Chlorinated vapor intrusion indicators,tracers, and surrogates (ITS): Supplemental measurements for minimizing the number of chemical indoor air samples—Part 1: Vapor intrusion driving forces and related environmental factors

Vapor intrusion (VI) assessment is complicated by spatial and temporal variability, largely due to compounded interactions among the many individual factors that influence the vapor migration pathway from subsurface sources to indoor air. Past research on highly variable indoor air datasets demonstrates that conventional sampling schemes can result in false negative determinations of potential risk corresponding to reasonable maximum exposures (RME). While high‐frequency chemical analysis of individual chlorinated volatile organic compounds (CVOCs) in indoor air is conceptually appealing, it remains largely impractical when numerous buildings are involved and particularly for long‐term monitoring. As more is learned about the challenges with indoor air sampling for VI assessment, it has become clear that alternative approaches are needed to help guide discrete sampling efforts and reduce sampling requirements while maintaining acceptable confidence in exposure characterization. Indicators, tracers, and surrogates (ITS), which include a collection of quantifiable metrics and tools, have been suggested as a potential solution for making VI pathway assessment and long‐term monitoring more informative, efficient, and cost‐effective. This review, compilation, and evaluation of ITS demonstrates how even low numbers of indoor air CVOC samples can provide high levels of confidence for representing the RME levels (e.g., 95th percentile) often sought by regulatory agencies for less than chronic effects. A two‐part compilation of available evidence for select low‐cost ITS is presented, with Part 1 focused on introducing the concepts of ITS, meteorologically based ITS, and the evidence from data‐rich studies to support lower cost CVOC VI assessments. Part 1 includes the results of quantitative analyses on two robust residential building VI datasets, where numerous supplemental metrics were collected concurrently with indoor air concentration data. These are supplemented with additional less‐intensive studies in different circumstances. These analyses show that certain ITS metrics and tools, including differential temperature, differential pressure, and radon (in Part 2), can provide benefits to VI assessment and long‐term monitoring. This includes indicators that narrow the assessment period needed to capture RME conditions, tracers that enhance understanding of the conceptual site model, and aid in the identification of preferential pathways and surrogates that support or substitute for CVOC sampling results. The results of this review provide insight into the scientifically supportable uses of ITS.     

Vapor Intrusion Monitoring Method Cost Comparisons: Automated Continuous Analytical Versus Discrete Time‐Integrated Passive Approaches

