Wind farms and their effects on groundwater: guidance for planning authorities and developers

This guidance helps developers identify and mitigate against potential impacts on groundwater when building and operating onshore wind farms. It helps to inform those producing Environmental Impact Assessments in support of planning applications for proposed on-shore wind farm developments.

This advice also offers guidance to local planning authorities considering the associated potential environmental impacts of onshore wind farm applications.

The guidance covers the main areas and issues to be considered when assessing the potential impact on groundwater and tells you which permissions you will need from us.

Impact a wind farm can have on groundwater

Foundations, borrow pits and infrastructure such as roads, tracks and trenches can disrupt groundwater flow reducing the amount of water flowing to nearby watercourses or water supplies. Their construction also removes the protective layers of soil and subsoil making the groundwater below more vulnerable to pollution from leaks or spills from vehicles or equipment used to construct them. It also makes the groundwater vulnerable to leaks and spills from the turbines and other site infrastructure during operation.

Many wind farms now include battery storage facilities which can pose a significant risk of pollution from fires and losses of contaminated firewater into the environment. ficant risk of pollution from fires and losses of contaminated firewater into the environment. Firewater would be a major source of hazardous chemicals.

Information we expect in a wind farm Environmental Impact Assessment

Within a wind farm Environmental Impact Assessment (EIA) we expect the following to be provided:

Detail of the development including the location of turbines and their foundations, borrow pits, roads, tracks, cuttings, hardstanding, laydown area, compounds, cable trenches, pipe lines, borrow pits, any buildings including substations and battery energy storage systems and solar panels.
Detail of the baseline conditions of the site, obtained from desk study and a field survey.
Identification of receptors that could be affected by the wind farm.
Identification of potential impacts to groundwater from the development during its construction, operation and decommissioning, and assessment of the significant of that impact. This should also include assessing the risks to the environment if the intention is to leave infrastructure, notably buried infrastructure such as cabling, in perpetuity, at the site post decommissioning.
Evidence of appropriate incorporation of mitigation buffer zones in the layout design.
Proposed mitigation measures required.

Collecting data on baseline conditions

It is important to establish local conditions prior to development, termed the baseline conditions. This information can be used to influence the design and construction of the wind farm to reduce risks to the environment during construction and operation.

Baseline conditions for groundwater include:

site geology
aquifer designation and groundwater vulnerability status
depth to groundwater
presence of any groundwater source protection zones
a water features survey (to include a field survey) to identify boreholes, wells, springs, watercourses, ponds, lakes and wetland areas in the surrounding area
the quality of groundwater and identifying if this could be contaminated due to historic land uses

Using mitigation buffer zones

To reduce the risk of the wind farm development having a negative effect on the water environment the use of mitigation buffer zones should influence the layout design. Should elements of the development (tracks, turbine foundations, borrow pits, compounds) be located within the buffer zones then further assessment (such as establishing the potential zone of contribution to the water feature) would be expected within the Environment Impact Assessment to justify the expected impact significance. These mitigation buffer zones are:

10 metres away from rivers, streams, lakes, ponds and ditches
50 metres from a spring, well, borehole or watercourse which isn’t used for drinking water
250 metres from a spring, well, borehole or watercourse used for drinking water
250 metres from a designated wetland

Other permissions you might need

You will need an abstraction licence if you abstract more than 20,000 litres per day of groundwater, for example to dewater any turbine foundations or borrow pits that you construct. Find out if you need a licence for dewatering a mine, a quarry or for a civil engineering project.

Any discharges to ground as part of the construction, operation or decommissioning of the wind farm will need an environmental permit. Apply for a permit to discharge trade or mixed effluent.

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