Click for next page ( 178


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 177
Rapporteurs' Reports Much of the success of the colloquium must be credited to WSTB members Lester Lave, James Mercer, Richard Conway, and Gordon Robeck, who acted as rapporteurs for the workshops on risk assessment/toxicology, hydrogeology, engineering, and regu- latory strategies, respectively. The colloquium steering committee provided them with the following list of questions for use in gen- erating discussion, with an emphasis on technical and scientific issues, during the workshop session. . What methods are available for setting goals or standards? How are they helpful? . What are some strengths and concerns related to these methods from a scientific, technical, or regulatory perspective? . What is the ability of existing methods to account for diverse conditions? What is the adequacy of the data base in applying the existing methods? . What uncertainties are associated with the methods and their predictions? . What are the most important issues the methods neglect? The following summaries of the workshops' efforts present the wide diversity of opinion, vast breadth of expertise, and singular 177

OCR for page 177
178 HAZARDOUS WASTE SITE MANAGEMENT approaches to the resolution of the issues of concern that charac- terized the entire colloquium. RISK ASSESSMENT/ TOXICOLOGY WORKSHOP Rapporteur: Lester B. Zaire The workshop participants decided to focus on risk assessment techniques for health and, most particularly, for cancer. Tools exist to examine other health end points, trauma, and ecological damage, but the participants felt constrained to leave these to another time and place. TOOLS FOR SETTING AMBIENT EN~ON~NTAI STANDARDS Four general approaches have been used to set ambient env ronmental standards. . '1- 1. Using political and other nonscientific approaches. These approaches do not attempt to use scientific data or criteria; nor do they attempt to specify risks or health outcomes. Rather, they grow out of political compromise or the imposition of one powerful group's goals. 2. Setting the standard at the background (or nondetectable level) plus some increment. For example, the standard for benzene in water could be nondetectability, or background or twice the background level. 3. Basing the standard on control technology and costs. Ex- amples include the various EPA air and water emissions stan- dards such as Best Available Control Technology (BACT) and New Source Performance Standards (NSPS). 4. Setting the standards by risk analysis to quantify the mag- nitude of the hazards and then by setting risk goals. The first three of these approaches involve the "implicit" bal- ancing of costs and risks. For example, the engineers determining the best-available technology consider the costs and control effi- ciency of each technology and implicitly decide which technologies are too costly for incremental control. As long as industry and the public have confidence in those making the implicit trade-offs,

OCR for page 177
RAPPORTEURS' REPORTS 179 this can be a good approach. If that confidence is lost, however, the balancing must be done explicitly, which requires risk analysis and goal setting. Criteria for Evaluating the Approaches The following criteria were deemed the most relevant in evalu- ating each of these approaches to setting standards: (1) efficiency/ effectiveness, (2) equity, (3) administrative ease, (4) transparency, (5) the qualitative and quantitative uncertainty of the approach, and (6) a miscellaneous category consisting of defensibility, resid- ual risk, and others. The first criterion refers to whether the goal is being accomplished and if so, whether it is being accomplished at the least cost. The second criterion refers to whether the var- ious parties are being treated fairly. Note that sometunes equity is defined by process (having one's "day in court") rather than by outcome (those who benefit must pay). The third and fourth criteria are somewhat similar. The third looks at whether the solution can be implemented simply and at low cost. The fourth asks whether the approach is so simple that the public and other parties understand how it works and see it as addressing their con- cerns. The fifth criterion focuses on the extent to which scientists are confident that their answer is qualitatively correct, and then on the range of plausible quantitative estimates. The last category refers to the ability of Congress and administrators to defend the resulting goals and the risk after the process has been lowered sufficiently to be accepted. The criteria are best illustrated by applying them to the vari- ous approaches. The first, political or arbitrary standard setting, is not efficient or effective; it may be equitable, although those who are unhappy are likely to complain that they had no chance to present their case. Standard setting is administratively sim- ple, although implementation may be extremely difficult. The approach is not transparent because the public and other parties are simply asked to trust the person making the arbitrary decision. There is likely to be great qualitative and quantitative uncertainty associated with the standard. Because the basis of the decision is unknown, it is not likely to be defensible. Also, the residual risk might be too high. In particular, this approach is faced with the efficiency-residual risk dilemma. It is likely to impose too high a cost or leave too large a residual risk. The background

