ARCHAEOLOGY AND PUBLIC PERCEPTION 

OF A TRANSSCIENTIFIC PROBLEMDISPOSAL OF TOXIC WASTES IN 

THE UNSATURATED ZONE 

U.S. GEOLOGICAL SURVEY CIRCULAR 990 

ARCHAEOLOGY AND PUBLIC PERCEPTION 

OF A TRANSSCIENTIFIC PROBLEMDISPOSAL OF TOXIC WASTES IN 

THE UNSATURATED ZONE 

By Isaac J. Winograd 

U.S. GEOLOGICAL SURVEY CIRCULAR 990 

1986 
DEPARTMENT OF THE INTERIOR 

DONALD PAUL HODEL, Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

Library of Congress Cataloging-in-Publication Data 

Winograd, Isaac Judah, 1931-

Archaeology and public perception of a transscientific problem. 

(U.S. Geological Survey circular ; 990) 

Bibliography: p. 8 

Supt. of Docs. no.: I 19.4/2:990 

I. Hazardous wastes-Environmental aspects. 2. Hazardous waste sites-Environmental aspects. 

3. Environmental archaeology. I. Title. II. Series. 

TD811.5.W56 1986 363.7'28 86-600356 

Free on application to the Books and Open-File Reports Section, 

U.S. Geological Survey, Federal Center, Box 25425, Denver, CO 80225 
CONTENTS 

Page 

Abstract ........................................................................... . 

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Unsaturated zone disposal of solidified toxic wastes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

Evaluation of proposed toxic-waste repository sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

Potential applications of archaeology to toxic-waste disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

Efficacy of thick unsaturated-zone environments for isolation of solidified toxic wastes . . . . . 4 

Future human intrusion into toxic-waste burial sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

Identification of durable natural and manmade materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

Summary........................................................................... 8 

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

References cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

III 

Archaeology and Public Perception of a 

Transscientific Problem- Disposal of Toxic Wastes in 

the Unsaturated Zone 

By Isaac J. Winograd 

ABSTRACT 

Predicting the effects of toxic-waste disposal on the environment over periods of millenia to hundreds of millenia is a transscientific problem; that is, one not fully addressed by quantitative 

scientific and engineering endeavors. Archaeology is a pertinent 

adjunct to such predictions in several ways. First, and foremost, 

archaeological records demonstrate that delicate, as well as 

durable, objects buried in thick unsaturated zones of arid and 

semiarid environments may survive intact for millenia to tens of 

millenia. This successful preservation of Late Paleolithic to Iron 

Age artifacts provides independent support for the tentative 

favorable conclusions of earth scientists regarding the general utility of thick unsaturated zones for toxic-waste isolation. By analogy 

with the archaeological record, solidified toxic wastes of low 

solubility that are buried in arid unsaturated zones should remain 

isolated from the environment indefinitely; modern man 

presumably should be able to improve upon the techniques used by 

his ancestors to isolate and preserve their sacred and utilitarian objects. Second, archaeological evidence pertinent to the fate of objects buried in unsaturated zones- although qualitative in nature 

and subject to the limitations of arguments by analogy-is meaningful to the public and to the courts who, with some scientists and 

engineers, are reluctant to rely exclusively on computer-generated 

predictions of the effects of buried toxic wastes on the environment. Third, the archaeological record issues a warning that our 

descendants may intrude into our waste disposal sites and that we 

must therefore take special measures to minimize such entry and, 

if it occurs, to warn of the dangers by a variety of symbols. And 

fourth, archaeology provides a record of durable natural and manmade materials that may prove to be suitable for encapsulation of 

our wastes and from which we can construct warning markers that 

will last for millenia. For these four reasons, archaeologists must 

join with earth scientists, and other scientists and engineers, in addressing the likely fate of soli.dfied toxic wastes buried in the thick 

(200-600 m) unsaturated zones of arid and semiarid regions. Indeed, the input of archaeology might be crucial to public acceptance of even the most carefully chosen and technically sound 

waste repository. 

INTRODUCTION 

Alvin Weinberg (1985) used the term transscientific to describe certain environmental problems that, 

while requiring the close attention of scientists and 

engineers, are not likely to be solved by science. For 

example, in matters such as unraveling the health effects of low-level ionizing radiation- in an environment containing numerous other potential mutagens 

and carcinogens-Weinberg (1985) suggested that 

both the general public and governmental regulators 

might have to lower their expectations for quantitative answers from science and engineering. The 

disposal of certain highly toxic wastes, such as highlevel radioactive waste, is another transscientific 

issue. Earth scientists, in collaboration with chemical 

engineers, material scientists, and others, are being 

called upon to predict the environmental fate of highlevel radioactive wastes for periods of millenia to 

hundreds of millenia. Such predictions- to be 

generated by complex mathematical models that synthesize knowledge from numerous disciplines- are 

of necessity tenuous because a data base with which 

to calibrate such models does not now exist, nor is it 

likely to exist prior to the filling and sealing of the 

first waste repository. Simply put, we do not have the 

geotechnical experience with which to evaluate the 

reliability of model predictions even for centuries. 