Vapor intrusion characterization efforts are challenging due to complexities associated with indoor background sources, preferential subsurface migration pathways, indoor and shallow subsurface concentration dynamics, and representativeness limitations associated with manual monitoring and characterization methods. For sites experiencing trichloroethylene (TCE) vapor intrusion, the potential for acute risks poses additional challenges, as the need for rapid response to acute toxicity threshold exceedances is critical in order to minimize health risks and associated liabilities. Currently accepted discrete time‐integrated vapor intrusion monitoring methods that employ passive diffusion–adsorption and canister samplers often do not result in sufficient temporal or spatial sampling resolution in dynamic settings, have a propensity to yield false negative and false positive results, and are not able to prevent receptors from acute exposure risks, as sample processing times exceed exposure durations of concern. Multiple lines of evidence have been advocated for in an attempt to reduce some of these uncertainties. However, implementation of multiple lines of evidence do not afford rapid response capabilities and typically rely on discrete time‐integrated sample collection methods prone to nonrepresentative results due to concentration dynamics. Recent technology innovations have resulted in the deployment of continuous monitoring platforms composed of multiplexed laboratory grade analytical components integrated with quality control features, telemetry, geographical information systems, and interpolation algorithms for automatically generating geospatial time stamped renderings and time‐weighted averages through a cloud‐based data management platform. Automated alerts and responses can be engaged within 1 minute of a threshold exceedance detection. Superior temporal and spatial resolution also results in optimized remediation design and mitigation system performance confirmation. While continuous monitoring has been acknowledged by the regulatory community as a viable option for providing superior results when addressing spatial and temporal dynamics, until very recently, these approaches have been considered impractical due to cost constraints and instrumentation limitations. Recent instrumentation advancements via automation and multiplexing allow for rapid and continuous assessment and response from multiple locations using a single instrument. These advancements have reduced costs to the point where they are now competitive with discrete time‐integrated methods. In order to gain more regulatory and industry support for these viable options, there is an immediate need to perform a realistic cost comparison between currently approved discrete time‐integrated methods and newly fielded continuous monitoring platforms. Regulatory support for continuous monitoring platforms will result in more effectively protecting the public, provide property owners with information sufficient to more accurately address potential liabilities, reduce unnecessary remediation costs for situations where risks are minimal, lead to more effective and surgical remediation strategies, and allow practitioners to most effectively evaluate remediation system performance. To address this need, a series of common monitoring scenarios and associated assumptions were derived and cost comparisons performed. Scenarios included variables such as number of monitoring locations, duration, costs to meet quality control requirements, and number of analyses performed within a given monitoring campaign. Results from this effort suggest that for relatively larger sites where five or more locations will be monitored (e.g., large buildings, multistructure industrial complexes, educational facilities, or shallow groundwater plumes with significant spatial footprints under residential neighborhoods), procurement of continuous monitoring services is often less expensive than implementation of discrete time‐integrated monitoring services. For instance, for a 1‐week monitoring campaign, costs‐per‐analysis for continuous monitoring ranges from approximately 1 to 3 percent of discrete time‐integrated method costs for the scenarios investigated. Over this same one‐week duration, for discrete time‐integrated options, the number of sample analyses equals the number of data collection points (which ranged from 5 to 30 for this effort). In contrast, the number of analyses per week for the continuous monitoring option equals 672, or four analyses per hour. This investigation also suggests that continuous automated monitoring can be cost‐effective for multiple one‐week campaigns on a quarterly or semi‐annual basis in lieu of discrete time‐integrated monitoring options. In addition to cost benefits, automated responses are embedded within the continuous monitoring service and, therefore, provide acute TCE risk‐preventative capabilities that are not possible using discrete time‐integrated passive sampling methods, as the discrete time‐integrated services include analytical efforts that require more time than the exposure duration of concern. ©2016 Wiley Periodicals, Inc.     

An evaluation of the performance of multiple passive diffusion devices for indoor air sampling of VOCs

The United States Environmental Protection Agency is considering recommending longer‐term sampling to achieve more accurate time‐weighted‐average detections for indoor air monitoring of volatile organic chemicals. The purpose of the research presented herein was to compare longer sampling times using passive diffusion samplers to the results from shorter‐term testing periods using sorbent tubes and low‐flow pumps (US EPA Method TO‐17) at great frequency for trichloroethene (TCE) in indoor air. A controlled release of TCE in a large room allowed for over two‐orders‐of‐magnitude daily concentration variability over the course of the two‐week monitoring event. The daily concentration measurements by US EPA Method TO‐17 and the passive diffusion samplers were performed in triplicate and had excellent reproducibility. The results of daily tests were averaged and compared with four passive diffusion devices exposed to indoor air for three, seven, ten, and fourteen days in accordance with ASTM D6196‐02. A specific uptake rate for each of the passive devices at the four different time intervals and the statistical significance of the time‐varying uptake rates were evaluated. The performance of each passive diffusion device was determined using a statistical performance criterion. The average concentration for all of the exposure periods could be reliably predicted using the established uptake rates for two of the four passive devices. © 2009 Wiley Periodicals, Inc.     

Residential vapor‐intrusion evaluation: Long‐duration passive sampling vs. short‐duration active sampling

