Gorge work soldiers on despite brush with weather bomb


Work on the Manawatu Gorge slip has returned to business as usual after its brush with last weekend's weather bomb.

NZ Transport Agency regional state highways manager David McGonigal says that despite receiving a 40mm dumping of rain, the slip site was largely unscathed, and despite some minor setbacks, work is carrying on at a good clip.

"While the weather bomb did curtail work over the weekend, the upside is that the benching has stood up to the punishment pretty well, which is an encouraging sign."

The lower Manawatu River catchment caught a large volume of the much heavier rain from the south of the site and the NZTA understands that at the Upper Gorge Bridge the river peaked at 7m at 8pm on Saturday night.

"This has removed much of the debris that was piling up in the river, and this is both good news and bad news. On the good side, this eases the constraint on the river - and reduces the effect that any further debris will have.

"On the negative side - the 'toe' of the slip material is now what we call "over-steep". As the slip material is what supports the working platform for the benching effort and being steeper makes it less stable, this has resulted in some slumping of our working platform.

"Safety, as ever, is paramount and this put our operation on the working platform at increased risk. To ease this risk we didn't work on the narrow eastern end, and haven't been pushing material directly over the edge with dozers. We can start again when the mass has settled and in the interim we have been throwing material over with excavators instead."

Mr McGonigal says the crews are working on a platform on the fifth bench that tapers upward to the fourth bench.

"The team are getting there pretty quickly - there is just another 12m downward at the Woodville end to get the bench down to its final level - then the benching will be essentially complete and we can focus on clearing the slip itself."

The remainder of the batters (bench slopes) on the western end has now been completely hydroseeded and growth will soon be sprouting through like it has on the areas higher up.

Meanwhile at the road level, the NZTA has now started carting debris from the Woodville.

"We've been able to create a turning area by utilising the old road, returning onto Rapids Bridge, and a 25  tonne excavator is now loading up trucks from this end.

"Despite the weather bomb the Ashhurst end wasn't affected, except for a silt mass on the road, and we were able to get going again straight away. "

Mr McGonigal says the helicopter will be lifting materials and supplies on and off the benches today. It will also take up a couple of our engineers so they can check out the slip and analyse safety risks for this next stage.

Mr McGonigal says the NZTA are grateful as always to the community and motorists for hanging in there while crews get steadily closer to hitting the home straight and reopening the gorge.