EIA and the design of onshore wind farms

6th September 2012

Related Topics

Related tags

  • Generation ,
  • Renewable ,
  • Stakeholder engagement ,
  • Natural resources



Andrew Mitchell of RPS Group outlines how constraints analysis and design evolution in environmental impact assessment (EIA) can ensure onshore wind developments are designed sensitively

Without sensitive design, onshore wind farms can have the potential to result in significant environmental effects. One function of EIA is to inform the design and layout such that, where possible, adverse environmental effects are avoided or reduced. It is, therefore, a key role of the EIA practitioner to provide advice that seeks to avoid significant adverse effects at an early stage.

At the outset of a project, it is usual for a developer to identify preferred parameters in terms of numbers of turbines or maximum rated output – as such factors can be important to the financial viability of a wind farm site. However, specific client requirements for the positioning and spacing of turbines are uncommon.

The EIA process can usefully focus on identifying environmental constraints to inform the design evolution process. Through EIA it is possible to ensure the turbine layout is sensitive to the specific site, avoiding significant environmental effects as far as practicable, and incorporating opportunities for enhancement.

A range of factors influence the number of turbines suitable for a particular site and where they should be located, including technical requirements for spacing to ensure efficiency. Such factors may include:

  • The presence of designated sites

    Where possible, turbines should avoid locations within designated sites. In some cases, it may be advisable to avoid locations adjacent or close to designated sites, for example where turbines would have a significant effect on views from nearby protected landscapes.

  • Residential properties

    There is no absolute buffer for residential properties but the findings of the noise assessment, visual amenity and shadow flicker should be considerations in turbine siting.

  • Views

    A zone of theoretical visibility model and wirelines should be used to consider turbine arrangement and height to minimise visibility from sensitive receptors. Use of such tools at the siting stage can allow realignment of turbines to reduce undesired effects such as turbine clustering and blade overlap.

  • Habitats and species

    The results of ecological surveys should inform turbine siting such that priority habitats, migration routes and features supporting bats are avoided. A buffer should be provided to woodland or bat roosts.

  • Peat

    Where present, peat can be a significant consideration. A robust approach to surveying and turbine siting will be required to meet the requirements of statutory consultees. Areas of significant peat resource should be avoided where possible.

  • Water resources

    Watercourses should be avoided, with a buffer implemented, where feasible to avoid pollution. Groundwater resources should also be considered.

  • Public rights of way

    Rights of way can be an important factor at sites intersected by such routes. Minimum and preferred buffers are published for bridleways.

  • Telecommunications and radar

    The location of airports and radar systems should be considered at an early stage, together with microwave fixed links and scanning telemetry.

  • Known utilities and roads

    An appropriate offset buffer from the alignment of utilities and roads may be applied to protect existing infrastructure from physical interference and take into account the theoretical topple-distance of wind turbines.

A design workshop is a good way to consider the input from all relevant topics and to reach consensus on the most appropriate layout. The input of statutory and other consultees may be necessary and valuable, depending on the site and its particular characteristics. Civil engineering design work to confirm both viability and environmental effects is worth considering at an early stage.

Once a layout is selected, work on assessing the identified project can commence. However, it is important to recognise that the design and mitigation process should be ongoing and iterative. Where technical specialists provide feedback regarding a likely effect and measures that could address this, consideration should be given to adoption of such measures as part of the project.

The use of an iterative, site-specific and constraints-led design approach will ensure that effects are avoided where reasonably possible to do so.

The measures adopted as part of the project and the iterative design process should be clearly set out in the nvironmental statement to ensure that the process is clearly demonstrated to decision makers.

Such sensitive design and assessment of a project incorporating measures to avoid and minimise effects will not only provide the most environmentally appropriate design for the site but will also provide the most robust environmental statement, with the best chance of successful passage through the planning system.

Only through completing this process from an early stage and clearly reporting it in the environmental statement can a project truly claim to be sensitively designed and appropriately assessed.

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

Andrew Mitchell is an associate director at RPS Group


Subscribe to IEMA's newsletters to receive timely articles, expert opinions, event announcements, and much more, directly in your inbox.

Transform articles

New guidance maps out journey to digital environmental assessment

IEMA’s Impact Assessment Network is delighted to have published A Roadmap to Digital Environmental Assessment.

2nd April 2024

Read more

Lisa Pool on how IEMA is shaping a sustainable future with impact assessment

27th November 2023

Read more

IEMA responded in September to the UK government’s consultation on the details of the operational reforms it is looking to make to the Nationally Significant Infrastructure Projects (NSIP) consenting process as put forward in the NSIP reform action plan (February 2023).

24th November 2023

Read more

Members of IEMA’s Impact Assessment Network Steering Group have published the 17th edition of the Impact Assessment Outlook Journal, which provides a series of thought pieces on the policy and practice of habitats regulations assessment (HRA).

26th September 2023

Read more

In July, we published the long-awaited update and replacement of one of IEMA’s first published impact assessment guidance documents from 1993, Guidelines for the Environmental Assessment of Road Traffic.

1st August 2023

Read more

Are we losing sight of its intended purpose and what does the future hold for EIA? Jo Beech, Tiziana Bartolini and Jessamy Funnell report.

15th June 2023

Read more

Luke Barrows and Alfie Byron-Grange look at the barriers to adoption of digital environmental impacts assessments

1st June 2023

Read more

Susan Evans and Helen North consider how Environmental Statements can be more accessible and understandable

1st June 2023

Read more

Media enquires

Looking for an expert to speak at an event or comment on an item in the news?

Find an expert

IEMA Cookie Notice

Clicking the ‘Accept all’ button means you are accepting analytics and third-party cookies. Our website uses necessary cookies which are required in order to make our website work. In addition to these, we use analytics and third-party cookies to optimise site functionality and give you the best possible experience. To control which cookies are set, click ‘Settings’. To learn more about cookies, how we use them on our website and how to change your cookie settings please view our cookie policy.

Manage cookie settings

Our use of cookies

You can learn more detailed information in our cookie policy.

Some cookies are essential, but non-essential cookies help us to improve the experience on our site by providing insights into how the site is being used. To maintain privacy management, this relies on cookie identifiers. Resetting or deleting your browser cookies will reset these preferences.

Essential cookies

These are cookies that are required for the operation of our website. They include, for example, cookies that enable you to log into secure areas of our website.

Analytics cookies

These cookies allow us to recognise and count the number of visitors to our website and to see how visitors move around our website when they are using it. This helps us to improve the way our website works.

Advertising cookies

These cookies allow us to tailor advertising to you based on your interests. If you do not accept these cookies, you will still see adverts, but these will be more generic.

Save and close