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As the environmental remediation industry matures, remaining sites often have significant underlying technical challenges and financial constraints. More often than not, significant remediation efforts at these “complex” sites have not achieved stringent, promulgated cleanup goals. Decisions then have to be made about whether and how to commit additional resources towards achieving those goals, which are often not achievable nor required to protect receptors. Guidance on cleanup approaches focused on evaluating and managing site-specific conditions and risks, rather than uniformly meeting contaminant cleanup criteria in all media, is available to aid in this decision. Although these risk-based cleanup approaches, such as alternative endpoints and adaptive management strategies, have been developed, they are under-utilized due to environmental, socio-economic, and risk perception barriers. Also, these approaches are usually implemented late in the project life cycle after unsuccessful remedial attempts to achieve stringent cleanup criteria. In this article, we address these barriers by developing an early decision framework to identify if site characteristics support sustainable risk management, and develop performance metrics and tools to evaluate and implement successful risk-based cleanup approaches. In addition, we address uncertainty and risk perception challenges by aligning risk-based cleanup approaches with the concepts of risk management and sustainable remediation. This approach was developed in the context of lessons learned from implementing remediation at complex sites, but as a framework can, and should, be applied to all sites undergoing remediation. [ABSTRACT FROM AUTHOR]

Stakeholder engagement is a vital sustainable remediation practice for obtaining useful feedback and identifying societal needs. Evaluating and integrating risk perception of stakeholders into remediation and outreach efforts allows for greater insight, increases the likelihood of success and ultimately, benefits the community by protecting its members from environmental hazards. In this study, we identified risk perception factors that influenced residents' level of concern for mitigating their exposure to elevated concentrations of lead in household paint and historic fill material. Risk perception factors were assessed by an in-person survey conducted in public green spaces. The analysis of survey participants’ responses indicated that their perception of risk to exposed lead was mostly influenced by the presence of hazardous materials in close proximity to their residence, the ability to address pollution, and awareness, interest, and individual accountability in mitigating environmental risks. Responses also revealed that residents considered risk of lead and soil pollution as less menacing than the presence of more immediate and perceptible risks posed by factors such as air and water pollution. In addition, the community seemed to exhibit “optimism bias” and did not identify itself at high risk to susceptible and immediate hazards, including lead exposure. This lack of concern over lead exposure created a significant obstacle to community participation in state-led education and outreach programs. By integrating risk perception analysis and increasing stakeholder engagement, we can bring more attention to this issue, educate the public about the threat of lead pollution, and efficiently use financial resources to implement a more sustainable solution. [ABSTRACT FROM AUTHOR]

Environmental remediation activities often require the management of large volumes of water and the consumption of significant amounts of local natural resources, including energy and fossil fuels. Traditionally, proposed remedial approaches for a specific cleanup scenario are evaluated by overall project implementation cost, time frame of the cleanup, and effectiveness to meet cleanup goals. A new paradigm shift, referred to as sustainable remediation, has influenced the remediation industry to consider environmental, social, and economic impacts from cleanup activities. An environmental footprint analysis is the most common method to evaluate environmental implications of cleanup approaches. Presently, these footprint tools do not associate the environmental implications with global impacts. In this article, the method has been extended to integrate the social cost of carbon emissions to quantify global impacts. The case study site is a former aircraft parts manufacturing facility that caused chlorinated solvent contamination in soil and groundwater beneath the building. A groundwater pump-and-treat system was initially installed, followed by its gradual phase-out with concurrent phase in of in situ bioremediation. The case study evaluates the monetized societal benefits from quantifying carbon emission impacts of the proposed cleanup approaches and alternative scenarios. Our results suggest that societal impacts based on monetized carbon emissions can be reduced by 27% by optimizing the remediation processes. The sensitivity analysis results elucidate how variation in carbon prices and social discount rates can influence cleanup decisions for remediation projects. [ABSTRACT FROM AUTHOR]

