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Flash flooding in Plimmerton leaves 15 homes uninhabitable

flooding in Plimmerton
Flooding in Plimmerton. Photo from RNZ by Jane Mather

Report from RNZ
At least 15 homes are uninhabitable and some cars have been written off after flash flooding this morning in Plimmerton. Torrential rain about 10am sent water rushing through the homes.

Plimmerton fire chief Carl Mills said there was nothing crews with pumps could do to hold back the water, which was made worse due to high tide at the same time.

“With the extra rain that came it really got too high, and went into people’s main living spaces. In one place if you’re in the driveway I think the water was a couple of metres deep, and probably half a metre deep in the homes in some cases.”

flooding in Plimmerton Karehana Park
Flooding in Karehana Park. Photo from RNZ by Stasia Jackson

Firefighters visited about 65 properties in Plimmerton’s Karehana Bay, which bore the brunt of the flooding, and Fire and Emergency NZ took 24 111 calls connected to the deluge.

Mills said residents were recovering any salvageable belongings and clearing silt and debris from inside houses and yards.

The Plimmerton fire station is open to any residents forced to leave their homes.

Roads and properties in Titahi Bay were also flooded. The Titahi Bay Fire Brigade posted a warning online asking for people to take care of hidden dangers under the water.

“We’ve been out all morning in the wet assisting some families with flood damage and pumping water away from their homes. Please take care around flooded areas with contaminants, open hidden drains etc.”

With more rain coming, the brigade asked residents to check that drains around their home are not blocked, so water can drain.

A Dimock Street resident said she was sick of the repeated flooding problems in her street. “There’s flooded homes, heaps of mess on the street, rubbish and sludge to clean up now. My neighbours had cars lost in the floods over the years, including today … it’s half under the brown water. The flooding has been recurring in our street for years and it gets worse each time. Porirua homeowners pay amongst the highest rates in New Zealand and the Porirua City Council do nothing to improve the situation. Rents in Porirua are the highest in New Zealand – so unfair!”

Mana Archery Club was holding a coaching course at their club in Plimmerton Domain this morning when the rain started, and many members found themselves trapped.

Club committee member Matt Kelland said when they started the course at 9am it was raining. “I was just really surprised it all happened so quick. We came out at about 11am for break and pretty much the whole green and most of the area was under water, we didn’t notice until we came out. By midday the bowling green started to fill up with water, and after 15 minutes it was completely full.”

He said they became worried the club rooms would flood, so members quickly lifted everything they could off the floor. The car park had flooded, which meant those in the domain couldn’t get out.

“A couple of people got out in their 4WD got out earlier when it wasn’t quite as high, but the rest of us can’t get out because the cars are too low,” Kelland said.

The rain caused major traffic delays and road closures this morning. The Plimmerton roundabout on State Highway One was closed due to flooding, and the road from there to Paekākāriki was also shut down. But by 2pm the Transport Agency said both lanes had reopened on the main highway, though Grays Road and the Paekākāriki Hill Road remain closed. Traffic was heavily backed up backed up.

A Porirua engineer said the SH1 Plimmerton roundabout has had flooding problems for many years, but over recent years the rainfalls have been heavier and caused more problems. Drainage works were needed to fix the issue, which would cause ongoing problems for SH1 otherwise, he said.

The Transport Agency was not able to answer questions about past flooding or plans for drainage work at the roundabout. Its Wellington Regional Transport Systems Manager Mark Owen said today’s flooding was a unique weather event, and it works closely with local councils and Wellington Water to ensure drainage on the highways works effectively. He said the agency “will work with our partners to assess whether there is anything we can do to minimise the impact of such events in the future.”

Wellington Water has had emergency service crews working in Plimmerton clearing culverts and flushing pipes. Staff from the service are working with the Porirua City Council to find emergency accommodation for families affected by the flooding.

7 comments:

  1. Dianne Mather, 29. November 2020, 19:11

    Devastating. How many “once in a hundred years” floods does Porirua have to have before the council gets this sorted out? [via twitter]

     
  2. Hel, 29. November 2020, 19:33

    Who would have thought clearing culverts would help drainage. Wellington Water and Porirua Council need to take a real good look at themselves.

     
  3. IanS, 30. November 2020, 8:16

    This may mean that the stream in the Karehana valley should be “daylighted” again, removing the culverts, even if it means purchasing a house or two at lower end of the stream across the road from the bay. Cultivating stream channels and designing streets as “deluge paths” to shift downpours directly to the sea is the common-sense change needed. Children’s play areas can be crafted at low areas to be considered as flood basins: they are cheap to clean out afterwards. Maybe the upper valley stream and park needs to be “re-wilded” and returned to more natural format to hold back run-off.

     
  4. Toni, 30. November 2020, 9:54

    Where’s the council’s accountability in this disaster? And what happens to householders’ future insurance for their homes? Is repeated flooding going to raise premiums, and reduce the value of their homes?

     
  5. Concerned Wellingtonian, 30. November 2020, 12:29

    Q, Is repeated flooding going to raise premiums, and reduce the value of the homes?
    A. Yes.

     
  6. greenwelly, 30. November 2020, 14:26

    Karehana Park is a natural low point for all the storm water in the valley. When it floods it simply inundates houses that back on to it. All the house/road stormwater pipes converge on the open culverted stream which then meets Airlie at number 22 and enters a 1.5 metre trunk main … It’s this pipe down Airlie road that was simply over loaded and could not cope. There are probably 3 options to stop it happening again :

    1) Lower a chunk of Karehana Park by a meter or two to allow additional ponding capacity without inundating the surrounding houses,
    2) Dig an additional trunk main down the bottom half or Airlie Road to the ocean,
    3) install another separate outlet from the park to the ocean, (Cluny Rd would probably be the easiest public path, or requiring a house or two would be shorter, but much more expensive.)

     
  7. Guy M, 1. December 2020, 8:28

    greenwelly – “Karehana Park is a natural low point for all the storm water” – well, sort of, but the real low point is the ocean. Digging out a hole in Karehana Park would have lasted about ten minutes in that rain storm before it filled up again. As can be seen from footage of people’s driveways, there was a mass of rock and silt that comes down in rain events like that. Probably the real blame has to go on whoever let those houses get built on a flood plain like that in the first place. That would be the Porirua City Council, presumably.

    But this is just a precursor to the catastrophe waiting to happen if the Council permits the land at Plimmerton Farm to get built on. Over there, just one valley over, a much bigger water catchment lies: the Taupo wetlands. Already the land near the base of the Taupo gets overloaded when it rains, and so James Street gets flooded for the 3rd time in 5 years. Again: the fault is the Council’s (and NZTA’s) for allowing buildings (and roads) to be built in the way of a natural floodplain. The proposal for yet more buildings in the direct line of this Taupo flood plane, and the proposal for several thousand additional new homes causing increased run-off from the hills in the water-catchment, will increase the occurrence of flooding catastrophes in the mouth of the flow. This is a really good example for the Council as to why it simply should not permit the Plimmerton Farm proposal to go ahead.