Prioritizing groundwater remediation policies: a fuzzy compatibility analysis decision aid

The implementation of groundwater remediation strategies in contaminated areas includes not only a cost-benefit analysis and an environmental risk assessment but also another type of study called compatibility analysis. A compatibility analysis targets the interactions between remediation technologies and site characteristics, such as the types of active contaminants and their concentrations, soil composition and geological features, etc. The purpose of this analysis is to identify the most compatible remediation plan for the contaminated site. In this paper, we introduce a decision support system for the prioritization of remediation plans based on their estimated compatibility index. As this model receives data in terms of linguistic judgments and experts' opinions, we use fuzzy sets theory to deal with these uncertainties. First, we break down the concept of compatibility into the measurable factors. Then by using a multiple-attribute decision-making (MADM) outline, we compute a factorial, regional and overall compatibility indicator for each plan. Finally, by comparing these generated indicators, we rank the remediation policies.     

An overview and analysis of site remediation technologies

This paper presents an analysis of the site restoration techniques that may be employed in a variety of contaminated site cleanup programs. It is recognized that no single specific technology may be considered as a panacea for all contaminated site problems. An easy-to-use summary of the analysis of the important parameters that will help in the selection and implementation of one or more appropriate technologies in a defined set of site and contaminant characteristics is also included.     

Field-scale remediation of a metolachlor-contaminated spill site using zerovalent iron

Pesticide spills are common occurrences at agricultural cooperatives and farmsteads. When inadvertent spills occur, chemicals normally beneficial can become point sources of ground and surface water contamination. We report results from a field trial where approximately 765 m3 of soil from a metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] spill site was treated with zerovalent iron (Fe0). Preliminary laboratory experiments confirmed metolachlor dechlorination by Fe0 in aqueous solution and that this process could be accelerated by adding appropriate proportions of Al2(SO4)3 or acetic acid (CH3COOH). The field project was initiated by moving the stockpiled, contaminated soil into windrows using common earth-moving equipment. The soil was then mixed with water (0.35-0.40 kg H2O kg(-1)) and various combinations of 5% Fe0 (w/w),2% Al2(SO4)3 (w/w), and 0.5% acetic acid (v/w). Windrows were covered with clear plastic and incubated without additional mixing for 90 d. Approximately every 14 d, the plastic sheeting was removed for soil sampling and the surface of the windrows rewetted. Metolachlor concentrations were significantly reduced and varied among treatments. The addition of Fe0 alone decreased metolachlor concentration from 1789 to 504 mg kg(-1) within 90 d, whereas adding Fe0 with Al2(SO4)3 and CH3COOH decreased the concentration from 1402 to 13 mg kg(-1). These results provide evidence that zerovalent iron can be used for on-site, field-scale treatment of pesticide-contaminated soil.     

The development and application of a multilevel decision analysis model for the remediation of contaminated groundwater under uncertainty

A study was initiated which combined elements of stochastic hydrology, risk assessment, simulation modeling, cost analysis and decision making to define the optimum remediation choice(s) for a Superfund site in the southern United States. The effort focused upon the premise that groundwater remediation is inherently complex due to uncertainties in the geological matrix as well as in contaminant concentrations at points of compliance and/or exposure. The technical analyst should supply the decision maker with estimates of these uncertainties as well as the cost penalties required to reduce them to manageable levels. Monte Carlo transport modeling was employed to define the probability of contaminant excursions from the site, while geostatistical simulation identified a joint plume configuration and its attendant probability. Bayesian modeling was used to define the worth of additional data. These individual components were combined within a Decision Model to identify optimum remediation configurations for a given levels of risk tolerance which could be supplied by the decision maker or affected community. Sensitivity analyses were conducted to define ranges over which the decision would not be affected by variation in the respective decision parameter.     

A technicoeconomic approach for the selection of a site remediation strategy--part A: theory

A technicoeconomic model is developed to select an optimal strategy for the remediation of a contaminated site and to determine the value of this remediation strategy. The model is an extension of actual cost-benefit analysis, with consideration of "irreversible" remediation technology choices, technology effectiveness, and uncertainty on the site's level of contamination. The model considers the possibility of reducing uncertainty by both acquiring more and better information on the level of contamination and by offering the decision-maker the opportunity to reevaluate his decision and switch to a more appropriate technology. It is believed that this model will help decision-makers in the selection of a remediation strategy by presenting all potentially feasible strategies, and how uncertainty on the site's level of contamination affects these strategies.     

