Dealing with the aftermath 

City still monitoring old Cook Road dump 

 

Laurent Robillard-Cardinal

Gatineau’s executive committee granted a contract, March 25, to Biothermica Technologies Inc. to estimate landfill gas emissions at the old Cook Road landfill site in Aylmer and the former La Baie dump in Pointe-Gatineau. The three-year contract has renewal options.

 

The two-part contract, costing about $35,100, is a renewal of an existing service which monitors landfill gas at the old Cook Road dump, especially any migration of the gas.

 

Although the Cook landfill closed years ago, it remains active as Roberto M. Narbaitz, University of Ottawa engineering professor, explained.  “Landfills take all kinds of waste; a substantial part is food and garden waste which are biodegradable. The landfill has bacteria that decompose organic matter and produce CO2 and methane gas. The gas is produced over a very long time. It takes some landfills 50 years to become safe,” said Narbaitz.

 

“The danger comes from the migration of gas off-site. This gas is maybe 50% methane, 50% CO2. Methane, which is heavier than air, stays in the ground and migrates outward from the landfill, which itself is like a methane-producing machine. The danger is if you reach 5 to 15% of methane in a building (as it remains explosive). About 30 to 40 years ago, there were a few farmhouses which exploded,” added Narbaitz.

 

As methane is like natural gas, it is flammable. Thus it’s important to collect the gas inside landfills so it doesn’t spread.

 

Gatineau uses a collection system that captures the gas and burns it off via 'flaring'. Narbaitz visited the Cook dump half a dozen years ago, and says, “Is it worthwhile to keep the system in operation so there’s no worrying about liability. The city has a nice system with air-driven pumps so there’s no risk of explosion within the landfill itself. They’ve done a decent job.” 

 

The city could burn the gas to produce electricity as do some regional dumps, but as Narbaitz explained, the 

financial cost is high. “It’s probably no longer financially viable as the [discontinued] dump has already lost a lot of its gas.” The city also monitors and controls any water going through the dump.

 

Water migration

 

As many North Aylmer residents recall, the Cook landfill caused many headaches in the 1990’s. According to environmentalist Ian Huggett’s 2002 estimation, the Cook Road dump contaminated wells in a neighbouring homes. This forced many North Aylmer residents to connect to the city’s water and sewer system. 

 

Today, theoretically, no rain water can enter the landfill because the top has been covered with an impermeable layer, but the sand bottom is permeable. Water running through the dump can pick up contaminants from old waste. “In the 1990’s the city dug several (protector) wells in a line to pump out this groundwater and treat it at a nearby facility,” explained Narbaitz. He believes this control system is still necessary for environmental reasons. 

 

The Cook Road dump is considered to be the single worst environmental disaster in the modern Outaouais by many. With today’s know-how it’s likely the contamination of wells could have been avoided – mainly by using an impermeable bottom layer.