Emergency work starts on sewage plant to stop spills

By TONY GEE

Emergency work is expected to start within a week at the Kawakawa sewage treatment plant to try to stop more effluent spills that have closed oyster farms in the Bay of Islands and put harvesting on hold.

Controlled and uncontrolled overflows from the plant this month, spilling partly treated and untreated sewage into the Kawakawa River, have closed oyster farms in the Upper Waikare Inlet.

"We're trying to get emergency work under way immediately," Far North District Council Mayor Yvonne Sharp said after a meeting with Northland Regional Council chairman Mark Farnsworth.

The work at Kawakawa involves enlarging an area above the plant's ponds to create storage capacity so that overflows of stormwater and effluent into the station can be pumped up into storage ponds instead of discharging into the Kawakawa River.

The district council has no consent for the new emergency work but will apply for it later from the regional council, Mrs Sharp said.

Stormwater infiltration into the sewerage system, either by accident or design from about 70 properties including Bay of Islands College and Bay of Islands Hospital at Kawakawa, is blamed by the district council for causing overflows and spills from the plant after heavy rain.

Mrs Sharp said property-owners affected were required to fix the problem within 42 days, otherwise the council would do it.

The matter has become urgent after another pump station spill last Thursday resulted in about 175 cu m of untreated sewage discharging over nearly two hours.

That followed an earlier, controlled spill from the station of partly-treated and heavily-diluted effluent. About 23,000 cu m was discharged into the Kawakawa River.

The council also plans to double treatment capacity at Kawakawa from 800 cu m of effluent to 1600 cu m daily. It has already spent $2.4 million on upgrading the plant.

Council utilities manager Anthony Earl said this would give extra capacity if a public sewerage scheme was needed for nearby Moerewa. It was in line with discussions with oyster farmers on long-term measures to minimise risks to their industry.

Mr Earl said that subject to any variations in resource consents, the project was expected to go to tender within two months.

At the same time, a suspected effluent discharge into a stream leading into Uruti Bay from a broken pipe joint at the Russell sewage treatment station has closed 22 oyster farms in nearby Orongo Bay.

A total of 26 farms are sitting out a 56-day oyster harvesting ban imposed by public health authorities.

Pending any further adverse results from the latest Kawakawa discharge, four Upper Waikare Inlet farms must wait until August 28 to resume oyster harvests, while those closed at Orongo Bay because of the Russell pipe breakage cannot resume harvesting for export until September 3.

Northland Health shellfish protection co-ordinator Neil Silver said harvest closures were necessary to allow the oysters time to expel any contamination or pollution they may have taken in from the effluent spillages.

As bivalve filter feeders, oysters had a natural ability to accumulate pathogens (disease-causing agents) in water.

"I'd like to be able to tell the Orongo Bay and Upper Waikare farmers to get their product out and onto the market but there's nothing I can do to get a shortened period of closure," Mr Silver said.

Alex Clifford, who has three farm leases in Orongo Bay with "thousands of dozens" of oysters currently going nowhere, says there was a high standard to maintain in selling oysters on the international market.

"Those standards have to be kept," he said.

"The product doesn't die [during harvest closure]. It just gets bigger."

Cost of pollution

A total of 26 farms are closed

22 in Orongo Bay (cannot resume harvesting for export until September 3).

Four in Upper Waikare Inlet (harvesting on hold until August 28).