Johnsonville sewer main upgrade
Value of project: $2.2 million
Client Council: Wellington City Council
Main contractor: HEB Smithbridge Ltd
Timeframe: April 2007 – April 2008
HEB Smithbridge contractors renewing the pipes along State Highway 1.
Background:
During 2007 Capacity Infrastructure Services project managed the installation of 800 meters of sewer pipes and the associated manholes as part of the Johnsonville main trunk sewer replacement project for Wellington City Council. The work involved replacing the existing undersized main trunk sewer which was unable to cope with the needs of the expanding suburb. As a result the surcharge of wastewater back into local properties was occurring in certain conditions.
The replacement work involved crossing State Highway 1 and laying a new sewer along Johnsonville Road, under State Highway 1 and alongside the highway to connect to the existing trunk sewer. Due to the location and peak traffic flows open trenching was not an option and instead pipe jacking was chosen as the best option.
The $2.2 million work was scheduled to begin in April 2007 and was originally programmed to take six months. The work actually took 12 months to complete due to bad weather and unforeseen ground conditions and obstacles.
Despite the time over-runs the project was completed under the estimated cost to the satisfaction of Wellington City Council and the local community. The lead consultant for the job was Maunsell Ltd and the lead contractor, HEB Smithbridge Ltd.
Challenges:
The location next to State Highway 1 was a major issue for the project team meaning effective traffic management plans became critical to the success of the project. Capacity Infrastructure Services worked hand-in-hand with the Council’s Road Protection Team to ensure traffic disruptions were kept to an absolute minimum.
Having a good relationship with the community was also critical to the success of the project especially when the work started to go over deadline. There was a need from early on to engage and inform the local community about the importance of the work as all they could see was disruption and not what was happening beneath the streets. One way this was achieved was by inviting the two local residents’ associations to join the steering group. The steering group was able to take on board advice from the residents’ associations for informing the community which included displaying information in the local library and other ideas for communication. Through their involvement with the steering group the associations had a better understanding of the importance of the work and helped to champion this in the community.
Running behind schedule due to bad weather and unforeseen ground conditions and obstacles produced its own set of problems meaning the work stretched out into the Christmas period. All work in town centres must halt for about a month to meet the Wellington City Council’s requirements in the Code of Practice for Working on the Road. This resulted in completion taking 12 months rather than the six.
Success:
Delivering this project on budget for Wellington City Council despite over-running the original timeframes was a positive outcome for Capacity Infrastructure Services as was the community buy-in which enabled the work to continue with understanding from locals as to why it was so critical.