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Alternatives for Ground Water Cleanup 6 Setting Goals For Ground Water Cleanup The preceding chapters provide clear evidence that a range of conditions and complexities exist at waste sites where ground water contamination has occurred. While the conventional and innovative technologies described in this report provide approaches for restoring these sites, there are limits to how completely and how quickly existing technologies can remove contamination from ground water. Historically, the goal of ground water remediation in the United States has been to protect public health and the environment. If the levels of remediation required could be achieved rapidly and at low cost with existing technologies, no conflict would exist between technology's capabilities and society's goals. However, in a number of cases, existing ground water cleanup goals cannot be met with current technologies. In other cases, achieving these goals will require extraordinary amounts of time (decades to centuries) and money (tens of millions of dollars). Thus, a public policy decision must be made about whether the goals of ground water treatment should be changed to reflect what can be achieved today. The Committee on Ground Water Cleanup Alternatives discussed several questions relating to the goals of ground water cleanup. Should existing goals (which are usually drinking water standards) be changed to be consistent with the highest level of treatment technically achievable today? Should the goals be maintained and the objective kept at meeting the goals, irrespective of technologic capability, time needed, and cost?
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Alternatives for Ground Water Cleanup Should the goals be made stricter and more consistent with a nondegradation approach in order to restore ground water quality to its fullest? Should the Environmental Protection Agency (EPA), in setting goals, consider other factors such as cost, fairness to all stakeholders, and comparative risks of exposure to contaminants in ground water relative to involuntary and voluntary risks people take in everyday life? In exploring these questions, the committee defined its role as one of compiling and reviewing information on risks, benefits, costs, and uncertainties that surround the evaluation of these issues, rather than undertaking and contributing original research. The committee's main mission was to consider the degree to which technologies can restore contaminated sites. Nevertheless, technology does not operate in a vacuum: cleanup goals will have a significant impact on the type of remediation technology selected, on the design of the system, and, ultimately, on whether the effort is perceived as a success or a failure. Therefore, any review of the capabilities of ground water cleanup technologies would be incomplete without an assessment of cleanup goals driving the selection of technologies and of factors driving the selection of cleanup goals. This chapter begins with a review of current U.S. goals for ground water cleanup and a discussion of alternative goals suggested by various interest groups. Next, the chapter discusses the public health and ecological risks that currently drive selection of cleanup goals. It then discusses what is known and not known about the costs of various cleanup options. Finally, it summarizes the committee's assessment of whether changes in ground water cleanup goals are warranted to reflect the limits of technology. CURRENT CLEANUP GOALS The two primary federal laws governing ground water cleanup are the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, also known as the Superfund act because of the fund it established to clean up sites) and the Resource Conservation and Recovery Act (RCRA). Most commonly, ground water cleanup goals under CERCLA and RCRA are set at drinking water standards. However, although drinking water standards are the most commonly used cleanup goals, for any one chemical the cleanup goal may vary depending on the state in which the site is located and whether it is a CERCLA or a RCRA site. Table 6-1 shows a sampling of the range of concentrations that have been used as ground water cleanup goals under current policy.
