Looking back at Love Canal Results and conclusions of EPA's investigm'on
John Deegan, Jr. University of Northern Iowa Cedar Falls, Iowa 50614
In the first part of this series (ES&T April 1987,pp. 328-31), it was pointed out that the methods and conclusions of EPA's Love Canal Study were the subject of some controversy in the environmental community (I, 2). Others defended the agency's approaches and methods (3). wrt 2 makes no attempt to resolve the controversy; its purpose is to present the results and conclusions of the Love Canal Study. HYclrogeorogy According to geological data and EPA field studies,bedrock in the vicinity of Love Canal is a part of the Lockport dolomite formation, a unit typically encounted 20-45 ft below the Land surface. The thickness of this formation ranges from 160 ft to 180 ft. Throughout the general study area, the Lockport dolomite is overlain by a deposit of l-Z@ft-thick glacial till. This layer's coefficient of permeability, K, is low (IC = lW7 c d s ) . The glacial till, in turn, is covered by layers of lacustrine d e p i t s (sediment deposited when the land was covered with lake water) of clay, silt, and fine sand, approximately 6-29 ft thick. Its permeability is between l@*d s and le7d s . The lacustrine deposits are overlain by silty sand, clayey silt, and other ffi materials, ranging froma few inches to about 3 ft thick. This layer's permeability is than that of the UnderlvinE -mater _ -claw (IC 2 10-5 d s ) . Hvdrolonical data and EPA field studies ha& shown that the h k p o r t dolomite is not a homogeneous aquifer; it contains distinct water-bearing zones, primarily in the upper portion of the formation, which is highly permeable. The bedrock aquifer near Love Canal is artesian and is confined below by Rochester shale and above by the glacial till. Groundwater moves through ~
001383Bw87/~21-0421$01.5~0B 1987 American Chemical Society
Envimn. Sci. Technol., Vol. 21, NO. 5,1987 421
the Lockport dolomite generally from the north to the southwest. The uncomlidated overburden materials are not significant sou~cesof water for the area, and no hydraulic connection between the overburden and bedrock was found. Because of the low permeabiity and heterogeneous nature of the overburden, groundwater movement in the UILConfined aquifw of the overburden (also hown as the shallow system) generally is slow, except in small areas of more permeable material. Shallow-system groundwater movement generally is from the north to the west-southwest. On the basis of these findings, it was inferred that unless the glacial till was breached during excavation, no contamination of the bedrock aquifer directly attributable to Love Canal was likely contaminated groundwater in the shallow system likely would have been confined to the Canal Area be cause of the generally low permeabiity of the uncwlidated materials. The tendency of the clay to adsorb the organic materials depmited in Love Canal and the encircling of the landfii with storm and sanitary sewer line syst e m (Which iocreasediscontinuitiesbetween the already s p w , more permable soils) also would have restricted groundwater transport. Localized contaminant movement, however, could have owwred through discominuws, more permeable soil pathways. Because of the same factors,contaminat m directly ascribable to migration fro, L Love Canal probably would have been c o n f d to Ring 1 of the Canal Area and was expected to be greater near the southern portion of the landfi. It was suspected that Love Canal contaminants might be found in local sewer lines, and that evidence of their transport through the sewers over considerable distances from the landfill might be seen. But because the landfi was capped in 1979, it was thought unl i l y that air contamination caused directly by Love Canal wonld be presem in the Declaration Area.