The time dimension, alone, relegates high-level 

radioactive waste disposal to the realm of transscientific issues. 

This paper was written to suggest that, while quantitative analysis of the fate of buried toxic wastes is 

unlikely, by itself, to prove adequate, highly perti-

. nent qualitative evidence bearing on this complex 

matter resides in the field of archaeology. Such 

evidence may enable the scientist, the regulator, and 

the general public to convince themselves that 

solidified toxic wastes may be safely disposed of in 

carefully selected underground environments, even in 

the absence of quantitative proof. The author hopes 
that this paper will generate interest among archaeologists in applying their knowledge to the 

burgeoning, global, transscientific problems of toxicwaste disposal. 

UNSATURATED ZONE DISPOSAL OF 

SOLIDIFIED TOXIC WASTES 

Toxic wastes, whether of industrial, agricultural, 

or municipal origin, are being disposed of in two 

principal ways (National Research Council, 1983, 

fig. 2): (1) conversion to less hazardous or nonhazardous forms by incineration, chemical neutralization, biological alteration, industrial recycling, or 

dilution and (2) perpetual storage or disposal by 

placement in surface impoundments or landfills, injection into brine aquifers, or burial (in solid form) in 

· thick unsaturated zones 1 in arid regions. As a result 

of recent dramatic failures of some early landdisposal efforts- Love Canal being a prime example- considerable attention is being focused on 

waste conversion rather than on land-disposal 

methods. Yet, not all wastes are amenable to waste 

conversion, and some converted wastes still leave a 

volumetrically small, but toxic, residue requiring 

perpetual storage or disposal. Thick (greater than 150 

m) unsaturated zones, in arid and semiarid regions, 

have been identified (Winograd, 1972, 1974, 1981; 

Wacks and others, 1981; Roseboom, 1983; Wollenburg, Yang, and Korbin, 1983; and National 

Research Council, 1983) as potentially favorable environments for the disposal of the most toxic of the 

Nation's wastes, particularly solidified high-level 

radioactive waste. Archaeology can make several major contributions to the evaluation and future use of 

thick unsaturated zones, which the National 

Research Council (1983, p. 71) referred to as a "National asset in achieving a solution to the wastedisposal problem." 

The unsaturated zone in many parts of the 

Southwestern United States exceeds 150 m in 

thickness, and zones this thick encompass a minimum volume estimated to be about 22,000 km3 (M.S. 

Bedinger, U.S. Geological Survey, oral commun., 

1984). As a direct result of the search for sites 

suitable for disposal of radioactive wastes, it became 

apparent in the 1970's, that unsaturated zone environments had excellent potential for isolating 

1

The unsaturated zone is the soil and underlying rock between the land 

surface and the water table. In portions of the Southwest United States, such 

zones are hundreds of meters thick and permit burial of wastes at depths 

precluding exhumation by erosion. 

2 

solidified toxic wastes from the hydrosphere for 

millenia to perhaps hundreds of millenia. The attractive features of these arid and semiarid environments 

for waste isolation, as identified in preliminary 

studies (Winograd, 1972, 1974, 1981; Roseboom, 

1983) include (1) low moisture flux, (2) high sorptive 

capacity of selected rocks for radionuclides, and (3) 

the opportunity to use natural and manmade 

capillary barriers and other engineering structures to 

divert the meager moisture flux from contacting the 

wastes. Potential concerns about the long-term efficacy of such environments were also identified and 

include (1) the potential for future human intrusion 

into relatively shallow burial sites, (2) the increase in 

recharge and rise of water table that might accompany future pluvial climates, (3) the effects of erosion 

and, in some areas, tectonism, and (4) the absence of 

detailed studies of the soil physics of such environments. Briefly, thick unsaturated zones appear 

very attractive for the permanent disposal of 

solidified toxic wastes, particularly those wastes not 

amenable to other treatment, because water flow, the 

chief pollutant-transporting mechanism, is minimal. 

