An injection well is defined in the Texas Injection Well Act as an artificial excavation made for the purpose of injecting or disposing of industrial and municipal waste into subsurface strata. Industrial and municipal waste is defined as any liquid, gaseous, solid, or other waste substance which might be expected to cause pollution of fresh water.
Before any person may begin drilling an injection well or converting any existing well into an injection well for the purpose of disposing of industrial or municipal waste, a permit must be obtained from the Texas Water Quality Board, and a fee of $25 must accompany the application. A permit for drilling an injection well to be utilized for disposal of waste arising from the production of oil or gas must be obtained from the Railroad Commission of Texas.
An application to the Board for a permit or waste-control order must be accompanied by a letter from the Railroad Commission of Texas stating that the well will not en-danger any oil or gas resources- The Water Quality Board also is required to send copies of each application and subsequent waste-control order to the Texas Water Development Board, the Texas State Department of Health, and the Texas Water Well Drillers Board. The act does not require a public hearing on the application, but the Texas Water Quality Board, in adopting rules and regulations, deemed it to be in the public interest to hold a public hearing on all applications.
The technical staff of the Board reviews each application for completeness and assures that the proposed project is properly designed and that the reservoir is capable of receiving the waste without undue pressure increase. The staff makes recommendations to the Board for approval or denial of the waste-control order.
A waste-control order to drill an injection well may be granted by the Water Quality Board when it has been determined that this method of disposal has less effect on the environment than alternate methods of disposal, that the well will not impair any existing rights, and that both groundwater and surface waters can be protected from pollution. The waste-control order contains provisions and requirements deemed necessary to protect fresh waters.
The technical staff observes certain phases of the well completion, certifies the project upon completion, and conducts periodic inspections. The permittee must submit periodic reports on the wellhead injection pressure and on the volume and quality of the waste injected.
The most significant aspect of utilizing subsurface disposal is the availability of suitable reservoirs. Approximately 90 percent of Texas is underlain by strata favorable for subsurface disposal of waste. One hundred permits have been issued for the disposition of industrial and municipal waste into these subsurface reservoirs since adoption of the Injection Well Act.
The advantages of subsurface disposal of waste are that (1) the fate of the waste is, in general, known and understood; (2) the waste is contained and can be isolated from man's food, water, and activity; and (3) the waste can be recovered if desired, or if the need arises.
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This publication consists of papers based on oral presentations at a symposium of the same name co-sponsored by the United States Geological Survey and the American Association of Petroleum Geologists. A wide range of technical issues are covered, as well as regulatory and liability concerns. Documentation of two areas in Colorado where earthquakes had resulted from subsurface fluid injection set the stage for modern debates regarding possible similar results elsewhere. A wide range of fluid compositions are subject to subsurface waste disposal. The largest volumes are brines separated during the production of oil and gas wells, but acid-water and industrial wastes of all types can be disposed in significant quantities in local areas. Large hydraulic fracture treatments never recover all of the injected fluids, and the chemical additives in the fluid that remains underground can be a concern. The subsurface injection of radioactive waste is a topic for three of the papers. The possible need for sequestration of carbon dioxide was not a significant concern at the time and was not covered, but many of the papers provide insight into the issues related to modern proposals. When fluids are injected under pressure into subsurface aquifers, they interact in numerous ways. The fluids can potentially migrate for long distances and potentially interfere with other uses for the native aquifer fluids. If the aquifer cannot transport all of the fluids away, the buildup in pressure can cause fracturing of the rock. Differences in composition between the injected and native fluids can cause chemical reactions to occur; in some cases these can be desirable in that they can immobilize certain solutes in mineral form. The long-term environmental consequences are a common theme in many of the papers because of the recognition that the disposed fluids would become a permanent fixture in subsurface aquifers and could have long-term consequences for their future utilization.