1
Introduction

The last 30 years have seen a rise in the nation’s awareness of hazardous materials and how their discharge and ultimate disposal can affect public health and the environment. Approximately 217,000 contaminated sites that have as much as 31 million cubic yards of soil, 1.2 billion cubic yards of sediment, and 1.4 million acres of groundwater plumes require remediation to prevent adverse effects on public health and the environment from past military, industrial, agricultural, and commercial operations (EPA, 1997, 1998a). These sites range from those contaminated by relatively simple petroleum hydrocarbon spills to complex multicontaminant sites, of which there may be hundreds at federal facilities such as military bases. Table 1-1 lists the major classes of contaminants found at hazardous waste sites in the United States. The cost to clean up these 217,000 sites is estimated in EPA (1997) to be at least $187 billion, while the National Research Council’s best guess of the present value cost is $280 billion using current cleanup policies, with a range from $140 billion if cleanup policies are less stringent to $630 billion if cleanup policy becomes more stringent (NRC, 1994)1.

1  

Probst and Konisky (2001) provided unit cost estimates from actual Superfund expenditures, but did not produce a nationwide cleanup cost estimate that is comparable to either NRC (1994) or (EPA) 1997. Comparisons with other sources of information indicate the NRC values provide a reasonable estimate of the order of magnitude of cleanup costs likely over the next 30 years. OMB estimated the cost to cleanup property owned by the federal government of $234–389 billion over the next 75 years (Federal Facilities Policy Group, 1995). None of these cost estimates include munitions, chemical weapons, or other non-hazardous waste problems. No studies were found that specifically addressed the impact of the greater use of containment and institutional controls.



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1 Introduction The last 30 years have seen a rise in the nation’s awareness of hazardous materials and how their discharge and ultimate disposal can affect public health and the environment. Approximately 217,000 contaminated sites that have as much as 31 million cubic yards of soil, 1.2 billion cubic yards of sediment, and 1.4 million acres of groundwater plumes require remediation to prevent adverse effects on public health and the environment from past military, industrial, agricultural, and commercial operations (EPA, 1997, 1998a). These sites range from those contaminated by relatively simple petroleum hydrocarbon spills to complex multicontaminant sites, of which there may be hundreds at federal facilities such as military bases. Table 1-1 lists the major classes of contaminants found at hazardous waste sites in the United States. The cost to clean up these 217,000 sites is estimated in EPA (1997) to be at least $187 billion, while the National Research Council’s best guess of the present value cost is $280 billion using current cleanup policies, with a range from $140 billion if cleanup policies are less stringent to $630 billion if cleanup policy becomes more stringent (NRC, 1994)1. 1   Probst and Konisky (2001) provided unit cost estimates from actual Superfund expenditures, but did not produce a nationwide cleanup cost estimate that is comparable to either NRC (1994) or (EPA) 1997. Comparisons with other sources of information indicate the NRC values provide a reasonable estimate of the order of magnitude of cleanup costs likely over the next 30 years. OMB estimated the cost to cleanup property owned by the federal government of $234–389 billion over the next 75 years (Federal Facilities Policy Group, 1995). None of these cost estimates include munitions, chemical weapons, or other non-hazardous waste problems. No studies were found that specifically addressed the impact of the greater use of containment and institutional controls.

