A repair by Wellington Water is going to send around 1,000,000 litres of waste into the sea near Owhiro Bay.
In a post by Wellington Water, read below:
“You might have heard about our need to make an emergency repair to a pressurised wastewater main, and that this will mean a discharge of wastewater to the sea. Quite a few people are quite energised by this event – quite rightly so – and are wondering how it could happen.
Discharging to sea is not something we want to do either. Usually when we carry out emergency repairs on the wastewater network, we’re able to manage the interruption in service by temporary storage, diverting the flow, or using sucker trucks.
But the pipe is a big one, and it’s long. It carries wastewater from Brooklyn all the way up to a tunnel that passes beneath Mount Albert, on its way to the treatment plant at Moa Point.
In this case, despite all our normal methods and a few others, the volume involved is too much to manage. We’ve managed to reduce what we think will discharge to around 1,000 cubic metres of water. The alternative would be for this to overflow onto the street – but that would end up going down the stormwater system and out to sea anyway.
How can this happen? To avoid any kind of overflow in a wastewater network, you’d need to have a failsafe system, or duplicate pipes. That’s not practical. The cost to duplicate all the trunk wastewater mains in the city would be in the 10s if not 100s of millions of dollars. Wastewater network overflows happen in every city. The best thing you can do is design for them – to control where the water goes, and so minimise the risk to human and environmental health and safety. That said, we do need to make sure we’re on top of our proactive maintenance.
A few other things to note. This is not an ongoing situation – it’s a one off emergency. Advice we’ve received is that the wastewater will clear quickly once it reaches the ocean, and there will be no lasting impact.
We’re also really grateful we’ve had enough time to work with our iwi partners to perform a rāhui, and with health and environmental authorities to get their advice. Kura Moeahu led the laying of the rāhui at Owhiro Bay which will extend from Lyall Bay to Tapu Te Ranga. Kura was assisted by Alishia Moeahu, Pekaira Rei, Kurt Komene and accompanied by other members of Taranaki Whanui and Wellington Water staff, including the Acting CEO Audrey Scheurich and GM Gary O’Meara.
We’ve contacted residents living directly opposite the chamber where the leak is, who will be most affected by the work. We haven’t been able to directly contact all residents who will be affected by the discharge – we know that will be thousands of people. But we hope they’ll understand the need to carry out the work as quickly as possible.
Best wishes to the crew working on the repair. They know how important it is to get this done safely, quickly, and to get it done right.”