venient way to summarize a great amount of information. In addition, it removes the analytical and statistical
uncertaintiesassociatedwithsubstance-
by-substance comparisons, and it identiiies the paths of environmental transport of contaminants from Love Canal intothemnoundm ' genvironment. Furthermore, because clay adsorbs the organic substances, and because many of these substances are hvdrorhobic. the sum probably serves an accurate indicator of the range of contaminant movement in the m. The results of environmental monitoring illustrated in Figure 1 (the four largest sums are shown) reveal that the prediction of the hydrogeological studies was correct:The contaminated shallow-system groundwater was c o n f i i to areas relatively close to the actual landfd. In particular, clear evidence of the contamination of shallow-system groundwater was found only within Ring I of the Canal Area (outside the area bounded by the containment systern). Moreover, shallow-system groundwater contaminams were found to occur discretely within Ring 1 in conjunction with more permeable soil pathways. For instance. Well 104A Water mnnitnrhg (Fipure 1) was located in a former Figure 1 shows the results from mon- swale near the containment system in a Well 77A itoring certain targeted organic sub lot south of 754 99th h, stanw in gmnndwater samples frmn was located in a h o w n sand lens near 68 shallow-system wells in the Canal the containment system in the back and Declaration areas. The large yard of 775 97th Street, and Well 75A amount of data obtained (more than 134 was located in a former swale near the compounds were monitored) was sum- containment system in the lot at the marized by adding all of the individual southwest corner of 99th Street and concentrations found at a particular site Colvin Boulevard. In general, all down-gmhent (westand using that sum as an indicator of total contamination. ern-southwestern) sampling sites in the Although this approach ignores the Declaration Area were examined for important issues of toxicity to humans evidence of migrating Love Canal conand the differential mobility rate for taminants, and all upgradient sampling each substance monitored, it is a con- sites can be considered analogous to 422 Emimn Scl Technol, MI. 21. No 5,1987
as
control sites. Even though numerons sites were sampled in the Declaration AreaandinRing2oftheCanalArea, however, the monitoring results r e vealed that contaminants were not transported to shallow-system groundwater outside Ring 1 @igure 1). They also were not transported to Ring 2 sites, which nominally were the direct outward extensions of Ring 1 soil transuort d w a v.s .(swales. sand lenses. and
;vet k). The. fourth largest amount of mtamination (Well 32A) was found at a substantial distance (225-300 m) from the lendfill (ikbeyond the distance of likely transport). The sum of organic contaminants found in Well 32A is nearly one. order of madtude lower than -the third largest sum (88 ppb vs. 741 ppb). This contamination did not show evidence of occurring as a result of intervening transport of contaminants and probably was not located down-gradient from the source. Finally, all other sites not specifically identified in Figure I had organic compound concentration sums of less than 88 ppb. Samples from 46 shallow-systern wells (out of the 79 sampled) showed that organic contaminants were present at only trace or lower concentration levels. Figure 2 identifies the five largest of the Concentrations of the more than 134 targeted organic substances monitored in groundwater obtained from bedrock wells installed in the Canal and Declaration areas. The summing pmcedure applied to the data indicates that the observed low-level organic conwnination found in tedruck groundwater samples was wide spread and occurred randomly; there was no evidence of a plume emanating from Love Canal. This result is expected on the basis of the hydrogeology
studies. For example, bedrock groundwater contamination is found in the Declaration Area at sites located u p gradient (north, east, and immediately northwest) of the landfdl, and upgradient contamination is found at considerable distances from Love Canal. Samples from all of the bedrock monitoring wells located in the Canal Area had summed organic concentrations of less than 100 ppb (bedrock monitoring wells located in the Canal Area encircle the landfill). Because of the south-southwesterly direction of groundwater movement in the Lockport dolomite near Love Canal and because of the lack of clear evidence of a plume of contamination in the bedrock area originating in the Canal Area, it is likely that the contamination found in the aquifer was not directly related to the migration of contaminants from Love Canal. Also, because monitoring results at down-gradient sites are the only indicators of the likely migration of contaminants from a source of groundwater contamination, all upgradient bedrock aquifer monitoring sites located within the Declaration Area should be considered analogous to control sites. A total of 21 wells (of the 57 sampled) exhibited contamination at only trace or lower concentrations.
Soil monitoring Figure 3 depicts the results from the soil monitoring program, as represented by the summed concentrations of the more than 134 targeted organic substances monitored in soils sampled at 136 Canal and Declaration area sites (the eight largest sums are identified). The data suggest that soil contamination directly attributable to the migration of contaminants from Love Canal was confined to the Canal Area. This contamination corresponded to the patterns found for shallow-system groundwater contamination, and it occurred in a manner predicted by the hydrogeological studies. Evidence of soil contamination attributable to the migration of contaminants from Love Canal could be found selectively near certain Ring 1 residences that had been subjected to the overland flow of contaminants from the landfill before remedial action began at the site. These were residences that had been constructed in the vicinity of more permeable soil pathways from the landfill. The monitoring data revealed substantial soil contamination at Ring 1 site 11018 (741 97th Street), which was the soil sampling site located closest to the known sand lens on the 97th Street side of Love Canal. The data also indicated the presence of Love Canal contaminants at Ring 1 site 11005 (684 99th Street), located in a major swale that