Remediation of contaminated lands: a decision methodology for site owners

Deciding how to remediate and redevelop contaminated lands should involve more than just selecting remediation techniques to clean a site to meet regulations for a predetermined site use. Owners and their consultants also need to understand aspects such as alternative site uses and liability, and how issues such as uncertainty can affect them. A methodology has been developed that provides a framework for current site owners when making decisions. It clarifies the above issues and details the type of information that is needed. It offers a step-by-step approach to improve decision making when contemplating remediation of contaminated sites by identifying the site use and remedial action combination that maximizes the current owner's net benefits. It examines various factors in decision making--with special emphasis on the timely issues of liability and uncertainty--and how expert opinion can be used to address diverse or incomplete data. Future research should include developing a complementary methodology that incorporates community and ecological objectives, resulting in a unified decision framework.     

A technicoeconomic approach for the selection of a site remediation strategy--part B: model application

Different tools, such as a screening matrix or decision framework, are available to select a remediation technology to treat a contaminated site. However, unless these methods can point out the appropriate technology in regards to the decision-maker's knowledge about the contaminated site, they are less useful to evaluate both the technical effectiveness and the cost of the remediation, and to assess different remediation strategies from either future data acquisition or the use of an irreversible remediation technology. A model developed to allow such evaluations has been used to simulate the remediation of a virtual contaminated site. From this, four remediation recommendations have been made. These recommendations are guidelines for the build up of a remediation strategy that would both maximize the effectiveness of the decontamination and minimize its total cost.     

The role of science in the decision to site a high-level nuclear waste repository at Yucca Mountain,Nevada, USA

Summary Actions during most of this decade concerning where and how to locate a repository for high-level commercial and defence nuclear wastes have been guided by the National Environmental Policy Act and the Nuclear Waste Policy Act of 1982. Issues of repository siting have been controversial, and in December 1987 Congress passed the Nuclear Waste Policy Amendments Act, which identified Yucca Mountain, Nevada, as the nation's first and only site to be characterized for a potential repository. This decision has generated understudied questions regarding the role of science and ethics derived from the mandates of the legislation and use of environmental impact methodology which is predicated upon a positivistic model of science. Because of the importance of choosing an acceptable repository site to protect humans and natural resources for thousands of years into the future, the broadest spectrum of views and in-depth critiques of the role of science in the repository program is required in order that understudied questions can be resolved.John Lemons is the Chairperson of the Department of Life Sciences at the University of New England and, the Editor-in-Chief of the journalThe Environmental Professional. He has authored numerous articles on nuclear waste management, pollution, and wilderness management.Donald Brown is the Director of the Bureau of Hazardous Sites and Superfund Enforcement for the Commonwealth of Pennsylvania, 221 North Second Street, 3rd Floor, Harrisburg, Pennsylvania 17101. He has published numerous papers on the interface between philosophy and science as it relates to public policy making on environmental issues.     

Risk-based targeting of diffuse contaminant sources at variable spatial scales in a New Zealand high country catchment.

Management of agricultural diffuse pollution requires targeting or prioritising critical source areas at various spatial scales within watersheds. This study develops, evaluates and illustrates a risk-based approach for assessment and targeting of source areas at catchment, subarea and individual farm scales. Catchment water quality data are used in conjunction with information on watershed characteristics from the New Zealand Land Resources Inventory at the subarea scale and land use information at the farm scale to assess risk and target source areas. Total phosphorus in the Lake Hayes Catchment, a high country pastoral catchment in the South Island of New Zealand, is used as a case study. Use, comparison and evaluation of several different methodologies for subareas and individual properties showed that a subarea in the upper catchment and one immediately upstream from the lake were the worst source areas. Targeting of other subareas varied dependent on the method used. The worst individual properties were targeted based on the combination of intensity of cattle and sheep grazing, fertilizer usage, bank erosion and location in the worst subareas. Water quality results are critical to successful targeting, particularly for convincing landowners that streams will benefit from best management practices on their properties. In addition to concentrations, average and extreme loadings are important. Data on catchment characteristics, particularly land use, are needed for targeting, but are not always readily available at small scales. This study demonstrated simple but useful methods for application of assessment information for quantitative targeting of contaminant source areas at different spatial scales.     

