ENVIRONMENTAL IMPACT OF DESALINATION PLANT RECEIVES SPECIAL ATTENTION
In response to concerns that have been expressed about the possible environmental impact of the brine that will be discharged from the seawater desalination plant at Voorbaai into the sea, the Mossel Bay Municipality says that careful consideration has been given to the present proposed location of the brine outlet 460 metres from the beach under the sea.
The desalination plant is being built at a cost of R210 million as a drought emergency project and is scheduled to produce five million litres of potable water a day from early December 2010 onwards. It is scheduled to reach its full production capacity of 15 megalitres of water a day early in 2011. The initial production will go to PetroSA, which is contributing R80 million to the cost of the plant. The balance will be available to the Municipality.
The Municipality says that based on research and current knowledge, the planned position of the brine diffuser is regarded as correct. However, the situation will be monitored carefully when the pipeline is in operation. Even though it will be costly, consideration will be given to extending the pipeline further out to sea if this proves to be necessary to protect the environment.
The Municipality has also considered a beach-based discharge option but this proved to be prohibitively expensive and not meeting the urgency requirements of the desalination project.
A commercial salt production venture was considered, but this did not prove to be viable as the construction and operation of such as facility would be extensive and the cost too high to make it competitive in the market. It was estimated that an area of approximately 214 ha in size would be required for the construction of evaporation ponds alone. As there is no suitable and large enough area close enough to the desalination plant, land would have had to be acquired some distance away and the brine pumped to the site.
Given the volume of brine to be disposed of, the current option proved to be the only realistic option in the case of the Mossel Bay plant.
The urgency of the desalination project required that the environmental impact assessment of the project is carried out in parallel with the construction of the plant instead of prior to project commencement, but this is being done both legally and in ongoing consultation with the authorities concerned.
When the project was announced, the Municipal Manager, Dr Michele Gratz, gave an undertaking that measures would be put in place to ensure that the overall impact of this emergency water project on the environment is limited to the absolute minimum.
“Mossel Bay’s beaches and the sea are very important aspects of its attractiveness to tourists. Tourism in turn is one of the mainstays of the local economy. While the possibility of running out of potable water is possibly the biggest threat ever to have faced the local economy, we will do our utmost to ensure that the environment receives maximum protection in the process to supplement Mossel Bay’s water supply and to ensure that the economy is not harmed,” said Dr Gratz.
It is envisaged that the desalination plant will be mothballed should the surface water situation normalise again and that the plant will in future only be used during emergency situations or when it is needed during peak water consumption periods.