Deep Well Injection of Hazardous Wastes

Quartz is present throughout, and is relatively unaffected. In the presence of quartz, kaolinite is the expected aluminosilicate phase. However, as mentioned above, gibbsite (Al(OH)3) or a gibbsite-like phase (such as one of its polymorphs, or an amorphous phase) is often found apparently to be controlling the dissolved A1 concentration. Very similar buffering stages would be observed in this case. 

Class I Injection of municipal or industrial waste below the deepest USDW. 

Class IV Injection of hazardous or radioactive waste into or above USDW. 

Class V All other wells used for injection of fluids. 

The enactment of the Resource Conservation and Recovery Act (RCRA) in 1984 resulted in EPA amendments to regulations in 1988, which prohibit underground injection of hazardous wastes, unless such injection is granted with an exemption from EPA (40 CFR 124,144,146, and 148). An exemption can only be granted by going through a process commonly known as no-migration demonstration or petition. The owners and 

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U.S. EPA regulations (53 Federal Register 28118-28157, July 26,1988) stipulate that deep-well injection of hazardous wastes is allowed only if either of the following two no-migration standards is met3 ... 

Water with a salinity of less than 10,000 mg/L is considered to be a potential underground source of drinking water. By regulatory definition, deep-well injection of hazardous waste can occur only in very saline waters or brines. Actual salinities of waters in currently used deep-well injection zones vary greatly.70 Normally, the term brine is used to refer to the natural waters in deep-well injection zones. As noted above, however, this term is not technically correct if TDS levels are less than 35,000 mg/L. 

Reeder, L.R., Review and Assessment of Deep-Well Injection of Hazardous Wastes, EPA 600/2-77-029a-d, NTIS PB 269 001-004, U.S. EPA, Washington, 1977. 

Chemicals may enter groundwater as landfill leachates or from deep-well injection of hazardous wastes, leaching from soil and water, or septic tanks. Diffusion and advection are the typical mechanisms of chemical transport in groundwater. Groundwater may be taken up via human use or empty onto the surface waters via a natural spring. 

Strycker, A. and Collins, A.G., State-of-the-Art Report Injection of Hazardous Wastes into Deep Wells, EPAI600/8-87/01 3, NTIS PB87-1 70551, U.S. EPA, Washington, 1987. 

Applications Deep-well injection has been used principally for liquid wastes that are difficult to treat and dispose of by more conventional methods and for hazardous wastes. Chemical, petrochemical, and pharmaceutical wastes are those most commonly disposed of with this method. The waste may be liquid, gases, or solids. The gases and solids are either dissolved in the liquid or are carried along with the liquid. 

Disposal involves the use of postprocess activities that can handle waste, such as deep-well injection and off-site shipment of hazardous materials to waste-management facilities. 

The technology of deep-well injection has been around for more than 70 years. Most Americans would be surprised to know that there is a waste management system already in operation in the U.S. that has no emissions into the air, no discharges to surface water, and no off-site transfers, and exposes people and the environment to virtually no hazards. 1 The U.S. Environmental Protection Agency (U.S. EPA) has stated that Class 1 wells are safer than virtually all other waste disposal practices for many chemical industry wastes. 

The sources, amounts, and composition of existing deep-well-injected hazardous wastes... 

Source U.S. EPA, Assessing the Geochemical Fate of Deep-Well-Injected Hazardous Waste A Reference Guide, EPA/625/ 6-89/025a, U.S. EPA, Cincinnati, OH, June 1990. 

A waste is toxic under 40 CFR Part 261 if the extract from a sample of the waste exceeds specified limits for any one of eight elements and five pesticides (arsenic, barium, cadmium, chromium, lead, mercury, selenium, silver, endrin, methoxychlor, toxaphene, 2,4-D and 2,4,5-TP Silvex using extraction procedure (EP) toxicity test methods. Note that this narrow definition of toxicity relates to whether a waste is defined as hazardous for regulatory purposes in the context of this chapter, toxicity has a broader meaning because most deep-well-injected wastes have properties that can be toxic to living organisms. 

The sources, amounts, and composition of injected hazardous wastes are a matter of record, because the Resource Conservation and Recovery Act (RCRA)5,14 requires hazardous waste to be manifested (i.e., a record noting the generator of the waste, its composition or characteristics, and its volume must follow the waste load from its source to its ultimate disposal site). The sources and amounts of injected hazardous waste can be determined, therefore, based on these records. Table 20.2 shows the estimated volume of deep-well-injected wastes by industrial category.3 More than 11 billion gallons of hazardous waste were injected in 1983. Organic chemicals (51%) and petroleum-refining and petrochemical products (25%) accounted for three-quarters of the volume of injected wastes that... 

This section examines the major processes that affect the fate of deep-well-injected hazardous wastes. The focus is on processes that (1) are known to occur in the deep-well environment or (2) have not been directly observed but are theoretically possible. 

Transformation processes change the chemical structure of a compound. Because not all transformation processes convert hazardous wastes to nonhazardous compounds, geochemical fate assessment must consider both the full range of transformation processes that may occur and the toxicity and mobility of the resulting products. For deep-well-injected wastes, transformation processes and subsequent reactions may lead to one or more of the following ... 

The actual movement of a specific deep-well-injected hazardous substance depends on the types of processes that act on the waste and on the ways in which different processes interact. Figure 20.3 shows the expected change in concentration over time of a deep-well-injected organic compound in an observation well at an unspecified distance from the original point of injection. 

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