The maturing of the Triad approach: Avoiding misconceptions

Misunderstandings and misconceptions have arisen as the Triad approach has gained wider application. The Triad initiative's ability to catalyze second‐generation cleanup practices will be hampered if inaccurate or incomplete assumptions create persistent confusion about what Triad is or how it works. This article has been prepared by the multi‐agency workgroup responsible for articulating the Triad approach and coordinating national Triad efforts. It serves to address some misunderstandings about key Triad concepts. As an aid to those wishing to learn more, a new Web site (the Triad Resource Center, http://www.triadcentral.org) and a new Triad reference document from the Interstate Technology and Regulatory Council (ITRC) are introduced as sources of explanatory information supporting the Triad approach. © 2004 Wiley Periodicals, Inc.     

Enhanced anaerobic bioremediation in a DNAPL residual source zone: Test Area North case study

An Interstate Technology and Regulatory Council (ITRC) forum was recently held that focused on case studies in which bioremediation of dense nonaqueous‐phase liquids (DNAPLs) was performed. This first case study, the Test Area North (TAN) site of the Idaho National Engineering and Environmental Laboratory, involves a trichloroethene (TCE) residual source area in a deep, fractured basalt aquifer that has been undergoing enhanced bioremediation since January 1999. Complete dechlorination from TCE to ethene was documented within nine months of operation, and sodium lactate injections were shown to enhance TCE mass transfer from the residual source. Since that time, optimization of injection strategies has maintained efficient dechlorination while demonstrating accelerated cleanup at a lower cost by changing to a whey powder amendment that solubilizes DNAPL. © 2006 Wiley Periodicals, Inc.     

Pilot‐scale evaluation using bioaugmentation to enhance PCE dissolution at dover AFB national test site

An Interstate Technology and Regulatory Council (ITRC) forum was recently held that focused on six case studies in which bioremediation of dense nonaqueous‐phase liquids (DNAPLs) was performed; the objective was to demonstrate that there is credible evidence for bioremediation as a viable environmental remediation technology. The first two case studies from the forum have been previously published; this third case study involves a pilot‐scale demonstration that investigated the effects of biological activity on enhancing dissolution of an emplaced tetrachloroethene (PCE) DNAPL source. It used a controlled‐release test cell with PCE as the primary DNAPL in a porous media groundwater system. Both laboratory tests and a field‐scale pilot test demonstrated that bioaugmentation can stimulate complete dechlorination to a nontoxic end product and that the mass flux from a source zone increases when biological dehalorespiration activity is enhanced through nutrient (electron donor) addition and bioaugmentation. All project goals were met. Important achievements include demonstrating the ability to degrade a PCE DNAPL source to ethene and obtaining significant information on the impacts to the microbial populations and corresponding isotope enrichments during biodegradation of a source area. © 2007 Wiley Periodicals, Inc.     

A systematic approach to in situ bioremediation in groundwater

In situ bioremediation (ISB) melds an understanding of microbiology, chemistry, hydrogeology, and engineering into a strategy for planned and controlled microbial degradation of specific contaminants. ISB creates subsurface environmental conditions, typically through reduction oxidation manipulation, which induce the degradation of contaminants via microbial catalyzed biochemical reactions. In turn, the microbes produce enzymes that are utilized to derive energy and that are instrumental in the degradation of target chemicals. To accomplish this chain of events, the type of microorganisms, contaminant, and the geological conditions at the site must be considered. Since in situ conditions are manipulated by engineered means, the most important consideration is the ability to transmit and mix liquids in the subsurface. The Interstate Technology Regulatory Council (ITRC)–ISB Team has recently completed a guidance document that describes a systematic approach to ISB in groundwater. ITRC is a state‐led coalition of more than 40 states working together with industry and stakeholders to achieve regulatory acceptance of environmental technologies. © 2003 Wiley Periodicals, Inc.     

