Engineered Wetlands for Glycol-Contaminated Stormwater Treatment

Annually, Edmonton International Airport must treat glycol-contaminated stormwater collected and stored in a separate pond after the winter months. Until recently, the contaminated stormwater was discharged to the environment after treatment in a constructed wetland. However, airport expansions and increased air traffic have continued to increase the amount of glycol-contaminated water requiring treatment, challenging the capabilities of the existing constructed wetland system. The treatment system required an upgrade to enable the full treatment of the contaminated stormwater within the Edmonton Airports' required time of sixty days while reliably achieving high effluent quality. The system also needed to be constructed within the footprint of the constructed wetland, be able to withstand Edmonton's cold climate, be simple and reliable to operate, and not exceed a $3.0 million budget. Two of the constructed wetland trains were upgraded into two engineered wetland trains that consisted of vertical and horizontal aerated gravel beds cells. Two years of operation of the engineered wetland showed that the system reliably achieved effluent quality well below the regulatory approval limits while achieving the required system capacity.