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A TYPICAL UNDERGROUND INJECTION WELL
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Underground Injection Wells use a technology which injects liquid waste thousands
of feet below the ground in porous formations. The liquid waste is held within the strata by pressure from overlying rocks. Underground injection involves drilling
a well to a geological formation and pumping, or "injecting" waste to displace the native fluids or gases.
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Source: Office of Technology Assessment, Technologies and
Management Strategies for Hazardous Waste Control (Washington, D.C., 1984), 190.
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The disposal of hazardous waste in deep geological formations through the use of underground injection
wells is controversial. Texas officials believe injection wells, when operated correctly, are safe; however, many environmental groups are concerned about the
heavy reliance on this technology, particularly by the commercial facilities that must manage a wide variety of hazardous wastes. Texas injects more liquid
hazardous wastes underground than any other state .*
In the 1930s, oil and gas exploration and production companies began injecting saltwater by-products back
into the oil-producing underground strata. The first manufacturing industry to use this same technique to inject industrial hazardous waste underground in Texas
was DuPont, which began a waste injection operation in 1953. Most underground injection wells in Texas inject the waste into oil-producing formations.*
The 1984 amendments to the RCRA prohibited land disposal, including underground injection, of certain
types of hazardous waste without pretreatment. However, if an operator of the injection well can prove the waste will not migrate from the injection zone for
10,000 years, the company can inject hazardous wastes into wells without first treating the waste.
Texas regulates the injection of hazardous waste through permits. About 200 permits to operate injection
wells disposing of hazardous or nonhazardous wastes have been granted in Texas since 1961. Currently, there are 102
Class I injection wells permitted and operating in Texas, with about half injecting only "non-hazardous waste" and the
other half authorized to inject both non-hazardous and hazardous industrial waste.* Most are located in the coastal
area and dispose of wastes associated with the petrochemical industry. In 1993 there were nine commercial facilities actively receiving hazardous waste. By 1997 there were just six commercial sites, and by 1999 only two facilities were actively taking hazardous waste for injection from other industrial facilities*. Finally, four facilities in Texas have recently been permitted to accept Class I nonhazardous waste on a commercial basis.*
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LEADING CHEMICALS INJECTED UNDERGROUND
IN TEXAS, 2001
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CHEMICAL
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POUNDS
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Ammonia
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15,014,390
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Nitrate Compounds
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9,811,282
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Methanol
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6,598,109
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Acetonitrile
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5,927,972
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Acrylamide
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5,033,641
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Acrylonitrile
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4,698,959
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Acrylic Acid
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3,775,900
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Nitric Acid
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3,323,857
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Cyanide Compounds
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2,318,332
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N-Methyl-2-Pyrrolidone
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1,985,101
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Cyclohexanol
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1,742,000
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Hydrogen Cyanide
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1,698,997
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Formic Acid
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1,556,020
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Phenol
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1,060,644
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Formaldehyde
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951,240
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Acetophenone
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751,810
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Propargyl Alcohol
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747,137
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SEC-Butyl Alcohol
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690,466
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Sulfuric Acid (Aerosols Only)
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679,045
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Ethylbenzene
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651,917
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Acetamide
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636,766
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Tert-Butyl Alcohol
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614,067
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Source: U.S. Environmental Protection Agency, 2001 Toxics Release
Inventory Database, 2003.
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In 1999, 14.1 million tons of Texas-generated hazardous
waste were injected at on-site facilities, while another 138,000 tons of Texas-generated waste and 57,000 tons of out-of-state waste were injected at two commercial facilities.* In 2001, industries in Texas reported injected over 77.6 million pounds of toxic chemicals and compounds underground*. Acidic chemicals such as
nitric acid, acrylic acid, formic acid, sulfuric and hydrochloric acid are commonly injected in Texas. Opponents of injection wells have argued that these
acidic chemicals have the potential to eat away formations and wells and migrate upward to contaminate groundwater.
Contamination resulting from the injection of salt water and other oil and gas production waste is also of
concern to Texans. These injection operators are regulated by the Railroad Commission of Texas, rather than the TCEQ or the EPA. The Railroad Commission of
Texas has jurisdiction over injection wells used to inject oil and gas wastes -- mainly saltwater -- injection wells to be used for secondary recovery and those used to
store hydrocarbons underground. As of December of 2002, the Railroad Commission reported that it had permitted 51,338 so-called Class II injection wells,
33,026 of which were active. The vast majority of these consisted of secondary-recovery wells (about 25,000), while there were about 8,000 saltwater disposal wells
and some 500 active hydrocarbon and gas storage wells.* Two confirmed cases of groundwater contamination resulting from injection wells have been
documented in the past few years, though both have since been cleaned up.*
Officials agree that waste disposal through properly constructed and operated injection wells is safer and
less likely to contaminate surface water or potable ground water than are landfills and other forms of land treatment.* For example, injection of hazardous wastes into
aquifers that serve or could serve as groundwater supplies for communities is not allowed. However, there are several
pathways by which wastes injected underground could contaminate water resources: *
- injection of waste above aquifers containing drinkable water;
- leakage of waste through inadequate confining beds;
- leakage of waste through confining beds due to hydraulic fracture or faults;
- displacement of saline water into a potable aquifer;
- upward migration of waste liquid from the injection zone along the outside of the well casing;
- escape into potable aquifers due to well-bore failures; and
- vertical migration and leakage to land and aquifers through abandoned oil, gas, and other wells.
Because the areas in which deep well injection of hazardous wastes is practiced in Texas are precisely those areas
with a long history of oil and gas production, there are many possible routes for vertical migration of hazardous waste
to the surface. State and federal regulations require those seeking to inject industrial and hazardous wastes to survey
existing wells within their injection area. They are also required to actively monitor their injection wells for possible
leakage of the casing. Still, the possibility exists that old oil and gas wells may not be located or were not adequately plugged, or that migration could occur outside of the injection zone.
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FYI
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Hazardous waste must be in liquid form before it can be injected underground. In
1983 the EPA estimated that only four percent of the 11.5 billion gallons of hazardous waste were toxic contaminants; the remainder was water.
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Source: U.S. General Accounting Office, Hazardous Waste: Controls
over Injection Well Disposal Operations [1987], 11.
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In Texas the only confirmed case where injected hazardous waste
contaminated underground drinking water occurred near Beaumont in 1975, before more stringent well-design standards were enacted.*
Soil contamination also resulted from an industrial injection operation when gas apparently formed within the well, causing the wastes to
"blow out," sending wastes into the air and over the land.* Spills at the surface during the handling of the wastes prior to injection can
also contaminate soils and groundwater prior to injection and have occurred in Texas. In fact, the most likely public health and
environmental impacts are from spills and transportation accidents of commercial facilities receiving wastes, not the injection process itself.
Citizens who lived near the American Ecology facility—formerly Gibraltar Chemical—in Kilgore, Smith County, filed numerous complaints with the then-TNRCC concerning spills, air
pollution, and health impacts.* In addition, the leading cost of reclamation of Class I injection wells is the cleanup of
any spills surrounding the well.* |
