Whanganui Port completes contamination investigation before final redevelopment stage
Whanganui Port found “several areas of significant contamination” after tests across its redevelopment site.
Port chairman Mark Petersen told the Chronicle contaminants included asbestos and hydrocarbons, which were factors in similar projects across the country.
“Like all ports, it’s an old industrial site and it worked through a time when contamination wasn’t considered at all,” he said.
“Stuff was dumped in rivers and on land. Whanganui is no different.”
He said pockets of contamination were found primarily around Wharf 2, the final part of the redevelopment project.
“Methodology is still being looked at, but there will most likely be sheet piling and sealing.
“Effectively, [contamination] can’t get past the barriers we put in along the edge of the river.”
The first two phases of redevelopment work, Wharf 3 and a vessel hardstand, were operational, with the defects period still being worked through, Petersen said.
Sheet piling was in place at Wharf 3 and some contamination had been encapsulated behind it, he said.
“Asbestos is an inert product when it’s not airborne, but there’s been a lot of it and there’s still a pile there we need to address as part of future works.”
In 2024, Petersen said possible sources of the hydrocarbons were the railway track that ran through the site or old fuel tanks above it.
Environmental chemist and senior lecturer at Massey University Dr Nick Kim said there were environmental controls and rules in the mid-20th century, enforced by sanitary inspectors or “hygiene officers”.
“But they were nothing like what came in with the RMA [Resource Management Act] in 1991,” he said.
“From the mid-1970s onwards, analytical techniques were developing further and there was a better understanding of the longer-term effects of cumulative contamination.”
Petrol stations and tanks could be a source of contamination, he said.
“In the 1990s, most fuel stations were pulling out their old steel tanks and replacing them with double-skinned fibreglass.
“A lot of sites were remediated and shut down, but fuel that has leaked into the ground is very hard to get out again.”
Petersen’s report to this month’s Whanganui District Council council-controlled organisations and economic committee meeting said several areas of significant contamination had been identified.
“A comprehensive contamination management plan is currently being worked through.”
Pricing and concept design for Wharf 2 were awaited from Emmett’s, and a wastewater treatment plant was now operational on the site, it said.
Petersen told the Chronicle experts had done detailed surveys but “whether it’s every piece [of contamination], we’ll never know”.
“You can only drill so many holes.
“I think we are in pretty good shape and iwi have been very helpful in terms of dealing with the process. It’s a combined effort.
“Te Awa Tupua legislation sets some pretty clear guidelines.”
The Chronicle previously reported the port redevelopment budget was about $50 million.
Revised figures remain under wraps while an independent review of the entire project by Peter Leslie of PDL Consulting is ongoing.
In June, port project director Dave Withington told councillors contamination had cost close to $6m, with $360,000 spent on designs and planning for Wharf 2.
Petersen said the port was “doing line by line reviews of where we are”.
“Contamination has been one of the issues that’s contributed to increased costs over the time of the project.
“We are just trying to make sure we limit the risk of its cost impact.
“It’s a very complicated environment and we’ve got to make sure it’s done right.”
Kim said historical port sites had handled huge volumes of materials, including fertiliser, which left an imprint.
“It’s definitely not a surprise that they keep finding things with each new stage.
“But it’s a case of dealing with legacy stuff, not new contamination, or very little.”
Remediation rather than removal was often the preferred method, he said.
“You’re not digging up thousands of cubic metres of material and trying to figure out where to put it.”
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 Whanganui District Council.