Work under way on replacing controversial culvert in Putiki, Whanganui

Contractors are preparing to install the new box-culvert in Wikitoria Rd. Photo / Bevan Conley

Work is progressing in readiness for building the new box-culvert over the Awarua Stream on Wikitoria Rd, Putiki.

Whanganui District Council senior stormwater engineer Kritzo Venter said the 4m by 2m pre-cast concrete box-culvert units are on site.

"The contractor has built a coffer dam next to the Awarua Stream to ensure the worksite does not get inundated by the stream while the first of 10 box-culvert sections are put in place by the large crawler crane onsite," Venter said.

"Following this, 'wing-wall' structures will be put in place at each end to funnel the stream's normal water flow through the culvert – this also protects the embankments from scouring during high flow conditions."

The original culvert will be decommissioned by grouting it with concrete and the last step will be to reinstate the road surface and area surrounding the culvert.

"We will then finish off with riparian planting and enhancement of the surrounding area," Venter said.

"Fish passages will be reviewed to ensure fish can continue to swim through the culvert to breeding areas."

The new culvert is part of a wider programme, which began in 2013, to improve the Awarua Steam. The New Zealand Transport Agency is funding 61 per cent of the cost of the culvert. It is scheduled to be finished in September.

Putiki residents have been battling for years to get the council to replace the original culvert after repeated flooding of properties and homes.