Hill Street Water Main Renewal
The general methodology for construction is to duplicate the existing cast iron main with the appropriate size PE pipe alongside the existing main which remains live, and to tie in to the existing main at the end points to produce two live mains.
East Perth WA
Aug 15 – Oct 15
- Pipeline construction
- Water mains
- MSCL sintakote installation
- PE pipelines
- Sewer pressure main
- Trunk water mains
- Distribution mains construction
- Water main replacement
The majority of the water reticulation infrastructure in the Perth CBD and surrounds is constructed from cast iron pipe and ranges from 60 to 80 years old. Water Corporation has implemented a programme to progressively replace the entire network over the coming years to avoid further pipe bursts, which are becoming a common occurrence as the network exceeds its service life. The scheme is being managed by the Perth Region Alliance (PRA), a joint venture between Water Corporation and Programmed Maintenance Services.
PRA approached DM Civil as a reputable civil contractor and provider for Water Corporation, to join a small contractor group to participate in this strategic scheme. The general methodology for construction is to duplicate the existing cast iron main with the appropriate size PE pipe alongside the existing main which remains live, and to tie in to the existing main at the end points to produce two live mains. The existing service connections are then cut into the new PE mains carried out as night works and the existing main abandoned.
DM Civil was selected as a contractor for high profile works which require management systems in line with the inner city environment. The water infrastructure replacement programme will eventually upgrade the entire city centre network.
Significant achievements and benefits
The contract required the replacement of a 400 metre section of cast iron pipe along Hill Street using a combination of open cut and trenchless. Working alongside and across existing services in a safe and efficient manner was key to the success of the project. A set of 8 communications cables on Goderich Street forced the pipe to a depth of 3 metres.
Horizontal directional drilling was utilised for over 250 metres of pipe installation. This was carried out with a precision that was required to ensure adequate clearance from a variety of existing services including a high pressure gas main. This method also ensured that major road intersections were kept open throughout the works. This was particularly important at the Wellington Street end of the works which is a major thoroughfare for buses and emergency services vehicles. Trenchless construction methods also produced savings in road reinstatement.
Switching the property connections over from the old main to the new was a challenging task. A key requirement of the contract was to restrict to an absolute minimum, the disruption to water services for the users along the route. This was important for key customers, users who were classified as emergency services or special needs clients. Shutdowns were planned through the region as nightworks, and DM Civil crews carried out all cut-ins and connections under the supervision of the works inspectors.
As a general rule, the new mains are laid under the existing road pavement. This is required to provide sufficient separation from the existing main which must remain live throughout the process. This then requires full depth reinstatement of the pavement to City of Perth standards with the construction and reinstatement process carried out under full traffic control. As with the connections to the existing mains, night work is the only time that this is allowed.
Constructing the works in discrete stages with minimal disturbance to end users provides a positive outcome for the client resulting in future selection of DM Civil as a contractor for sensitive works projects.
Download the Hill Street Water Main Renewal project report