Sampling indoor air for potential vapor‐intrusion impacts using current standard 24‐hour sample collection methods may not adequately account for temporal variability and detect contamination best represented by long‐term sampling periods. Henry Schuver of the U.S. Environmental Protection Agency Office of Solid Waste stated at the September 2007 Air & Waste Management Association vapor‐intrusion conference that the US EPA may consider recommending longer‐term vapor sampling to achieve more accurate time‐weighted‐average detections. In November 2007, indoor air at four residences was sampled to measure trichloroethene (TCE) concentrations over short‐ and long‐duration intervals. A carefully designed investigation was conducted consisting of triplicate samplers for three different investigatory methods: dedicated 6‐liter Summa canisters (US EPA Method TO‐15), pump/sorbent tubes (US EPA Method TO‐17), and passive diffusion samplers (MDHS 80). The first two methods collected samples simultaneously for a 24‐hour period, and the third method collected samples for two weeks. Data collected using Methods TO‐15 (canisters) and TO‐17 (tubes) provided reliable short‐duration TCE concentrations that agree with prior 24‐hour sampling events in each of the residences; however, the passive diffusion samplers may provide a more representative time‐weighted measurement. The ratio of measured TCE concentrations between the canisters and tubes are consistent with previous results and as much as 28.0 μg/m³ were measured. A comparison of the sampling procedures, and findings of the three methods used in this study will be presented. © 2008 Wiley Periodicals, Inc.     

Radiological risks and cleanup costs: A remediation case study

Potential health risks and cleanup costs are primary factors for measuring the effectiveness of a remediation project concerning a site contaminated with residual radioactive materials. Demanding cleanup of a contaminated site to its original condition, while eliminating any health risks after cleanup, can require prohibitive costs. However, by setting practical remediation objectives and by performing realistic but conservative risk assessments, health risks can be acceptable and cleanup costs can be reasonable. This article uses the South-Middle and Southeast Vaults Decontamination and Demolition Project at Argonne National Laboratory to demonstrate how negligible health risks can result after cleanup with minimal cleanup costs. Substantial cost savings of approximately $2 million was realized by implementing in-place decontamination and demolition (D&D) on the basis of acceptable risk, instead of requiring cleanup of the site to its original condition. By using the RESRAD computer program as a modeling tool, we show the maximum projected radiation dose (0.1 mrem per year) and the potential lifetime cancer risk (on the order of 10⁶) to an individual from exposure to the residual radioactivities are negligibly small. In addition to aiding in the selection of a preferred remediation alternative, results of the RESRAD modeling were also used to guide the implementation of the selected alternative to reduce exposures from the dominant pathway and to ensure that exposures from all pathways would be as low as reasonably achievable.     

MULTI INCREMENT® TCE vadose‐zone investigation

MULTI INCREMENT® and discrete sampling strategies were used to estimate the average concentration and the three‐dimensional distribution of TCE in a 3,300‐m³ zone composed of two decision units (e.g., area of concern, population, exposure unit). Authors of this article and a private contractor (Stanley Consultants Inc.), respectively, implemented these two sampling strategies independently. Compared to discrete sampling, the MULTI INCREMENT sampling strategy identified more locations where percent‐level concentrations of TCE have migrated, is more economical, and provided greater data quality. © 2008 Wiley Periodicals, Inc.     

Ambient levels of PFOS and PFOA in multiple environmental media

Making remediation and risk management decisions for widely‐distributed chemicals is a challenging aspect of contaminated site management. The objective of this study is to present an initial evaluation of the ubiquitous, ambient environmental distribution of poly‐ and perfluoroalkyl substances (PFAS) within the context of environmental decision‐making at contaminated sites. PFAS are anthropogenic contaminants of emerging concern with a wide variety of consumer and industrial sources and uses that result in multiple exposure routes for humans. The combination of widespread prevalence and low screening levels introduces considerable uncertainty and potential costs in the environmental management of PFAS. PFAS are not naturally‐occurring, but are frequently detected in environmental media independent of site‐specific (i.e., point source) contamination. Information was collected on background and ambient levels of two predominant PFAS, perfluorooctane sulfonate and perfluorooctanoate, in North America in both abiotic media (soil, sediment, surface water, and public drinking water supplies) and selected biotic media (human tissues, fish, and shellfish). The background or ambient information was compiled from multiple published sources, organized by medium and concentration ranges, and evaluated for geographical trends and, when available, also compared to health‐based screening levels. Data coverage and quality varied from wide‐ranging and well‐documented for soil, surface water, and serum data to more localized and less well‐documented for sediment and fish and shellfish tissues and some uncertainties in the data were noted. Widespread ambient soil and sediment concentrations were noted but were well below human health‐protective thresholds for direct contact exposures. Surface water, drinking water supply waters (representing a combination of groundwater and surface water), fish and shellfish tissue, and human serum levels ranged from less than to greater than available health‐based threshold values. This evaluation highlights the need for incorporating literature‐based or site‐specific background into PFAS site evaluation and decision‐making, so that source identification, risk management, and remediation goals are properly focused and to also inform general policy development for PFAS management.     

