the 26th international conference on solid waste ...the 26th international conference on solid waste...

The 26th International Conference on Solid Waste Technology and Management

March 27 – 30, 2011 Philadelphia, PA U.S.A.

Iraj Zandi, Founder Ronald L. Mersky, Chair

Wen K. Shieh, Associate Chair

The Journal of Solid Waste Technology and Management Department of Civil Engineering, Widener University 1 University Place, Chester, PA 19013-5792 U.S.A.

Phone: 610-499-4042 Fax: 610-499-4461 Email: [email protected]

Web: www.widener.edu/solidwaste

ISSN 1091-8043 © 2011 Journal of Solid Waste Technology and Management

The responsibility for contents rests upon the authors and not upon JSWTM or Widener University.

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____________________________________________________________________________________________ Proceedings of the 26th International Conference on Solid Waste Technology and Management, Philadelphia, PA, U.S.A., March 27 - 30, 2011

Green and Sustainable Remediation

Krishna R. Reddy, Ph.D., P.E. Professor of Civil & Environmental Engineering,

University of Illinois at Chicago, Department of Civil & Materials Engineering, 842 West Taylor Street, Chicago, Illinois 60607, USA

e-mail: [email protected]

Abstract: Traditional remediation approaches often focus on reducing the contaminant levels to the risk-based levels at low cost in a short period of time. In contrast to a traditional remediation approach, green and sustainable remediation (GSR) is a holistic approach to remediation that also minimizes ancillary environmental impacts. The GSR approach addresses a broad range of environmental factors and community impacts during all remediation phases. The objectives of GSR aim to achieve remedial goals through more efficient, sustainable strategies that conserve resources and protect air, water, and soil quality through reduced emissions and other waste burdens. GSR also simultaneously encourages the reuse of remediated land and increased long-term financial returns for investments. Ultimately, the GSR approach strives to maximize the environmental, social and economic benefits (often known as triple bottom line) associated with a project. Though the potential benefits of GSR are enormous, many environmental professionals and project stakeholders do not utilize GSR technologies because they are unaware of methods for selection and implementation. However, with continued public awareness of sustainability issues, GSR will increasingly be pursued. This study provides an overview of the elements of GSR, a review of initiatives to foster GSR best management practices, a summary of metrics to assess the sustainability of GSR, and a review of selected case studies that highlight the net environmental, economic, and societal benefits of incorporating GSR for site restoration. Introduction There are numerous sites contaminated with toxic chemicals worldwide and require remediation to protect public health and the environment. As per the United States Environmental Protection Agency (USEPA), there are over 217,000 sites contaminated with a wide range of organic and heavy metal contaminants across the United States which require urgent remediation, and the cost of remediation of these sites is estimated to exceed over 300 billion dollars. Risk-based remediation approaches are used to calculate the remedial goals that can reduce the human and ecological risks to the acceptable levels. Several in-situ and ex-situ remediation technologies have been developed to achieve the remedial goals. The ex-situ soil remediation technologies include soil washing, chemical oxidation/reduction, stabilization/solidification, thermal desorption, vitrification, electrokinetics, and bioremediation. The in-situ soil remediation technologies include soil vapor extraction, soil flushing, chemical oxidation/reduction, thermal desorption, vitrification, electrokinetics, bioremediation, and phytoremediation. In addition to the adaptation of select in-situ soil remediation technologies, groundwater can be remediated using other in-situ methods such as pump-and-treat (mainly for the source removal), air sparging, permeable reactive barriers, etc.

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The details on the risk assessment methodologies and different soil and groundwater technologies can be found in Sharma and Reddy (2004). Traditional risk-based site remedial approach is based on: (1) the effectiveness and appropriateness of the particular remediation method to meet the remedial goals; (2) ease of implementation; (3) remediation costs; and (4) remediation timeframe. Such approach is not always sustainable because it does not account for broader environmental impacts such as extraction and use of natural resources, wastes created, and energy use and related greenhouse gas (GHG) emissions for on and off-site operations and transportation of equipment and materials to and from site. Thus, the current approach does not explicitly account for the net environmental benefit when all relevant environmental parameters are considered. To address this, green and sustainable remediation (GSR) approach has emerged recently. This paper presents the definition and core elements of GSR followed by GSR decision framework that addresses sustainability metrics and assessment tools. Finally, GSR technologies available to remediate contaminated sites are described and the challenges and opportunities to the implementation of GSR technologies are discussed. GSR Definition and Objectives GSR is an holistic approach to protect human health and the environment while minimizing environmental side effects such as (1) minimize total energy use and promote the use of renewable energy for operations and transportation; (2) preserve natural resources; (3) minimize the waste generation and maximize the recycling of materials, and (4) maximize future reuse options for remediated land. In general, sustainability is defined broadly as meeting the needs of the present without compromising the ability of future generations to meet their needs. Sustainable remediation is a holistic approach to the remediation based on a broad array of environmental factors and community impacts applied during all phases of remediation in order to maximize the environmental, social and economic benefits (often known as the triple bottom line) associated with a project. Sustainable remediation is also broadly defined as a remedy or combination of remedies whose net benefit on human health and the environment is maximized through the judicious use of limited resources. Green remediation is the practice of considering all environmental effects of a cleanup during each phase of the process, and incorporating strategies to maximize net environmental benefit of the cleanup. Thus, green remediation can be recognized as part of the broader context of incorporating sustainability into remediation. GSR emphasizes the general preference of using green options to achieve sustainability in remediation. The main goal of GSR is to enhance a community’s long-term quality of life while preserving or improving the current standard of living for future generations (sustainability). The advantages of GSR include: (1) reduced impacts to the local environment, including air, water and soil; (2) increased energy efficiency, resulting in lower carbon emissions; (3) acceleration of ecosystem and biodiversity restoration; (4) reduced long-term maintenance costs; and (5) reduced energy costs. Overall, the objectives of GSR are: (1) achieve remedial action goals (risk-based levels), (2) reduce pollutant and waste burdens, (3) reduce air emissions and greenhouse gas production, (4)

