Innovative landfill gas control at Garden Island Landfill
Collaboration with a leading construction services company and a government waste management authority.
Pacific Environment was selected to be a sub-consultant to a leading construction services company who were commissioned by the client, a government waste management authority.
Previous investigations had demonstrated that Landfill Gas (LFG) is still in an active stage of generation, and given the age and size of the site, landfill gas was expected to be produced beyond 2030. Surface emissions of landfill gas had been measured at various locations and sub-surface lateral emissions also required control at two locations due to historic construction practices at the site boundaries. These were required to control emissions to mitigate the potential human health and environmental risksat these discrete locations to maintain a safe, positive land use balance between all relevant stakeholders.
A government waste management authority wanted to mitigate the risks associated with the generation and migration of landfill gas off-site by installation and management of a perimeter Gas Collection System (GCS) that would effectively extract and safely combust landfill gas using appropriate flaring technology. The Gas Collection System and flaring plant was required to be designed, installed and commissioned in approximately 12 months and prior the end of August 2015.
Pacific Environment produced a methodology for managing LFG with a site specific approach to design, construction and operating of an effective system to control LFG emissions in the areas of concern to meet performance requirements the government agency had approved by EPA in its LFG management plan. The design and installation of these features has resulted in these criteria being met.
The design, installation, trial, data analysis, operation and validation data obtained by Pacific Environment were used to get the desired result for the client to help them meet their goals.
Due to forecast declining flows and concentration of methane, and the requirement to manage the LFG in the longer term, a low calorific flare (Lo-Cal) that could combust gas safely with a lower concentration than a standard high calorific flare was chosen for the site. The Lo-CalTMflare supplied by Biogas Systems Australia and was demonstrated to combust methane between 12 and 50 %v/v methane, making it suitable for this site and into the future with the declining methane concentration.
The flare has proved to work continuously at several sites in Europe. The use of this specific flare will result in minimal manual intervention (call-outs) and mitigating risk to Council by reducing potential off-site migration. The flare is the only available technology that can burn gas with methane concentrations below 20% at a flare temperature for 1100 deg C. This temperature is required to be compliant with the Emission Reduction Fund methodology.
Therefore, our approach has the potential for sustainable gas management in the long-term.
We are supplying the Low calorific flare from Europe through Australian company Biogas Systems Australia. This will be the first time this technology has been successfully used in Australia.