Contaminated Land
Redevelopment on previously developed land or brownfield sites can have many benefits but can also present a number of problems. Contaminated soil and or groundwater resulting from historic site usage, can pose a serious threat to human health and the environment if not adequately addressed prior to the commencement of construction. Similarly, the commencement of works prior to the establishment of site conditions could have serious financial repercussions.
Should you wish to carry out a contaminated land risk assessment to supplement a planning application submission, to address a query from a regulatory body or to conduct due diligence on a site prior to purchase, Hydrec Environmental Consulting can offer a comprehensive list of services.
In order to find the most cost effective and sustainable solution for each site, we typically adapt the following staged process:
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Phase 1 - Preliminary Risk Assessment (PRA). In line with international guidance, contaminated land risk assessments should start with a PRA. A desktop study and initial site walkover allows for the development of a preliminary Conceptual Site Model (CSM) which aims to identify any existing Source-Pathway-Receptor (S-P-R) linkages. Should any complete pollutant linkages be identified or uncertainties be uncovered, the risk assessment needs to progress to a Phase 2 site investigation.
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Phase 2 - Generic Quantitative Risk Assessment (GQRA). Intrusive site investigation may involve the installation and logging of trial pits and monitoring boreholes in accordance with BS5930 & BS10175, collection of soil, groundwater and surface water samples, soil vapor analysis and ground gas monitoring. The information obtained from these investigations is then assessed against the relevant generic assessment criteria (GAC). If a Phase 2 GQRA identifies unacceptable pollutant linkages in may be recommended to undertake a Detailed Quantitative Risk Assessment (DQRA).
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Phase 2 - Detailed Quantitative Risk Assessment (DQRA). While a GQRA may indicate a risk to human health or the wider environment, a DQRA takes further account of site specific information to ascertain if any such risks are significant. Additional works such as more advanced laboratory analysis, hydraulic testing and detailed modelling (e.g. contaminant fate and transport modelling) using various software packages maybe required. Where a DQRA establishes that an unacceptable risk is present, site remediation is required.
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Phase 3 - Remediation & Verification. If the risk assessment shows that remedial measures are required to protect human health and / or the environment, Hydrec Environmental Consulting can prepare a contamination remediation strategy / remedial action plan. Remedial measures will commonly include the delineation, excavation and removal of the contaminated soils (see Soil Waste Classification), capping measures or in-situ chemical / physical treatment. We can also provide, the necessary validation monitoring that can be required during and after remedial works.