The use of risk assessment to assist in management of contaminated sites is becoming common practice across the globe. However, significant variability is still observed as a result of its application (e.g. due to differing legislative regimes), both in how risk assessment is implemented and to what extent it is being used to aid sustainable decision-making. This presentation will review the state of play across the globe, including Europe, North America, Latin America and Asia, grouping and mapping countries and regions based upon which ‘tier’ of risk assessment is most commonly used to determine requirements for remediation. The data will then be evaluated to assess whether the use of risk assessment as a decision-making tool is assisting in the sustainability agenda, or in fact resulting in less sustainable approaches being adopted for management of contaminated sites. The hypothesis that the most sustainable management solutions for contaminated sites arise from those countries or regions using higher tier risk assessment practices to determine remediation requirements will be explored.
The concept of ‘tiered’ risk assessment is well recognised globally; four tiers of risk assessment have been defined, although it is acknowledged that the definitions vary between countries:
Tier 1: Problem conceptualisation
The first tier of assessment comprises definition and structuring of the problem, and identification of potential risks, using qualitative methods of assessment.
Tier 2: Filtering Sites
The second tier of assessment focuses on evaluation of contaminated sites using conservative screening levels. When used effectively, this results in confidence as to which sites do not require remediation, and highlighting those for which further consideration is appropriate. Conversely, where misapplied, this can instead result in identification of contaminated sites requiring remediation, and use of conservative screening levels as remediation endpoints.
Tier 3: Site Specific Evaluation of Risks
The third tier of assessment is aimed at reducing uncertainty in the risk evaluation process, typically combining lines of evidence gained through both modelling and measurement. However, the outcome of a Tier 3 risk assessment is, in many cases, still a predicted rather than measured effect.
Tier 4: Significance Testing
The final tier of assessment looks to test whether the predicted effects are occurring, or could reasonably be expected to occur. This concept also known as ‘cause-attribution’ evaluation is most widely applied in evaluation of risks to ecological receptors. It is more occasionally applied for the assessment of risks to human health, for example detailed exposure and response modelling for contaminants in indoor air.
An evaluation will be made as to how the global progression from use of Tier 2 assessments to use of Tier 3 and Tier 4 assessments to determine remediation needs is improving the value of risk assessment in helping with more sustainable decision-making for the management of contaminated sites. The focus of the presentation will be on specific countries identified from the global review as examples in practice. This will include countries where policy shifts are underway (Poland) or under discussion (Germany), and countries where Tier 3 and 4 assessments are already routinely used to guide management of contaminated sites.
Promoting defensible risk-based decisions and sustainability in contaminated land management in Finland
Jussi Reinikainen, Finnish Environment Institute (SYKE), P.O.BOX 140, FIN-00251 Helsinki, Finland, Jussi.Reinikainen@ymparisto.fi, tel. +358 295 251 551
Background
In Finland, risk-based approach is one of the key principles in the management policy on contaminated land. Risk-based decision making is supported by a specific Government Decree and its associated guidance document. Despite the obligatory risk-based approach that has been applied in about 2300 remediation projects between 2007 and 2014, carrying out risk assessments and especially application of their results still involves several complications. Remediation need and its goals, for example, are determined on the basis of the soil guideline values in up to 95 % of the cases, even though they are not legally binding and the site-specific assessment does not support their use. This often results in inconsistent and unjustified decisions, e.g. when remediation is based on ecological guideline values, although ecological risks are not considered as relevant due to land use. In addition, the straightforward use of generic guideline values tends to lead to exhaustive remediation measures, i.e. soil excavation, and ignoring of other risk management options. Thus, the ultimate objectives of the risk assessment framework, such as moving away from fixed concentration thresholds towards real risk-based decisions and more reasonable remedial actions, have remained partly unfulfilled. It was therefore decided that the existing policy instruments need further improvements, and so the above-mentioned guidance document was recently revised.
Revisions on risk assessment guidelines
Reliable risk assessment is a prerequisite for defensible decisions and sustainable risk management. The main objective of risk assessment is to confirm, whether there is an actual need for remediation based on site-specific risks. To achieve this objective in the Finnish context a turnover from over-conservative and sometimes unfounded risk assessments to more realistic and more justified assessments is needed. To contribute to this change and to increase consistency in risk assessments, major revisions in the former guidance on risk assessment were done.
