Following extensive geochemical testing, numerical modelling and a detailed hydrogeological risk assessment, the Environment Agency removed their objections to infilling the quarry, provided it was undertaken in accordance with a Quality Assurance regime with professional full-time supervision by TerraConsult. This was provided throughout the contract and included control of loading at source, chemical testing of the fill placed and supervision of the fill placement. The geotechnical aspects of the design were key to ensuring that post infilling settlement and differential settlement constraints were addressed. Compaction trials were undertaken, and a method specifically developed for the earthworks. Following the infilling settlement, monitoring confirmed the suitability of the site for development with residential housing. The site was subsequently purchased by a national house builder and successfully developed.