A careful study of 50 landfills in 1977 concluded that 43 out of 50 (86%) had contaminated underground water supplies beyond the boundaries of the landfill. At the other 7 sites, off-site contamination was measured but could not be attributed to the landfills by the strict criteria used in the study. In other words, the study of 50 landfills found groundwater pollution at all 50 sites, but the contamination could be definitely traced to the landfills in only 43 cases (86%).

The study was conducted by Geraghty & Miller of Port Washington, NY, one of the nation's leading hydrology consulting firms, under contract to EPA (U.S. Environmental Protection Agency). They looked at 122 sites in 15 states and finally selected 50 sites in 11 states for careful evaluation. They studied 7 in Wisconsin, 6 in Illinois, 5 in Indiana, 5 in Michigan, 2 in Pennsylvania, 5 in New York, 9 in New Jersey, 3 in Connecticut, 5 in Massachusetts, 2 in New Hampshire, and 1 in Florida.

Criteria for selecting sites were strict: no site was selected if it was already known to be contaminated or if there were reports of bad taste or bad odors from drinking water near the site already; sites were selected to include various geologic settings (various rock and soil types) and various climatic conditions; sites were selected to include different kinds of dumping (landfills and lagoons), and different kinds of wastes. Some of the wastes would be termed "hazardous" today, but many of the wastes involved were not "hazardous" by today's legal definitions and are still allowed in municipal landfills today. Sites had to be at least 3 years old.

The criteria for determining whether a site was contaminating groundwater were strict. (1) Contaminants had to be measured in groundwater beyond the perimeter of the site; (2) the concentration of contaminants downstream of the site had to be greater than the concentration of the same contaminants measured in an uncontaminated background well; (3) all wells used had to be tapping the same aquifer; (4) geologic interpretation of the data by hydrologists had to convince them that the landfills was the source of the contamination.

In 43 out of 50 cases, the landfill was confirmed as the source of contamination. In four other cases, contamination was confirmed, but the area of contamination was so great that sources besides the landfill were also suspected; at three more sites, contamination was found but data could not be gathered from uncontaminated background wells. So contamination was confirmed at all 50 sites, but in 7 cases, the project's criteria could not be met for deciding that the landfill was the culprit.

The term "landfill" was used to mean a dumping ground that accepted garbage, demolition debris, municipal and industrial solid wastes, sludges or liquids. The investigation "concentrated on those landfills with a major component of industrial waste."

Some of the landfills had liners, others did not. Since publishing this study, the EPA has published its opinion several times, that all landfill liners will eventually leak. (See HWN #37.) Thus this study provides important evidence that all landfills, lined or not, all eventually contaminate groundwater. Lined landfills will contaminate groundwater more slowly than unlined landfills, but the long-term effects will be the same: someone's groundwater will become contaminated whenever municipal solid waste or industrial waste or legally hazardous wastes are placed in the ground.

The study makes some interesting points worth remembering about landfills: "The intermixing of inorganic and organic wastes, wastes of high and low pH, and wastes having different physical properties in a common disposal area, may lead to influences on the environment not anticipated from any single waste material." (pg. 7) This is important because landfill liners are selected to be compatible with the wastes that will be placed in a landfill. However, as this statement says, the mixing of wastes in a landfill will produced unanticipated chemical combinations with unpredictable results. A landfill liner selected to withstand attack from chemicals X, Y and Z may not withstand attack from chemicals X and Z in combination, or Y and Z in combination. The more chemicals involved, the greater the number of possible combinations, the more complex the interactions will be, and the less predictable the results become.

The study makes another valuable point: "The wastes that are deposited continue to weather and leach for years." (pg. 8) The chemical interactions within a landfill do not cease when the dumping stops. In the case of inorganic materials (arsenic, lead, chromium and so forth) the duration of the hazard is essentially infinite--toxic metals will never change into anything besides toxic metals. (The Geraghty & Miller study found toxic heavy metals at 49 of the 50 sites and found they contaminated groundwater off-site at 40 of the 50 sites.)

When anyone proposes a new landfill and says that liners are being selected to prevent contamination of the environment, you should ask, (a) How can they possibly predict all the possible combinations of chemicals that will be created inside the landfill, producing new combinations of chemicals that will attack the liners?; and (b) What is the expected duration of the hazard inside the landfill vs. the expected duration of the liners that have been selected?

If the proponents of a landfill project are honest, these questions will force them to admit that they are not able to predict the chemicals that will come in contact with the liner (especially since the chemicals used by industry change from year to year, and an average of 1000 new chemicals go into commercial use each year); and they will be forced to admit that the duration of the hazard (in the case of metals at least) is very great (thousands of years or longer) whereas the expected lifetime of any human-created material (including packed clay liners and all FMLs [flexible membrane liners]) is much shorter than the expected hazard. Leakage is inevitable.

Common sense and available data combine to force a single conclusion: all landfills will eventually leak. Landfill liners may SLOW the release of contaminants into groundwater but they cannot PREVENT it. There is no such thing as a secure landfill.

The Geraghty & Miller study is THE PREVALANCE OF SUBSURFACE MIGRATION OF HAZARDOUS CHEMICAL SUBSTANCES AT SELECTED INDUSTRIAL WASTE LAND DISPOSAL SITES [EPA/530-SW-634] first published by EPA in 1977; sill available from National Technical Information Service [NTIS], Springfield, VA 22161; phone (703) 487-4650; order No. PB 275103; $44.95 plus $3.00 handling.
--Peter Montague, Ph.D.

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