{"data":{"id":"us/40-cfr-146.3","jurisdiction":"us","citation":"40 CFR 146.3","heading":"Definitions.","body":"The following definitions apply to the underground injection control program.\nAbandoned well means a well whose use has been permanently discontinued or which is in a state of disrepair such that it cannot be used for its intended purpose or for observation purposes.\nAdministrator means the Administrator of the United States Environmental Protection Agency, or an authorized representative.\nApplication means the EPA standard national forms for applying for a permit, including any additions, revisions or modifications to the forms; or forms approved by EPA for use in approved States, including any approved modifications or revisions. For RCRA, application also includes the information required by the Director under § 122.25 (contents of Part B of the RCRA application).\nAquifer means a geological formation, group of formations, or part of a formation that is capable of yielding a significant amount of water to a well or spring.\nArea of review means the area surrounding an injection well described according to the criteria set forth in § 146.06 or in the case of an area permit, the project area plus a circumscribing area the width of which is either 1/4 of a mile or a number calculated according to the criteria set forth in § 146.06.\nCasing means a pipe or tubing of appropriate material, of varying diameter and weight, lowered into a borehole during or after drilling in order to support the sides of the hole and thus prevent the walls from caving, to prevent loss of drilling mud into porous ground, or to prevent water, gas, or other fluid from entering or leaving the hole.\nCatastrophic collapse means the sudden and utter failure of overlying “strata” caused by removal of underlying materials.\nCementing means the operation whereby a cement slurry is pumped into a drilled hole and/or forced behind the casing.\nCesspool means a “drywell” that receives untreated sanitary waste containing human excreta, and which sometimes has an open bottom and/or perforated sides.\nConfining bed means a body of impermeable or distinctly less permeable material stratigraphically adjacent to one or more aquifers.\nConfining zone means a geological formation, group of formations, or part of a formation that is capable of limiting fluid movement above an injection zone.\nContaminant means any physical, chemical, biological, or radiological substance or matter in water.\nConventional mine means an open pit or underground excavation for the production of minerals.\nDirector means the Regional Administrator, the State director or the Tribal director as the context requires, or an authorized representative. When there is no approved State or Tribal program, and there is an EPA administered program, “Director” means the Regional Administrator. When there is an approved State or Tribal program, “Director” normally means the State or Tribal director. In some circumstances, however, EPA retains the authority to take certain actions even when there is an approved State or Tribal program. (For example, when EPA has issued an NPDES permit prior to the approval of a State program, EPA may retain jurisdiction over that permit after program approval; see § 123.69). In such cases, the term Director means the Regional Administrator and not the State or Tribal director.\nDisposal well means a well used for the disposal of waste into a subsurface stratum.\nDrywell means a well, other than an improved sinkhole or subsurface fluid distribution system, completed above the water table so that its bottom and sides are typically dry except when receiving fluids.\nEffective date of a UIC program means the date that a State UIC program is approved or established by the Administrator.\nEnvironmental Protection Agency (“EPA”) means the United States Environmental Protection Agency.\nEPA means the United States “Environmental Protection Agency.”\nExempted aquifer means an aquifer or its portion that meets the criteria in the definition of “underground source of drinking water” but which has been exempted according to the procedures of § 144.8(b).\nExisting injection well means an “injection well” other than a “new injection well.”\nExperimental technology means a technology which has not been proven feasible under the conditions in which it is being tested.\nFacility or activity means any “HWM facility,” UIC “injection well,” NPDES “point source,” or State 404 dredge and fill activity, or any other facility or activity (including land or appurtenances thereto) that is subject to regulation under the RCRA, UIC, NPDES, or 404 programs.\nFault means a surface or zone of rock fracture along which there has been displacement.\nFlow rate means the volume per time unit given to the flow of gases or other fluid substance which emerges from an orifice, pump, turbine or passes along a conduit or channel.\nFluid means material or substance which flows or moves whether in a semisolid, liquid, sludge, gas, or any other form or state.\nFormation means a body of rock characterized by a degree of lithologic homogeneity which is prevailingly, but not necessarily, tabular and is mappable on the earth's surface or traceable in the subsurface.\nFormation fluid means “fluid” present in a “formation” under natural conditions as opposed to introduced fluids, such as drilling mud.\nGenerator means any person, by site location, whose act or process produces hazardous waste identified or listed in 40 CFR part 261.\nGround water means water below the land surface in a zone of saturation.\nHazardous waste means a hazardous waste as defined in 40 CFR 261.3.\nHazardous Waste Management facility (“HWM facility”) means all contiguous land, and structures, other appurtenances, and improvements on the land used for treating, storing, or disposing of hazardous waste. A facility may consist of several treatment, storage, or disposal operational units (for example, one or more landfills, surface impoundments, or combination of them).\nHWM facility means “Hazardous Waste Management facility.”\nImproved sinkhole means a naturally occurring karst depression or other natural crevice found in volcanic terrain and other geologic settings which have been modified by man for the purpose of directing and emplacing fluids into the subsurface.\nIndian Tribe means any Indian Tribe having a Federally recognized governing body carrying out substantial governmental duties and powers over a defined area.\nInjection well means a “well” into which “fluids” are being injected.\nInjection zone means a geological “formation”, group of formations, or part of a formation receiving fluids through a well.\nLithology means the description of rocks on the basis of their physical and chemical characteristics.