Detailed studies of the soil physics, geochemistry, 

and rock mechanics of these environments are in progress at several universities; at the Sandia, Los 

Alamos, Lawrence Berkeley, and Livermore National Laboratories; and at the U.S. Geological 

Survey. 

EVALUATION OF PROPOSED TOXIC-WASTE 

REPOSITORY SITES 

Selection of new sites for disposal of the Nation's 

most toxic wastes, such as high-level radioactive 

wastes, will be a lengthy process involving detailed 

geotechnical investigations, numerous public hearings, and, most likely, litigation. The nature of the 

geotechnical work being done with regard to the 

disposal of high-level radioactive wastes is outlined in 

this section; similar studies undoubtedly will be required prior to the disposal of other types of toxic 

wastes. 

To hedge against uncertainties, the currently accepted philosophy of radioactive-waste disposal is 

one of multiple barriers or, in engineering parlance, 

"defense in depth" (Interagency Review Group on 

Nuclear Waste Management, 1978). That is, a redundancy in safety is sought by using a variety of means 

to ensure isolation of the wastes from the hydrosphere and biosphere. In the case of high-level 

radioactive wastes, four barriers to radionuclide 
migration are receiving attention. The first barrier is 

a waste form of very low solubility, such as glass. To 

hedge against possible radionuclide release caused by 

devitrification, the waste-bearing glass may be put 

into a metallic or ceramic canister and even surrounded by clay or zeolite minerals. (The resulting 

product is referred to as a waste package.) A second 

major line of defense is a host rock that, ideally, contains little ground water to dissolve radionuclides 

from the waste package. A third line of defense is the 

sorptive capacity of host~rock minerals for the radionuclides; sorption can result in nuclide migration 

rates one to several orders of magnitude slower than 

the velocity of the transporting vadose2 or ground 

waters. The fourth line of defense is the occurrence 

beneath (in the case of the unsaturated zone) or 

within (in the case of saturated zone) the site of slowly moving ground water that is remote from points of 

present or likely future use. The relative importance 

of these barriers is, not surprisingly, highly site 

specific. 

The ability of each of these barriers to prevent or 

retard radionuclide migration is undergoing extensive 

studies at three sites currently being evaluated for the 

disposal of high-level radioactive wastes: the Waste 

Isolation Pilot Plant site in Permian age salt beds of 

southeastern New Mexico, the Basalt Waste Isolation 

Plant site in Tertiary basalts at Hanford, Washington, and the Yucca Mountain site in unsaturated Tertiary welded tuff at the Nevada Test Site. The 

Materials Research Society (1984) has produced a 

review of some of this research. The general goals of 

these site studies are threefold: 

(1) To obtain a detailed understanding of the 

numerous variables affecting the performance 

of each of the barriers. For example, a study of 

the sorption of radionuclides during movement through the host rock involves detailed 

knowledge of the radionuclides' rate of release 

from the waste form, rock mineralogy and 

physical properties, vadose and ground water 

velocity, vadose and ground water chemistry, 

state of the radionuclides (dissolved or colloidal and, if dissolved, their valence state), 

nuclide solubility, the relative importance of 

ion exchange, fixation, and other sorption 

mechanisms, and lastly the alteration of each 

of the above by the strong temperature and 

radiation fields expected in a high-level waste 

repository. 

2Vadose waters are those occurring in the unsaturated zone. 

3 

(2) To quantify the observations made for each barrier by appropriate physicochemical models. 

(3) To couple the quantitative models developed for 

each barrier into a megamodel to be used for 

predicting the rate of migration of radionuclides from the site and their concentration in ground and surface waters and in food 

chains over millenia or more (see Tyler and 

others, 1984; Garisto and Lyon, 1984; and 

Ross, 1986, for outlines of such studies). 

All of these goals are formidable, but we restrict our 

discussion to the feasibility of the last goal, long-term 

prediction of the fate of radionuclides in the environment surrounding the waste repository. 

A relatively small, but highly instructive, literature 

exists on prediction in the earth and other natural 

sciences. This literature may be divided into two 

groups: studies that examine the subject from a 

philosophical viewpoint and studies that emphasize 

the pragmatic aspects. A brief review of this 

literature was presented by the author and by N.J. 

Trask in Bredehoeft and others (1978). Study of this 

literature does not lead to much confidence in the 

ability of megamodels (or even of the component 

models for each barrier) to accurately predict the 

behavior of buried toxic wastes even over periods of 

a few millenia. There are three principal reasons for 

this. (1) An empirical data base does not exist with 

which to calibrate the model. Moreover, future 

assembly of such a data base in any reasonable time 

span appears to be out of the question. Calibration 

would require gathering of field information over a 

period long enough to test the processes of solution, 

transport, adsorption, and chemical reaction that are 

postulated in the models. Given the low solubilities 

of proposed waste forms, the accumulation of such 

data in the field would require decades or perhaps 

centuries. Thus, from the nature of the exercise, 

predictions of the transport and fate of these 

materials in the environment apparently always will 

be based on calculations from uncalibrated models. 

