WestConnex tunnel depths: Report by Leichhardt Against WestConnex

Leichhardt Against WestConnex (LAW) has been analysing the tunnelling and construction works planned for WestConnex Stage 3 (the M4-M5 Link from Haberfield to St Peters). They recently published the following report, which includes an analysis of the impacts these works could have on homes and properties along the route. I've been getting a lot of queries from residents who are concerned about this, so I'm republishing it here with LAW's permission.

Tunnel depths

There has been a lot of press and speculation about the shallow tunnelling coming under our homes across Leichhardt, Annandale, Camperdown, St Peters, Newtown, Stanmore and Haberfield as part of the M4-M Link (Stage 3). Also several reports about property damage for Stages 1 and 2.

We are not interested in running a scare campaign so here are the facts as we know them:

  • There are reports of cracking in homes in North Strathfield and St Peters allegedly caused by WestConnex tunnelling. Some of these homes have tunnelling about 40 metres underneath. There are also complaints that damage is being denied in all cases by WestConnex contractors.
  • The current process is that the contractor undertakes an initial survey prior to works commencing and then a subsequent survey if they receive a complaint during or after construction. Proving causation is complex and the contractor interprets the report and decides if they have caused the damage. If they decide they haven't, there isn't much recourse for residents who may need to expend thousands of dollars trying to prove causation and it appears that data and reports from the contractor are not been made available to them.
  • The contractors dismiss, generally without any investigation, any reports of damage where the home is more than 50 metres from the tunnelling area (outside the zone of influence as determined by the contractor). The effects of water changes due to the tunnelling don't seem to form part of this analysis, the focus appears to be vibrations, based on what I have seen.
  • We understand that all claims for damages have been rejected so far.
  • RMS places sole responsibility on the contractors to deal with damage. If you complain you will be in a mediation (if they agree to have one) with the consortia's lawyers - despite this being a Government project.

What will happen for us in Stage 3

There has been one improvement:

  • An independent property assessment panel will be set up to assess damage. However RMS is selecting the members of the panel.

In addition, the issues about the complexity and cost in proving causation remain.

  • This change to assessment will only apply in the future, so those affected in stages 1 and 2 are stuck with the contractors assessing whether or not they caused the damage.
  • If you are outside the zone of influence of 50 metres even for Stage 3, you are unlikely to be afforded a survey from the contractor and it will be an uphill battle to prove that any damage is caused by the tunnelling. [Note from Pauline: properties that are within 50m of the tunnel route or surface construction can be seen on WestConnex's map of the proposed tunnel route. Eligible properties are marked with a grey box - click on these to see the address and the indicative tunnel depth at that point.]


  • The Government's own Environmental Impact Statement (EIS) states that tunneling at deeper than 30 metres can reduce the risk of subsidence. The average tunnel depth in the latest map is significantly shallower than that in the EIS which we object to are the EIS formed the basis of approval for the tunnel. The contractor has told us there will be subsidence, it cannot be avoided. The issue is how much and we just don't know. The average tunnel depth is 35 metres and 4,500 homes are in the impact zone. In parts of Stanmore it is as shallow as 12-14 metres. When the Rozelle tunnel route is disclosed, the depths are likely to be even shallower given the number of portals. This is even more worrying when the age of the homes in this historic quarter is considered.
  • The issue of sink holes isn't addressed at all in the EIS.
  • Stage 3 involves exactly the same techniques as the earlier stages; no additional mitigation is planned. However the tunnel for stage 3 is much wider - 8 metres wide! And generally shallower than the earlier stages. In addition, the tunnel is under many older areas with older homes arguably less likely to cope with subsidence and increasingly dry soil conditions. Stage 3 is also the most technically difficult part of the tunnel. The Rozelle interchange, a different project with a different contractor, but linked, involves 3 levels of tunnels, a first anywhere in Australia, possibly the world.
  • Leichhardt and Annandale faces extensive tunnelling. We are the only area that will have tunnelling from the Rozelle interchange (different contractor) and the mainline tunnel. We also have a massive underground sub-interchange near the lLlyfield light rail area, it is huge and largely unreported in the media.
  • If you live with sandstone underneath your home you are less likely to suffer damage. The contractors have told us they will be 'chasing the sandstone'. So don't assume the current route is the final route, it will change as tunnelling progresses. The contractors have told us there is good sandstone in much of Stage 3 and we have asked for a map depicting this. But areas with shale and soil, such as near the St Peters and Haberfield portals, are at greater risk.
  • In the EIS for stage 3 the Government said it will fix any damage it causes. This isn't much comfort when the experience of the current residents is considered and we are yet to be convinced that the property panel will result in a fairer outcome.
  • There is also no guarantee that some homes will not continue to hear and feel the vibrations of traffic under their homes once the tunnel opens.
  • The notation of a tunnel underneath your home will be added and you will receive no compensation for the compulsory acquisition of the substratum. There are no appeal rights by law with respect to this process.


  1. Get an independent property dilapidation report for your house done. Contact the Inner West council about what they are planning with respect to free survey reports (see Council's website for more information and contact details).
  2. Take photos of your house, inside and out. Take them every few months.
  3. Sign petitions, post on social media - get the message out there to the Government that we will not sit back and allow our homes to be damaged.
  4. Talk to your neighbours and friends - get the information out there. You will be amazed that, despite efforts of groups such as ours, many people still don't know what is planned or what is going on.
  5. If you experience damage, which you think may be caused or contributed to by WC tunnelling, contact the WestConnex Action Group who are maintaining a register so we can know the extent of damage allegedly resulting from this project and potentially plan for future group legal action. Visit the WAG website Damage Register for more information.
    6. Jamie Parker and Jenny Leong have information sessions on the tunnelling coming up - we will post details.

What will LAW do?

  • We will continue to push for deeper tunnelling.
  • We will continue to argue that the project should not be approved with shallower depths than disclosed in the EIS.
  • We will place pressure on the contractors to provide data and reports to residents so that we are informed about the risks.
  • We will continue to expose this shambolic project for what it is - massive vandalism and recklessness.
  • We won't allow our community be continue to be collateral damage for this utterly disastrous project.
  • We will continue to oppose this project, not just because of the potential impacts to our houses but because it is an ill-thought out scheme that will tie us to car dependency and divert funds needed for public transport which is the true solution for congestion and one that supports climate change action.
  • We will continue to represent Leichhardt on the Community Reference Group, attending both meetings for the mainline tunnel (with the contractors in attendance) as well as the second committee set up for the Rozelle interchange.
  • We will make sure the contractors and RMS are aware of our concerns and we will hold them accountable.

Questions? Comments? Get in touch with Pauline here.

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