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conserve natural resources, (5) minimize degradation or enhance ecology, (6) support use and reuse of remediated land, (7) increase operational efficiencies, (8) minimize impacts to water quality and water cycles, (9) achieve greater long-term financial return from investments, and (10) increase sustainability of site cleanups. It is important to recognize that the primary goal of any remedial approach (including the GSR) is to achieve remediation goals that are protective of public health and the environment. While trying to accomplish this, the following core elements that should be optimized to achieve GSR: (1) energy requirements, (2) water requirements and impacts to water resources, (3)air emissions, (4) land & ecosystem impacts, (5) material consumption and waste generation, and (6) long-term stewardship actions. These core elements of GSR are addressed through best management practices (BMPs) to achieve sustainable long-term net environmental benefit during all phases of site remediation (site investigation, remediation system selection and design, remediation system construction, operation and monitoring, and land end use) Energy requirements may be optimized by using passive remediation technologies that require little or no energy input, utilizing energy efficient equipment and/or renewable energy sources (e.g., solar, wind, etc.), and minimizing the long distance transport of materials and remediation personnel. Water requirements may be minimized by using technologies that limit the use of fresh water, incorporate systems that recycle water, maximize the use of reclaimed water and/or stormwater, use native vegetation requiring little or no irrigation, and prevent negative water quality impacts to nearby water sources. Air emissions, including pollutants and GHGs, may be minimized: using remediation technologies that minimize or prevent contaminant mass transfer into the gas/vapor phase, use cleaner-burning fuels for equipment, incorporate techniques that reduce operation and idle time, minimize dust-borne contaminants, incorporate alternatives to off-site transport and disposal of contaminated soils and wastes, and promote the sequestration of carbon dioxide in on-site soils. Land and ecosystem impacts may be minimized through the use of in-situ remediation technologies that minimize soil and habitat disturbance and incorporate eco-restoration practices. Material consumption and waste generation may be minimized by: using site investigation and remediation technologies that produce minimal waste, reduce the use and disposal of natural resources, and increase reuse and recycling of materials generated at or removed from the site. Beneficial long-term stewardship actions include the selection of adaptive and optimal remedial alternatives that: ensure long-term safety of public health, reduce the emission of GHGs that contribute to climate change, increase long-term carbon sequestration in soil and vegetative cover, and incorporate response action infrastructure into future site use. Various GSR Initiatives and Activities Government, industry, and professional organizations both in the United States and worldwide have been engaged in addressing various aspects of GSR with the ultimate goal of promoting GSR. Federal Agencies Presidential Executive Orders such as 13123: Greening the Government through Efficient Energy Management (1999), which have been the impetus for several U.S. federal agencies to

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pursue initiatives and activities that incorporate sustainability principles into remediation actions undertaken by various federal agencies. The executive order emphasizes the reduction in energy consumption and release of GHGs, among others. The United States Environmental Protection Agency (USEPA) has developed the Smart Energy Resources Guide to promote renewable energy technologies that reduce GHGs. The USEPA also developed a dedicated website (www.clu-in.org/greenremediation) that features profiles of projects and renewable energy fact sheets. The Superfund Green Remediation Workgroup of the USEPA has developed the Superfund Green Remediation Strategy that identifies twelve key action item areas to promote green remediation. The United States Army Corps of Engineers (USACE) has embarked on developing a decision framework to incorporate sustainable practices through all phases of remediation, including planning, investigation, remedial method selection, remediation system design, construction, operation, and maintenance, and site closeout. Existing platforms or protocols for each phase are being examined and modified to incorporate sustainable practices. For example, the USEPA Triad approach is considered, which decreases uncertainties through better site characterization, including the use of real-time field investigation tools that are less energy intensive and generate less waste. The United States Air Force (USAF) has been implicitly incorporating “sustainable” technologies in many of their remediation projects to reduce remediation system costs. Some of the preferred technologies considered sustainable and generally “green” include phytoremediation, LNAPL recovery, passive in-situ treatment, incorporation of wetlands, enhanced bioremediation, monitored natural attenuation (MNA), biowalls, solar-powered systems, and PBDS. Recently, the USAF began analyzing sustainability as a part of remediation system selection as well as optimization of ongoing remediation projects. In general, biological remediation systems operated by renewable energy sources (solar, wind) are being emphasized. Developed Sustainability Remediation Tool (SRT) and other remedial optimization tools. The United States Navy is considering sustainability during remedial selection and optimization of existing remedies based on a life cycle approach. This process has included consideration of key parameters, such as greenhouse gas emissions, energy use, water consumption, air emissions, community impacts, and safety. Metrics that may be used to define success have yet to be determined. In addition, different sustainability tools are being applied and evaluated. One of the Navy’s projects involved an evaluation of remedial alternatives to address BTEX impact in groundwater, including: (1) air sparging/soil vapor extraction (AS/SVE) and biosparging, (2) soil excavation and biosparging, and (3) soil excavation and MNA. In addition to an assessment of overall effectiveness, implementability, and cost, the evaluation included green and sustainability considerations. A qualitative evaluation was completed for hydrogeological impact, land use, collateral risk, and disturbances. GHG emissions and energy use were quantified over the project life cycle. It was determined that AS/SVE requires high energy input and results in a large GHG footprint, but operational modifications can reduce this impact. A comparison of energy and GHG for the three remedial alternatives was made.