The revised guidelines highlight the importance of representative sampling in order to promote defensible decisions. This requires that the sampling plan is designed solely for the purpose of risk assessment by setting relevant objectives, defining proper decision units (e.g. exposure areas) and ensuring sufficient quality assurance. When sampling can be considered as representative based on these criteria, average contaminant concentration of a decision unit can be used in the risk assessment. Targeted reference values and their application principles for the protection of human health and the quality of the environment, national default values for exposure parameters, detailed instructions for justified use of soil guideline values, restrictions and deficiencies of the risk assessment methodology, and check-lists and recommendations for documentation are also described.
Sustainability in risk management and remediation
In addition to the revisions on risk assessment methodology, a concept of sustainable risk management is introduced in the guidance following the international development. According to the new guidelines, appraisal of sustainability should always be an integral part of remediation planning alongside inferences from a reliable risk assessment. Such appraisal should provide all the necessary information for selecting the most appropriate risk management solutions and to maximize the net-benefits of remediation. This requires balancing between the three components of sustainability, i.e. environmental, economic and social considerations, in a transparent way, including the involvement of relevant stakeholders.
The guidelines provide information for the sustainability assessment and examples of practices that can be generally considered as sustainable. Furthermore, generic recommendations to support decision-making are presented based on such practices. The objectives of these recommendations are to promote sustainable risk management even on sites where site-specific assessment of sustainability is not carried out. The recommendations cover the following themes:
1. possibilities in regional land use planning
2. suitability of risk assessment regarding land use
3. timing of remediation with respect to site redevelopment
4. clean enough top soil on redevelopment sites
5. contaminants of concern
6. applicability of in situ ja on site techniques
7. reuse potential of excavated soils
8. treatment methods for excavated soils and
9. stakeholder participation.
Conclusion
In Finland, the regulatory framework on contaminated sites is rather consistent, but there is a need to increase the appropriate use of risk assessment and to improve the remediation practice. Therefore, the guidelines on risk assessment and management were revised. The objectives of the new guidelines are to promote defensible risk-based decisions and to increase sustainability in site remediation. This is accomplished by specifying the requirements on the mandatory risk assessment procedure and by giving recommendations on good risk management practice.
When evaluating the redevelopment of a 4 km2 industrial area in one of China’s larger cities, several challenges arise :
• A developing soil investigation sector
• Lack of information
• High turn-over of redevelopment of the sites in the industrial area
Available data
With 38 boreholes and 18 groundwater testing well as a data set, the assessment of subsurface conditions on the 4 km2 of land seems impossible. Let alone, estimating the remediation cost of such a large area based on this limited data set.
Lack of data
Take a different look at the available data because the soil investigation business is only starting out in China. Instead of looking for the highest concentrations, look for the most sensitive analytical tools and look at any chemical that is above the detection limit. All data of chemicals that would migrate e.g. by groundwater migration (take into account the retardation factor) can be assessed by back calculation. If they would have easily travelled to the boundary of the site, than the occurrence at the boundary of the site is an indication of what is happening on the site. If any contamination is frequently encountered, even in low concentration, it might by a regional trend. Consider the data set as a Cloud of Data and try to get a view from a distance.
Use additional information (historical aerial pictures) and your experience
If you are not getting all the information, use additional information available and use your experience.
The historical information based on the analysis of historical sets of aerial pictures, allows to determine the evolution of the Foot Print of the industrial activities on various sites. By identifying various features (main production building, tank parks, workshops, etc) some core identification within the foot print is possible.
Compile data in a system of layers
It doesn’t really matter which system you use, but compiling data in a GIS or CAD system will help to comprehend was is happening and to derive some essentials relations between all different sets of information.
Process the data in a multi- criteria data set.
Scoring the information into different sets of criteria, allows to prioritize the information. Part of the criteria are based on the classical source-path-receptor linkages.
The output of the process
One of the main issues here was to find out, ”who” are we working for and how the output of the process would be used. All information was presented in a set of maps of the area.
Contaminated land management is generally based on the assessment of exposure and its comparison to the hazard posed on the ecosystem of identified contaminants. Exposure is calculated from measured environmental concentrations by using transport and fate models and compared to the no effect threshold of a single chemical. In the real environment contamination is typically caused by a mixture of unidentified contaminants and the actual adverse effect is largely influenced by environ¬mental conditions (pH, Eh, humidity), the soil matrix and the living organisms present, meaning that the same concentration of the same contaminant may pose a strong effect or no effect at all.