formerly had lain across Love Canal. The absence of compelling evidence that soil contamination emanated from Love Canal toward the other soil sampling sites shown in Figure 3 suggests that the observed contamination was not caused by the natural migration of contaminants from the landfill. It is more likely that soil contamination found in widely separated sites throughout the Declaration Area came from other sources, such as fill materials that may have been contaminated with industrial wastes. No pattern of soil contamination in this area could be found to correspond to the shallow-systern groundwater gradient. It is highly unlikely that the organic substances disposed of in Love Canal, many of which were hydrophobic, could migrate turally over substantial distances from the landfill. This is ascribable to the very slow rate of movement of the shallowsystem groundwater and solution-phase
contaminants as well as to the sorption of organic Love Canal wastes by clay (sorbed-phasecontamination of soil). Moreover, the streets and sewer lines that encircle the landfill served to increase discontinuities in the naturally sparse preferential soil transport pathways and decreased the likelihood of distant natural migration of contaminants from the landfdl. That is, the more permeable soil materials were deposited randomly and in small quantities, like sediments in glacial lakes. Hence, the preferential (more permeable) pathways occurred sparsely. The digging of sewer trenches through these materials severed them, so their discontinuity has been increased. Only isolated areas of soil contamination were found in the Declaration Area, and these often were located substantial distances from Love Canal. Also, nearly all of the topsoil in the Declaration Area consists of fill. and
FIGURE 2
Sums of wmmtdcm of organk compounds in bedrock welk
FIGURE 3
Sums of concanhationsof argank compounds in soli /C
A-SitellO18 15337~:8--sflsou)25 3120ppb.C-SteO1011 3 B 6 p p b E-SiRWSOl 2938ppb: E-Sits W18: 2% ppb: F-Sine 1,005,2413 wb G-Sie 08035. i4US ppb: H-Site 07002. i3ol p0b
Environ. ki.Technol.. Val. 21. NO.5. 1987 423
many residents suspected that the fffl materials may have been contaminated with indusaial wastes. Only 10 of the 171 soil sampling sites had organic contaminants present at trace or lower concentrations. The objective of the EPA sumpmonitoring program was to provide indirect additional evidence of Love Canal-E laced environmental transport of contaminants through shallow-system groundwater and near surface mil. 11 was reasoned that such evidence would be obtained wherever Love Canal-related contamination was present in samples of basement sump w a r s or sediments. Figure 4 illustrates the results from monitoring more than 134 targeted substances in water samples c o l l d from residential sumps in the Canal and Declaration areas (the six largest sums are identified). The results of the monitoring program reveal a panern of environmental contamination consistent with that of the hydrogaological Studies. They also compand closely to findings in shallow-system groundwater and soil (Figure 4). Much of the sump water contamination found at Love Canal occurred in those Ring 1 residences (often situated in wet areas) that were suspetted of having been subjected to the overland Bow of contaminants from the lanflffl before remediation. This contamination also was found in those Ring 1 residences that had been constructed in the vicinity of more permeable soil transport pathways that conveyed contaminants directly from the landfill. It is important to note that all the Canal Area sump had been disconnected in 1979, at least one year before EPA monitoring began. Canal Area sump water contamination was found at the following sites, listed in decreasing order of summed organic substances: site 11071 at 779 97th Street, site 11070 at 783 97th Street, site 11072 at 771 97th Street, site 11021at 476 99th saeet. site 11073 at 703 97th Street, and site' 11005 at 684 99th street. The three most highly contaminated samples of sump water were obtained from those Ring 1 residences located nearest the sand lens on the western side of Love Canal, south of Wheatfield Avenue; near monitoring well 77A, installed in the sand lens located in the back yard of the Ring 1 residence at 775 97th street, and near the Ring 1 soil sampling site 11012 at 741 97th Street, which was located closest to the same sand lens. In addition, evidence of both sump water contamination and soil contamination was identified at Ring 1 site 11005 located at 684 99th Street, which was previously identified as being situated in the major swale that 424 Envimn. Sci. Technol., Vol. 21, No. 5, 1987
formerly had lain across Love Canal. A
Because the landfill had been capped in
total of only 11 sump water sites (of the
1979, no abundant surface source of Love Canal contaminants was generally available for widespread airborne transport into the surrounding environment. The below-ground transport of contaminants that could volatilize and infdtrate basemnt walls was found to be localized and highly selective. Statistical analys& conducted on the extensive air-monitorine data collected revealed no significant-ictional relationships between the observed concentration levels and such factors as distance from Love Canal, wet-area or dry-area residences, proximity to a former swale, diurnal or nocturnal sampling, or the sampling date. Substantially elevated levels of Love Canal-related air contaminants were found in certain Ring 1 residences, however, especially those that were near preferential environmental transport pathways and those that displayed other evidence of environmental contamination. 'lb illustrate the consistency of the results obtained from the air-monitoring study conducted at the 61 Canal and Declaration area sites, three specific examples of graphically s u m m a r i d data are presented. In Figures 5a-5c, the median concentration values of all measurements taken in living areas for benzene, toluene, and 1,1,2,2-tetrachloroethylene (respectively) are displayed for each site that was monitored routinely For comparison, several of the highest medii concentration levels found are identified. No patterns of air contamination were found to reflect directly the transport of the most frequently detected organic compounds found in air samples. Rather, these substances were found to be ubiquitous in the greater Niagara Falls area. Moreover, even the relative frequency and concentration levels at
54 sites sampled) had organic contaminants present at only trace or lower concentrations. It should be noted that before completion of the Love Canal containment system in 1979, Canal Area basement sumps discharged into the local storm sew& Lines on 97th and 99th Streets. The likelv cotlsepuences on the distant transport-of Lovi Canal contaminants into the surrounding environment are obvious. They are discussed in &!ail in Volume I of the EPA report (4).