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State Agencies Various state agencies in the United States are involved in promoting and developing guidance on implementing sustainable remediation practices in remedial actions in their states. Wisconsin’s Initiative for Sustainable Cleanups (WISC) is developing a guidance document to present sustainability performance metrics and implement sustainable remediation into State and federal remedial actions. The document will also provide a process for green optimization of existing remediation systems. Elements of green remediation considered include energy/carbon, land use/ecosystem, materials/waste, facilities, air, water, and soil. Sustainability metrics include carbon dioxide equivalents (CO2e), energy use (kWh, gals, therms), water use (gallons), waste generated (tons), and cost ($/kWh, $/ton CO2e, etc.). Green management practices/considerations include: waste reduction and recycling, sustainable end land use, storm water management, air emissions reduction, carbon management, energy efficiency, and Leadership in Energy and Environmental Design (LEED) criteria. Based on this guidance, sustainable options for six selected state funded remediation sites will be recommended. WISC is exploring options for standardized sustainability metrics under three categories: economic, environmental and social/community. Economic metrics considered include life cycle remediation costs, including capital and operation and maintenance, dollars per unit contaminant removed, cost per sustainability metrics ($/kWh, $/ton CO2eqv), and green building/leadership in energy and environmental design (LEED). Environmental metrics include energy use (kWh), GHGs (CO2eqv), water use (gal), waste generation (t), recycling (t), and renewable energy (kWh). Social/community metrics considered include safety (total reportable incidents), traffic (vehicles per day), fugitive dust, vapors, noise and odor, beneficial land use, landscape planning (including carbon sink analysis), community involvement (e.g., public meetings, written communication), and transparent reporting. Minnesota Pollution Control Agency is developing internet-based toolkit that will help incorporate sustainability concepts in planning remediation while addressing regulatory requirements. California Department of Toxic Substances Control (CA-DTS developed the Green Remediation Initiative to promote the use of green technologies that are least disruptive to the environment, generate less waste, enhance recyclability, and emit fewer pollutants and greenhouse gases to the atmosphere. Specific attention is focused on the active and closed military sites under this initiative. Illinois Environmental Protection Agency (IEPA) has developed a matrix of sustainable practices that can be applied to site assessment, planning and design, and remediation. The matrix lists individual actions, followed by a qualitative ranking of their level of difficulty and feasibility (subcategorized by cost, schedule, and technical complexity). The benefits of each action to air, water, land, and energy are also identified. Other Organizations The Sustainable Remediation Forum (SuRF) consists of member organizations mostly located in the United States. The mission of SuRF is to establish a framework that incorporates sustainable

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concepts throughout the remedial action process while continuing to provide long-term protection of human health and the environment and achieving public and regulatory acceptance. Sustainable remediation is defined as a remedial method or combination of methods whose net benefit on human health and the environment is maximized through judicious use of limited resources. SuRF published a white paper on Integrating Sustainability Principles, Practices and Metrics into Remediation Projects. The white paper evaluates the current status of sustainable remediation practices, identifies the various perspectives advocating for or against sustainable remediation, and considers how sustainable practices improve the status quo. SuRF defines sustainable practices that reduce global impacts (GHGs) as well as reduce local atmospheric effects, potential impacts on worker and community safety, and/or the consumption of natural energy resources (beyond fuel consumption) that might be attributed to remediation activities. An opinion survey of SuRF members and regulators in the United States and Canada was conducted, identifying support for sustainable remediation. However, the survey feedback indicated a lack of guidance, policy, or programs specifically addressing sustainable practices in remediation. Some of the noted challenges of including sustainability in remediation projects included regulatory complications and/or resistance, impediments to overall work progress, the tendency for sustainability metrics to override other factors, valuation of resources, and stakeholder education. The Association of State and Territorial Solid Waste Management Officials (ASTSWMO) formed the Greener Cleanups Task Force to facilitate remediation decisions that increase the net environmental benefits of remediation and contribute to site sustainability. The goals of the task force include: identification of best practices and incentives for greener cleanups, support for state programs to integrate green approaches into the remediation system selection process, strengthening partnerships between States and USEPA to improve greener remediation capacities, and operation as a technical resource for ASTSWMO task forces. The task force is working on strategy papers dealing with policies, incentives, barriers, toolkit, etc. It has also conducted a survey of states to identify barriers and incentives to implementing greener remediation. The major barriers identified from this survey included a lack of knowledge/awareness of greener remediation practices, higher upfront costs, a lack of requisite implementation guidelines or regulations, and a lack of incentives. Major existing incentives include loans and grants, publicity/recognition, and contract incentives. Interstate Technology and Regulatory Commission (ITRC) formed Green and Sustainable Remediation Team, with about 100 members from state and federal agencies, consulting and industry representatives and few academics, identified an absence of a nationwide guidance on how to best incorporate GSR into a regulated remediation process as well as a consistent approach on how to use and interpret sustainability metrics and/or life cycle analysis. Additionally, ITRC indicated a need to communicate best practices to state regulators and environmental consultants. Therefore, it is working towards developing documents and training to educate state regulators and other environmental professionals on how to appropriately incorporate sustainability and green technologies into the remediation process. American Society of Testing and Materials (ASTM) has a Subcommittee on Corrective Action (E50.04) is developing a standard guide for green remediation that evaluates and recognizes efforts to maximize the net environmental benefit of cleaning up contaminated sites. The goal of

