March 9th saw another incidence of subsidence at the M6 Stage 1 project in Sydney, following an earlier sinkhole reported to be some 10m wide and 150m away, which opened up on March 1st resulting in the evacuation of 20 workers.
Transport for NSW (New South Wales) said in a statement, “The location is within a contained construction area not accessible to the public and the site is not located near any residential or commercial properties.
No injuries occurred, and a small work crew who were in the tunnel at the time, were evacuated as part of standard safety procedures.
This incident occurred during excavation of the face of the south-bound tunnel, about 12m from the surface, on the airport side of West Botany Street.
Safework NSW was immediately notified, and an exclusion zone has been established around a 20 square metre area, while detailed geotechnical and engineering assessments are undertaken.
Initial remediation work which will include securing the area has commenced.”
As an extra precaution, contractor Joint Venture CGU has halted all further tunnelling work in the impacted area while engineers and geotechnical experts assess further.
No other sites across the M6 Stage 1 project have been impacted although any potential changes to construction timelines are unknown at this stage. Just 150m of tunnelling is left on M6 Stage 1 to completion.
Most tenants affected by the earlier March 1 subsidence, which occurred on the other side of West Botany Street, approximately 150m away in an industrial estate, have been able to access their facilities since Friday.
A spokesman for JV member CPB Contractors said, “They are not connected, they are two completely different types of Geotech, they are two sperate sites.”
An exclusion zone remains in place for a section of the building, and Transport’s delivery partner continues to work with the site owners and affected tenants.
Construction of the M6 Stage 1 started in January 2022 and is scheduled to open to traffic at the end of 2025. M6 Stage 1 tunnel excavation is more than 70 per cent complete.
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