Summary During site works, at the former landfill site at Ffos-Y-Fran, soils containing leachable mercury above site specific criteria were encountered. As part of the remediation strategy, mercury contaminated material was to be treated by means of stabilisation/solidification (S/S) processes. In accordance with EA guidance, VertaseFLI have designed and engineered a treatment solution that targets and chemically stabilises the leachable mercury.
Initial Development
Initial development began with laboratory phase trials. S/S mix design development was conducted in the VertaseFLI laboratory, during which differing ratios of various binders and additives were combined with the mercury impacted material. Mixing equipment was utilised in such a manner to emulate the on-site mixing process. This was to install confidence during the final decision process, that the mix design chosen would be likely to perform well at an on-site scale.
Testing Treated material was allowed to cure and then subjected to in-house tank tests (in accordance with EN NEN 7375:2004) and strength tests. Samples were then sent to an independent MCERTs accredited laboratory for NRA leachate procedures and chemical analyses.
Results
The results of the laboratory phase trial established the most suitable mix design, where the specified ratio of S/S binder was mixed with the contaminated soil, a chemically stabilised material was produced that did not leach and was compliant with the site specific criteria.
Health & Safety
Throughout the laboratory research and development process, stringent health and safety regulations were followed, including the wearing of PPE at all times and environmental monitoring. | 