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TABLE 1-1 Types of Contaminants Found at Hazardous Waste Sites Contaminant Category Example Constituents Nonhalogenated volatile organic compounds (VOCs) BTEX (benzene, toluene, ethylbenzene, xylene) Acetone Methyl ethyl ketone Methyl tert butyl ether (MTBE) Halogenated VOCs Tetrachloroethylene Trichloroethylene Cis-1,2-dichloroethylene Vinyl chloride;1,1,1-trichloroethane 1,1-Dichloroethane Nonhalogenated semivolatile organic compounds (SVOCs) Phthalates such as n-bis(2-ethylhexyl)phthalate 2-Nitroaniline Benzoic acid Polynuclear aromatic hydrocarbons (PAHs) such as naphthalene, anthracene, benzo(a)pyrene Non-halogenated pesticides/herbicides such as parathion Halogenated SVOCs Polychlorinated biphenyls (PCBs) Dioxins/furans Halogenated pesticides/herbicides such as 4,4’-DDD and 4,4’-DDT Fuels Gasoline range hydrocarbons Diesel range hydrocarbons Residual range hydrocarbons Inorganics Heavy metals such as lead, zinc, mercury, copper, cadmium, beryllium Nonmetallic elements such as arsenic Asbestos Inorganic cyanides Perchlorate Radionuclides Radium-224, -226 Cesium-134, -137 Explosives/propellants Trinitrobenzenes (TNB) 2,4-Dinitrotoluene (2,4-DNT) 2,4,6-Trinitrotoluene (TNT) Nitrocellulose Hexhydro-1,3,5-trinitro-1,3,5-triazine (RDX) Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraocine (HMX) Unexploded ordnance NA   SOURCE: Adapted from FRTR (1998).

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Growing public awareness of hazardous waste issues was triggered by key incidents in the 1970s at locations such as Love Canal, New York, and Times Beach, Missouri. In response to public concerns, two important environmental statutes were written into law: the Resource Conservation and Recovery Act (RCRA) of 1976 (42 USC 6901) and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980 (42 USC 9601). CERCLA (also known as Superfund) and RCRA mandate the identification of hazardous waste sites, their assessment for contamination and risk to humans and ecological receptors, and the process by which they should be remediated. The Superfund Amendments and Reauthorization Act (SARA) of 1986 brought all military facilities under the authority of the Superfund program. These laws and corresponding state statutes have instigated a massive effort to clean up thousands of hazardous waste sites across the country. In general, most of the sites that have been successfully cleaned up to “background” levels were relatively simple, with well-defined contamination or releases of predominantly degradable petroleum hydrocarbons to a subsurface area characterized by relatively homogeneous hydrogeology (NRC, 1994). Sites contaminated with more recalcitrant contaminants or with more complex hydrogeologic features have proved to be a significant challenge on every level—technological, financial, legal, and sociopolitical. Figure 1-1 shows the steps in the CERCLA process—the cleanup paradigm used at the most complex hazardous waste sites, particularly those located on federal facilities (see NRC, 1999a, for a detailed description of CERCLA). The first half of the CERCLA process involves site characterization and risk assessment; the second half includes a variety of risk management activities, including selection and implementation of a remedy. The Department of Defense (DoD) and other federal (e.g., RCRA) and some state cleanup programs have developed their own terminology for individual steps in the cleanup process, although all include investigation, remedy evaluation and selection, the site-specific remedy design and construction, and ongoing remedy operation. This report predominately uses DoD and CERCLA terminology, and the reader is referred to each program for other nomenclature. As shown in Figure 1-2, the latter stages of site cleanup at military facilities are characterized by milestones such as remedy in place, response complete, and site closeout. Given the time that has passed between the signing of RCRA and CERCLA and the present, a large percentage of identified hazardous waste sites have reached the latter stages of cleanup—that is, after selec-

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FIGURE 1-1 The steps of the CERCLA process. Each box describes the actions taken during the sequential phases. SOURCE: Adapted from EPA (1992).

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FIGURE 1-2 Milestones of the Defense Environmental Restoration Program. SOURCE: Office of the Deputy Under Secretary of Defense (1998). tion of the remedy (as codified in a Record of Decision). For example, as of September 2000, 82 percent of the 1,509 sites on the National Priorities List (NPL), which lists many of the nation’s most contaminated areas, had moved beyond remedy selection to remedy design, remedy construction, and construction completion (www.epa.gov/superfund/).2 Only 3 percent of sites had not yet begun the remedial investigation process. Fourteen percent of the sites had studies underway or a remedy selected. Several National Research Council (NRC) reports have addressed the cleanup of hazardous waste sites, primarily with an emphasis on contaminated soil and groundwater but more recently on contaminated sediment (NRC, 1993, 1994, 1997, 1999a,b, 2000, 2001). These reports have largely focused on risk assessment and treatment strategies applicable to the earlier phases of CERCLA or similar cleanup paradigms. At the request of the U.S. Navy—a responsible party with a large liability in 2   Individual sites are evaluated based on the degree of hazard presented using the Hazard Ranking System. If a site receives a high enough score, usually the entire facility is placed on the NPL, even though there may be many other sites at the facility that do not pose as great a hazard. It should be noted that EPA defines site as the “entire facility, installation, unit”, whereas DOD defines “site” as a discrete area of contamination on an installation or facility.