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Alternatives for Ground Water Cleanup Cleanup Goals Under CERCLA Technically, CERCLA governs any site where there is a release or threatened release of a hazardous substance. However, the EPA generally uses it to order cleanup of closed or abandoned waste sites. The goal-setting process for cleaning up ground water at CERCLA sites is detailed in an EPA regulation known as the National Contingency Plan. Central to this plan (and to the statute itself) is that ground water cleanup goals should meet chemical-specific ''applicable or relevant and appropriate requirements'' from other regulations, known as ARARs. Ground water that could be used for drinking must meet federal requirements under the Safe Drinking Water Act (known as maximum contaminant levels, or MCLs; see Table 6-1) or state drinking water standards, whichever are more stringent. In addition to meeting drinking water requirements, ground water that directly discharges to surface water must meet federal requirements under the Clean Water Act or similar state requirements. Furthermore, if states have antidegradation laws that prohibit the contamination of ground water with certain chemicals, these laws also apply (see the third column in Table 6-1). For example, 24 states have established background levels as the goal of ground water remedial actions; for organic chemicals, the background level is usually zero (EPA, 1991a). If no ARAR exists for a particular chemical, the ground water cleanup goal is based on a site-specific risk assessment. In general, cleanup goals based on risk assessments must result in a risk level of 10-4 to 10-6 for carcinogens (Table 6-1 shows a few examples of 10-4 to 10-6 risk levels) and a hazard index of less than 1 for noncarcinogens. A cancer risk of 10-4 indicates a 1-in-10,000 (or 0.01 percent) risk of contracting cancer from chronic exposure to a certain substance, while a cancer risk of 10-6 indicates a 1-in-1 million (or 0.0001 percent) risk. A hazard index of less than 1 indicates that the level of contamination is less than that known to cause harm. (The hazard index is the ratio of the dose received to the dose known to cause health problems.) For any one chemical, different cleanup goals are possible under CERCLA. Cleanup goals may be higher than MCLs if the aquifer is not usable for drinking. The EPA defines such unusable aquifers as those that (1) cannot supply drinking water to a well or spring sufficient for the needs of an average family; (2) are saline (containing 10,000 mg/liter or more of total dissolved solids); or (3) are otherwise contaminated from other sources beyond restoration using reasonable techniques (EPA, 1986, 1990b). Cleanup goals may also exceed MCLs if they are based on protecting a surface water body to which the ground water discharges rather than on protecting the ground water. Cleanup goals may be lower than MCLs for individual contaminants if multiple contaminants are present
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Alternatives for Ground Water Cleanup TABLE 6-1 Comparison of Potential Ground Water Cleanup Levels (parts per billion) Contaminants Federal Drinking Water Standards (MCLs)a Representative Range of State Cleanup Standardsb RCRA Proposed Corrective Action Levela Representative Examples of 10-4 to 10-6 Risk Range for Carcinogens or Reference Dose for Noncarcinogensc Arsenic 50 BKG-50 50 0.046-4.6 Benzene 5 BKG-5 — 0.35-35 Benzo[a]pyrene/total polycyclic aromatic hydrocarbons 0.2 BKG-0.2 — 0.011-1.1 Cadmium 5 BKG-5 5 18 Carbon tetrachloride 5 BKG-5 0.3 0.2-20 Chromium VI 100 BKG-100 100 180 DDT — BKG-0.1 0.1 0.23-23 Ethylbenzene 700 BKG-700 4,000 1,300 Mercury 2 BKG-2 2 11 Methyl ethyl ketone — BKG-460 2,000 1,800 Pentachlorophenol 1 BKG-1 1,000 0.66-66 Phenol — BKG-6,000 20,000 22,000 Polychlorinated biphenyls 0.5 BKG-0.5 0.5 0.01-1 Tetrachloroethylene 5 BKG-5 0.7 1.3-130 1,1,1-Trichloroethane 200 BKG-200 3,000 1,300 Trichloroethylene 5 BKG-5 5 1.9-190 Vinyl chloride 2 BKG-2 — 0.023-2.3 Xylenes 10,000 BKG-10,000 70,000 12,000
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Alternatives for Ground Water Cleanup a A "—" indicates that no standard has been established for this contaminant. b BKG indicates the natural background level of the contaminant. This column is based on the summary of state cleanup goals in EPA 1991a, which indicates that goals range from background levels to drinking water standards or risk-based concentrations. c The reference dose for noncarcinogens is the dose below which no adverse health effects are expected as reported in Smith, 1993. The risk ranges shown for carcinogens are from Smith, 1993, which regulators in EPA's Region III use as a risk-based screen for Superfund sites to determine whether further investigation is warranted. Smith's data are based on the assumption that a person drinks 1 liter of water per day from ages 1 to 6 years and 2 liters per day from ages 7 to 30 years. SOURCES: Smith, 1993; EPA, 1991a.