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the standard is to establish a uniform approach that will encourage property owners, responsible parties, developers, and communities to use green remediation practices during planning and implementation. International Activities In Canada, the Ministry of Environment of the Province of Quebec introduced a sustainability development concept through principles of prevention, rehabilitation/reclamation, polluter financial liability, and fairness. These principles address several socio-economical aspects, but the environmental externalities such as GHGs and impacts on the local communities are not considered. Contaminated Land: Applications in Real Environments (CL:AIRE) in the United Kingdom (UK) is a not-for-profit organization established for the regeneration of contaminated land in the UK. It is currently leading the Sustainable Remediation Forum-UK (SuRF-UK) to develop a framework for balanced decision making in the selection of remediation strategies that address land contamination as an integral part of sustainable development. Soil and Groundwater Technology Association (SAGTA) in the UK is a nonprofit association of member organizations drawn from UK industry. It aims to address the technical challenges associated with contaminated land management. Network for Industrially Contaminated Land in Europe (NICOLE) and SAGTA are collaborating to define and implement sustainable remediation. NICOLE is a leading forum on contaminated land management in Europe that promotes cooperation between industry, academia and service providers on the development and application of sustainable technologies Decision Framework A sustainable remediation framework represents the confluence of environmental, social and economic factors for decision-making. The framework is useful for comparing remedial alternatives and improving ongoing remediation projects. The framework concept refers to a range of practices and objectives that can be integrated into a project to increase sustainable practices and objectives. Unfortunately, a standardized decision framework has not been developed as of today, but there has been considerable discussion on desirable practices and objectives. For example, the USEPA’s Green Remediation Primer lists several environmental, social and economic practices and objectives that should be considered for the framework. To be useful and meaningful, a decision framework should address at least incorporate the following major parameters:

• Reduced energy consumption associated with site remediation, the manufacture of consumables, and the management of residual soil and groundwater impacts. Additionally, renewable energy sources should be incorporated when possible.

• Minimize GHG emissions should be undertaken through the use of BMPs, including in-situ GHG sequestration within soils and/or vegetation.

• The use of remedial technologies that do not require on-site or off-site waste disposal.

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• The use of remedial technologies that utilize recycled and/or reclaimed water sources, thereby reducing the need for fresh water. Additionally, technologies that promote the reuse and recycling of by-product materials should be incorporated.

• When appropriate, the use of remedial technologies or strategies that that do not restrict the potential future land use of a site. Strategies should be used that will encourage land revitalization for beneficial reuse and/or improved ecology. However, the costs and benefits of the resources consumed during remedial activity should be compared to the economic, social, and public health benefits gained from partial remediation that incorporate engineering or land use controls.

A framework based on these factors is a critical component to facilitate the selection, design, and implementation of sustainable remedies at contaminated sites. By incorporating site-specific information, particularly the type and extent of contamination identified during site investigations, various potential remedial alternatives may be identified. Each alternative implementation is then assessed in detail for sustainability factors, such as greenhouse gas emissions, energy and materials consumption, land use, and water use. In order to assess these factors, relevant and beneficial sustainability metrics and assessment tools are required, which become critical components of decision framework. Sustainability Metrics In general, the metrics used for sustainable remedial performance have not been standardized. Traditional remediation metrics include remediated area (m2), mass of treated contaminants (t), and mass of treated soil (t). Complementing these metrics, performance may also be measured by:

• Energy consumption, expressed in kWh or BTU • Water consumption expressed in gallons or m3 • Waste generation expressed in tons • Greenhouse gas emissions in terms of carbon dioxide equivalents or tons • Air pollutants in terms of tons

In addition, positive actions, such as renewable energy use, materials recycling (or natural resources preservation), site redevelopment and re-use, ecological restoration, etc., may also be considered. Environmental intensity indicators may better serve as metrics for evaluations; some examples include:

• Energy per unit treated mass (kWh/kg), • Water used per unit treated soil mass (m3/kg), and • Carbon dioxide emissions per unit treated soil mass (t/kg).

The associated environmental costs are indicated by cost per unit remediated area ($/m2), cost per unit treated contaminant mass ($/kg), and cost per unit treated soil mass ($/kg). Unfortunately, there are no standards for sustainable metrics. To properly assess the efficacy of sustainability factors, it will be essential to establish a standard sustainable remediation unit that encompasses all sustainability parameters.

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Assessment Tools Tools are needed to calculate sustainability metrics, which are being developed. Qualitative and quantitative assessment tools are being developed to calculate sustainability metrics to help consider all factors in designing and implementing remediation systems. These tools can range from simple decision trees and Excel Spreadsheets to complex full life-cycle assessments. Qualitative assessment tools facilitate the screening of different remediation technologies based on potential impacts on the environment, society, and economics. These tools, which allow preliminary determination of potential remedial technologies, include:

• California DTSC developed a matrix that ranks the material and energy inputs and outputs associated with all elements of a remedial method;

• Illinois EPA developed a two-page matrix that identifies the environmental benefits of each activity in remediation in terms of air, water, land, and energy;

• Minnesota Pollution Control Agency created an Internet-based interactive toolkit that includes a decision tree and checklist of factors to consider in remedial method selection.

Efforts have recently been undertaken by industry and government agencies to develop tools that specifically quantify the impacts of remediation technologies on the environment, society, and economics. Unfortunately, many of these tools are not available to professionals, and the basis for the calculation of sustainability metrics is not well documented. GSI Environmental Inc. developed the Sustainable Remediation Tool (SRT) for the Air Force Center for Engineering and the Environment (AFCEE) to assist environmental professionals in incorporating sustainability concepts in their remedial method decisions. SRT, based on a Microsoft Excel platform, estimates sustainability metrics for four specific technologies (excavation and soil vapor extraction for soil remediation, and pump and treat and enhanced bioremediation for groundwater remediation). Additional modules are being developed to assess other technologies. Currently, sustainability metrics included in SRT include carbon dioxide emissions to atmosphere, total energy consumed, change in resource service, technology cost, and safety/accident risk. Additional sustainability metrics are reportedly being added to SRT. SRT can be implemented as Tier 1 or Tier 2 analysis. Tier 1 is based on generalized input and is considered most appropriate for a preliminary feasibility study. Tier 2 is based on user-defined, detailed, site-specific criteria; it is considered appropriate after a feasibility study or for optimization of existing systems. USEPA and its partners have developed several tools to help individuals and organizations determine the greenhouse (GHG) impact of their purchasing, manufacturing, and waste management actions. Several of these tools are based on EPA research on emission factors, as reported in Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks and associated reports. These models can be found at www.epa.gov/climatechange/wycd/waste/tools.html. One example, WAste Reduction Model (WARM) calculates and totals GHG emissions of baseline and alternative waste management practices—source reduction, recycling, combustion, composting, and landfilling. The model calculates emissions in metric tons of carbon equivalent (MTCE), metric tons of carbon dioxide equivalent (MTCO2E), and energy units (million BTU) across a wide range of material types commonly found in municipal solid waste (MSW). EPA’s Pollution Prevention Program (P2)

