Cleanup of toxic stream to start soon

A cleanup of New Zealand's most polluted waterway will begin this summer after city and regional councillors approved a $500,000 trial.

Waiwhetu Stream in Lower Hutt was, till the late 1970s, the site of unconstrained dumping of toxic chemicals from nearby factories. Its legacy is high concentrations of lead, copper, arsenic, zinc, copper mercury and the insecticide ddt in the stream's sediment.

The stream has little aquatic life and is unsafe for swimming.

Greater Wellington regional council and Hutt City Council officers have been developing plans to remove the stream's toxic trash, with the aim of returning it to the pristine state it once enjoyed.

Despite strong community support, cleanup plans almost came unstuck this year when the Environment Ministry said half its funding could be lost if all the money was not spent in one financial year.

Lower Hutt Mayor David Ogden said the dispute had now been sorted out, with the ministry agreeing to pay $2.9 million of the estimated $6 million cost. The city and regional councils would share the remainder. Councillors have now approved spending $500,000 to test whether a proposed extraction procedure would clean up the stream.

Regional councillor Prue Lamason, who has lived near the stream for more than 50 years, was pleased that, after years of talk, work would finally begin.

"It's wonderful. I'm extremely pleased. People will soon see something is happening."

Project manager John Eyles said a trial was needed, as the councils needed to know the method would work before committing to full funding. The trial would be carried out near the Bell Rd bridge.

Sheet pile walls would be installed across the stream, pumps would then take stream flows away from the area, allowing contaminated material to be excavated and dumped at the Silverstream landfill.

Mr Eyles said the work would take place in February and March and, if successful, a full cleanup could be done next summer.

The stream is also a flood risk, but Mr Eyles said flood mitigation work could not start till all the contaminated material was removed.