Poison in the Vadose Zone

Press Release & Statements

Table of Contents

Preface

Executive Summary

Chapter I: Introduction to INEEL and the water resources of the region

Chapter II: Current Contamination of Aquifer

Chapter III: Future threats: Radioactive, mixed, and hazardous buried waste at INEEL

Chapter IV: Policy Considerations for Clean-up

Appendix A: The Snake River Plain aquifer

Appendix B: Maximum Contaminant Levels in Drinking Water

Appendix C: Properties of Relevant Chemicals

Appendix D: Fate of Pollutants in the Soil

Glossary

References

The Snake River Plain aquifer is the most important underground water resource in the northwestern United States. The U.S. Environmental Protection Agency (EPA) has designated this aquifer as a sole source aquifer, because it is the only source of drinking water for 200,000 people in southern Idaho. It is also a major source of irrigation water for regional crops, notably potatoes, and for fisheries. The produce grown in Idaho is eaten throughout the United States and in many other countries, including Japan, Canada, and Mexico.¹ Idaho's trout farms, which rely on the groundwater at Thousand Springs, produce 75 percent of the commercial rainbow trout eaten in the United States.²

The Idaho National Engineering and Environmental Laboratory (INEEL) sits directly above 2,300 square kilometers (890 square miles) of this aquifer. For the second half of the twentieth century, large quantities of radioactive waste, including plutonium-bearing waste, were dumped into shallow pits and trenches or directly injected into the aquifer at INEEL from nuclear weapons production operations there and from other sites around the United States. The existing base of information does not permit a thorough assessment of the risks posed by these wastes. But there is enough evidence of current contamination of the aquifer under the site, and of the potential for rapid migration of very long-lived radionuclides like plutonium, to establish that remedial action is urgently needed if the Snake River Plain aquifer is to be protected for future generations.

Direct injection of radioactive and hazardous substances into the Snake River Plain aquifer and the discharging of wastes into percolation ponds have resulted in contamination plumes in the aquifer, including plumes of tritium, strontium-90, iodine-129, and trichloroethylene (TCE).³ These contaminants have areas of their plumes that are above the maximum contaminant level (MCL) set by the U.S. EPA under the Safe Drinking Water Act. Plutonium and americium have also been found in the vadose zone (the unsaturated zone between the ground surface and the water table) and in the aquifer.

From the 1950s to the 1970s, an enormous amount of radioactive and hazardous waste was dumped in cardboard and wooden boxes and 55-gallon steel drums in shallow dumps at INEEL. This waste contains more than a metric ton of plutonium-239/240, which is enough to make about 200 nuclear bombs. The total amounts of some individual long-lived radionuclides, including plutonium and americium, are so large that each one by itself could pose a major threat to the Snake River Plain aquifer. There are also large amounts of hazardous chemicals in the buried wastes, some of which have traveled rapidly into the aquifer. The DOE is continuing to dump low-level radioactive wastes, which can contain long-lived radionuclides, into these pits and trenches. The combined threat from the radioactive and hazardous chemicals in the buried wastes is enormous.

The best available evidence indicates that the rate of migration of some of the most dangerous constituents of the waste, such as plutonium and americium, is much faster than anticipated. Several mechanisms of rapid waste transport have been identified through a combination of field, laboratory, and theoretical work in the last three decades. The evidence of rapid migration of transuranic radionuclides at INEEL is given further support by research at other U.S. Department of Energy sites, where plutonium has also been found to migrate more rapidly than anticipated under a variety of circumstances.

While there is some controversy about the validity of the positive findings of plutonium in water samples from the Snake River Plain aquifer, detections of plutonium deep in the vadose zone further verify that plutonium is rapidly migrating.

Despite some very good scientific work on the transport of radioactive and hazardous materials through the vadose zone, the DOE has failed to act on it to protect the Snake River Plain aquifer. For instance, a 1976 report of the U.S. Geological Survey (USGS) presented extensive evidence of rapid contaminant transport at INEEL. Yet, the problem of buried wastes has been inadequately addressed during the twenty-five years since its publication.