(2) The record of prediction in the earth sciencies, including soil mechanics, the oldest quantitative 

branch of earth science, is mixed. Most engineering 

geologic predictions, in any event, are autopsies; 

predictions made before the event are not as common. Papers by Lambe (1973}, Peck (1980}, and 

Leonards (1982) are particularly instructive reviews 

of prediction in the geotechnical sciences. (3) Strong 

philosophical arguments exist for believing that explanation and prediction in the natural sciences are 

not symmetrical; that is, understanding a process 

(hardly an easy undertaking) does not mean that 
prediction is attainable (Bradbury and others, 1983; 

Scriven, 1959; Mayr, 1961; and Simpson, 1970). 

Stated in the simplest of terms, our ability to 

evaluate predictions of the fate of buried toxic wastes 

over millenia, or even centuries, is severely limited by 

our lack of experience. Hence, predictions of the fate 

of toxic wastes, whether generated by complex or by 

simple physicochemical models, must be viewed with 

great caution. Such predictions involve conditions 

considerably more complex than those commonly 

tackled in geotechnical engineering, such as estimations of the settling of a bridge or skyscraper foundation or of the drawdown of water level in a heavily 

stressed aquifer (Konikow and Patten, 1985). The 

task of predicting the long-term effects of buried toxic wastes on the hydrosphere and biosphere is an excellent example of the transscientific issues discussed 

by Weinberg (1985). As succinctly stated by him 

(1985, p. 60): 

Science deals with regularities in our experience; art deals with 

singularities. It is no wonder that science tends to lose its predictive 

or even explanatory power when the phenomena it deals with are 

singular, irreproducible, and one of a kind-in other words, rare. 

Although science can often analyze a rare event after the fact- for 

example, the extinction of dinosaurs during the CretaceousTertiary period following the presumed collision of the earth and 

an asteroid-it has great difficulty predicting when such an uncommon event will occur. 

What then are we to do? Certainly, process studies 

and modeling efforts related to understanding the 

fate of buried wastes must go forward, because such 

efforts frequently identify the weakest links in our 

knowledge of a system and can lead also to an early 

disqualification of marginal sites proposed for waste 

disposal. But, another endeavor is of equal importance. Synthesis of the archaeological record of 

man's past use of the unsaturated zone for the preservation of objects can provide an invaluable empirical 

data base pertinent to the transscientific problem of 

toxic waste disposal. 

POTENTIAL APPLICATIONS OF 

ARCHAEOLOGY TO TOXIC-WASTE DISPOSAL 

Archaeological science can contribute meaningfully to an evaluation of sites for toxic-waste disposal in 

three ways: (1) by addressing the general efficacy of 

unsaturated zones as environments suitable for 

isolating solidified toxic waste from the hydrosphere 

and biosphere over millenia to tens of millenia, (2) by 

addressing the issue of future human intrusion, and 

(3) by identifying durable, natural, and manmade objects suitable for. encapsulation of wastes or for use 

4 

as warning markers. The last two topics also have application to the disposal of solidified toxic wastes 

below the water table. The first topic- of principal 

concern in this paper- applies exclusively to disposal 

of wastes in unsaturated zones. These three topics are 

interrelated, but for convenience they are discussed 

separately here. 

EFFICACY OF THICK UNSATURATED-ZONE 

ENVIRONMENTS FOR ISOLATION OF SOLIDIFIED 

TOXIC WASTES 

The archaeological record of Late Paleolithic man 

(about 40,000-1p,ooo B.C.) is preserved largely in 

caves and rock shelters, whereas the record of 

Neolithic to Iron Age man (about 8000-1000 B.C.) is 

preserved increasingly in manmade structures. A very 

brief outline of this record demonstrates how well 

delicate, as well as durable, objects emplaced in the 

unsaturated zone by our ancestors- or accidentally 

buried in this environment- have survived over 

millenia to tens of millenia. 