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Alternatives for Ground Water Cleanup and the cumulative risk from all of them exceeds 10-4 for carcinogens or a hazard index of 1 for noncarcinogens. Cleanup goals may also be lower than MCLs if the state in which the site is located has state-mandated MCLs or cleanup standards lower than the federal MCLs. As an example, between 1982 and 1991 the EPA selected a cleanup goal of 5 µg/liter (the MCL) for the chemical trichloroethylene (TCE) at 99 Superfund sites, lower concentrations at 23 Superfund sites, and higher concentrations at 13 sites; at 32 sites, the goals were based on risk levels in the 10-4 to 10-6 range.1 Although a range of cleanup goals is possible, as a practical matter federal drinking water standards serve as ceilings for ground water cleanup goals at most sites for the contaminants for which MCLs have been developed. Of the approximately 300 ground water remedial actions selected in the Superfund program between October 1, 1987, and September 30, 1991, the cleanup goal was to achieve drinking water standards through pumping and treating at 270 sites (EPA, 1992). At the remaining sites, the most common alternative to drinking water standards was the provision of alternative water supplies. Cleanup Goals under RCRA RCRA provides for cradle-to-grave management of hazardous wastes. The EPA uses the statute in part to require ground water and soil cleanup at operating hazardous waste treatment, storage, and disposal facilities and at closed facilities that once operated under the RCRA program. The primary EPA regulation for implementing ground water cleanups under RCRA is known as the Corrective Action Rule (EPA, 1990a).2 The Corrective Action Rule has not yet been finalized, but the EPA is nevertheless using it to oversee ongoing work. More than two-thirds of the approximately 100 ground water cleanup remedies under the RCRA corrective action program have been finalized in the past two years (M. Hale, EPA, personal communication, 1994). There is therefore little basis upon which to evaluate the application of cleanup goals under this program. Unlike cleanups governed by CERCLA, cleanups under the RCRA corrective action program have no requirement to meet ARARs from other laws. Nevertheless, the EPA intends that RCRA and CERCLA should establish a consistent approach for ground water cleanup. This internal consistency requirement is a key component of the EPA's long-term ground water strategy (EPA, 1991e). In keeping with the ground water strategy and with the proposed RCRA regulations, the agency anticipates that CERCLA and RCRA will arrive at similar solutions to similar environmental problems and that actions undertaken by one program will be
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Alternatives for Ground Water Cleanup adopted by the other program in cases where the programmatic responsibility for a site shifts from one to the other. Therefore, under RCRA the EPA generally sets cleanup levels at MCLs, even though the proposed corrective action regulations do not require that cleanup goals correspond to ARARs. Exceptions to Goals Based on Drinking Water Standards Although ground water cleanups under CERCLA and RCRA usually require attainment of drinking water standards, the laws have provisions for allowing waivers to these standards even for potential drinking water sources. Both statutes attempt to balance the desirability of meeting health-based cleanup standards wherever possible with the constraints posed by technologic capability and cost. The basis for dealing with these practical considerations differs for the two statutes. Under CERCLA, the EPA may waive health-based cleanup requirements where achieving them is "technically impracticable from an engineering perspective." However, the EPA has been criticized for making minimum use of CERCLA's statutory waiver provisions. Of the 945 sites for which cleanup remedies were selected between 1982 and 1991, only 13 included technical impracticability waivers.3 Because RCRA cleanups need not meet ARARs, the RCRA program is generally more flexible than the CERCLA program in allowing cleanup goals other than MCLs. Under RCRA, those responsible for the cleanup may apply for an "alternate concentration limit" (ACL) in place of drinking water standards as the cleanup goal. The ACL is based on a site-specific risk assessment. The key factor that the EPA considers in granting an ACL is whether it will protect public health at the point of exposure, i.e., whether contaminant concentrations will be reduced to ensure adequate public health protection at the nearest drinking water well. The EPA is increasingly recognizing that attaining drinking water standards is not feasible at certain types of sites and has drafted a guidance document to clarify the policy regarding technical impracticability of ground water cleanup at CERCLA and RCRA sites (EPA, 1993b). The guidance document, discussed in more detail in the next chapter, describes the types of data necessary to demonstrate that the original cleanup goals for a site should be waived because of technical limitations. ALTERNATIVE CLEANUP GOALS Whether the nation's current emphasis on restoring contaminated
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Alternatives for Ground Water Cleanup ground water to drinking water standards is appropriate is a matter of debate. On one hand, achieving MCLs may be impossible at many sites and may be extremely costly even when possible. On the other hand, even when strict cleanup goals are not technically achievable, their existence may provide an incentive against further pollution and may encourage development of cleanup technologies that better protect public health. In the debate over whether strict ground water cleanup goals are appropriate, given the limitations of technology and the high costs, various interest groups have advocated goals ranging from complete restoration to restricting use of the ground water, as shown on Figure 6-1 and explained below. Unrestricted Use Goals At the left end of the spectrum of possible goals in Figure 6-1 is cleanup to allow unrestricted use of the ground water. Many states have identified unrestricted use as the most beneficial use of ground water. Three possible cleanup goals that allow unrestricted use are (1) complete cleanup (i.e., cleanup to concentrations that may sometimes be below natural background levels), (2) cleanup to background levels measurable in uncontaminated areas (or to the detection limit for the contaminant), and (3) cleanup to health-based levels. Complete Cleanup Some groups have advocated complete cleanup—meaning removing the contaminants to zero concentration levels—as a ground water cleanup goal in order to keep the environment "pure" for ethical or moral reasons, to provide the private sector with a continuing incentive to exercise care in handling hazardous wastes, and to ensure that the most thorough cleanup possible occurs. However, the attainment of zero contaminant concentrations as an outcome for ground water remediation should be recognized as an unattainable goal no matter how far cleanup technologies advance in the future. Even pristine waters contain certain inorganic chemicals regarded as contaminants. In addition, it is impossible to prove zero concentrations, given limitations in analytical detection ability. Although the Safe Drinking Water Act established zero as the ultimate goal for carcinogens, the enforceable levels under the act are nonzero MCLs based on the capabilities of drinking water treatment technologies and the detection limits for the contaminants; the nonzero MCLs, rather than the ultimate goal of zero, serve as cleanup goals under Superfund and RCRA.
