The Porirua City Council is to donate nearly $40,000 to an environmental cause after a "massive" spill of partly treated sewage south of Titahi Bay.
It was estimated the volume was equivalent to the daily discharge expected from a town of 40,000 people, although the Porirua discharge last year was diluted by stormwater.
The council went to the Environment Court yesterday, with prosecuting authority the Greater Wellington Regional Council having agreed to a proposed penalty of $25,000.
Judge Brian Dwyer said he was happy for the parties to propose a sentence but the suggested sum was "grossly inadequate" for the Porirua council's significant carelessness, which caused a massive discharge.
The judge thought the penalty should be proportionate to what would otherwise be an appropriate fine and the fact the money would come from ratepayers did not change that.
But lawyers for both sides suggested that, since Porirua ratepayers were also ratepayers for the Greater Wellington Regional Council, a conventional sentencing approach might not apply.
The regional council's lawyer, Tom Gilbert, said Porirua's response had been exemplary and the environment would end up better as a result.
The donation of $39,375 is to go to the restoration of Takapuwahia stream, at Titahi Bay, which was not affected by the spill.
The Porirua council will be convicted and discharged once the donation is made.
A combination of events caused the spill. A sewer broke when heavy rain washed out part of a bank of Kenepuru Stream, which let stormwater enter the sewer.
At the time, the capacity of the council's wastewater treatment plant was 40 per cent less than normal because maintenance was being done. A partly blocked grate reduced the flow to the part of the plant that was still working.
Partly treated wastewater overflowed and entered stormwater drains that flowed into a small stream leading to Tirau Bay, south of Titahi Bay. The stream became toxic to aquatic life and the bay was unsafe for recreation, including gathering shellfish.
A trainee plant operator had noticed the overflow about 9am on October 12 but assumed the stormwater drains would lead to the plant's regular outfall, not into the stream. He noted it in a logbook and left.
Soon after, a member of the public told the regional council the stream beneath the plant was brown and smelled like sewage. The overflow stopped about 5.30pm.
A brown plume stretched about 100 metres into the sea and smelled strongly of grease and fat.
- The Dominion Post
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