table salt or limestone, can reduce the production of odorous gases by 93%.

A 2013 Capital Regional District (CRD) report states that a wastewater treatment plant could initially emit 16,000 tonnes of greenhouse gases during construction, and an additional 8,000 tonnes annually. Many critics, however, believe that the treatment plant was not encouraged on environmental grounds, rather it was politically motivated. They argue that it would be more financially straining than environmentally beneficial.

According a 2015 estimate, the treatment plant could cost up to $1.3 billion. This could lead to an increase in property taxes, and a lower budget for other municipal projects. The CRD suspects that the construction of a plant will also disrupt the tourism industry. The plant will likely damage the view of the harbour, a spot that would otherwise draw tourists.

Engineers have a responsibility to address projects in their entirety, not just the infrastructure. In the engineering field, nothing exists in a vacuum. New projects should be designed to accommodate the social, economic, and environmental sectors, in order to reduce the negative affects.

The development of a wastewater treatment plant may solve preliminary issues of wastewater management, but many argue that the disadvantages in the surrounding systems outweigh the benefits.

Despite the controversy, the plant is on schedule to finish by the 2020 target date.

Research for this article was conducted by Rahma Shakir, in collaboration with Dr. Usman Khan.