Towards a socio‐economic analysis of Scotland's coastal areas

Integrated coastal zone management (ICZM) has evolved as a key mechanism for the delivery of sustainable development objectives within coastal regions. Yet, despite significant advancements in ICZM application over recent years, one of the most noticeable weaknesses of ICZM performance has been a failure to adequately account for the existence of socio‐economic concerns. This information deficiency is particularly apparent in Scotland. Despite significant progress in the promotion of ICZM, Scottish experiences have been characterized by a focus upon sectoral policy co‐ordination and environmental dimensions of sustainability. This paper provides an evaluation of both socio‐economic conditions and processes which impact upon coastal communities in Scotland and considers how such issues can be accounted for within future coastal management debates.     

Alfalfa rapidly remediates excess inorganic nitrogen at a fertilizer spill site

By 19%, standard remediation techniques had significantly reduced the concentration of nitrate nitrogen (NO3- -N) in local ground water at the site of a 1989 anhydrous ammonia spill, but NO3- -N concentrations in portions of the site still exceeded the public drinking water standard. Our objective was to determine whether local soil and ground water quality could be improved with alfalfa (Medicago sativa L.). A 3-yr study was conducted in replicated plots (24 by 30 m) located hydrologically upgradient of the ground water under the spill site. Three alfalfa entries ['Agate', Ineffective Agate (a non-N2-fixing elite germplasm similar to Agate), and MWNC-4 (an experimental germplasm)] were seeded in the spring of 1996. Corn (Zea mays L.) or wheat (Triticum aestivum L.) was seeded adjacent to the alfalfa each year. Crops were irrigated with N-containing ground water to meet water demand. During the 3-yr period, about 540 kg of inorganic N was removed from the aquifer through irrigation of 4.9 million L water. Cumulative N removal from the site over 3 yr was 972 kg N ha(-1) in Ineffective Agate alfalfa hay, compared with 287 kg N ha(-1) for the annual cereal grain. Soil solution NO3- concentrations were reduced to low and stable levels by alfalfa, but were more variable under the annual crops. Ground water quality improved, as evidenced by irrigation water N concentration. We do not know how much N was removed by the N2-fixing alfalfas, but it appears that either fixing or non-N2-fixing alfalfa will effectively remove inorganic N from N-affected sites.     

Solid-state nitrogen-15 nuclear magnetic resonance analysis of biologically reduced 2,4,6-trinitrotoluene in a soil slurry remediation

Soil contaminated with 2,4,6-trinitrotoluene (TNT) and spiked with [14C]- and [15N3]-TNT was subjected to an anaerobic-aerobic soil slurry treatment and subsequently analyzed by radiocounting and solid-state 15N nuclear magnetic resonance (NMR) spectroscopy. This treatment led to a complete disappearance of extractable radioactivity originating from TNT and almost all of the radioactivity was recovered in the insoluble soil fraction. As revealed by solid-state 15N NMR, a major fraction of partially reduced metabolites of TNT was immobilized into the soil during the early stage of the anaerobic treatment, although some of the compounds (i.e., aminodinitrotoluenes and azoxy compounds) were extractable by methanol. Considerable 15N intensity was assigned to condensation products of TNT metabolites. A smaller signal indicated the formation of azoxy N. This signal and the signal for nitro groups were not observed at the end of the anaerobic phase, revealing further reduction and/or transformation of their corresponding compounds. An increase of the relative proportion of the condensation products occurred with increasing anaerobic incubation. Aerobic incubation resulted in a further decrease of aromatic amines, presumably due to oxidative transformations or their involvement in further condensation reactions. The results of the study demonstrate that the anaerobic-aerobic soil slurry treatment represents an efficient strategy for immobilizing reduced TNT in soils.     