\nOwner or operator means the owner or operator of any facility or activity subject to regulation under the RCRA, UIC, NPDES, or 404 programs.\nPacker means a device lowered into a well to produce a fluid-tight seal.\nPermit means an authorization, license, or equivalent control document issued by EPA or an “approved State” to implement the requirements of this part and parts 124, 144, and 145. Permit does not include RCRA interim status (§ 122.23), UIC authorization by rule (§§ 144.21 to 144.26 and 144.15), or any permit which has not yet been the subject of final agency action, such as a “draft permit” or a “proposed permit.”\nPlugging means the act or process of stopping the flow of water, oil or gas into or out of a formation through a borehole or well penetrating that formation.\nPlugging record means a systematic listing of permanent or temporary abandonment of water, oil, gas, test, exploration and waste injection wells, and may contain a well log, description of amounts and types of plugging material used, the method employed for plugging, a description of formations which are sealed and a graphic log of the well showing formation location, formation thickness, and location of plugging structures.\nPoint of injection for Class V wells means the last accessible sampling point prior to waste fluids being released into the subsurface environment through a Class V injection well. For example, the point of injection of a Class V septic system might be the distribution box—the last accessible sampling point before the waste fluids drain into the underlying soils. For a dry well, it is likely to be the well bore itself.\nPressure means the total load or force per unit area acting on a surface.\nProject means a group of wells in a single operation.\nRadioactive waste means any waste which contains radioactive material in concentrations which exceed those listed in 10 CFR part 20, appendix B, table II column 2.\nRCRA means the Solid Waste Disposal Act as amended by the Resource Conservation and Recovery Act of 1976 (Pub. L. 94-580, as amended by Pub. L. 95-609, 42 U.S.C. 6901 et seq.).\nSanitary waste means liquid or solid wastes originating solely from humans and human activities, such as wastes collected from toilets, showers, wash basins, sinks used for cleaning domestic areas, sinks used for food preparation, clothes washing operations, and sinks or washing machines where food and beverage serving dishes, glasses, and utensils are cleaned. Sources of these wastes may include single or multiple residences, hotels and motels, restaurants, bunkhouses, schools, ranger stations, crew quarters, guard stations, campgrounds, picnic grounds, day-use recreation areas, other commercial facilities, and industrial facilities provided the waste is not mixed with industrial waste.\nSDWA means the Safe Drinking Water Act (Pub. L. 95-523, as amended by Pub. L. 95-190, 42 U.S.C. 300(f) et seq.).\nSeptic system means a “well” that is used to emplace sanitary waste below the surface and is typically comprised of a septic tank and subsurface fluid distribution system or disposal system.\nSite means the land or water area where any facility or activity is physically located or conducted, including adjacent land used in connection with the facility or activity.\nSole or principal source aquifer means an aquifer which has been designated by the Administrator pursuant to section 1424 (a) or (e) of the SDWA.\nState Director means the chief administrative officer of any State, interstate, or Tribal agency operating an “approved program,” or the delegated representative of the State Director. If the responsibility is divided among two or more State, interstate, or Tribal agencies, “State Director” means the chief administrative officer of the State, interstate, or Tribal agency authorized to perform the particular procedure or function to which reference is made.\nStratum (plural strata) means a single sedimentary bed or layer, regardless of thickness, that consists of generally the same kind of rock material.\nSubsidence means the lowering of the natural land surface in response to: Earth movements; lowering of fluid pressure; removal of underlying supporting material by mining or solution of solids, either artificially or from natural causes; compaction due to wetting (Hydrocompaction); oxidation of organic matter in soils; or added load on the land surface.\nSubsurface fluid distribution system means an assemblage of perforated pipes, drain tiles, or other similar mechanisms intended to distribute fluids below the surface of the ground.\nSurface casing means the first string of well casing to be installed in the well.\nTotal dissolved solids (“TDS”) means the total dissolved (filterable) solids as determined by use of the method specified in 40 CFR part 136.\nUIC means the Underground Injection Control program under Part C of the Safe Drinking Water Act, including an “approved program.”\nUnderground injection means a “well injection.”\nUnderground source of drinking water (USDW) means an aquifer or its portion:\n(1)(i) Which supplies any public water system; or\n(ii) Which contains a sufficient quantity of ground water to supply a public water system; and\n(A) Currently supplies drinking water for human consumption; or\n(B) Contains fewer than 10,000 mg/l total dissolved solids; and\n(2) Which is not an exempted aquifer.\nUSDW means “underground source of drinking water.”\nWell means: A bored, drilled, or driven shaft whose depth is greater than the largest surface dimension; or, a dug hole whose depth is greater than the largest surface dimension; or, an improved sinkhole; or, a subsurface fluid distribution system.\nWell injection means the subsurface emplacement of fluids through a well.\nWell plug means a watertight and gastight seal installed in a borehole or well to prevent movement of fluids.\nWell stimulation means several processes used to clean the well bore, enlarge channels, and increase pore space in the interval to be injected thus making it possible for wastewater to move more readily into the formation, and includes (1) surging, (2) jetting, (3) blasting, (4) acidizing, (5) hydraulic fracturing.\nWell monitoring means the measurement, by on-site instruments or laboratory methods, of the quality of water in a well.","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER D—WATER PROGRAMS","PART 146—UNDERGROUND INJECTION CONTROL PROGRAM: CRITERIA AND STANDARDS","Subpart A—General Provisions"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"73c425312d6d8536e7246b574e6ed5ca2ab4beb2f2a190309be5c567741945fd","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-146.2","next":"us/40-cfr-146.4"},"notice":"GroundRules: Original legal text. Not legal advice."}