The Edgecumbe oxidation ponds have recently undergone costly work to remove a significant amount of debris, which has been affecting the natural processes of the ponds. Most of the debris is a result of residents flushing unflushable materials down toilets and drains. Whakatāne District Council Acting General Manager Infrastructure, David Bewley, says this work alone has cost in the vicinity of $14,000 and will continue to cost ratepayers if people continue to flush things they shouldn’t.
“Contractors removed five tanker loads of matted waste, mostly wet wipes,” he says. “I know many wet wipe brands are marketed as flushable or biodegradable, but they don’t break down like toilet paper does. Although they appear to be made of cotton, most wipes consist of polyproplyne or polyester – and therefore, stick around for a very long time.”
Council staff who monitor the ponds estimate the build up of wipes took about two months to accumulate, with recent winds causing the waste to cluster at one end of the pool. According to those who removed the debris, what could be seen on the surface was only a small percentage of the matter underneath. In other oxidation ponds, non-flushable items such as wet wipes, sanitary products, condoms, rags and paper towels can be screened from the liquid and sent to landfill, which is where they should go in the first place. There is no screening system in the Edgecumbe ponds, which is why the materials caused an imbalance in the natural treatment process.
“Normally, sewage is pumped into the ponds and sunlight and algae kill the harmful bacteria and viruses without the need for extra chemicals,” Mr Bewley explains. “Unfortunately, wet wipes and other materials float on the top of the pond and prevent sunlight from performing its important photosynthesis role. This affects the entire system, which is supposed to be a cost-effective and fairly low-maintenance way to treat sewage.”
Mr Bewley also encourages people to think about how they dispose of fat, grease and oil – which cool and turn hard when poured down the sink. The hardened fat and oil then joins other non-flushable things like wet wipes to make huge fatbergs. These fatbergs clog up pipes and can cause expensive issues in both household and Council pipes.
“I know it may seem like only a little bit of fat, or only a couple of wipes, but please remember that if everyone does it, the cumulative effect is massive,” he says. “I know other Councils that have had to deal with 15 metre-long fatbergs in their wastewater pipes, which is an extremely pricey task that ratepayers ultimately end up paying for.”
He says the correct way to dispose of leftover fats and oils is to pour them into a container before putting it in the rubbish bin, and to wipe greasy pans with paper towels before washing the dishes. Non-flushable items are exactly that – non-flushable, and should be put in the rubbish bin rather than down the toilet.
“Remember the three Ps – only flush [toilet] paper, pee or poo. Nothing else.” says Mr Bewley.
Council water services staff have taken various groups, including schools and service organisations such as Probus, for tours of the sewage treatment plants in an attempt to highlight the non-flushables issue. Mr Bewley encourages any other interested groups to contact the Council to arrange a tour.