An incident that resulted in raw sewage being washed into the Mahurangi River earlier this month has been blamed on a blocked manhole.
Used condoms, excrement and toilet paper littered Elizabeth Street, near the bridge, on Saturday morning August 5. A Watercare spokesperson says the cause of the blockage was congealed fats, oils and grease, which had been poured down the sink by residents and businesses.
She says although the area was thoroughly cleaned and disinfected, the contractor did not carry out proper procedure.
“Some wastewater was washed from the ‘catch-pit’ into the river,” she says. “The contractor has been spoken to.”
The amount of waste that entered the environment in the hour between when Watercare was alerted to the issue and when the clean up crew arrived could not be quantified.
As a result of the incident, members of Watercare’s trade waste team visited Warkworth last week to check grease traps, and talk to local eateries and food premises about the dangers of pouring fat, grease and oil down the sink. They also distributed leaflets to raise awareness about how this practice impacts on the environment and how to dispose of fatty cooking liquids safely.
Watercare will undertake work to try to reduce overflows at the Elizabeth manhole, which will include a regular flushing programme.
“This isn’t just a Warkworth issue – it affects the whole of the Auckland region. Last year, 84 per cent of overflows during dry weather were caused by people flushing rubbish down the toilet, pouring cooking fat down the sink and tree roots that had grown into the pipes. Rags and wipes are some of the biggest issues. Most wastewater pipes are only 100 millimetres in diameter and are not designed to carry anything other than wastewater and biodegradable products, such as human waste and toilet paper.”
Meanwhile, work is currently taking place on a major wastewater upgrade to service the Warkworth, Snells Beach and Algies Bay areas. This includes a new wastewater treatment plant at Snells Beach, upgrade of the Warkworth Wastewater Treatment Plant, a pipeline consent to take the flows from Warkworth to the new plant at Snells Beach and four new pump stations along the route.
The project will cater for expected population growth in the region and allows for future expansion beyond 2050. When completed, the new wastewater treatment plant will end discharges into the Mahurangi Harbour.
“Wastewater will be treated to a very high quality using membrane technology and will be discharged from an ocean outfall 600 metres off the coast into the Hauraki Channel,” the Wastewater spokesperson says.