OCR for page 177
180 HAZARDOUS WASTE SITE MANAGEMENT plus an increment criterion scores well on administrative ease, eq- uity, transparency, residual risk, defensibility, and uncertainty. Its principal problem is efficiency-it simply costs too much in most cases. Technology-based standards depend on the quality of the de- cisionmakers and the information they have. If the process is performed extremely well, it is likely to be efficient and admin- istratively simple, and have low residual risk and relatively low uncertainty. It will not be equitable, however, and so those who must bear the burden will view themselves as having been treated arbitrarily. Also, this approach is not likely to be transparent; thus the public can easily lose confidence. In fact, by the 1980s the first three approaches no longer enjoyed the confidence of the public and other parties. Environ- mental controls were too expensive for arbitrary or other political judgments. Although background seems a wonderful goal, it is incompatible with an industrial or other high-consumption soci- ety. Engineering judgments have become more complicated as a greater array of alternatives has emerged and as the control tech- nology has become more expensive. It is simply not feasible to rely on undocumented expert judgment in a highly emotional area with many different levels of control and cleanup available at very different cost levels. Thus, risk assessment and goal setting have emerged as the prime approach to standard setting by default rather than through an attractive display of the strong properties of this approach. Setting Risk Goals Estimating the risks of some hazard is only one step in a long process. Another necessary step is defining the safety goals: how safe is safe enough? Several approaches have been proposed for setting safety goals. In the 1980 "benzene decision, the Supreme Court mentioned significant and trivial (de minimis) risks, without ever attempting to define either. A significant risk was one so high that it was worthy of attention and presumably of control. A de minimis risk was so small that it was not worthy of attention. Beyond this, the court gave few clues as to how to define these concepts, and there has been little success by the agencies in implementing the notions. The Food and Drug Administration has defined a risk of one cancer per million lifetimes to be de

OCR for page 177
R-APPORTEURS' REPORTS 181 minimis. EPA has been somewhat less explicit in considering that risks on the order of one cancer per million lifetimes or per hundred thousand lifetimes are de minimis. Some researchers have used the notion of comparative risks. They examine situations that we routinely encounter and accept in our activities to infer the safety goals. For example, in smoking cigarettes, someone is implicitly accepting high risks of lung can- cer and heart disease. In eating peanut butter, one is implicitly accepting the risk of liver cancer from aflatoxin contaminating the peanut butter. Finally, some researchers have attempted to examine the safety implications of decisions made by federal regulatory agen- cies. The agencies had no explicit safety goals and instead agonized over each decision individually. Despite the individual decisions, a pattern seems to emerge that gives some general guidance. Nev- ertheless, setting safety goals is one of the most difficult steps in the process. Strengths and Weaknesses of Risk Aseesement and Management In focusing on risk assessment the greatest strength was seen as its internal consistency and its ability to make comparisons across chemicals and waste sites. Risk assessment is targeted to health outcomes, the area of greatest public concern. Furthermore, it gives quantitative estimates of the health risks. Finally, the method is able to deal with multiple chemicals and to offer an aggregate measure of risk for such chemicals "stews." In summary, risk assessment offers an intellectually appearing approach to a difficult problem. Its basic weakness stems from the difficulty of implementing this approach, the method for which is complicated and difficult to understand. Thus, few people understand the basis for the esti- mates or the objections raised by injured parties. There are rarely adequate data to implement the method, particularly with regard to individual exposures. Indeed, exposure data were identified as the primary source of uncertainty in current estimates. The com- plexity of the method means that it is difficult to communicate results and uncertainty to the public and to decisionmakers, a ma- jor weakness in a democratic society. The models currently in use were developed on the basis of somewhat plausible assumptions rather than on the basis of the underlying biology. In the last year

