Risk v significance

19th March 2014

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Begum Bidik Nash

Experts from CampbellReith compare the risk-based approach used in geoenvironmental assessments with the significance-based approach used in EIAs

Under the national planning policy framework (NPPF), development projects in England that require formal planning consent must undergo an assessment of geoenvironmental conditions regardless of whether the development is likely to need an environmental impact assessment (EIA).

This geoenvironmental assessment is required to ensure that the development is “suitable for its intended use” and does not pose a significant risk to human health or the environment.

The UK takes a risk-based approach to dealing with land contamination. This article takes a look at this approach and outlines how it differs from the “significance” approach used in EIAs.

Geoenvironmental assessments

Geoenvironmental assessments are required under the NPPF. It states that planning policies and decisions should ensure that a site is suitable for its new use “taking account of ground conditions and land instability”. The NPPF makes clear that this includes issues caused by natural hazards or former activities at the site, such as mining, and any pollution arising from previous uses. Proposals for mitigation, including land remediation, and its impacts should also be included. The NPPF also states that after remediation the land “should not be capable of being determined as contaminated land, under Part IIA of the Environmental Protection Act 1990”.

To fulfil these requirements, geoenvironmental issues are assessed using the method detailed in the Environment Agency’s guidance document CLR 11 –Model procedures for the management of land contamination. Other useful guidance includes Defra’s Green leaves III – Guidance for environmental risk assessment and CIRIA’s C552 – Contaminated land risk assessment: a guide to good practice. CIRIA’s book states that risk assessment underpins the appraisal of contaminated land.

The technical geoenvironmental reports required by the NPPF are typically used to inform the EIA and, in particular, the chapter within the environmental statement on ground conditions.


EIA is used to identify and understand the significant environmental consequences of a new development. It identifies the potential impacts of a project, adopts measures to reduce or remove any negative effects, and then re-evaluates the remaining effects.

Key differences

There are a number of differences between the risk based approach used in geoenvironmental assessments and that used in EIAs. The key one however, is a subtle difference in definitions. While geoenvironmental assessments are based upon risk, defined by Defra as: “A combination of the probability (or frequency) and, of occurrence of a defined hazard and the magnitude of the consequences of the occurrence.”

EIAs are underpinned by the assessment of the “significance” of a defined impact. EIAs categorise a development’s environmental impacts as being neutral, minor, moderate or substantial by considering the magnitude of the impact and the sensitivity of the receptor and this allows the relative significance of the effects to be determined on a scale in line with other topics and, ultimately, the significant effects to be identified.

Another issue associated with assessing land contamination is that of how the impact is brought about. Unlike noise and air quality, where the impacts are generally caused by the construction and operation of a development, the impact from contaminated land may already be present as a result of a site’s historic industrial legacy. It is therefore the unusual scenario whereby the baseline conditions are already impacting the environment or presenting a risk to human health and require appropriate mitigation to enable the development to be suitable for use under NPPF. Of course, for industrial facilities, the potential environmental impacts are also a function of their operation and the impacts can be appraised in the normal way.

Another difference that sets land contamination apart is how impacts to human beings are considered. The EIA Directive (2011/92/EU) requires the effects of a project to not only assess impacts to the environment, but also ensure that concerns related to protecting human health are addressed. As such, social impacts are dealt within an all-encompassing socioeconomics chapter within the environmental statement. However, as land contamination is primarily concerned with risks to human health as well as those to the wider environment, these impacts are discussed within the ground conditions chapter instead.

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