Application of passive soil gas technology to determine the source and extent of a PCE groundwater plume in an urban environment

In situations where groundwater supplies have been impacted by volatile organic compounds (VOCs), such as tetrachloroethene (PCE), and the source has not been identified, the costs to identify the source and plume migration patterns may be extremely high. The costs for an investigation increase with the number and depth of borings and the number of samples that are collected and analyzed. An environmental investigator and the Arizona Department of Environmental Quality (ADEQ) have successfully utilized passive soil gas (PSG) surveys in Arizona to cost‐effectively investigate VOC impacts to groundwater and identify potential sources of impact. PSG surveys are minimally intrusive, and more samples can be collected for the same cost when compared to active soil gas surveys and conventional soil and groundwater sampling programs. The result is a surficial representation of the contaminant plume and the location of “hot spots,'' which are the potential sources. This provides a better understanding of the nature and extent of the impact and allows for a focused subsurface investigation, which subsequently reduces drilling and sampling costs. © 2008 Wiley Periodicals, Inc.     

Adaptive sampling and analysis programs for contaminated soils

Adaptive sampling and analysis programs (ASAPs) provide a cost-effective alternative to traditional sampling program designs. ASAPs are based on field analytical methods for rapid sample turnaround and field-based decision support for guiding the progress of the sampling program. One common objective of ASAPs is to delineate contamination present in soils, either to support feasibility studies or remedial action designs. An ASAP based on portable gas chromatograph/ mass spectrograph (GC/MS) technologies developed at Tufts University combined with decision support tools created at Argonne National Laboratory was used to delineate explosives contamination in soils at Joliet Army Ammunition Plant, Joliet, Illinois. Tufts' GC/MS technologies provided contaminant-specific identification and quantification with rapid sample turnaround and high sample throughput. Argonne's decision support tools estimated contamination extent, determined the uncertainty associated with those estimates, and indicated where sampling should continue to minimize uncertainty. In the case of Joliet, per sample analytical costs were reduced by 75 percent as compared to the cost of off-site laboratory analyses for explosives. The use of an ASAP resulted in a much more accurate identification and delineation of contaminated areas than a traditional sampling program would have with the same number of samples collected on a regular grid. While targeting explosives contamination in soils at Joliet, the ASAP technologies used in this demonstration have much broader application.     

Choosing remediation and waste management options at hazardous and radioactive waste sites

This article discusses a process for finding insights that will allow federal agencies and environmental professionals to more effectively manage contaminated sites. The process is built around what Etzioni (1968) called mixed‐scanning, that is, perpetually doing both comprehensive and detailed analyses and periodically re‐scanning for new circumstances that change the decision‐making environment. The article offers a checklist of 127 items, which is one part of the multiple‐stage scanning process. The checklist includes questions about technology; public, worker, and ecological health; economic cost and benefits; social impacts; and legal issues. While developed for a DOE high‐level radioactive waste application, the decision‐making framework and specific questions can be used for other large‐scale remediation and management projects. © 2002 Wiley Periodicals, Inc.     

Mitigation of methane emission from an old unlined landfill in Klintholm,Denmark using a passive biocover system

Methane generated at landfills contributes to global warming and can be mitigated by biocover systems relying on microbial methane oxidation. As part of a closure plan for an old unlined landfill without any gas management measures, an innovative biocover system was established. The system was designed based on a conceptual model of the gas emission patterns established through an initial baseline study. The study included construction of gas collection trenches along the slopes of the landfill where the majority of the methane emissions occurred. Local compost materials were tested as to their usefulness as bioactive methane oxidizing material and a suitable compost mixture was selected. Whole site methane emission quantifications based on combined tracer release and downwind measurements in combination with several local experimental activities (gas composition within biocover layers, flux chamber based emission measurements and logging of compost temperatures) proved that the biocover system had an average mitigation efficiency of approximately 80%. The study showed that the system also had a high efficiency during winter periods with temperatures below freezing. An economic analysis indicated that the mitigation costs of the biocover system were competitive to other existing greenhouse gas mitigation options.     