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Alternatives for Ground Water Cleanup FIGURE 6-1 The range of possible ground water cleanup goals.
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Alternatives for Ground Water Cleanup Cleanup to Background/Detection Limits As a more feasible alternative to zero contaminant levels, some have advocated the use of background concentrations or analytical detection limits as ground water cleanup goals. For example, 24 states use detection limits or background levels as the only acceptable cleanup goal (EPA, 1991a). Cleanup to background levels may be selected in cases where there is a naturally occurring background concentration of a contaminant; otherwise, analytical detection limits serve as cleanup goals. One benefit of using detection limits or background levels as cleanup goals is the elimination of the need for government agencies to define explicitly an "acceptable" risk level. Rather, using detection limits or background levels implies that cleanup is accomplished to the fullest extent measurable with today's technologies. A drawback is the high cost that can be associated with such cleanups; it is possible that such goals will achieve only a small additional benefit—at substantially higher cost—compared with cleanup to specific health-based goals. Another drawback is that detection limits change over time as analytical capabilities improve, meaning that cleanup standards will become outdated as technology advances. Cleanup to Health-Based Levels As discussed above, cleanup to health-based standards is the most common type of goal used today. There are two possible mechanisms for setting health-based goals: (1) using predetermined standards, such as drinking water standards and the other ARARs used at Superfund sites, and (2) using risk assessments at each site. The advantages of using predetermined standards versus using site-specific risk assessments include speed and ease of implementation, consistency in the treatment of similar sites, usefulness for initial screening of contamination to determine its significance, elimination of incentives for industry to locate in the most environmentally lenient states, and avoidance of a need for technical expertise on the part of regulators in order to address toxicological and risk assessment issues on a case-by-case basis (Siegrist, 1989). The use of predetermined standards, if established based on "worst-case" assumptions, will also ensure adequate margins of safety for all sites. However, using predetermined standards also has important drawbacks. The most significant drawback is the inability to account for site-specific exposure patterns, which may result in higher expenditures than are necessary to protect public health at a particular site. In lieu of using previously established standards as health-based
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Alternatives for Ground Water Cleanup goals, formal risk assessments may be used to develop site-specific goals, as is done in some cases under the Superfund and RCRA corrective action programs. The site-specific approach allows flexibility in considering site conditions. It also ensures that the level of risk, which is based on exposure patterns as well as contaminant levels, will be the same at different sites. (When uniform cleanup standards are used, the level of risk may vary from site to site because of different exposure patterns, even if the contaminant concentrations are the same.) One major disadvantage of this approach is that it is time consuming and costly to implement. The site-specific approach requires that regulatory agencies have a technically trained staff large enough to evaluate individually the risk data for each site. Another major disadvantage is that by changing key exposure assumptions, the results can be easily manipulated. It is important to realize that ground water remediation to assure a "safe" drinking water supply may not result in full restoration, because levels of contaminants may remain at concentrations greater than background levels. Further, contaminant levels designed to protect human health may not protect ecological receptors. Separate risk-based goals may be needed for ecosystem protection. Partially Restricted Use Goals Some who believe that the current ground water cleanup program is too costly have advocated using partially restricted use goals, shown in the middle of Figure 6-1. Under this scenario, cleanup goals would correspond to the expected use of the water. In some cases such goals are already used, such as when the goals are based on protecting a surface water body used for boating and fishing but not for drinking. Like health-based goals, partially restricted use goals can be based on predetermined standards, such as water quality criteria, or on site-specific risk assessments. The major drawback of such goals is that they may require institutional controls, such as well restrictions or fish advisories, to prevent excessive human exposure to the contamination. Some have expressed concern about whether it is possible to design policies and institutions capable of perpetually limiting people's use of contaminated water. Technology-Based Goals Many major environmental statutes applicable to media other than ground water use a technology-based approach to setting cleanup goals. For example, under the Clean Water Act municipal wastewater treatment plants are required to treat their effluent to a level achievable by what are known as "secondary treatment" systems (unless more strin-
