Whanganui District Council needs contractors to meet water sampling regulations

Whanganui District Council will need contractors to keep up with sampling rules from water regulator Taumata Arowai.

Council senior water engineer Dave Rudolph said daily sampling had been required since the start of last year, with staff conducting them until now.

“Before the rules came in, we used to do monthly sampling and, potentially, you could go to quarterly if it fitted in the right category and within the terms of sampling,” he said,

“This is definitely a step up.”

He said sampling was conducted at multiple dedicated sites in rural and urban areas, with at least three trips to Palmerston North for laboratory testing each week.

“We’re not just taking them from the source, we’re taking them from the reticulation.

“Every sample has to get tested at the lab and we have 24 hours to get them there before they become non-compliant.”

Water for Whanganui’s urban area comes from four bores at Kai Iwi and one at Aramoho, with an auxiliary bore at the Westmere water facility on State Highway 3.

There are separate rural schemes at Fordell and Pākaraka.

Rudolph said samples were at risk of contamination from multiple sources.

“That could come from your body or the wind or the environment.

“It sounds easy - take a sample and put it into a plastic cup - but it does take time.”

Whanganui's urban area is serviced by four bores at Kai Iwi and one at Aramoho. Photo / NZME

Testing was done for a range of things, including E. coli, total coliforms, DPBs (disinfection byproducts), metals and FAC (free available chlorine), he said.

“[FAC] is a big one - making sure we have a residual in the reticulation to eliminate the E. coli and total coliform.”

Senior wastewater engineer Tony Hooper told the operations and performance committee that council officers would oversee the contractors’ work.

“Ultimately, we carry the can and have to pay the price for anything that goes wrong in that area,” he said.

“The focus is on providing a safe and reliable water supply.”

Committee chairwoman Jenny Duncan asked whether daily and weekly testing was excessive.

Rudolph told the committee it was a good thing but every council in the country was struggling with resources for sampling.

He said other departments within the council had been used to complete the work, which meant an increased workload.

The exact number of contractors required was not known, Rudolph told the Chronicle.

“Obviously, we will have some performance measures in place to make sure they are doing what needs to be done.”

A report to the committee said planning was underway for land acquisition for the district’s UV (ultraviolet) treatment systems.

All designated groundwater sources must have fully operational protozoa barriers by the end of next year.

Protozoa refers to a group of micro-organisms that include cryptosporidium and giardia.

UV disinfection kills micro-organisms by altering their DNA and impeding reproduction.

Rudolph said the new systems were expected to cost between $1.5 million and $2m, with installation taking place in years one and two (2024 and 2025) of the council’s long-term plan.

‘We have determined the sizes of the UV units, it‘s just about how we procure them,” he said.

“At this stage, we’ll have one main [plant] for the city and then a couple for the rural schemes.”

Mike Tweed is a multimedia journalist at the Whanganui Chronicle. Since starting in March 2020, he has dabbled in everything from sport to music. At present his focus is local government, primarily the Whanganui District Council.