Airmonitoring The purpose of the air-monit&g program conducted at Love Canal was to determine the spatial and temporal variation of airborne contaminants within the Declaration Area caused by those contaminants migrating from the former canal. EPA targeted 50 substances for monitoring and selected a total of 55 Declaration Area residences (all voluntarily and continuously unoccupied) and six Canal Area residences for extensive air sampling. In addition, the agency conducted a number of specialized air-monitoring stndies to determine the ambient environmental transport of air pollutants throughout the greater Niagara Falls area, the relationship between basement air qnality and sump contamination, the effects of household activities on indoor air pollution levels, and daytime and nighttime variability in air pollution levels. The individuaJ results from these specialized studies are not considered here. The results obtained from the airmonitoring program were found to conform closely to the results of the other monitoring programs and to the inferences of the hydrngeological studies.
which these three substances were detected in air samples must be interpreted with caution, because their occurrence is associated with known contamination of the medium on which the samples have been collected.
Contamination spread inhibited In any review of the monitoring results, it is important to note that not all shallow-system groundwater, soil, sump water, and air sampling sites were coincident, or even contiguous. Therefore, it is reasonable to combine and interpolate the results from the monitoring studies to obtain a more comprehensive picture of environmental contamination attributable to Love Canal. First, the hydrogeologic characteristics of the site largely inhibited transport of Love Canal wastes into the surrounding environment. Moreover, the streets, sewer lines, and barrier containment system that encircle the landfill further reduced the likelihood of Love Canal wastes migrating beyond Ring 1 of the Canal Area. The multimedia environmental monitoring results, considered as a whole, offer strong corroboration of the findings and implications of the hydrogeologiccharacteristics of the site. Specifically, they confirm that widespread, distant transport of Love Canal wastes into the Declaration Area did not occur. These monitoring results also demonstrated that within the Canal Area, movement of wastes was largely restricted to the vicinity of specific Ring 1 residences: in the northeast portion of Ring 1, located near the major swale that formerly had lain across the landfill; in the southeast portion of Ring 1 (south of Wheatfield Avenue), to residences located in low-lying wet areas; and in the southwest portion of Ring 1 (south of Wheatfield Avenue), to residences located near the sand lens or in low-lying wet areas. Because of the clear lack of environmental monitoring evidence (including extensive New York State monitoring data collected before 1980) demonstrating the migration of Love Canal wastes into the Declaration Area-in fact, because of the limited likelihood that such migration should have occurred at allthe reasonable conclusion was that there was no environmental basis on which to find the Declaration Area uninhabitable as a result of the natural migration of chemical wastes from Love Canal. Finally, closure of Ring 2 of the Canal Area provides a certain margin of safety to public health, and that area should remain closed. The severity of environmental contamination found selectively in Ring 1 was far greater than had previously been thought; fortu-
(b) Toluene
(c) 1,1,2,2-Tehachlomethylene
Environ. Sci. Technol.. Vol. 21, No. 5. 1987 425
Radon and Its Decay Products Occurrence,Properties, an Heatth ,-ffE
H
ere's a timeb new book that br together reports by leading exr on a toDic of increasina concerr the r gn weis of radon oe i g f o m awr a r The realm on of the wten widespread effects of radon and its < products on lung cancer rates has tx growing in the radon research comm for almost a decade. This book offen first comprehensive look at recent fir in the field of radon-related research a strong emphasis on the fundameni chemical questions involved. You'll fin erage on key topics in the recent rad bate, including: 0 0 0
mmgation m e m m heath e f f e N ccturrence measurement methcds chemical pmpemes
You'll read reports on specific topics,
as: 0
indmr r%n due to potable water and ylii indmr radon levek in the United States ani
cwntner
e mmpamon of r%n measurement devres e f f ~ %of radon on & m a l proper% of i air 0 critique of arrent lung dmimetry rnOdek I
PWV e w w
Because of its broad scope. internatii perspxhve. and current relevance. t book is an invaluable treatise on the problem. Philip K. Hopke. Editor, Uniwnity of Ill Developed from a symposium spansore the Divisions of Envimnmentai Chemist Nuciear Chemistry and Technologof tl Amencan Chemical society ACS Svmwrium Series No. 331 586 pages (1987) Clothbound LC 86-32042 ISBN 0-8412-1015 US 8. Canada $89.95 Export $107. Order h m : Anmicaan Chemical &My Distribution OKue Dept. 40 1155 Weenth St.N.W. Washington. Dc 20336
w W m U mEE
800-424-67
and use your c r d t cardl
420 Environ. Sci. Technol.. Voi. 21. No. 5, 1987
nately, however, environmental contamination throughout this area was not as extensive as had been feared.
