28 Sep 2020

A new ‘recipe’ for making compost at the organics processing plant in Bromley could hold the key to reducing the suburb’s odour issues.

The new recipe has been formulated over the past three months following a series of small scale trials at the Living Earth plant.

“As it takes about 12 weeks for material to go through the composting process, we won’t know exactly what impact the new recipe has had on the odour situation until the end of October,’’ says Christchurch City Council City Services General Manager David Adamson.

“However, tests that we have done show the new compost recipe gives off considerably less potentially odorous gases than the old compost recipe so there are promising indicators it will make a positive difference.

“We appreciate there has not been a significant change to odour in the wider area so far but are hopeful that Bromley residents will gradually start to notice the odour issues dissipating as the new compost recipe works through the facility,'' Mr Adamson says.

In addition to introducing a new compost recipe, several other changes have been made at the Living Earth plant over the past three months. These changes, which are all designed to help reduce odours from the plant, include:

  • Introducing additional water misters.
  • Increasing the turning frequency of the windrows.
  • Amending irrigation levels
  • Changing the acidity levels and the ratio of carbon to nitrogen.
  • Changing the temperature within the tunnels
  • Increasing the porosity of the material in the tunnels to increase airflow.

The Living Earth plant is one of two Council-owned facilities that were identified earlier this year as contributing to the long-standing odour issues in Bromley. The other facility was the EcoDrop Transfer Station, which is operated by EcoCentral.

Mr Adamson says new ‘housekeeping’ processes put in place at the transfer station in mid June have significantly reduced the odour coming from that facility.

An electronic ‘nose’ placed in the roof area of the transfer station pit had detected a 40 per cent reduction in odour since the changes were made.

Mr Adamson says the Council’s plans to survey residents in the Bromley area in the coming weeks about the odour issues and whether they have noticed an improvement in the air quality

“Some residents in the Bromley area are very diligent about reporting odours through the Smelt-it app. But we need to talk to the wider community to get their views on whether the odour management work we have been doing is making a difference.

“The findings of that survey will help to determine our next steps, with potential options for redeveloping the composting facility due to be put to Councillors by November this year.’’ Mr Adamson says.

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