Construction of the Odour Control Facility in King Edward Park was completed in 2002. The facility used a biofilter, which consisted of a bed of root-wood chips built at ground level. Odourous air from a trunk sewer under Mill Creek was extracted with fans, depressurizing the sewer, and blown through the biofilter. The treated air was then released at ground level through the porous bed of wood chips.
The initial performance of the facility was reasonably good, however there were complaints from nearby residents about its effectiveness. As a result, a local advisory committee was formed to come up with possible solutions to the problem.
Tests throughout 2003 showed that the biofilter did remove a large percentage of hydrogen sulfide gas, resulting in releases that were below the odour threshold concentration limits. However, there were other gases that could not be treated with a biofilter. It is possible that there are other natural occurring biological processes in sewers that produce these gaseous compounds, or it is possible that specific chemical discharges from industrial areas upstream of this location produced these gases.
In 2004 and 2005, a containment structure was built over the biofilter bed. The fans in the structure pull the treated gas through a secondary treatment that uses activated carbon. This “polishing scrubber” treats all residual gases that the biofilter could not treat. The entire facility was constructed under ground, with a landscaped hill covering the facility, keeping with its park setting.
After the extensive testing of the treatment process in 2005 confirmed the effectiveness of the facility, the advisory group was disbanded in 2006.
From time to time, there have been minor complaints from nearby residents about the facility’s performance. The cause of the problems have been identified and rectified.
For more information about the previous activities Utility Services has undertaken at this site, or related to sewer odours, please refer to the archived webpage, or check our Sewer Odours webpage for current information.