Dump gas an 'explosive risk': GNWT
Government calls on city to monitor methane levels at solid waste facility
Randi Beers
Northern News Services
Published Friday, October 3, 2014
SOMBA K'E/YELLOWKNIFE
The territorial government wants the city, citing a possible explosive hazard, to start monitoring methane gas levels at the Yellowknife Solid Waste Facility.
The baling facility is one of the major structures at the Yellowknife Solid Waste Facility where the department of Environment and Natural Resources is concerned methane gas could build up and create an explosive hazard, according to documents submitted to the Mackenzie Land and Water Board. - Randi Beers/NNSL photo |
According to documents submitted to the Mackenzie Land and Water Board last month, a Yellowknife landfill gas assessment completed by consulting company Jaques Whitford in 2005 found one of five gas samples taken at the landfill that year had methane quantities in the explosive range. The report indicated "significant health and safety concerns, including explosive risk."
The documents indicate the Department of Environment and Natural Resources (ENR) recommended the city undertake a landfill gas monitoring program beginning in 2009, but the city hasn't moved on this recommendation yet.
Methane gas is produced by all landfills as a result of decomposing organic waste. It can travel underground and seep into enclosed places such as buildings or low-lying areas where it can reach concentrations that create an explosive hazard.
Chris Greencorn, the city's director of public works, told Yellowknifer the city doesn't currently monitor landfill gas at the dump.
He said the city has always intended to do a gas monitoring plan as part of its final landfill closure activities later in the decade, but the issue hasn't been a priority because there are no territorial guidelines to regulate how municipalities monitor landfill gas.
"We fully intend to comply with our water licence, but doing those things take time," he said.
According to Greencorn, there is only one structure where methane could possibly accumulate at the landfill site - a baling facility where recycled material is processed. The city does not monitor methane levels inside the baling facility, but Greencorn did point out the structure has good ventilation.
"We won't disregard ENR's comments, but we will get it updated to make sure our site is safe and within the environmental regulation," he said.
Concerns over methane gas buildup due to the expansion of the city's composting facility spurred ENR to
reach out to John Muller, a landfill gas specialist based in Toronto, this summer.
The department asked Muller to look over the city's designs for the expansion of the facility above an older part of the landfill because the department had concerns the structure would not allow for the escape of methane gas.
According to a document submitted to the Mackenzie Land and Water Board, the department asked Muller whether it's safe for the city to proceed with expanding its compost facility in the manner it has proposed.
The city had already started the expansion project when ENR reached out to Muller.
"It's unlikely it would cause an explosion at the site," said Shannon Ripley, waste reduction specialist with ENR.
"But it's important to monitor where that methane is going and prevent it from entering buildings on site or collecting in low lying areas and not let it get to that level where it could be explosive."
In an e-mail to ENR, Muller stated he had concerns about the construction drawings, particularly that they didn't make it clear whether the project allowed for proper venting of methane through "side slopes" and recommended the city install vertical vents.
Greencorn said the compost facility's design does allow for the gas to escape.
Muller included a number of recommendations to the city in his response. He wrote the city should monitor where methane moves below the surface of the ground because it could move offsite and collect in nearby buildings, creating an explosive hazard.
He also stated the effect of permafrost on the movement of methane should be considered in the design of the city's gas monitoring plan.
The city has indicated it plans to complete a landfill gas study in 2016 or 2017.
The board has directed the city to submit further information about its landfill gas management by Oct. 14.
