Phase 1 Desk Studies
The company and its employees have extensive experience of undertaking phase 1 (environmental and historical) desk studies in accordance with guidance as set out in CLR11. 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 preliminary information on other parameters such as radon concentration, vulnerability of watercourses, aquifers and public water supply abstractions. This phase can also include searches for coal workings, petroleum tank searches, and other relevant research areas, such as mineral studies. This data is then collated to assess potential sources, pathways and receptors, culminating in a preliminary conceptual model and risk assessment.
Phase 2 Site Investigation
Based upon our exact understanding of why a client requires investigation work, our engineering consultancy staff hone and scope our investigations to meet their objectives. Before carrying out intrusive investigation we undertake walkover surveys to confirm the sources and receptors (and likely pathways) identified in the Phase 1 study and subsequently adjust and finalise the exploratory hole 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). Decontamination units can be deployed for use on contaminated sites falling under Category RED in contaminated land practises.
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, vulnerability of 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.