OCR for page 177
182 HAZARDOUS WASTE SITE MANAGEMENT or two, however, great progress has been made in understanding the biology of carcinogenesis, and recent work in pharmacokinet- ics has developed the foundation for much better risk assessment models. The group also discussed the extent to which the risk esti- mates had been validated. There has been some validation, but first, one must understand that all current risk assessment tech- niques are attempts to derive reasonable upper bounds to the risk level. They are somewhat analogous to "probable maximum floods." Thus, validation does not consist of asking whether the risk estimates are accurate indicators of what is found in epidemi- ological investigations. Because the risk estimates are reasonable upper bounds, one needs to ask whether the risk estimates have been found to understate the risks observed in the world. There have been a few cases in which this question could be answered, such as the bladder cancers from saccharin consumption; these cases find that the risk levels estimated by the models are upper bounds to what is measured in the world. The Strengths and Weaknesses of Setting Risk Goals Setting risk or safety goals requires public education and de- bate; as a result the strengths and weaknesses of the method are opposite sides of the same coin. Educating the public about safety issues and about tiny levels of risk is extremely difficult. Even statisticians have difficulty making decisions concerning small probabilities unless they do the calculations first. Yet because the United States is a democracy, there is no alternative to edu- cating the public sufficiently to select a system for managing toxic waste hazards. Equity also plays an important role in the debate because the public is concerned not only with the overall safety level but with how the risk is apportioned. If children are at high risk, for example, the public is concerned. Risk analysis has the ability to estimate risks to individual groups, and thus safety goals must be examined in detail. CONCLUSION The process of risk management and goal setting helps to focus the attention of analysts, scientists, decisionmakers, and the

OCR for page 177
RAPPORTEURS' REPORTS 183 public on the issues of critical importance. Thus, in an emotional, complicated world, these tools help to push aside the secondary issues and ensure that the important ones are highlighted; as a result the tools help to ensure progress. Risk assessment is still in its infancy, however, and there are large uncertainties, both qualitative and quantitative, associated with the estimates. Although advances in biology promise more certain estimates in the future, the primary reason for using risk assessment in setting standards is that nonscientific approaches, approaches that do not balance safety and costs, and approaches that do the balancing implicitly rather than explicitly are not accepted by the public and other interested parties. EPA's effort to bring the public into setting standards for the ARSARCO smelter in Tacoma, Washington, is an example of how difficult it is to educate the public about risk assessment and to discuss safety goals. Yet whatever the difficulties, it is unclear that there is any alternative to using risk assessment and setting safety goals. HYDROGEOLOGY WORKSHOP Rapporteur: James W. Mercer After discussing the colloquium papers the workshop group summarized the role of hydrogeologists in hazardous waste site management. That role is to use some methodology to estimate exposure from ground water contamination. Exposure calcula- tions are subsequently used with effects data in estimating the associated risk. Such exposures may be estimated on a generic ba- sis and the results used in setting policy, or the exposure may be estimated on a site-specific basis and the results used to implement policy. With this understanding as a foundation, the workshop ad- dressed six questions presented to all workshops. Discussions of the questions are given below under the following headings: Meth- ods Used in Exposure Estimation, Strengths and Weaknesses of the Methods, Methods' Electiveness Under Diverse Conditions, Associated Data Base, Associated Uncertainties, and Important Issues.

