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GROUP 3 Contaminated Land
Working group members and contributors
David Cooke | Jacobs Babtie |
Robert Cuthbertson | Scottish Government |
Sarah Hammill | West-Dunbartonshire Council |
Andrew Hursthouse | University of the West of Scotland (Chair) |
Ann Jobson | Envirocentre |
Graeme Paton | University of Aberdeen/Remedios |
Martin Valenti | Scottish Environment Protection Agency |
Contaminated Land
Strategic Objective:
To incorporate soil function in the remediation and management of contaminated land.
Outline of the issue
4.1 Soil is acknowledged to be a repository for a wide range of environmental pollutants. Contaminated land ( CL) is a consequence of these substances (which may be hazardous) associating with the soils and impacting on the function and hence utilisation of soils. The most important Chemicals of Concerns (CoCs) are those that impact on the wider environment when pollutant linkages are formed between contamination sources and identified receptors (living or inanimate). Pollutant linkage should be recognised by considering it as one of a key set of environmental media into which soil can be sequestered. In Scotland this is a consequence of a century of industrialisation. Such activities introduced a cocktail of contaminants through discharges to the atmosphere, direct disposal or loss of material to land, and direct discharge or leaching of contaminants into surface water and groundwater. The introduction of increasingly holistic environmental regulatory systems (which considers all media) has reduced the direct impact from ongoing point source emissions and regulated the handling and disposal of contaminated materials. This means that future contamination of land is most likely through diffuse pollution rather than the historic impact of point sources. As a strategy, the impact of historic contamination as well as predominantly diffuse contamination of the atmosphere (vehicle and energy production) or via land spreading of materials (pesticides, fertilisers, organic amendments) must be considered. Whilst detailed data sets do not exist, it is likely that the dominant CoCs are heavy metals, mineral oils waste combustion energy production (see EEA, 2007).
4.2 The introduction of "emerging pollutants" through for example increases in industrial waste water and solid waste treatment and land cultivation / urbanisation should also be assessed and considered as future threats.
4.3 This contribution focuses on the issues of immediate and future soil management in relation to the formal identification of contaminated land. This is determined by the assessment of the significance of risks to human health and or to designated environmental receptors (i.e. as defined in Part IIa of EPA, 1990). The urge to assess harm is most likely to be conducted through investigations under PAN33. Assessment is based on a sequence of evaluation and identification steps which require in situ investigation and the quantification of risks to identified receptors, and the defined term being related to the cause or potential to cause significant harm.
4.4 Whilst it is recognised that much contaminated land in Scotland is linked to past urban and industrial development, there are numerous locations where specific historical activities have resulted in significant potential for contamination. The formal designation of CL reflecting the application of an assessment process and the test of risk to a sensitive receptor. The presence of vacant and derelict land (as reported in the annual Scottish Vacant & Derelict Land Survey) does not necessarily correlate with contaminated land. Consequently it is recognised that interaction between CL and the Scottish Soil Strategy is as much linked to human behaviour (influencing risk assessment - exposure, intended use etc) as it is to the natural soil environment. Information on the nature and extent of (identified) contaminated land is absent.
Impact on Soils
4.5 Risk (the likelihood and impact of harm occurring) to soil function from the presence of significant levels of contamination are difficult to both determine and to predict the risks. The terrestrial ecosystem, of which soil is an integral component, needs to be studied and interpreted at many levels to allow systematic evaluation in the presence of multiple "other factors" (e.g. Doichinova et al., 2006; Lehmann & Stahr, 2007). The potential for substances to cause "harm" to particular soil components are widely reported in the toxicology/ ecotoxicology literature, but the functioning of the ecosystem within a multi substance and spatially and temporally variable framework introduces a considerable degree of uncertainty when developing an appropriate and workable strategy. Such uncertainty is difficult to quantify.
