The industrial heritage of the UK has left a legacy of previously developed land across the country. New initiatives, both financial and legislative, are resulting in more and more developments on such sites. To be successful, the impact of the contamination hazard has to be understood and mitigated against beginning with a Contaminated Land Risk Assessment, which is commonly undertaken in a phased approach to ensure thorough assessment and targeted investigation/remediation. The phases of work are generally:
- Site Reconnaissance and Desk Study Assessment;
- Intrusive Investigation – targeting and geo-hazards identified in Stage 1 with suitable investigation methods;
- Remediation – to ensure the pollutant linkage to the development and/or site end user is broken e.g by methods such as removing or the in-situ treatment of contaminated soils;
- Validation – Validation works are carried out to demonstrate that the hazards identified in stages 1 and 2 have been suitably remediated by the works undertaken in Stage 3. Often 3rd Party or Regulator liaison/verification will be required at this stage.
We are experienced in performing tiered risk assessments, using methodologies dictated within published guidance, and using quantitative risk assessment models, to derive site specific remedial targets for a range of receptors. These include health assessments from soil contamination, controlled water risks assessments, and ground gas assessments.
As a result of the assessments we will undertake/contribute to the design, implementation and validation of any mitigation measures or remediation schemes.
Developing Conceptual Models is an essential part of any geo-assessment. It requires a detailed knowledge of the geology, hydrogeology, and the nature of the contaminants. We have the knowledge necessary to produce accurate, defensible Conceptual Models and have done so on a wide variety of sites. These have included mine workings, industrial facilities and at dock land where complicated groundwater regimes are common.
An extensive knowledge of the history and nature of the contaminants is also necessary. ESP has a proven track record on many different sites with a wide variety of contaminants, including hydrocarbons, heavy metals and pesticides.
ESP have also recently been involved in the assessment of landfill materials in an estuary environment, utilising investigation and testing methods to determine the ‘life stage’ of the landfill and the potential effects on the surrounding environment. We use a range of accredited laboratories for sample analysis to ensure accurate and efficient turnaround, all of which is important in developing an accurate Conceptual Model.
Numerical modelling is a valuable tool for generating an accurate representation of the dispersion of contamination across a site. This requires a detailed understanding of the geology and groundwater regime and an in-depth knowledge of a number of different software programs. Deterministic and probabilistic methods are important in developing the understanding of contaminant behaviour and migration pathways in a tiered approach.
At ESP we use a suite of software programs including Surfer, QGIS, CLEA and a number of different Excel based programs including those developed by the Environment Agency and US Government. As each project and site has different requirements, our numerical modelling selections are tailored to suit individual needs and requirements.
A detailed understanding of the site conditions as well as current land and environmental legislation is vital to the carrying out of both qualitative and quantitative risk assessments. Earth Science Partnership provides the skills necessary to delineate sources, pathways and contamination receptors, using Environment Agency and other authoritative guidance.
Risk assessment is often cost effective as in many cases the delineation of contamination, along with understanding the geological conditions, can significantly reduce or eliminate remediation requirements.
Project Example: Geotechnical Engineering, Site Investigation, and Contaminated Land Risk Assessment
ESP have undertaken a site investigation and long term groundwater monitoring in order to assess the risk to controlled waters at Waterloo Industrial Estate, Pembroke Dock. The site, previously developed on a historic landfill, comprises a commercial/light industrial development and lies adjacent to the environmentally sensitive Milford Haven waterway.
ESP have previously carried out investigations at the site and with the most recent investigation primarily comprising the assessment of spatial distribution of groundwater contamination and an appraisal of the viability of natural attenuation as a potential remediation method for the site.
A selected list of example projects can be found on our Projects and Technical page.