Late Paleolithic man probably was unaware that 

the caves that sheltered him would provide preservation of his lifestyle. Such caves, even those in the 

humid zone, have· yielded the oldest and most famous 

archaeological finds (Leakey, 1981), including molded clay bison from the French cave Le Tuc 

d'Audoubert (about 15,000 years old), ivory animal 

statuettes from the German Vogelherd cave (about 

32,000 years old), and the famous ice-age cave art as 

much as 35,000 years old. These caves provided a 

well-drained environment having a relatively constant annual temperature and humidity- conditions 

apparently favorable for preserving artifacts, despite 

the presence of oxidizing conditions and high 

humidity. 

The archaeological record of Neolithic to Iron Age 

man contains numerous examples of preserved 

delicate objects that were buried, intentionally or 

unintentionally, in presently arid and semiarid unsaturated zones, including but not limited to cave environments. A heap of about 2,600 charred horsebean (Vicia faba L.) seeds was found in an ancient 

dwelling at Yiftah'el near Nazareth in Israel. The 

beans date from 6500 to 6000 B.C. and surprisingly 

were not damaged by insects (Kislev, 1985). Tenthousand-year-old wood dowel, cord, and wood batten are reported from Guitarrero Cave in Peru, 

where arid conditions also led to preservation of textiles and domesticated plants (Lynch and others, 

1985). In areas of extreme aridity, such as along the 

coast of Chile, 4,000- to 8,000-year-old mummies 

have been discovered in shallow burial pits (Allison, 
1985). Some of these mummies were preserved 

naturally, whereas others show that the skills of 

mummification were well known to these people 

several thousand years before the earliest known 

Egyptian mummies. 

Next we cite the amazing preservation of the Dead 

Sea scrolls placed in simple clay jars in shallow caves 

nearly 2,000 years ago (Pfeiffer, 1969). Nearby, at 

Masada, in Israel, beautifully preserved cloth, 

leather sandals, plaited hair, food (walnuts, dates, 

grain, and pomegranates), frescoes, and colored 

mosaic stone floors occur within a few meters of the 

. surface; these materials date from about A.D. 70 

(Yadin, 1966). These examples, only a small fraction 

of those known, are cited to demonstrate the amazing preservation of even delicate organic and inorganic objects placed in the unsaturated zone at 

shallow depths and generally without intent of 

preservation on the part of our ancestors. We consider next a few examples of deliberate and elaborate 

attempts by ancient man to preserve objects of importance. 

Wacks and others ( 1981) briefly described several 

examples of the excellent preservation of a variety of 

objects placed within carefully designed structures 

built by the Egyptians, Chinese, and Indians in the 

period 3000 B.C. to A.D. 1000. For example, portions of the funeral barque of Cheops (about 2600 

B.C.), buried in a rectangular pit in limestone and 

tightly sealed by limestone blocks and gypsum, were 

found in excellent condition in 1954; "even a 91 m 

(300 ft.) long rope and remnants of frayed fabric 

were found on the top deck" (Wacks and others, 

1981, p. 9). Although the rock tombs of the New 

Kingdom, including that of Tutankhamen, all were 

ransacked, delicate objects of little value were left 

behind, including robes, sandals, ostrich feathers, 

and painted wall reliefs (Wacks and others, 1981, p. 

51). In contrast, Wacks and others (1981, p. 15) 

reported that some of the objects in the tomb of King 

Tutankhamen had badly deteriorated due to periodic 

percolation of moisture into the tomb. The Chinese 

cave temples at Ch'ien-fo-tung in Kansu Province at 

the edge of the Gobi Desert have yielded a spectacular library of 1 ,000-year-old manuscript rolls, 

silk banners, and paintings on linen or silk gauze 

(Wacks and others, 1981, p. 25). Wacks and others 

reported the climate of Ch'ien-fo-tung to be similar 

to that of northern Nevada. In contrast, they found 

that preservation of objects was generally poor in Indian temples constructed in the basaltic Deccan 

Traps because of water seepage and structural 

weakness (Wacks and others, 1981, p. 46); these 

5 

structures are all located in presently humid climates. 

On the basis of their brief review of these and other 

"time-tested underground structures," Wacks and 

others (1981, p. 54) concluded, as had hydrogeologists before them (Winograd, 1972, 1974), that 

solidified low-level radioactive wastes might be safely 

emplaced in a "rock-hewn waste complex" within a 

thick arid unsaturated zone, provided special attention were given to prevent future human intrusion. 

Although not strictly in the realm of archaeology, 

evidence of remarkable preservation of late 

Pleistocene plants is available from paleoecological 

studies. Mummified plant fossils, in 10,000- to 

45,000-year-old packrat middens, have been identified to species level (Spaulding, 1985). Such middens are found in open joint planes, small caves, and 

rock shelters throughout the arid and semiarid portions of the Southwestern United States. Although 

only marginally s.beltered, the plants constituting the 

middens survived the relatively wetter climates of the 

late Pleistocene (Spaulding, 1985). 

