Thorp Street Water Main | Tasman District Council | Three Waters
Client: Tasman District Council
Project Type: Three Waters
Project Manager: Dan Roberts
Location: Motueka
Challenge
Replacing a hazardous main - without disrupting the community above it
The Tasman District Council identified an ageing DN80 asbestos cement (AC) water main running beneath Thorp and Everett Streets as a critical risk to the network. Replacing it meant working within a live urban corridor, maintaining uninterrupted water supply to every connected property, and managing traffic in a constrained streetscape where fully grown street trees prevented straightforward trench routes.
On the Everett Street section, a further complication emerged: tidal groundwater rose high enough to regularly flood open excavations. Any fixed-hours construction programme would be unreliable. Meanwhile, key valves required for the new DN150 infrastructure faced long procurement lead times - a risk to the entire project programme if not addressed immediately.
Public acceptance was also a live challenge. With access affected for an extended period, the project team needed a proactive, structured approach to community engagement—not a reactive one.
Approach
Flexible programming, early procurement, and relentless communication
BPM provided project management and client representative services throughout, delivering oversight across programme, health and safety, traffic management, and community consultation.
The new uPVC main was routed along the carriageway edge rather than through the verge, avoiding removal of established street trees and the associated resource consent complexity. Existing network connections at both ends and mid-section were reconnected to the new pipe, and a new DN150 sluice valve and fire hydrant were installed to upgrade firefighting capacity and enable future line flushing.
To tackle tidal groundwater on Everett Street, the team worked collaboratively with the contractor to programme works in short sections with flexible shift start times keyed to tidal cycles—ensuring excavations were always open during low-tide windows. This avoided costly dewatering and maintained safe working conditions.
Material risk was resolved early: orders for long-lead valves and fittings were placed immediately upon contract award, preventing supply delays from becoming programme delays. Continuity of the contractor's on-site crew was maintained throughout, which proved critical to the repetitive nature of reticulation installation.
Community engagement ran as a parallel workstream. Progress reports with section-by-section completion estimates were distributed proactively, giving landowners clear visibility of when their access would be restored. This transparency kept complaint volumes at zero throughout construction.
Outcome
Delivered early, under budget, with an exemplary safety record
The project was completed ahead of programme, reducing traffic management costs and minimising inconvenience to the surrounding community. Final outturn came in under the $2.4M budget. The health and safety record was strong, with multiple positive observations recorded and no significant incidents across the works.
Completed ahead of schedule
Early completion cut traffic management costs and reduced disruption duration
Delivered under budget
Efficient programming and early procurement kept costs below the $2.4M ceiling
Zero major complaints
Proactive community communication resulted in no significant landowner grievances
Network modernisation
AC main permanently retired; new DN150 valve and fire hydrant improve long-term operability
The existing DN80 AC main was concrete-capped in place following commissioning of the new main, eliminating the risk from the network without the cost and disruption of full excavation and removal. The upgraded infrastructure now supports improved firefighting capability and simplified future maintenance flushing.
Water infrastructureAsbestos cement replacementuPVC reticulation3 WatersCommunity consultationTraffic managementTasman DistrictProject managementHealth & safetyAsset renewal
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