Residents of sinking Porirua street unsure 'how long we have to go through this'

It could be another seven months before frustrated Porirua residents can drive through the main entrance to their street.

In the last two months, the northern part of Albatross Close has sunk by a metre, with a total drop of 1.6 metres since June.

While it looks like the aftermath of an earthquake, or a cake that hasn't risen, it's a change of direction in underground water that's caused the drop.

Residents of Albatross Close still need a solution to the problem. Source: 1 NEWS

"The situation's certainly got worse in the last few weeks, we've seen the deterioration," Porirua City Council transport manager Mike Evans told 1 NEWS.

The main entrance to the Whitby street was closed in June when cracks appeared at the top of a bank next to the road, which has slumped.

Since then the water main has burst and has been temporarily replaced above the ground.

This follows the first major drop and repair in October 2016 and the second slump in March 2017, which is believed to be linked to seismic activity from the Kaikoura earthquake.

A temporary repair was put in place, along with monitoring equipment.

"The typography in Porirua is vulnerable to slips, there certainly have been a lot more slips with the recent flooding events," Mr Evans said.

He said the road was made with average material from a nearby hill in the late 1970's, but the slip source has been confirmed as deeper so the cause is water movement.

Some residents say the removal of old trees is behind the sinking road.

Mr Evans said the council has assessed this as having a minor impact.

He said the council is now investigating what other suburbs could be vulnerable to slippage.

Residents with driveways that are directly next to the slip cannot drive into their garages.

Resident Marina Wall said her family is trying to stay optimistic about the situation but some residents are frustrated by the situation.

"Of course no one wants to be inconvenienced by something like this, especially with the amount of times that we have to travel in and out of our house so it has caused a lot of extra kilometres on our car, an extra petrol use.

"We're still quite uncertain how long we have to go through this," Ms Wall said.

Designing a solution for a changing situation has been challenging, but the council’s Mike Evans says it’s now ready for the design to be put out for contractors to apply to fix the road.

"We’re going to build a 70 metre palisade wall, which is a series of 23 metre deep reinforced concrete piles… and will basically hold the road and link into the bank to some extent," he said.

The bank will be planted with deep-rooted trees in the hopes this will provide further stability.

The work is expected to be completed by mid-January to mid-March next year.

The council's built a temporary road through a sports field at the end of the street so residents can still use their cars and park nearby.

But some residents say there are safety issues with the temporary road.

"There are some times when the lights are working and you don't know whether to go or stay," Marina Wall said about the traffic management for the temporary road.

"We obviously all have to take great care because some of the  three lanes of through traffic through the car park do sometimes travel at speed," Nicola Dickey, head teacher at Mana Montessori Preschool said.

Ms Dickey said parents of children who attend the preschool have accepted that the sinking road can't be helped.

"I think everyone's a bit shocked when you see it but we know that what’s being done is being done as fast as it can," she said.

Finding a solution to the Albatross Close problem has been complicated. Source: 1 NEWS