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 Development Industry Code of Practice (The Definition of Waste, v2, March 2011; DoWCoP) was originally introduced in 2008 to “help organisations involved in the development of land and its remediation, increasing the sustainability of their methods and approaches”. It provides an alternative and more appropriate means of complying with UK environmental legislation - previously earthworks and soil import/export would have had to be dealt with through complex Waste Management Licensing regulations (now superseded and covered by Environmental Permitting), often via application for exemption.
The DoWCoP sets out good practice for the development industry to use when assessing on a site specific basis whether excavated materials should be classified as waste or not. The Environment Agency (EA) take account of the DoWCoP when deciding whether to regulate the materials as waste. If materials are dealt with in accordance with the DoWCoP, the EA are unlikely to consider materials to be waste if they are used for the purpose of land development.
The DoWCoP requires a Materials Management Plan (MMP) to be prepared in advance of the works, which is then reviewed by an independent CL:AIRE-registered Qualified Person (QP) who submits an online declaration to CL:AIRE once they are satisfied with the documentation. Each time a new source of material for import is identified the MMP should be revised, reviewed again by the QP and a new declaration submitted to CL:AIRE. Materials should not be re-used on site, or imported, until the relevant declaration receipt has been received from CL:AIRE.
Anyone who is found to have knowingly caused or permitted the disposal of waste at an unauthorised site would then become liable to pay landfill tax at the standard rate (£94.15/tonne from 1st April 2020). HMRC can also impose an additional penalty of up to 100% of the tax due.
Lithos, working closely with the appointed earthworks contractor, are able to prepare the necessary MMP. Lithos are also able to perform the role of QP, although it should be noted that Lithos cannot act as the QP for projects where we have undertaken the site investigation, and/or prepared the Remediation Strategy.
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.