Worms to rescue waterway?

March 18 2012

The CHB Council is (inch)worming its way toward progress in cleaning up its sewage discharge into the Tukituki.

On Tuesday the Council will hold a special session to consider replacing its proposed ‘effluent to land’ sewage treatment scheme with a less expensive scheme that would discharge substantially cleaner effluent into the Tukituki … using worm farms to clean the effluent.

The alternative scheme is less expensive and is based on a proposal made to CHB several years (and consultants) ago. At the time, the worm clean-up was less tested in New Zealand and so was rejected. However, recent data from such schemes in New Zealand seem to indicate that the process could in fact put CHB in full compliance with the more stringent water quality standards the Environment Court has said the two sewage treatment facilities must meet by 2014.

Faced with 20 submissions opposing the consent application CHB has just filed for the ‘effluent to land’ scheme, it appears CHB officials are worried that conditions imposed during an appeal of that application might lead to even more expense, over and above the higher costs now anticipated for the ‘effluent to land’ plan after new consultants updated the construction estimates.

So, from an environmental standpoint, the ‘effluent to land’ approach involves putting 50% less (but essentially untreated) effluent into the river, while the worm clean-up would arguably reduce contaminants substantially (readily meeting tougher standards if the performance results reported hold up), but still discharge the treated effluent into the river.

The worm clean-up option deserves consideration (if the Council indeed decides to entertain it at its extraordinary Tuesday session). Here’s the staff report.

My sense is that key environmental objectors to the land-based scheme might well prefer the worms to the forest discharge (at least as the latter now stands). That said, the worm scheme will need to be vetted thoroughly, with plenty of evidence produced as to its viability.

Effectively, the matter must be decided during CHB’s long term plan review process … which must end with LTP adoption by June 30.

ENDS

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