A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z
User Advisory Committee.
Urban Airshed Model.
Utility Acid Precipitation Study Program.
Uniform Air Quality Index.
Utility Air Regulatory Group.
ubiquitous background levels
concentrations of chemicals that are present in the environment due to anthropogenic sources (e.g., industry, automobiles).
Ultra Clean Coal.
Unsymmetrical Dimethyl Hydrazine.
See Upper Explosive Limit, Upper Flammable Limit.
See Upper Explosive Limit, Upper Flammable Limit.
Upper Flammability Limit.
ultra clean coal (UCC)
coal that has been washed, ground into fine particles, then chemically treated to remove sulfur, ash, silicone, and other substances; usually briquette and coated with a sealant made from coal.
radiation from the sun that can be useful or potentially harmful. UV rays from one part of the spectrum enhance plant life and are useful in some medical and dental procedures; UV rays from other parts of the spectrum to which humans are exposed (e.g., while getting a sun tan) can cause skin cancer or other tissue damage. The ozone layer in the atmosphere provides a protective shield that limits the amount of ultraviolet rays that reach the Earth's surface.
Uranium Mill Tailings Radiation Control Act.
Users' Network for Applied Modeling of Air Pollution.
see Support Media.
means an underground room, such as a basement, cellar, shaft or vault, providing enough space for physical inspection of the exterior of the tank situated on or above the surface of the floor.
means any belowground release.
underground storage tank (or "UST")
means any one or combination of tanks (including underground pipes connected thereto) that is used to contain an accumulation of regulated substances, and the volume of which (including the volume of underground pipes connected thereto) is 10 percent or more beneath the surface of the ground. This term does not include any: (a) Farm or residential tank of 1,100 gallons or less capacity used for storing motor fuel for noncommercial purposes; (b) Tank used for storing heating oil for consumptive use on the premises where stored; (c) Septic tank; (d) Pipeline facility (including gathering lines) regulated under:(1) The Natural Gas Pipeline Safety Act of 1968 (49 U.S.C. App. 1671, et seq.), or(2) The Hazardous Liquid Pipeline Safety Act of 1979 (49 U.S.C. App. 2001, et seq.), or(3) Which is an intrastate pipeline facility regulated under state laws comparable to the provisions of the law referred to in paragraph (d)(1) or (d)(2) of this definition; (e) Surface impoundment, pit, pond, or lagoon; (f) Storm-water or wastewater collection system; (g) Flow-through process tank; (h) Liquid trap or associated gathering lines directly related to oil or gas production and gathering operations; or (i) Storage tank situated in an underground area (such as a basement, cellar, mineworking, drift, shaft, or tunnel) if the storage tank is situated upon or above the surface of the floor. term "underground storage tank (or "UST") does not include any pipes connected to any tank which is described in paragraphs (a) through (i) of this definition.
underground sources of drinking water
as defined in the UIC program, this term refers to aquifers that are currently being used as a source of drinking water, and those that are capable of supplying a public water system. They have a total dissolved solids content of 10,000 milligrams per liter or less, and are not "exempted aquifers". (See: exempted aquifer).
a single, discrete process as part of an overall sequence, e.g., precipitation, settling or filtration.
See DOT Identification Numbers; PIN.
when used in relation to section 311(a)(5) of the CWA, means the states, the District of Columbia, the Commonwealth of Puerto Rico, the Northern Mariana Islands, Guam, American Samoa, the United States Virgin Islands, and the Pacific Island Governments. United States, when used in relation to section 101(27) of CERCLA, includes the several states of the United States, the District of Columbia, the Commonwealth of Puerto Rico, Guam, American Samoa, the United States Virgin Islands, the Commonwealth of the Northern Marianas, and any other territory or possession over which the United States has jurisdiction.
the area above the water table where the soil pores are not fully saturated, although some water may be present.
tending toward decomposition or other unwanted chemical change during normal handling or storage. An unstable chemical in its pure state, or as commonly produced or transported, polymerizes vigorously, decomposes, condenses, or becomes self-reactive under conditions of shock, pressure, or temperature. See Stability. See Stability, Reactive.
means the addition or retrofit of some systems such as cathodic protection, lining, or spill and overfill controls to improve the ability of an underground storage tank system to prevent the release of product.
Upper Explosive Limit, Upper Flammable Limit
UEL, UFL. The highest concentration of a material in air that produces an explosion in fire or ignites when it contacts an ignition source (high heat, electric arc, spark, or flame). A higher concentration of the material in a smaller percentage of concentration of air may be too rich to be ignited. See Flammable Limits.
a radioactive heavy metal element used in nuclear reactors and the production of nuclear weapons. Term refers usually to U 238, the most abundant radium isotope, although a small percentage of naturally occurring uranium is U 235.
storm water from city streets, usually carrying litter and organic wastes.
nettle rash; hives; elevated, itching, white patches.
United States Army.
United States Air Force.
United States Attorney's Office.
United States Army Toxic and Hazardous Materials Agency.
United States Bureau of Mines.
United States Bureau of Standards.
United States Code.
United States Code Annotated.
United States Coast Guard.
United Soil Classification System.
United States Department of Agriculture.
United States Department of the Interior.
Underground Sources of Drinking Water.
United States Environmental Protection Agency.
United States Forest Service.
United States Geological Survey, Department of the Interior.
United States Marine Corps.
United States Navy.
United States Nuclear Regulatory Commission.
United States Public Health Service.
United States Postal Service.
underground storage tank; regulated by RCRA; tank with 10 or more percent of its volume underground with connected piping; used to store petroleum products or CERCLA regulated hazardous chemicals.
UST system or "Tank system"
means an underground storage tank, connected underground piping, underground ancillary equipment, and containment system, if any.
Utility Solid Waste Activities Group.
Universal Transverse Mercator.
Unsaturated Zone Monitoring.