Case study – Tauranga Harbour dredging for next generation container ships

The Port of Tauranga is the largest export port by volume in New Zealand. The Port and its shipping channels are identified as regionally significant infrastructure in the Bay of Plenty Proposed Regional Policy Statement. The Port of Tauranga Limited holds consent to occupy areas of the coastal marine area to enable the management and operation of port-related commercial undertakings that it acquired under the Port Companies Act 1988. The consented area includes a 10 metre radius around navigation aids and a strip from 30 to 60 metres wide along the extent of the wharf areas at both Sulphur Point and Mount Maunganui. ²⁸³³  In early 2013, the Minister of Conservation granted resource consent for the Port of Tauranga to dredge sediment in order to widen and deepen its shipping channels, creating space to provide access for larger vessels.

The dredging project will widen and deepen the shipping channel from 12.9 metres to 16.0 metres depth at low water. Ships of up to 347 metres in length and 14.5 metres draught will be able to be accommodated in Tauranga Harbour. ²⁸³⁴  The first stage of dredging will give access to ships with a capacity of 5,000 to 6,000 TEUs (twenty foot equivalent containers). The biggest ships currently using the port can carry around 4,500 TEUs. The second stage of dredging will accommodate 8,200 TEU ships, future-proofing the port for the next 15 to 20 years. The expansion will also allow larger bulk cargo and cruise ships to visit Tauranga.

The Bay of Plenty Proposed Regional Coastal Plan 2014 recognises that capital dredging is required for the Port of Tauranga to deepen or widen existing shipping channels or berths, or to establish new shipping channels or berths and that there is a potential for significant adverse effects when establishing new navigation channels or berths. The volume of dredgings from the Port of Tauranga makes full land-based disposal impractical. The dredged material will be predominantly clean sand, and the majority will be placed in existing off-shore deposition sites which have been in use since 1968. There are also a number of near-shore sites that have been designed to replenish beaches at Mount Beach, Ocean Beach, and Pilot Bay. ²⁸³⁵

There are also further works proposed to complete, extend and/or upgrade the wharfs, berth areas and navigation channels. The redevelopment work includes 170 metres of additional berth at Sulphur Point, two new container cranes, six additional straddle carriers and some reconfiguration of container storage and handling facilities. These works are designed to provide for growth and more efficient use of the existing port area, but may have adverse effects on the environment. ²⁸³⁶

The resource consent conditions include the setting up of a trust with local iwi, the port and other stakeholders to set priorities and set aside funding for future harbour improvements. In addition, there is a minimum separation distance of the dredging from Te Kuia Rock (a sacred rock), the development of a Kaimoana Restoration Programme to mitigate the effects on local seafood especially the pipi beds, and the setting up of tertiary and post graduate research to promote better environmental health of the harbour. The Tauranga City Council is now in the process of preparing a resource consent application to the Bay of Plenty Regional Council to use some of the Port’s dredged sand to renourish several harbour reserves including Kulim Park, Memorial Park, Fergusson Park and the Maxwells Road Esplanade Reserve to improve the coastal amenity in these high-use recreational areas.

Last updated at 2:11PM on February 25, 2015