Addressing soil gas vapor intrusion using sustainable building solutions

Soil gas vapor intrusion (VI) emerged in the 1990s as one of the most important problems in the investigation and cleanup of thousands of sites across the United States. A common practice for sites where VI has been determined to be a significant pathway is to implement interim building engineering controls to mitigate exposure of building occupants to VI while the source of contamination in underlying soil and groundwater is assessed and remediated. Engineering controls may include passive barriers, passive or active venting, subslab depressurization, building pressurization, and sealing the building envelope. Another recent trend is the emphasis on “green” building practices, which coincidentally incorporate some of these same engineering controls, as well as other measures such as increased ventilation and building commissioning for energy conservation and indoor air quality. These green building practices can also be used as components of VI solutions. This article evaluates the sustainability of engineering controls in solving VI problems, both in terms of long‐term effectiveness and “green” attributes. Long‐term effectiveness is inferred from extensive experience using similar engineering controls to mitigate intrusion of radon, moisture, mold, and methane into structures. Studies are needed to confirm that engineering controls to prevent VI can have similar long‐term effectiveness. This article demonstrates that using engineering controls to prevent VI is “green” in accelerating redevelopment of contaminated sites, improving indoor air quality, and minimizing material use, energy consumption, greenhouse gas emissions, and waste generation. It is anticipated that engineering controls can be used successfully as sustainable solutions to VI problems at some sites, such as those deemed technically impracticable to clean up, where remediation of underlying soil or groundwater contamination will not be completed in the foreseeable future. Furthermore, green buildings to be developed in areas of potential soil or groundwater contamination may be designed to incorporate engineering controls to prevent VI. © 2009 Wiley Periodicals, Inc.     

Expediting sustainable brownfields redevelopment by applying Triad using the membrane interface probe

Redevelopment and reuse plans are often based upon an expedited delineation and remediation life cycle, since delayed reuse usually has economic consequences. It has also become increasingly important to utilize sustainable practices to achieve investigation and remediation goals. In this article, the Triad approach is used to expedite the delineation of a source area within a municipal landfill to complete the remedial effort prior to construction of an urban civic center. The Triad approach uses the three elements of systematic project planning, dynamic work strategy, and real‐time measurement to expedite site characterization (Interstate Technology and Regulatory Council, 2003). In this article, the Triad sampling strategy consisted of two phases. The first phase included in situ screening of soil and groundwater using the membrane interface probe (MIP), and the second phase included confirmatory sampling via vertical profiles in the soil and groundwater. This study found that, using the MIP in a dynamic sampling strategy, a critical element of the Triad approach, combined with the proper placement of confirmatory samples, significantly reduced overall project cost and will expedite the site redevelopment. The use of the Triad approach also contributed to the integration of green and sustainable practices into the project. © 2010 Wiley Periodicals, Inc.     

Economic Project Risk Assessment in Remediation Projects Prior to Construction: Methodology Development and Case Study Application

Probabilistic economic analysis, including uncertainty of probabilities and consequences of project risks, is not widely used in remediation projects. This article presents a project risk assessment (PRA) method to identify, quantify, and analyze risks in remediation projects. The suggested method is probabilistic and includes uncertainty analysis of input variables based on expert judgment. It was originally developed as a part of a sustainability assessment tool, but is viable as a stand‐alone tool for remediation projects. The method is applied to a case study: a former paint factory that is being redeveloped into a residential area. The PRA method is used for analyzing and comparing the project risks associated with four remediation options, all including excavation but with different degrees of onsite treatment. The result of the case study application shows which alternative has the lowest mean risk cost, the highest probability to have the lowest risk cost, and how the risk costs are distributed, but also, importantly, helps the user to prioritize between risk‐reduction measures. ©2015 Wiley Periodicals     

Using multivariate regression modeling for sampling and predicting chemical characteristics of mixed waste in old landfills

