Albatross Close updates

We'll keep you informed of the road's status and remedial and investigative works being done.


We are continuing to work to resolve the road surface issues at the northern end of Albatross Close. The safety of residents and maintaining access remain our key priorities.  We’ve been monitoring the situation throughout and taking action to respond to and fix it.

19 October – update

We are pleased to advise that the successful tenderer for the remediation work on Albatross Close is Juno Civil Ltd, who have operated in the Wellington region for the past 40 years. They have vast experience with the construction of retaining wallssimilar in size and type to what is planned.  Porirua City has met with representatives from the company and are finalising the timetable of work and contract requirements before work. Juno Civil expect to be setting up on site towards the end of October and Griffiths Drilling will be on site soon drilling a couple of test boreholes for the piles. The drilling and install of the piles has been sub-contracted to Richardson Drilling 

Juno Civil are incorporating into their plans the need to keep open the footpath access to Albatross Close from James Cook Drive during the remediation work, with the works scheduled to be completed and road re-opened by the end of March 2019.

The temporary road has been sealed today and with the line marking and signage due to be completed over the weekend, we expect both lanes to be open on Tuesday next week. At this time the traffic lights will be removed.

27 September – temporary road update

To assist with traffic flows on the temporary road, we have decided to widen the entire road from the top by the traffic lights down to the car park entrance. This work has commenced and we expect it to take up to two weeks, weather permitting.


Once the work is completed and both lanes are in use, we will remove the traffic lights and make a slight change to the exit out of the car park when coming down from Samwell Drive. Thank you for your continued patience while we carry out this work. 

19 September

Work to repair the slip at Albatross Close has been continuing, with five subsoil drains installed in recent weeks to help with water removal. These drains were installed as part of a planned programme of work to channel water that was discovered to be flowing under the road. 

There has been significant subsidence in the road since the November 2016 earthquakes and flooding, with most of the movement occurring over the wetter winter months this year.

Following initial movement in the road, we drilled boreholes and installed inclinometers last October to pinpoint the location and depth of the subsidence. We then had a very dry summer, so no movement was detected until mid-June this year.

A number of initial design solutions were put forward for fixing the road, but waiting until there was more information about the source and depth of the slip has meant that a more informed, robust and long-term solution could be drawn up.

We’re going to be building a palisade wall or a series of 23-metre-deep concrete reinforced piles that will form a 60–70 metre long retaining wall at the top of the bank. We’ll also be installing a further 16 subsoil drains while the wall is being built.

In the interim, to improve traffic management, we’re widening the temporary road to the corner, so it can take two lanes of traffic from the top of Samwell Drive. We’re also removing the traffic lights, and installing line markings and give-way signage, as there’s line of sight from the corner to the car park entry, which will remain a single lane.

Tenders for building the Palisade wall close at the end of this month (September). Once the tenders have been assessed and a contractor has been appointed, we’ll be able to determine the timeline for consenting, construction and completion. 

31 August 2018

Football tournament

Wests Football Club have their annual children’s football tournament this weekend at Endeavour Park, which will attracts a large number of players and spectators.

Given the large volume of vehicles expected on the temporary road, we have put in place a comprehensive traffic management plan for the weekend, with staff from our contractor ATMS onsite to manage the traffic volumes and parking.

The plan includes restricted parking on Albatross Close, Seagull Place and Samwell Drive (in the immediate area of the intersection with the temporary road). ATMS staff will also operate stop/go at the top and bottom of the temporary road, and control pedestrians at the crossing from the clubrooms to the field during the event hours

They  will also have a staff in the immediate area to ensure cars are parked legally.

Temporary road changes

Following feedback, we will be making some changes to the temporary road today. We have widened the top of the road at the Samwell Drive end, so the existing traffic lights on Samwell Drive can be moved approximately 50 metres down the temporary road. This will enable people to turn from Samwell Drive in either direction and wait for the lights on the temporary road. When coming up the temporary road, people will also be able to turn left or right at the Samwell Drive intersection, as the cones on the road will be removed. New road markings will be put in place.


30 August 2018

People and houses

The results of the monitoring of nearby houses undertaken last Friday showed no or slight movement at the various locations, based on the baseline results taken on the 26 July. These are accurate to +/-1mm. This monitoring survey covers the footpath, front gardens/ walkways and house foundations, so we can compare this to the baseline set about five weeks ago.

We’ve installed a temporary road and installed traffic lights to help manage the traffic and ensure that residents have access to their properties. The Council has been in regular contact with directly affected residents about what’s happening via email, letters, a page on our website, phone calls and meetings. 

Cause

The slip has been caused by an underground water source that has changed course, so it has been difficult to pinpoint the cause of the subsidence.

While there was some small movement in the road prior to the November 2016 earthquakes, we saw some larger changes immediately after that, and there has been ongoing movement, especially after heavy rainfall. The drop is now 1.6 metres.

Our geotechnical engineers, ENGEO, say the current movement is not unexpected and is part of the slumping process.

Monitoring
Last October we drilled boreholes and installed inclinometers to measure road and land movement and gather more information.

Until mid-June, there was little or no movement (mostly due to a very dry summer). But there have been several large road movements since then due to rain, including a dramatic slump as recently as last week.

Solution

We’ve looked at a number of options for fixing the road.

We have opted to build a palisade wall – or a series of 23-metre-deep concrete reinforced piles that will form a 60-70 metre long retaining wall from the top of the bank.

The road has slumped further last week because of the wet weather.

Given this movement, we will be installing five of the planned 21 subsoil drainage within the next week, with the balance installed when the wall is built.

We have the design for the palisade wall and went out for tender on Thursday 30 August. Once the tenders are in and we have determined who the contractor is, we’ll be able to give some timeframes for critical parts of the work, and the reopening of the road.

