EIA Engineered Wetlands

#Frequently Asked Questions

EIA's traffic grew over the past ten years, and glycol usage volumes increased significantly over the past five years.  Since 2000, a constructed wetland system has been successfully used but its capacity was inadequate to handle additional flows of glycol-contaminated runoff associated with the airport expansion and increased airplane de-icing operations.  The low treatment rate constructed wetlands was upgraded to a relatively high rate engineered wetlands.  With only a $2.5 million construction budget, two of the six trains were upgraded in 2011.  The upgrade was conducted within the existing footprint.  Existing materials on site were reused thereby reducing sourcing and trucking of new materials on site.  The system has been designed and constructed to withstand a cold climate where snow is on the ground for six months of the year and storm water only flows from April to November.  Proper aeration tubing specification was necessary to assure the reliable operation and performance of the oxygen transfer system.  This system has been utilized in other applications such as submerged attached growth reactors, which is an emerging technology.

Biological commissioning occurred in the spring of 2012.  The new system treated the glycol contaminated storm water pond within a 60 day period while consistently producing effluent that is reliable treatment system which is simple to operate and readily expandable.  The successes of this first Canadian application of Engineered Wetlands technology could assist other airports, both Canadian and International, in adopting this approach for handling glycol-contaminated storm water.  The technology could also have application to other types of facilities requiring treatment of high strength, soluble organic contaminants.

Frequently Asked Questions

What is that scent?

Aircraft deicing fluid is primarily ethylene glycol and water. Ethylene glycol readily breaks down in the environment, creating a variety of different chemicals, including ethanol (common alcohol) and acetic acid (vinegar).  Some of those chemicals are volatile at warm temperatures, which allows them to evaporate into the air. The scent is influenced by the release of alcohol and vinegar, and therefore may be similar to the scent of common disinfectants or antiseptics.  It is not harmful to people or to the environment.

Why am I noticing the scent now?

As the snow melts, the run-off washes more of the winter’s de-icing fluid into the holding ponds.   With warmer temperatures, the added heat speeds up the natural breakdown (degrading) of the de-icing fluid.  There has been less snow this winter, and so it is more concentrated. In spring, there is more de-icing fluid in the ponds, and the breakdown of the fluids is occurring faster, so the scent is more noticeable. 

Why is the scent so prevalent this year?

Two years ago, Alberta Environment changed the permit for our engineered wetlands treatment system, to enhance the quality of the water released by EIA into Whitemud Creek. To meet the new criteria, EIA engaged in a major infrastructure project to improve and enhance our treatment system. During the project, we’ve had to operate the system differently while under construction, which has had an unfortunate side effect of enhancing the potential for generating odors in the spring.

Is it harmful?  What should I do? 

The scent from EIA’s engineered wetlands system presents no health risks.   EIA has completed an air quality study and confirmed that the chemicals that create the scent are at levels well below air quality standards set by Alberta Environment.   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.  

Safety is always the top priority:

If you smell gas outside, call your local utility’s Emergency Line, and keep people and ignition sources away from the area.
If you smell 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

How can I tell if the scent is a gas leak or some other problem?

The scent from the engineered wetlands system comes from the release of alcohol and vinegar, and is similar to the scent of many disinfectants, or basic cleaning products. Natural gas (which is odorless) is deliberately scented with mercaptan, a distinctive sulfur-based product that smells like rotten eggs.  Customers of AltaGas Utilities can obtain a “scratch and sniff” card to help learn to identify the scent of the mercaptan in natural gas. To obtain a card, contact the AltaGas Utilities Contact Centre 1-866-222-2067.  If you are uncertain, you should immediately seek professional advice from your gas utilities company. 

What is EIA doing about this?

EIA has completed an air quality study and confirmed that the chemicals that create the scent are at levels well below air quality standards set by Alberta Environment.  

EIA is investing $10 million to improve the system by expanding it so that once weather permits, the treatment process will be completed much faster. New system components are expected to be in place by May 1 (depending on weather). 

In 2017, we will also return to normal seasonal operations for the system, which helps manage the scent generated from the system.

Work is also underway to identify short term approaches to minimize the scent release this year, and to implement new technologies and options to control and minimize scent release in future years.

How does the wetland system work?

EIA’s engineered wetlands are an advanced environmental technology that uses natural processes to remove impurities from water before it is returned to our community’s ecosystems (Whitemud Creek).  The process includes collecting storm water into holding ponds (where chemicals begin to break down naturally), and then releasing the water into engineered wetlands, which filter out remaining impurities before releasing the water into the creek. 

Natural wetlands include wet areas such as marshes, swamps, muskegs and bogs – land-based areas that are soaked with water for at least part of the year. These areas naturally store, filter and clean water as it transitions from land through wetlands, and into creeks, rivers and other water bodies.   Engineered wetlands are a kind of artificial wetland – a man-made area constructed to use the natural processes of a wetland to clean and filter water. 

EIA’s engineered wetlands treatment system is a two-step process that includes temporary storage in holding ponds, followed by a bio-filtration process that mimics the action of natural wetlands.  In this process, water drains from our airfield, carrying de-icing fluid and other impurities into holding ponds. In the holding ponds, the de-icing fluid begins to naturally break down into other chemicals, including ethanol (common alcohol) and acetic acid (vinegar). The scent may be similar to that of a disinfectant or antiseptic product.  

The second step in the treatment process is to feed the holding ponds into our bio-filtration system, which removes impurities and will eliminate the scent.  That system is weather dependent, and cannot operate until nighttime temperatures are warmer (consistently above about above 10 degrees Celsius).    However, we are also in the process of expanding and improving our system so that once the weather permits use of the bio-filter, the treatment process will be completed much faster than before.   

For more information please visit our Stormwater Systems and Wetlands fact sheet.