Enhanced reductive dechlorination of PCE in unconsolidated soils

An Interstate Technology and Regulatory Council (ITRC) forum was recently held that focused on six case studies in which bioremediation of dense nonaqueous phase liquids (DNAPLs) was performed. The objective was to demonstrate that there is credible evidence for bioremediation as a viable environmental remediation technology. A discussion of the first case study from the ITRC forum was published in the previous issue of Remediation. This article presents a discussion of the second case study, which involves enhanced reductive dechlorination (ERD) of tetrachloroethene (PCE) in unconsolidated soils—primarily silts and clays with very low permeabilities. The project results indicate that complete reductive dechlorination was achieved and provide encouragement that large amounts of nonaqueous solvent can be brought into the reductive dechlorination treatment process by dissolution and desorption, giving support to the contention that the capacity to attack nonaqueous mass is a prerequisite for any effective treatment of DNAPL source zones. The site geology for this project was relatively unfavorable, and further work is needed to confirm that the ERD technology can economically reach a natural attenuation endpoint for this type of setting. © 2006 Wiley Periodicals, Inc.     

Team approaches to the development of innovative technologies and processes to facilitate remediation

The enactment of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) created a complex liability scheme for owners, operators and prospective purchasers of contaminated properties, particularly brownfields. As the program developed, liability issues related to contiguous property, prospective purchasers, and no further action determinations became barriers to brownfield property redevelopment. The national effort on the cleanup and redevelopment of brownfield sites took on new emphasis with the passing of the federal “Small Business Liability Protection and Brownfields Revitalization Act” in January 2002. This new law provides liability clarifications as well as funding to facilitate the cleanup of brownfield sites. President Bush stated in his 2003 State of the Union address, “In this century, the greatest environmental progress will come about not through endless lawsuits or command‐and‐control regulations, but through technology and innovation.” The subject of this article is the Interstate Technology Regulatory Commission's Brownfield team, its current initiative, goals, and areas of special focus. © 2003 Wiley Periodicals, Inc.     

Incorporating Bioavailability Considerations Into the Evaluation of Contaminated Sediment Sites

In March 2011, the Interstate Technology & Regulatory Council (ITRC) Contaminated Sediments Team published a web‐based Technical and Regulatory Guidance on the concepts, processes, and uses of bioavailability in a risk decision‐making framework at a contaminated sediment site. Bioavailability processes, as defined by the National Research Council (NRC; 2003), are the “individual physical, chemical, and biological interactions that determine the exposure of plants and animals to chemicals associated with soils and sediments.” Bioavailability assessment tools aid in the assessment of human and ecological exposure and development of site‐specific remedial objectives. The guidance provides information on the processes that may affect contaminant bioavailability within sediments to understand exposure within ecological and human receptors; supports the development of conceptual site models (CSMs); and describes available tools (biological, chemical, and physical) and models that are used to measure and characterize the fate and transport and potential bioavailability of contaminants. Case studies, referenced throughout the document, demonstrate the practical application of bioavailability measures. The guidance will describe the proper application of traditional and emerging sediment remediation technologies to support the selection of a remedy that is protective of human health and the environment. © 2013 Wiley Periodicals, Inc.     

Enhanced attenuation: Its place in the remediation of chlorinated solvents

The development and regulatory acceptance of monitored natural attenuation (MNA) as a remedial strategy has forever changed the field of environmental cleanup. MNA is continuing to develop but it is challenged by a lack of a clear definition for the appropriate application of the MNA strategy. This challenge has resulted in the lack of a significant record of restoration and site closure. Environmental professionals face challenges in providing guidance that addresses how to manage these sites when technologies, performance monitoring, and even environmental conditions are subject to further development, refinement, and/or altered perspectives. As our experience and institutional knowledge grows around the implementation of MNA, we have the opportunity to develop “second‐generation” management tools and procedures for optimizing sites utilizing MNA as a part of a comprehensive site management plan. This opportunity is the focus of the Enhanced Attenuation: Chlorinated Organics (EACO) Team of the Interstate Technology Regulatory Council (ITRC). The development of the “second‐generation” tools/procedures has included defining EA and evaluating, through the use of a national survey of state regulators, the experience with MNA and interest in EA. The results of these two efforts formed the basis for developing a framework that provides a “bridge” from active treatment to MNA. © 2007 Wiley Periodicals, Inc.     

