The guiding principles underlying AECI’s land remediation activities are the protection of human health and the environment and the use of good science, proven concepts and the best available appropriate technologies. Human health and environmental risk assessments are undertaken and these influence subsequent activities. Stakeholder communication in the remediation process is vital and AECI cooperates with regulatory authorities and shares information with interested and affected parties on a regular basis.
The majority of AECI’s remediation expenditure in 2016 was at Umbogintwini. An innovative programme of enhanced in-situ bioremediation projects, presented in some detail in the 2015 integrated report, continued to show pleasing results.
Extensive engagements with officials from the DEA took place regarding Group sites in the Western Cape, KwaZulu-Natal and Gauteng to confirm that the authorities are in agreement with AECI’s approach to land remediation. Agreement was also reached on the basis for the development of a comprehensive remediation strategy for the Modderfontein site, although the majority of this site remains an active manufacturing hub.
Waste arising from remediation processes is not the result of ongoing operations and, therefore, it is not included in the performance data reported. Some of this waste is classified as hazardous and is disposed of in appropriately licensed facilities. However, other waste is suitable for recycling, and every effort is made to reduce unnecessary disposal of materials that may still serve a useful purpose.
An example of this is ash from historic gasifier operations which is reclaimed by third-parties and used for its calorific content in the manufacture of bricks. From 1974 AECI operated the largest coal-based ammonia plant in the world at Modderfontein. A by-product of the coal gasification process was large quantities of comparatively high calorific value ash. Serious efforts were made to re-use this in a specially designed and built steam boiler, but this proved not to be feasible with the technology available at that time.
As a result, the ash was deposited in a slimes dam at Modderfontein. More than 6 000 000 tonnes had been accumulated by the time the ammonia plant shut down in the late 1990s.
Leaving the ash in place was not an attractive proposition, both because a large area of land is kept out of productive use and because in the long term slimes dams require maintenance and pose potential threats to the environment. This material is now being reclaimed to be used as an energy source in the manufacture of various types of clay bricks, ranging from clay stock to high quality face bricks.