Dormway

S1 Sewer Maintenance Hole (MH) Cone-Top Replacements

Project S1 Sewer MH Cone-Top Replacements

Client Urban Utilities

Location Brisbane, QLD

 

Scope

Dormway was engaged by Urban Utilities to remove the 3-metre-deep cone-tops on existing MHs in Kingsford Smith Drive on the 100-year-old S1 main trunk sewer.

The project included rebuilding the shafts and slabs in the roadway to conform to current WH&S standards and to facilitate pipe relining.  Dormway lined the new MH sections with a polyethylene (PE) liner to extend their design life.

Following the successful replacements in Kingsford Smith Drive, Dormway was subsequently engaged to replace additional cone-tops in Ann Street, Nudgee Road and Bowen Hills.

Outcome

Construction was expedited through Dormway’s development of innovative solutions to the original design and construction methodology which resulted in the cone-top replacements taking approximately 1 week per MH, instead of 3 weeks per MH based upon the original design, whilst also allowing the construction site to be returned to a safe, trafficable road at the end of each shift.

The project was required to be completed in a tight timeline in order to allow the sewer relining project to proceed on schedule.  Dormway successfully completed the cone-top replacements ahead of the required schedule, whilst maintaining high health and safety standards with minimal disturbance to the environment and adjacent community.

Challenges

  • Live works within 18-metre-deep shafts
  • Variable ground conditions and MH construction, with lack of available or reliable as-constructed information for the MHs
  • Working in constrained site areas with a high density of services, including both known and unknown services
  • Construction works limited to night works between 8pm and 5am, with the cone-top programme tied to the programme of the pipe relining contractor
  • Night works adjacent a residential area
  • Development of traffic management plans to allow flexibility and the ability to accommodate multiple work fronts involving various contractors along Kingsford Smith Drive which varied from night to night
  • Constricted site footprint in order to allow two-way traffic to continue to use Kingsford Smith Drive during construction works
  • A construction site that had to be returned to a safe, trafficable road at the end of each shift