The Safe Drinking Water Act (SDWA) was enacted in 1974 due to concerns with the public's potable water system. The act created two major initiatives. The first allowed the United States Environmental Protection Agency (USEPA) to set enforceable standards for health-related drinking water contaminants for all public water supplies. The second gave the USEPA responsibility for developing a broad ground water protection program known as the Underground Injection Control (UIC) program (Bedient et. al., 1994).
The SDWA requires the USEPA to create national primary drinking water regulations (NPDWR) that:
A public water system is a system that provides piped water to the public for human consumption. It is defined specifically as a water supply with at least 15 service connections or that regularly serves at least 25 individuals. An MCL is the maximum allowable concentration of a contaminant in water that is delivered to any user of a public water system. In addition, the SDWA provides for the creation of secondary MCLs, which are nonenforceable limits recommended for the aesthetics of drinking water. Treatment techniques are required only if it is economically or technically unfeasible to measure the concentration of a specific contaminant in potable water (Pontius, 1990).
A technician at the Blacksburg/ Christiansburg /VPI Water Authority in Virginia collects a sample of tap water for testing. Photo by V. Burris.
The NPDWR also require the USEPA to establish maximum contaminant level goals (MCLGs). MCLGs are nonenforceable health goals for public water supplies. They are set at levels which "no known or anticipated adverse effects on the health of persons occur and allow an adequate margin of safety." MCLs are to be set as close to the MCLGs as feasible. Feasibility is based particularly on the available treatment technology, taking cost into consideration (Pontius, 1990).
A major set of amendments was added to the SDWA in 1986 due to congressional concerns that the USEPA was not developing MCLs at an acceptable rate. One of the most important requirements of the amendments is that USEPA must develop 25 new MCLs every three years. The amendments also required the USEPA to specify criteria under which filtration would be mandatory for water supplies with surface water sources. They also specify that all public water systems are required to practice disinfection. Public water suppliers are also required to keep records, make reports, conduct monitoring, and provide other such information as needed to determine if they are in compliance (Pontius, 1990).
Daily logs maintained by the Blacksburg/ Christiansburg /VPI Water Authority in Virginia. Photo by V. Burris.
Public participation is also addressed in the SDWA. The public has at least two opportunities in the approval process to comment on proposed MCLs and MCLGs. In addition, any violation of an MCL, failure to comply with an applicable testing provision, or failure to comply with any monitoring must be reported to the people served by the water system.
A technician at the Blacksburg /Christiansburg /VPI Water Authority in Virginia conducts a jar test to determine the appropriate chemical dosage for water treatment. Photo by V. Burris.
A technician at the Blacksburg /Christiansburg /VPI Water Authority in Virginia performs an alkalinity titration. Photo by V. Burris.
The (UIC) program was designed to protect ground water from contamination by the subsurface injection of liquid wastes into wells. The practice of underground waste disposal has long been performed, with the contamination of underground sources of drinking water (USDWs) resulting from improper well design and waste handling. Since nearly half of the United States population uses ground water as its primary source of drinking water, growing concern has developed over its contamination (Bedient et. al., 1994).
Under federal regulations, a well is broadly defined as any constructed hole having a depth that is greater than its width. Through underground injection, liquid wastes are deposited into wells at high pressures. To protect against the contamination of nearby ground water sources, injection wells must be cased and cemented into the surrounding foundation (Bedient et. al., 1994).
A typical underground injection well (Bedient et. al, 1994 and Lesage, 1991). Illustration by J. Phillips.
The UIC program identifies five specific classes of underground injection wells subject to regulation:
The USEPA developed general regulations governing underground injection, but the authority to implement this program was delegated to the states. Each state may choose to allow or prohibit the underground injection of wastes. However, if such disposal is permitted, the state is required to develop a control program incorporating federal rules that ensure underground injection does not jeopardize drinking water sources. Such endangerment is defined as the introduction of a pollutant into an underground water source, thereby causing a violation of the primary drinking water standards (Bedient et. al., 1994).
In order to obtain a permit authorizing liquid waste injection, site review and construction design are required for the permit review process. Such review must ensure that wastes will be injected beneath the lowest drinking water source into a structurally sound well that demonstrates a resistance to leakage. In addition, wastes must be deposited into an appropriately permeable geologic formation encompassed by impermeable subsurface layers that are free of faults and fractures. In order to ensure proper operation of injection wells after installation, the UIC program requires remote sensing and evaluations of functioning wells to ensure that the waste is being deposited into the injection zone (Bedient et. al., 1994).
Since underground injection does not involve pretreatment of the liquid wastes, it is classified as a land disposal and storage method. The Hazardous and Solid Waste Amendments of 1984 prohibited land deposition of hazardous waste, including injection into wells. However, USEPA's examination of injection wells revealed that no transport of wastes would occur for thousands of years, and therefore exempted underground injection wells from the ban (Bedient et. al., 1994).
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Faculty Advisor: Daniel Gallagher, dang@vt.edu
Copyright © 1998 Daniel Gallagher
Last Modified: June 7, 1998
