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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization 1 Challenges of Ground Water and Soil Cleanup Over the past quarter century, the United States has placed a high priority on cleaning up sites where contaminants have leaked, spilled, or been disposed of in the soil and ground water. Anywhere from 300,000 to 400,000 contaminated sites are scheduled for cleanup in the coming decades, at an estimated total cost as high as $500 billion to $1 trillion (National Research Council, 1994; Russell et al., 1991). The Office of Management and Budget estimates that the costs of remediation at contaminated sites on property owned by the Departments of Defense, Energy, Interior, and Agriculture and the National Aeronautics and Space Administration will total between $234 and $389 billion over the next 75 years (Federal Facilities Policy Group, 1995). National spending on waste site remediation totaled an estimated $9 billion in 1996 alone, as shown in Figure 1-1. As cleanup at waste sites has proceeded, it has become increasingly recognized that despite the the billions of dollars invested, conventional remediation technologies, especially for sites with contaminated ground water, are inadequate. For example, a 1994 National Research Council (NRC) study of conventional ground water cleanup systems at 77 contaminated sites determined that ground water cleanup goals had been achieved at only 8 of the sites and that full achievement of cleanup goals was highly unlikely with the in-place technologies at 34 of the 77 sites (NRC, 1994; MacDonald and Kavanaugh, 1994, 1995). A 1995 review by the Congressional Budget Office found that using nonconventional methods for waste site investigation and cleanup could cut costs by 50 percent or more (CBO, 1995). Based on such findings, it is clear that new technologies are needed to restore the nation's contaminated sites. The limitations of conventional ground water cleanup systems are now well recognized by regulators, consultants, engineers, and others involved in waste
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization FIGURE 1-1 Estimated spending on environmental remediation (in billions of dollars) in 1996 in various sectors of the U.S. economy. Total spending was estimated at $9 billion. SOURCE: Adapted from information in Environmental Business International, 1995. site remediation. Indeed, federal and state agencies and many private industries have launched numerous initiatives to promote the development and use of innovative remediation technologies. These initiatives range from issuance of an official EPA policy titled "Initiatives to Promote Innovative Technology in Waste Management Programs" (Laws, 1996), to development of the Ground Water Remediation Technologies Analysis Center (which provides on-line information on new technologies) (GWRTAC, 1995), to establishment of government/industry partnerships such as the Remediation Technologies Development Forum. The EPA has an office, the Technology Innovation Office, dedicated to finding ways to promote use of innovative remediation technologies. These and other initiatives have led to increased research on innovative remediation technologies. While there has been major progress in research and increased use of new technologies in some situations, use of new ground water cleanup technologies at major contaminated sites is still limited. For example, as of 1996, conventional pump-and-treat methods were being used for ground water cleanup at 93 percent of Superfund sites (EPA, 1996). The reasons for the limited use of new ground water cleanup technologies are complex. They include regulatory programs that inhibit market development, lack of consistent data on technology cost and performance, and the uniqueness of each contaminated site. The lack of commercially available technologies that can restore contaminated ground water at reasonable cost has led to increasing pressure to limit waste cleanups to sites that pose immediate risks to human health, rather than applying costly and potentially ineffective conventional cleanup systems. The American Society for Testing and Materials (ASTM) in 1995 issued a standard entitled "Standard Guide for Risk-Based Correction Action Applied at Petroleum-Re-
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization lease Sites" (known as RBCA) that outlines a procedure for limiting the cleanup of underground storage tank sites to those posing immediate risks (ASTM, 1995). RBCA is a process for determining site-specific risk factors and setting site-specific cleanup goals. The standard is controversial because of uncertainty in the risk assessment methods it employs, but many states are implementing it in cleanups of petroleum contamination from underground storage tanks. In addition, many organizations are now lobbying to implement a similar ASTM RBCA standard for chemical release sites, which is under development, at major contaminated sites regulated under federal programs. If RBCA were widely applied at all types of contaminated sites, a large fraction of sites currently slated for r remediation would not be actively cleaned up (Begley, 1996), and those that are would be cleaned up to less stringent standards. While the lack of cost-effective, commercially available remediation technologies has led to increased use of RBCA as a means for limiting site cleanups, the development of effective technology can cause a counter trend. When technology becomes available to address contamination at affordable costs, pressure to apply the technology on a widespread basis will increase. When contaminants are left in place, those responsible for the contaminated site must bear the cost of continued liability should contamination escape from the site into surrounding communities. Predicting the potential for such contaminant migration off site is subject to significant uncertainties, so that the full costs of this long-term liability are difficult to calculate. Further, maintaining the site to prevent exposure to the contamination may involve long-term costs. Costs are also associated with decreased property values and difficulty in selling property when significant contamination remains in place. Finally, leaving contamination in place is unacceptable to members of some communities near contaminated sites. Affordable remediation technologies that can remove the bulk of contaminant mass from the subsurface at contaminated sites would reduce the long-term risks, liabilities, and costs associated with these sites. This report focuses on how to harness market forces to stimulate development of new, affordable remediation technologies and how to standardize testing, evaluation, and cost comparison of innovative remediation technologies. Standardizing technology testing and data collection is an important step in commercializing innovative remediation technologies and in reducing costs because current data sets are often inadequate for extrapolating data from one site to the design of a cleanup system at another site. As explained in Chapter 2 of this report, a necessary prerequisite to the establishment of standardized testing programs for remediation technologies is assurance that strong market forces are in place to stimulate demand for new technologies. No amount of government promotion of technology testing will be fully effective if the market demand for innovative technologies is lacking. This report is the culmination of a two-and-a-half-year study by the NRC's Committee on Innovative Remediation Technologies. The committee was ap-
