Towards a Minerals Local Plan for Derbyshire and Derby

Towards a Strategy for Cumulative Impacts


1       Introduction

1.1    Origins and legislation

The need to take account of the potential adverse impacts of development proposals as well as the benefits of those developments has been at the heart of the modern planning system. The concept of cumulative impacts has also been a recognized element of the planning system for a long time but the need to take account of such impacts was only formally enacted by legislation arising from EC Directive 85/337/EEC (as amended by 11/99/EC) which introduced Environmental Impact Assessment (EIA) regulations. In the UK the relevant legislation was the Town and Country Planning (Environmental Impact Assessment) (England and Wales) Regulations 1999, (notably Schedule 3). The need to take account of the cumulative effects of multiple impacts from individual sites and/or a number of sites in a locality is also included in current Government policy in the National Planning Policy Framework (paragraph 143).


1.2    What are cumulative impacts?

Cumulative impacts are those which are caused by the combined effects of one action, or of several actions or developments at the same time or from a succession of actions or developments over time. It is recognized that cumulative impacts can be beneficial as well as adverse. The assessment of all development proposals requires that account be taken of both benefits and disbenefits and the ultimate decision often rests on the balance between these aspects. Reflecting the messages that you have previously made, this consultation focuses on adverse impacts. For this aspect, the critical issue is the point where the adverse impacts of developments combine to result in a significant adverse impact over and above individual impacts.

Cumulative impacts can be defined in many different ways depending on the circumstances. In generic terms, it can be defined as “impacts that result from incremental changes caused by other past, present or reasonably foreseeable actions together with the project.”[1]

An alternative definition is “the net result of environmental impact from a number of projects and activities.”[2]


A further definition with direct relevance to Derbyshire and Derby and the local minerals and waste industries is that cited in a practice guide developed in response to the issues generated by the Australian mining industry. It states that: “Cumulative impacts are the successive, incremental and combined impacts of one, or more, actions on society, the economy and the environment. Cumulative impacts can result from the aggregation and interaction of impacts on a receptor and may be the product of past, present or future activities. Cumulative impacts can be both positive and negative and can vary in intensity as well as spatial and temporal extent. Cumulative impacts may interact such that they trigger or are associated with other impacts. They may aggregate linearly, exponentially or reach ‘tipping points’ after which major changes in environmental, social and economic systems may follow.[3]


This definition is relevant to the local situation for several reasons. It extends the range of impacts beyond those on the environment to include impacts on society and the economy. It recognises the impacts on people and areas and places importance on those people who have or are experiencing the impacts. It recognises that an impact can affect a wider area due to the linkages with other activities and, importantly, it recognises the role of tipping points or thresholds in the assessment of cumulative impacts, above which it can be considered that further impacts would not be acceptable. It suggests that the addition of further impacts over and above the tipping point could be the turning point where the overall vitality and viability of a community or area would be threatened.

These definitions indicate that cumulative impacts can arise from several aspects of developments. In the case of a single development for example, the combined effect of noise, dust, odours and traffic impacts could be so significant in combination that it would be regarded as unacceptable, even though the impacts may be considered less detrimental when assessed individually. Cumulative impacts could also arise from the additional effects of a single proposal with those of an existing development or developments nearby or one that is planned to take place in the locality in the future. Cumulative impacts could also be generated by the long-term effects of similar developments or even unrelated developments in an area, even where one or more of the original developments has ceased.


For more information about the cumulative impacts and the methodologies for assessment please see the paper, Cumulative Impacts Supporting Paper, January 2015, prepared in support of the Derbyshire and Derby Joint Minerals and Waste Local Plans.




1.3    How can cumulative impacts be assessed and measured?

         The Environmental Impact Assessment regime requires a methodical approach to the assessment of impacts. It requires the identification of a range of potential impacts and an assessment of the scale or significance of those impacts with and without mitigation measures. It establishes a logical approach to the overall assessment of the acceptability of a development proposal. It seeks to identify the point where impacts become so significant that they cannot be regarded as acceptable. This requirement applies to the assessment of cumulative impacts.

         The point at which the cumulative impacts can no longer be regarded as acceptable can be treated as a tipping point. It is important therefore to have a robust and clear method of assessment which can establish that tipping point and enable a thorough assessment of a proposal against a set of policies and criteria. 

         There are a number of different methods available to assess cumulative impacts which vary according to the type of proposal or project under consideration[4]&[5]. Different methods have been devised which involve the application of models, whilst others use matrices and threshold analysis. At present, there is no one standard method which is used to address cumulative impacts of proposals subject to planning applications. Two recent cases, however, have set a precedent for a minimum approach (Mr Justice Burton on Long Moor and the Inspector/Secretary of State in the Telford case[6]). The methodology adopted in these cases consisted of addressing i) successive effects, ii) simultaneous effects from concurrent developments, and iii) combined effects from the same developments.  These would appear to be a comprehensive and an appropriate set of categories for assessing the potential cumulative impacts of mineral and waste planning applications in Derbyshire and Derby.


[1] Guidelines for the Assessment of In direct and Cumulative Impacts as well as Impact Interaction, Hyder, May 1999.

[2] Environmental Assessment in a Changing World, Sadler 1996.

[3] Cumulative Impacts: A Good Practice Guide For The Australian Coal Mining Industry, University of Queensland.

[4] Draft Guidelines on Cumulative Effects Assessment of Plans, EPMG, Imperial College London, 2003.

[5] EIA Newsletter 14, Cumulative Impacts, Manchester University, 2003

[6] High Court case, The Queen (on the application of Leicestershire County Council) v. the Secretary of State for Communities and Local Government and UK Coal Mining Ltd (2007) EWHC Admin 1427.