Gorge slip clean-up costs rising

The cost of clearing slips in the Manawatu¯ Gorge is rising with more slips falling since the road was shut more than a year ago.

Dozens of slips have come down on State Highway 3 through the gorge since it closed in April last year, including slips on both sides of Kerry’s Wall – an area identified as the site of a potential mass landslide – near the Ashhurst end.

The New Zealand Transport Agency (NZTA) has predicted as much as 630,000 cubic metres of material could drop at that site.

NZTA regional transport systems manager Ross I’anson said the current estimate to clear the slips and deal with the Kerry Wall issue was $50 million.

The estimated time frame it would take to deal with the issue was almost three years, and could only happen once the wall had stopped moving.

At present, the wall was still moving and there were also more slips across the site and cracking in the rock face was still occurring.

‘‘There are approximately another five slips in the gorge, including ongoing slips at Kerry’s Wall.’’

I’anson said if Kerry’s Wall and the rock face stopped moving and showed over a period of time it was no longer moving, the NZTA would reassess the risk of clearing the slips in the gorge.

The NZTA announced in March its preferred route would go north of the Manawatu¯ Gorge, but south of the Saddle Rd bypass.

Traffic will use the bridge already going across the Manawatu¯ River east of Ashhurst, but veer north just before the Manawatu Gorge entry, go east across the range, then head down the other side into Woodville.

NZTA director of regional relationships Emma Speight said the chosen route was safer than the southern one, in which the road would have gone between two fault lines at one point. The chosen route was shorter by 6.6 kilometres, would be a quicker trip than the old Manawatu¯ Gorge route, shaving nearly four minutes off, and would not be as steep as the Saddle Rd, she said.

Resource consents were needed, but construction was expected to begin in 2020 and be completed by 2024, Speight said.

However, this can’t come soon enough for residents of a town flooded with traffic after the gorge closure, with a longawaited bypass stuck in the mud.

Ashhurst will continue to be inundated with an extra 5000 cars and trucks a day for some time yet, they were originally told a bypass would be built early this year. NZTA first suggested building a bypass around the town in September, saying construction would be finished by mid-2018. But a sod is yet to be turned.

The agency’s portfolio manager Sarah Downs said a construction date could not be set.

Officials had a design in mind, taking traffic around the northern side of the Ashhurst Domain, then heading between River Rd and the Pohangina River before connecting to the Saddle Rd.

However, it ran over a flood plain and would likely require lots of earthworks, Downs said.

NZTA was not able to look at buying properties ‘‘because of some issues that are quite uncertain ’’, she said.