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hazardous waste sites—this report specifically addresses the latter stages of site cleanup. In particular, it evaluates the unique technological and regulatory problems present at those sites for which chosen remedies have been in place but for which cleanup goals have not (for a number of reasons) been met. A comprehensive and flexible approach, known as adaptive site management, is proposed as a mechanism for dealing with such difficult sites over the long term. The hazardous waste challenges facing the Navy are similar in nature to those facing many potentially responsible parties (PRPs) in the United States, with some important distinctions as mentioned below. As of September 30, 2001, the Navy identified 3,656 contaminated sites at active facilities and 1,020 sites at BRAC (Base Realignment and Closure) facilities (Navy, 2002). The majority of Navy sites are in the latter stages of cleanup; in fact, the number of sites that have reached “response complete” is 2,797—about 60 percent of all sites identified. Table 1-2 lists the number of Navy contaminated sites that are presently at each stage of the cleanup process. The Navy estimates that the remaining cumulative cost to complete remediation in today’s dollars is $4.77 billion (Navy, 2002). [Since its inception in 1986, $3.81 billion has been spent in the Navy’s Environmental Restoration Program (Navy, 2002.)] CHARACTERISTICS OF NAVY FACILITIES The goals of the Navy’s Environmental Restoration Program are many, including to (Navy, 2002): Comply fully with federal, state, and local requirements; Act immediately to eliminate human exposure to contamination that poses an imminent threat, including removing or containing the contamination; Across the nation, first clean up sites posing the greatest risk to human health and the environment; Develop partnerships with the U.S. Environmental Protection Agency (EPA), state, and local regulatory agencies; Involve the local community through Restoration Advisory Boards. Encourage participation with timely information and opportunities for public comment, and take all comments into account when making decisions;

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TABLE 1-2 Number of Navy Contaminated Groundwater, Soil, and Sediment Sites by Phase of Cleanup as of late 2001 Phasea Groundwaterb Soilc Sedimentc Soil/ Sedimentd Preliminary Assessment/ Site Inspection 93 439 22 447 Remedial Investigation/ Feasibility Study 467 834 226 908 Remedial Design 211 113 33 118 Remedial Action– Construction 234 110 24 114 Remedial Action– Operation 317 115 44 129 Response Complete 737 988 163 1,058 Long-Term Monitoring 259 63 28 68 Totale 1,894     2,842 SOURCE: NORM database, which is an internal database of contamination problems at Navy installations. aSee Figures 1-1 and 1-2 for descriptions of the phases. bColumn entries do not equal total because a site may be in multiple phases and thus counted more than once. cA site may have both contaminated soil and sediment and would be counted on both lists. Thus, the soil/sediment column is not a total of the previous two columns. dUnlike in groundwater column, sites with overlapping or multiple phases are classified under the earliest phase. Thus, the entries do equal the total. eThe total from this table (4,736) is larger than the number of Navy sites quoted in the main text (4,676) because some sites have both contaminated groundwater and soil/sediment and are counted twice in Table 1-2. Expedite the cleanup process and demonstrate a commitment to action; and Consider current, planned, and future land use when developing cleanup strategies. Two major factors differentiate the Navy’s Environmental Restoration Program from typical contaminated sites. The first is the wide array of contaminants reflecting the military’s multiple purposes over the last 100 years. Some private industrial sites that have operated for decades may have released a vast array of contaminants, especially if the industrial owner and products have changed over time. However, the sheer number and diversity of Navy facilities and activities have led to a greater array of complex contaminants than any one industrial owner

