Risk Assessment

Since the withdrawal of the ICRCL 59/83 guidance, risk assessment has become central to the investigation of contaminated land. It involves gathering information about a site, through desk studies, walkover surveys and intrusive investigations and, dependent upon the environmental setting and current or proposed use, making an informed judgement on the risk or liability associated with the contamination present and the requirement for measures to mitigate the risks identified.

The significance of the potential risk, to human health or the environment, is determined through a combination of the probability of occurrence and the potential severity of the consequence.

At Terragen the investigation process is undertaken in accordance with BS10175:2001 Investigation of Potentially Contaminated Site – Code of Practice and is broken into various stages as detailed below:-

• Phase 1 Desk Study – Production of a Conceptual Site Model
• Phase 2 Site Investigation – Excavation of exploratory holes and sampling
  o Tier 1 Risk Assessment – Use of generic assessment criteria and basic statistical techniques to interrogate data.
  o Tier 2 Detailed Quantitative Risk Assessment – Use of fate and transport modelling techniques to assess potential risks from identified contaminants to human health and/or controlled waters
• Phase 3 Remediation Methodology – Outline of measures to mitigate the risks identified to human health and controlled waters to acceptable levels
• Phase 4 Remediation Validation – Provides confirmation of the success of the remediation process, required for regulatory “sign-off”

The process detailed above is phased, such that the outcome of each phase will determine the scope of, or in fact need for, the proceeding phase. In many cases regulatory approval is required at the conclusion of each phase prior to proceeding to the next.

All sites and scenarios are different, which as a result means that investigations need to be tailored to our clients specific requirements. Therefore at Terragen we aim to ensure that all aspects of our site investigations not only address the specific requirements of our clients, but also address the demands of the local planning authority and the Environment Agency within the regulatory and planning framework.

An investigation may require part or all of the Phases 1-4 to be undertaken to fully assess and mitigate risks from contamination. If you would like further information on other aspects of the Contaminated Investigation process then please see the following pages. Alternatively if you require additional advice or have a question relating to a specific site please contact us at info@terragenenvironmental.co.uk