Science Terms Definitions - W

Waste Isolation Pilot Plant (WIPP) - The WIPP, which is under development by the Department of Energy, is a potential geologic disposal facility for transuranic (TRU) radioactive waste generated as by-products from DOE's nuclear weapons production. The WIPP is located underground in excavated, natural salt formations, near Carlsbad, New Mexico. Before DOE can dispose of waste at the WIPP, it must demonstrate that the WIPP complies with EPA's radioactive waste disposal standards. DOE must submit a "compliance application" to EPA showing how the WIPP facility will meet the standards. The WIPP facility is scheduled to begin operation in the Spring of 1998, subject to EPA approval of DOE's compliance application. Also, DOE plans to submit a petition to EPA, to demonstrate that Mixed TRU (MTRU) disposal at the WIPP will not migrate beyond the WIPP unit boundary, and therefore the waste would not need to be treated to meet RCRA Land Disposal Restrictions (LDR). At present, DOE is required to treat all MTRU to meet the appropriate LDR's.

Water Pollution - The addition of sewage, industrial wastes, or other harmful or objectionable material to water in concentrations or in sufficient quantities to result in measurable degradation of water quality.

Water Quality-Based Limitations - Effluent limitations applied to dischargers when mere technology-based limitations would cause violations of water quality standards. Usually applied to discharges into small streams.

Water Quality-Based Permit - A permit with an effluent limit more stringent than one based on technology performance. Such limits may be necessary to protect the designated use of receiving waters (i.e., recreation, irrigation, industry or water supply).

Water Quality Criteria - Levels of water quality expected to render a body of water suitable for its designated use. Criteria are based on specific levels of pollutants that would make the water harmful if used for drinking, swimming, farming, fish production, or industrial processes.

Water Quality Standards - State-adopted and EPA-approved ambient standards for water bodies. The standards prescribe the use of the water body and establish the water quality criteria that must be met to protect designated uses.

Water Table - Top of an unconfined aquifer, below which the pore spaces are saturated with water.

Watershed - The land area that drains into a stream; the watershed for a major river may encompass a number of smaller watersheds that ultimately combine at a common delivery point.

Well Injection - The subsurface emplacement of fluids into a well.

Well Monitoring - Measurement, by on-site instruments or laboratory methods, of the quality of water in a well.

Well Plug - A watertight and gastight seal installed in a bore hole or well to prevent movement of fluids.