Willis Street watermain renewal
Value of project: $399,000
Client Council: Wellington City Council
Main contractor: Transfield Services Infrastructure Ltd
Timeframe: 27 December 2008 - 30 January 2009
Background:
Digging up the road in the middle of the Wellington CBD is always a challenging proposition and when failures occurred on a section of watermain in Willis Street, between Manners and Ghuznee Streets that is exactly what Capacity Infrastructure Services was faced with.
Although the failures were not widespread they were isolated to a section of pipe mainly in the vicinity of the busy Dixon Street intersection. Testing was carried out and confirmed there was a failure in the pipe material.
Network analysis was undertaken and determined that we should use 200mm ductile iron pipes using the open trenching method along the existing alignment between Manners Street and Ghuznee Street. This section of Willis Street is narrow and we knew that relaying the watermain would be difficult and have a significant impact on traffic flows.
The physical work contract was awarded to Transfield Services Infrastructure Ltd and GHD Ltd was the lead consultant.
Challenges:
The main challenge faced was traffic management in such a busy part of the central city. To help alleviate traffic disruption we worked with the Council to obtain approvals to work during the normal Christmas shutdown period to take advantage of the quieter roads during the holiday period.
Only a short section of the road was worked on at any one time enabling us to ensure two-way traffic flow with speed restrictions.
We also needed to manage planned shutdowns during certain periods of the work. We ensured all residents and business owners were notified in advance.
Success:
This project was delivered on time and although it came in slightly over budget the Council was happy because it was completed within the timeframe to a high standard. Unforeseen resealing work that needed to be undertaken caused the budget overrun.
As part of the projects Communications Plan, residents and business owners were consulted prior to commencement and buy-in obtained for the work. This resulted in minimal complaints received.