Sunday, February 25, 2024

Update on storm-hit water and wastewater services

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Lower Nihotupu Dam after Friday’s storm. Photos Watercare

Watercare has made steady progress restoring water and wastewater services in the wake of Friday’s storm, but is warning customers to prepare for further disruption with the heavy rain expected tonight and tomorrow.

Watercare chief operations officer Mark Bourne says the company has had teams working around the clock to find, investigate and repair problems affecting parts of the water and wastewater networks.

“After Friday’s storm there were about 3000 properties without water. Our staff and contractors have been working flat tack to find and repair broken pipes and restore service, and we now believe all customers should have water on.

Watercare environmental assets manager James Talbot surveys the impact at Lower Nihotupu Dam.

“However we’re encouraging customers living in the wider Titirangi area to be prepared for intermittent water supply issues over the coming days, as we expect to find more damage to our networks caused by slips, and more rain could exacerbate the situation.

“Ten of our wastewater pump stations were severely flooded in the storm, damaging their electrics. We managed to get six operational over the weekend and have this morning returned another two to service. We expect to get the other two back in service this evening.

“With more intense rain on the way though, we’re not out of the woods yet. We’ve been busy sandbagging some of our pump stations and sourcing back-up generators in case we need them tonight.

“One of the challenges we’re facing is the quality of the raw water in our western dams. In a normal January week, we’d expect about 23mm of rainfall in our Upper Nihotupu catchment, but in the last week we’ve had 370mm.

A huge landslip in the Waitakere water catchment after Friday’s storm.

“The intense rain has caused significant landslips that have sent a huge amount of dirt into the dams, which makes it far more difficult to treat. We’ve taken two of these western dams out of service until the water quality improves, and have reduced production at our Huia Water Treatment Plant.

“Yesterday our dams team released some of the dirtiest water using the ‘free discharge valves’ at the bottom of Lower Nihotupu and Lower Huia dams to try to reduce turbidity. While this has got rid of some of the dirtiest water, dirt is still constantly being washed into these lakes.

“Our Ardmore and Waikato water treatment plants are coping well and we can produce enough water for Auckland if the Huia plant shuts down – so long as people use it wisely.

“We’re fortunate in Auckland to have a highly-connected water network, which means we can get water all around the city. But if Our Huia Water Treatment Plant shuts down, we have to get water from our southern plants all the way up to the northern reaches of the city. For us to do that successfully, we’ll need people to be mindful of their water use.”

The Lower Nihotupu Dam spillway.

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