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Green and Sustainable Remediation
Throughout industry and the general public, there is increasing focus and awareness to "go green." This concept is also being adopted for environmental investigations and remediation projects and has resulted in a new approach to environmental restoration termed by some as green and sustainable remediation.
This site is intended to assist managers with the selection of appropriate remedies for their sites that incorporate green remediation strategies.
What is Green and Sustainable Remediation?
Yesterday's remediation approaches often impact the very environment that is undergoing restoration. For example, remediation equipment typically operate on diesel, resulting in increased green house gas emissions. (GHGs) Today one must consider the short- and long-term environmental effects associated with remedial activities.
Green and sustainable remediation considers the environmental impact of an investigation and remedy activities during the remedy selection process. Incorporating green and sustainable remediation into an environmental restoration project requires evaluating activities and selecting a remedy that minimizes the environmental impact from the remedy, yet provides the maximum environmental benefit to the cleanup over the entire life of the remedial project.
The following are just some of the green and sustainability issues to be considered when selecting the remedy:
- What are the energy requirements to operate the system throughout the entire life of the remedy?
- Are natural resources going to utilized and/or impacted when implementing the remedy (e.g., water, soil)?
- Are pollutants going to be utilized or created as a result of the remedy?
- How effective will the remedy be versus the impact of the remedy on the environment as a whole?
- What are the impacts of operating the remedy (e.g., GHG emissions, disturbance of native flora, etc.)
Why is Green and Sustainable Remediation important?
The use of green and sustainable remediation by the Air Force in environmental restoration programs is becoming an increasingly important priority. This is due to heightened public awareness on the issue, increased regulatory requirements, and federal mandates (EO 13423) to improve the sustainability of federal government operations by achieving improvements in the specific areas, including the following:
- GHG emissions
- Toxic chemical usage and disposal
- Energy consumption
- Use of alternative fuels
- Water consumption
- Waste generation
Current Regulatory Green Remediation Initiatives
US EPA Initiatives
The US EPA has issued several guidance documents that provide recommendations for green remediation. These documents have primarily focused on reducing the fossil fuel energy consumption associated with remediation. However more recent publications include specific Green Remediation Primer, which provides some very good general information on the subject as well as some examples, including some on DoD installations. The US EPA has also compiled a web site which serves as a launching site to many more resources on green and sustainable information. In addition, the EPA is working with multiple partners to develop green cleanup standards and a verification system that evaluates and recognizes the full impact of a of a cleanup to maximize the net environmental benefit of engineered remedies. For more information contact Deb Goldblum, Region 3 RCRA CA, goldblum.deborah@epa.gov, 215-814-3432.
State Initiatives
Several states are developing guidance for "greener cleanups." The State of California is preparing guidance on how to integrate green technologies into the remedy selection process and how to evaluate the environmental impacts of a proposed remedy. The State of Illinois recently released a reference document in the form of a matrix entitled Greener Cleanups: How to Maximize the Environmental Benefits of Site Remediation. The Interstate Technology & Regulatory Council (ITRC) has established two teams on the topic, the Risk Remediation Management (RRM) Team and the Green Sustainable Remediation (GSR) Team. The RRM team is striving to advance innovative approaches to remediation decision making by educating regulators on the many uncertainties/risks associated with remediation and closure of contaminated sites. The GSR team is striving to facilitate discussion in the regulatory community advantages and disadvantages of sustainable and green remediation during remedy selection, implementation and post implementation phases. Both teams will be producing technical and regulatory documents as well as free online technical training to help state environmental agencies gain valuable technical knowledge and develop consistent regulatory approaches for reviewing and approving specific technologies.
Global Initiatives
The focus on green and sustainable remediation is not limited to the US. The European Union, Canada, and the UN are all directing attention on environmental best practices to protect global resources and have in fact been ahead of the US in this area. To date, the majority of available information on environmental impacts from remedial systems have focused on listing the limitations of the remedial systems. Examples of additional information include Sustainable Remediation Forum (SuRF) UK, Contaminated Land: Applications in Real Environments, and the Network for Industrially Contaminated Land in Europe.