Remedial Process Optimization and Ozone Sparging for Petroleum Hydrocarbon‐Impacted Groundwater

A former natural gas processing station is impacted with total petroleum hydrocarbons (TPH) and benzene. Remedial process optimization (RPO) was conducted to evaluate the effectiveness of the historical air sparging/soil vapor extraction (AS/SVE) system and the current groundwater extraction and treatment system. The RPO indicated that both remedial activities offered no further benefit in meeting remediation goals. Instead, an in situ chemical oxidation (ISCO) system was recommended. Ozone was selected, and the results of a bench test indicated that the ozone demand was 8 to 12 mg ozone/mg TPH and that secondary by‐products would include hexavalent chromium and bromate. A capture zone analysis was conducted through groundwater flow modeling (MODFLOW) to ensure containment of the injected oxidant using the existing groundwater extraction system. Results of a pilot study indicated that the optimum frequency of ozone sparging is 60 minutes in order to reach a maximum radius of influence of 20 feet. TPH concentrations within the treatment zone decreased by 97 percent over two months of ozone sparging. Concentrations of hexavalent chromium and bromate increased from nondetect to 44 and 110 mg/L, respectively, during the ozone sparging but attenuated to nondetectable concentrations within three months of system shut down. ©2016 Wiley Periodicals, Inc.     

Risk assessment and accepted regulatory cleanup levels

The determination of cleanup levels at a CERCLA or RCRA site is often the single most important decision made by risk managers. This decision can have a major impact on the costs and time required for remediation, as well as on the selection of remedial technologies. The object of this article is to provide a critical review of the methods used by regulatory agencies and the regulated community to calculate chemical-specific cleanup goals for inactive hazardous waste sites, focusing on those cleanup goals that are designed to protect human health from the effects of chemicals. In addition to this analysis of historical methods that have been used, this article discusses some innovative solutions to the problem of calculating cleanup levels and presents an analysis of controversial topics related to cleanup levels currently under debate by regulatory agencies, industry, environmentalists, and legislative bodies.     

Remediation Technologies Screening Matrix and Reference Guide: Version III

The U. S. Army Environmental Center (USAEC) is leading an effort to update the Remediation Technologies Screening Matrix and Reference Guide, Third Edition under the auspices of the Federal Remediation Technologies Roundtable (FRTR). Its purpose is to create a comprehensive “Remediation Technologies Yellow Pages” for use by those responsible for environmental cleanup. The Guide is being produced as a multiagency cooperative effort published under the FRTR. Members of this effort include USAEC, the U. S. Army Corps of Engineers (USACE), the Naval Facilities Engineering Service Center (NFESC), the Air Force Center for Environmental Excellence (AFCEE), the Environmental Protection Agency (EPA), the Department of Energy (DOE), the Department of the Interior (DOI), and the Interstate Technologies Regulation Cooperative (ITRC). This article provides a comprehensive look at environmental technology information provided in the electronic user-defined Remediation Technologies Screening Matrix and Reference Guide.     

