Shifting builds: project delays and the validity of EIA

21st July 2022


When a construction project is delayed, are the environmental impact assessment’s findings still valid? Ellen Smith reports

A consultant carrying out a construction programme environmental impact assessment (EIA) under the Town and Country Planning (EIA) Regulations 2017 must consider the intensity and type of construction activity in order to assess construction effects, and the programme’s completion year in order to assess operational effects. EIAs often consider construction programmes provided by applicants before contractors have been appointed, so are subject to change. However, consultants should assume that most planning applications have a three-to-five-year implementation period, and this should be considered as a minimum in the construction programme.

If there are unknowns in the construction programme, assumptions should be made clear in the environmental statement (ES). Assumptions in the construction programme should aim to provide a reasonable worst case – for example, assuming the nearest potential location of construction plant in proximity to surrounding receptors, and the overlapping of construction activities. While programming for the works may be subject to modification, there has usually been sufficient planning to enable the likely significant environmental effects to be identified and assessed.

When an applicant needs to seek planning permission to change a scheme’s design or phasing, a change in construction programme can be addressed through further environmental information, such as an ES addendum. This could require the assessment of a further interim scenario, should there be a significant delay in delivering part of the proposed development, resulting in part-occupation.

Otherwise, in terms of construction traffic it could be considered that the original dates in the ES present a worst-case assessment for air quality, noise and traffic, as the UK vehicle fleet is projected to improve. Other environmental topics, such as wind, daylight and sunlight, flood risk and ecology are unlikely to be affected by a change in construction programme – unless there is a significant change in phasing, in which case temporary mitigation measures may be required (such as temporary screening if there are wind safety concerns).

Cumulative concerns

One issue with a change in construction programme is the assessment of cumulative effects. A proposed development will not cumulatively interact with other identified cumulative developments during construction if a proposed development or cumulative scheme is delayed.

To provide a worst-case assessment, and where information on the construction programmes of other developments is unavailable, reasonable assumptions should be set out in the ES, such as the extent to which the cumulative schemes would have overlapping construction programmes.

Any new schemes gaining consent following permission for the proposed development – and not previously identified in the EIA as coming forward – should be assumed to have assessed the proposed development in their own cumulative assessments.

So a change in construction programme can be tricky for EIA, particularly when it comes to the cumulative assessment. The consultant should take care to set out the reasonable assumptions made in the assessments, such as the assumption that the cumulative schemes would have their own construction environmental management plans or construction logistics plans in place. Limitations, such as a lack of available information on a construction programme, should also be reported in the ES.

EIAs cannot consider every outcome, but including clear assumptions and limitations allows the appropriate identification of likely significant effects. Whether an EIA is valid when the original construction date has changed should be decided on a case-by-case basis.

Ellen Smith, PIEMA is principal EIA consultant at Waterman Infrastructure & Environmental.

Image credit | Shutterstock

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