Direct toxicity assessment (DTA) of contaminated environmental samples ensures high environmental relevance representing all possible interactions between contaminants, ecosystem members and soil phases aggregating the effects of the contaminants present in the sample. In addition to this, DTA can simulate different water and soil uses and real, multiple exposures related to single or more test organisms. DTA gives a risk related result and provides information for direct decision making based on the measured scale of adverse effects. But directly measured toxicity of environmental samples cannot be expressed in concentration thus it does not fit into the chemical risk assessment model and concentration-based screening values applied in environmental management.
The author demonstrates practical examples of applying direct toxicity measuring methods in environmental management:
• The application of bioassay based threshold values instead of concentrations: for treated waste water discharge and remedied soil reuse.
• The use of "no effect" dilution of a contaminated environmental sample for setting environmental quality objectives and planning remedial technologies: toxic metal contaminated soil remediation by a combined chemical and phytostabilization.
• The monitoring of soil remediation by DTA with test organisms of three trophic levels: an example of soil remediation using biochar and organic wastes
To interpret DTA results in a way understandable for a wide range of professionals, the equivalency approach was introduced in an inverse fashion. This way the effect results of DTA can be quantitatively characterized by an equivalent concentration of selected contaminants to bridge the gap between the chemical and biological toxicity models.
References:
Gruiz, K.; Meggyes, T. and Fenyvesi, É. (Eds.) (2014) Engineering Tools for Environmental Risk Management: 1. Environmental Deterioration and Contamination – Problems and their Management. CRC Press. ISBN 9781138001541
Katalin Gruiz, Tamas Meggyes, Eva Fenyvesi (Eds.) (2015)Engineering Tools for Environmental Risk Management: 2. Environmental Toxicology. CRC Press. ISBN 9781138001558
Acknowledgement:
The work was carried out in the frame of the „Terra Preta” project, registration number HU09-0029-A1-2013 supported by the EEA Grants and the Norway Grants within the „Green Industry Innovation Program” of the Norwegian Financial Mechanism 2009-2014.
In many areas of Europe groundwaters use represents the main source for agricultural irrigation due to different reasons: water scarcity, surface waters microbiological pollution, advantages of the use of groundwaters near crops production areas. In Europe around 33% of total water use is for agriculture; this share can reach up to 80% in southern Europe countries.
In the context of the water framework directive the chemical status assessment of surface and groundwater bodies is based on the application of quality standards, but there is not a regulation for use or re-use (effluent of wastewater treatment plants) of waters also for the complexity to derive specific limit values. The quality standards for surface and groundwaters are derived on the basis of the risks for environment and human health (in relation to drinking water and fishery product consumption), but they do not consider the irrigation use.
In Italy the percentage estimated of the use of groundwaters is higher in the islands where represents the 32-48% of total use, while in the continental area the percentage is in the range of 7-18%. The main problems of contamination in Italy are caused by the presence of the organic compounds such as chlorinated solvents (tetrachloroetylene and trichloroetylene) in water wells used for irrigation. These compounds can derive from different sources of pollution (industrial mainly in contaminated sites), are persistent in groundwaters and reliable data on the absorption of this substance by roots and leaves are scarce. The advice is needed in particular when the concentrations are in the range of 2-10 µg/L with levels below or analogous to the drinking water limits. Metals such arsenic, vanadium, lead can be present in high concentrations in groundwaters due to natural and anthropogenic causes; several pesticides have been also detected in groundwater at different concentration levels; other emerging substances for which less data are available can be present in groundwaters bodies in particular near urban areas and in this case the use of biodiagnostic tools such as bioassays in vitro and in vivo should be adviced.
It is evident that the availability of a national guideline establishing the criteria and methods of analysis of the risks associated with the use of water in agriculture is a prerequisite to improve the sustainable management of water resources.
In line with the principles adopted for the water safety plans in relations to drinking waters by WHO a risk assessment framework should be adopted also for the use in agriculture; this framework should include the hazard identification, the hazard characterization and the exposure assessment based on the analysis of the pressure and impacts on the area and on the environmental fate of the pollutants after irrigation and their capacity to bioaccumulate in the different parts of the crops. The risk evaluation should be linked to the management framework related to the quantitative aspects connected to the aquifer recharge capacity.