OCR for page 177
184 HAZARDOUS WASTE SITE MANAGEMENT METHODS USED IN EXPOSURE ESTIMATION Hydrogeologists use a variety of methods to estimate exposure at hazardous waste sites. These methods help us to understand existing conditions and to evaluate remedial actions. They include direct measurement, ground water modeling, theoretical calcula- tions, and expert opinion. Direct measurement includes tools and techniques normally associated with site characterization such as siting, drilling, and installation of monitoring wells; sampling ground water; and chem- ical analysis of those samples. Ground water modeling refers to the use of numerical and/or analytical solutions to simulate flow and transport in the subsurface. Theoretical calculations include statistical analysis and other mathematical expressions that are not considered part of ground water modeling. Finally, expert opinion refers to best professional judgment. STRENGTHS Al WEAKNESSES OF TEE METHODS Direct measurement or monitoring has the advantage of di- rectly observing concentration distributions. This method should be included even if other methods are selected. The disadvantages of this method are its costs and the problems associated with proper monitoring overt siting, well construction (making sure that a representative sample is obtained), and sample analysis. Also, this approach provides only a snapshot of the situation and not a prediction of the future. Ground water modeling is a valuable too! that aids site con- ceptualization and the relative evaluation of various remedial alter- natives. Modeling ground water flow is generally performed with confidence. Unfortunately, that confidence is greatly diminished when models are applied to organic transport. Such processes as sorption and degradation are not as well understood as flow, and rate constants describing these processes are generally unavailable. Thus, modeling organics has a great deal of uncertainty associated with it. Statistical techniques, such as time series analysis, may be helpful in predicting trends. These tools, however, require signifi- cant data and do not aid in improving our physical/chemical un- derstanding of solute transport. Other theoretical calculations- for example, geochem~cal relationships may indicate possible

OCR for page 177
RAPPORTEURS' REPORTS 185 reactions or transformations, but they cannot provide the reac- tion kinetics. Therefore, these methods also have uncertainty associated with them. Expert opinion is used throughout these methods. It is used to help site wells and to form conceptual models for testing and analyzing. It is also used to estimate ranges of values for certain parameters. Expert opinion by itself, however, without the above methods, is of limited value. METHODS' EFFECTIVENESS UNDER DIVERSE CONDITIONS All of the above methods, given the limitations discussed, work for diverse conditions if there are sufficient data. The uncertainty introduced by a lack of sufficient data must be addressed when us- ing any of the methods. For example, in a ground water modeling application, multiple simulations may be required in which both sensitivity analysis on uncertain parameters and scenario analysis on uncertain conditions are performed. ASSOCIATED DATA BASE As indicated throughout this discussion a major problem with all methods is the data or rather, the lack of it. The data re- quirements may be divided into two groups: site-specific and chemical-specific data. Site-specific data include hydrologic units, intrinsic permeability distribution, source terms, hydrodynamic dispersion, and so forth. Chemical-specific data include solubility, wettability, volatilization, biodegradability, and others. Participants in the workshop generally concurred in the be- lief that both kinds of data are lacking. The emphasis at haz- ardous waste sites is on chemical monitoring, and important hy- drologic data, such as intrinsic permeability, are often overlooked. In addition, the time frames associated with remedial investiga- tion/feasibility studies are generally less than 1 year. Thus, not even one annual cycle of hydrologic data will be available when the remedy is specified. Chemical-related data are also lacking, a cir- cumstance that is particularly true for multiphase flow problems and chemical transformations.

OCR for page 177
186 HAZARDOUS WASTE SITE AL4NAGEMENT ASSOCIATED UNCE1ITAINT~S The uncertainties associated with the four methods noted ear- leir have been discussed throughout this report. More uncertainty is associated with transport than with ground water flow. The sources of this uncertainty are complex processes, data limita- tions, and site variability. Because of these uncertainties, the prediction of future organic fates and their transport is very difficult. Although exact predic- tions cannot be made, our ability to predict is adequate enough to make many engineering decisions concerning remediation. I~O:RTANT ISSUES The following important issues were identified by the workshop participants: 1. The methods discussed in this report must be used by qualified people. Misuse of the methods obviously negates any value that might be assigned to them. 2. The communication of results is critical. This process should include the dissemination of enough information to allow the results to be reproduced, the assumptions and methods used to obtain the results, and the limitations and uncertainties associated with the results. 3. It is important that these methods be validated and that performance measures associated with these methods be verifiable. 4. Public education is important. Ground water character- ization and cleanup is a long-term process, with some cleanup standards exceedingly difficult to achieve. ENGINEERING WORKSHOP Rapporteur: Richard A. Conway The formal presentations at the colloquium emphasized the aspects of toxicology, hydrogeology (transport/transformation), regulatory strategy, economics, and public concerns in setting cleanup levels at hazardous waste sites. The role of engineering was elucidated in a following workshop.