On the basis of the above cursory examination of 

the archaeological record, it appears that a detailed 

synthesis of this record- with special reference to the 

past and present physical setting of each site- can 

provide us with qualitative, yet highly pertinent, 

analogs of the likely long-term fate of solidified toxic 

wastes buried in unsaturated zone environments. 

Such a synthesis would seek to identify not only 

durable objects that have survived the tests of time 

but also delicate ones. It would attempt to unravel 

the features of the physical environment that led to 

excellent preservation of parchment in one cave but 

permitted poor preservation in an adjacent cave. It 

would attempt to relate preservation of delicate objects to the original and subsequent climates, as well 

as to the geomorphic and hydrogeologic setting of 

sites. The objective of such a synthesis would be no 

less than an attempt to understand the physical, 

chemical, and biological factors leading to preservation of fragile, as well as durable, objects buried in 

arid to semiarid (and even subhumid) unsaturated 

zones by Late Paleolithic to Iron Age man. 

Arguments based on analogy with the archaeological record, however, contain serious problems. First, past climatic conditions at archaeological 

sites cannot easily be determined and probably differed from present conditions. Second, the 

hydrogeologic setting of the better studied archaeological sites are unlikely to match exactly those 

of any unsaturated zone site currently being used or 

being evaluated for receipt of toxic wastes. Third, 

unlike wastes in a high-level radioactive waste 
repository, archaeological remains were never subject to a heat pulse of several hundreds of degrees 

centrigrade nor to intense radiation fields. 3 Lastly, 

archaeological records, like stratigraphic records, are 

incomplete. (See Ager, 1981, for a pertinent discussion of the incompleteness of stratigraphic and, by 

analogy, of archaeological records.) Thus the archaeological record may be biased strongly toward 

successful preservation, the unsuccessful ones having 

left no exciting finds to be described. Nevertheless, 

the large number of unsaturated-zone archaeological 

sites, their occurrence in Holocene and Pleistocene 

climates ranging from arid to humid, and the great 

variety of materials buried in them should permit us 

to glean a wealth of qualitative to semiquantitative 

information bearing on the preservation and relative 

weathering of materials in unsaturated-zone environments over millenia to tens of millenia. Such a 

synthesis can provide an independent evaluation of 

the efficacy of the unsaturated zone under what can 

be viewed only as worst-case conditions; that is, early 

man's burial of unshielded objects at shallow depths 

or his subsequent engineered emplacement of 

precious objects that invited repeated entry into his 

structures by thieves. In contrast, solidified toxic 

wastes of low solubility presumably will be emplaced 

in the unsaturated zone at depths of tens to hundreds 

of meters, will be encapsulated in low-solubility containers, and will be placed in burial chambers designed to conduct vadose water around the waste 

containers (Winograd, 1974, 1981; Roseboom, 

1983). 

The proposed synthesis of the archaeological 

record admittedly is likely to yield only qualitative information regarding the expected fate of materials 

buried in the unsaturated zone over millenia. Yet 

such a synthesis can constitute an invaluable supplement to computer-generated predictions that, 

although quantitative, cannot be evaluated in the 

absence of an empirical data base. 

A second major benefit may be derived from a 

broad examination of the archaeological record; 

namely, providing the public and the courts with a 

readily understood basis for waste disposal in arid 

unsaturated zones. Public perception and acceptance 

are critical to any successful waste disposal program. 

Yet, the ability of the public and of the legal com-· 

3

Aithough temperatures of 100 to several hundred degrees centigrade still 

appear in the high-level radioactive waste literature, current thinking 

(Bredehoeft and others, 1978; Swedish Nuclear Fuel Supply Co., 1983) 

favors keeping the temperatures well below 100 oc to reduce anticipated 

thermomechanical problems in repository construction and long-term performance. For nonradioactive toxic wastes, elevated temperatures and radiation would not detract from analogies with the archaeological record. 

6 

munity to understand the results of interdisciplinary 

computer models- however well accepted they may 

be in the scientific community- probably is limited. 

And, in all likelihood, the scientific community will 

not be unanimous about the suitability of any single 

model- a not unexpected occurrence in view of the 

transscientific nature of the problem and a situation 

unlikely to lead to scientific credibility with the 

public. On the other hand, the public and the courts 

are likely to understand more readily a qualitative 

but strong analog approach, which a detailed examination of the archaeological record can provide. 