What are the advantages of Green and Sustainable Remediation?
Green and sustainable remediation results in effective clean-ups while minimizing the environmental and energy "footprints" of site remediation, reducing contamination consistent with protection of human health and the environment and regulatory requirements. Sustainable remediation practices emphasize the need to more closely evaluate core elements of a clean-up project in several areas such as the following:
- Energy requirements
- Air emissions
- Water requirements and associated impacts on water resources
- Impacts on land and ecosystems
- Material consumption and waste generation
- Impacts on long-term stewardship of a site
How can I integrate Green and Sustainable Remediation concepts into my environmental restoration project?
Historically, the approach to contaminated sites did not fully consider sustainability concepts when making remedial decisions. One way to address this issue is through the application of tools or calculators that measure the sustainability of remediation technologies according to certain metrics. To aid environmental professions in incorporating sustainability concepts into their remediation decision-making process, AFCEE developed, tested, and released the Sustainable Remediation Tool (SRT). The SRT is designed to evaluate particular remediation technologies on the basis of sustainability metrics. This easy-to-use tool, using Microsoft Office Excel®, facilitates sustainability planning and evaluation, which is intended to aid environmental professionals in achieving goals Remedial Process Optimization (RPO) goals and complying with Executive Order 13423. The SRT was released by AFCEE for free download on 1 May 2009. More information about the SRT can be found online.
As is the intention of the SRT to achieve remedial action goals with the least impact to the environment, several considerations should be included in the design of the project. For instance, GHG emissions can be reduced. GHGs include carbon dioxide, methane, nitrous oxide, fluorocarbons, and sulfur hexafluoride. However, the most frequently discussed and most commonly encountered in remediation is carbon dioxide (CO2). CO2 is a product of the complete combustion of petroleum hydrocarbons. Any process that uses petroleum or coal as a fuel for combustion (i.e., oxidation) will generate GHGs. Remediation activities that intensively use fuel will result in increased GHG emissions. A green and sustainable approach to remediation will consider the production of GHGs. Example activities for reducing greenhouse gases include the following:
Selecting power machinery and equipment that operate using clean fuels Retrofitting diesel engines to operate heavy equipment Generating electricity from byproducts such as methane gas or secondary materials Using renewable energy sources, such as solar, wind, and methane to power remediation activities Periodically evaluating and optimizing energy efficiency of equipment with high energy demands
Consumption of energy, including fuels and electricity, is often a significant component of a cleanup remedy. Utilizing remedies that reduce energy consumption will increase the sustainability of a project. An added benefit may also be that the life-cycle cost-to-complete may be reduced. Green and sustainable ways to reduce energy consumption include the following:
- Selecting passive remedies (e.g., bioremediation, phytoremediation, MNA)
- Replacing energy intensive remedies such as pump-and-treat with less intensive remedies such as a bioremediation or MNA
- Treating in-situ rather than transporting large volumes of waste that require additional energy
- Substitute a fuel-based energy source with one that uses wind turbines or solar energy to provide the energy source
- Participate in power generation or purchasing partnerships offering electricity from renewable resources
- Operating equipment at low-usage times
Remedial projects often impact and or use the very resources we are trying to protect. For example, remedies often require large amounts of water. Selecting a remedy that minimizes the amount of water required or minimizes wasting water is one way to preserve natural resources. Others include the following:
- Reuse/recycle deconstruction and demolition materials
- Utilize water conservation methods by minimizing fresh water consumption and maximizing water reuse
- Retain native vegetation and soils
- Use native vegetation requiring little or no irrigation
- Protect water resources from runoff and contamination
- Maintain engineering and institutional controls on site where waste is left in place
- Incorporate natural systems to manage storm water, like green roofs, landscaped swales, and wetlands.
