First stage of channel deepening project begins soon
One of the world’s largest dredges, the Fairway, will sail into Lyttelton Harbour in August as the Port’s channel deepening project gets underway.
Lyttelton Port Company was granted resource consent in March 2018 to dredge the harbour shipping channel to increase its draught.
The 230 metre-long Fairway will collect silty clay from the seabed of the harbour, as it works to widen the navigation channel by 20 metres and deepen it to allow vessels with a 13.3 metre draught to call at Lyttelton.
The first stage of work will see the Fairway lengthen the channel by 2.5km.
The channel deepening, which will allow bigger ships to access the Port, will provide Canterbury’s importers and exporters the best possible and most cost effective international shipping solutions.
The initial stage of the dredging programme has been awarded to Netherlands-based contractor Royal Boskalis Westminster N.V. – a global operator with more than 100 years’ experience. Built in 1997, the Fairway is one of Boskalis’ 30 trailing suction hopper dredgers.
The Fairway will make its journey from Mumbai, India, after completing its latest project – and make a stop in Singapore for a thorough clean before heading to Lyttelton Harbour. The Cawthron Institute has worked with LPC and Boskalis to develop a biosecurity plan.
In Singapore, it will go into a dry dock to be water blasted and have its antifoul refreshed. The interior spaces will be cleaned and flushed with fresh water. After being inspected, it will sail directly to New Zealand.
Cawthron Biosecurity Team Leader Oli Floerl says, “LPC has been very pro-active in making sure this dredge has minimal biosecurity risk.”
In anticipation of the channel deepening, LPC has already implemented the largest environmental monitoring programme ever undertaken for a New Zealand dredging project.
Environment Canterbury is satisfied that LPC’s plans balance what is best for the environment, the community, and the growing regional economy.
While the Fairway is hard at work, a plume will be clearly visible from the dredge, but LPC Environmental Advisor Jared Pettersson says this is a normal aspect of the dredging process on the sea floor.
“Fine sediment will be stirred up on the sea floor during the dredging process, so we can expect to see a consistent plume during the works,” Jared said.
“The environmental effects of the plume were evaluated during the consent process. It was found any environmental effects would be minimal and short term as the ecosystem is used to naturally occurring fluctuations in water clarity.”
“We have implemented New Zealand’s most robust real-time water quality monitoring system that will ensure the proposed dredging does not result in adverse outcomes for the environment.”
LPC achieved a mediated outcome with Ngai Tahu with regards to protecting the environmental and cultural values of Whakaraupō and Koukourārata.
As a result, LPC will cease dumping dredge spoil, from a previous consent, at Awaroa/Godley Head, Livingstone Bay, Breeze Bay and Mechanics Bay which are important breeding grounds for kaimoana.
The Company will pay Te Rūnanga o Koukourārata and Te Hapū o Ngāti Wheke fisheries enhancement funding that will be used on projects to enhance mahinga kai within Koukourārata and Whakaraupō (Lyttelton) harbours. There will be strict environmental limits for dredging and dumping spoil.
LPC Chief Executive Peter Davie has thanked Iwi for the positive and constructive way they approached mediation.
LPC’s Harbour Watch website will provide real-time data as part of the Company’s water-quality monitoring project.
Data Collected from 14 water-quality monitoring buoys placed in the harbor will be available 24/7 at www.lpcharbourwatch.co.nz
How Dredging works
- A dredge has suction pipes that move slowly over the seabed, collecting silty clay like a giant vacuum
- The mixture of silty clay and water is pumped into the hopper of the vessel
- Dredging stops when the hopper is full, the dredge then releases the sediment to an agreed offshore site
- The dredge will discharge the sediment through doors underneath the vessel