While each of the pollutants for which data are available is below the allowable limits in the drinking water wells on the INEEL site, the combined burden of hazardous chemicals exceeds the allowable level of contamination in one of the workers' water supply systems. The level of carbon tetrachloride alone in one of the drinking water wells is 95 percent of the maximum contaminant level. Although the drinking water limits for non-radioactive contaminants are set individually and not considered on an additive basis, as is done in regulations involving radionuclides, it is a prudent public health practice to consider these cumulative risks. These regulations also do not apply to private water wells. The drinking water supply of workers is currently treated so as to conform to safe drinking water limits.

Contamination in the Snake River Plain aquifer is still largely under the INEEL site. Two contaminant plumes have migrated the farthest: tritium and strontium-90. The off site radioactivity for these two radionuclides is less than allowable drinking water limits. Available evidence indicates that the most long-lived radionuclides, notably the transuranics such as plutonium, may not have migrated very far. Therefore, it is still possible, through a proper waste retrieval and processing program, to protect the aquifer. However, the rapid migration of radioactive and hazardous chemicals, the large amounts of these materials in the pits and trenches at INEEL, the substantial uncertainties in migration rates under various conditions, and the current contamination of the Snake River Plain aquifer with transuranic radionuclides under the site point to the need for urgent action to protect the aquifer.

Once the aquifer becomes contaminated at levels that exceed drinking water standards for long-lived radionuclides, the problem will be essentially irreparable. The technology for cleaning up large amounts of water contaminated with mixtures of volatile organic compounds and long-lived radionuclides to safe drinking water standards does not exist today.

Americium-241 is one of the most important of the alpha-emitting radionuclides in terms of its potential to pollute the Snake River Plain aquifer. It is relatively soluble in water, and hence, moves with the groundwater. Americium-241 has a half-life of 432 years. Water in the aquifer travels from under INEEL to the Magic Valley, southern Idaho's most productive agricultural region, in about half that time. Some americium-241 has already migrated through the vadose zone into the aquifer. The highest concentration of americium-241 found in the groundwater was 1.97 picocuries per liter in 1997. The levels of americium-241 are still below allowable drinking water limits (15 picocuries per liter), and no plume has as been identified. But considering that the amount of time that has elapsed since the waste was buried is far shorter than a single half-life of americium-241, and that knowledge about transuranic radionuclide migration has many gaps, it is not possible to predict the fate of the americium-241 with confidence. Preventing pollution of the aquifer depends mainly on limiting the amount of americium available for transport by recovering transuranic buried wastes from the pits and trenches into which they were dumped.

Iodine-129 is more soluble than americium and there is already a plume of it in the aquifer. The most contaminated well with iodine-129 had a concentration of 3.82 picocuries per liter in 1991 (its maximum contaminant level is 1 picocurie per liter). In 1991, iodine-129 from waste disposal at INEEL was detected in an off-site well at levels much less than the allowable drinking water standards. However, even though discharges of iodine-129 to the environment have stopped, the current source of iodine-129 in buried waste presents a serious problem because iodine-129 has a half-life of 17 million years. Despite the fact that there is a known plume of iodine-129, neither DOE contractors nor the U.S. Geological Survey (USGS) appear to have made any measurements of this radionuclide in the groundwater since 1992.

More than a metric ton of plutonium-239/240 is buried at INEEL. It presents a security concern should control of the site be lost, because that amount is enough to make more than 200 nuclear bombs. In other words, the pits and trenches at INEEL are potential plutonium mines.

The proliferation and environmental risks arising from so much plutonium in the buried wastes are illustrated by a controversy as to whether an accidental nuclear criticality gave rise to a fire in a waste barrel in 1970. The report on that fire is still classified. It is not well established whether any of the containers originally had enough plutonium to go critical (a spontaneous uncontrolled nuclear reaction) if they fill up with water. But plutonium in the buried wastes could leak and accumulate in a small volume of soil, which could lead to an accidental criticality in times of heavy rainfall or flooding.