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developed a GHG Calculator tool to help quantify GHG reductions from established conversion factors in the following categories:

• Electricity Conservation (GHG reductions from electricity conversation or reduced use of energy)

• Green Energy (GHG reductions from switching to greener or renewable energy sources) • Fuel Substitution (GHG reductions from reduced fuel use, substitution to greener fuels) • Greening Chemistry (GHG reductions from reduced use of GWP chemicals) • Water Conservation (GHG reductions from reduced water use) • Materials Management (GHG reductions from green manufacturing processes and waste

management scenarios) • Cross Reference to other applicable tools (A reference table that provides end users an

overview of applicable GHG tools and models) Because there is no universally accepted way of calculating a carbon footprint, dozens of carbon calculators have become prevalent over the past few years, creating confusion and inaccurate information. Adding to that confusion are the accepted frameworks for tracking industry carbon emissions that rely on “tiers” of increasingly broad scope. The tier-one boundary, for example, generally includes emissions by a company’s own activities, such as fuel consumption in fleet vehicles or facilities. The second-tier boundary expands to include emissions from electricity and steam purchased by the company. Tier-three includes all other emissions, including the entire supply chain of goods and services. Most companies that report their greenhouse gas emissions use only their tier-one or tier-two boundary, thus overlooking total greenhouse gas emissions. It is recommended to use a life cycle assessment (e.g., EIO-LCA) to properly analyze carbon footprint and other impacts. The International Organization for Standardization (ISO) 14040 series presents a standardized method of life cycle assessment (LCA) to determine the environmental and human health impacts of products or services. In ISO 14040, LCA is defined as the compilation and evaluation of the inputs, outputs, and potential environmental impacts of a system throughout its life cycle. LCA has been used commonly to evaluate the total effects that a product has on the environment over its entire existence; starting with its production and continuing through its eventual disposal. It accounts the energy and resource inputs, as well as the polluting outputs to land, water and air that result from the production of a product. In general, framework for LCA involves:

• goal definition and scope • inventory analysis (includes constructing the process flow chart, collecting the data,

defining the system boundaries, and processing the data) • impact assessment (includes classification and characterization, valuation) • improvement assessment (reporting and improvement assessment)

Prior to performing LCA, one must be clear with the specific objectives of the analysis, data requirements, and critical assumptions to be made. A process flow chart will help identify the scope of analysis, nature and amount of data required, and logical system boundaries. In principle, the analysis boundaries should include all resource extractions and environmental emissions related to a product or process. Materials and energy sources should all be taken into account. A limited number of available databases may be useful to obtain some of the data.

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Impact assessments can include human toxicity, ecotoxicity, global warming, energy depletion, etc. For each impact, inputs and outputs should be assigned. Some of the impacts may be aggregated for simplicity. Interpretation of the results may be based on defining a single environmental index that encompasses all of the impacts. LCA can provide a quantitative approach that provides an objective, scientific, and numerical basis for decision-making of remediation technologies. LCA can be used:

• Provide benchmarking for existing systems • Retrospectively identify opportunities to decrease impacts in future remediation • Retrospectively identify where specific improvements would be most advantageous, • Compare different remediation options during the technology selection process.

LCA is based on a holistic approach that accounts for both direct and indirect impacts during all phases of remediation, including the site characterization, remediation system implementation, operation and monitoring, and a site’s anticipated end use. LCA is a decision-making tool to select the best GSR approach based on the evaluation of different remedial alternatives that not only protect public health and safety but also minimize the consumption and maximize reuse of natural resources (e.g., minerals, water, land, fossil fuels), maximize the use of renewable energy sources, minimize the generation of solid and liquid wastes, air pollutants and GHGs, utilize the site for useful end use, and restore local habitat and ecosystem. Based on the associated costs and benefits as well as efficiency and effectiveness considerations, LCA will help selection of the best GSR strategy to be implemented at a given site. LCA is a complex environmental assessment tool that requires significant data that are often hard to find or expensive to purchase. The selection of boundaries for LCA is also a difficult task. However, LCA is flexible, allowing for simplification based on the specific application, simplified assumptions, and defined assessment boundaries. Thus, LCA can be made as an elaborate research tool or a “quick-and-simple” assessment tool. Even in the case of simple LCA application for GSR, one must require the following input data:

• Personnel (e.g., labor, design professionals) • Consumable supplies (e.g., process feedstock, reagents or chemical compounds) • Natural resources (e.g., water, minerals, land) • Renewable and nonrenewable sources of energy, including all energy requirements for

the implementation and operation of a remediation system as well as the energy required for associated operations, such as transport of personnel, materials, remediation by-products, etc.

