The Council has agreed to fund slip repairs for Albatross Close.
Porirua
Mayor Mike Tana says the Council has agreed to fund slip repairs for Albatross
Close.
“It is our responsibility – we must fix it, and fix it well,” says Mayor Tana.
The
proposed solution is estimated to cost $1.5 million. Of this, $220,000 will be
funded by ratepayers, with the balance coming from an NZTA subsidy and savings
from other slip work.
“This
is a major slip, caused by an underground water source that has changed course,
so it has been difficult to pinpoint the cause of the subsidence. This has
affected the road, residents, a preschool and a football club. It requires a
substantial, robust and long-term solution,” says Mayor Tana.
“The
Council has opted to go with building a palisade wall – installing a series of
25 metre deep concrete reinforced piles to form a retaining wall from the top
of the bank. Drainage will be installed in the slip area and the damaged water,
stormwater and wastewater infrastructure will be replaced. We will also plant
the bank with deep-rooted, water-hungry trees, which will further improve the
stability. The road will then be resurfaced,” he says.
Northern
Ward Councillor Anita Baker is pleased that the Council has uncovered the
source of the problem and has found a robust solution. “It has been unsettling
for residents and I’m relieved that we are able to fix the problem. The whole
process expected to take 4–6 months.”
The
Council’s geotechnical engineers, ENGEO, are working on a design for the
palisade wall, based on the latest information available from onsite monitoring
equipment.
Background
The stretch of Albatross Close, a cul-de-sac of 76 houses near Endeavour Park in Whitby, has had a history of subsidence, which was first noticed in 2011. There was a major subsidence of the road in front of 4–6 Albatross Close in October 2016, due to high groundwater levels from an unknown source.
After
the November 2016 earthquakes, the same section of road subsided. A temporary
repair was completed in late 2017, which consisted of adding field drainage at
3 metres deep, remediating and resealing the road, and adding inclinometers to
monitor movement.
In
June 2018, some cracks appeared at the top of the bank after a period of heavy
rain which led to further slumping. The road was closed and the temporary
road (which was installed after the 2016 earthquake event) was reopened to give
residents of Albatross Close and Seagull Place access to their properties. The
water main recently burst and has been temporarily replaced above the ground,
with temporary repairs currently underway to both the wastewater and stormwater
mains.
6 Jul 2018