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization pointed by the NRC in 1994 to develop testing and performance standards for subsurface cleanup technologies and to examine other issues related to commercialization of these technologies. The members of the committee, who are the authors of this report, included environmental consultants, environmental researchers from academia, and experts in environmental policy, patent law, technology financing, and public opinion. In conducting its study, the committee consulted with a wide range of stakeholders involved in the testing of subsurface cleanup technologies, including federal and state regulators, industry groups, heads of start-up technology companies, and venture capitalists. This chapter provides an overview of the sources of ground water and soil contamination, the limitations of conventional remediation technologies, and the frequency of use of innovative remediation technologies. Chapter 2 assesses the remediation technology market and recommends market-based approaches for strengthening it. Chapter 3 defines the current state of the practice in ground water and soil cleanup, identifying areas where innovation is needed. Chapter 4 outlines benchmark criteria for evaluating ground water and soil cleanup technologies to satisfy the concerns of all stakeholders. Chapter 5 recommends testing strategies for evaluating technology performance. Chapter 6 describes how to compare the costs of alternative technologies. SOURCES OF GROUND WATER AND SOIL CONTAMINATION Accidental spills, routine washing and rinsing of machinery and chemical storage tanks, leaks in industrial waste pits and municipal and industrial landfills, and a variety of other human activities (see Table 1-1 and Figure 1-2) can release contaminants to soil and ground water (see Box 1-1). The most common types of contaminants found at waste sites are chlorinated solvents, petroleum hydrocarbons, and metals (NRC, 1994). Chlorinated solvents, such as trichloroethylene and perchloroethylene (PCE), are used for purposes ranging from dry cleaning of consumer goods to degreasing of industrial manufacturing equipment and cleaning of military aircraft. Petroleum hydrocarbons commonly found in ground water include the components of gasoline (benzene, toluene, ethylbenzene, and xylene, together known as BTEX), as well as other fuels. Because of the widespread use of both chlorinated solvents and petroleum hydrocarbons, it is not surprising that they are found in the ground water at hundreds of thousands of contaminated sites across the country. Other contaminants found in ground water and soil at many sites are polycyclic aromatic hydrocarbons, created from combustion, coal coking and processing, petroleum refining, and wood treating operations; polychlorinated biphenyls (PCBs), once widely used in electrical transformers and capacitors and for a variety of other industrial purposes; pesticides, used for agriculture; metals, from metal plating and smelting operations, mines, and other industrial activities; and radioactive compounds, used in the manufacture of nuclear weapons at Department of Energy (DOE) facilities.
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization TABLE 1-1 Ground Water Contamination Sources Sources designed to discharge substances Subsurface percolation (e.g., septic tanks and cesspools) Injection wells Hazardous waste Hazardous waste (e.g., brine disposal and drainage) Nonwaste (e.g., enhanced oil recovery, artificial recharge, solution mining, and in situ mining) Irrigation practices (e.g., return flow) Land application Wastewater (e.g., spray irrigation) Wastewater byproducts (e.g., sludge) Hazardous waste Sources designed to store, treat, and/or dispose of substances; discharge through unplanned release Landfills Industrial hazardous waste Industrial nonhazardous waste Municipal sanitary Open dumps, including illegal dumping Residential (or local) disposal Surface impoundments Waste tailings Waste piles Material stockpiles Graveyards Animal burial sites Above-ground storage tanks Underground storage tanks Containers Open burning and detonation sites Radioactive disposal sites Sources designed to retain substances during transport or transmission Pipelines Material transport and transfer operations Nonhazardous waste (e.g., brine disposal and drainage) Sources discharging substances as consequences of other planned activities Irrigation practices (e.g. return flow) Pesticide applications Fertilizer applications Animal feeding operations De-icing salts applications Urban runoff Percolation of atmospheric pollutants Mining and mine drainage Sources providing pollution conduits or inducing discharge through altered flow patterns Production wells Oil (and gas) wells Geothermal and heat recovery wells Water supply wells Other wells Monitoring wells Exploration wells Construction excavation Drains Naturally occurring sources, with discharge created and/or exacerbated by human activity Ground water-surface water interactions Natural leaching Salt water intrusion/brackish water upcoming (or intrusion of other poor-quality natural water) Source: Adopted from Reichard et al. (1990). As shown in Table 1-1, some contaminants are released directly to ground water, for example in water injection wells, while others are released to the soil. When released to the soil, contaminants will migrate through the soil and may contaminate the underlying ground water (see Box 1-2). Some contaminants may dissolve in the ground water as it percolates through the soil. Others may dissolve in the gases contained in soil pores and spread before dissolving in the ground water. Contaminants also may be transported as a separate, nonaqueous-phase
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization FIGURE 1-2 Classification of ground water contamination sources according to source geometry. SOURCE. Reprinted with permission, from Spitz and Moreno (1996). 1996 by John Wiley & Sons.