LCA also requires the following output data: • Generation of solid and liquid wastes • Emission of air pollutants and GHGs • Useable by-products • Nuisances and disturbances (e.g., noise, odor) on ecosystem and biosphere

It should be recognized that the collection of the above input and output data is often a time-consuming and difficult task. Applications of LCA for the remedial strategy optimization at contaminated sites are relatively scarce. This is mainly attributed due to lack of training on LCA for environmental remediation

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professionals, complexities involved in LCA, lack of input and output data required for LCA, and significant time requirement. Moreover, LCA requires interdisciplinary collaboration. Because of the requirement for simultaneous fulfillment of multi-faceted aspects of GSR, LCA can serve as the most logical decision-making tool for comparative evaluation of alternative remedial options with the baseline (traditional) remedial option. The Economic Input-Output Life Cycle Assessment (EIO-LCA) method estimates the materials and energy resources required for, and the environmental emissions resulting from, activities in our economy. Researchers at the Green Design Institute of Carnegie Mellon University transformed EIO-LCA method into a user-friendly, on-line tool to quickly and easily evaluate a commodity or service, as well as its supply chain (CMU-GDI, 2009). EIO-LCA provides guidance on the relative impacts of different types of products, materials, services, or industries with respect to resource use and emissions throughout the supply chain. This method has been used extensively for product development, but its application to assess sustainability parameters of site remediation has received attention only recently. GSR Technologies The key principles and factors of GSR should be incorporated during all phases of a remediation program, including (1) site investigation, (2) remediation system selection, (3) design, construction, and operation, (4) monitoring, and (5) site closure and determination of appropriate future land use. When analyzing an impacted site, these principles should be integrated into a cohesive remedial and end use strategy. However, appropriate consideration of these factors is highly dependent on accurate site characterization; technical professionals need to pursue a systemic approach to properly characterize site-specific parameters. The use of the USEPA’s Triad decision-making approach is highly recommended for site investigations. This method consists of three interrelated components; (1) systematic project planning, (2) dynamic work strategies, and (3) real-time measurement technologies to reduce decision uncertainty and increase project efficiency. Appropriate sustainability principles can be incorporated into site characterization activities. For example, direct push technologies, geophysical techniques, and passive sampling and monitoring techniques can reduce waste generation, consume less energy, and minimize land and ecosystem disturbance. It can be challenging to incorporate sustainability parameters into the process of selecting remedial technologies. A wide range of ex-situ and in-situ remediation technologies have been developed and implemented at contaminated sites. Although many remediation technologies have been developed to meet the cleanup goals, potentially damaging environmental side effects, such as air pollution, water use and impacts, energy consumption, land and ecosystem impacts, natural resource consumption, and waste generation have not received greater attention. Some technologies, such as pump-and-treat operations and incineration are known to be energy-intensive, yet they may not provide net environmental benefit if there are analyzed from a holistic standpoint. Recall the goal of GSR aims is to meet remediation objectives while minimizing environmental side effects so that net environmental benefit can be realized. An ideal remediation technology (and all associated on-site or off-site actions) should aim to:

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• Minimize the risk to public health and the environment in a cost-effective manner and a reasonable time period.

• Eliminate the potential for secondary waste and prevent uncontrolled contaminant mass transfer from one phase to another.

• Provide an effective, long-term solution. • Minimize the impacts to land and ecosystem. • Facilitate appropriate and beneficial land use. • Minimize or eliminate energy input. If required, renewable energy sources (e.g., solar,

wind, etc.) should be used. • Minimize the emissions of air pollutants and GHGs. • Eliminate fresh water usage. All appropriate actions and technologies that recycle and

reuse water should be incorporated. Additionally, reclaimed water and stormwater sources should be used in place of fresh water. Further, the remedial action should minimize impact to natural hydraulics and nearby water sources.

• Require minimal material use while facilitating recycling and/or the use of recycled materials.

Remediation technologies may be based on physico-chemical, thermal, biological and electrical principles that aim to remove, immobilize, or destroy the contaminants. These technologies may be implemented in-situ or ex-situ. Technologies that encourage uncontrolled contaminant partitioning from one media to another (i.e., from soil to liquid or from liquid to air) or those generate significant secondary wastes/effluents are not sustainable. Rather, technologies that destroy the contaminants (such as bioremediation, chemical oxidation/reduction), minimize energy input, and minimize air emissions and wastes, are preferred. In-situ systems are often attractive, as they typically minimize greenhouse gas emissions and limit disturbance to ground surface and the overlying soil column. Conversely, ex-situ systems typically provide a greater ability for soil mixing and tilling, allowing for better control of electron donor substrate/nutrient applications. As a result, remediation times are often shorter when ex-situ systems are used. Additionally, amendments used in ex-situ applications may often lead to a greater degree of remediation, resulting in a greater range of beneficial reuses for a particular site. A variety of remedial technologies satisfy core GSR criteria; however, the project life cycle for a specific technology should be consider to determine if it is appropriate for use at a given site. For example, ex-situ biological soil treatment is considered a promising GSR technology; however, the impacts of transporting soil (if off site treatment is required) should be evaluated. Similarly, enhanced in-situ bioremediation is also considered an attractive GSR technology, but the cumulative impacts that occur during its characteristically long treatment duration should be compared to those of a more aggressive active remediation that occurs over a shorter period of time. In general, passive containment systems such as phytoremediation and permeable reactive barriers utilize little mechanical equipment (and therefore, minimal energy input). Additionally, these systems result in minimal waste/effluent to manage. While active containment systems have ability to prevent contaminant migration, a potential exists where water quality within receiving water can be degraded. Finally, in-place management using MNA with engineering

