Contaminated Site Surveys
Phase 1 Desk Studies
The company has extensive experience of undertaking phase 1 (environmental and historical) desk studies. These utilise high-quality site-centred Ordnance Survey historical mapping from the late nineteenth century to the present day, and comprehensive environmental database searches. This study determines if the site and surrounding area could have been subject to potentially contaminative use (thus creating potential liabilities) and gives information on other aspects such as radon, watercourses, aquifers and public water supply abstractions. This phase can also include coal mining searches, petroleum tank searches, and other searches such as chalk cavities/mining.
This data is then drawn together to assess potential sources, pathways and receptors, culminating in a preliminary conceptual model and risk assessment.
Phase 2 Site Investigations
Based upon our exact understanding of why a client requires investigation work, our engineering consultancy staff design our investigations to meet their objectives. Before carrying out intrusive investigation we undertake walkover surveys to confirm the sources and receptors (and pathways) identified in the Phase 1 study and then finalise the holes locations accordingly.
Environmental site investigation often utilises the low-disturbance technique of dynamic sampling, as well as excavator-dug trial pits and cable percussion boreholes. Standpipes are often installed for the monitoring and sampling of groundwater and soil gases by our site technicians. On site monitoring can also include in-situ monitoring for water quality, as well as volatile vapours (e.g. petroleum hydrocarbons). We have in-house laboratory testing capabilities for most contaminants in soil and water.
We have investigated sites with varied historical uses including petrol stations, factories, abattoirs, landfills, timber treatment works, scrap yards and foundries. The proposed developments are again varied, with the most sensitive land use generally being residential.
At this phase we provide clients with interpretive reports that assess and advise on the risks to human health, groundwater and surface water resources, buried concrete & services, etc, and such work involves a final conceptual model and risk assessment. If significant risks to water resources are identified, then we can undertake a Detailed Quantitative Risk Assessment (DQRA)(referred to as an RTM, formerly P20). Our interpretive reports also give guidance on the classification of soils for off-site disposal (i.e. Initial Waste Characterisation & WAC tests), as well as any geotechnical aspects such as foundations and retaining walls.
Phase 3 Remediation & Validation Work (plus Consultancy Work)
We have extensive consultancy experience in the redevelopment of brownfield land and the assessment of risk to human health and groundwater. We can assist throughout the development stage with the design, supervision and validation/verification of the remediation process, including the required reporting. We also routinely undertake liaison with local authorities, the Environment Agency (EA) and the National House-Building Council (NHBC) during investigation and remediation and have extensive experience in this area. Qualitative and quantitative risk assessments can be undertaken to ensure that remediation projects address all the issues that may give cause for concern.