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization BOX 1-1 The Underground Environment The underground environment consists of layers of granular materials (such as sand and gravel), clay, and solid rock. Ground water flows through the pores and fractures in these materials, in formations known as aquifers. There are two kinds of aquifers: consolidated and unconsolidated (see Figures 1-3 and 1-4). Consolidated aquifers consist of essentially solid rock permeated with cracks and crevices through which water flows. Unconsolidated aquifers consist of uncemented granular materials; water and other fluids flow through the pore spaces among these materials. Below the water table, all of the pores and crevices in an aquifer are saturated with water. This region is technically known as the "saturated" zone. Above the water table, the pores and crevices are only partially filled with water. This region is known as the "unsaturated" or "vadose" zone. Geologic processes can produce aquifers with highly variable (heterogeneous) hydraulic and geochemical properties. For example, sand and gravel aquifers may contain lenses of clay. Even in relatively homogeneous aquifers, the grain size of aquifer materials may vary with location across a small area. Because of the nonuniformity of aquifer formations, the flow of water and other liquids through the subsurface can be difficult to predict. liquid (known as a NAPL) that is immiscible in water and therefore travels separately from the water. Other contaminants can sorb to mobile colloidal particles or form complexes with molecules of natural organic matter present in the water and be transported with these particles and complexes. The fate of contaminants once released to the soil or ground water is extremely difficult to predict for a variety of reasons. Contaminated fluids (water, gas, and NAPLs) will flow preferentially through soil pathways offering the least resistance, and the locations of these pathways may be very difficult to determine. Contaminants also may sorb to the soil, or, in the case of metals, precipitate. NAPL contaminants may become entrapped in soil pores, leaving residual-phase contamination. Once the soil pores are saturated with NAPLs, the remaining NAPL will migrate downward to the water table. If the NAPL is less dense than water it may form a pool at the surface of the water table. If the NAPL is more dense than water, it will continue its downward migration—in some cases in the form of narrow, viscous "fingers" that are extremely difficult to locate—until it encounters an impermeable barrier (NRC, 1994). Under each of these circum-
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization Coal tar recovered from a ground water monitoring well. This dense nonaqueousphase liquid can contaminate water with polycyclic aromatic hydrocarbons and other aromatic contaminants. The liquid is extremely difficult to locate and remove once it migrates into the subsurface. Courtesy of Richard Luthy, Carnegie Mellon University. stances, the contaminants will leave a reservoir that will serve as a long-term source of ground water contamination. While contaminant source areas may be small and present no immediate hazard to human health or the environment, contaminants from these source areas will dissolve very slowly in the passing ground water, forming a plume and spreading. The plume can migrate large distances and contaminate drinking water wells, wetlands, and receiving waters. The size and location of the plume depend on the location of the contaminant sources, the path of natural ground water flow, and the various subsurface mechanisms that can entrap or transform the contaminant. The speed at which the plume will move depends on the rate of ground water flow and on contaminant retention and transformation mechanisms. Generally, the average ground water flow rate will be the maximum possible average rate of plume movement. Ground water flow rates vary widely from site to site depending on local hydrogeology, with values ranging from less than 1 mm per day to more than 1 m per day. Other processes occurring in the subsurface (see Boxes 1-3 and 1-4) cause the contaminant to move more slowly than the ground water. As an example of the complexity of contaminant flow paths, Figure 1-5 shows the migration of PCE at a hypothetical site. The black areas contain undissolved PCE that has migrated separately from the ground water. The shaded por-
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization FIGURE 1-3 Simplified schematic of ground water flow in an unconsolidated aquifer. The flow lines indicate travel times to various parts of the subsurface, with longer travel times indicated by flow lines reaching deeper into the subsurface. SOURCE: Heath (1983) as reprinted in NRC, 1994. FIGURE 1-4 Simplified schematic of ground water flow in a consolidated aquifer. As the flow lines indicate, the direction of ground water flow in such aquifers depends on the locations of the fractures and thus is often tortuous and difficult to predict. SOURCE: From Heath (1980), as reprinted in NRC, 1994.
