Sources of Soil and Ground Water Contaminants: Hazardous Wastes
This site was created by Gale Famisan, Sarah Grubbs, and Tara Willey
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Pollution of groundwater has become a major problem in the United States. Groundwater flows at a slow rate, through rock and soil formations. The soil contains high levels of carbon dioxide, which dissolves in the groundwater. This turns the groundwater into a weak acid capable of dissolving substances that neutral water cannot. Groundwater, then can dissolve many of the pollutants placed in the earth and carry them downward to contaminate the groundwater that has become so important to the United States. These pollutants originate from hazardous waste disposal in soil.
Congress has defined hazardous wastes as those discarded materials that may threaten human health or the environment when improperly disposed. Hazardous wastes are regulated by a number of federal laws, including the Resource Conservation and Recovery Act (RCRA), the Toxic Substances Control Act (TSCA), the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), and numerous other regulation related specifically to air or water quality. The main one we will concern ourselves with will be RCRA.
| Regulation Title | Year | Purpose |
| National Environmental Policy Act (NEPA) | 1969 (1975a, 1975b) | Provides a national environmental policy and promotes consideration of environmental concerns by federal agencies. |
| Clean Water Act (CWA) | 1972 (1977, 1987, 1988, 1990) | Provides a regulatory focus to rigorous control of toxic waste pollutants protecting surface and ground water quality to maintain "beneficial uses" of water; also includes provision for ocean dumping and solid waste land disposal facilities. |
| Safe Drinking Water Act (SDWA) | 1974 (1986) | Provides national standards for levels of contamination in drinking water, underground injection of hazardous wastes, and for the protection of sole source aquifers. |
| Toxic Substance Control Act (TSCA) | 1976 | Provides testing of chemical substances, old and new, entering the environment and regulates them if necessary. |
| Resource Conservation and Recovery Act (RCRA) | 1976 (1984) | Provides "cradle to grave" control of hazardous wastes by imposing management requirements on generators and transporters of hazardous wastes, and upon owners and operators of treatment, storage, and disposal facilities; also provides a comprehensive regulatory program of underground storage tank systems; mainly applies to active facilities. |
| Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund) | 1980 (1986) | Provides funding and enforcement authority for assessments and remediation of hazardous waste sites, and requires reporting of releases of hazardous chemicals; mainly applies to past abandoned and inactive sites; provides protocol for preparing and responding to discharges of oil and releases of hazardous substances, pollutants and contaminants into or upon navigable waters and adjoining shore lines under the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). |
| Nuclear Waste Policy Act (NWPA) | Provides standards for management and disposal of spent nuclear fuel, high level and transuranic radioactive waste, and uranium and thorium mill tailings. |
RCRA, which was enacted by Congress in 1976, regulates hazardous waste. RCRA's primary goals are to protect human health and the environment from the potential hazards of waste disposal, to conserve energy and natural resources, to reduce the amount of waste generated, and to ensure that wastes are managed in an environmentally sound manner. Wastes that exhibit certain characteristics may be regulated by RCRA. A waste may be considered hazardous if it is ignitable (i.e., burns readily), corrosive, toxic, or reactive (e.g., explosive). In addition to these characteristic wastes, EPA has developed a list of over 500 specific hazardous wastes. Hazardous waste takes many physical forms and may be solid, semi-solid, or even liquid.
The RCRA hazardous waste program regulates commercial businesses as well as federal, state and local government facilities that generate, transport, treat, store, or dispose of hazardous waste. Each of these entities is regulated to ensure proper management of hazardous waste from the moment it is generated until its ultimate disposal or destruction. Many types of businesses generate hazardous waste. Some are small companies that may be located in your community. For example, the following types of businesses typically generate hazardous waste: dry cleaners, auto repair shops, hospitals, exterminators, and photo processing centers. Some hazardous waste generators are larger companies like chemical manufacturers, electroplating companies, and petroleum refineries.
According to USEPA, only 1 out of every 6 generators manage their hazardous waste on site. Most ship their waste off site to be treated, stored or disposed.
Fact:
In, 1995, nearly 20,000 hazardous waste generators produced 279 million tons of hazardous waste regulated by RCRA.