The use of the anaerobic membrane bioreactor (AnMBR) process for domestic wastewater treatment presents an opportunity to mitigate environmental, social, and economic impacts currently incurred from energy-intensive conventional aerobic activated sludge processes. Previous studies have performed detailed evaluations on improving AnMBR process subcomponents to maximize energy recovery and dissolved methane recovery. Few studies have broadly evaluated the role of chemical use, membrane fouling management, and dissolved methane removal technologies. A life cycle assessment was conducted to holistically compare multiple AnMBR-based domestic wastewater treatment trains to conventional activated sludge (CAS) treatment. These treatment trains included different scouring methods to mitigate membrane fouling (gas-sparging and granular activated carbon-fluidizing) with consideration of upstream treatment (primary sedimentation vs. screening only), downstream treatment (dissolved methane removal and nutrient removal) and sludge management (anaerobic digestion and lime stabilization). This study determined two process subcomponents (sulfide and phosphorus removal and sludge management) that drove chemical use and residuals generation, and in turn the environmental and cost impacts. Furthermore, integrating primary sedimentation and a vacuum degassing tank for dissolved methane removal maximized net energy recovery. Sustainability impacts were further mitigated by operating at a higher flux and temperature, as well as by substituting biological sulfide removal for chemical coagulation. Image 1 • Chemical use is a major environmental impact and cost driver of sulfide removal. • Alternative biological sulfide removal can mitigate chemical use impacts. • Primary treatment and vacuum flash tank for dissolved methane removal reduce impacts. • Potential exists for AnMBR to be more sustainable than conventional treatment. [ABSTRACT FROM AUTHOR]

Under the Paris Agreement, nations and cities are under increasing pressure to reduce greenhouse gas (GHG) emission. Brownfield land redevelopment promises climate change mitigation benefits; however, no studies have attempted to quantify the mitigation potential on a city level. Here we propose a method for this purpose. The method is based on life cycle assessment of GHG emission as compared to greenfield land development, in three categories: (1) primary impact (associated with physical state of brownfield sites and greenfield sites), (2) secondary impact (associated with remediation activities at brownfield sites), and (3) tertiary impact (associated with post-remediation usage of the brownfield sites and avoided usage of greenfield land). A quantitative assessment was conducted for the city of San Francisco in the US, a growing city with ambitious carbon reduction plans. City wide contaminated land remediation activities were found to render a significant secondary impact, resulting in increased GHG emission of 3.54 Mt CO 2 eq. However, by averting the development of greenfield land, this negative impact was partially off-set by a primary impact reduction of 1.22 Mt CO 2 eq. Moreover, the redevelopment of brownfield land offers large tertiary impact reductions due to higher housing density, less utility and road construction needs, shorter commute distances, and smaller household energy consumption. Overall, the results show that brownfield land redevelopment led to a net GHG reduction of 51.9 Mt CO 2 eq. over a 70-year period, or 0.74 Mt CO 2 yr −1 , the equivalent of 14% of San Francisco's 5.3 Mt CO 2 eq. GHG emission in 2010. It was found that reduced household electricity and space heating energy consumption and shorter commute distances were the main contributors, accounting for 41.2% and 34.0% of the tertiary impact reduction, respectively. While it is not expected that all cities can fully capture these climate change mitigation benefits, the present study demonstrates a quantification method and emphasizes the large climate change mitigation potential associated with brownfield land redevelopment. Progression of this premise will require regulators and policy makers to better align cities' climate change mitigation strategies with urban planning and development actions. [ABSTRACT FROM AUTHOR]

Since mid-to-late 2000s growing interest for sustainable remediation has emerged in initiatives from several international and national organisations as well as other initiatives from networks and forums. This reflects a realisation that risk-management activities can about bring environmental, social, and economic impacts (positive or negative) in addition to achieving risk-based remediation goals. These ideas have begun to develop as a new discipline of “sustainable remediation”. The various initiatives have now published a number of frameworks, standards, white papers, road maps and operative guidelines. The similarities and differences in the approaches by these outputs and general trends have been identified. The comparison is based on a set of criteria developed in discussion with members of these various initiatives, and identifies a range of similarities between their publications. Overall the comparison demonstrates a high level of consensus across definitions and principles, which leads to the conclusion that there is a shared understanding of what sustainable remediation is both across countries and stakeholder groups. Publications do differ in points of detail, in particular about the operational aspects of sustainable remediation assessment. These differences likely result from differences in context and legal framework. As this analysis was carried out its findings were debated with members of the various international initiatives, many of whom have been included as authors. Hence the outcomes described in this paper can be seen as the result of a sort of multi-level debate among international experts (authors) and so can offer a starting point to new sustainable remediation initiatives (for example in other countries) that aim to start developing their own documents. [ABSTRACT FROM AUTHOR]