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization BOX 1-2 Contaminant Transport Mechanisms Contaminants may move underground by one or a combination of several mechanisms, depending on their properties: 1. Vapor-phase transport: Vapors of volatile contaminants may spread through the pore spaces in the soil above the water table and then either dissolve in water in soil pore spaces or in infiltrating rain water. The volatility of contaminants, and thus the extent to which they will migrate in the vapor phase, varies by many orders of magnitude. 2. Aqueous-phase transport: Contaminants may dissolve in and be transported with the flowing ground water. The rate of dissolution depends on contaminant solubility, which varies among contaminants by many orders of magnitude; the extent of contaminant contact with water; and contaminant reactions with solids in the aquifer. 3. Nonaqueous-phase liquid (NAPL) transport: contaminants, including chlorinated solvents and petroleum products, enter the subsurface in the form of an oily liquid, known as a NAPL. NAPLs do not mix readily with water and therefore flow separately from ground water. If the NAPL is more dense than water (known as a DNAPL), it will tend to sink once it reaches the water table. If the liquid is less dense than water (known as an LNAPL), it will tend to float on the water table. 4. Facilitated transport: Contaminants may sorb to mobile colloidal particles or be incorporated into large complexes of natural organic matter and be transported with these particles or complexes in the flowing ground water. Contaminants associated with colloidal particles and organic complexes can travel with the ground water at rates much faster than would be predicted based upon contaminant transport models that neglect to consider these reactions. Such reactions are especially significant for metals and radionuclides; these contaminants generally have limited solubility over the pH range encountered in most ground waters, but sorption and complexation reactions can greatly increase the quantity of contaminant in the water. As an example of these transport pathways, Figure 1-5 illustrates the possible fate of perchloroethylene in an aquifer consisting of strata of sand and fractured clay.
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization BOX 1-3 Contaminant Retention Mechanisms A variety of physical and chemical processes can retain contaminants in the subsurface. While the interactions governing retention vary with contaminant and site characteristics, the effect on contaminant transport in all cases is the same: a retardation in the average rate of movement of the contaminant with respect to the ambient ground water flow. Key mechanisms for retention include the following: • Sorption and ion exchange: Contaminants may sorb to solid materials in the subsurface. Contaminants such as heavy metals, polycyclic aromatic hydrocarbons, PCBs, and some pesticides have a strong tendency to sorb to soil under chemical conditions commonly found in the subsurface. • NAPL entrapment: As illustrated in the example for PCE, small globules of NAPLs can become trapped in porous materials by capillary forces. The amount of entrapped compound is quantified technically as ''residual saturation," the ratio of the entrapped volume of NAPL to the total pore volume. • Diffusion into micropores: Dissolved contaminants may migrate by molecular diffusion into tiny micropores within aggregates of geologic materials. • Entrapment in immobile zones: Contaminants may migrate into geologic zones where the ground water flow rate is very slow, essentially zero. • Precipitation: Depending on the pH and other chemical characteristics of the ground water, metal contaminants may precipitate, forming immobile solids. tions of the figure show the movement of the plume of dissolved PCE from the source areas containing undissolved PCE. TYPES OF CONTAMINATED SITES In general, hazardous waste sites can be grouped into the following seven categories (NRC, 1994): closed or abandoned waste sites designated for cleanup under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly known as Superfund;
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization TABLE 1-2 Number of Hazardous Waste Sites Where Ground Water May Be Contaminated Source of Estimate Site Category EPA, 1993 Russell et al., 1991 Office of Technology Assessment, 1989 CERCLA National Priorities List 2,000 3,000 10,000 RCRA corrective action 1,500– 3,500 NA 2,000– 5,000 Leaking underground storage tanks 295,000 365,000 300,000– 400,000 Department of Defense 7,300 (at 1,800 installations) 7,300 8,139 Department of Energy 4,000 (at 110 installations) NA 1,700 Other federal facilities 350 NA 1,000 State sites 20,000 30,000 40,000 Approximate total 330,000 NA 360,000–470,000 NOTE: The numbers presented in this table are estimates, not precise counts. In addition, at some of these sites, ground water may not be contaminated. For example, the EPA (1993) estimates that ground water is contaminated at 80 percent of CERCLA National Priorities List sites. There is also some overlap in site categories. For example, 7 percent of RCRA sites are federal facilities, and 23 DOE sites are on the CERCLA National Priorities List (EPA, 1993). NA indicates that an estimate comparable to the other estimates is not available from this source. SOURCE: NRC, 1994. site. State and local governments around the nation are currently creating programs to encourage redevelopment of brownfield sites, and these brownfield programs have become major drivers in the remediation marketplace, along with the cleanup programs listed in Table 1-2. It is important to note that the complexity of waste sites varies enormously depending on the source of the contamination and the geologic conditions at the site. Most of the sites shown in Table 1-2 are leaking underground storage tank sites. If the contamination is from a single tank at a gas station, the site will be relatively easy to clean up, especially if it is located in an area with relatively homogeneous geology. On the other hand, contaminated sites at major DOD and DOE installations, as well as at many industrial facilities, may contain complex mixtures of chlorinated solvents, fuels, metals, and, at DOE facilities, radioactive
