In-situ thermal remediation application in South Africa: a case study incorporating sustainable remediation principles

This paper presents a case study of the first instance in South Africa where In-Situ Thermal Remediation (ISTR) was undertaken. The project, completed during 2020 and 2021, is located in Cape Town. The 'Site' is a former printing facility located in a multi-storey building adjacent to an upgradient service station. Petroleum hydrocarbon impacts, identified in subsurface soil and groundwater, originated from leaking underground fuel storage tanks at this service station. Following a sustainability-based options appraisal, ISTR with steam used as the heating source was selected as the most appropriate remedial technology. Based on Environmental Resources Management (ERM's) international and local expertise, this solution was implemented after due consideration of the site's geological characteristics, the properties of the contaminants of concern, and the client's goals of rapidly achieving a risk-based remediation solution. This solution was enhanced by the identification and incorporation, where feasible, of Sustainable Management Practices (SMPs) in the system design and operational phases. Particular focus was placed on resource consumption and the use of alternative power sources, such as reduction of water and energy and use of biofuel. Other SMPs incorporated into the systems operational phase included temperature tracking to optimise steam usage, which have been successfully applied by ERM at previously completed ISTR sites in other countries. Key lessons learnt from the ISTR application at this Site were that the energy source and use, combined with optimization of water consumption, could be more widely applied to improve the sustainability of ISTR, not only in South Africa, but also other sites worldwide.