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typically faces. Second, Navy facilities encompass a diversity of locations, including a high prevalence in coastal environments. Although other branches of the military and the Department of Energy have a comparable diversity and number of contaminant types and facility locations, the higher prevalence of Navy facilities along major coastal or inland waterways brings sediment contamination to the forefront as an important issue for the Navy. A hypothetical, yet “typical,” Navy facility is shown in Figure 1-3 to illustrate the diversity of challenges present at these facilities. Navy facilities are contaminated by an array of compounds that reflect a variety of activities. Most Navy facilities provide services, materials, and equipment to support aircraft, submarines, and ships. Large-scale transportation and industrial activities associated with this mission have resulted in contamination by marine and aviation fuel, solvents, and heavy metals. Chlorinated solvents have been widely used for equipment cleaning and degreasing. At some facilities, large-scale industrial activities such as designing and manufacturing weapons systems have introduced explosives, fuels, chlorinated solvents, and metals. Painting activities release heavy metals and solvents, and the discharge or spill of bilge water results in oil contamination. Site types associated with these activities include industrial landfills, waste disposal pits, above-ground and underground storage tanks, and spill sites. Groundwater and soil contaminant sources also include those associated with urban centers, such as municipal solid waste landfills, wastewater treatment plants, hospitals, laundries, golf courses, and underground storage tanks for automobile and truck fuels. Other potential sources of contamination include personnel training activities, such as “fire pits” where fire-fighting techniques have been practiced. Of those listed in Table 1-1, certain contaminants either because of their sheer volume or their recalcitrance are more prevalent at hazardous waste sites both across the United States and at Navy facilities. Table 1-3 lists the top ten organic and inorganic compounds on the 1999 CERCLA Priority Hazardous Substances for the nation’s most contaminated sites, which is based on frequency of occurrence, toxicity, and potential for human exposure. Arsenic and lead are the inorganic compounds of greatest concern, while vinyl chloride, benzene, and polychlorinated biphenyls are the most problematic organic compounds. Determining whether these contaminants are present at Navy sites is hampered by the lack of a central, comprehensive compilation of data on Navy hazardous waste sites (although contaminant mass and concentration data for individual sites are collected at each facility). NRC (1999a)

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FIGURE 1-3 Typical Navy facility. SOURCE: Courtesy of the U.S. Navy, Marine Environmental Support Office.

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TABLE 1-3 Top Ten Inorganic and Organic Contaminants on the 2001 CERCLA List of Priority Hazardous Substances (rank number is out of 275) Inorganic Constituent Rank Organic Constituent Rank Arsenic 1 Vinyl chloride 4 Lead 2 Polychlorinated biphenyls 5 Mercury 3 Benzene 6 Cadmium 7 Benzo[a]pyrene 8 Chromium, hexavalent 18 Polycyclic Aromatic Hydrocarbons (PAHs) 9 Benzo[b]fluoranthene 10 Beryllium 38 Chromium 11 Cobalt 49 1,1,1-Tricholoro-2,2-bis(p-chlorophenyl) ethane (DDT) 12 Nickel 53 Zinc 73 Aroclor 1254 (PCB) 13 Chloroform 76 Aroclor 1260 (PCB) 14   SOURCE: ATSDR (2002). Note that TCE is ranked 15, dibenzo(A,H)anthracene is 16, dieldrin is 17, chlordane is 19, and hexachlorobutadiene is 20. indicates that organic contaminants are the most common contaminants found at Navy facilities. Petroleum, oil, and lubricants and hydrophobic organic contaminants exist at over half of all facilities, and pesticides are found at almost a quarter. Metals are found at over 42 percent of Navy facilities. It was not possible to determine from readily available data whether the reported contaminants exist as mixtures at a given site. Subsequent to the NRC (1999a) evaluation, the Navy was asked to provide more detailed information about the contaminants found at its facilities and at individual sites. Surprisingly (given the 1999 evaluation), the NORM database (a database internal to the Navy which contains information on contamination at Navy installations) revealed that metals are the most frequently encountered contaminant type for all site types (groundwater, soil, and sediment). Lead, zinc, and barium are among the top five frequently encountered constituents at both groundwater and soil sites, with lead being the most common contaminant at all site types. Nonhalogenated volatile organic compounds (VOCs) are the second most frequent contaminant type at groundwater sites on Navy facilities, with benzene and toluene being the most frequently encountered constituent in this category. Benzo[a]pyrene and pyrene are the most frequently encountered organic compounds at soil and sediment sites, respectively. It is not clear how accurately these data reflect conditions at Navy facilities. If metals are the most prevalent contaminants at Navy sites, then remedial actions will need to be designed to better address this fact.