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization substances. These contaminants may have leaked, spilled, or been disposed of into the ground water over several decades, creating contamination problems that, in turn, will require decades to clean up. LIMITATIONS OF CONVENTIONAL REMEDIATION TECHNOLOGIES As is now widely recognized, conventional methods for cleaning up ground water and soil at hazardous waste sites have met with limited success. Conventional technologies for cleaning contaminated ground water are based on the principle that if enough water is pumped from the site, the contaminants will eventually be flushed out. These conventional technologies are known as "pump-and-treat" systems (see Figure 1-6) because they pump water from the site and treat it to remove the contamination. For several reasons, the flushing process employed by pump-and-treat systems has limited effectiveness, especially for cleaning up undissolved sources of contamination beneath the water table. Key contaminant and subsurface properties that interfere with flushing include the following (NRC, 1994; MacDonald and Kavanaugh, 1994, 1995): Immiscibility of contaminants with water: Many contaminants are extremely difficult to flush from the subsurface because of their relatively low solubility in water. Diffusion of contaminants into micropores and zones with limited water mobility: The microscopic pores and zones with limited water mobility into which Excavation of soil at a contaminated site. Courtesy of Fluor Daniel GTI.
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization FIGURE 1-6 Conventional pump-and-treat system for cleanup of contaminated ground water. SOURCE: From Mercer et al. (1990) as reprinted in NRC, 1994. contaminants may diffuse are extremely difficult to flush with water because of their small size and inaccessibility. Sorption of contaminants to subsurface materials: Flushing out contaminants that have sorbed to underground soils is a very slow process because of the slow rate of desorption. Heterogeneity of the subsurface: Prediction methods for determining the routes of travel of contaminants and of water used to flush out contaminants are not always accurate because of the heterogeneous nature of the subsurface. Because of the difficulty of flushing contaminants from the subsurface, the NRC concluded in its 1994 study that pump-and-treat systems would be unable to fully restore many types of contaminated sites (see Box 1-5). Historically, the conventional approach to soil cleanup has been to incinerate the contaminated soil on site or off site, to solidify it in place with cementing agents, or to excavate it and dispose of it in a hazardous waste landfill. The public often objects to incineration because of the air pollution it can create, and cleanup of many Superfund sites has been halted because of such objections. One of many such examples is the Baird & McGuire Superfund site in Massachusetts, where citizens formed a lobbying group, Citizens Opposed to Polluting the Environment, to block installation of an incinerator (MacDonald, 1994). Solidification technologies and excavation, while less controversial, are limited in that they do not clean up the contamination but simply immobilize it or move it elsewhere. All of these traditional remedies, especially incineration and excavation involving transport of the excavated materials, are costly. For example, cleanup of PCB-
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization BOX 1-5 Performance of Conventional Pump-and-Treat Systems In its 1994 study, the NRC developed a scale of 1 through 4, shown in Table 1-3, for categorizing sites according to their difficulty of cleanup with conventional pump-and-treat systems. As shown in the table, the categories are based on the hydrogeology of the site or portion of the site and the chemistry of the contaminants. The 1994 study concluded that while cleanup of sites in category 1 (those with relatively simple geology and contaminant chemistry) to drinking water standards should be feasible with conventional pump-and-treat systems, cleanup of sites in category 4 is unlikely. The study determined that cleanup of sites in categories 2 and 3 may be feasible in some situations but is subject to uncertainties that may prevent the achievement of cleanup goals, especially for sites in category 3. The study included a review of pump-and-treat systems operating at 77 sites chosen based on the availability of information. The distribution of sites was not representative of the distribution of all types of waste sites nationwide because fewer than 10 percent of the 77 sites were service stations, while at least 80 percent of the contaminated sites nationwide are underground storage tank sites (see Table 1-2), and many of these are service stations. However, with the exception of the service stations, the 77 sites were more representative of the types of sites regulated under Superfund and RCRA. Of the 77 sites reviewed in the study, • 2 were in category 1, and cleanup goals had been achieved at 1 of these sites; • 14 were in category 2, and cleanup goals had been achieved at 4 of these sites; • 29 were in category 3, and goals had been achieved at 3 of these sites; and • 42 were in category 4, and cleanup goals were achieved at none of these sites. contaminated soil using conventional methods can cost as much as $2,000 per ton of soil. USE OF INNOVATIVE REMEDIATION TECHNOLOGIES During the 1990s, as the limitations of conventional subsurface remediation technologies have become increasingly clear, innovative technologies have become increasingly common in the cleanup of contaminated soil and of leaking
