Pär-Erik Back

SCORE: A novel multi-criteria decision analysis approach to assessing the sustainability of contaminated land remediation

The multi-criteria decision analysis (MCDA) method provides for a comprehensive and transparent basis for performing sustainability assessments. Development of a relevant MCDA-method requires consideration of a number of key issues, e.g. (a) definition of assessment boundaries, (b) definition of performance scales, both temporal and spatial, (c) selection of relevant criteria (indicators) that facilitate a comprehensive sustainability assessment while avoiding double-counting of effects, and (d) handling of uncertainties. Adding to the complexity is the typically wide variety of inputs, including quantifications based on existing data, expert judgements, and opinions expressed in interviews. The SCORE (Sustainable Choice Of REmediation) MCDA-method was developed to provide a transparent assessment of the sustainability of possible remediation alternatives for contaminated sites relative to a reference alternative, considering key criteria in the economic, environmental, and social sustainability domains. The criteria were identified based on literature studies, interviews and focus-group meetings. SCORE combines a linear additive model to rank the alternatives with a non-compensatory approach to identify alternatives regarded as non-sustainable. The key strengths of the SCORE method are as follows: a framework that at its core is designed to be flexible and transparent; the possibility to integrate both quantitative and qualitative estimations on criteria; its ability, unlike other sustainability assessment tools used in industry and academia, to allow for the alteration of boundary conditions where necessary; the inclusion of a full uncertainty analysis of the results, using Monte Carlo simulation; and a structure that allows preferences and opinions of involved stakeholders to be openly integrated into the analysis. A major insight from practical application of SCORE is that its most important contribution may be that it initiates a process where criteria otherwise likely ignored are addressed and openly discussed between stakeholders.

Cost-benefit analysis as a part of sustainability assessment of remediation alternatives for contaminated land.

There is an increasing demand amongst decision-makers and stakeholders for identifying sustainable remediation alternatives at contaminated sites, taking into account that remediation typically results in both positive and negative consequences. Multi-criteria analysis (MCA) is increasingly used for sustainability appraisal, and the Excel-based MCA tool Sustainable Choice Of REmediation (SCORE) has been developed to provide a relevant and transparent assessment of the sustainability of remediation alternatives relative to a reference alternative, considering key criteria in the economic, environmental and social sustainability domains, and taking uncertainty into explicit account through simulation. The focus of this paper is the use of cost-benefit analysis (CBA) as a part of SCORE for assessing the economic sustainability of remediation alternatives. An economic model is used for deriving a cost-benefit rule, which in turn motivates cost and benefit items in a CBA of remediation alternatives. The empirical part of the paper is a CBA application on remediation alternatives for the Hexion site, a former chemical industry area close to the city of Göteborg in SW Sweden. The impact of uncertainties in and correlations across benefit and cost items on CBA results is illustrated. For the Hexion site, the traditional excavation-and-disposal remediation alternative had the lowest expected net present value, which illustrates the importance of also considering other alternatives before deciding upon how a remediation should be carried out.

Value of Information Analysis in Remedial Investigations

Abstract Site investigations of contaminated land are associated with high costs. From a societal perspective, just enough economic resources should be spent on investigations so that societys limited resources can be used optimally. The solution is to design investigation programs that are cost effective, which can be performed using value of information analysis (VOIA). The principle of VOIA is to compare the benefit at the present state of knowledge with the benefit that is expected after an investigation has been performed. A framework for VOIA of site investigations is presented based on Bayesian risk-cost-benefit decision analysis. The result is an estimate of the value of an investigation program and, for specific problems, the optimal number of samples. The main strength of the methodology is that it promotes clear thinking and compels the decision maker to reflect on issues that otherwise would be ignored. The main weakness is the complexity of VOIA models.

What's the point? The contribution of a sustainability view in contaminated site remediation

Decision support tools (DST) are often used in remediation projects to aid in the complex decision on how best to remediate a contaminated site. In recent years, the sustainable remediation concept has brought increased attention to the often-overlooked contradictory effects of site remediation, with a number of sustainability assessment tools now available. The aim of the present study is twofold: (1) to demonstrate how and when different assessment views affect the decision support outcome on remediation alternatives in a DST, and (2) to demonstrate the contribution of a full sustainability assessment. The SCORE tool was used in the analysis; it is based on a holistic multi-criteria decision analysis (MCDA) approach, assessing sustainability in three dimensions: environmental, social, and economic. Four assessment scenarios, compared to a full sustainability assessment, were considered to reflect different possible assessment views; considering public and private problem owner perspectives, as well as green and traditional assessment scopes. Four real case study sites in Sweden were analyzed. The results show that the decision support outcome from a full sustainability assessment most often differs to that of other assessment views, and results in remediation alternatives which balance trade-offs in most of the scenarios. In relation to the public perspective and traditional scope, which is seen to lead to the most extensive and expensive remediation alternatives, the trade-off is related to less contaminant removal in favour of reduced negative secondary effects such as emissions and waste disposal. Compared to the private perspective, associated with the lowest cost alternatives, the trade-off is higher costs, but more positive environmental and social effects. Generally, both the green and traditional assessment scopes miss out on relevant social and local environmental secondary effects which may ultimately be very important for the actual decision in a remediation project.