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Although there are apparent similarities between the NORM database data and the data in Table 1-3, the data from the NORM database provided to the committee indicated prevalence only, whereas Table 1-3 also considers factors such as toxicity and mobility. If it has not already been accomplished, the Navy should consolidate its contaminant information into a single database, determine relative risk for all of its contaminated sites,3 and then identify appropriate response strategies for those contaminants and sites posing the highest risks. The Navy identified four scenarios as characteristic of their contaminated sites: petroleum hydrocarbons in soils and groundwater, chlorinated solvents in groundwater, metals in soils and groundwater, and persistent contaminants in sediment. These scenarios are generally consistent with the most frequently occurring contaminants at Navy facilities (see Table 1-1 in NRC, 1999a). The chemical properties and the fate-and-transport mechanisms for these four contamination scenarios are discussed below to provide background on their ease of remediation and the innovative technologies that are discussed later. Unexploded ordinance, radioactivity, and other less prevalent compounds are not considered further in this report. Figure 1-4 shows the universe of pathways of human exposure to hazardous waste. At any given site, some pathways will predominate over others and control both the risk assessment and the remedial goal chosen. Ecological receptors are the primary driver for risk assessment at many hazardous waste sites, particularly where contaminated sediment is involved. Petroleum Hydrocarbons in Soil and Groundwater Although generally not considered high-risk or difficult to remediate, sites contaminated with petroleum hydrocarbons remain a concern because of their sheer number. Petroleum hydrocarbons include compoonents of gasoline [benzene, toluene, ethylbenzene, and xylene (BTEX) and oxygenates such as MTBE] as well as other fuels. When free-phase hydrocarbons are released to soil, they are retained on soil pores until sufficient hydrocarbon has spilled to saturate the soil. Once the soil is saturated, such nonaqueous phase liquids (NAPLs) typically accumulate 3   This could be accomplished, for example, using the qualitative Relative Risk Site Evaluation Framework developed for the Navy by Anderson and Bowes (1997).

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(Howard and Moore, 1991). Navy facilities also are likely to support important habitats for resting, feeding, and reproduction of various mammalian species, both aquatic (otters, seals, and sea lions) and terrestrial (mice, voles, shrews, and muskrat) in the near-shore and wetland areas. Facilities located in Florida, Hawaii, and Alaska present special and challenging cases. Assessing impacts on coral-dominated ecosystems in Hawaii, Florida, and Puerto Rico may require methods not routinely applied at other contaminated sites. Likewise, in Alaska there are habitats (tundra) and potential receptors (brown bear) that are not found in the lower 48 states. The life-history and other important basic biological data necessary for risk assessment may be missing for some bird species that are found only in the Hawaiian islands, necessitating the collection of these data on rare or highly localized species at particular facilities. In Alaska, the large number of migratory birds residing there during the summer months while raising their offspring must be considered. As with estuarine and marine aquatic species using the estuary for a rearing area, there may be a significant proportion of juvenile migratory birds inhabiting areas subject to contaminant releases from coastal facilities. Although urbanization is dominant outside Navy facilities in many coastal areas, there may be large terrestrial areas within a facility that have not been altered since the facility was occupied originally and may be functioning as habitat refuges. Because of their importance from a national security perspective, many Navy facilities restrict human movement onto the facility and offset the perimeter from residences or commercial entities. These areas may be important for feeding, nesting, and resting for terrestrial species. The same may be true of some of the aquatic environments on the site. More important, some larger facilities may contain remnants of ecosystems that have vanished elsewhere over the last 50–80 years and, as such, may represent unique biological reservoirs worthy of protection. Even if there are no such remnants present, these habitat islands may still provide refuge necessary to the continued existence of some regionally important rare plants and animals. The high prevalence of wetlands at Navy facilities is an additional area of concern because of the importance of freshwater and estuarine wetlands in providing various services, including diverse food webs and nutrient cycling functions, transport and degradation of contaminants, and provision of breeding grounds for important commercial species (NRC, 1995). Estuarine and marine wetlands along the Atlantic, Gulf, and Pacific Coasts have been greatly reduced in area since European settlement (Dahl, 1990), such that their associated habitats and biological

