Wastewater Treatment Plant

Crew replacing diffusers in Aeration Basin #2.
Updates re) Odour Issue
September 3, 2019

Why are there still odour issues near the waste water treatment plant? Is this what we should expect from now on?

The reason we are still experiencing odour issues around the wastewater treatment plant is because the required maintenance work is not yet completed. While this is an unpleasant situation, it is not permanent. We hope to have our maintenance work at the plant completed by the end of the week, at which time the second aeration basin will be put back on line.

Why is the maintenance work taking so long?

As we were preparing to put the second aeration basin on line, we discovered that the main valve, which controls the effluent flow out of the plant, was damaged. A new valve is on order and is scheduled to arrive on site on Wednesday, September 4th, for installation on Thursday, September 5th.  Once it is installed, we will be able to fill the second aeration basin over the weekend. This should take care of the current odour issue.

We apologize again for the extended odour issue. Please forward any questions you may have on this matter to dtardif@gibsons.ca.

August 27, 2019

Maintenance work in aeration Basin #2 has identified a piping air leak which will delay the start-up of that basin until the Labour Day weekend. However, odours at and around the plant are no longer an issue as Basin #1 has stabilized and is handling the full plant flow.

August 20, 2019

Apologies: First we would like to apologize for the odours that have been emanating from the Waste Water Treatment Plant (WWTP) over the last 8-9 days. We did make a judgment error in assuming that proceeding faster with emptying one of the aeration basins was going to reduce the length of time the maintenance work was going to impact the system. As mentioned earlier, we have learned from our mistakes and will let the neighborhood know of upcoming major maintenance work well beforehand in the future.

When is the best time to do this type of work? We chose summer to do the work since that is when we have the lowest volume of water flowing through the plant. The sanitary piping network that services the Town is not completely sealed from the rest of the environment, which means storm water is entering the system in many places (we refer to this problem as inflow and infiltration or I&I). To be able to handle the Town’s sanitary flows with only one aeration basin, we need to do this type of work outside of the rainy season. The next time we do similar work will be in late spring or early fall to avoid the monsoons and while the weather is cool.

What is the current status at the plant? The single operating aeration basin has almost recovered over the last 24 hour period, which means less offensive odours around the plant (please correct me if I am wrong). The maintenance work in the second aeration basin is well underway and will be tested for leaks late this evening and overnight. Our crews have been working long hours and over the weekend to reduce the length of the maintenance shutdown. We expect the second aeration basin to be back in operation tomorrow and the odour issues to be under control by Friday.

Do any of the odour issues experienced lately have anything to do with the Waste Water Treatment Plant upgrade? No. The upgrade work currently taking place is to give us a storage tank upstream of the plant to handle sudden surges in flow during winter storm conditions. The I&I issues we mentioned earlier can result in high peak flows during the winter storms making it difficult to operate the plant properly. Other aspects of the upgrade will consist in adding better instrumentation to the aeration basin for improved control of the process parameters.

We will continue posting similar updates on our website and Facebook page daily until the plant is back in full operation.


August 19, 2019

What is happening at the sewer treatment plant?

For the last week we have been preparing for a major maintenance shutdown taking place this week. The waste water treatment plant’s main components are the two large aeration basins used to “digest” the waste water entering the plant. The major maintenance work we are doing consists in replacing the 650 diffuser nozzles located at the bottom of one of the two aeration basins. This work is meant to improve the plant’s reliability. The diffuser replacements are typically scheduled to take place every 5 years, but this is the first time the work is being performed since the plant’s upgrade in 2006.

Why the smell? In our effort to complete the aeration basin maintenance work in a timely manner, we under-estimated the odourous effect that the transfer of “sludge” from one basin to the other would cause.

How long will this last? We expect the odour issue will continue for a couple more days as the aeration process works its course in the functioning aeration basin.

Why does it smell mostly in the evening? During the day, the prevailing breeze is from the ocean towards the land (wind goes up the mountain) while the evening breeze is from the shore to the ocean, causing odours from the plant to move down towards the ocean.

How often is this going to happen in the future? We plan on doing similar major maintenance work on the second aeration basin next year. However, you can expect a much less intrusive experience at that time since we have now learned several key points that will be put into practice.

We understand your frustration, and appreciate the major inconvenience this may cause to all who are affected.

We will be updating our web and Facebook pages daily over the next several days to keep all informed of the changes taking place at the plant.


In today’s modern society we have numerous uses for water, both around the home as well as in commercial or industrial operations. This water becomes wastewater once it has been “used” whether for washing dishes in a restaurant, flushing a toilet, or as part of a manufacturing process.

The Town of Gibsons operates and maintains the network of trunk sewers, pumping lift stations and a wastewater treatment plant that connects the Town’s sewer systems.

Liquid waste management has an effect on our environment and the livability of our community. If we don’t take care to handle and treat the many pollutants generated by human activities, the quality of our surrounding environment will suffer.

With the commissioning of the new Wastewater Treatment Plant in 2005, the Town is always striving to upgrade and optimize the workings of the plant to ensure the best possible effluent discharge that exceeds permit requirements and minimizes odour.