For the future Many lessons in environmental monitoring and site assessment can be learned from EPA's experiences at Love Canal. A number of factors merit consideration should the need ever arise to make similar assessments. It must be acknowledged that it is impossible to make an absolutely certain environmental assessment of the habitability of a site. All of the uncertainties associated with environmental sampling, analytical chemistry methodologies (including quality assurance and quality control), human health effects of exposures to substances environmentally available at a site, cost, time, human emotions, and political imperatives conspire to prevent the accomplishment of this task. Therefore, an assessment strategy that maximizes the protection of public health and the environment should be devised, and this method must provide a balance for the remaining competing factors in a reasonable fashion. The environmental assessment of a site should be performed on the basis of integrated, sequential studies. It should include a comprehensive hydrogeological investigation of the site to determine the potential for contaminant migration and the likely direction of contaminant movement. Multimedia environmental monitoring studies should also be a part of any assessment to identify site-specific contaminants and to determine the likely extent of contaminant movement from the site. Multimedia monitoring results should be integrated to assess the consistency of their findings, and these results should be correlated with the results of hydrogeological investigations to assess the consistency of the findings. Multimedia environmentd monitoring studies should be designed to maximize the likelihood of achieving a deterministic rather than a statistically inferential identification of contaminants migrating from the site. Field sampling in all media should be performed as close to the source as practicable and should then be directed outward from the source on the basis of analytical determinations of targeted chemicals in the samples traced directly to the source. This process should be conducted iteratively (as opposed to cross-sectionally); analytical results should be obtained from adjacent sampling sites before sampling is done at more distant sites. One approach is to sample more distant (outward) locations until targeted substances are no longer detected in the
sample, or at least until two consecutive samples show no significant change in concentration levels. Regardless of whether more distant or more proximate sampling is selected, field sampling should ensure that the gradients of all contamination plumes, in all media, are identified and traced directly from the source to their ambient levels or boundaries of nondetection. Finally, because no standards or bases exist to permit absolute environmental assessment of the habitability of an area, if an assessment is to be performed, only a relative assessment of the habitability of the area can be made. At least three conditions must be met. It must be demonstrated with reasonable certainty that the a r x in question is outside the sphere of influence of a particular source of contaminants. The wurce must be contained naturally or artificially to prevent human exposure. The source must be monitored perpetually to verify that the contaminants remain contained. Once these conditions are met, it follows that contaminants ftom the source are not likely to be available in the area of interest. In that event, human exposure to substances migrating from the source probably will not occur, and there will be no environmental basis to judge the area uninhabitable. References ( I ) S i l k g e l d , E. K. Testimony presented before the Subcommittee on Commerce, ltansportation, and Tourism. U.S. House of Rep resentatives; GPO Serial No. 97-197; Washington, D.C., 1982; pp. 76-100. (2) Stoline. M.R.; C w k , R. J . Am. Star. 1986.40. 112-77. (3) Deegan 1. Supplementary statement prepared for the Subcommittee on Commerce, 'ltansportation, and Tourism, U.S. House of Representatives; GPO Serial No. 97.197; Washington. D.C.. 1982; pp. 109-153. (4)Environmental Moniroring at Love Conol, EPA MM/4-82-030a, NTlS PB82-237330; EPA: Washington, D.C.. 1982; Vol. 1.
John Deegan, JI., is dean of rhe College of Social and Behavioral Sciences ar rhe University of Northern Iowa. He sewed as projen coordinaror for the 1980 EPA Love Canal environmental moniroring srudies and was the primnry aurhor of a threevolume report published in 1982.
7 l i s is the second part
of a two-parr series.