4.6 How does CL arise and what does it do to the soil function? CL is recognised to be widely varying in character and severity, even within a site. Dose alone does not explain the potential for harm as the inherent binding of the soil will derive the bioavailable concentration and form. A linkage of key soil parameters to pollutant modes of action and receptor sensitivity is required to empirically tests and then model these issues. Soils can be conditioned through long term exposure to diffuse CoCs and may be as functionally diverse and as active as those from pristine habitats. The term function as a biogeochemical aspect and as a scale issue must be defined to assess the impact and extent of the CoC. Furthermore CoC interaction may cause antagonistic, synergistic or simple additive responses to the measured function/ defined receptor. Implications of soil contamination for human health are still uncertain (Hough, 2007). Table 4.1 provides brief commentary on soil functions in relation to "typical" CL management.
4.7 A range of remediation techniques may be identified by the risk based evaluation process, but these do not necessarily take into account the preservation or creation of soil function. The selection of a final option (which may include more than one remedial technique) is dependent on not only the available technology but also social and economic conditions with proposed end use in mind ("fit for use" rather than fit regardless of use); which in turn is a consequence of a risk-defined end-point. The range of individual activities may be viewed to enhance or degrade soil function during their application and overall the development of the site or its remediation may be positive or negative in terms of soil function.
Table 4.1 Outline of soil functions in relation to 'typical' CL management
Soil function | Contaminated land impact |
|---|
Providing the basis for sustainable food and biomass production from our agricultural and forestry industries; | CL likely to degrade soil capacity through its presence. The remediation of contamination is likely to permit the production of biomass (but not food production, unless a specific objective) as a potential additional benefit. |
Regulating our water supply and protecting it from contamination; | As a general principle, water supply regulation is likely to be degraded by a number of common remediation approaches that involve cutting source-pathway-receptor linkages for human health. On the other hand protection of the water environment from contamination may be a primary objective of some remediation schemes and SEPA regulation to reduce impact of contaminants to below drinking water standards is a positive impact on water quality. |
Providing nationally and internationally valued habitats; | Land contamination may be a threat to some designated habitats or other sites, depending on the pollutant linkages that are actually present. Sites that are remediated are unlikely to generate soils of a quality fit to underpin designated status and the act of remediation may in itself cause disruption and even destruction of established soils and related ecosystems (Smith et al 2006). |
Storing carbon and maintaining the balance of gases in the air | The presence of contamination is likely to reduce biologically mediated carbon storage capacity and other atmospheric interactions involving site soils. Remediation is likely to allow a functioning soil to be established, albeit that this may be in isolation from underlying retained contaminated materials. |
Sustaining biodiversity; | Biodiversity should be considered at a molecular, species, community and functional level. The lack of disturbance and built development on contaminated sites may be beneficial in terms of biodiversity, dependent on the direct impacts of the contamination itself. Remediation is commonly linked to commercial or residential site development which would be likely to have a negative impact on biodiversity. Some contaminated sites are remediated to a public open space or even conservation end-use with consequent more beneficial impacts on biodiversity. |
Preserving of our cultural and archaeological heritage; | Industrial heritage associated with an important socio economic development period in our history is often the cause of CL remediation need. Remediation can have major negative impacts in terms of the physical disturbance or even wholesale removal of the archaeological remains. |
Providing raw material; | Potential for recovery and re use of wastes on a CL site through to selection of remediation/end use where biomass production may be favoured. |
Providing a foundation for buildings and roads | Contamination can lead to potentially negative impacts on foundations due to chemical attack, dependent on the nature of the contamination and the development planned. Some remediation techniques such as cement stabilisation and encapsulation can provide positive benefit in this context. Most remediation schemes linked to development of a site will include aspects to ensure the geotechnical suitability of the site. |
Impact in Scotland
4.8 Climate change: direct impacts from changes in climate parameters and nature of climatic cycles; indirect impacts from changes in behaviour - flooding and shift in agricultural/soil use, erosion. Climate change scenario envisages changes in temperature and moisture regimes as well as disturbances in the periodicity. Wetter and cooler temperatures and higher degree of saturation is suggested ( SEPA, 2006). This enhances the significance of a major pollutant pathway and also the chemical processes influencing contaminants - their weathering and transport. It also influences the technical requirements for containment or dispersal, but overall unlikely to be outside the current design limitations, as far as Scotland is concerned. There are similar potential implications for the aftercare of remediated sites where contamination has been isolated but which remains on site.
