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Ahead of schedule . . . Oamaru's new treated water reservoir should be operational by early 2021. PHOTO: JOSHUA RENDELL

Construction of a new treated water reservoir in Oamaru is ahead of schedule and it is expected to be operational by early 2021.

Earthworks for the $4.7million project to increase treated water storage for the greater Oamaru water network and safeguard the supply started in March and the contract for the build was awarded to Concrete Structures (NZ) Ltd just before lockdown.

Construction of the reservoir started in early June.

“[It’s] progressing very well . . . we are approximately one month ahead of construction schedule,” project manager Joshua Rendell said.

“The lockdown period affected the timeline somewhat. It did, however, give us time to complete pre-construction activities (design review, final due diligence, contractual documentation, etc), so when lockdown was lifted we could get stuck in to construction.”

The new reservoir will add 8.7million litres of water storage to the Oamaru network.

“This was found to be needed when we had the storm event during November 2018, where the ability of the treatment plant was found impacted due to the highly turbid water,” Mr Rendell said.

“With more storage, we are able to conduct longer cleans of the membranes at the plant, ensuring it recovers quicker during those times.

“The two reservoirs will hold enough water to run the network for an extended period and adds a factor of safety to help ensure water supply continuity.”

The council received six offers in the tender process. It had budgeted $3.5million for the project, but approved a new budget of $4.7million on March 18, to meet the increased standards set in New Zealand after the Christchurch earthquake and the requirement for extra earthworks. The extra $1.2million was to be sourced from development contributions (20%) and a loan (80%).

The budget had been “mostly unaffected” by the lockdown, Mr Rendell said.

“There was a slight cost increase due to the lockdown .. we needed to put some extra gravel down to ensure we kept out of the mud.”

The greater Oamaru water network services Oamaru, Weston, Enfield, Kakanui, Herbert, Hampden and Moeraki.