Environmental checks in place for Manawatū Gorge replacement highway project

Monday, 27 May 2019

One of the slips which has closed State Highway 3 through the Manawatū Gorge, necessitating the building of a new road.

Building a new highway between Manawatū and Hawke's Bay will be a big job, but caring for the environment along the way may prove just as taxing.

The Department of Conservation is staying tight-lipped on the recommendations for the new highway, despite commissioners going against what the department asked for.

Commissioners released a series of recommendations on Friday, the result of weeks of hearings about the proposed new State Highway 3 across the lower North Island.

The highway, a four-lane road from Ashhurst to Woodville across the Ruahine Range, would replace the gorge road, which closed in April 2017 due to landslips.

* Commissioners mostly supportive of Manawatū Gorge replacement highway plans

* The road to a new Manawatū-Hawke's Bay highway has a long way to go**

While the result for cyclists and the fate of the Ballantrae research farm – good and bad, respectively – were keenly awaited, the environmental impact of the road took up large chunks of the 89-page report.

Ecological impacts were the second most raised concern in submissions on the NZ Transport Agency's highway plan, which would result in removal of long-standing forests, swamp maire and wetlands.

An ecologist said 32 hectares of habitat could be lost if the road was built and there were fears rare bats, lizards, birds and invertebrates lived in the path of the road.

The Department of Conservation opposed the highway construction, largely because it thought the agency did not have enough information on the environmental impact.

The department's legal counsel at the hearings said it believed the positive social and economic impacts of the highway did not outweigh the negative effects on biodiversity.

In their report, the commissioners said the agency's mitigation plans were largely up to scratch.

The department's Manawatū operations manager Moana Smith-Dunlop gave little away in a statement to Stuff, only acknowledging the report being published and the next step in the process – the agency either accepting or rejecting the recommendations.

'We look forward to learning of [the agency's] decision in due course.'

The commissioners said much of the indigenous plants along the route were cleared and converted to pasture some time ago. However, there were forest remnants in gullies made up of mānuka, kānuka and old growth forests.

Building the route did have the potential to adversely affect habitats for some species.

Preliminary studies had found no evidence of bats, lizards or invertebrates in those areas, but the nearby riverbed was used by wetland birds.

The agency's proposed plan of replanting, pest control and improving already degraded ecosystems was appropriate, the commissioners said.

They recommended more trees be replanted than those destroyed by building the road, with different kinds of vegetations having different replanting ratios.

There would also be limits on the amount of vegetation removed.

The most strenuous recommendations relate to maire tawake, also known as swamp maire, a threatened species.

It was recommended 100 new trees be planted for every one damaged, and 200 new trees for each one which died.

Pre-construction sweeps should be done of riverbeds and habitats to ensure no native animals were harmed, and any found should be relocated.