4.9 The Scottish approach to contaminated land is very closely linked to UK wide initiatives, albeit under a slightly different legislative framework. The Scottish Government has committed targeted spending towards the direct remediation of contamination, but this has not included any specific objectives relating to soil quality (statistics available from the Scottish Government website: SG, 2007).
4.10 Research: CL research traditionally has been focussed on new techniques for investigation and remediation of the contamination under a variety of land use scenarios. CL research is very wide ranging in terms of the sponsoring organisations and interaction with large scale multi-discipline research programmes, but soil function and ecological end-points have not previously featured in such programmes apart from those looking directly at biological remediation techniques. Many examples of CL related research activities/initiatives/ and fora (table 4.2).
Table 4.2 Research Fora involved in Contaminated Land related research activities
EU/world wide | UK | other |
|---|
NICOLE, CARACAS etc SNOWMAN EURODEMO NATOCMS EUGRIS web portal | CL:AIRE SNIFFER SETN/ IPM Net | University activity e.g. SAGES; CLARRC, individual groups in UK and world wide. Policy: NSCA/ SCLF etc |
4.11 Data and monitoring: Soil functionality is not currently a target of contaminated land assessments and data are not gathered routinely. Existing data and monitoring of contaminated land focuses on the identification and remediation of contaminated land and the authorisation of development (planning). All such data tends to be very site specific in nature and does not address more regional (diffuse) contamination issues. Whilst this information is likely to available, in addition to voluntary remediation activities, it is unlikely to be in a suitable form for wider dissemination. Contamination from deliberate application of materials (land spreading of both waste and fertiliser) to land is also excluded from routine contaminated land datasets.
A review of where main areas of regulation/policy addressing contaminated land.
Policy Area | Soil and Contaminated Land provisions | Outlook/impacts for SSS |
|---|
Planning and Development Control | SEA/ EIA for development plans and major site specific proposals includes adverse impacts on soils (in terms of physical loss or cause of new contamination). | Provides a framework for strategic protection of soil resource and the consideration of soil function as an integral part of EIA. |
Planning permission for development of CL to ensure fit for use, but soil function rarely a specified condition. | Provides a mechanism for achieving site specific soil function protection or enhancement as a fundamental part of development (similar to SUDs). |
EPA part IIa | Obligation to assess, report and remediate CL, (no specific soil function remit). Initial prioritisation mostly completed and good progress with site identification and investigation. Key PIs to facilitate review and monitoring of progress now in place. Initial data being analysed. | Would require significant expansion of the Part IIa remit to include general soil function as a LA responsibility. Consideration of soil function as a fundamental part of statutory action on contaminated land sites is possible, but level of activity / scale of impact likely to be very low. |
PAN33 | Land as a component for planning. | |
Water Framework Directive | Control of impacts on water environment to ensure good status Indirectly requires soil contamination to be managed - both point and diffuse components. | Ongoing implementation of the WFD likely to raise awareness of soil quality as an influencing factor on water quality. WFD potentially of use as a justification of increased pressure for improving soil quality. |
IPPC/ PPC | Licensing dependent on protection of soil and groundwater and management of waste. Return site to original condition | Potential revision to include more monitoring and remediation requirements for site operators specifically aimed protection of soil function. |
Other ind. process regs incl. COMAH, H&S | Maintain and monitor process and health and safety indirectly preventing accidental release of materials to soil. | Useful in terms of ongoing reduction in the potential for contamination of soil through safe operation of site. |
Waste | Landfill current and past, land spreading of waste | Future potential to contaminate, on going monitoring obligation through site closure |
Environmental Liability | Damage to land through pollution - "polluter pays" | Should help to ensure future contamination is prevented and/or polluter identified? |
Soil Framework Directive | A major potential impact on CL and soil strategy in Scotland. Undergoing extensive debate and revision of current format is likely. | Current draft of SFD provides a potentially increased burden on regulators to manage CL. Aim is to prevent future contamination and preserve soil functions. A risk based approach is favoured for CL but responsibility for data on all potentially contaminated land (defined range of activities and dangerous substances). Soil function preserved and may contradict protection of human health and sensitive receptors. |
4.12 Baseline/background soil conditions relate more to impact of diffuse processes on soil contamination, rather than individual site contamination issues (spill / leak / deposited solid material type), examples of background assessments include:
- SEPA, 2001 & 2006 (state of the environment reports).
