Testing Continues at East Clive Plant

Hastings District Council (HDC) will continue to divert domestic sewage to the milliscreen plant while it does further testing to reduce odour at the East Clive Wastewater Treatment Plant.

Water Service Manager Brett Chapman says the new Biological Trickling Filter (BTF) system is still in the commissioning stage.

“The bio-mass, which processes the domestic effluent, is building steadily within the tanks and the quality of the BTF discharge is much clearer than that from the milliscreen process,” Mr Chapman says.

“However, unrelated to the BTF process itself, there have been issues in certain conditions with odour drifting from the tops of the tanks where untreated effluent is exposed to the air.

“Testing before the plant was opened indicated that the odour would not be any greater than the existing smell from the enclosed milliscreen plant but this has not turned out to be the case.”

Hawke’s Bay Regional Council has granted HDC permission to divert domestic sewage to the existing milliscreen plant this week to allow continued testing and to reduce the smell, as Council did over the Christmas break.

HDC, in partnership with HBRC, is working hard to reduce the odour to acceptable levels and has put an action plan in place to address the issue.

Council is looking at a number of options to deal with the odour in the long term, including;

· Calming measures; such as installing a rubber apron to slow sewage flows into the tanks instead of cascading from the top of the distributors.
· Upstream treatment measures: investigating treatment measures further up the pipe, such as adding oxygen to keep the maturing effluent “fresh” until it gets to the treatment tanks. This may be a cost effective solution.
· Wind modeling: investigating wind deflectors on tops of the tanks to reduce disturbance.
· Covers: cap tanks to enclose the process and capture odours.

Affected neighbours are helping HDC and HBRC to monitor and report the odour emissions and HDC is keeping them regularly informed on the progress of the action plan.