The public can nearly touch or see the archaeological 

record and therefore may find it more credible than 

computer-generated numbers of perceived mysterious origin. At the same time, the archaeological 

analog explicitly acknowledges one of the most 

serious reservations about toxic-waste disposal, 

especially shallow (less than 50-m-depth) disposal; 

namely, the potential for intrusion by our unaware 

descendants (see the section "Future Human Intrusion into Toxic-Waste Burial Sites"). 

In summary, the archaeological record examined 

does, in general, sustain the preliminary favorable 

conclusions of earth scientists regarding the utility of 

arid and semiarid unsaturated zones for safe burial 

of solidified toxic wastes. This record provides an invaluable, although qualitative, supplement to the 

quantitative, but untestable, computer-generated 

predictions of the long-term effects of buried wastes 

on the hydrosphere and biosphere. Once the transscientific nature of the toxic-waste disposal problem 

is understood, the qualitative conclusions derivable 

from the archaeological record may suffice to convince the public that solidified toxic waste can be 

safely isolated from the environment by burial in 

carefully chosen thick unsaturated zones. Certainly 

modern man should be able to equal and improve. 

upon the practices of his ancestors in his attempt to 

isolate solidified toxic wastes from the environment 

for millenia to tens of millenia. 

A detailed synthesis of the archaeological 

record- done by archaeologists and Quaternary 

geologists with toxic-waste disposal in mind-is 

needed to verify the generally favorable prognosis 

presented herein concerning the long-term isolation 

of solidified toxic wastes buried at depths of tens of 

meters in thick unsaturated zones of arid regions. 

FUTURE HUMAN INTRUSION INTO TOXIC·WASTE 

BURIAL SITES 

The potential for future human intrusion into 

toxic-waste burial sites has been of major concern to 
advocates of geologic disposal of radioactive wastes 

for more than a decade (Weinberg, 1972). Winograd 

(1981, p. 1462) explicitly acknowledged that of all the 

technical issues involved in an evaluation of thick unsaturated zones as toxic-waste repositories, "the matter of future human intrusion is the crucial unresolved and perhaps unresolvable issue." Wacks and 

others (1981) also were greatly concerned with intrusion. They stated (1981, p. 15), "If the analogy between the Egyptian royal tombs and the modern 

nuclear burial ground is correct, simple thievery and 

vandalism may be more of a threat to the repository 

than natural phenomena such as earthquakes and 

floods." A site chosen for waste burial must not be 

associated with known ore deposits or aquifers. 

Given these obvious exclusions, how can we prevent 

future discovery of, intrusion into, and perhaps even 

use of the wastes by our unaware descendents? Archaeologists began to address this matter a few years 

ago (see, for example, papers by Cameron (1981 ); 

Kaplan (1982); and Battelle Memorial Institute 

(1984)). Topics studied included the geometric placement of warning markers, the languages and symbols 

to be used on the markers, and the endurance or 

physical integrity of marker materials over millenia. 

It can be argued that warning markers exterior to a 

repository will ultimately invite vandalism (and 

possibly intrusion) after institutional control of a site 

is lost and, therefore, that such markers may prove to 

be counterproductive. In contrast, a series of warning markers within the passages leading to the burial 

site or repository appear essential to warn our 

unaware descendents of potential danger in the case 

of intrusion. Additional debate on the wisdom of external markers appears in order. 

The matter of the physical integrity, over millenia, 

of materials used for warning markers is clearly part 

of a third broad area in which archaeology can contribute significantly to solving the problem of toxicwaste disposal. 

IDENTIFICATION OF DURABLE NATURAL AND 

MANMADE MATERIALS 

A major research effort sponsored by the U.S. 

Department of Energy and its predecessors, the 

Energy Research Development Administration and 

the Atomic Energy Commission, during the 1960's 

and 1970's and continuing today, involves the identification of the best types of glass into which 

7 

reprocessed nuclear wastes can be incorporated. 4 

Sought was a glass having very low solubility that 

would resist devitrification for millenia even when 

subjected to temperatures of several hundred degrees 

centigrade. This research, which also includes evaluation of synthetic rock, has spawned a large literature. 

The Materials Research Society devotes a number of 

symposia to this topic at its annual meetings, with the 

results published annually in the book series "Scientific Basis for Nuclear Waste Management" 

(1978-84). Relatively little attention, however, has 

been given to using the state of preservation of dated 

manmade glasses and ceramics, from the archaeological record, as clues to selection of durable 

materials for waste containment. Notable exceptions 

are the reconnaissance studies of Kaplan (1980) and 

Kaplan and Mendell (1982), which contrast the state 

of preservation of glasses of varying ages and from 

different climates, and the work of Roy and Langton 

(1983), who studied the characteristics of ancient 

mortars and plasters dating to 5500 B.C. Further, the 

geologic literature has not been fully used by wastedisposal technologists for clues regarding rates of 

weathering of natural glass and selected rock types. 

