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.
Remediation activities in 2015 were mainly at Umbogintwini, as described below. A legacy manufacturing site in Johannesburg was also remediated. Since the waste arising from these projects was not the result of ongoing operations it was excluded from the data reported.
A highlight in terms of GOING GREEN was that the 2015 Mondi Prize for Wetland Stewardship was awarded to AECI’s Paardevlei Properties for its role in successfully rehabilitating a contaminated area at the Group’s former Somerset West site.
Umbogintwini remediation update
Chemical manufacturing activities at this site commenced more than 100 years ago. Global awareness of the environmental impacts associated with chemical waste storage and management only developed much later and, by then, soil and groundwater had been impacted significantly. The progressive reduction of these impacts, coupled with the protection of off-site environments, has been the main driver of AECI’s INNOVATIVE and award-winning remediation programme over more than 20 years.
Remedial activities are governed by the Umbogintwini’s Remediation Strategy (“the Strategy”) and Action Plan which is overseen by the Department of Environmental Affairs and the Department of Water and Sanitation, in terms of the National Environmental Management: Waste Act, No. 58 of 2008, as amended. The prioritisation of remedial activities is risk-based. The Strategy is updated annually to reflect (among others) successfully implemented remedial interventions, the findings of scientific investigations, research into technological advances, legislative requirements, the requirements of authorities and those of interested and affected parties.
Chlorinated hydro-carbons (“CHCs”) are one of the chemical groups that remain persistent in groundwater. CHCs are recognised worldwide as being extremely recalcitrant with respect to remediation. The successful removal of these chemicals from groundwater requires the implementation of INNOVATIVE science and international best practice over a timeframe that could span decades.
Numerous scientific studies, including international reviews, were performed to evaluate the most appropriate remedial approach for CHCs before enhanced in-situ bioremediation (“EISB”) was adopted as the technology of choice. This technology has been implemented through the creation of “biobarrier zones” in the sub-surface, down gradient (in groundwater terms) of the source areas.
The growth of microbes in the biobarrier zones is enhanced through the injection of “food” (in the form of vegetable oil) into the sub-surface. The migrating groundwater passes through these biologically active zones where the dissolved CHC constituents are remediated through microbial activity — the microbes “breathe” the chemicals, thereby facilitating degradation.
The EISB programme commenced in 2007 and has been rolled out progressively in two areas at Umbogintwini. Progress has been such that this biotechnological solution has replaced other more conventional, medium-term remediation initiatives such as the pumping and treatment of groundwater. The large-scale oil injection currently underway is the final step towards the creation of two full-scale, functional biobarriers.
A number of previously contaminated areas at Umbogintwini have already been remediated successfully. Some of these remain under management control and have been incorporated into suitable land use initiatives that include green belt zones and conservation areas, while others have become suitable for industrial re-use.
Although the management of residual impacts due to a long history of chemical manufacturing activities at this historical AECI site is challenging, international and local peer reviews have confirmed that AECI is applying the correct mix of available remediation technologies to progressively reduce its environmental footprint over time.