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Alternatives for Ground Water Cleanup TABLE 6-6 Comparison of Costs for a Conventional Pump-and-Treat System and an In Situ Bioremediation System for Benzene Removal Present Worth Removal Efficiency In Situ Bioremediation Conventional Pump-and-Treat 90 $2,460,000 $3,200,000 99 $3,000,000 $5,020,000 NOTE: The assumptions for the conventional pump-and-treat system in this example are the same as those used in Table 6-5 except that the contaminant is benzene, for which the required effluent concentration is 1 µg/ liter and the retardation factor is 3.6. The hypothetical bioremediation system pumps at 190 liters per minute to supply oxygen and nutrients to stimulate biodegradation. costs, Figure 6-3 shows the cost of cleaning up the TCE plume in the hypothetical example as a function of the tendency of soils at the site to sorb the TCE. In the figure, sorptive capacity is indicated by the retardation factor—the ratio of the total contaminant mass in the aquifer to the contaminant mass dissolved in the ground water. The greater the tendency of the contaminant to sorb (indicated by large retardation factors), the higher will be the cleanup costs, as illustrated by the figure. The cost difference between requiring 90 percent contaminant removal and requiring 99.9 percent removal ranges from approximately $1 million to more than $2 million, depending on the retardation factor. As an illustration of how the cleanup technology chosen affects cleanup cost, Table 6-6 compares costs for a conventional pump-and-treat system and an in situ bioremediation system for benzene removal. As shown in the table, for 90 percent benzene removal, in situ bioremediation provides a substantial savings compared to the conventional pump-and-treat system. Increasing the percent removal to 99 percent, if this were achievable, would provide an even greater cost advantage for in situ bioremediation. (It is important to note that if the in situ bioremediation system cannot reach the required cleanup goal in the predicted time, its life cycle costs may increase to the point where the costs are similar to those associated with conventional pump-and-treat systems.) These hypothetical computations show that changing ground water cleanup goals from 80 or 90 percent contaminant removal to nearly 100 percent contaminant removal can have a substantial effect on cleanup costs at the site level. However, the magnitude of the effect is influenced by local economic conditions, site hydrogeology, and the cleanup tech-
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Alternatives for Ground Water Cleanup nology chosen. Furthermore, it may be partially offset by the need to build and maintain containment systems when a significant quantity of contamination remains in place. Benefits of Ground Water Cleanup In considering costs for ground water cleanup under various scenarios, one must recognize that spending on cleanup yields benefits that have economic value. Benefits include reduced health risks, increased property values for uncontaminated land, and the knowledge that the ground water will be available for unrestricted use in the future. No studies have attempted to compare differences in the dollar value of benefits received for different national ground water cleanup goals. Further, at the time this report was prepared only one study assessing the total national economic benefits of restoring ground water was available, and this study was controversial. The study was carried out for the EPA by McClelland et al. (1992) at the University of Colorado as part of an effort to assess the economic impact of the proposed RCRA regulations.7 The study was controversial because it used an economic analysis method known as contingent valuation to estimate the benefits of clean ground water, and it was criticized by the EPA's Science Advisory Board (1993). Contingent valuation is a method used to estimate what are known as the nonuse values of ground water. Nonuse values are those that individuals place on water unrelated to their own need to use it in the present or the future—values such as desiring to preserve the resource for future generations and desiring to preserve it because it is a unique natural asset. In contrast, use values are those that individuals place on the water to use it today or to have the option of using it for themselves in the future. While most use values can be approximated based on current water prices, nonuse values cannot be determined from observation of actual marketplace transactions. Consequently, economists devised the contingent valuation method to assign monetary worth to non-use values for natural resources. The method estimates nonmarket values by conducting surveys to ask individuals what they are willing to pay to maintain the resource (or what compensation they are willing to accept for its loss). In the EPA study, researchers surveyed a national sample of 900 people and asked, "What would a complete cleanup program be worth to your household, if you faced the hypothetical problem of 40 percent of your water supply coming from contaminated ground water as we have described?"8 The contingent valuation technique is controversial in part because of its short scientific life span and because flaws in the method are still being worked out. The first contingent valuation study of nonmarket
