As many local residents know, the stormwater facility adjacent to Dusty Miller Crescent in Riverside South has been emitting “rotten egg” or “sulphur” odours during the winter months for the past several years. City staff investigated the phenomenon with the assistance of the University of Ottawa, and staff are now in a position to implement a solution to resolve the issue. A summary of the issue and the proposed solution are summarized below.
Research conducted by the University of Ottawa determined that the “sulphur” odours are caused by hydrogen sulfide gas that is produced in the stormwater facility by sulfate reducing bacteria. This bacteria is naturally occurring and thrives in this particular facility as a result of a number of unique watershed characteristics that results in water with low dissolved oxygen levels. The University’s study recommended increasing dissolved oxygen levels using an aeration system, and staff are moving forward to implement a mechanical pump aeration solution.
To date, a preliminary design for an aeration system is complete, and staff are now in a position to share this preliminary design with the Community. The attached ‘pdf’ plan provides the general layout of the following aeration system components:
- Electrical service to the site from Limebank Road.
- Precast concrete building on site containing a compressed air blower unit as well as a control panel.
- Eight (8) aeration units that will sit on the bottom of the pond and will release air bubbles into the water.
In terms of schedule, construction is planned to begin in July/August 2018 and will be complete in September/October 2018. Portions of the existing pathway network will be closed temporarily during the construction period to protect the public from the work area. All temporary pathway closures will be communicated to the community prior to the work commencing.
When the aeration system is complete and functioning, residents will notice bubbles on the surface above each aeration unit. The system components will be located and enclosed so that resident’s will not be exposed to any noise. During winter months, the aeration units will prevent ice from forming in the immediate areas of the aeration units, and signs will be installed around the facility reminding the public not to walk on the ice.
In summary, the aeration system will provide better mixing of stormwater within the facility and will increase the dissolved oxygen levels. These two benefits will prevent the conditions necessary for the production of hydrogen sulfide gas.
We encourage any questions and or comments regarding the preliminary aeration design from the local community residents. Questions and/or comments can be directed to:
Ryan Polkinghorne, P.Eng.
Project Manager, Stormwater Engineering Support Unit
Parks, Forestry and Stormwater Services Branch, City of Ottawa
Phone: 613-580-2400 ext. 28008