A route across the river is needed to pipe water from the Jacobstown wells to the East Gore Water Treatment Station and back.
In May, Gore district councillors voted to start exploring options to lay pipes under the river and Beca was commissioned to complete a geo-technical investigation into proposed drilling sites.
Councillors were updated on the progress made by the project at the council’s assets and infrastructure committee meeting yesterday.
In a report tabled at the meeting, Three Waters assets manager Matt Bayliss said expressions of interest for the drilling component of the project were called for in June and there was only one joint submission from Fulton Hogan and drilling specialists Hadlee and Brunton.
Given the technical complications associated with the job, the companies advised they would only consider undertaking the work under a design-build contract model.
"In brief, the way this is proposed to work is that the council would engage the contractor to undertake the required drilling design work so that the risks and costs can be accurately understood," Mr Bayliss said.
When these were known and if the price and level of risk were acceptable to the council, the contractor would then be engaged to undertake the drilling work.
However, if the council decided the cost and or risk was too high it would have the option of terminating the contract and considering alternative options.
Hadlee and Brunton had reviewed the geotechnical results and had not raised any significant concerns.
The next step in the project was to negotiate a design-build contract with Hadlee and Brunton.
During the discussion, Gore District Mayor Ben Bell said he was glad councillors had made the decision to drill under the river given the December 31, 2025 deadline Taumata Arowai gave councils to bring drinking water up to the new standard.
"I know it’s highly technical and there’s a long road to go but I’m glad at least we’ve got a shot to meet those regulations."
Cr John Gardyne asked whether there would be one tunnel or two for the pipes and what size the pipes would be.
Three Waters project engineer Terry Trotter replied originally two pipes of 225mm were proposed but now four pipes of a smaller diameter had been suggested by Hadlee and Brunton.
"[This] would give extra capacity over and above the two pipes ... initially asked for plus it’s reducing their risk."