Waste is often a by-product of remediation, including investigation derived waste. In addition, some aspects of remediation include the use of potential pollutants which, arguably, could be extended to petroleum-based fuels. Often, the production of these pollutants themselves generates toxic waste which may be considered a by-product of the remediation process. A green and sustainable remedy should endeavor to minimize the usage of these chemicals against environmental benefits. Considerations include the following:
- Reclaiming treated water for beneficial use such as irrigation
- Minimizing dust export of contaminants by spraying with reclaimed water
- Preventing impacts such as nutrient loading on water quality in nearby water bodies
- Minimizing bioavailability of contaminants through adequate contaminant source and plume controls
- Using technologies designed to minimize waste generation
Air Force Applications of Green and Sustainable Remediation
Applying sustainability metrics in the Air Force environmental restoration program (ERP) is not a new endeavor. The Air Force ERP has historically focused on cost, risk reduction, compliance with existing laws, and other metrics. However, sustainable approaches and technologies have been investigated and promoted for years throughout the Air Force. Some treatment technologies are inherently sustainable and generally considered "green." While the goal of the Air Force ERP has always been to reduce remediation system costs and timeframes while being protective of human health and the environment, the focus has been on working with and leveraging Mother Nature. Over 50% of the current Air Force remediation systems in place are considered green. Example technologies include phytoremediation, liquid non-aqueous phase liquid (LNAPL) recovery, passive in situ treatment, wetlands, enhanced bioremediation, monitored natural attenuation, biowalls, and passive sampling. The AFCEE Technology Transfer web site provides a great deal of information on these technologies.
In addition to some remediation technologies being inherently sustainable, there are various approaches applied throughout the Air Force ERP that are sustainable themselves. These include the Environmental Restoration Program - Optimization (ERP-O) initiative, the Long-term Monitoring Optimization (LTMO) program, groundwater models, Performance-based Management (PBM), and contract regionalization. Together, these programs and initiatives optimize existing remediation and monitoring systems, and provide holistic and systematic results-based assessment of restoration programs to expedite site closure.
Building upon the Air Force history of applying remediation technologies and approaches that are inherently green and sustainable, the Air Force is beginning to purposefully analyze sustainability as part of selection criteria for new remediation systems as well as for optimization. The following are some brief examples of where sustainability has been introduced into Air Force ERP efforts.
Travis AFB, CA
Travis AFB in California has approached sustainability in their ERP in a holistic manner. In partnership with the AFCEE, they are evaluating the use of an in situ bioreactor in a source zone. This is in place of a dual-phase extraction system; recirculation for carbon distribution is done via a solar-powered pump. US EPA Region 9 has also chosen this site and technology as a case study for green remediation. Down gradient from the in situ bioreactor is a phytoremediation plot, also done in partnership with AFCEE. This technology harnesses Mother Nature and is addressing the dissolved phase portion of the chlorinated solvent contamination at the site. Travis AFB also recently recieved permission for base-wide application of passive diffusion bag samplers, and is using solar-powered extraction pumps and weather stations at other sites on the base. And much of this work appears to be successfully achieved in a performance-based contract (PBC) environment. For more information on this example of green and sustainable remediation, contact the AFCEE Technology Transfer Office at 210-395-8431, afcee.td.awag@us.af.mil.
Altus AFB, OK
Altus AFB, Oklahoma, is one of the leading Air Force installations in the application of enhanced in situ bioremediation. Altus AFB was the first site where a solar-powered in situ bioreactor was demonstrated and evaluated to address source zone contamination with chlorinated solvents in lieu of a soil vapor extraction system. Altus AFB is also the site of the largest biowalls to date to address chlorinated solvent contamination in groundwater. Over a mile of biowall using mulch and compost was installed to treat and prevent off-base contaminant migration. The biowall is being studied by the base and regulators as a replacement for pump and treat. These two green remediation technologies serve as case studies in the AFCEE Technical Protocol for Enhanced Anaerobic Bioremediation Using Permeable Mulch Biowalls and Bioreactors and is being included in the Interstate Technology & Regulatory Council's Permeable Reactive Barrier (PRB) Technical & Regulatory document. For more information on this example of green and sustainable remediation, contact the AFCEE Technology Transfer Office at 210-395-8431, afcee.td.awag@us.af.mil.
