EIA requirements

EIA Regulation 5 (2) requires that: “The EIA must identify, describe and assess in an appropriate manner, in light of each individual case, the direct and indirect significant effects of the Proposed Development on the following factors—

  • population and human health;
  • biodiversity, with particular attention to species and habitats protected under Directive 92/43/EEC and Directive 2009/147/EC;
  • land, soil, water, air and climate;
  • material assets, cultural heritage and the landscape;
  • the interaction between the factors referred to in sub-paragraphs (a) to (d).”

The requirements set out in the EIA Regulations are explained in Planning Inspectorate Advice Notes inter alia:


In due course, the Cambridge WWTW design and proposals for its construction will be developed in enough detail to support a thorough examination of the scheme’s potential environmental impacts and effects.  The Environmental Impact Assessment (EIA) is the process through which this examination is undertaken. Its findings will be presented in a report called an environmental statement (ES), a key document submitted with the Development Consent Application.

Impacts and effects

Two words that are fundamental to EIA are “impacts” and “effects”.  These are subtly different and as they will be encountered frequently on this website and in the EIA over the coming months, it is worth explaining this here.

An environmental impact refers to a change. For example: landtake or demolition, sound or vibration, ground movement, site discharge, impedance to water, emissions to air, visibility, and changes to the transport system.

An environmental effect is the consequence of an impact for the people that experience it or the resources that undergo it. It reflects a value judgment.  Effects on people include inconvenience or reduced health, amenity or wellbeing.  Effects on features refer to the elimination of or depletion in the value or function of an environmental resource or heritage asset.

EIA tends to focus on those environmental impacts that cause adverse effects.  But certain impacts can also cause beneficial effects by enhancing the quality of life or the environment.

Different environmental effects can be experienced or realised at different geographical scales and over different lengths of time.  The EIA will therefore consider not only direct (on-site) effects, but also short range local effects, remote effects and those that extend significantly beyond the project footprint such as climate change.  Additionally, the ES will distinguish effects according to when they are experienced or realised, as well as considering the approximate frequency and/or duration of predicted effects.

Evaluation: determining significance

Depending on the extent or size of the impact (referred to as its magnitude) and sensitivity of the affected resources/receptors to the impact (itself taking account of numerous factors), environmental effects can have different consequences.  The EIA will take these matters into account in assessing the importance of the effect and ascribing it as being significant or not significant. This project defines a significant effect as one that should be considered by the decision makers in granting development consent.

Evaluation criteria are helpful in distinguishing a significant effect from a non-significant effect.  Taking account both of impact magnitude and receptor/resource sensitivity, the different evaluation criteria for each assessment topic will determine effects as being major, moderate or minor.  In general, a major or moderate effect will be deemed significant.

However, used on their own, evaluation criteria can fail to reflect the more subtle and specific sensitivities or tolerances of a local community or environmental resource to a particular impact.  For example a visual impact in certain urban settings may be deemed more acceptable to local people than an equivalent impact in a rural environment. Professional judgement may therefore often be required in concluding significance, resulting for example in some minor effects being deemed significant or some moderate effects being deemed non-significant.

Other factors that can influence the significance of an effect include the duration of an impact and the number of people, resources or receptors affected.

These concepts may be considered part of an impact’s magnitude, but their explicit coverage within EIA can vary between topics. Some topics use additional thresholds for these factors to support the evaluation process. These can be helpful, provided they are broadly consistent both within and between different topics.  It is important that any such additional context is clearly stated when reporting effects.

Cumulative and combined effects

The EIA will consider impacts and effects in the round, taking account of how separate impacts from the construction or operation of the project could cause an overall combined effect. For example noise, traffic and visual impacts at one location exacerbating disturbance for local residents, or several separate interventions in the flood plain together resulting in a significant flood risk. The ES will describe significant combined (intra-project) effects.

The ES will also describe significant cumulative (inter-project) effects, where impacts from unrelated projects are experienced together. These might be additive; for example due to construction traffic from several projects. It may be spatial; for example where a resource such as open space is impinged by more than one development. Or it may be temporal, where a sequence of consecutive developments prolong the overall effect. The identity of other projects that might contribute to a cumulative effect will be agreed during the course of the EIA.