Wallace St - 3 Waters Diversions & Renewals

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Customer/Principal:

Brian Perry Civil/Wellington Water

Consultant:

Connect Water

Date:

June 2019 – Ongoing

Capability:

Mobile Plant Fleet, Underground Services, Traffic Management, Dynamic Pipe Bursting, Static Pipe Bursting, PE Welding

Customer Type:

Government & Local Government

Scope:

Renewal & diversion of approximately 1000m of public watermain and associated service connections.
Renewal & diversion of approximately 100m of public stormwater main and associated manholes, sumps and leads.
Renewal of approximately 300m of public wastewater main and associated manholes and connections.
Traffic Management for all contract works including the diversions and renewals package and the bulk watermain package being executed by BPC & ECS.

This project is currently ongoing. We have completed a significant portion of the water renewals package including two complete side streets (Hargreaves St & Finlay Tce). The bulk water works have also progressed significantly with work underway in Hargreaves St and Howard St. Our Traffic Management team have been servicing all of the work on site.

This project is being delivered by BPC with ECS & GPFL delivering significant portions of the physical works. We have developed strong relationships with both of these businesses over a long period of time. Those relationships have been further strengthened as we entered into a panel arrangement together to deliver BAU work for Wellington Water. This project is not part of that panel but the strong team approach is evident on this project.

Traffic Management is a critical element of the work on this project. GPFL have taken the lead with the traffic management delivery on site and in producing a large number of traffic management plans and drawings to facilitate the work. We have played a critical role in working with the Wellington City Council RCA and other key stakeholders such as the bus operators to ensure that the work can progress well on site. At any time our traffic management team is managing work by three contractors on up to five worksites across seven streets in Mt Cook. The team are performing at a high level to service this work.

At an early stage in the procurement our team identified that the only viable way to deliver this project would be under a road closure of Wallace St. The success of the project would be wholly contingent on the road closure going ahead. Once in contract we worked closely with BPC to ensure that the road closure was approved by the RCA and would be delivered on site. The road closure is planned for January 2020.

GPFL identified that trenchless technology could play an important role in minimising disruption the project. We proposed a number of trenchless methods as an alternative to the open trenched solutions that are part of the design.

125OD PE100 SDR11 watermains have been renewed offline on Hargreaves St and Finlay St by Horizontal Directional Drilling. These water mains and their services have nbow been successfully completed and are in services.

A section of 180OD PE100 SDR11 watermain has been renewed online in Wallace St by static pipe bursting. We used a Grundoburst 800G to burst the existing 150dia. CI main with a new PE pipe. Temporary supplies had been installed ahead of the work iun order to maintain service to the surrounding businesses and residences.

To cut in new valve sets and new watermains we have planned and executed 12 water shutdowns across the area. We have worked with Connect Water and the WWL operations team to deliver shutdowns that minimise service interruption and we have liaised with surrounding businesses to understand their constraints during the planning process. In some cases we have encountered unknown issues with the existing network that have required repair in order that the work could proceed and we have worked with WWL customer operations group to assist with those repairs.

PE welding both Butt Fusion and Electrofusion have been undertaken extensively on the project. We have delivered that welding under an approved weld procedure that included pre-construction and construction destructive weld tests. This regime of testing has been completed successfully.

The PE mains have been successfully tested (Pressure Rebound Test), chlorinated and bug tested prior to being cut in to the main.

To date this project has been an interesting challenge but the project team of GPFL, BPC & ECS have worked collaboratively to overcome any issues. The traffic management portion of the scheme has been delivered to a high standard and, along with innovative use of trenchless technologies, has set the project up for success.

A valve and hydrant set ready for backfill

Installation of a 125OD PE100 SDR11 main by Hargreaves St.