A Dunedin City Council staff member examines a peephole
into the incinerator at the Tahuna Treatment Plant. Photo
from ODT files.
The unexpected granting of a 35-year air discharge
consent for incinerating solids left over after the treatment
of Dunedin's sewage has saved the Dunedin City Council $10
Putting in an effective and environmentally sustainable
system for the disposal of the solids was the final step in
the 20-year upgrade of the Tahuna Waste Water Treatment
Initially, the existing consent was not expected to be
renewed with incinerator emissions included and the council
had spent significant time since 2010 evaluating different
systems for disposing of the solids.
A report to councillors for consideration during annual plan
discussions yesterday says using the incinerator has several
benefits, including a 50% reduction in the number of trips
with solids to the Green Island landfill, where it is dumped
or fed into a gas-powered electricity generator.
The option effectively saves the council $10 million, because
existing equipment should be able to be used for the upgrade
required for the incinerator.
It had set aside $14.5 million over the next three years to
build a facility for new disposal technology, but, to date,
no suitable alternative technologies for such a process have
The consent, which was issued by the Otago Regional Council
with agreement ash would be removed during the combustion
process, meaning much more of the waste can be incinerated.
Councillors yesterday agreed to the plan, with Cr Jinty
MacTavish expressing some doubts about the carbon footprint
involved with using an incinerator.
She said she did not feel ''comfortable'' endorsing staff
recommendations based on the level of information in the
''There is a need for all of us to be aware of the carbon
emissions that we are locking our city into.''
Water and waste group manager Laura McElhone assured Cr
MacTavish staff would continue to look for better energy