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communities will be in need of careful consideration during hazardous waste management at Navy facilities. TRENDS IN REMEDY SELECTION As the nation’s remediation efforts under CERCLA and RCRA have matured over the last two decades from investigation to implementation, several trends in remedy selection are evident. According to an EPA evaluation of 757 construction completion sites, the most commonly utilized cleanup approaches are (1) excavating hazardous soil and solid waste (352 sites), (2) capping (348 sites), and (3) pumping and treating contaminated groundwater (284 sites) (EPA, 2001a). These statistics reflect the fact that more than one technology can be used at an individual site. Most remedies have been chosen to treat so-called principal threats; thus, from 1982 to 1999 treatment of groundwater was selected at a majority of sites rather than containment or offsite disposal (EPA, 1996, 2001a). In fact, treatment at all or a portion of the source areas at Superfund sites increased from 14 percent to 30 percent in the 1982– 1986 period to a peak of 74 percent in 1993 and then decreased to around 45 percent in 1999 (Figure 1-8a,b). Concomitantly, containment of the source area followed an opposite trend. The use of institutional controls, monitoring, and other remedies (beyond containment and treatment) has increased steadily over the 1982–1999 period, such that institutional controls are now part of the remedy at 368 of 757 construction completion sites (EPA, 2001a). Monitored natural attenuation (MNA) alone or in conjunction with other remedial actions increased from 0 percent in 1982 to between 13 percent and 25 percent in the 1997 to 1999 period (Figure 1-8c). A common reason cited for selecting MNA at contaminated soil and groundwater sites is “low and decreasing concentrations of contaminants at the site.” Innovative technologies, defined by EPA as those technologies or applications of technologies that have had limited full-scale application, have been selected in only 19 percent of the cases in which treatment is involved (EPA, 2001b). The rate of selection of innovative treatment technologies has decreased consistent with the overall trend in the selection of treatment technologies. Partly for this reason, there is effectively little traditional economic incentive for the small business entrepreneurial research sector to develop innovative cleanup technology (NRC, 1997). As a result, research on innovative treatment technologies

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is sponsored almost exclusively by federal agencies and, in some circumstances, by individual companies and industry groups that have joined with federal agencies in seeking more cost-effective solutions to common problems. These long-term trends in remedy selection should not be surprising. In the early 1980s, knowledge of the technical capabilities of permanent remedies for contaminated sites was limited. After CERCLA was amended in 1986 giving a preference for permanent remedies and attainment of drinking water standards in groundwater, the number of treatment remedies dramatically increased. The primary treatment technology for contaminated soils, solid waste, and some contaminated sediments was high-temperature incineration, which is the most expensive method of treatment (EPA, 2000b). As a result, the unit cost of hazardous waste cleanups and the estimates of the long-term remediation costs escalated dramatically. By the early 1990s, new knowledge about the limitations of technology became available. NRC (1994) reported that it is not feasible to reduce groundwater concentrations to drinking water standards or health-based cleanup goals with existing technology in a reasonable time frame (decades) at a large number of contaminated sites. Similarly, the DoD Inspector General concluded that 78 pump-and-treat systems operated as of 1996 remediate contamination slowly, cost $40 million annually, and will not attain cleanup goals within a reasonable period of time4 (DoD, 1998). The report noted that as of 1998, these pump-and-treat systems “continued to operate without any form of review to determine their efficiency and effectiveness.” The cumulative long-term cost of these systems was estimated to be as much as $2.3 billion in the year 2020 assuming 97 systems. As discussed in Chapter 5, optimizing the operation of these pump-and-treat systems will be critically important to the success of remediation at many facilities, including Navy sites. In response to the rising costs of contaminated-site cleanups and the growing recognition of the limitations of technology, federal and state regulatory agencies issued a number of explicit policies that led to the acceptance of more containment, as reflected in the trends discussed above. EPA’s 1990 Superfund remedy rules state that even though permanent remedies are preferred, EPA expects to use treatment to address the principal threats posed by a site, wherever “practicable,” and engi- 4   The determination of a reasonable period of time varies both within and between federal and state agencies. It has been previously noted to be 30 years (EPA, 1988) and 70 years (EPA, 1989) but no exact determination exists.