Radiological risks and cleanup costs: A remediation case study

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

Best management practices for environmental restoration programs

Based on a review of hundreds of environmental restoration program optimization reviews, this article describes management tools found in successful and efficient remediation programs. Projects that consistently struggled to achieve their objectives were observed to be missing certain, or to have inadequately used, these tools. The tools are articulated as best practices because when they are present and actively used, project shortcomings were minimal. Priority objectives for site owners and project managers include improving efficiency and effectiveness through performance management, reducing resource usage and energy consumption, ensuring protectiveness, and reducing uncertainty in management decision making. Restoring environmental resources damaged by historic waste management practices began in earnest in the late 1960s and early 1970s with the broad recognition of the problems caused by environmental discharges and spills when wastes are not managed appropriately. Under new regulations, soil and groundwater remediation projects could be, and were, conducted within a defined framework. The number and variety of restoration projects that were launched resulted in a slew of projects progressing through the stages of characterization, decision, and cleanup, and more were added to the cleanup process each year. In the 1990s, the Department of Defense noted that many cleanup efforts were projected to incur substantial operational, maintenance, and monitoring costs for decades into the future. This was correctly perceived as an opportunity to optimize those systems and programs, minimize costs, and reduce health and environmental risks. The best practices outlined in this article address management tools that were identified in optimization efforts that led to effective and efficient environmental remediation projects. © 2010 Wiley Periodicals, Inc.     

Expert software that matches remediation site and strategy

Expert software-based decision support is speeding the process of defining environmental hazards and identifying remedial responses for the U.S. Department of Energy's (DOE) hazardous waste cleanup projects throughout the United States. Pacific Northwest Laboratories' (PNL) Remedial Action Assessment System (RAAS), and associated Technology Information System (TIS), written for Macintosh computers (soon for PC-compatible computers), sort through an encyclopedic data base to help environmental engineers prepare the most appropriate remedial strategy. The system has been available to DOE and other U.S. government engineers since last year and will soon be commercially available.     

Application of the SOLVTM Process: A Total Systems Approach to Environmental Remediation

Commodore Solution Technologies, Inc. has developed an innovative total systems approach to environmental remediation that utilizes a patented chemistry called Solvated Electron Technology (SET^TM). Solvated electron solutions are some of the most powerful reducing agents know. Formed by dissolving alkali and alkaline-earth metals in anhydrous liquid ammonia to produce a solution of metal cations and free electrons, solvated electron solutions are capable of providing reductants of great activity and uniqueness. They provide a highly useful mechanism for the reductive destruction of many organic molecules and are extremely effective in the dehalogenation of halogenated organic compounds. Commodore has received a nation-wide EPA operating permit for the nonthermal destruction of PCBs using this process. The SoLV^TM process is a total solution approach that incorporates SET^TM with pre-and post-treatments, when necessary, for environmental cleanup. It is applicable to a broad range of substrates including liquids, solids, soils, and job materials. This article presents results from several pilot, field, and commercial validation studies utilizing the SoLV^TM process.     

Treatment technologies for 1,4‐Dioxane: Fundamentals and field applications

1,4‐Dioxane is a synthetic industrial chemical frequently found at contaminated sites where 1,1,1‐trichloroethane was used for degreasing. It is a probable human carcinogen and has been found in groundwater at sites throughout the United States. The physical and chemical properties and behavior of 1,4‐dioxane create challenges for its characterization and treatment. It is highly mobile and has not been shown to readily biodegrade in the environment. In December 2006, the U.S. Environmental Protection Agency's Office of Superfund Remediation and Technology Innovation (OSRTI) prepared a report titled “Treatment Technologies for 1,4‐Dioxane: Fundamentals and Field Applications.” The report provides information about the chemistry of dioxane, cleanup goals, analytical methods, available treatment technologies, and site‐specific treatment performance data. The information may be useful to project managers, technology providers, consulting engineers, and members of academia faced with addressing dioxane at cleanup sites or in drinking water supplies. This article provides a synopsis of the US EPA report, which is available at http://cluin.org/542R06009 . © 2007 Wiley Periodicals, Inc.     