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Alternatives for Ground Water Cleanup goods was completed by Robert K. Davis in the early 1960s (Davis, 1963). During the early 1970s, economists studied the method intensively for valuing atmospheric visibility in the Four Comers region of the southwest, but little research was carried out on its use for valuing other resources (Randall et al., 1975; Rowe et al., 1980). The studies of the 1970s showed that different contingent valuation studies with different designs yielded similar results, leading researchers to believe that the technique might be a useful approach for valuing nonmarket commodities in general (Rowe et al., 1980). However, the research also revealed distinct flaws in the method, including the following: Results may vary depending on experimental design factors, such as whether individuals are surveyed over the telephone or in person and the amount and type of information the researcher provides to the individual (Rowe et al., 1980). The fact that individuals are not actually required to pay their bid may affect the result of the study, although where there are well-defined related markets the magnitude of this bias seems small (Brookshire and Coursey, 1987). Individuals may offer the same bid for cleaning up one hazardous waste site, all related hazardous waste sites, or all hazardous waste sites in a region (Kahneman and Knetsch, 1992), although some researchers have suggested that this problem can be overcome if the contingent valuation analysis is done correctly (Smith, 1992). Despite these and other flaws, many economists believe the contingent valuation method shows promise. For example, Mitchell and Carson (1989) have said that the contingent valuation method may be "a powerful and versatile tool" for measuring the economic benefits of the provision of nonmarketed goods. More importantly, a recent panel convened by the National Oceanic and Atmospheric Administration and chaired by two Nobel Prize-winning economists concluded that the method may be used as a starting point for legal evaluation of nonuse values, as long as sufficient and elaborate scientific safeguards are taken (Arrow et al., 1993). However, other economists caution that the method has not reached a stage of scientific maturity sufficient to place confidence in the reliability and accuracy of the estimates it provides. In a recent general review, Cummings and Harrison (1992) concluded that "the present state of the art of the CVM [contingent valuation method] leads us to what we believe is an unavoidable conclusion: for uses that require that the term 'value' will imply some nexus with real economic commitments of people, it has yet to be demonstrated that the CVM as currently applied is up to the task." A National Research Council committee is currently review-
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Alternatives for Ground Water Cleanup TABLE 6-7 National Benefits of Ground Water Cleanup of U.S. dollars) Present Value of National Benefits of Ground Water Cleanup (billions of U.S. dollars) Discount Rate (real rate, percent) 10-year Time Horizon Indefinite Time Horizon 2 76 420 4 69 210 6 63 140 8 57 110 10 52 85 NOTE: If the amount paid per year were assumed to continue indefinitely rather than stopping in 10 years, the present value of benefits would equal the amount in the second column. There is some evidence that respondents cannot differentiate between a 10-year payoff and an indefinite payoff date. This illustrates how sensitive contingent valuation measures are to exact specifications of the commodity. SOURCE: McClelland et al., 1992. ing this method to determine whether it is appropriate for assessing the future value of ground water. In the EPA study of the national benefits of ground water cleanup, the 900 survey respondents indicated that, on average, they would be willing to add $7.08 to their monthly water bills for the next 10 years to clean up ground water.9 With approximately 100 million households in the United States, this estimate indicates an aggregate willingness to pay $8 billion per year for 10 years. Table 6-7 shows the present value of this annual willingness to pay using various discount rates for a 10-year period. Because there is some evidence that respondents cannot differentiate between a 10-year payoff date and an indefinite payoff date, also shown in Table 6-7 are present worth values assuming that people are willing to pay the $7.08 indefinitely. As shown in Table 6-7, based on the EPA study the benefits of ground water cleanup, like the costs, may range up to hundreds of billions of dollars. Because of questions about the validity of the EPA study, one must view Table 6-7 with caution. The Science Advisory Board criticized the study because board members believed that the commodity "ground water cleanup" was not sufficiently well defined to allow a single interpretation of the respondents' answers to the survey. Whether this criticism is valid can only be proved or disproved by further scientific analyses. As an example of the study's possible limitations, the survey indicated a nonuse value component for ground water of $49.44 per
