Council working to remedy treatment plant issues - 16/10/2012

“We have been working really hard to deal with ongoing issues at the treatment plant and we thought we were fairly well on track until there was a sudden spike in compliance problems late last year,” Mayor Annette Main said.

“These problems have resulted in us being unable to comply with the conditions around our discharge through the ocean outfall and as a result of our most recent compliance report to Horizons Regional Council, they have now issued us with significant non-compliance because we are not meeting the conditions of our resource consent.

“No public health issues have been raised as a result, but I believe we need to be absolutely sure this remains the case. Consequently, we are increasing water quality testing over and above what is required by our resource consent by testing samples taken from both Castlecliff and South beaches. These results are expected on Tuesday, October 16. Previous shellfish monitoring has shown that there has been no cause for any public health concerns.”

There have been ongoing problems with the effective operation of the treatment plant since it was commissioned in 2007, with the aerators causing particular concerns. A November 2011 independent report recommended some tests and options to improve the health of the plant. Pilot tests were undertaken earlier this year.

In early 2012 more of the aerators failed and a survey of both ponds revealed the sludge layer at the bottom of the ponds was more than four metres deep in places; a situation not expected to be reached for several more years.

Several weeks ago 12 more aerators failed, leaving only seven of the 23 operating, with the gap in compliance widening further.

“Our community has invested $120M in the entire wastewater project, of which the treatment plant is a small but important part. We are committed to protecting that investment and are putting in place plans to ensure we can comply with our resource consent.

“We have brought forward some work that was planned for 2015 which will begin stabilising the plant and reducing the levels of sludge, faecal coliforms and suspended solids. This work, which is called bioaugmentation, basically involves growing ‘good bugs’ in a container at the plant and then introducing them into the ponds. We believe has a greater chance of success and is more sustainable long-term than treating the problems by chemical methods. The equipment is expected to be on site by the end of October. We expect to see improved results before Christmas 2012.

“Our priority is to stop the decline in health of the wastewater treatment ponds and return them to a steady state in December and shortly after get the outflow to acceptable consent compliance levels.”

Background information on the wastewater treatment plant