OCR for page 177
RAPPORTEURS' REPORTS 187 The first step was to define what was meant by "engineering. Webster's defines engineering as "the science by which the proper- ties of matter and the sources of energy in nature are made useful to man in structures, machinery, and products." The operative word here is useful. Also encompassed by "products" presumably would be the categories of processes and operations. Thus, engineering transforms the findings of scientists (e.g., hydrogeologists and toxicologists) into products useful to man. In terms of water quality issues the workshop participants recognized that engineers play a role in developing useful models of trans- port and transformation; they agreed to limit their discussion to mitigation processes and operations, however, because engineering plays a unique role in setting water quality goals. DISCUSSION OF POSS~IE CHANGES ~ To ENGINEERING ROTE With material from the formal presentations of the collo- quium, a schematic of the process of setting cleanup goals was synthesized (Figure A). In this figure the cleanup goals that is, the site-specific levels of acceptable exposure or risk-are es- tablished by comparing release concentrations with background levels; exposure concentrations with accepted concentration stan- dards for chemicals in the various media; and the risk level with policy goals for acceptable risk. When discrepancies between any two of these inevitably are found, various mitigation strategies are applied until a level of risk is achieved at a cost; and degree of reliability acceptable to society. As shown in Figure A, mitigation strategies can be applied to prevent releases, to contain releases, or to treat the contaminated medium at the exposure point (see Table A for some alternative mitigation strategies). This is an iterative process; that is, various strategies are tested until an acceptable risk level is achieved. The process described above can take up to 4 years and cost several million dollars before remediation, a 2-year process itself, is even started. The workshop further explored a concept suggested by David Miller during the colloquium to the effect that the time and cost could be reduced markedly by starting studies of remedi- ation alternatives immediately after release characterization and well before the full risk assessment is completed (Figure A). Knowing what kind of remediation is feasible in terms of

OCR for page 177
188 HAZARDOUS WASTE SITE MANAGEMENT S i te Best ri 3 ti on Release Characterization - t Transport/ Transfonrtati on Ana 1 yS; S (Al 1 Media) i -1 1 Level Of l ra) Exposure ,_ Detelilli nati on 1\ ~ \ 1 \ 1 \ 1 \ \ l 1 I Standards of Chemicals in Va ri OUS bledi a I (Exposure I Criteria) Background Level S 1 ~1 ~ Cost g Effectiveness Data Base on A1 ternati ve Mi ti gati on Strategi es ( Engi neeri ng ) -1 1_' 1 ( a ) Dashed 1 i nes i ndicate PersDeCtiVes of some Site-Specific Acceptable environmental groups Exposure or Risk Levels and regul atory agencies (b) t)ash-dot-line is proposed earlier i nvol vement of eng i Deeri ng i n the standar~d-setting process Demographics h Envi ronmental Studi es _ Dose Response Assessment \ Consequence \ ~etet~lli nati on ~ ( Ri Sl( . Chdracteri zati on ) Proposed Prel imi nary Engi neeri ng Studies of Mi ti gati on Al ternatives ! 1 (b) i i i ! Pol icy Goals Of ~ AcceDtabl e pi sk FIGURE A The role of engineering in establishing cleanup goals as dis- cerned from colloquium presentations. reliability to achieve goals (uncertainty), time to reach goals, per- manency of goal attainment, and cost would provide direction for the risk assessment instead of its pursual in the abstract. The only factor keeping society from insisting on near-zero risk is the cost of attaining it. Hence, knowing something of the cost-effectiveness of engineered alternatives early in the process should markedly speed up the assessment and thus the final remediation. In addi- tion, factors that are critical to design are identified early and can be resolved during the hydrogeologic studies and not later as an add-on study. In a similar vein but from a different perspective, during the colloquium, Toby Page pointed out that factors like useful (cost- effective) engineering solutions should be more fully considered. When one tries to make an objective decision in this arena based on classic risk analysis (an inexact process with great uncertainty),