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization TABLE 1-3 Relative Ease of Cleaning Up Contaminated Aquifers as a Function of Contaminant Chemistry and Hydrogeology Contaminant Chemistry Hydrogeology Mobile, Dissolved (degrades / volatilizes) Mobile Dissolved Strongly Sorbed, Dissolveda (degrades / volatilizes) Strongly Sorbed, Dissolveda Separate Phase LNAPL Separate Phase DNAPL Homogeneous, single layer 1b 1-2 2 2-3 2-3 4 Homogeneous, multiple layers 1 1-2 2 2-3 2-3 3 Heterogeneous, single layer 2 2 3 3 3 4 Heterogeneous, multiple layers 2 2 3 3 3 4 Fractured 3 3 3 3 4 4 a "Strongly sorbed" generally indicates contaminants for which the retardation coefficient is greater than 10. A retardation coefficient of 10 indicates that at any given time, 10 percent of the contaminant is dissolved in the water and 90 percent is sorbed to the aquifer solids. b Relative ease of cleanup, where 1 is easiest and 4 is most difficult. SOURCE NRC, 1994. underground storage tanks containing petroleum products. However, use of innovative technologies is still very rare for cleaning up ground water at major contaminated sites regulated by the Superfund and RCRA programs. Figures 1-7 and 1-8 show the types of technologies used to clean up contaminated soil at Superfund and underground storage tank sites, respectively. As shown in Figure 1-7, innovative technologies have been selected for cleaning up contaminated soil, sludge, and sediments at 43 percent of Superfund sites. However, the number of innovative technologies in use at these sites is limited. Two technologies, soil vapor extraction and thermal desorption, accounted for more than half of the innovative technologies selected. As shown in Figure 1-8, innovative approaches were chosen at approximately 66 percent of underground storage tank sites. However, landfilling is still the predominant remedy for contaminated soil at these sites. Figures 1-9 and 1-10 show the types of technologies used to clean up contaminated ground water at Superfund and underground storage tank sites, respectively. As shown, conventional pump-and-treat systems are the chosen remedy at 93 percent of Superfund sites with contaminated ground water; in situ treatment remedies not involving pump-and-treat systems are used at fewer than 1 percent
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization FIGURE 1-7 Types of technologies used to clean up contaminated soil at Superfund sites. Data for off-site incineration, solidification/stabilization, and other established technologies are based on records of decision for fiscal years 1982 through 1993. Data for innovative technologies and on-site incineration are based on anticipated design and construction activities as of August 1996. A site may use more than one technology, ( ) indicates the number of times this technology was selected or used. "Other" established technologies are soil aeration, open detonation, and chemical neutralization. "Other" innovative technologies are hot air injection, physical separation, contained recovery of oily wastes (CROW™), cyanide oxidation, vitrification, and plasma high temperature metals recovery. SOURCE: Adapted from EPA, 1996. of the sites. At underground storage tank sites, innovative technologies are being used at approximately 43 percent of sites where active remedies (other than intrinsic remediation) have been selected. The greater use of innovative ground water cleanup technologies at underground storage tank sites in comparison to Superfund sites is a function of the relative simplicity of cleaning up these sites in comparison to Superfund sites and the greater regulatory flexibility of the underground storage tank program. Leaking underground storage tanks typically contain petroleum hydrocarbons, which are generally easier to clean up than other types of contaminants (see Chapter 3). In addition, these sites are relatively small in comparison to Superfund sites. Finally, underground storage tank cleanups are regulated by state agencies, and typically there is minimal regulatory oversight in technology selection, allowing greater freedom to choose different types of technologies (see Chapter 2). Comprehensive data such as are available for the Superfund and underground
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization FIGURE 1-8 Types of technologies used to cleanup contaminated soil at under ground storage tank sites. The total number of sites where soil cleanup is under way is approximately 103,000. SOURCE: Adapted from Tremblay et al., 1995. FIGURE 1-9 Types of technologies used to cleanup contaminated ground water at Superfund sites. Pump-and-treat remedy data are based on records of decision for fiscal years 1982 through 1995; in situ treatment data are based on anticipated design and construction activities for August 1996. The total number of sites with remedies for contaminated ground water is 603. The total number of in situ treatment remedies exceeds the total number of sites at which treatment remedies are being implemented because more than one technology is being employed at some sites. SOURCE: Adapted from EPA, 1996.