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controls is often compared with a more aggressive excavation and disposal scenario. In-place management eliminates the potential for GHG or other emissions; however, excavation and disposal allows for rapid remediation and often eliminates the need for engineering or institutional controls. A single remediation technology often cannot cost-effectively address the technical challenges posed by contamination at a particular site. Based on the site-specific conditions, multiple technologies may be used sequentially or concurrently to remediate contamination. For example, aggressive active technologies may be needed to remediate source zones to prevent source migration and/or reduce the remediation time duration. When considered alone, these technologies may not be considered sustainable; however, by reducing the potential for migration and/or remediation duration, the use of these technologies can often greatly enhance the sustainability aspects of a given program. Additionally, some popular technologies used to treat lower concentrations and/or residual contamination is not considered effective in treating source remediation. Groundwater plumes with moderate to high dissolved contaminant concentrations may also require implementation of active remediation technologies for a relatively short duration to expedite contaminant mass reduction. Alternatively, it is known that technologies appropriate for source removal are often ineffective in treating residual or lower concentration conditions. From a physical standpoint, slow diffusion and dissolution of contaminants at later stages of remediation lead to a tailing effect. Under such conditions, greenhouse gas emissions and energy usage may outweigh the amount of the extent of contaminant mass removal/destruction. Therefore, under such conditions, a technology with lower energy requirements should be implemented to treat residual contamination while minimizing energy usage and greenhouse gas emissions. Large dilute groundwater plumes may be treated from the beginning using lower-energy passive technologies; this may extend the duration of the remediation program, but it will reduce overall net impacts to the environment. The duration of the remediation program can itself be a major governing factor in remediation system selection. Remediation technologies such as bioremediation may require lower energy input, but they require longer treatment time. Further, given the duration of the remediation, cumulative energy use can often be greater as compared to a shorter but energy-intensive remediation program. Other anticipated or unanticipated side effects, such as those associated with incomplete mineralization, can render these as ineffective alternatives. Further, even energy-intensive aggressive technologies, such as thermally enhanced remediation, may become a very attractive option from a sustainability standpoint if this energy is generated from renewable sources. USEPA has performed an analysis of the estimated energy use and associated carbon footprint for selected remediation technologies. When considering these parameters, low energy remediation systems are often preferred. USEPA (2008) identified enhanced bioremediation, phytoremediation, soil amendments, evapotranspiration covers, engineered wetlands, biowalls, and MNA as low energy remediation technologies. Renewable energy sources (solar, wind,

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geothermal, biogas (landfill gas), biomass, and low-impact small hydroelectric sources) should be incorporated into GSR to reduce the GHGs and carbon footprint as well as reduce the remedial costs. They can be used to meet partial or full demand of remedial actions. Often, initial capital costs will be high, but remediation programs that require longer treatment time will recover these costs through reduced energy costs. Additional tax credits and incentives may also lead to significant cost savings. Additionally, opportunities exist for reducing energy and carbon footprints from existing remediation systems. In particular, energy efficiency can be maximized in site remediation projects by optimizing existing treatment systems, design evaluation and upgraded equipment. In addition, alternative sources of energy, including solar, wind, landfill gas, biomass, geothermal, tidal/wave, and cogeneration can be incorporated into existing systems and should be explored. A growing number of existing projects have incorporated renewable energy sources, as documented in case studies compiled by the USEPA. It is difficult to compare or quantify the relative sustainability of different remediation technologies. It is suggested that “unit of remediation” be defined which can be used for such evaluations, including in life cycle assessments. Assessments should also consider balancing time of remediation and cost in remedy selections. In some cases, active remedies may prove effective. Triple bottom line (environmental, social and economical) impacts should be evaluated to achieve a truly sustainable remedial solution. Case Studies Traditional remediation does not address sustainability parameters such as greenhouse gas emissions, natural resource consumption, energy use, worker safety, and/or local and regional impacts. Recently, industry stakeholders have begun to address these broader impacts at all stages of remediation, from investigation, remedy design and implementation and site end-use. By including these broader impacts, remediation has become more holistic approach to solve environmental problem. Industry stakeholder and government agencies have started to publicize such case studies. USEPA (2008) presents several case studies that use GSR for site remediation. These case studies document utilization of renewable energy sources, reduction in waste generation, recycling and reuse of materials, and beneficial land end use. SuRF White Paper also presents some case studies. A life-cycle framework specifically applicable to site remediation was developed by the Ontario Ministry of the Environment (Diamond et al., 1998). It essentially involved developing a process-flow diagram and identifying all of the process inputs and outputs. Individual inventory items are linked to a potential environmental impacts checklist. This checklist associates the impacts with the physical, chemical, or biological stressors. Each stressor can be ranked by level of concern if sufficient process information is known. At the simplest level, the framework approach helps identify key areas for improvement or opportunities for reducing burdens. Page et al. (1999) presented a comparative study to demonstrate the application of this framework.

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Volkwein (1999) discussed a tool using a streamlined LCA combined with the results of a risk assessment to assess the primary and secondary impacts of three remedial options (dig-and-haul, installation of an asphalt cap, and thermal/biotreatment) for a contaminated site in Germany. Godin et al. (2004) evaluated four remedial options (dig and haul, excavation and treatment, excavation and incineration in a cement kiln, and leaving the soil in place) to identify a remediation option that minimizes overall environmental impacts based on a comparative LCA and contaminant groundwater transport modeling. Toffoletto et al. (2005) described a retrospective LCA of ex-situ bioremediation to identify several process optimizations to reduce the environmental load of the treatment (Figure 1).

Figure 1. Life Cycle flow diagram (Toffoletto et al., 2005) Cadotte et al. (2007) applied LCA to evaluate in-situ and ex-situ methods to remediate a LNAPL site. Factors included treatment time, residual contamination impacts and remediation method impacts to determine the best combination of three soil and four groundwater technologies to use at the site. Lesage et al. (2007) used an LCA approach to evaluate impacts of a brownfield site remediation and the reuse of the property. Recently, Higgins and Olsen (2009) performed

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comparative LCA of PAT and PRB and showed that PRB is effective in providing net environmental benefit. Challenges and Opportunities One can’t compromise the most important criterion of site remediation: the selected remediation method should be protective of public health and the environment.

• Lack of education and training for stakeholders • Environmental professionals and stakeholders currently do not consider GSR

technologies in practice because they are not fully aware of their applicability and benefits, nor have they been exposed to design and selection criteria that are necessary for implementation.

• Lack of guidance documents with clear and consistent definitions. Guidance documents are being developed to educate practicing professionals on the benefits of green remediation and approaches of incorporating green concepts in all phases of remediation

• Lack of standardized sustainability metrics and validated evaluation tools. LCA can be be the best tool. Currently, there are no training programs available that specifically focus on teaching the application of LCA for GSR. Because of the wide range of relevant and complex parameters, LCA application for GSR requires collaboration of a wide range of stakeholders, including academic researchers, consulting firms, contractors, government agencies, product/technology vendors, and responsible parties.

