Less than expected: sewage emptied into Owhiro Bay from leaking wastewater main

News from WCC
Work to repair the leaking wastewater main at Owhiro Bay began around 1am on Friday morning. The pipe was reconnected by Friday afternoon, and the discharge to coast stopped at about 2.30pm. By Saturday the water was clear, and preliminary results show water quality quickly returning to normal.

In the end an estimated 500-600 cubic metres was discharged to sea. This is a lot less than the 2,000 or so that we were originally looking at, and was achieved through a non-stop chain of sucker trucks transferring wastewater from near the discharge point, to the network on the Kilbirnie side.

Wellington Water was also able to install a valve in the new section, which should improve our ability to manage future maintenance.

The rāhui will remain in place until further notice – likely the middle of the week, depending on water testing results.

Wellington.Scoop – August 4
Wellington Water has today failed to provide any new information on its emergency at Owhiro Bay. Yesterday afternoon it said there was a leak in a wastewater pipe at Owhiro Bay, and because of this it would be allowing 1000m3 of sewage to flow into the bay.

News from Wellington Water – August 3
Last week, a fitting on the main wastewater pipe serving Brooklyn and Island Bay suburbs developed a leak in a chamber at Owhiro Bay. Since then we have been exploring any possible options to fix this pipe with minimal impact on the environment.

We realise now that we’ll need to divert approximately 1000m3 of wastewater through an overflow pipe into the sea so that we can get in to repair the damaged pipe. Tonight from midnight, we will be using sump trucks to remove as much of the wastewater as possible, however the total volume is greater than our ability to store or divert all of it.

Health warning signs are in place, and water quality will be monitored both before and after the repair is made until the water samples return with normal levels. A rahui will also be placed over the affected coastal area. This forbids mana whenua entering the water until it is lifted.

We apologise for any disturbance in the area overnight tonight as we perform this urgent repair. We need to complete the work as quickly as possible to ensure the health and safety of all. We will be updating our website as the situation develops.

And on the Lyall Bay Facebook page – more information from Wellington Water

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.

And from the Wellington Water website:
Wastewater and sewage are the same thing – dirty water from homes and businesses that is sent to a wastewater treatment plant for treatment. It’s a mixture of water and human waste.

 

4 comments:

  1. Troy H, 4. August 2017, 7:48

    That sounds terrible and it took Wellington Water a week to make a decision to flood the ocean with shit. What are their emergency plans for an emergency break in pipes? Wait a week (do nothing) put all the sewerage in the sea, get a Maori area restriction for the contamination and call it a “min impact on the environment”.

     
  2. Dr Sea, 4. August 2017, 11:44

    I think this is outrageous. Our Council is so busy giving away public land to developers, it forgets its core business it seems…[via twitter]

     
  3. Troy H, 4. August 2017, 12:15

    Wellington Water’s website is wrong. Swimming in an ocean of shit and piss is not the ” same thing” as swimming in stormwater overflow.
    The Council contracts “United Water International” to operate Wellington’s three treatment plant$. The WCC focus on core services seems to be elsewhere. There are heaps of resources, time and energy at the WCC for poisoning, trapping, torturing and killing animals but when it comes to core services its private company just spins while the rates keep going up.

     
  4. CC, 4. August 2017, 17:53

    For heaven’s sake Troy, the council resources for pest eradication and environmental maintenance and regenerative planting are minuscule and do less to detract from the work of Wellington Water than the massive subsidies and freebies that go the way of developers, so called entrepreneurs and bribes, like that given to Singapore Airlines. None of it would happen without the massive effort of volunteers. If you have concerns about the way that predator control is carried out – please do the job yourself in a humane manner rather than emotively ranting. Some of us are sick and tired of seeing the torturing and killing of endemic species, some of which are heading the way of the Dodo.

     

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