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FIGURE 1-8 Trends in remedy selection, 1982 to 1999. (A) Number of RODs signed. (B) Percentage of different types of RODs. (C) Percentage of RODs with monitored natural attenuation as the remedy. SOURCE: EPA (2001b). neering controls, such as containment, for sites that pose a relatively low long-term threat (EPA, 1991). Indeed, EPA’s polychlorinated biphenyl (PCB) disposal rule allows soil contaminated with low levels of PCBs and other wastes to remain at a site as long as human health and the environment are protected from an unreasonable risk (EPA, 1998b). The increased use of containment and monitored natural attenuation is likely to continue and will have several important implications. Because these remedies result in contamination remaining onsite, continual monitoring including the five-year review process will be required. Indeed, a recent report (NRC, 2000) highlights the complexity of assessing the performance of natural attenuation and emphasizes the need for long-term monitoring. In addition, groundwater remedial actions and monitoring activities at CERCLA, RCRA corrective action, and non-state sites cannot legally be terminated unless the chemicals remaining at the site are no longer a significant threat to human health or the environment.

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At the vast majority of containment sites where the groundwater cleanup goal remains a drinking-water maximum contaminant level (MCL), cleanup times will extend from a few years to thousands of years, with the actual treatment time highly uncertain (NRC, 1994). Reducing the time required for remedy operation and monitoring is the motivation for developing innovative technologies, many of which are expected to focus on source removal. STATEMENT OF TASK AND REPORT ROADMAP Although 2,797 out of 4,676 Navy sites have achieved “response complete” (Navy, 2002), these sites consist mainly of petroleum hydrocarbon contamination and other problems that are relatively easy to address. These numbers may even include sites that were found, on closer inspection, to not be contaminated. Thus, the bulk of the difficult sites remain to be completely remediated. This is reflected in the Navy’s cleanup budget, which is disproportionately allocated to the most contaminated sites. According to data provided by the Navy in 1998, the 59 percent of sites that ranked as high risk5 comprised 81 percent of total cleanup costs, while low risk sites comprised 25 percent of the ranked sites but only 8 percent of the cost. As the Navy plans for completion of the Environmental Restoration Program, several issues have become evident. First, the average time for completion of a cleanup remedy at Superfund sites (once a site has been placed on the NPL) is 10.6 years (GAO, 1998). Despite the fact that environmental remediation at Navy facilities has proceeded for a short period of time compared to the decades of military operations that are the source of present-day contamination, there is pressure to reduce the time needed to restore these sites, particularly when property is slated for transfer of ownership under BRAC. Second, conventional remediation technologies, such as pump-and-treat for groundwater cleanup, have been shown to be inadequate in meeting drinking-water-level cleanup standards for many of the complex sites typical of Navy facilities (NRC, 1994). Finally, decision making during the latter part of cleanup is unstructured, partly because the number of complex sites reaching this stage has been relatively low. For example, it is not clear how to change or terminate remedies that have proved to be ineffective or how to change cleanup goals. 5   According to the Relative Risk Site Evaluation model.