Even the U.S. household contributes to the hazardous waste problem by generating about 10 pounds of hazardous wastes each year. These items include cleaning solvents, paints, motor oil, garden chemicals and other products.
Classification of Hazardous Waste Generators
Large Quantity Generator (LQG) - one that generate at least 1000 kilograms of hazardous waste per month or over 1 kilogram of acutely hazardous waste per month.
Small Quantity Generator (SQG) - one that generates between 100 and 1000 kilograms of hazardous waste per month.
Conditionally exempt small quantity generator (CESQG) - one that generates less than 100 kilograms of hazardous waste per month.
The Major Sources of Hazardous Waste
Industry
Mining
Processing of materials:
· asbestos work
· foundries
· metal finishing works
· timber product processing
· leather tanning and finishing
· rubber processing
· plastics processing
· electroplating
Manufacturing Processes:
· inorganic chemicals manufacturing
· textile mills
· organic chemicals manufacturing
-adhesives
-gum and wood chemicals
-pharmaceuticals
-explosives
-pesticides
· non-ferrous metals manufacturing
· soap and detergent manufacturing
· machinery and mechanical products manufacturing
- aluminum forming
- battery manufacturing
- copper forming
Domestic
Septic tanks and cesspools
Household cleaning chemicals
Home lawn and garden fertilizers and pesticides
Car battery and motor oil disposal
Nonpoint Sources
Agriculture: Runoff and infiltration of:
· fertilizers
· pesticides, fungicides, and herbicides
· manuring
Landfills and surface impoundments
· leachate seepage
· improper hazardous waste disposal
| Types of Hazardous Waste Generated in the United States | |
| Waste Group Generated | Percent of Generators |
| Spent solvents (halogenated/nonhalogenated) | 53.1 |
| Ignitable wastes | 43.4 |
| Corrosive wastes | 33.4 |
| Spilled or discarded commercial chemical products or manufacturing chemical intermediates | 28.8 |
| Extraction toxic wastes | 27.8 |
| Electroplating and coating wastewater treatment sludge and cyanide-bearing solutions | 16.4 |
| Hazardous wastes not listed or regulated by EPA | 12.2 |
| Listed industrial wastes from specific sources | 10.2 |
| Acutely hazardous wastes | 10.2 |
| Reactive wastes | 7.1 |
Non-aqueous phase liquids (NAPLs) are organic liquids that are relatively insoluble in water. NAPLs are able to move as a separate phase through the groundwater since they are not very soluble. Despite their low solubility, NAPLs are soluble enough to contaminate groundwater. Once a NAPL is introduced into a system it leaves a trail of contamination as it seeps into the ground. This trail consists of isolated droplets held by capillary force. These droplets are immobile, but they slowly dissolve into surrounding water.
Light non-aqueous phase liquids (LNAPLs) have densities less than that of water. A few examples of LNAPLs are kerosene, jet fuel, benzene, and toluene. Since LNAPLs are lighter than water they tend to float on the surface of the groundwater. As the water table fluctuates a smear zone is created
Dense non-aqueous phase liquids (DNAPLs) have densities greater than that of water. Trichloroethylene, methylene chloride, trichloroethane, dichlorobenzene are examples of DNAPLs. DNAPLs sink to the bottom of the aquifer, and since they are toxic at low concentrations the entire aquifer is easily contaminated. Because of this, DNAPLs are usually a more serious problem than LNAPLs.
Hazardous wastes and subsurface interfaces depend on the temperature and organic content of the soil. There are two types of interfaces in the subsurface, fluid and fluid, and fluid and solid. The fluid/fluid interfaces may be air/water, air/NAPL, water/NAPL; and the solid/fluid interfaces may be water/soil, air/water/soil, or air/water/soil/NAPL. The partitioning in the subsurface may be estimated by using water solubilities, vapor pressures, Henry's constants, and other partition coefficients.
Sorption is the physical or chemical bonding of a pollutant to a solid surface, such as soil. This is a major factor in controlling the movement of hazardous wastes. The subsurface environment strives to maintain an equilibrium between adsorption and desorption of pollutants.
Hazardous wastes may degrade naturally by photodegradation, biological degradation, and chemical degradation.
