Local Government Magazine
Waste Management

War on waste

New Plymouth District Council is taking a bold approach in pursuit of its goal to become a zero waste district by 2040.

New Plymouth District Council (NPDC) is part of a team responsible for the development and installation of an enclosed flare stack, designed to cut greenhouse gas and odour emissions at New Plymouth’s Colson Road Landfill. 

Since it began operating in March 2018, use of the flare has resulted in more than 90 percent of captured landfill gas being burned off, meeting New Zealand’s National Environmental Standards for Air Quality and lessening the impact on the site’s neighbours in the process.

First opened to the public in the mid-1970s, the Colson Road site is a small-to-medium sized landfill that accepts waste from throughout the region, including the kerbside collections of the New Plymouth, Stratford and South Taranaki district councils.

Its physical location, close to popular Waiwhakaiho shopping centre, The Valley and about 500 metres from the nearest residential property, had previously resulted in the occasional report of a bad smell – usually on cold, still mornings.

Landfill gas is primarily made up of methane – a powerful greenhouse gas 20 to 60 times more powerful than CO². The gas occurs when organic waste such as food, garden waste, paper, cardboard and timber breaks down.

Due to the site nearing capacity, gas production at the Colson Road Landfill is currently at its peak, and, as a result, the successful implementation of an effective gas management solution was a priority for the region’s district councils.

Whilst all new landfills in New Zealand are required to have a method for capturing and burning gas, the installation of a flare and pipeline system into an existing landfill – one that remains operational – had its challenges.

At the Colson Road Landfill, a fully-enclosed flare with an eight-metre-stack was installed, meaning no flame or light can be seen from the outside while the flare is in use.

Before it could be installed, however, the specific area in which the flare and pipeline would be located had to be capped, meaning soil was brought in and compacted. The system also needed to work in with the site’s existing leachate pipework, and, because the landfill remains operational, ongoing work is required to manage water getting into the pipes. 

To meet the National Environmental Standards for Air Quality, 99 percent of the elements within the landfill gas needs to be safely destroyed. The Colson Road Landfill flare is achieving those levels. Additionally, since the flare started in March last year, there have been no complaints about odour off-site.

NPDC has an ongoing approach to waste management that includes reducing the amount of waste that goes to landfill. Currently, about 40 percent of the material that goes to Colson Road Landfill could be recycled or composted instead.

This article was first published in the October 2018 issue of NZ Local Government Magazine.

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