Replacement of Wingham water pipeline after major floods now expected to cost $6.5 million

Ongoing work to restore the Wingham water supply pipeline damaged in the May floods is now estimated to cost $6.5 million to complete – with the budget blowing out by $2.4 million.

Works to restore water supply are expected to be completed in December this year, more than six months after the damage.

So, why is it costing so much – and what’s taking so long?

What happened? In May, the primary pipeline connecting Bootawa Dam with the service reservoirs in Wingham was severely damaged where it crossed the Manning River.

The pipeline was broken in three places, unexpectedly cutting off supply to the town's reservoirs, and deemed unrepairable during the heavy rain and record-breaking flood event. Instead, the pipeline will need to be replaced.

👷‍♀️What’s the fix? A design and construction contract has been entered into for all the required emergency works with Eire Constructions Pty Ltd – previously used contractors from the Gloucester Reservoir project.

What’s been done so far? After the floods, local and specialist contractors were engaged to carry out investigations to refine the scope of works to replace the damaged pipe. This included divers for underwater inspections, as well as land, riverbed, and geotechnical surveys.

Access to the site was difficult, with only 4WD access available. Within 10 days of the flood, an access road was constructed and road maintenance was carried out to cater for the increased construction traffic and large vehicles required to deliver drilling equipment and pipework. 

All the investigation works were carried out over a six-week period with the total cost about $360,000, including internal staff costs for project and contractor management.

Drilling through cobble stones:  In June, a council staff report provided cost estimates totalling $4.1 million for the project, based on bore length and pipe diameter needed to drill through the riverbed. 

The geotechnical investigation found the bore needed to be longer than anticipated due to the depth and extent of river cobbles. The conditions also required steel casing to prevent the borehole from collapsing during drilling.

A geo-seismic survey was undertaken mid-July. The report found the bore would have to go down 725 metres.

🗣️ Councillor Digby Wilson called the scale of the project “impressive.”

“I think the transparency in this is also important, so people understand why the cost has shifted,” Wilson said at the council meeting.

The works are now estimated to cost $6.5 million. 

The cost of underboring is primarily based on the time it takes to drill through the various ground layers. The harder the ground, the longer it takes to drill – which impacts the costs.

👷‍♂️ Work underway: According to council, construction works are underway. The drill rig launch pad works have been completed and a drilling contractor established on site. 

The ramming of steel casing through the cobble stones on the southern side has also begun. 

🗣️ Councillor Alan Tickle said the project was a “great thing for the community.”

“That original pipeline has been there since 1968 I believe. And so this is going to be actually tunneled underneath rock, so we're not going to have this issue again,” Tickle said during the meeting.

What’s happening in the meantime? A temporary solution to supply treated water to Wingham currently involves manual operation of multiple valves twice a day. 

It relies on a single supply pipeline from Taree South to supply all of Taree, Wingham and the Northern area of the Manning Water scheme – including Harrington.

If there are any time delays with the emergency works, there’s a high risk this temporary solution will extend into the peak summer periods and may not be able to meet water supply demand.

MidCoast council is investigating risk mitigation measures, including installation of a temporary pipe river crossing and restricting usage during the peak summer demand.

What’s the impact on the community? MidCoast council considers the impact of completing the construction works as “localised.” 

The works are within three private properties on each side of the Manning River at the end of Abbotts Road Bootawa and Abbotts Falls Road Wingham. 

There will be minor water supply disruptions during critical cutover works nearing the completion of the project. During the works, there will be construction traffic and noise for approximately three months.

The physical work of connecting the pipe is expected to be completed in November. The associated backfilling, cleanup and restoration of the site will go into December.

The easement and property issues of finalising land acquisitions will take longer to resolve, with the project expected to be wrapped up completely by March 2026.

Thumbnail: (L) Drilling is underway on Manning River Underbore (R) First steel casing being lifted onto the launch guide for ramming. Images: MidCoast Council