The interpretative report detailing the site investigation and associated risk assessments will, where necessary, include recommendations for remedial actions. These recommendations will be reviewed by the regulators involved in the project, which will typically include the Environment Agency, the local planning authority and any warrantors for the scheme.
When the requirements for any further work or amendments to the recommendations have been agreed, it is routine to formalise the remedial process in a remediation method statement (RMS). This document details the measures required to make the site suitable for its proposed end use, including any monitoring and validation works.
The RMS will list the documents required to be collated such that at the end of the process there is sufficient evidence to discharge the relevant planning conditions.
The RMS can be used to convey the particular requirements to third parties like ground workers, to ensure all parties are working to the same specification. The RMS will need to be issued to the regulatory authorities to obtain their official approval prior to commencement of any remedial works.
The remediation strategy will depend on the ground conditions, the material or chemical characteristics of the contaminants, and the development proposals. The range of remedial options may include:
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Bunding and capping
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In-ground barriers
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Stabilisation and solidification
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Soil washing and air sparging
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Pumping and treatment of contaminated water
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Vacuum extraction of vapours
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Bio-remediation (in-situ and ex-situ)
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Excavation and replacement (‘dig and dump’)
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Segregation and screening of materials
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Methods of ground gas ingress prevention
Historically ‘dig and dump’ was the typical remediation strategy employed to remove contaminated soils off site. However, given the unsustainable nature of this approach and the costs for disposal to landfill, this method is typically seen as the final resort. The export of site soils and import of replacement soils have both cost and environmental impacts. It is preferable and more cost effective to develop a strategy which minimises export and import of soils, and maximises re-use of site-won materials.