Remediation Strategy

Remediation strategies for contaminated land (whether soil or groundwater) can vary widely in methods and scope, and these will depend on the specifics of your site, any development and the associated remediation objectives. Adeptus draws on a unique blend of technical and scientific knowledge with a solid understanding of construction methods, to provide pragmatic solutions that where possible, are integral to the development process.

Remediation is generally undertaken where unacceptable risk to human health or the environment has been identified via the formal risk assessment process set out in CLR11. Various technical solutions are available for the achievement of risk reduction and remediation objectives, yet in some cases risk management may be preferable, for instance by simply restricting access to certain areas, introducing barrier layers or altering site layouts.

A remediation strategy is the overarching plan developed to achieve the remediation objectives agreed at the outset, and may involve one or more of the options referred to above. The strategy developed will depend on many factors, such as the type and number of significant contaminant linkages to be addressed, nature of contaminants, and practical constraints such as space, time and budget.

Remediation options appraisal is the process of identifying the individual remediation solutions that can feasibly reduce such risk to acceptable levels, and selecting the preferred option(s) based on site-specific technical, practical and financial criteria, and the views of relevant stakeholders. Where remediation objectives are based on a numerical value, such as contaminant concentration, mass volume or barrier properties, site specific remediation criteria are developed to provide end-points against which remediation can be measured.

Risk based remediation objectives allow resources to be directed appropriately for the reduction of environmental and human health risks to acceptable levels, whilst avoiding excessive time, cost or resource use. The latter is often termed sustainable remediation - a concept which is key to commercial regeneration of brownfield sites, and equally applicable to the clean-up of impacted industrial facilities or other sites.

Since contaminated land risk assessment and remediation are based on the significant contaminant linkage concept, with each consisting of a source, pathway and receptor, remediation options can generally be grouped in three broad categories, as described below.

Source Removal or Reduction

If the source of contamination is removed, or its mass or concentration sufficiently reduced, then the risk can also be considered mitigated. Mass excavation and disposal off-site is often feasible for small sites consisting of Made Ground, and complete removal may not be necessary, for instance where excavating to a sufficient depth to enable introduction of a cover system. However, rising landfill taxes render 'dig and dump' increasingly expensive, there are many limitations on its use.

The regulatory regime has also evolved to simplify permitting requirements for source material being translocated on the same site or moved to another site, under certain circumstances (and with the correct procedures being in place to avoid incurring landfill tax charges from HMRC). Where technically feasible, this kind of approach can avoid disposal to landfill and the resultant use of replacement soil resources, as well as the associated road transport, which are central considerations in achieving sustainable remediation.

More technical and scientific approaches to source-removal involve the introduction of chemical, biological or physical agents to bring about reduction in contaminant mass, concentration or toxicity. Similarly, such agents can be used to stabilise or solidify the soil matrix containing such contaminants, rendering a source effectively inert. If the source of contamination is removed, or its mass or concentration sufficiently reduced, then the risk can also be considered mitigated. Mass excavation and disposal off-site is often feasible for small sites consisting of Made Ground, and complete removal may not be necessary, for instance where excavating to a sufficient depth to enable introduction of a cover system. However, rising landfill taxes render 'dig and dump' increasingly expensive, there are many limitations on its use.

The regulatory regime has also evolved to simplify permitting requirements for source material being translocated on the same site or moved to another site, under certain circumstances (and with the correct procedures being in place to avoid incurring landfill tax charges from HMRC). Where technically feasible, this kind of approach can avoid disposal to landfill and the resultant use of replacement soil resources, as well as the associated road transport, which are central considerations in achieving sustainable remediation.

More technical and scientific approaches to source-removal involve the introduction of chemical, biological or physical agents to bring about reduction in contaminant mass, concentration or toxicity. Similarly, such agents can be used to stabilise or solidify the soil matrix containing such contaminants, rendering a source effectively inert.

Pathway Management

Risk can also be mitigated by management or removal of the pathway(s) by which any receptor is exposed to harm. This may be achieved for instance by the introduction of in/on ground barriers, the manipulation of groundwater flow, or limiting the use of abstracted groundwater. In some cases pathway removal may achieved by relatively simple updates to development proposals or layout.

Receptor Removal

Complete receptor removal is not always feasible without a change of use, or in the case of receptors such as groundwater or sites of ecological significance. It may also be feasible to reduce risk simply by preventing access to an affected area, using physical measures such as fencing, or other methods often referred to as behaviour modification.

Remediation Method Statement

A remediation method statement or implementation plan sets out the how the remediation strategy will be applied, and the details steps to be taken to be taken in order to achieve the agreed remediation objectives. This will often be required via a planning condition, whereby a written plan must be submitted and approved by the local authority before work commences on-site. A well written implementation plan should leave the reader confident in the solution and its proper application.