OCR for page 177
RAPPORTEURS' REPORTS TABLE A Some Alternative Mitigation Technologies 189 Activity Technology Excavation and offeite disposal Containment Treatment of wastes and plumes near release point Treatment of plumes at the drinking water wellhead Physical barriers (e.g., Blurry walls and caps, leachate collection) Incineration and other thermal treatment Stabilization, solidification for leaching control Soil flushing with water treatment Soil biologic treatment Pumping, treating, and recharging of ground water In situ biologic treatment of soil and ground water Chemical treatment (chemical reactions) Physical separation of contaminants for treatment (e.g., volatilization) Air stripping and activated-carbon adsorption Based in part on U.S. General Accounting Office, Hazardous Waste: EPA's Consideration of Permanent Treatment Remedies, GAO/ACED 86-178BR. Washington, D.C., July 1986. paralysis (inaction) can result. Subjective decisions often are ap- propriate in cases in which uncertainties are great. Knowing the effectiveness and cost of solutions is a component that helps a subjective decision. But as David J. Len pointed out the need for action should not be overemphasized; we should follow a policy of ready-aim-fire and not ready-fire-aim. (As Tom HelIman quipped, we should also avoid a policy of ready-aim . . ., ready-aim . . ready-aim . . ., ready-aim-fire.) Another observation of participants in the engineering work- shop was that remediation systems cannot be reliably designed for very low standards because design relationships are not proven down to those levels. Also, analytical methods with "practical detection limits" that is, reasonable detection levels based on available analytical technology, considering economic and techni- cal feasibility at or below the proposed cleanup standards are needed for proper evaluation. Those individuals involved in risk

OCR for page 177
190 HAZARDOUS WASTE SITE MANAGEMENT assessment should keep this in mind as they debate goals in the Tow micrograms-per-liter range. In addition, engineers have a responsibility to describe the use- fuIness of their design solutions in terms of effectiveness, reliability (uncertainty), the time it takes to accomplish them, permanency, and cost, in descriptions that are understandable to the public. Specific uncertainties with the flushing method of soil cleanup, the extraction/treat/recharge method of plume mitigation with its associated problem of hysteresis because of slow Resorption, and the longevity of plastic covers were identified. Also, much less experience exists for in situ subsurface remediation compared to surface treatment; consequently, the former is less reliable at this time. Designs should be favored that fad] in a safe way, that is, there is little risk to the community, and corrective action can easily be taken. Finally, the public needs to be informed of constraints in the utility of remedial technology. Engineers need to get across to decisionmakers who are trusted by the public what can and cannot be done at a cost acceptable to society. For example, a qualitative term like exorbitant cost could be expressed quantitatively in terms of very low reductions in risk for the additional cost (Figure B). Public expectations need to be tempered by the ability to pay which is what the public ultimately does, no matter from which pocket the funds originally came. Also incumbent on engineers is the need to continue to seek more elective, lower cost solutions to this problem. Further- more, additional arbitrary political barriers to the implementation of innovative options should be removed; in this manner, more field sites could serve as engineering "laboratories" and potential demonstration projects when risk to the public is minimal. CONCLUSIONS Engineering solutions that are cost-effective should be dis- cussed early in the process of setting water quality standards; that is, in selecting a method for dealing with a particular hazardous waste site, consideration should be given to achievable engineering solutions. . Requiring a particular site to be rehabilitated to back- ground or parts per billion levels often is not achievable with present-day engineering methods.