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization FIGURE 1-10 Types of technologies used to cleanup contaminated ground water at underground storage tank sites. The total number of sites where ground water cleanup is under way is approximately 19,200. SOURCE: Adapted from Tremblay et al., 1995 storage tank programs are not available for the RCRA program or for federal facilities and state cleanup programs. Since the EPA's general policy is to implement Superfund and RCRA cleanups in a similar fashion, it is likely that the use of innovative technologies at RCRA sites is similar to use of innovative technologies in the Superfund program (EPA, 1993). A noncomprehensive review of remedies for contaminated ground water at 15 RCRA sites indicated that pump-and-treat systems were chosen at 14 of the sites. At the fifteenth site, access to contaminated ground water was restricted rather than requiring ground water treatment. At two of the sites, bioremediation systems were chosen to operate in conjunction with the p pump-and-treat systems (Davis, 1995). In an audit of cleanups at federal facilities, the U.S. General Accounting Office found that ''although EPA, Energy and Defense have spent substantial sums to develop waste cleanup technologies, few new technologies have found their way into cleanups" (Guerrero, 1995). BARRIERS TO INNOVATION Since the late 1980s, reports from a variety of organizations have indicated that significant barriers exist to development of remediation technologies for commercial markets. Early reports were produced by a federal advisory commission known as the Technology Innovation and Economics Committee, part of the National Advisory Council on Environmental Policy and Technology. This group, established in 1989, assessed the use of all types of environmental technologies, focusing primarily on pollution prevention and recycling technologies but also
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization considering hazardous waste cleanup technologies. The group concluded that "current environmental statutes and federal regulations do not encourage the development of innovative technological solutions" (EPA, 1989). Similar conclusions emerged from events and reports of a variety of other organizations, including a series of workshops hosted by the EPA's Technology Innovation Office for environmental consultants, government regulators, and regulated industries (EPA, 1990, 1992); a workshop convened by a federal commission known as the Federal Advisory Committee to Develop On-Site Innovative Technologies (the "DOIT" committee) (Federal Advisory Committee to Develop On-Site Innovative Technologies, 1993); and a report issued by the National Commission on Superfund, established to develop a consensus among industries, environmental groups, and government officials about changes needed in the Superfund program (National Commission on Superfund, 1994). Barriers to use of innovative technologies are complex and range from the inherent variability of the subsurface environment, to regulatory obstacles, conservatism on the part of hazardous waste site owners and their consultants, and lack of trustworthy data on technology performance. Much of this report focuses on developing credible data sets that can be used to compare innovative technologies against conventional ones and to transfer technology used at one site to another site without having to repeat all elements of the testing. However, as explained in Chapter 2, market and regulatory barriers must be addressed, as well, in order for a technology testing program to be effective. The technical problems associated with cleanup of contaminated ground water and soil at hazardous waste sites are far from solved, and there is a great deal of room for innovation, provided disincentives to innovate can be eliminated. REFERENCES ASTM (American Society for Testing and Materials). 1995. Standard Guide for Risk–Based Corrective Action Applied at Petroleum–Release Sites. E1739–95. West Conshohocken, Pa.: ASTM. Begley, R. 1996. Risk–based remediation guidelines take hold. Environmental Science & Technology 30(10):438A–441A. Chapelle, F.H. 1992. Ground–Water Microbiology and Geochemistry. New York: John Wiley & Sons. Cohen, R.M., and J.W. Mercer. 1993. DNAPL Site Evaluation. Boca Raton, Fla.: C.K. Smoley. CBO (Congressional Budget Office). 1995. Cleaning Up Defense Installations: Issues and Options. Washington, D.C.: Congressional Budget Office. Davis, H.R. 1995. Unpublished data from the RCRA Corrective Action Program. Washington, D.C.: EPA, Office of Solid Waste.