Accelerating environmental cleanup at DOE sites: Monitored natural attenuation/enhanced attenuation—A basis for a new paradigm

The U.S. Department of Energy is conducting a project to accelerate remediation through the use of monitored natural attenuation and enhanced attenuation for chlorinated ethenes in soils and groundwater. Better monitoring practices, improved scientific understanding, and an advanced regulatory framework are being sought through a team effort that engages technology developers from academia, private industry, and government laboratories; site cleanup managers; stakeholders; and federal and state regulators. The team works collaboratively toward the common goals of reducing risk, accelerating cleanup, reducing cost, and minimizing environmental disruption. Cutting‐edge scientific advances are being combined with experience and sound environmental engineering in a broadly integrated and comprehensive approach that exemplifies socalled “third‐generation R&D.” The project is potentially a model for other cleanup activities. © 2004 Wiley Periodicals, Inc.     

Trends In Regulatory Acceptance Of Risk-Based Cleanup Goals And Natural Attenuation For Site Closure

Since 1994, there has been a significant regulatory shift toward risk-based cleanup standards based on the site-specific risk of the more toxic and mobile compounds; namely, benzene, ethyl benzene, toluene, and xylene (BTEX). This regulatory shift has been accompanied by a growing acceptance of natural attenuation as an important component of petroleum site remediation. This article briefly reviews regulatory progress toward risk-based remediation and describes the successful application of risk-based corrective actions (RBCAs) at two fuel contaminated sites on Air Force installations. By developing site-specific cleanup goals, and combining natural attenuation, source reduction, and land use controls, innovative risk-based closure plans have been implemented on these sites.     

Full‐scale in‐situ biobarrier demonstration for containment and treatment of MTBE

The Naval Facilities Engineering Service Center (NFESC), Arizona State University, and Equilon Enterprises LLC are partners in an innovative Environmental Security Technology Certification Program cleanup technology demonstration designed to contain dissolved MTBE groundwater plumes. This full‐scale demonstration is being performed to test the use of an oxygenated biobarrier at Naval Base Ventura County, in Port Hueneme, California. Surprisingly, few cost‐effective in‐situ remedies are known for the cleanup of MTBE‐impacted aquifers, and remediation by engineered in‐situ biodegradation was thought to be an unlikely candidate just a few years ago. This project demonstrates that MTBE‐impacted groundwater can be remediated in‐situ through engineered aerobic biodegradation under natural‐flow conditions. With respect to economics, the installation and operation costs associated with this innovative biobarrier system are at least 50 percent lower than those of a conventional pump and treat system. Furthermore, although it has been suggested that aerobic MTBE biodegradation will not occur in mixed MTBE‐BTEX dissolved plumes, this project demonstrates otherwise. The biobarrier system discussed in this article is the largest of its kind ever implemented, spanning a dissolved MTBE plume that is over 500 feet wide. This biobarrier system has achieved an in‐situ treatment efficiency of greater than 99.9 percent for dissolved MTBE and BTEX concentrations. Perhaps of greater importance is the fact that extensive performance data has been collected, which is being used to generate best‐practice design and cost information for this biobarrier technology. © 2001 John Wiley & Sons, Inc.     

Using risk assessment to achieve cost-effective property transfers and site closures for former UST sites

Risk assessment has been increasingly applied as a tool in making risk management decisions that affect cleanup of contaminated sites, property transactions, and liability issues. As a site-specific evaluation, risk assessment takes into account the unique characteristics and intended future uses for site property in evaluating chemical concentrations which may remain in place without risk to public health and the environment. The results of a risk assessment can be used to determine reuse options for a property, facilitate site closure, and reduce liabilities (Copeland and Robles, 1994; Copeland et al., 1993a). This article describes the risk assessment process, the role of risk assessment in determining the need for remedial action and identifying site-specific cleanup goals, and the cost effectiveness of applying risk assessment in remedial decisions. Because of the prevalence of former UST sites throughout the United States, this article focuses on risk assessment and remediation of UST sites. However, the process can be applied at sites where other chemicals have been released. Three case studies are presented to illustrate the application of risk assessment in achieving cost-effective site closure at sites containing leaking underground storage tanks.