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Review of operations at the Biosolid Composter Plant.

30 October 2014

Operations at the Biosolid Composter in Whitianga will cease in November while we take time to look at how we can improve its financial viability. A decision will be made by April 2015 as to whether to reinstate operations or decommission the plant.

The Composter, which mixes green waste with biosolids (mainly from the Whitianga Wastewater Treatment Plant) was set up to produce Aa grade compost.

"While the composter has shown good operational results and is producing grade Aa compost, which we've been using on our Council parks and reserves, we now need to do a more in-depth assessment on its cost benefits," says Infrastructure Manager Bruce Hinson.

As part of our 2015-2025 Long-Term-Planning we've been reviewing the viability of the Composter, and commissioned an independent report to assess the cost benefits. The report was presented to Council's Infrastructure Committee this week. The report says there's no significant financial benefit to retain the composting operation and it's cheaper to send biosolids to landfill rather than compost.

The independent report looked at the original 2007 Business Case for setting up the Composter, as well as modelling several different scenarios which compared sending waste to landfill or using the Biosolid Composter. The report shows that in all scenarios it's cheaper to send waste to landfill.

To read the independent report on the viability of the Composter click here to go to the 29 October Infastructure Committee Meeting Agenda P16.

"The original 2007 Business Case said the Composter would save money by taking biosolids out of landfill and turning it into compost," says Mr Hinson. "It assumed that landfill costs would increase and the fact is, this just hasn't happened," he says. "The amount of compost the Plant is producing, while being used on our parks and reserves, right now doesn't financially justify its on-going operation costs."

"It's costing us more to produce compost from the Biosolid Composter than what we can buy it for commercially," says Mr Hinson.

"The prudent thing to do is to stop the Composter now and re-evaluate its viability to see if there is financial benefit for us to turn it back on," says Mayor Glenn Leach. "We need to get some definite figures around the volume and costs for producing the compost, as well as understanding more fully the financial implications if we decide to turn it back on or decommission the Composter."

If a robust market can be identified, then this may make the use of the composter more viable.  It is not clear that this market exists, however, further investigations into this are underway.

Council's Infrastructure Committee resolved at its meeting this week that staff should now come back to the Committee by April with detailed figures on compost volumes, along with a decommissioning plan for the Composter and possible options for re-use of the Whitianga site. It's also recommended Council's Audit Committee consider any future financial risk to ratepayers.

The 2007 Business Case can be viewed by clicking on the right-hand side of this page.


Backgrounder on the Biosolid Composter

The Biosolid Composter Project stemmed from a business case back in 2007 looking at how Council could sustainably manage and investigate environmental benefits using biosolids taken from our Wastewater Treatment Plants on the Eastern Seaboard. What was happening was that biosolids was being taken off the Coromandel to landfill at a cost. Investigations found mixing biosolids from the Treatment Plants with green waste (mulch, grass etc) could produce Grade Aa compost and long-term could save money as the assumption was landfill costs would increase long term. 

An 18-month temporary trial was set up in 2009 in Tairua of the Biosolid Composter to see if it could produce Grade As compost that we could use on our Parks and Reserves. This was successful.

The plant was moved to a permanent site in Whitianga in August 2012. Part of the resource consent, once the Plant was operational in Whitianga, was that Grade Aa compost had to be made, which for the first eight months, we could use only on our parks and reserves.