 Cost

The palisade wall had initial estimated cost of $1.5 million. Some of this will be funded by NZTA.

History

There was subsidence of the road at 4–6 Albatross Close in October 2016. Some sub-soil drainage was installed and the road was repaired and resealed.

There was a second incidence of subsidence in March 2017, probably related to the November 2016 earthquake. A temporary repair was completed by mid-2017, consisting of remediation and resealing of the road, installation of additional field drainage at 3m depth (the assumed slip plane at the time). Some monitoring equipment was installed at the same time as the repair.

In June 2018 some cracks appeared and, after a period of heavy rain, there was significant subsidence on the road, which has continued.


10 August 2018

The design of the palisade wall is well advanced and we are on target to go to tender this month. Once the tenders are in and we have determined who the contractor is, we’ll be able to give some timeframes for critical parts of the work, and the reopening of the road.

The walkway at the bottom of Albatross Close that runs parallel to Endeavour Park will remain closed at least until the road is re-opened. We are aware that we need to keep the footpath to and from James Cook Drive open as much as possible, but we will be better able to assess the access options once we’ve confirmed the construction methodology for the remediation works.

We’ve made some layout changes to the entry/exit lanes in the car park and are widening the top of the temporary road at the Samwell Drive end. We are going to move the lights currently on Samwell Drive approximately 40 meters down the temporary road on the widened area, and hold traffic there rather than on Samwell Drive. The cones will then be removed on Samwell Drive to enable traffic to turn both left and right on entry and exit from the temporary road. Once this new area has been chip-sealed, we will make these changes. We are also taking the opportunity to reseal the temporary road at the same time.

We are working with the Western Suburbs Football Club on a comprehensive Traffic Management Plan for their annual tournament, which takes place on the 1 and 2 September. To ensure the weekend runs smoothly a traffic management crew  will be on site at critical times during the weekend to manage the traffic flows and parking

6 July 2018

The Council has agreed to fund slip repairs for Albatross Close. 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.

The slip has been caused by an underground water source that has changed course, so it has been difficult to pinpoint the cause of the subsidence. It has affected the road, residents, a preschool and a football club and requires a substantial, robust and long-term solution.

The Council has opted to go with building a palisade wall – installing a series of 25 metre deep concrete reinforced piles to form a 60-70 metre long 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. The bank will also be planted with deep-rooted, water-hungry trees, which will further improve the stability. The road will then be resurfaced.

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.

21 June 2018

Recent land movement

Last October we installed inclinometers to measure road and land movement and gather more information. Until Thursday last week, there had been little or no movement, but some cracks appeared in the chip seal in the area of the road that moved last year, and further movement occurred over the weekend and this week.  While we know that the road may continue to move, we are confident that there is no imminent danger to residents. 

Investigation works

Works at the northern end of Albatross Close last year were part of the investigations to resolve the road surface issues. Those works included drilling boreholes, reinstating and resealing the road, and installing water level monitoring equipment, six sub-soil drains and five inclinometers to measure movement. 

We have been collecting data from these investigative tools and are continuing to monitor the situation, especially after heavy rain events. Recent movement in the land has allowed us to collect more data about the land and geotechnical engineers will use this information to design potential solutions. There is a lot of new data to be reviewed and it will be used to designed and implement an appropriate solution. 

Road closure and temporary road reopening

To reduce pressure on the road and lessen potential impact on vehicles, we have closed the northern end of Albatross Close and re-opened the temporary road. We will post an item on our Facebook page and on the Whitby community page. 

Albatross Close temporary road route

The temporary road is likely to remain open for a lengthy period while permanent repairs are undertaken to the affected section of Albatross Close. Once we have more details on timeframes we will make these available.

Emergency vehicle access

We will inform all emergency organisations about the upcoming closure of the northern end of Albatross Close and the alternative access arrangements, and will keep them informed about any further restrictions.

We are committed to a long-term solution at Albatross Close. We thank you for your continued patience while we work to resolve the issues in a timely and cost-effective manner.   

18 May 2018

We have prepared an FAQ sheet sent to property owners at 2-8 Albatross Close.

20 April 2018

Continuing investigations and monitoring

Monitoring activities continue.  This includes visits to site and reviewing data provided by the inclinometers. 

The outcome of the analysis data  to date is: 

  • there has been no significant movement in the inclinometers
  • there is waterflow in the northern most drain although again not significant.

The next steps are to continue to monitor, collect and analyse data while considering some long-term options.

Inclinometers

The main purpose of the inclinometers is to detect zones of movement below the ground surface. Where there is movement, the inclinometers will help us determine how the ground is moving and whether the movement is constant or accelerating.  The more we understand about the ground movement, the more informed and effective our design for work will be.

There has been minimal movement since we installed the inclinometers and other monitoring equipment. This is not unexpected given the relatively dry summer we have experienced.  

We'll continue to monitor and collect data on a regular basis over the next period of time until we obtain sufficient data to progress to the design stage. This will include additional data collection and analysis after a rainfall event. 

Traffic restrictions

There are currently no traffic weight restrictions in place but the 30kph speed restriction area remains in place in the immediate vicinity of 4 and 6 Albatross Close. Speed cushions have been installed.


Borehole drilling rig

Borehole drilling rig in action, Albatross Close.

Alternative access road

We have closed the alternative access road in front of the football club. We will keep this as a back-up road should it be needed in the future, for instance when any permanent solution in Albatross Close is implemented. However, this alternative access road will be closed in the interim and not available to the public. Once the final solution has been implemented, this road will be permanently removed and the grass reinstated.

Whitby Walkway

The Whitby Walkway below Albatross Close is open.

Updates

If you would like to be kept informed on developments, please email slips@pcc.govt.nz.  Please include your name.