The evidence from groundwater sampling so far indicates that plutonium migrates far more slowly than americium. Nonetheless, although plutonium does not appear to have migrated far and has not formed a plume, its migration rate through the vadose zone to the aquifer has been orders of magnitude faster than those assumed by the policy of shallow-land dumping. The half-life of plutonium-239 - more than 24,000 years - is far longer than that of americium-241. How the migration of plutonium will unfold, and how the climatic conditions of the site will change over such long periods, is unknown. Therefore, the long-term risks of leaving plutonium in the buried wastes are substantial from the environmental as well as the security point of view.

While most highly radioactive wastes at INEEL arising from reprocessing have been calcined and put into stable solid form for storage, 6,740 cubic meters of liquid waste, containing 2.6 million curies of radioactivity, were still stored at INEEL in 1997.⁴ Given the large amount of radioactivity involved, this waste poses a threat to the groundwater in cases of spills or other accidents.

The variety, combination, and amounts of wastes, the poor records, the deterioration of containers over time and the presence of combined flammable, explosive, and radioactive materials are factors that make the recovery of buried wastes difficult and complex. A large part of the difficulty arises from the fact that no existing technology can characterize the wastes fully before retrieval due to their complexity and heterogeneity. The safety risks to workers associated with this lack of knowledge need to be factored into the approaches that will be used for retrieval and processing (see recommendations).

Remediation programs are important for reducing the burden of hazardous non-radioactive materials in the vadose zone. For example, DOE is operating a vapor-vacuum extraction program to remove some of the volatile organic chemicals in the vadose zone below the Radioactive Waste Management Complex. A pump-and-treat program to remove trichloroethylene (TCE) from the Snake River Plain aquifer beneath the Test Area North has operated since 1996. In November 2000, DOE proposed using bioremediation to remove TCE from the most contaminated area (hot spot) under Test Area North. However, the proposed program changes would lower the clean-up goals for removal of contaminants, leaving a larger amount to "natural attenuation," which is the reduction of contaminant concentrations in the aquifer through radioactive decay, dilution, and dispersion. This will take an unacceptably long time. Organic contaminant removal is not only important in itself, but may also help to reduce the rate of transuranic radionuclide migration through the vadose zone.

The DOE Environmental Management program has not established the right priorities for waste management and instead has wasted enormous sums of money on poorly designed projects. A culture of denial seems deeply embedded with regard to major environmental problems, notably the threat posed by buried wastes. Insufficient resources are being devoted to clean-up of the dumped buried transuranic wastes, while far greater priority is being given to shipping the stored transuranic wastes, which are kept in relatively secure conditions indoors, to the Waste Isolation Pilot Project (WIPP) in New Mexico.

There is little prospect that the right priorities will be set and clean-up accomplished under the present institutional arrangements. On the contrary, the renewed emphasis on nuclear weapons will likely further decrease the priority given to clean-up and the quality and quantity of effective resources devoted to it.⁵

There are four urgent priorities for the protection of the Snake River Plain aquifer:

• Discontinue dumping waste into pits and trenches and percolation ponds

These priorities are needed to ensure that the Snake River Plain aquifer will remain usable and not be threatened by the wastes dumped in pits and trenches, released into percolation ponds, or leaked from waste tanks and pipelines.

A thorough, site-wide remediation of the vadose zone, expanding on and improving current programs as well as making greater use of innovative technology, is needed. Hazardous organic materials, such as carbon tetrachloride and trichloroethylene (TCE), are highly toxic pollutants that could mobilize faster transport of radionuclides through the vadose zone. The remediation of highly contaminated vadose zone areas at INEEL should, therefore, be a high priority. The DOE should not use the limited understanding of contaminant transport as an excuse to leave the buried waste in the ground. On the contrary, the limited understanding and the difficulty of the problems should be a spur to make the recovery of buried waste and the remediation of the vadose zone among its highest priorities. The stakes are very high. Doing nothing or simply monitoring the growing problem may result in irreversible damage to the Snake River Plain aquifer.

