A high-tech steam clean might be just the ticket to remediate the soil at the Greenwich-Mohawk brownfield site.
During a committee of the whole meeting on Monday night, Geoscientist Steve Desroches of Golder Associates told Brantford city councillors about steam enhanced extraction, a process which involves injections of steam to heat soil saturated with petroleum hydrocarbons, the most dangerous contaminant in terms of risk to future development.
The heat loosens the contaminant particles, which are drawn to water in the soil and removed via a vacuum extraction system. The extracted mixture is treated above ground and rendered inert.
Steam enhanced extraction is an “incision technology” similar to what is used in oil extraction that could represent a cost effective way to remove the mobile and volatile compounds which pose the highest risk to humans and groundwater sources, Desroches said.
On-site remediation is preferable to traditional excavation methods since it is cheaper to treat the soil at the source than to transport it for cleaning and disposal elsewhere. The steam heat increases biodegradation rates in the soil, employing naturally occurring bacteria to help further clean the land.
The steam method would not be a cure-all for the entire site. The extraction process targets contaminants derived from oil and tar, but will not remove heavy metal contaminants in the soil. Those can either be covered over or removed later using another method, Desroches said.
If approved by council and the Ministry of the Environment, the brownfield remediation would be the first steam enhanced extraction project in Ontario. A recent thermal cleaning project in Peterborough used electricity to heat the soil, running up energy costs.
Meeting as committee of the whole, council approved $15,508 in cash and nearly $24,000 worth of staff time toward a pilot project that will see Netherlands-based Groundwater Technology remediate a plot of soil at 347 Greenwich St. using the steam method.
A successful lab test done earlier this year removed between 84 and 100 percent of contaminants from a small portion of brownfield soil.
Groundwater will now conduct a field test on 600 to 800 cubic metres of soil – approximately 3,000 square feet – to see how effective the process is on location.
An additional $130,845 in the form of a Green Municipal Fund feasibility grant from the Federation of Canadian Municipalities will also fund the six to eight-week pilot project, expected to begin this fall if council gives its approval.
Sponsored by the Dutch government, the company will contribute approximately $76,665 to the project, which has a total estimated price tag of $261,690.
The steam technology is “an innovative and sustainable means to clean up a portion of a vacant brownfield site that has good potential for development in the future,” said a report prepared by city staff.
“The demonstration project could raise a positive profile for Brantford, both provincially and nationally, and would be an educational opportunity for the community in learning about using environmentally sustainable soil remediation techniques in Canada.”