Cost‐benefit analysis of soil remediation in Israeli industrial zones

Industrial zones are the main source of soil pollution in Israel. Due to the upcoming approval of the bill on soil contamination and remediation in Israel, it is important to assess the economic feasibility of soil remediation. This study examines the economic feasibility of an extensive remediation project of all contaminated industrial zones in Israel. The estimated economic benefits include both direct benefits, resulting from the increase in the land value of the contaminated site, and indirect benefits, arising from the increase in nearby property values. A cost‐benefit analysis showed a cost benefit ratio of 1:14. Nonetheless, the direct benefits were found to be lower than the costs. Thus, the question of funding requires collaboration between government and the private sector.     

Evaluation of unmitigated options for municipal waste disposal site in Tehran,Iran using an integrated assessment approach

It can be difficult for assessors and decision-makers to compare different options for a project, and thus come to a reasoned and objective decision concerning the impacts and its sustainability at the local level. Therefore, using integrated assessment becomes crucially important for evaluating proposed different options. In this paper, we apply the Rapid Integrated Sustainability Assessment Method (RISAM) to evaluate the proposed unmitigated options for a municipal waste disposal site in Tehran, Iran. The results obtained showed that all of the alternative unmitigated options to the current method of open dumping were indicated as being consistent with very weak sustainability. The RISAM method demonstrated offers potential considerable benefits with respect to improved efficiency, reduced need for resources, and improved consistency and transparency in evaluation and reporting.     

Investment in water infrastructure: Findings from an economic analysis of a national programme

Mixed findings emerge from this ex post Cost-Benefit Analysis of a major water investment programme in Ireland. Water supply and conservation investments, where most benefits were internal, generally proved worthwhile. Wastewater investments could not be analysed fully due to lack of environmental data. Here the authors estimated the level of ‘willingness-to-pay’ that would have been required to ‘justify’ the investments. In some cases the required level seemed implausibly high, raising questions as to prioritisation of projects. The authors recommend a more systematic approach to recording environmental benefits in future investment programmes, the next likely wave being in new EU member states seeking to meet environmental standards. The EU, as likely co-funder of these investments, should require systematic recording of environmental benefits.     

Water transfers,agriculture, and groundwater management: a dynamic economic analysis

Water transfers from agricultural to urban and environmental uses will likely become increasingly common worldwide. Many agricultural areas rely heavily on underlying groundwater aquifers. Out-of-basin surface water transfers will increase aquifer withdrawals while reducing recharge, thereby altering the evolution of the agricultural production/groundwater aquifer system over time. An empirical analysis is conducted for a representative region in California. Transfers via involuntary surface water cutbacks tilt the extraction schedule and lower water table levels and net benefits over time. The effects are large for the water table but more modest for the other variables. Break-even prices are calculated for voluntary quantity contract transfers at the district level. These prices differ considerably from what might be calculated under a static analysis which ignores water table dynamics. Canal-lining implies that districts may gain in the short-run but lose over time if all the reduction in conveyance losses is transferred outside the district. Water markets imply an evolving quantity of exported flows over time and a reduction in basin net benefits under common property usage. Most aquifers underlying major agricultural regions are currently unregulated. Out-of-basin surface water transfers increase stress on the aquifer and management benefits can increase substantially in percentage terms but overall continue to remain small. Conversely, we find that economically efficient management can mitigate some of the adverse consequences of transfers, but not in many circumstances or by much. Management significantly reduced the water table impacts of cutbacks but not annual net benefit impacts. Neither the break-even prices nor the canal-lining impacts were altered by much. The most significant difference is that regional water users gain from water markets under efficient management.     

Initial decision analysis (IDA): a participatory approach for developing resource policies

Initial decision analysis (IDA) is a microcomputer based decision-making technique that is organized so that a rational, step-by-step, procedure can be followed to use existing knowledge to develop resource policies. The IDA process provides a systematic way for participants to define their own problem and to explore jointly alternative solutions. IDA is particularly suited to resolving complex problems involving many groups with conflicting interests. IDA is illustrated with data from the US Forest Service's Draft Environmental Impact Statement for the 1985 to 2030 Resource Planning Act Program for the United States. Four policy options are evaluated: maximization of timber production, of grazing, and of wilderness, and a dominant use policy that concentrates timber management on productive sites. Policies were evaluated using a new mathematical satisficing procedure. Mathematical satisficing of simulated policy consequences showed that, for selected performance standards, current RPA policies are superior to the four alternative policies examined.