Our other recommendations are as follows:

While there is a substantial amount of groundwater monitoring already conducted, it is inadequate for the purpose of analyzing the migration of transuranic radionuclides, notably plutonium, which have not formed plumes. A more focused and open effort needs to be carried out to ensure that a thorough, rigorous, and effective program of measurements and analysis is conducted. Such a program can probably be conducted within existing resources by rethinking goals of the program and hiring contractors according to their ability to meet the goals of the program.

Recent work on the transport of contaminants has revealed that long-standing simple assumptions about the transport of radionuclides were wrong, that the phenomena are very complex, and that there are serious gaps in knowledge of contaminant transport. The existing research on this issue needs to be expanded into a comprehensive and sound program of scientific research. The future health of a large portion of U.S. water resources depends on it.

DOE has tended to minimize findings of contamination and obscure the need for remedial action by suggesting that the results may be due to factors in the measurement process, such as cross-contamination, rather than to actual pollution in the aquifer. A more frank disclosure, noting the uncertainties but also the policy implications of those uncertainties, is needed. When measurements of trace quantities of pollutants are involved, there can be and often are real uncertainties about the interpretation of the results. But policy needs to be made in light of these uncertainties, and should favor clean up. Moreover, there should be far broader public disclosure and far more thorough monitoring programs when there are uncertainties concerning plutonium and other pollutants. More thorough discussion with the public that involves fewer unwarranted reassurances that there are no problems in the face of indeterminate results would add much needed accountability and would contribute to improving clean-up performance.

Since it will be impossible to fully characterize the wastes prior to retrieval and processing, the approach that is used to carry out these tasks should take that fact into account. Specifically, the approach should learn lessons from past failures at INEEL and elsewhere. Some of these failures, including INEEL's Pit 9 project, are documented in IEER's 1997 report, Containing the Cold War Mess.⁶ Our suggested approach has the following elements:

• DOE should use highly modular and small-scale processing lines, each with some flexibility as to the waste composition it could handle;
• DOE should use remote recovery and processing techniques;
• The recovery of waste should be conducted in an inert environment if possible;
• The processing of waste should be done in explosion-proof structures that would protect workers and the environment in case of fires or explosions; and
• DOE should process waste remotely in relatively small batches so that explosions and fires can be contained within structures where no workers are present.

Some of the wastes containing significant amounts of plutonium need to be recovered for security reasons, while the rest need to be recovered in order to protect the Snake River Plain aquifer. Since accurate characterization is not possible prior to recovery, the goal of as complete recovery of buried wastes as possible would be a prudent one. Due attention will have to be paid to preventing accidental criticalities during processing of recovered buried wastes.

Despite the availability of much sound science and growing understanding of the nature of the threats posed by the environmental legacy of the Cold War, the DOE and its contractors have proved unable to carry out a sound clean-up program. The DOE's process for creating clean-up projects and selecting contractors has not measured up to the importance of the endeavor. Contractors for clean-up should be selected according to the task at hand, with strict criteria for expertise and experience relevant to the specific job, as well as for accountability and openness. At sites where production-related activities are still going on, there is a conflict between the goal of environmental cleanup and nuclear weapons-related goals. This is a more complex problem that requires more comprehensive institutional restructuring. Some options are mentioned in Chapter IV.

We recommend that these clean-up standards should include:

• a guideline involving doses "as low as reasonably achievable" (ALARA) of up to 2 millirem per year to the maximally exposed person; ⁷
• a standard of a maximum exposure of 10 millirem per year to the maximally exposed person from all pathways arising from the INEEL site, including the food pathway;
• sub-limits to the maximum dose involving the safe drinking water standards, which limit dose to 4 millirem to the critical organ from drinking water alone from most radionuclides;
• inclusion of consideration of cancer risks from hazardous materials and reduction of maximum permissible radiation exposure when exposure to hazardous materials is also present; and

• consideration of non-cancer risks and risks due to synergisms between various hazardous and radioactive materials.

7. The ALARA limit has been a general approach to radiation protection that mandates reduction of exposures below the standards that must be met. The ALARA limit is a guideline conditional on technological and economic factors.