Ports Australia, the peak body representing the interests of port and marine authorities in Australia, has introduced its “Dredging and Australian Ports – Subtropical and Tropical Ports” report.
The report provides an overview of the approval processes associated with dredging and at-sea placement of dredged material, the nature of environmental monitoring programs associated with recent port related dredging projects and, through a comparison of monitored environmental impacts with those approved by government, determines that recent port related dredging projects in northern Australia have performed well.
The report relates specifically to dredging and at-sea placement of dredged material in subtropical and tropical Australian ports (northern Australia) as:
• large capital dredging projects are frequently occurring and proposed in these regions (eg for mineral resource development in the Pilbara and Queensland);
• public interest is focused on dredging in these areas (eg the Great Barrier Reef Region);
• because dredging environmental risks and associated management needs differ to southern temperate regions of Australia. Legacy contamination issues are much less frequently involved in dredging projects in northern parts of Australia than the historically more developed parts of southern Australia where dredging in old established ports with a long industrial history can involve large volumes of contaminated sediments that require specific management approaches.
A complementary report will be prepared in the near future that relates to Australian ports located in temperate areas and the environmental performance of their dredging projects.
The Importance of Ports and Shipping to the Australian Economy
Australia, being an island country, relies heavily on its maritime links with some one third of the GDP generated by seaborne trade.
Australia is the 12th largest economy in the world (IMF 2012) and has the fourth largest shipping task. Its ability to trade goods with the world and grow the Australian economy depends heavily on ports. Efficient, commercial ports are critical for the export of the agricultural and mineral commodities and for a range of imports including household goods, manufactured products, vehicles, machinery and fuel. Maintenance and growth of the economy depends directly on seaborne trade.
Ports are the largest freight hubs servicing these trades and a major component of Australia’s international supply chains. The capacity of ports to operate efficiently directly impacts the ability to grow and develop as a sustainable society.
The Need for Dredging and At-Sea Placement
Shipping channels are of equal importance to the road and rail networks and, like these networks, need to be maintained and developed as trade grows.
Dredging of shipping channels is an essential part of port operation in Australia and globally. Although shipping channels are declared in naturally deep-water areas, thus enabling the safe passage of shipping, dredging will always be required.
Maintenance dredging is regularly required to remove sediments (eg silts) that have been transported by currents from nearby areas and accumulate in the artificially deepened channels and berths.
Maintenance dredging is essential to remove shoaling and maintain designated channel depths so as to allow ships to safely access wharves and associated road and rail connections. Capital (also termed developmental) dredging is also required to create new or improve existing channels and berths.
Channel widening and deepening is necessary to ensure ports can accommodate the increasing numbers of ships trading with all Australian ports as the international economy grows and larger ships are used to achieve economies of scale. Ports in northern areas of Australia are being developed or expanded to meet the growing mineral resource export trade and regular channel improvements will be required (major size increases in bulk vessels have occurred over the past few decades given the cost advantages and may continue in the future).
Dredging may necessarily involve placement of material at sea. Land based or reuse options for dredged sediment are often not viable in northern Australia where adjacent coastal lands may have high conservation or cultural value or are viable only for small amounts of material or one-off projects. Recent technical studies for the Great Barrier Reef Strategic Assessment concluded that on land placement of dredged material (particularly fine grained maintenance material) was not a long term viable option for the six major ports in the Great Barrier Reef region (SKM 2013a).
Material placed at sea must be non-toxic and placed at an approved Dredged Material Placement Area (DMPA). DMPAs form an essential part of the port infrastructure, their location and operation taking into account environmental, social and economic considerations. Port related dredging and, for many ports, at-sea placement of dredged material is an economic imperative required to maintain and develop shipping channels.
It ensures that the supply chains to overseas markets can operate efficiently, provides economies of scale and enables the Australian economy to grow in an increasingly competitive global market.
April 24, 2014