• Lack of well defined framework and process to evaluate sustainability- The common perception of regulators, environmentalists and general public is that responsible parties may misuse GSR to justify the pursuit of a “no action alternative”, perceived “hands-off” remedies such as monitored natural attenuation, capping/containment, or cursory incorporation of selected sustainability principles (i.e., renewable energy sources) that provide little overall benefit.

• Lack of well documented pilot studies/case studies involving sustainable remedies- Reported case studies mainly high light the use of renewal energy sources

• Lack of incentives to adopt sustainable remedies- Contractual language is also being developed to encourage contractors to seek green strategies in design, construction and operation of remediation systems.

• Lack of funding to support the research and development of sustainable approaches • Currently, no specific regulations requiring GSR exist. However, GSR can be

incorporated under existing federal and state regulatory frameworks or criteria related to site remediation (e.g., CERCLA, RCRA, Brownfields). For example, Superfund (CERCLA) stipulates nine criteria that must be met when selecting a remedial method. Threshold criteria: overall protection of human health and the environment; and compliance with ARARs. Primary balancing criteria: long-term effectiveness and permanence; reduction of toxicity, mobility or volume; short-term effectiveness; implementability; and cost. Modifying criteria: state/support agency acceptance; and community acceptance.The core elements of GSR may be incorporated into any of these criteria. Some suggest that new sustainability-specific criteria into the current regulatory framework (RCRA, CERCLA) will promote sustainable practices and provide a consistent guidance/standard for GSR implementation.

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Summary Green and sustainable remediation (GSR) is a rapidly evolving approach for the remediation of impacted sites. The objectives of GSR aim to achieve remedial goals through more efficient, sustainable strategies that conserve resources and protect air, water, and soil quality through reduced emissions and other waste burdens. Many project stakeholders are aware that many traditional remediation technologies can often be labor-, energy- and carbon-intensive. Because of the impacts these technologies impart on the environment and society as a whole, the GSR approach provides an attractive alternative to mitigate these impacts while striving to maximize the environmental, social and economic benefits (often known as triple bottom line) associated with a project. Many environmental professionals and project stakeholders do not utilize GSR technologies because they are unaware of methods for selection and implementation. Additionally, the absence of guidance on standardized sustainability metrics and assessment tools for GSR implementation can limit its effectiveness and application. The development of a sustainable remediation framework will allow the selection and optimization of all phases of remedial action, leading to a net benefit to environment, society and economy. Industry and government stakeholders should continue to promote sustainability in site remediation. In addition, incentives should be provided to stakeholders for successful implementation of sustainable remediation technology. There is a paramount interest and urgency among environmental professionals to address the environmental, economic and social aspects of sustainability into the remediation system selection and implementation. Green and sustainable remediation offers a holistic approach to evaluate technical, societal and economic impacts of remediation, leading to the selection of remedy that provides maximum net environmental benefit. All of the stakeholders recognize this benefit and support this approach. However, there are many challenges that must be overcome in order to make GSR a standard practice. References Cadotte M., Deschenes L., and Samson R. (2007). Selection of a Remediation Scenerio for a

Diesel-Contaminated Site Using LCA. Int. Journal of Life Cycle Assessment, Vol. 12, 239-251.

CMU-GDI (Carnegie Mellon University Green Design Institute). (2009). Economic Input-Output Life Cycle Assessment (EIO-LCA), US 1997 Industry Benchmark model, http://www.eiolca.net.

Diamond M.L., Page C.A., Campbell M., McKenna S., and Lall R. (1999). Life-cycle Framework for Assessment of Site Remediation Options: Method and Generic Survey. Environmental Toxicology and Chemistry, Vol. 18, 788-800.

Ellis D.E. and Hadley P.W. (2009). Sustainable Remediation White Paper-Integrating Sustainable Principles, Practices, and Metrics Into Remediation Projects. Remediation, John Wiley.

Godin, J. Menard J.F., Hains S., Deschenes L., and Samson R. (2004). Combined Use of Life Cycle Assessment and Groundwater Transport Modeling to Support Contaminated Site Management. Human and Ecological Risk Assessment, Vol.10, 1099-1116.

Higgins M.R. and Olsen T.M. (2009). Life-Cycle Case Study Comparison of Permeable Reactive Barrier versus Pump-and-Treat Remediation. Environmental Science and Technology, Vol.43, No.24, 9432-9438.

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Lesage P., Ekvall T., Deschenes L. and Samson (2007). Environmental Assessment of Brownfield Rehabilitation Using Two Different Life Cycle Inventory Models. Int. Journal of Life Cycle Assessment, Vol. 12, 391-398.

Page C.A., Diamond M.L., Campbell M., and McKenna S. (1999). Life-cycle Framework for Assessment of Site Remediation Options: Case Study. Environmental Toxicology and Chemistry, Vol. 18, 801-810.

Sharma H.D. and Reddy K.R. (2004). Geoenvironmental Engineering: Site Remediation, Waste Containment, and Emerging Waste Management Technologies. John Wiley, Hoboken, NJ.

Toffoletto L., Deschenes L., and Samson R. (2005). LCA of Ex-situ Bioremediation of Diesel-Contaminated Soil. Int. Journal of Life Cycle Assessment, Vol. 10, 406-416.

USEPA (2001), Using the Triad Approach to Improve the Cost-effectiveness of Hazardous Waste Site Cleanups. EPA 542-R-01-016, Washington, D.C.

USEPA (2008). Green Remediation: Incorporating Sustainable Environmental Practices into Remediation of Contaminated Sites. EPA 542-R-08-002, Washington, D.C.

Volkwein S., Hurtig H.W. and Klopffer W. (1999). Life Cycle Assessment of Contaminated Sites Remediation. Int. Journal of Life Cycle Assessment, Vol. 4, 263-274.

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