OCR for page 177
RAPPORTEURS' REPORTS Site Risk ~ . Larc risk reduction per unit cost FIGURE B Cost-effectiveness. 191 Low (de minimus) risk reduction per unit cost Range for close evaluation Site Remediation Cost . Designs should be pointed toward rugged concepts that are of a safe/faiT perspective rather than a fragile design in which failure can result in serious consequences. ~ Engineers should take a leading role in helping to inform the public and in some cases regulatory staff of the reliable en- gineering aspects of hazardous waste site management and water quality issues. . Engineers need to communicate with the public on the al- ternative solutions to a particular site cleanup: the cost versus the level of pollutant cleanup, the reliability and uncertainty involved, and the permanence of the alternatives. REGULATORY STRATEGIES WORKSHOP Rapporteur: Gordon Robecl~ The methods used by some states and EPA to set water quality goals or standards rely heavily on a risk assessment that involves setting some numerical concentration limit at a water use point. Reducing carcinogens to a risk of lo-6 would be one example.

OCR for page 177
192 HAZARDOUS WASTE SITE MANAGEMENT Several workshop participants contended that this method has not worked very well for federal cleanup cases and claimed that available money, the time to do the cleanup, and feasible tech- nology were and still are the driving forces for action. These people seemed to prefer a goal based on future land and water use, in addition to one that gives more weight to anticipated ex- posures. Such a policy would give the local citizens more control over how much cleanup they wanted and how much money should be spent on a specific site. A third faction proposed that the most straightforward goal was simply to clean up the site to its original state. One of the weaknesses of trying to calculate risk is that many toxicants singly or in combination-have not been evaluated for their health effects; thus, the total exposure from air or water, or to the skin, for present or future users of the land and water is difficult to estimate. Consequently, many believe a negotiated technical solution to pump and treat ground water to the level of surface water resources is the most practical and the quickest way to confine the ground contamination. Although this approach has been conducted successfully at some locations with the help of pre- dictive models and strategically placed wells for testing the move- ment and quality of water, there is still much to be learned about contaminant retardation and biotransformation in the anaerobic zone. Incidentally, the federal health program is making an ef- fort to determine the health effects of 100 chemicals that may be involved in such contamination, with perhaps hundreds more to be considered in the distant future. Some estimate these evaTu- ations may cost as much as $1 million-$4 million per chemical, and even when they are completed, many in the field doubt that the information will change the choice of technology for remedial action. Others realize that health effect determinations and risk assessment analysis must go forward and that with time and ef- fort a stronger basis and understanding will support the remedial actions and promote public confidence. To expedite the cleanup process, EPA has proposed cIassify- ing waters in three categories and thus guiding the decisionmaker as to where, when, and how much cleanup should be required at any one site. Some workshop participants thought that the sys- tem of permitting discharges, as allowed by the Clean Water Act, would be a fairer and more practical way of protecting a large aquifer from excessive contamination. One state representative

OCR for page 177
RAPPORTEURS' REPORTS 193 maintained that the decision tree process was working in his state, but he also admitted that, initially, there was a lack of knowI- edgeable well drillers, consultants, and stab people to aggressively handle all the major cases. This individual stated, however, that there has been rapid improvement in technology and personnel so he is encouraged about future cleanup and source control. Other workshop participants were concerned about the lack of oversight and reliable statistics to help measure the rate of progress in the state or federal cleanup programs. Many people fee! a great frustration with the congressional mandate to clean up to background levels, and they believe that in 5 more years there will be great disappointment with the slow rate of such cleanups. They think much of the effort must be made by technical people to educate Congress and the public in general as to what can be done with the available funds; they also think it is necessary to convey how impossible it is going to be to achieve original or background levels at all major sites. In any event the workshop participants anticipated the need to be open and flexible because circumstances will undoubtedly cause other changes in legislation and in the availability of cleanup funds.

OCR for page 177