This project will commission a Rapid Evidence Assessment (REA) of UK specific resources to identify relevant considerations for what is meant by “disproportionately costly”. Disproportionately costly is one element of assessing if all necessary and reasonable measures have been taken to prevent inputs of pollutants into groundwater for remediation and re-deposit of contaminated materials as a groundwater activity (Schedule 22 Environmental Permitting Regulations 2016). Guidance exists on how to carry out cost benefit analysis for the detailed evaluation of remediation options to manage the risks from land contamination. There is no guidance on how to carry out cost benefit analysis for the purposes of evaluating disproportionately costly. This REA will be used to develop guidance on how to carry out cost benefit analysis for the purposes of evaluating disproportionately costly.