Municipal solid waste landfills pose a threat on environment and human health, especially old landfills which lack facilities for collection and treatment of landfill gas and leachate. Consequently, missing information about emission flows prevent site-specific environmental risk assessments. To overcome this gap, the combination of waste sampling and analysis with statistical modeling is one option for estimating present and future emission potentials. Optimizing the tradeoff between investigation costs and reliable results requires knowledge about both: the number of samples to be taken and variables to be analyzed.This article aims to identify the optimized number of waste samples and variables in order to predict a larger set of variables. Therefore, we introduce a multivariate linear regression model and tested the applicability by usage of two case studies. Landfill A was used to set up and calibrate the model based on 50 waste samples and twelve variables. The calibrated model was applied to Landfill B including 36 waste samples and twelve variables with four predictor variables.The case study results are twofold: first, the reliable and accurate prediction of the twelve variables can be achieved with the knowledge of four predictor variables (Loi, EC, pH and Cl). For the second Landfill B, only ten full measurements would be needed for a reliable prediction of most response variables. The four predictor variables would exhibit comparably low analytical costs in comparison to the full set of measurements. This cost reduction could be used to increase the number of samples yielding an improved understanding of the spatial waste heterogeneity in landfills.Concluding, the future application of the developed model potentially improves the reliability of predicted emission potentials. The model could become a standard screening tool for old landfills if its applicability and reliability would be tested in additional case studies.     

Vapor intrusion risk evaluation using automated continuous chemical and physical parameter monitoring

Vapor intrusion risk characterization efforts are challenging due to complexities associated with background indoor air constituents, preferential subsurface migration pathways, and representativeness limitations associated with traditional randomly timed time‐integrated sampling methods that do not sufficiently account for factors controlling concentration dynamics. The U.S. Environmental Protection Agency recommends basing risk related decisions on the reasonable maximum exposure (RME). However, with very few exceptions, practitioners have not been applying this criterion. The RME will most likely occur during upward advective flux conditions. As such, for RME determinations, it is important to sample when upward advective flux conditions are occurring. The most common vapor intrusion assessment efforts include randomly timed sample collection events, and therefore do not accurately yield RME estimates. More specifically, researchers have demonstrated that randomly timed sampling schemes can result in false negative determinations of potential risk corresponding to RMEs. For sites experiencing trichloroethylene (TCE) vapor intrusion, the potential for acute risks poses additional challenges, as there is a critical need for rapid response to exposure exceedances to minimize health risks and liabilities. To address these challenges, continuous monitoring platforms have been deployed to monitor indoor concentrations of key volatile constituents, atmospheric pressure, and pressure differential conditions that can result in upward toxic vapor transport and entry into overlying buildings. This article demonstrates how vapor intrusion RME‐based risks can be successfully and efficiently determined using continuous monitoring of concentration and parameters indicating upward advective chemical flux. Time series analyses from multiple selected 8‐ and 24‐hr time increments during upward advective TCE flux conditions were performed to simulate results expected from the most commonly employed sampling methods. These analyses indicate that, although most of the selected time increments overlap within the same 24‐hr window, results and conclusions vary. As such, these findings demonstrate that continuous monitoring of concentration and parameters such as differential pressure and determination of a time‐weighted concentration average over a selected duration when upward advective flux is occurring can allow for a realistic RME‐based risk estimate.     

Waste collection systems for recyclables: An environmental and economic assessment for the municipality of Aarhus (Denmark)

Recycling of paper and glass from household waste is an integrated part of waste management in Denmark, however, increased recycling is a legislative target. The questions are: how much more can the recycling rate be increased through improvements of collection schemes when organisational and technical limitations are respected, and what will the environmental and economic consequences be? This was investigated in a case study of a municipal waste management system. Five scenarios with alternative collection systems for recyclables (paper, glass, metal and plastic packaging) were assessed by means of a life cycle assessment and an assessment of the municipality’s costs. Kerbside collection would provide the highest recycling rate, 31% compared to 25% in the baseline scenario, but bring schemes with drop-off containers would also be a reasonable solution. Collection of recyclables at recycling centres was not recommendable because the recycling rate would decrease to 20%. In general, the results showed that enhancing recycling and avoiding incineration was recommendable because the environmental performance was improved in several impact categories. The municipal costs for collection and treatment of waste were reduced with increasing recycling, mainly because the high cost for incineration was avoided. However, solutions for mitigation of air pollution caused by increased collection and transport should be sought.     

