ESIAs for Marine Works

Even in the face of potential global recession, the demand for natural resources driven largely by China and India, continues unabated. Demand for raw materials such as iron ore and coal remains buoyant and, in response, mining companies throughout the world have ramped up production. One of the potential bottlenecks in the supply chain is capacity at export ports and terminals, and South Africa is no exception in facing this problem. Environmental approvals are required before port expansions can proceed and, given the sensitive nature of port environments, obtaining such approvals can be a protracted process.

SRK Cape Town has been involved in Environmental and Social lmpact Assessments (ESIAs) for a number of port and terminal expansion projects in recent years. Preparing ESIAs for upgrading both the Ports of Cape Town and Saldanha has presented a number of challenges concerning potential impacts on the marine environment. One key component, with the potential to generate significant impacts, is dredging. As the sise of vessels being used internationally increases, port upgrades must make allowance for larger vessels, with deeper draughts that in some cases require large turning circles. As a result, entrance channels, berths and turning circles must be dredged.

Dredging activities in themselves cause impacts, such as:

• Disturbance and destruction of coastal and benthic flora and fauna (i.e. organisms that live on the ocean floor)
• Increases in sediment loads in the water column, with secondary impacts on the marine ecosystem
• Impacts on water quality, which could affect other users in the area (e.g. mariculture industries)
• Impacts associated with blasting (noise, vibrations and shock waves) with effects on marine mammals and birds as well as potential impacts on port and surrounding structures

In addition, a range of potential impacts is associated with the disposal of dredge spoil, which often takes place offshore. These include:

• Disturbance of benthic flora and fauna at and around the disposal site
• Increased sediment loads in the water column, with the effects of smothering benthic organisms, as well as temporarily reducing the amount of light that can penetrate the water column
• Increases in shipping traffic due to interruptions in regular ship movements, as well as increased risks of collisions between barges transporting dredge material and regular shipping traffic
• Possible interference with fishing and navigation
• Potential for dredge material to wash up onshore, if not disposed of at a suitable depth

Port upgrades are usually undertaken in phases, allowing areas of the port to continue operating normally, while other portions are undergoing upgrade. However, impacts are especially significant where ports are located near wetland sites identified by the 1971 Ramsar Convention as needing protection, which occurs surprisingly often: both Cape Town and Saldanha are near Ramsar sites, as is a new project for the expansion of a Namibian port which SRK is working on.

Apart from the ESIA required for upgrades of harbours, offshore disposal of dredged material – “dumping of waste at sea” – requires additional permits, which are often driven by international conventions and protocols.

South Africa is a signatory to the 1972 Convention on the Prevention of Marine Pollution by Dumping of Wastes and other Matter, an international treaty that limits the discharge of wastes that are generated on land and disposed of at sea. The London Protocol 1996 is a separate agreement that modernised and updated the 1972 London Convention, and will eventually replace it. South Africa is a Contracting Party to the London Protocol 1996 and must adhere to its stipulations.

Due to the nature of port activities, sediment within and surrounding ports (including approach channels) is highly likely to contain pollutants, e.g. heavy metals and associated compounds, listed as substances whose dumping is restricted. A permit must be obtained to dispose of sediment containing such “restricted” substances. Therefore, the ESIA, which provides much of the information required for the permit, should include detailed marine and sediment studies that aim to:

• Characterise the dredged material to be dumped offshore
• Identify suitable sites for its disposal, taking into consideration:
- The nature of the material to be dumped compared to the nature of the seabed at potential disposal sites
- The water depths, current and wave patterns at disposal sites, which would affect whether the material might be contained, moved around, or potentially washed onshore after dumping
- The benthic flora and fauna that would be disturbed by dumping, and their relevant abundance in the surrounding area
• Model the distribution and movement of sediments in the water column both during dredging activities, and dumping of dredge spoil, to determine the areas to be disturbed and other water users that might be affected

SRK has developed a very good understanding of the obligations imposed by international protocols and the studies required to ensure that permissions and authorisations are expedited. This experience is readily transferable to other coastal waters where the same set of protocols apply, and SRK has recently embarked on similar projects in South America and elsewhere in Africa.

Chris Dalgliesh:
Sharon Jones:

You can download a PDF of the entire
Environmental Process newsletter 

PDF Letter



Our newsletters focus on specific areas of interest to earth resource professionals and clients. Each is available as an Adobe Acrobat PDF file. If you don't already have Adobe's PDF reader, you can download it free.



SRK Worldwide