Photodegradation is caused by sunlight, and depends on the molecular structure of the pollutant. One type of photodegradation involves light absorption and directly results in a degradation or transformation of the substance. The other type of photodegradation is a process that causes a sensitizer molecule to accelerate the decomposition of the hazardous waste.
Biological degradation results mostly from bacteria. However, many synthetic organics are resistant to biological degradation. These organics are termed refractory compounds.
Chemical degradation leads to the destruction of specific compounds. One type of chemical degradation is hydrolysis, which involves water. The rate of chemical degradation depends on the chemical characteristics of the medium, as well as the physical environment.
Mathematical models may be useful in understanding the fate of hazardous wastes in the subsurface. These models are usually a series of equations integrating reactions and processes occurring in the soil/groundwater system. Mathematical models assume equilibrium and heterogeneous conditions to predict the migration of hazardous wastes.
Triana/ Tennessee River site, Alabama
The Triana/ Tennessee River site is located within the boundaries of a national wildlife refuge and a United States Army installation. From 1947 to 1970, industrial production and disposal of DDT occurred on the site. Approximately 409 tons of DDT and related breakdown products DDD and DDE contaminated the soil and sediments of 11 miles of two tributaries of the Tennessee River. Six hundred residents of nearby towns were threatened by the contamination and bald eagles, 60,000 migratory birds and the habitat of several endangered species were in direct risk of the contamination.
In 1977, government environmental officials issued a fish advisory on the site, thus starting the actions taken to remediate the site. In 1981, EPA proposed that the site be placed on the National Priority List under Superfund, and in 1983, it was listed. In 1984, EPA completed a cleanup plan for the site and remediation activities began in 1986.
Actions taken for remediation of the site included diverting the river to a new channel and containment of contaminated sediments in the old river channel. 150,000 cubic yards of contaminated soil was removed and replaced with 217,000 cubic yards of clean soil and 190,000 cubic yards of rock to fill the old channel. 93% of the contaminated sediments were encapsulated. Cleanup activities were completed in 1991 and monitoring still continues through the end of 1998. The cost of the cleanup is estimated to be $30 million.
The EPA and Olin cleanup site on the Triana/Tennessee River, Alabama.
Radium Chemical site, New York City
The Radium Chemical site spanned across only one-third acre in a light industrial area of New York City. The company stored radium used in cancer treatment from 1951 until the site was abandoned in 1988, when New York State ordered the company to cease operations. Radium on the site was a threat to the 300,000 residents who lived within three miles of the site.
Cleanup actions included removing 10,000 small metal containers with 120 curies of radium, decontamination of the building followed by its demolition, excavation of contaminated soil and removal of the contaminated sewer system. The contaminated materials taken from the site were disposed of at an approved waste disposal site.
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Sierra Club Books: San Francisco, 593 p.
· Gronow, J.R., Schonfield A.N., Jain R.K., 1988, Land Disposal of Hazardous
Waste: Engineering and Environmental Issues. John
Wiley and Sons : New York, 311p.
· Lesage, S., Jackson, R.E., 1992, Groundwater Contamination and Analysis at
Hazardous Waste Sites. Marcel Dekker, Inc.: New York, 545 p.
· Page, G.W., 1997, Contaminated Sites and Environmental Cleanup. Academic Press:
San Diego, 212 p.
· Testa, S.M., 1994, Geological Aspects of Hazardous Waste Management. Lewis
Publishers: Boca Raton, 537 p.
· Tillman, D.A., Rossi, A.J., Vick, K.M., 1989, Incineration of Municipal
and Hazardous Solid Wastes. Academic Press: San Diego, 343 p.
· Wilson, D.J., Clarke, A.N., 1994, Hazardous Waste Site Soil Remediation. Marcel
Dekker, Inc: New York, 567 p.
· Wood, E.F., 1984, Groundwater Contamination from Hazardous Wastes. Prentice-Hall,
Inc.: New Jersey, 163 p.
Please direct any comments or questions to gfamisan@vt.edu, sgrubbs@vt.edu , or kwilley@vt.edu
Faculty Advisor: Naraine Persaud, npers@vt.edu
Copyright © 1998 Naraine Persaud
Last Modified: January 1, 1999
