Acer Ecology have a wealth of experience in Environmental Impact Assessments (EIA). We can prepare Ecology Chapters for inclusion within a larger Environmental Statement (ES), or produce stand-alone Ecological Impact Assessments (EcIA). Read on to find out what we can offer.

Ecological Impact Assessments

What is an Ecological Impact Assessment and Why is it Required?

According to CIEEM, the chartered body that oversees the ecology sector, EcIA is “a process of identifying, quantifying and evaluating potential effects of development-related or other proposed actions on habitats, species and ecosystems”.

An EcIA is not specifically a statutory requirement, however, it is often included as part of a wider EIA which are required for certain types of developments when certain thresholds are met. The Town and Country Planning (Environmental Impact Assessment) Regulations 2017 underpin the legislation. Schedules 1 and 2 list the types of developments and thresholds which require a full EIA. Examples include, airports, quarries and pipelines.

Even if a full EIA is not required, an EcIA may still help to demonstrate how a development can comply with planning policy and legislation. There are several stages to an EcIA. These are outlined below:


The first stage of an EcIA is to undertake a scoping exercise. Scoping identifies the baseline ecological conditions on a site, considers the projects zone of influence and likely impacts. Consultation is often sought from relevant statutory agencies which ensures their agreement with the proposed survey methodologies and helps to identify the key ecological issues which will be addressed during the process.

For smaller projects where low levels of impacts are likely, the survey often takes the form of a Preliminary Ecological Appraisal. This stage will identify a broad range of issues relevant to the project which will go on to inform the latter stages of the process. This usually involves a site visit and a desk study. Factors to consider could include: site ecology, habitats on and off-site, licencing restrictions, identifying stakeholders and sources of data and identifying future survey work that may be required.

Impact Assessment

Once the baseline condition of the site is established, the need for any additional site-specific ecology surveys will be understood. More detailed surveys are often required for bats, great crested newts, reptiles, dormice, badgers and water voles. These more targeted, species specific surveys enable the ecologists to get a better understanding of which species and habitats are present on site and enables an evaluation to be made of the sites nature conservation value. Ecology surveys are often seasonally constrained. It is therefore vital for developers to plan ahead to avoid delays to projects.

An impact assessment can then be made which looks at how the development may affect important ecological features (both positively and negatively). Examples of common impacts are changes to or loss of habitat and disturbance through construction practices. The impact assessment should consider the full life-cycle of a project from construction through to decommission. The impact assessment considers:

  • the extent, magnitude, duration, reversibility, timing and frequency of potential impacts;
  • cumulative impacts/effects; and
  • impacts in the absence of the proposed mitigation.

The EcIA process should be iterative, meaning that the process and proposed development should be amended and updated once survey results are understood or if new information comes to light. At the impact assessment stage, this could mean that the survey scope is updated and further survey work undertaken.

Avoidance, Mitigation, Compensation and Enhancement

This stage is based on the mitigation hierarchy; a priority system developed to reduce harm through the four steps outlined below. Often this is a legal requirement, for example, complying with protected species legislation. An example of how this process might work for bats can be found here.

Avoidance – This is the best option in terms of avoiding impacts but not always possible. It involves changing the development proposals to avoid the impacts altogether. For example, moving the development to a different site or re-locating parts of the development to less sensitive areas within the same site. This could also involve changes to working methods or the timing of works.

Mitigation – The second best option. Mitigation measures are put in place to help avoid or minimise the impacts. This can include changes to the design of a project, for example improving existing bat roost provision in a building.

Compensation – Where residual impacts occur despite the avoidance and mitigation measures already undertaken, compensation should be included in the project design to offset these residual impacts. For example, installing new bat roost features on a new building to compensate for those lost through development works.

Enhancement – This final stage of the mitigation hierarchy seeks to provide net benefits to biodiversity as a result of the development, beyond the three previous elements. This could include additional planting or enhancements of the existing on-site habitats to improve them for wildlife.

Monitoring and Management

Often overlooked, monitoring is a crucial part of the EcIA process. Provision should be made to ensure that mitigation, compensation and enhancement measures are enacted appropriately and continue to be affective in perpetuity. A management plan may be useful to ensure that the mitigation strategy is correctly executed and monitored.

Environmental Statement

The final stage of the EcIA process is to produce an Environmental Statement. This report must set out the process that was followed, explain and justify the methods used, detail the results gathered, justify the impact assessment and set out the proposed mitigation strategy. It should highlight any legal or policy issues and acknowledge any missing data or omissions. This document will enable the local authority to reach an informed decision and grant planning consent.

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