One of the most significant responsibilities for Edmonton International Airport (EIA) is the treatment of spent glycol from aircraft deicing. Some of the deicing fluid is recovered from the deicing pads; however, accumulated snow and deicing fluid is also directed toward the main Stormwater Collection and Containment System (SCCS).
From 2000 through 2011, EIA successfully used a natural wetland system to treat glycol contaminated stormwater. With growth in aircraft operations the treatment capacity of the system was challenged. In 2011, EIA upgraded the system to an engineered treatment facility (Subsurface Aerated Biofilter Treatment Facility or SABTF), that increased treatment capacity, decreased time to treat, and provided the opportunity for future expansion with a much smaller environmental footprint than the original system.
Growth at EIA has increased deicing fluid use from just over 500,000 liters of deicing fluid in 2006 to between 2.5 and 3.5 million litres from 2014 to 2019. This increase in use drove the need for EIA to increase stormwater containment capacity in the SCCS and treatment capacity in the SABTF.
What is that scent?
The holding ponds and ditches that are part of the SCCS can generate a chemical scent caused by the natural breakdown of glycol in the spent deicing fluid to ethanol (common alcohol) and acetic acid (vinegar). The scent can be more prominent when combined with the breakdown of organic matter from vegetation in the ditches and holding ponds. Overall this storage and treatment process is better for the environment as compared to other treatment methods.
Why am I noticing the scent now?
Once snow starts to melt in the spring, we segregate the more contaminated stormwater from the main collection ditch into the South Retention Pond (SRP), which feeds the SABTF for treatment. If required, the North Retention Pond (NRP) can be filled as well. Since the SABTF will not operate efficiently until warmer night time temperatures are reached in mid-May, the pond(s) sit and various chemical reactions start to naturally occur. Some of those reactions create odours that are not harmful but can be unpleasant.
Is it harmful? What should I do?
EIA completed an air quality study that confirmed the scent presents no health risk and contains compounds at concentrations well below provincial air quality criteria. However, if you are uncertain whether the scent may come from another source, such as a natural gas leak, please contact your natural gas provider immediately.
How can I tell if the scent is a gas leak or some other problem?
Scent in the holding ponds is caused by the breakdown of deicing fluid which contains ethanol (common alcohol) and acetic acid (vinegar), similar to the scent of many disinfectants or common cleaning products. When the glycol breaks down in the presence of organic matter, the scent can range from sweet (glycol) to pickled garlic (glycol and organic matter breaking down simultaneously).
In contrast, natural gas is deliberately scented with mercaptan, a sulphur-based additive that smells similar to rotten eggs. Customers of AltaGas Utilities can obtain a “scratch and sniff” card to aid in identification of the smell of the mercaptan. To obtain a card, contact the AltaGas Utilities Contact Centre 1-866-222-2068. Again, if you are uncertain, you should immediately seek professional advice from your gas utilities company.
Safety is always the top priority:
If you smell natural gas outside, call your local utility’s Emergency Line and keep people and ignition sources away from the area.
If you smell natural gas inside a building, leave immediately and call your local utility’s Emergency Line.
AltaGas Utilities Emergency Line: 1-866-222-2068
ATCO Gas Emergency Line: 780-420-5585
What is EIA doing about this?
EIA completed an air quality study that confirmed the scent presents no health risk and contains compounds at concentrations well below provincial air quality criteria.
Since 2015 EIA has invested $10 million to expand and improve both the SCCS and SABTF systems so that as soon as weather permits the treatment process may begin and potentially be completed in a shorter time period. The upgraded and new system components have been in use since March 2016.
EIA continues to work diligently to identify and implement new technologies to control and minimize scent release, both now and into the future. EIA is operating an odour control system trial that will utilize large blower fans and an odour neutralizing agent. At a minimum this should reduce the intensity of the scent and the distance it would normally travel but the system might have the ability to neutralize the odour at the source.
How does the SABTF work?
EIA’s SABTF is an advanced environmental technology that uses bio-filtration to remove contaminants from runoff before it is returned to our community’s ecosystems, namely a tributary of Whitemud Creek.
Water collected by the SCCS is fed into the SABTF, which uses a combination of aeration and assisted biological activity to remove impurities and contaminants. The SABTF is weather dependent and cannot be operated until nighttime temperatures are warm enough to sustain the continual movement of water within the system. The recent expansion provided additional treatment capacity at the SABTF, so collected water may be treated in a shorter time period aiding in elimination the scent earlier in the treatment season.
For more information please visit our Stormwater Collection and Containment System and Subsurface Aerated Biofilter Treatment Facility fact sheet.