Sweet success: Using molasses to clean up a contaminated landfill

Did you know that nature has its own ways of cleaning up contamination? We spoke to Jean-Fran?ois Dion, a senior environmental specialist with the Contaminated Sites Centre of Expertise for the National Capital Region at Public Services and Procurement Canada (PSPC), about how PSPC uses these natural processes in its work at the Gloucester Landfill in Ontario through an eco-friendly method called bioremediation. Jean-Fran?ois says, "A lot of people expect that to decontaminate a site, you need to use a chemical to destroy the contamination. So when they find out that nature has a solution for that, they're surprised."

Contaminated sites are places where the soil or groundwater has been polluted by hazardous chemicals or substances, for example, at old gas stations, dry cleaners, factories, airports, landfills or many other types of industrial lands where harmful contaminants have been released into the environment.

Darragh Kilroy, Manager of the Centre of Expertise, explains his team's role: "Departments come to us and they say, 'Hey, we think we might have an environmental problem with the soil or groundwater at our site, but we don't know exactly what the issue is or have the expertise to fix it. Can you help us?' So our role as a centre of expertise within PSPC is to advise them."

Jean-Fran?ois uses his extensive experience as an environmental geologist to liaise with the client department and the environmental engineers who perform the work. "The experts we bring in are highly technical, and the client is usually not. My role is to identify the project requirements, create the scope of the work, and oversee the project to ensure it's carried out properly."

A collaborative effort

Darragh's team has been working with Transport Canada (TC) for many years to help TC remove the Gloucester Landfill from the federal contaminated sites registry. In 2013, PSPC implemented a pilot project to inject a molasses solution into the contaminated aquifer at the landfill, feeding the solution to the Dehalococcoides bacteria that break down contaminants. Aquifers are saturated layers of rock or soil underground that store and transmit water. The success of the pilot led to the implementation of full-scale work beginning in 2019.

Jean-Fran?ois credits the strong collaboration and trust between TC, PSPC and the environmental engineer for the success of the initiative: "We worked very well together to move forward and achieve our goals."

The team has optimized the injection solution and, thanks to 3D modelling technology, now targets the injections to the exact location of the contamination several times a year. Analyses of the groundwater at the Gloucester Landfill are showing incredible improvements.

Jean-Fran?ois projects that, at current rates of progress, a site that was once significantly polluted will no longer be an environmental risk in just a few years. "We've made a lot of progress in the last couple of years, and we're hopeful that we will see the end of this project in the next year or so. I'm very proud of that because a lot of people worked on this before me, and we're finally seeing the end."

The challenges of the Gloucester Landfill

From 1969 to 1980, PSPC tried different approaches to clean the site, such as a groundwater extraction and treatment system that was built in 1991 and operated until it reached the end of its service life in 2003. Since those early years, the technology used for identifying and cleaning contaminated sites has progressed from very basic methods to highly advanced processes, using cutting-edge technologies adapted to the unique demands of each site. For example, membrane interface probes and laser-induced fluorescence can provide real-time information on soil contamination and help create 3D models of subsurface conditions.

Darragh explains that these sensors measure the properties of the soil in almost real time as the team drills down, which gives a good indication of the extent of the contamination in that soil profile. They are great tools to help the team guide the molasses injections and understand how remediation is progressing.

He adds, "The Gloucester Landfill is the most complex site that we have because it's an old chemical landfill. Only technologies developed in the last 10 years and implemented on this site have helped us solve the problems at this landfill. These new methods help us get a high-definition picture of what's happening underground, so we can pinpoint the exact location of the contamination."

The success of the bioremediation of the Gloucester Landfill has proven the effectiveness of sustainable solutions for environmental cleanup.

Safeguarding the health of future generations

PSPC works with a variety of departments to support the identification, remediation and management of contaminated sites. Bioremediation is just one example of how innovative environmental technology is being used by the department to protect and safeguard the health of future generations and the ecosystems of tomorrow.

Read about the action plan for contaminated sites and discover how the Government of Canada is taking action to properly manage federal contaminated sites.

To learn more about PSPC employees, projects and services making a difference for Canadians, read other articles on Our stories.

You can also read the accessible version of this article on our website.