The applicant’s own Odour Assessment (Document Ref: 26_00489_OUT) confirms that the approved digester is the principal odour concern affecting the site and is located approximately 755–775 metres from the proposed development (Section 6.0). The same assessment identifies the source as having a large odour potential and describes the likely odour character as “putrid, foul, decayed”, i.e. a highly offensive source rather than a neutral background odour (Table 5.2; IAQM Guidance). It further concludes that, even on its own methodology, there is potential for a “slight adverse” effect at this proposed residential site (Section 6.0).
This is not a finding of “no impact”. It is an admission by the applicant’s own consultant that harm to residential amenity is possible from an approved industrial biological processing use expected to be operational prior to occupation of the proposed dwellings. In planning terms, this is a material consideration and should not be minimised.
The assessment then seeks to downplay this impact through a series of assumptions which are not robust.
Firstly, the conclusion of “negligible effect” relies on mitigation assumptions derived from much older supporting material associated with the digester permission, including a 2009 basic air quality appraisal (Section 6.0). The report itself acknowledges that this earlier assessment is outdated and that guidance and standards have since evolved, meaning the predictions may require revision. Despite this, the housing proposal relies on these historic assumptions to reduce an identified adverse effect to a negligible one. This is not a sound or up-to-date evidential basis.
Secondly, the odour assessment is not based on actual operational data, as the plant has not yet been constructed. The report explicitly confirms that no operational baseline could be assessed and that the conclusions are therefore based on theoretical modelling and meteorological analysis rather than real emissions data (Sections 1.0 and 6.0). This introduces a high degree of uncertainty and should have resulted in a more precautionary approach.
Thirdly, the report relies on meteorological data from Church Lawford Weather Centre, approximately 19 km from the site, and states that odour-conducive wind conditions occur around 10% of the time (Section 6.0). Even on this basis, this equates to a meaningful proportion of the year and cannot reasonably be described as negligible.
The report further attempts to reduce the significance of this impact by suggesting that many odour events would occur at night and would therefore have a reduced effect on residents (Section 6.0). This is not a reasonable or evidence-based conclusion. Night-time is when residents are most sensitive to environmental disturbance, particularly in bedrooms where prolonged exposure occurs. During warmer months, windows are commonly open for ventilation, increasing the likelihood of odour ingress. Odour events at night therefore have a clear potential to disturb sleep and materially affect residential amenity, and cannot be dismissed as having limited impact.
Fourthly, the assessment classifies the pathway between the digester and the site as “ineffective”, largely on the basis of distance and prevailing wind direction (Section 6.0). However, residential receptors are acknowledged to be of high sensitivity (IAQM Guidance), and the source is acknowledged to be highly offensive. In such circumstances, it is not credible to conclude that no mitigation is required for a large residential development.
Fifthly, the assessment fails to consider cumulative impacts. It explicitly states that there are no other significant odour sources requiring consideration (Section 5.0). This is a significant omission. Planning decisions must consider the real environmental context, including cumulative pressures from existing infrastructure and environmental constraints. The assessment’s narrow scope undermines its reliability.
There is also a clear land-use planning concern. The anaerobic digestion / biogas plant is an approved development. If this housing scheme is permitted without a robust and current assessment of odour impacts, it risks creating a foreseeable conflict between future residents and a lawful nearby industrial operation. This runs contrary to the principles of good planning and the need to ensure that new development is appropriate for its location.
The National Planning Policy Framework requires that development provides a high standard of amenity for future occupants and avoids unacceptable levels of pollution (paragraphs 174 and 185). It also reflects the “agent of change” principle, whereby new development must mitigate the impact of existing or approved uses. In this case, the proposed development has not demonstrated that it can do so.
For these reasons, the submitted Odour Assessment (Document Ref: 26_00489_OUT) cannot be relied upon as a robust basis for decision-making. At a minimum, the application should not be approved unless it is supported by a genuinely up-to-date, site-specific and precautionary assessment of the approved digester’s likely impacts, including realistic operational scenarios, current guidance standards, and a proper evaluation of cumulative effects.