FAQ Category: Odour

Why is construction causing odours?

As part of this project, we are excavating contaminated soil, as well as peat and other organic material found in the soils. This creates some odour.

What am I actually smelling?

Soil and groundwater in the Port Lands contain varying concentrations of metals, polycyclic aromatic hydrocarbon (PAHs), petroleum hydrocarbons (PHCs) and volatile organic compounds (VOCs). These may be released during excavation. Some of these compounds are detectable as odour. Excavation in areas with the highest contamination and the most odorous soil started in March 2019 and is slated to be completed in fall 2020, after which time the odour caused by construction should be less of a concern.

There are also ongoing industrial processes elsewhere in the Port Lands. These industrial activities outside of our construction site also produce odours. For this reason, our Odour Monitoring Plan includes monitoring odour at locations upwind and downwind of our construction site. If air becomes more odourous as it passes through our site, we know that it is likely caused by our construction activities.

What are PAHs, PHCs, and VOCs, and where did they come from?

Polycyclic aromatic hydrocarbon (PAHs), petroleum hydrocarbons (PHCs) and volatile organic compounds (VOCs) are contaminants in the soil as a result of decades of heavy industrial uses in the Port Lands.

Some examples of materials containing PAHs are coal and old heating oil. They are also commonly used in the manufacturing of asphalt shingles and other bituminous products like road asphalt. The Port Lands was home to a coal storage yard, as well as factories and oil refineries which are a likely source of this contamination.

Some examples of materials containing PHCs are gasoline, diesel, heavy oils, kerosene and other fuels. These PHCs were left by the oil refineries and fuel storage facilities that existed in the Port Lands for much of the 1900s.

Volatile Organic Compounds (VOCs) are compounds released into the air from industrial processes such as burning fuels and plastics manufacturing and products like industrial solvents, chemical degreasers, and consumer products like cigarettes and plastics. The many industrial uses and poor-quality materials used to create the Port Lands are the main contributor to VOCs.

These compounds are not unique to the Port Lands and can be found elsewhere in Toronto’s downtown.

Is it safe?

While odours resulting from our work may not be pleasant, they’re not necessarily linked to air quality or health concerns. Humans can detect the smell of certain compounds at very low concentrations. Naphthalene, for example, is detectable at a very low level – it’s a smell often associated with mothballs. While it’s detectable at low levels, it would take a much higher concentration to negatively impact air quality.

Air quality is being continuously monitored at locations around the perimeter of the site, both upwind and downwind of our work. Additional real-time point source monitoring is being done on-site using a handheld photo-ionization detector (PID). The threshold for this project has been set at a conservative level to be an indicator and is not related to air quality or health concerns. If the measured difference in total Volatile Organic Compounds (VOCs) between upwind and downwind readings exceeds project thresholds, the project team will collect a sample to conduct additional testing to ensure individual VOCs are less than levels set by the Provincial Ambient Air Quality Criteria.

What are you doing to control odour?

Our Odour Management Plan includes a monitoring program to continually assess conditions within and at the boundary of the site.

We have measures in place to mitigate odour as much as possible. This includes changing work practices, stopping work, perimeter odour socks, using odour neutralizing misters and, if necessary, odour suppressing sprays and foams.

When we receive complaints about odour, we react immediately and deploy our air monitoring specialist to the location to assess the situation.

I’m smelling a strong odour, yet your monitoring results shows no or little detection of odour. Why is that?

While we take all measures possible to control odour, the excavation process will inevitably cause some unpleasant odours. For many people, odour is detectable below our trigger thresholds.

How are you measuring odours?

We use a nasal ranger olfactometer to measure existing odour in and around the construction site. Specialized technicians who use the olfactometer are trained to detect both the level and quality of odour.

What if your monitoring shows odour is too high?

We can manage odour in a number of ways, including minimizing our work area, applying odour reducing sprays and foams to materials that may be causing the odour. We are continuously improving our control measures on-site. Frequent and timely input from the local community will help us remedy any issues as quickly as possible.

What if your monitoring shows air quality is negatively impacted?

If air quality exceeds our criteria, we will immediately investigate to determine the potential source, review the controls in place at the construction site and implement mitigation measures. We can also stop, change or slow down work as a mitigation measure. There have been a few readings that show increased levels of certain VOCs during excavation. When this happens, we take corrective actions and have increased our field monitoring at these locations. While these VOCs can also be present in ambient air, we are still reporting to the Ministry of Environment, Conservation and Parks and Toronto Public Health. We continue to implement and adapt our approach to address new and daily site conditions.