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization Environmental Business International. 1995. Global Environmental Market and United States Industry Competitiveness Report. San Diego: Environmental Business International. EPA. 1989. Report and Recommendations of the Technology Innovation and Economics Committee: Recommendations for Action on Technology Innovation. Washington, D.C.: EPA, Office of Cooperative Environmental Management. EPA. 1990. Meeting Summary: Workshop on Developing an Action Agenda for the Use of Innovative Remedial Technologies by Consulting Engineers. Washington, D.C.: EPA, Technology Innovation Office. EPA. 1992. Meeting Summary: Project Listen—Enhancing Technologies for Site Cleanup. Washington, D.C.: EPA, Technology Innovation Office. EPA. 1993. Cleaning Up the Nation's Waste Sites: Markets and Technology Trends. EPA 542-R-92-012. Washington, D.C.: EPA, Office of Solid Waste and Emergency Response. EPA. 1996. Innovative Treatment Technologies: Annual Status Report (Eight Edition). E EPA-542-R-96-010. Washington, D.C.: EPA, Office of Solid Waste and Emergency Response. Federal Advisory Committee to Develop On-Site Innovative Technologies. 1993. Regulatory and Institutional Barriers Roundtable: Comment Draft Report from Regulatory Barriers Roundtable, San Francisco, October 20, 1993. Washington, D.C.: EPA, Technology Innovation Office. Federal Facilities Policy Group. 1995. Improving Federal Facilities Cleanup. Washington, D.C.: Council on Environmental Quality, Office of Management and Budget. GAO (General Accounting Office). 1995. Community Development: Reuse of Urban Industrial Sites. GAO/RCED-95-172. Washington, D.C.: GAO. Guerrero, P.F. 1995. Federal Hazardous Waste Sites: Opportunities for More Cost-Effective Cleanups. GAO/T-RCED-95-188. Washington, D.C.: GAO. GWRTAC. 1995. NETAC Selected to Operate National Ground-Water Remediation Technology Center (News Release). Pittsburgh, Pa.: Ground-Water Remediation Technologies Analysis Center (http://www.chmr.com/gwrtac). Heath, R.C. 1980. Basic Elements of Ground-Water Hydrology with Reference to Conditions in North Carolina . U.S. Geological Survey Water Resources Investigations Open-File Report 80-44. Washington, D.C.: U.S. Government Printing Office. Heath, R.C. 1983. Basic Ground-Water Hydrology. U.S. Geological Survey Water Supply Paper 2220. Washington, D.C.: U.S. Government Printing Office. Laws, E.P. 1996. Letter to Superfund, RCRA, UST, and CEPP national policy managers, Federal Facilities Leadership Council, and brownfields coordinators regarding EPA initiatives to promote innovative technology in waste management programs. EPA, Washington, D.C. April 29. Letter. MacDonald, J.A. 1994. Germ warfare. Garbage: The Independent Environmental Quarterly (Fall):52–57. MacDonald, J.A., and M.C. Kavanaugh. 1994. Restoring contaminated groundwater: An achievable goal? Environmental Science & Technology 28(8):362A-368A. MacDonald, J.A., and M.C. Kavanaugh. 1995. Superfund: The cleanup standard debate. Water Environment & Technology 7(2):55–61. MacDonald, J.A., and B.E. Rittmann. 1993. Performance standards for in situ bioremediation. Environmental Science & Technology 27(10): 1974–1979. Mercer, J.W., D.C. Skipp, and D. Giffin. 1990. Basics of Pump-and-Treat Ground-Water Remediation Technology. EPA/600/8-90/003. Ada, Okla.: EPA. National Commission on Superfund. 1994. Final Consensus Report. Keystone, Colo.: The Keystone Center. NRC. 1993. In Situ Bioremediation: When Does It Work? Washington, D.C.: National Academy Press. NRC. 1994. Alternatives for Ground Water Cleanup. Washington, D.C.: National Academy Press.
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Innovations in Ground Water and Soil Cleanup: From Concept to Commercialization OTA (Office of Technology Assessment). 1989. Coming Clean: Superfund Problems Can Be Solved. PB90-142209. Springfield, Va.: National Technical Information Service. OTA. 1995. State of the States on Brownfields: Programs for Cleanup and Reuse of Contaminated Sites. Springfield, Va.: National Technical Information Service. Reichard, E., C. Cranor, R. Raucher, and G. Zapponi. 1990. Groundwater Contamination Risk Assessment: A Guide to Understanding and Managing Uncertainties. Washington, D.C.: International Association of Hydrological Sciences. Russell, M., E.W. Colglazier, and M.R. English. 1991. Hazardous Waste Remediation: The Task Ahead. Knoxville: University of Tennessee, Waste Management Research and Education Institute. Spitz, K., and J. Moreno. 1996. A Practical Guide to Groundwater and Solute Transport Modeling. New York: John Wiley & Sons. Tremblay, D., D. Tulis, P. Kostecki, and K. Ewald. 1995. Innovation skyrockets at 50,000 LUST sites. Soil and Groundwater Cleanup 1995 (Dec.):6–13.
Representative terms from entire chapter: