Mitigation - applying best practice

15th October 2013

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RSK Environment's Kitty Hankins examines what constitutes best practice in mitigation and discusses the challenges of applying it to real-life projects

Key sources on best practice mitigation, including John Glasson’s Introduction to environmental impact assessment, suggest that different types of mitigation should be considered as a hierarchy.

First, mitigation measures to avoid significant adverse effects should be considered and, if it is not possible to avoid significant adverse effects, then measures to reduce these effects should be considered.

Compensation for effects, offsite enhancement and/or remediation of effects should only be considered if it is not reasonably possible to avoid or reduce significant effects.

Mitigation implementation

Best practice mitigation is only worthwhile if it is actually implemented. It is therefore vital that mitigation measures are described in sufficient detail that they can be successfully implemented, and that developers make a clear commitment to implementing mitigation measures described in the environmental statement, rather than mitigation being presented as suggestions.

Presenting a schedule of mitigation and/or an environmental management plan are effective ways of allowing the consenting authority to condition mitigation as part of a project’s planning consent and to monitor its implementation.

Mouchel’s EIA Quality Mark article, Practical and effective environmental mitigation, suggests an environmental clerk of works can also be useful to advise on the implementation of mitigation.

It is also crucial that mitigation measures proposed in environmental statements are effective. EIA’s should include the use of proven techniques and the environmental statement should assess the likely effectiveness of the mitigation proposed and any residual impacts remaining.

The effectiveness of mitigation should also be monitored, with alternative proposals put in place in case the mitigation does not work as expected.

Implementing best practice

The challenge of applying best practice to real projects starts with the mitigation hierarchy.

EIA consultants are often contacted by developers after key project decisions have been made. For example, developers may have identified a preferred route or site for their project that impacts a designated site, before involving an EIA practitioner.

This means the environmental statement can only offer mitigation to reduce impacts or compensate for impacts. Jo Treweek and S Thompson (in their 1997 article in The International Journal of Sustainable Development and World Ecology) and David Hill (in IEEM fellows lecture: restoration, reintroduction and translocation) both describe a failure to adequately mitigate impacts on designated sites as a common problem in environmental statements.

EIA consultants should encourage developers to think about mitigation from the project outset as this provides the best chance to apply the mitigation hierarchy and to avoid sensitive sites.

Even if avoiding a sensitive site adds to the cost of construction, it can prevent regulatory delays; reduce the restoration and post-construction monitoring imposed on the developer; and send a positive PR message demonstrating the developer’s commitment to reducing environmental impacts.

Where it is not possible to avoid impacts through rerouting or alternative sites, impacts can be avoided through the timing of works, to avoid peak wintering or breeding periods for birds, for example, or through changes to the project design, such as reducing the height of wind turbines, before compensation or offsite enhancement is considered.

The next challenge is securing commitment and agreement from the developer for the mitigation proposed. Developers often prefer vague language to describe mitigation in environmental statements, such as “mitigation may be implemented where possible”, but good practice dictates that mitigation should be presented as clearly defined commitments.

Presenting mitigation in a schedule in the environmental statement can achieve this, and also helps in monitoring and auditing the project, and to ensure nothing in the environmental statement gets missed during project construction.

It is particularly helpful if the schedule provides specific details on:

  • what the measure is;
  • why it is needed and what it is designed to achieve;
  • when it needs to be implemented;
  • where it needs to be implemented;
  • how it will be implemented; and
  • the person/role or organisation responsible for completing the measure.

Good practice also dictates that mitigation should make use of proven techniques. However, there are not always proven techniques available to mitigate impacts.

A recently consented onshore wind farm project faced objections to potential impacts on bats. A mitigation strategy was developed that involved switching off the turbines around dawn and dusk and monitoring for bat carcasses using specially trained dogs.

This is an unproven technique, but the monitoring proposed will test its effectiveness. If turning off the turbines is proven to reduce or prevent bat mortality, this mitigation could be applied to other wind farm projects in the future.

Therefore, while it is good practice to use proven techniques, sometimes it is appropriate to use innovative mitigation measures that may not be proven, provided adequate monitoring is included. In this way new methods can be tested and added to the range of “proven techniques” available.

This article was written as a contribution to the EIA Quality Mark’s commitment to improving EIA practice.

Kitty Hankins is a consultant at RSK Environment

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