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To obtain advice in overcoming these obstacles, the Navy requested the NRC to study issues associated with the remediation of contaminated soil, sediment, and groundwater at Navy facilities and provide guidance on risk-based methodologies, innovative technologies, and long-term monitoring. The NRC committee’s first report (NRC, 1999a) reviewed existing risk-based methodologies, described their strengths and weaknesses, and recommended a risk-based decision-making approach for the Navy. As a follow-up activity, the committee was asked to provide guidance on the latter stages of site remediation, including remedy selection, remedy operation, long-term monitoring, and site closeout. In particular, the committee was asked to define a decision-making framework that is embodied within a “systems engineering approach” to site cleanup. It was asked to review innovative technologies for cleanup of groundwater, sediment, and soils, focusing on the top technologies that should be considered for the three or four greatest problems encountered by the Navy. It was also asked to consider how remedies could be altered over time to introduce innovative technologies. This would be applicable in cases where the chosen remedy is no longer optimal because of changing site conditions, the limited efficacy of technologies, or the discovery of new contamination and/or exposure pathways. Finally, the committee was asked to define logical endpoints and milestones for site closure, including determinations of technical impracticability. This report proposes a decision-making approach for site cleanup— adaptive site management (ASM)—that considers the entire lifecycle of a remedial project. The components of ASM include site characterization, risk assessment, selection and implementation of the remedy, monitoring performance of the remedy, adapting the remedy or management goals to accommodate new knowledge and changing conditions in order to improve performance and cost efficiency, long-term stewardship, and site closeout. ASM facilitates making decisions about when remedies can be changed due to ineffectiveness, when to incorporate a new technology, when remedies can be discontinued, and when site cleanup goals should be revised. Chapter 2 introduces the multiobjective nature of cleanup and the ineffectiveness of current remedies, which are problems that can be accommodated by ASM. The specific components of ASM are then described. Chapter 3 discusses the environmental monitoring needed to support adaptive site management and the interpretation of monitoring data. Adaptive site management is characterized by an evaluation and experimentation track that occurs in parallel with remedy operation. This activity is discussed in Chapter 4. Innovative technologies of relevance to Navy sites are the focus of Chapter 5. Finally, Chap-

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ter 6 considers the nontechnical barriers to the use of adaptive site management, such as regulatory constraints, and the roles of public participation and long-term stewardship in adaptive site management. Because there are similarities between the Navy cleanup program and those of other potentially responsible parties, the conclusions and recommendations are applicable to a broad universe of sites, including those at any federal facility. Thus, the report is intended not only for Navy remedial project managers but also for higher level managers and decision makers within the Navy Environmental Restoration Program and their counterparts in other federal agencies and private organizations that have a sizable cleanup liability. REFERENCES Anderson, J. L., and M. D. Bowes (Center for Naval Analysis). 1997. Appendix A: Relative Risk, from Department of the Navy Environmental Cleanup Program: Cost Control. Apitz, S. E.2001. Navigating in uncertain waters: the science, technology and politics of managing contaminated marine sediments. Presentation to National Research Council Committee on Environmental Remediation at Navy Facilities. February 28, 2001. San Diego, CA. Agency for Toxic Substances and Disease Registry (ATSDR). 2002. 2001 CERCLA list of priority hazardous substances. Available at http://www.atsdr.cdc.gov/clist.html. Benner, S. G., J. N. Moore, and E. Smart. 1995. Geochemical processes in a transition zone between surface water and acidic, metal-rich groundwater. Environ. Sci. Technol. 29:1789–1795. Bouwer, E. J. 1992. Bioremediation of organic contaminants in the subsurface. Pp. 287–318 In: Environmental Microbiology. R. Mitchell (ed.). New York: John Wiley. Chapelle, F. H. 1993. Ground-water microbiology and geochemistry. New York: John Wiley & Sons. Cohen, R. M., and J. W. Mercer. 1993. DNAPL site evaluation. Boca Raton, FL: C. K. Smoley. Dahl, T. E.1990. Wetlands losses in the United States: 1780s to 1980s. Washington, DC: U.S. Fish and Wildlife Service. Department of Defense. 1998. Evaluation of DoD waste site groundwater pump-and-treat operations. Report No. 98-090, Project No. 6CB-0057. Washington, DC: Office of the Inspector General. Environmental Protection Agency (EPA). 1988. Guidance for conducting remedial investigations and feasibility studies under CERCLA (interim final). EPA 540/G-89/004. Washington, DC: EPA OSWER.

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