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Alternatives for Ground Water Cleanup household per year—close to the nonuse values estimated for preserving visibility in the Grand Canyon and for cleaning up hazardous waste sites in Colorado as determined in other contingent valuation studies (Rahmatian, 1987; Energy Resource Consultants, 1986). That the value survey respondents placed on this "good cause" is similar to the measured values for other "good causes" may signal problems. The sum of values people express in independent studies of willingness to pay for all good causes may exceed the disposable income of any one respondent (Kahneman and Knetsch, 1992). THE COMPLEXITY OF SELECTING CLEANUP GOALS Selecting ground water cleanup goals is not a simple matter: it involves consideration of health risks, ecological risks, costs versus benefits, and a variety of other factors—all of which are difficult to quantify with certainty. Different people interpret this uncertainty in different ways. For example, some view the uncertainty in the health risks of ground water contamination as an indication that the risks are insignificant, while others view it merely as an indication that science is limited in its ability to quantify what they perceive as a major risk. Similarly, some view the inability to place a precise dollar value on the economic damage caused by ground water contamination as proof that the economic damage is not significant, while others view it as proof only of the limitations of economics to adequately value important resources. Thus, some view existing ground water cleanup programs as having high cost while providing society with little benefit, while others view the programs as barely adequate to address an important environmental problem. The national policy debate over ground water cleanup goals must resolve these two conflicting extremes. The task of selecting ground water cleanup goals would be difficult enough without technologic constraints. However, as this report documents, present technologies will be unable to restore portions of a large number of sites. The limitations of technology, in the view of some people, provide added reason to reconsider whether current ground water cleanup goals are appropriate. Given the high level of uncertainty in the risks and economic damage created by ground water contamination, the committee believes that whether changes are needed in the policies for setting long-term cleanup goals can only be decided through policy debates; science can influence these debates, but value judgments must be the deciding factors. At the same time, however, the committee strongly believes that because existing ground water cleanup goals cannot be at-
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Alternatives for Ground Water Cleanup tained at a large number of sites, short-term objectives should be established at these sites to temporarily supersede long-term goals. Under the scenario the committee envisions, short-term objectives would be set based on the capabilities of current technologies at sites where long-term cleanup goals cannot be reached for the full site with current technology but the ability to reach them in the future cannot be ruled out. Access to portions of sites where contamination remains would be restricted or partially restricted. Periodically, the EPA would review whether technology had advanced to the point that the interim objective could be moved closer to the long-term goal. Short-term objectives would not be needed for the sites at which cleanup goals can be reached with current technology. In addition, short-term objectives might not be needed for another group of extremely complex contaminated sites where cleanup is highly unlikely even with new technologies; at such sites, technical impracticability waivers might be used to waive cleanup goals, as is done under current policy in the Superfund program. The next chapter explains the details of how policymakers would decide which sites should have interim objectives in addition to long-term goals. The setting of short-term objectives in situations where long-term cleanup goals cannot currently be achieved has precedence in existing environmental policy. For example, the Clean Water Act set an unenforceable national goal of ''zero discharge'' of pollutants for surface water but used "interim" enforceable objectives that recognized that achieving zero discharge was not technically feasible at the time the act was passed. In the Clean Water Act and under the scenario the committee envisions for ground water cleanup programs, the long-term goal provides the vision for national policy, while the interim objectives reflect the reality that there may be technical constraints to reaching the goal. The committee believes that interim objectives prevent the expenditure of resources trying to reach goals that are not achievable with current technology and more accurately communicate to the public what is possible with current technologies. At the same time, interim objectives do not rule out the possibility that at some future time new technological breakthroughs may enable the achievement of existing cleanup goals. They preserve the values that public policymakers believed were important when the nation's ground water cleanup programs were first implemented. CONCLUSIONS Based on an assessment of current ground water cleanup goals in light of the capabilities of ground water cleanup technologies, along with a review of the risks, costs, and benefits associated with ground water