- EA, 2007 (pollutants in soil and herbage survey).
- FOREGS, 2006 (geochemical baseline survey).
- Towers et al.,2006 (summary of threats to soil in Scotland).
- Specific urban data sets e.g. BGSGBASE ( BGS, 2007); URBSOIL (Madrid, 2006), (mixed data for urban regional assessment).
4.13 Awareness and policy integration: are CL issues sufficiently well recognised by all stakeholder groups? Is it widely recognised that CL management has wider environmental impacts? The current process is working (land is developed and remediated) but does not address the soil function aspects with enough rigour.
Outlook: Policy coverage: current and emerging
4.14 Many aspects within current policy cover the release and movement of contamination through the soil medium. There is still a tension between soil function and this aspect. The SFD has the potential to impose this obligation but also to increase the complexity of action on the ground. Are there opportunities to incorporate the high level aims of the SFD into current procedures?
References
BGS (2007) Geochemical Baseline Survey of the Environment (G- BASE) Research activities
http://www.bgs.ac.uk/gbase/research.html
Doichinova, V., Zhiyanski, M., Hursthouse, A. (2006) Impact of urbanisation on soil characteristics, Environmental Chemistry Letters 3 (4), 160-163
EA (2007) UK Soil & Herbage Pollutant Survey No 1 Introduction & summary, Environment Agency June 2007 ISBN: 978-1-84432-692-1.
EEA, (2007) Progress in management of contaminated sites ( CSI 015) - Assessment published Aug 2007
http://themes.eea.europa.eu/IMS/ISpecs/ISpecification20041007131746/IAssessment1152619898983/view_content
FOREGS (2006) baseline metals in crust
http://www.gtk.fi/publ/foregsatlas/
Hough, R.L., (2007) Soil and Human health: an epidemiological review, Eur J Soil Science, 58, 1200-1212.
Lehmann, A. & Stahr, K (2007) Nature and significance of anthropogenic Urban Soils, J Soils & Sediments, 7(4) p 247-260.
Madrid, L., Diaz-Barrientos, E., Ruiz-Cortés, E., Reinoso, R. Biasioli, M., Davidson, C.M., Duarte, A.C., Grcman, H., Hossack, I., Hursthouse, A., Kralj, T., Ljung, K., Otabbong, E. Rodrigues, S. Urquhart, G.J., Ajmone-Marsan, F. (2006) Potentially Toxic Metals In Urban Soils Of Six European Cities: A Pilot Study On Selected Parks, Journal of Environmental Monitoring. 8, 1158-1165.
SEPA (2001) State of the Environment: Soil Quality Report, Scottish Environment Protection Agency, ISBN: 1-901322-17-2
SEPA (2006) State of Scotland's Environment 2006, Scottish Environment Protection Agency, ISBN: 1-901322-65-3
SG (2007) http://www.scotland.gov.uk/Topics/Environment/Pollution/17314/8939 (contaminated land web pages Scottish Government)
Smith, R., Pollard, SJT, Weeks, JM & Nathanail, CP (2006) Assessing significant harm to terrestrial ecosystems from contaminated land, Soil Use Man 21, 527-540.
SVDL (2007) Scottish Vacant & Derelict Land survey:
http://www.scottishexecutive.gov.uk/Publications/2007/01/30094119/1
Towers, W. Grieve, I.C. Hudson, G. Campbell, C.D. Lilly, A. Davidson, D.A. Bacon, J.R. Langan S.J. and Hopkins D.A. (2006) Scotland's Soil Resource - Current State And Threats, Environmental Research Report 2006/01, Scottish Executive, Edinburgh. ISBN 0 7559 6260 5
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