Sewage risk at summer beaches

Sewage will be pumped into the sea off Waiwhakaiho this summer
Sewage will be pumped into the sea off Waiwhakaiho this summer

News half of New Plymouth's sewage will be pumped into the ocean just 450m off Waiwhakaiho has surfers fuming.

The New Plymouth District Council has issued a warning to beachgoers after announcing one of its carousel  plant's two aeration basins would be taken out of service from next Monday so it could be emptied of 20 years' accumulated silt and then upgraded.

During the four months that this work will take to complete, at a time when Taranaki's residents flock to the beach, only half the sewage going into the plant will be fully treated.

The rest will be screened to remove "material" larger than 3 millimetres, disinfected, then piped out to sea through the Waiwhakaiho outfall, near the popular Fitzroy and Bell Block

Waiwhakaiho is one of the region's top surf spots and one that is protected under the Resource Management Act, Surfbreak Protection Society vice-president Allen Pidwell said.

Mr Pidwell said the act protected certain surf breaks from adverse effects and water quality was one.

The New Plymouth Surf Riders Club and Surfing Taranaki will meet this week to discuss potential action, Mr Pidwell said.

"There's no doubt the plant needs a clean, but Waiwhakaiho is protected and we're just wondering whether the council has even thought about this," he said.

"It's not very far out and it's close to the groyne (another surf break)."

Lawyer and surfbreak protection society member Scott Grieve said councils sometimes had special consents to dump waste in emergencies.

The council is warning that there will be a higher risk of illness and skin irritation from swimming and gathering shellfish.

"We encourage people to take a precautionary approach to swimming or eating shellfish from this area," NPDC water and wastes manager Mark Hall said.

Asked why the project had to be undertaken in the height of summer, Mr Hall said there was no choice. Once the first aeration basin was cleaned out and upgraded, after a short period testing the results, the same thing would have to be done to the second basin.

"So we decided, at some stage we had to bite the bullet and do it," he said. "But summer is also the best time to do this sort of work, because summer low water flows mean there will be the least amount of effluent going into the sea."

The average sewage flow into the wastewater treatment plant is 400 litres a second, but when it is wet, that can increase considerably because of stormwater.

The shutdown is likely to be smelly as solid material at the bottom of the aeration basin is dug up and removed.

"There is 20 years of accumulation in those basins.

"Whether there is any odour will depend on the weather conditions and air temperature, how long the job takes, and the amount of material we have to remove. We apologise in advance if there is any odour," he said.

Mr Hall said when the aeration basin emptied, it would have its concrete structure modified, and have pipework and 2500 diffusers installed.

Taranaki Daily News