After input from the community and careful modelling and analysis, Napier Port has decided to amend its original proposal for where it wishes to dispose dredged material, including mostly fine sand and silt, dredged up as part of its planned development.
Napier Port will shortly be seeking consent to build a 350 metre wharf along its existing container terminal and to deepen and widen its shipping channel for the larger ships expected. It had previously considered disposing of the approximately 3 million cubic metres of dredge material at its currently consented disposal sites near to Westshore and expanding it to accommodate the larger volume.
Over the last 15 months, Napier Port has conducted a pre-consultation process prior to lodging resource consent applications, speaking with around 2000 local people, stakeholders and the broader community.
That process saw the port engaged in close discussions with groups, including divers and recreational fishing groups, who raised concerns about the proposal for significant volumes of dredge material being deposited close to shore.
Napier Port Chief Executive, Garth Cowie, says Napier Port was particularly concerned to ensure that future sediment disposal would not negatively impact the marine environment.
“While we had already invested heavily in specialist studies, we decided in November to extend those investigations to further include an off-shore disposal site as a serious option,” Mr Cowie says.
The investigations have helped us to understand how effective depositing dredge material near the shore may have been in re-nourishing Westshore Beach, as well as where the different types of sediment are likely to end up.
Mr Cowie says the studies identified that a majority of the material is not suitable for renourishment and the remainder is too fine and will move or be carried anti-clockwise, first south and then east and potentially back towards the Port’s shipping channel.
Dredging to clear the shipping channel over the last decade has yielded small volumes of sand and fine silt. However, we now know from new monitoring and improved modelling techniques that disposing of the material at the Westshore disposal site is not having any long term benefits to the beach.
“The studies showed the coarser sand that did end up on the beach was providing nourishment for a period before being carried north along the coast by wave action. The studies have confirmed the observations of many of the people we spoke to.”
Napier Port takes its impact on the environment, particularly the marine environment extremely seriously and as a result of the latest findings has decided that the dredged material from the development would best be disposed of at a site approximately 5km off-shore, directly east of the port.
This site is much deeper than the inshore site and investigations show that the deeper water means that the material disposed will be less susceptible to adverse weather events. Accordingly, any sediment is less likely to be disturbed in a significant storm.
Napier Port is pleased it decided to engage the community early in robust pre-consultation and invest in further investigations, as it now feels confident that the project will have minimal impact on the local marine environment.
“The input from stakeholders at an early stage has allowed the port to develop a far stronger wharf development and dredging resource consent application,” Mr Cowie says.