Jet boats have joined the effort to get rid of woody debris from the banks and within the Waimatā River.
Working alongside chainsaw operators, an excavator team and a helicopter, they’re tackling almost 30km of riverbank.SUPPLIED/GDCSUPPLIED/GDCSUPPLIED/GDC
Chainsaw operators on jet boats chop up the large logs first to make it more manageable for a helicopter to collect and
dispose of at one of six burn areas. The work is ongoing for another month with the helicopter only able to operate in
favourable weather conditions. Photos from Wednesday.
This initiative is part of a wider regional programme to clear waterways and our coast of woody debris that washed
across Tairāwhiti during Cyclone Gabrielle.
It follows specialised drone work in May that captured details of where the woody debris was located.
Council Community Lifelines Director Tim Barry says there’s been significant progress with the Waimata River work but it
is weather dependant.
“There is 28.4 km of riverbank to clear of logs, and 95 percent (27km) has already been chopped up into manageable
pieces, which are then picked up by helicopter and taken to one of six burn pits established between Waikereru Bridge
and the Donaldson farm at Darwin Road.”
Sixty percent of the 28.4km riverbank has also been revisited since the June 24 weather event to address additional
debris, and debris that has moved.
The helicopter can extract a piece of wood approximately every 1.5 to 1.8 minutes and take up to 1.3 tonnes in weight.
“There’s only one pilot who flies the helicopter and controls the grapple to lift the woody debris.
“This highly skilled work is likely to be very visible over the next few weeks as we reach the lower part of the river
close to town.”
The jet boat ferries the chainsaw operators up the river to hard-to-reach places so they don't have to access private
property.
A side-by-side vehicle is also being used to cross farm tracks where possible.
Work will take a further three to four weeks to complete, however the helicopter could stay on and work around the
weather.
The helicopter started at Waikereru Bridge this week and has already moved 700 of approximately 2500 tonnes (28 percent)
to disposal/treatment sites.
Mr Barry says the jet boat has been invaluable for the operation.
“It’s also going to be crucial for our excavator crew, who will remove some of the logs while they’re still in the water
– as the riverbed sediment allows.
“This in-river work can only proceed when the helicopter is operational to prevent downstream floating of the logs that
have been freed.”
The total amount of woody debris removed across Tairāwhiti in the region-wide clean-up as at 7 July 2024 has reached
420,750 tonnes, 91.5 percent of the volume in active project areas.
Of that, 379,954 tonnes has been treated via high oxygen burning, open-air burning, or chipping
With 64,738 tonnes, 15 percent of the toal extracted volume, removed from beaches.