Such literature presently exists (Friedman and Long, 

1976; Steen-Mcintyre, 1975; and Colman and Pierce, 

1981). 

Clearly archaeologists, materials scientists, and 

Quaternary geologists should jointly study the extent 

of weathering of durable natural and manmade 

materials as a function of age, climate, geomorphichydrologic setting, and burial environment 

(mausolea, soil zone, colluvium, cave, rock shelter, 

tunnel, and so on). Additionally, detailed petrologic 

and geochemical studies might reveal the amounts 

and perhaps even rates of leaching of selected 

elements from dated rocks, minerals, and manmade 

objects buried in unsaturated (or saturated) zone environments over time frames pertinent to the isolation of toxic wastes. 5 Such information would be of 

immediate interest to waste disposal technologists for 

two purposes: (1) identification of new materials into 

which toxic wastes might be incorporated (via solid 

solution) or encapsulated (that is, used to surround 

4Aithough the disposal of spent fuel, rather than a glass waste form, has 

received major attention in the past 4 to 5 years, spent fuel may be placed 

within a waste package, the design of which can benefit from the considerations raised herein. More importantly, we are looking for time-proven 

materials for the encapsulation of a variety of toxic wastes. 

5For example, a study contrasting the weathering of an inclined vitrophere 

below and above the water table at a single location could provide a wealth 

of information concerning relative leaching of selected elements in these two 

adjacent, but hydrologically different, environments. 
the waste, forming the so-called waste package) and 

(2) selection of durable rocks for fabrication into 

monoliths capable of marking disposal sites for 

millenia. 

SUMMARY 

A "defense in depth" approach is being used in 

evaluating several sites for the disposal of high-level 

radioactive wastes. We hope the same approach will 

be used in selection of new sites for land disposal of 

the most toxic nonradiogenic wastes. The results of 

laboratory and short-term field experiments on the 

multiple barriers at each site will be used, via interdisciplinary mathematical models, to predict the fate 

of buried wastes for millenia and longer. Such 

analyses are justifiable and challenging, but their 

results must be used with extreme caution in view of 

the limitations in geologic prediction of even far 

simpler systems. Clearly, the task of predicting the 

effects of buried toxic wastes on the environment is a 

transscientific one. Yet, the Late Paleolithic to Iron 

Age record of man's inadvertent or intentional use of 

the unsaturated zone for preservation of a large 

variety of objects can serve as an invaluable analog 

of the likely fate of solidified toxic wastes buried in 

arid and semiarid environments. The archaeological 

record is incomplete and qualitative, and its 

transference to waste disposal is subject to the limitations of all arguments by analogy. Nevertheless, it 

provides a real data set upon which to formulate an 

independent and favorable appraisal of the general 

ability of thick unsaturated zones in arid regions to 

isolate solidified toxic wastes from the hydrosphere 

and biosphere for millenia and beyond. Moreover, 

such an appraisal probably can be comprehended far 

more easily by the public and by the courts than the 

numerical output of sophisticated interdisciplinary 

models of the fate of buried toxic waste. Archaeological science can make substantial contributions also to the related important matters of preventing future human intrusion into toxic-waste 

burial sites, choice of solids in which toxic wastes can 

be incorporated or encapsulated, and choice of rocks 

from which durable warning markers can be constructed. 

Archaeologists can contribute substantially to 

evaluation of arid and semiarid unsaturated zone 

sites proposed for the disposal of solidified toxic 

wastes. The involvement of archaeologists in such 

studies, together with earth scientists, chemical 

engineers, and other scientists, appears mandatory. 

8 

ACKNOWLEDGMENTS 

I thank E-an Zen and Newell J. Trask for informal 

reviews of an early draft and Gordon B. Bennett, 

George A. Dinwiddie, Curtis E. Larsen, James R. 

Rollo, and E-an Zen for helpful suggestions pertinent 

to the final draft. This paper is an outgrowth of talks 

given in January 1984 and January 1986 at University 

of Arizona workshops on the physics and chemistry 

of contaminant transport through the unsaturated 

zone. I thank Professor James G. McCray for calling 

my attention, during the first workshop, to an important paper by Wacks and others ( 1981) that clearly 

recognized the potential utility of archaeology in 

selecting sites for the disposal of low-level radioactive 

wastes. 

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