ABSTRACT

Derelict land can be regarded as land that has been damaged by industrial use or other means of exploitation to the extent that it has to undergo some form of remedial treatment before it can be of beneficial use. Such land usually has been abandoned in an unsightly condition and often is located in urban areas where land for development is scarce. Consequently, not only is derelict land a wasted resource but it also has a blighting effect on the surrounding area and can deter new development. Its rehabilitation therefore is highly desirable, not only by improving the appearance of an area but also by making a significant contribution to its economy by bringing derelict land back into worthwhile use. Accordingly, there is both economic and environmental advantage in the regeneration of derelict land. Land recycling in urban areas also can be advantageous since the infrastructure generally is still in place. Moreover, its regeneration should help reduce the exploitation of greenfield sites and encourage that of brownfield sites. The term ‘brownfield’ normally is applied in a broad sense to land that has been developed previously and as such includes vacant land, with or without buildings, together with derelict and contaminated land. The regeneration of brownfield sites is linked with the process of sustainable development. Hence, the potential for redevelopment of a brownfield site needs to be assessed in terms of economic, environmental and social factors that contribute to the overall concept of sustainable development, as well as site-based factors (Anon., 1999a). The environmental geotechnics of a brownfield site influence its subsequent re-use as well as affecting the costs of bringing the site into a state suitable for redevelopment. The existence of abandoned derelict sites runs counter to the concept of sustainable develop-

ment. Sustainable land use is essential if present-day development needs are to be met without compromising the ability of future generations to meet their needs. A sustainable land use therefore requires derelict sites to be re-used, thereby recovering such sites as a land resource. It has been estimated that two-thirds of the population of the earth will live in cities by 2015, which emphatically highlights the need for more efficient use of urban space, especially in those cities that are growing at a rapid rate. In the European Community there are 52000 ha of derelict land associated with the mining industry alone, 80 per cent of which occurs in Belgium, Britain, France, Germany and Spain (Ferber, 1995). Mabey (1991) reviewed the position of derelict land in Britain, noting that in 1988 there were some 40500 ha of derelict land but that the amount was decreasing. Of the land attributable to industrial dereliction, 94 per cent was considered to justify remediation. Fortunately, attitudes towards derelict land have changed and legislation has been enacted in many countries in the form of planning acts to limit its development and to facilitate its restoration. The use to which derelict land is put should suit the needs of the surrounding area and be

compatible with other forms of land use. Restoring a site to a condition that is well integrated

into its surroundings also upgrades the character of the environment beyond the confines of the site. In the past derelict land in rural areas usually has been reclaimed for agricultural purposes. However, in the European Community in particular, where more efficient food production has meant that areas of farm land are now surplus to requirements, this type of goal has been re-assessed. Furthermore, there is a growing awareness that the quality of life is influenced by cultural heritage, protection of biodiversity and nature conservation. Therefore, derelict land in rural areas can offer opportunities for habitat restoration. In addition, restoration for conservation may prove less demanding financially than restoration to agriculture. Nonetheless, any type of restoration must take account of safety (e.g. in terms of derelict buildings, mine shafts, etc.) and potential problems of pollution off-site. Any project involving the restoration of derelict land requires a feasibility study. This needs

to consider accessibility to the site; land use and market value; land ownership and legal issues; topography and geological conditions; site history and contamination potential; and the local environment and existing infrastructure. The results of the feasibility study allow an initial assessment to be made of possible ways to develop a site and the costs involved. This is followed by a site investigation. Aerial photographs may prove of value, especially for large sites. The investigation provides essential input data for the design of remedial measures and indicates whether or not demolition debris can be used in the rehabilitation scheme. Derelict land may present hazards, for example, disposal of industrial wastes may have

contaminated land, in some cases so badly that earth has to be removed, or the ground may be severely disturbed by the presence of massive old foundations and subsurface structures such as tanks, pits and conduits for services (Fig. 10.1). Contaminated land may emit gases or may represent a fire hazard. Details relating to such hazards should be determined during the site investigation (Pearson, 1992). Site hazards result in constraints on the freedom of action, necessitate following stringent safety requirements, may involve time-consuming and costly working procedures, and affect the type of development. For instance, Leach and Goodyear (1991) noted that constraints may mean that the development plan has to be changed so that the more sensitive land uses are located in areas of reduced hazard. Alternatively, where notable hazards exist, then a change to a less sensitive end use may be advisable. Settlement is another problem that frequently has to be faced when derelict industrial land, which consists of a substantial thickness of rubble fill, is to be built on. If this is not contaminated, then dynamic compaction or vibro-compaction can be used to minimize the amount of settlement. Where the soils are soft, then they can be preloaded, with or without vertical drains, or stabilized by deep mixing whereby cement, lime or cementitious fly ash is mixed into the ground by auger rigs (Thom and Hausmann, 1997). Nonetheless, Leach and Goodyear maintained that there are few derelict sites that cannot be brought back into beneficial use. Derelict sites may require varying amounts of filling, levelling and regrading. As far as

fill is concerned, this should be obtained from on site if possible, otherwise from an area nearby. Reid and Buchanan (1987), for example, mentioned that the derelict Queen’s Dock in Glasgow, Scotland, had been filled with 1.3 million m3 of demolition rubble from old buildings in the vicinity, degradable material such as timber having been removed. Similarly, Hartley (1991) referred to the use of old foundation material that was crushed and used as fill at a site in Middlesbrough, England. Once regrading has been completed, the actual surface needs restoring. This is not so important if the area is to be built over (e.g. if it is to be used for an industrial estate), as it is if it is to be used for amenity or recreational purposes. In the case where buildings are to be erected, however, the ground must be adequately compacted so that they are not subjected to adverse settlement. On the other hand, where the land is to be used

for amenity or recreational purposes, then soil fertility must be restored so that the land can be grassed and trees planted. This involves laying top-soil (where appropriate) or substitute materials, the application of fertilizers and seeding (frequently by hydraulic methods). Adequate subsoil drainage also needs to be installed. Derelict land caused by some earlier industrial operation may contain structures or machinery

of historical interest and worthy of preservation. According to Brown (1998), any assessment of the industrial archaeological value of a site must consider its scientific and engineering interest, its state of preservation and completeness, and its representativeness and rarity. The amenity, recreation and tourism aspects also need to be considered (Fig. 10.2). Brown provided a number of examples of partly or wholly derelict sites in Shropshire and West Yorkshire, England, which had been developed as sites of archaeological interest including the multi-site Ironbridge Gorge Museum in the area where the Industrial Revolution began.