Completion of an appropriate site investigation will enable the formulation of a robust Conceptual Site Model, which considers plausible pollutant linkages. Where plausible pathways between actual contaminant sources and potential receptors are identified, remediation will be required, either treatment/removal of the source, or “breakage” of the pathway.
In addition, Lithos also consider the need for ground improvement, and\or the earthworks necessary to create a platform on which development can commence.
Choice of the most appropriate remediation option(s) is influenced by:
(a) The Conceptual Ground Model, including:
- geology, hydrogeology, proximity to watercourses etc;
- volume and distribution of soil requiring remediation;
- nature (eg gravely or clayey) of soil requiring remediation;
- nature of the contaminants – the “mixture”, mobility, volatility, and resistance to degradation.
(b) Classification of the soil for the purposes of disposal to landfill:
- site’s size – area available for remediation activities;
- site’s location – consideration of odour, dust and noise associated with remediation activities;
- redevelopment proposals;
- estimated costs and timescale associated with the proposed remediation technique;
- degree of confidence/certainty in proposed remediation technique;
- views of the Local Authority.
Remediation options for contaminated soils include:
- isolation beneath cover;
- ex-situ bioremediation;
- soil washing;
- solidification or stabilisation;
- recovery of coarse fraction;
- soil vapour extraction;
- excavation & disposal.
And for contaminated groundwaters include:
- pump & treat;
- chemical oxidation;
- Dual-Phase Vacuum Extraction (DVE);
- attenuation monitoring.
Remediation Design & Remediation Strategies
Once a specific development scheme has been decided, we can prepare a Remediation Strategy Report, for submission to the Local Planning Authority.
A Remediation Strategy outlines the remediation objectives necessary to protect environmental receptors, and render a site suitable for the proposed end use.
The Remediation Strategy will include site-specific clean-up criteria for contaminants of concern; the latter such criteria are usually derived by Quantitative Risk Assessment (QRA).
Materials Management Plans
The CL:AIRE Code of Practice (CoP) was introduced in 2008 to provide an alternative and more appropriate means of complying with UK environmental legislation regarding movement and re-use of excavated soils. Previously earthworks and soil import/export were dealt with through complex Waste Management Licensing regulations (now superseded and covered by Environmental Permitting), often via application for exemption.
Lithos, working closely with the appointed earthworks contractor, are able to prepare Materials Management Plans (MMPs).
Lithos are also able to perform the role of Qualified Person (QP), reviewing the MMP and signing a Declaration for submission to CL:AIRE and the Environment Agency. It should be noted that Lithos cannot act as the Qualified Person for projects where we have undertaken the site investigation, and/or prepared the Remediation Strategy. Nor can any company both prepare an MMP and act as QP; it must be one or the other.
As part of their Waste Soils campaign, in December 2016 the Environment Agency audited a MMP produced by Lithos to manage movement of soils between two sites in the north east of England. The EA commented:
"We are happy to report that our findings show there were no non-compliance issues noted. The record keeping was also well-managed, complete and accurate. Duty of care is understood and followed correctly."
Supervision & Verification of Land Remediation
Lithos can supervise remediation works, and on satisfactory completion will prepare a Verification Report to stand as certification that works have been carried out in accordance with the approved Strategy. The Verification Report also provides recommendations with respect to:
- foundation solution(s);
- gas measures;
- placement of soil cover;
- handling and management of excavation arisings generated during construction.