Sustainable Remediation and Decision Analysis Practices at an Onshore Gas Well Site

Strategies for remediation of drilling mud wastes at a typical deep sour gas well site in the foothills of Alberta were assessed in terms of financial and social costs and benefits, in alignment with established sustainable remediation and decision analysis principles. Managers of contaminated sites containing historical drilling wastes are challenged with managing liability through several regulatory changes over time. Excavation and disposal of the contaminated soil from the site was the only means of securing regulatory release, with the nearest landfill located 150 km away. A perception exists that in many cases excavation and disposal inflicts unnecessary levels of site intrusiveness and public disturbance when other options achieving a similar risk end point may do so for lower social cost. The study tested this hypothesis to ascertain whether the currently accepted solution is the best option when the wider costs and benefits to society and the environment are included. Eight remedial strategies were assessed using cost–benefit analysis, including using environmental economics techniques to quantify social and environmental impacts. The economic model showed that methods such as capping in‐place or engineered encapsulation were superior to full excavation and disposal from financial and sustainability perspectives. Quantified external costs and benefits such as road damage, greenhouse gas emissions, public nuisance and safety, and community amenity value were influential in identifying superior options. It was demonstrated that $0.2 million of societal costs could be avoided by choosing capping over landfill disposal. This represents substantial implications when viewed in the context of this and other operators’ portfolios of hundreds of abandoned wells in the area. ©2016 Wiley Periodicals, Inc.     

Evaluating the Triple Bottom Line Using Sustainable Return on Investment

A sustainable return on investment (sROI) analysis is a quantitative approach that captures the economic, environmental, and social impacts of an investment strategy in monetary terms—today and into the future. By providing a broader accounting of the benefits and costs, sROI provides a framework for optimal decision making. sROI is a nonproprietary methodology based on economic principles and includes an uncertainty analysis to demonstrate the likelihood of realizing costs and benefits. This approach provides a more comprehensive picture of projects and supports the selection of investment strategies that are defensible and transparent. sROI can provide the framework and metrics for the evaluation and selection of remediation projects. A demonstration study of a DuPont remediation project illustrates the process and outcome of an sROI analysis. © 2014 Wiley Periodicals, Inc.     

Developing Effective Decision Support for the Application of “Gentle” Remediation Options: The GREENLAND Project

Gentle remediation options (GRO) are risk management strategies/technologies that result in a net gain (or at least no gross reduction) in soil function as well as risk management. They encompass a number of technologies, including the use of plant (phyto‐), fungi (myco‐), and/or bacteria‐based methods, with or without chemical soil additives or amendments, for reducing contaminant transfer to local receptors by in situ stabilization, or extraction, transformation, or degradation of contaminants. Despite offering strong benefits in terms of risk management, deployment costs, and sustainability for a range of site problems, the application of GRO as practical on‐site remedial solutions is still in its relative infancy, particularly for metal(loid)‐contaminated sites. A key barrier to wider adoption of GRO relates to general uncertainties and lack of stakeholder confidence in (and indeed knowledge of) the feasibility or reliability of GRO as practical risk management solutions. The GREENLAND project has therefore developed a simple and transparent decision support framework for promoting the appropriate use of gentle remediation options and encouraging participation of stakeholders, supplemented by a set of specific design aids for use when GRO appear to be a viable option. The framework is presented as a three phased model or Decision Support Tool (DST), in the form of a Microsoft Excel‐based workbook, designed to inform decision‐making and options appraisal during the selection of remedial approaches for contaminated sites. The DST acts as a simple decision support and stakeholder engagement tool for the application of GRO, providing a context for GRO application (particularly where soft end‐use of remediated land is envisaged), quick reference tables (including an economic cost calculator), and supporting information and technical guidance drawing on practical examples of effective GRO application at trace metal(loid) contaminated sites across Europe. This article introduces the decision support framework. ©2015 Wiley Periodicals, Inc.