Massachusetts Military Reservation (MMR)
The MMR has for some time been conducting energy audits and sustainability assessments of its ERP. The MMR has eight pump-and-treat systems that remediation 15 to 16 million gallons per day. This equates to77 million kWh, costing $9.6 million from 2001 to 2007, and $2 million in 2007 alone. This usage also equates to a total of 54,570,560 lbs CO2 produced, 2,2208 pounds of volatile organic carbon (VOCs), and could power approximately 1,000 homes annually.
In an effort to reduce the environmental footprint of the pump-and-treat systems at MMR, a wind turbine is being built to power groundwater cleanup. The projected cost is $4.6M, and it will produce approximately 3,810 MWh. The installation of the wind turbine will offset air emissions from the commercial pump-and-treat plants, and provide 25% of the ERP electrical needs while reducing 25 to 30% of the air emissions. It is anticipated that MMR will see payback from the wind turbine in 6 to 8 years; start up is projected for September 2009. For more information on this example of green and sustainable remediation, contact the AFCEE Technology Transfer Office at 210-395-8431, afcee.td.awag@us.af.mil.
162nd Fighter Wing, Tucson, AZ
In addition to active Air Force installations implemeting green and sustainable remediation, the Air National Guard (ANG) has performed sustainability assessments of its ERP. At an installation in Tucson, Arizona, a groundwater extraction, treatment and recharge system (GWETRS) (essentially a large pump and treat) extracts 658 million gallons to remove 35 pounds (or 3 gallons) of trichloroethene (TCE). This equates to 1 gallon of TCE removed for every 219 million gallons of groundwater extracted. In addition, most of the wells in the GWETRS are below MCL with the highest concentration at 8.4 ug/L TCE. The average monthly energy consumption of the GWETRS is 22,000 kWh or 265,000 kWh per year. This equates to almost 3% of the entire installation's annual energy consumption.
The ANG's sustainability assessment of the GWETRS resulted in several recommendations which are currently being evaluated for implementation. These include discontinuing the non-contributing groundwater extraction wells, switching the treatment system from air stripper to granulated activated carbon (GAC), using passive treatment and sampling, reducing the sampling frequency, evaluating solar power for the GWETRS, and assessing ways for recharging the aquifer. For more information on this example of green and sustainable remediation, contact the AFCEE Technology Transfer Office at 210-395-8431, afcee.td.awag@us.af.mil.
References
- US Air Force Infrastructire Energy Strategic Plan, 2008 - This plan explains why the Air Force needs an energy strategy, where the Air Force is headed with its strategy, and the difference an energy strategy will make as the Air Force prioritizes and allocates its resources.
- US Air Force Energy, Environment, Safety and Occupational Health: Managing for Operational Sustainability, 2007 Inaugural Report - This report identifies, compiles and describes existing Air Force Energy, Environmental, Safety and Occupational Health programs, processes and performance information essential to supporting Air Force operations and mission capabilities.
- Executive Order 13423 - Strengthening Federal Environmental, Energy, and Transportation Management
- Executive Order 13514 - Federal Leadership in Environmental, Energy, and Economic Performance.
- Net Energy Ratio of Biofuels, AFCEE, 2009 - The general consensus at present is that ethanol and biodiesel have net energy ratios (NERs) greater than one; i.e., they contain more energy than are used in their production. However, there are dissenting opinions, and the debate is still heated. The results of the more recent NER studies are presented and discussed in this paper.
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