Rotokauri Bulk Watermain


  • Location: Hamilton
  • Year: 2017/18

Technical Overview

Key project features include: Approx. 827m of open trenching, 1898m of horizontal directional drilling, a sleeve under the railway and six connections to existing pipework.

To install, test and commission 385m of DN550 CLDI and supply, install, test and commission 442m of DN500 CLS, 823m of DN630 PN12.5 PE100 and 1075m of DN560 PN12.5 PE100 bulk main and all associated valves, flow meters and other fittings and connection works in accordance with the contract documents.

This includes supply of all plant, labor, materials and incidentals necessary to complete the construction. The scope involves approximately 827m of open trenching, 1898m of horizontal directional drilling, a sleeve under the railway and six connections to existing pipework.

The Rotokauri Bulk Watermain project covers nearly three kilometres, running from Pohutawaka Drive to the intersection of Aorangi Road and Te Wetini Drive in northern Hamilton. Watermains, stormwater utilities, wastewater and other services like power, gas and telecommunications exist in the area, which makes placing the new watermain a challenge.



Drill Section

Sub-contractors, CDS New Zealand Ltd, have done a brilliant job with three shots now complete. This has brought us from the end of Te Wetini Drive right through to Pukete Road, meaning more than three-quarters of the total distance has been covered.

The drilling so far hasn’t been without its issues, of course, but the team has stepped up, developing appropriate solutions every time. At one point during the project we dealt with sections selling after welding the 800m pipe string weighing a total of 78 tonnes. This meant we had to cut the pipe and use two of the 30 tonne excavators to manoeuvre and squash it into two sections, stretch it out and reweld it, before we could pull it in.

On the first shot (400m long) the pulling head pulled off. The second shot (600m long) saw the pipe get stuck at 6m deep. On the third shot (800m long) it happened again, when the pipe got stuck 30m from completion. CDS’s crew, along with Connell’s staff, worked through the night and into the following day to get this string in. Racing against the clock to get this pipe in the ground and avoid large penalties from property owners, CDS put their thinking caps on and with a few sheetpiles and a bit of concrete the drill rig was reset and the last 30m finally came in. This was a mammoth effort and a great result. The pull was one of the longest pulls in New Zealand for this size pipe.

CDS has set up for the final 220m shot along Pukete Road. This will bring us to the tie in point of the open cut section at Cullimore Street.

Open Cut

We have completed the open cut section up Cullimore Street, which includes testing, and are now working along Highland Drive. Great progress has been made with a timely run of fine weather proving extremely helpful. The expectation is that Highland Drive will be installed by the end of May with road reinstate to follow. Then we will move on to the final section along Pohutukawa Drive.

The team is following behind installing all the connection points. To date we have completed two cut-ins to the existing 250mm mains, with Highland Drive scheduled next for completion. These cut-ins are quite delicate and require high focus and precision to get all the levels right. We are also onsite installing the last section of 560 PE and completing the work around the tie-in point between the 630 PE pipe.

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