Dealing with Contaminated Land

Land is a finite and valuable resource. Identifying and dealing with contaminated land is important in order to support increased quality of life for communities and conservation of biodiversity. 

Contamination of land can harm humans and the environment and needs to be controlled. Uncertainty about the existence and potentially hazardous nature of land contamination reduces confidence in existing and planned development on brown field sites and so increases demand for green field sites.1 

During recent decades, considerable areas of contaminated land have been identified and many of these have been dealt with, so that they can be used safely for new development or returned to a semi-natural condition. However, much contaminated land is either not yet identified or is described inadequately. Furthermore, knowledge is incomplete about the impacts of land contamination on humans and natural systems. 

The acceptability of the risks presented by contaminated land sites is not a 

1 Urban Task Force, Towards an Urban Renaissance, SPON, London, 1999. 

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Kersten, M. Forstner, U. (1995) In Chemical Speciation in the Environment, Ure, A.M. and Davidson, C.M. (eds), Blackie Academic Professional, Glasgow, 234—275. ISBN 0-87371—697—3. Kibblewhite, M. (2001) Identifying and dealing with contaminated land, In Assessment and Reclamation of Contaminated Land, Hester and Harrison (eds), 16, Royal Society of Chemistry (RSC). ISBN 0-85404—275-X. 

Created the Environment Agency (EAJ and the SEA for Scotland. Contains detailed provisions for dealing with a range of environmental issues including air quality contaminated land reinforcing the polluter pays principle water quality, with the EA empowered to require action to prevent water pollution and to require polluters to clean up after any pollution episode. 

As piirt of each haz, irdous waste remedial action, the contamination at the site must be assessed. The options for remedial action to remo c or otherwise deal with hazardous materials will depend on the nature of the coutamiiuition lliat will be allowed to remain on site tifter cletmup. Thus there must be plans for site remediation to cover any accidental or emergency discharges to land or soils that might develop. 

One way that contaminants are retained in the subsurface is in the form of a dissolved fraction in the subsurface aqueous solution. As described in Chapter 1, the subsurface aqueous phase includes retained water, near the solid surface, and free water. If the retained water has an apparently static character, the subsurface free water is in a continuous feedback system with any incoming source of water. The amount and composition of incoming water are controlled by natural or human-induced factors. Contaminants may reach the subsurface liquid phase directly from a polluted gaseous phase, from point and nonpoint contamination sources on the land surface, from already polluted groundwater, or from the release of toxic compounds adsorbed on suspended particles. Moreover, disposal of an aqueous liquid that contains an amount of contaminant greater than its solubility in water may lead to the formation of a type of emulsion containing very small droplets. Under such conditions, one must deal with apparent solubility, which is greater than handbook contaminant solubility values. 

Transport of contaminants by surface runoff is illustrated in the experimental results of Turner et al. (2004), which deal with the colloid-mediated transfer of phosphorus (P) from a calcareous agricultural land to watercourses. Colloidal molybdate-reactive phosphorus (MRP) was identified by ultrafiltration associated with particles between l am and Inm in diameter. Colloidal P compounds can constitute a substantial component of the filterable MRP in soil solution and include primary and secondary P minerals, P occluded or adsorbed on or within mineral or organic particles, and biocolloids (Kretzschmar et al. 1999). 

The substantial changes include more emphasis on organic chemistry, soils, contaminants in continental water and remediation of contaminated land. T> do this effectively, the terrestrial environments chapter from the first edition has been split into two chapters dealing broadly with solids and water. We have reorganized the box structure of the book and have placed some of the original box material, augmented by new sections, to form a new chapter outlining some of the basic chemical principles that underpin most sections of the book. 

Despite these qualifications, vitrification has some advantages. The vitreous mass is chemically inert and has durable physical properties that lock up contaminants effectively. This is a key advantage when dealing with radioactive contaminants (White et al., 1996). Under some circumstances, the glassy mass can be reused, and some of the energy costs may be recuperated. If the vitrified mass is to be land-filled, the reduction in waste volume is an added cost-saving benefit, in addition to the very inert condition of the glassy material. 

This book attempts to cover chemical and ecotoxicological analysis related to routine contaminated land investigations. It does not cover analysis related to research or specialist one-off project type investigations. The following chapter deals with soil analysis method requirements, how methods should be validated and the need for all methods to meet clearly defined performance requirements. It also covers quality assurance/quality control aspects. Chapter 3 covers the key, and problematic area of sample homogenisation and the initial sample preparation. Chapter 4 covers the analysis of metals and elemental... 

Other Approaches to Definition. There have been other working definitions in policy and practice, but specific legal definitions are of course only developed at the point at which a definition is needed to drive some particular statutory process. The definition will then be focussed on the particular needs of that process. The Part IIA contaminated land definition is quite deliberately restricted to the categories of site that Part IIA is intended to deal with—that is, sites that are currently presenting unacceptable risks to human health and the wider environment. The definition describes land where the contamination is not just present, but where it is, or could be, causing a particular problem. 

The existing statutory regimes dealing with land contamination problems had a variety of different liability tests, each of which presented there own difficulties in practice when applied to land contamination, and were not integrated in their approaches ... 

Tests 4, 5 and 6— changes to substances , escaped substances and introduction of pathways or receptors —deal with different types of circumstances where one appropriate person has, in effect, left the site in a safe condition (notwithstanding the fact that he has caused or knowingly permitted a contaminant to be present) only for another person subsequently to change the condition of the land such that there is now a significant pollutant linkage. The tests were included in effect to transfer liability to the person who made the difference. 

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