Permanent signs in Tomahawk Rd, near Smaills Beach in
Dunedin, that warn against collecting shellfish should be
removed this year, as work to clean up Dunedin's sewage nears
The signs were expected to be taken down by September, when
the second stage of the Tahuna outfall and secondary
treatment plant was due to be completed.
But construction delays and technical issues mean the plant's
complex biological filter, which clarifies the sewage stream
so the ultraviolet disinfection system can have more effect,
was commissioned only this week.
Dunedin City Council water and waste services manager Dr
Laura McElhone said the ultraviolet treatment system itself
was commissioned late last year and test results showed it
was disinfecting more than 99% of the sewage stream.
She said the council wanted to be totally confident the
biological filter was working as it should before warning
signs were removed from beaches. An exact date for that to
happen was not available yesterday.
Since the $37 million, 1.1km Tahuna outfall pipe was
commissioned in January 2009, regular tests of water from
between Second Beach, near the St Clair pool, and Smaills
Beach have shown the water is safe for swimming.
Dr McElhone warned, however, that while beaches should no
longer be contaminated by sewage, there might still be issues
with pollution from other sources after the treatment plant
was fully operational.
A perfect example came yesterday as swimmers and surfers were
warned to avoid the waters around Lawyers Head until further
notice, after testing revealed high bacteria levels that were
probably due to natural environmental conditions, such as hot
weather and a high number of sea birds in the area. There was
no indication the contamination was linked to the treatment
plant, she said.
The council has previously warned there could be
contamination from farming activities and run-off into the
ocean, especially during heavy rains, once the signs are