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Alternatives for Ground Water Cleanup contamination and cleanup, the committee reached the following conclusions: Interim ground water cleanup objectives may be needed for portions of sites where health-based cleanup goals cannot be achieved with existing technology. The establishment of policies for setting long-term cleanup goals at sites requires consideration of many factors other than the capabilities of technology, including health risks, ecological risks, costs, benefits, and people's values. Changes in long-term cleanup goals therefore require debate in public policy arenas. However, the committee strongly advises setting short-term, technology-based objectives to temporarily supersede long-term goals at portions of sites where achieving the long-term, health-based goals is not possible with current technologies. The health risks of ground water contamination from hazardous waste sites are uncertain, but this uncertainty does not provide justification for changing long-term cleanup goals. The inadequate documentation of health risks derives from the general absence of information on human exposure to contaminated ground water and lack of information on the adverse effects of ground water contamination on humans. Given this lack of information, the relative degree of public health protection offered by one ground water cleanup goal, such as drinking water standards, in comparison to another goal, such as contaminant levels higher or lower than drinking water standards, cannot be quantified with accuracy. Ground water contamination can cause significant ecological damage at certain sites. Ground water remediation has generally focused on public health concerns. However, given the increasing evidence that ground water contamination can also damage important ecosystems, the ecological effects of unremediated contaminant plumes are important to consider when choosing a long-term ground water cleanup goal. At the site level, ground water cleanup goals can substantially affect cleanup costs. Removing 80 or 90 percent of the contamination generally costs much less than attempting to remove all or nearly all of the contamination. The magnitude of the cost difference depends on local economic factors, site characteristics, the cleanup technology chosen, and whether a containment system will be necessary if contamination remains in place. At the national level, the total benefits and the costs of existing ground water cleanup policies are both likely to be in the tens to hundreds of billions of dollars range—but these figures are highly uncertain. Many assumptions underlie existing estimates of benefits and costs,
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Alternatives for Ground Water Cleanup and there is no consensus on these estimates in the economics community. As a result, direct comparisons of the costs and benefits of various ground water cleanup policies must be used with caution. NOTES 1. These numbers are based on the committee's analysis of the EPA's Record of Decision data base. 2. Similar but separate regulations apply to the correction of leaks from landfills. 3. This figure is based on a key word computer search of the EPA's data base containing Records of Decision issued from 1982 to fiscal year 1991. 4. Uncertainty increases substantially when one aggregates cleanup costs from the site level to state, regional, and national levels. 5. The Carlin et al. estimate excludes sites outside the Superfund and RCRA programs, while the University of Tennessee estimate includes all waste sites. On the other hand, the Carlin et al. estimate includes costs under Superfund and RCRA unrelated to ground water cleanup, such as waste disposal costs. 6. The plume volume is defined as the volume of ground water containing dissolved TCE at concentrations above the detection limit (0.5 µg/liter). For this example, all of the TCE is either dissolved or adsorbed to solid materials in the aquifer; none is present as a dense nonaqueous-phase liquid. 7. Under the Reagan administration, the Office of Management and Budget required economic analyses of all proposed new regulations. 8. In the hypothetical situation described in this survey, the contamination originated from a leaking public landfill. "Complete cleanup" refers to building a concrete wall around the landfill down to the rock layer beneath it and pumping and treating the water outside the containment zone. 9. The researchers who carried out this survey attributed $4.12 of the $7.08 to nonuse values. REFERENCES Abelson, P. H. 1992. Remediation of hazardous waste sites. Science 255(5047):901. Arrow, K., R. Solow, P. R. Portney, E. E. Learner, R. Radner, and H. Schuman. 1993. Report of the NOAA Panel on Contingent Valuation. Rockville, Md.: National Oceanic and Atmospheric Administration. Brookshire, D., and D. Coursey. 1987. Measuring the value of a public good: an empirical comparison of elicitation procedures. Am. Econ. Rev. 77(4):554-566. Cantor, K. P., R. Hoover, P. Hartge, T. J. Mason, D. T. Silverman, R. Altman, D. F. Austin, M. A. Child, C. R. Key, L. D. Marrett, M. H. Myers, A. S. Narayana, L. I. Levin, J. W. Sullivan, G. M. Swanson, D. B. Thomas, and D. W. West. 1987. Bladder cancer, drinking water source and tap water consumption: a case control study. J. Natl. Cancer Inst. 79:1269-1279. Carlin, A., P. Scodari, and D. Garner. 1991. Environmental Investments: The Cost of a Clean Environment. Washington, D.C.:Island Press. Carlin, A., P. Scodari, and D. Garner. 1992. Environmental investments: the cost of cleaning up. Environment 34(2):12-20, 38-44. Clark, C. S., C. R. Meyer, P.S. Gartside, V. A. Majeti, B. Specker, W. F. Baliseri, and V. J. Ella. 1982. An environmental health survey of drinking water contamination by leachate
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Representative terms from entire chapter: