Visual Impact Assessment in British Oil and Gas Developments1 Dennis F. Gillespie2/ Brian D. Clark3/ Abstract: Development of oil and gas resource in the North Sea has led to the application of visual impact assessment techniques to onshore oil and gas developments in the United Kingdom. Formal visual impact assessment methods are needed to supplement landscape evaluations and site selection studies. Three major orientations of British visual impact assessments are: the delineation and mapping of the zone of visual influence, or viewshed; the preparation of accurate graphic representations of the proposed facility; and, the collaboration of engineering and design professionals in all phases of facility plan- ning and design. Visual impact assessments have been successfully applied in case studies throughout the United Kingdom. Formal methods and techniques for visual impact assessment will continue to evolve and their application will extend beyond oil and gas developments to include major energy and other industrial facilities. INTRODUCTION every, "Minister, government department and public body to have regard to the desirability Visual resource management has a long of conserving the natural beauty and amenity established tradition in the United Kingdom. of the countryside in all their functions Since the Town and Country Planning Act of related to land" (Cullingworth 1976). Con- 1947 and the National Parks and Access to the sequently, the preservation of amenity is a Countryside Act of 1949, landscape management basic objective of all planning policy. for amenity has been a statutory requirement However, nowhere in the acts or their accompany- (Hall 1975). ing legislation is the term "environmental impact assessment" used, nor is there a More recently, the Countryside (Scotland) statutory requirement for impact assessment Act 1967 and the Countryside Act 1968 require as there is in the U.S.A., under the National Environmental Policy Act. Rather, local and 1/Submitted to the National Conference on regional planning authorities have considerable Applied Techniques for Analysis and Manage- power to require, on a case by case basis, ment of the Visual Resource, Incline evidence that a proposed development will not Village, Nevada, April 23-25, 1979. injuriously affect the environment. With few exceptions, all development requires the 2/ Visiting Research Fellow, University of prior approval of the local planning authority, Aberdeen, Scotland, and Frank Knox Memorial and the authority has almost unlimited dis- Fellow 1978-79, Graduate School of Design, cretion as to what documentation will be Harvard University, Cambridge, required before planning approval will be Massachusetts. granted. This is known as the "Development 3/Project Director, Project Appraisal for Control Process" and many planning professionals Development Control (PADC) Research Unit, argue that it is sufficient, and a separate, Department of Geography, University of formal environmental impact assessment process Aberdeen, Scotland. is not necessary. Others, including Thorburn 645 (1978) argue that the development control process based on their professional opinion.5/ Often can only be improved by incorporation of some planning officers and consultants developed form of environmental impact assessment. formal methods of landscape evaluation and applied them in comprehensive county and In the last few years increasing concern regional studies. Among the best known work has been expressed about the effects of new is that of Fines (1968), and of Land Use large scale development on the quality of the Consultants (1971), but numerous methods have environment and the ability of the planning been developed, applied and reviewed.6/ While and development control process to take these certain methods were criticized,7/ most were effects into account. Since 1970, the offshore generally accepted as legitimate and lands discovery and development of oil and gas were subsequently designated for conservation. resources in the North Sea has placed tremendous pressures onshore, particularly in Scotland, Site Selection for development sites for associated industrial facilities. This situation prompted the Landscape evaluations are successful in central government to examine the possibility rural environments where development pressure of incorporating into the planning system is low, several alternate development areas formal methods and techniques of environmental are available and the type of development is impact assessment, including visual impact small scale land uses, already present in the 4/ assessment. area. With the increase in pressure for large scale industrial developments in the Since October 1973 the Project Appraisal rural countryside and along the coastline, for Development Control (PADC) Research Unit the traditional landscape evaluation begins at the University of Aberdeen has been studying to lose its effectiveness as a method of the methods and techniques of impact assessment restricting development. Industrial site used in the United Kingdom and abroad, with selection choices often extend well beyond particular emphasis to their application in county or regional boundaries. For certain appraisal of oil and gas related development. facilities there may be literally only a Drawing upon the PADC work, this paper presents handful of sites within a large region that a survey of techniques for visual impact can accommodate the installation for engineering assessment applied to onshore oil and gas or safety considerations. Site selection may developments in the United Kingdom. It also be influenced by government policy re- discusses both general approaches used in stricting certain developments from vast areas visual impact assessment and techniques used and encouraging there location in others. The in specific projects. Scottish Development Department (1971) identi- fied certain segments of the Scottish coastline where oil and gas related industries are to be NEED FOR VISUAL IMPACT ASSESSMENT discouraged. The identification of the coastal segments to be conserved was based mainly on Landscape Evaluation their "scenic quality" as judged through a series of landscape evaluations. Prior to the discovery of North Sea oil and gas the approach planning authorities In other cases, a political decision may used to protect and manage the visual resources be made to locate within a certain region for of the countryside was the preparation of a employment and other social and economic county or regional landscape evaluation. The considerations, or, the argument may be made evaluation was intended to classify the study that a particular facility site is the only area into homogeneous tracts or zones suitable location and is necessary in the according to its relative visual quality. The national interest, regardless of the immediate particular high quality tracts identified impacts on local amenity. Such an argument would then be designated for conservation was advanced when planning approval was purposes on the local development plan and requested to develop a concrete offshore any incompatible development proposals would production platform fabrication yard at be excluded. Drumbuie, near the mouth of Loch Carron on Sometimes recognized experts were commis- sioned and asked for a landscape evaluation 5/ See for example Murray (1962). 6/ See for example Robinson, et al. (1976), Dunn (1974), and Clark et al. (1976h). 4/ Two major central government funded research reports resulted, see Catlow and Thirlwall 7/ See for example Brancher (1969). (19771, and Clark et al. (1976a). 646 the west coast of Scotland (Baldwin and The PADC Research Unit at the University Baldwin 1975). The application was finally of Aberdeen has suggested a simple technique denied, but only after the Secretary of State for determining the zone of visual influence for Scotland conducted one of the most extensive directly from topographic maps (Clark et. al. public inquiries on a development issue to that date. 1976b). First developed by Hebblethwaite (1973) for use by the Central Electricity In situations such as these, the role of Generating Board, the technique considers two the landscape evaluation is to guide forward factors, topography and horizontal distance planning by identifying suitable sites based from the installation. It does not easily on amenity concerns. To be effective, they allow for consideration of existing vegetation must inevitably precede site selection. Once or structures although the technique can be a site has been chosen, comprehensive visual adapted to include them. impact assessments during detailed project appraisal become a significant factor in Two inexpensive pieces of equipment are deciding whether development should proceed. required, a transparent ruled "height plate," corresponding to elevation, and a transparent "sight line," (Clark 1976b). The technique VISUAL IMPACT ASESSMENT involves laying the sight line over a large scale topographic map projecting away from Visual impact assessment to date in the facility in any desired viewing direction. Britain has exhibited three major orientations. The height plate is superimposed over the sight The first is the delineation of the "Zone of line corresponding to the maximum height of Visual Influence," or what is commonly referred the facility. Proceeding outward from the to in the United States as the "viewshed." facility, visible and invisible points along That is, a zone of adjacent land from which the sight line can