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Glossary of Terms GLOSSARY OF TERMS For the purpose of this Handbook, the following definitions and abbreviations shall apply. Although all of the definitions and abbreviations listed below may have not been used in this Handbook, the additional terminology is provided to assist the user of Handbook in understanding technical terminology associated with Drainage Improvement Projects and the associated regulations. Program-specific terms have been defined separately for each program and are contained in pertinent sub-sections of Section 2 of this handbook. ACRONYMS ASTM American Society for Testing Materials CBBEL Christopher B. Burke Engineering, Ltd. COE United States Army Corps of Engineers EPA Environmental Protection Agency IDEM Indiana Department of Environmental Management IDNR Indiana Department of Natural Resources NRCS USDA-Natural Resources Conservation Service SWCD Soil and Water Conservation District USDA United States Department of Agriculture USFWS United States Fish and Wildlife Service DEFINITIONS AASHTO Classification. The official classification of soil materials and soil aggregate mixtures for highway construction used by the American Association of State Highway and Transportation Officials. Abutment. The sloping sides of a valley that supports the ends of a dam. Acre-Foot. The volume of water that will cover 1 acre to a depth of 1 ft. Aggregate. (1) The sand and gravel portion of concrete (65 to 75% by volume), the rest being cement and water. Fine aggregate contains particles ranging from 1/4 in. down to that retained on a 200-mesh screen. Coarse aggregate ranges from 1/4 in. up to l½ in. (2) That which is installed for the purpose of changing drainage characteristics. Alluvial Soils. Soils developed from transported and relatively recently deposited material (alluvium) characterized by a weak modification (or none) of the original material by soil-forming A-1 processes. Alluvium. A general term for all detrital material deposited or in transit by streams, including gravel, sand, silt, clay, and all variations and mixtures of these. Unless otherwise noted, alluvium is unconsolidated. Anti-Seep Collar. A device constructed around a pipe or other conduit placed through a dam, levee, or dike for the purpose of preventing soil movement and piping failures. Anti-Vortex Device. A facility placed at the entrance to a pipe conduit structure, such as a drop inlet spillway or hood inlet spillway, to prevent air from entering the structure when the pipe is flowing full. Apron. A pad of non-erosive material designed to prevent scour holes developing at the outlet ends of culverts, outlet pipes, grade stabilization structures, and other water control devices. Aquifer. An underground porous, water-bearing geological formation. The term is generally restricted to materials capable of yielding an appreciable supply of water. ASTM. American Society for Testing Materials, an association that publishes standards and requirements for materials used in the construction industry. Backwater. The rise in water surface elevation caused by some obstruction such as a narrow bridge opening, buildings or fill material that limits the area through which the water shall flow. Barrel. A conduit placed through a dam, levee, or dike to control the release of water. Base Flood. See "Regulatory Flood". Base Flood Elevation (BFE). The water surface elevation corresponding to a flood having a one percent probability of being equalled or exceeded in a given year. Base Flow. Stream discharge derived from groundwater sources as differentiated from surface runoff. Sometimes considered to include flows from regulated lakes or reservoirs. Bearing Capacity. The maximum load that a material can support before failing. Bedrock The more or less solid rock in place either on or beneath the surface of the earth. It may be soft, medium, or hard and have' a smooth or irregular surface. Benchmark. A marked point of known elevation from which other elevations may be established. Bentonite. A highly plastic clay consisting of the minerals, montmorillonite, and beidellite that swell extensively wet. Often used to seal soil to reduce seepage losses. Berm. A narrow shelf or flat area that breaks the contiguity of a slope. Best Management Practices. Design, construction, and maintenance practices and criteria for A-2 stormwater facilities that minimize the impact of stormwater runoff rates and volumes, prevent erosion, and capture pollutants. Borrow Area. A source of earth fill material used in the construction of embankments or other earth fill structures. Capacity of a Storm Drainage Facility. The maximum flow that can be conveyed or stored by a storm drainage facility without causing damage to public or private property. Capillary Action. The tendency of drier soil particles to attract moisture from wetter portions of soil. Catch Basin. A chamber usually built at the curb line of a street for the admission of surface water to a storm sewer or subdrain, having at its base a sediment sump designed to retain grit and detritus below the point of overflow. Centerline of Channel. The middle point or baseline of a channel. Channel. A portion of a natural or artificial watercourse which periodically or continuously contains moving water, or which forms a connecting link between two bodies of water. It has a defined bed and banks which serve to confine the water. Channel Improvement. Alteration, maintenance, or reconstruction of the channel area for the purpose of improving the channel capacity or overall drainage efficiency. The noted "improvement" does not necessarily imply water quality or habitat improvement within the channel or its adjacent area. Channel Stabilization. Protecting the sides and bed of a channel from erosion by controlling flow velocities and flow directions using jetties, drops, or other structures and/or by fining the channel with vegetation, riprap, concrete, or other suitable lining material. Channelization. Alteration of a stream channel by widening, deepening, straightening, or paving certain areas to improve flow characteristics. Chicken Wire. A woven wire fabric with an opening size of about 1½ in. Chute. A high-velocity, open channel (usually paved) for conveying water down a steep slope without erosion. Classified Filter Strip. A parcel of land that has been or will be classified as filter strip for the purpose of property assessment and taxation. The details of the associated procedures and criteria are contained in IC 6-1.1-6.7 . See also Filter Strip. Clay. (1) Soil fraction consisting of particles less than 0.002 mm in diameter. (2) A soil texture class that is dominated by clay or at least has a larger proportion of clay than either silt or sand. Cohesion. The capacity of a soil to resist shearing stress, exclusive of functional resistance. Cohesive Soil. A soil that, when unconfined, has considerable strength when air-dried and A-3 significant strength when saturated. Companion (nurse) Crop. A crop sown with another crop that will germinate quickly and provide a protective vegetative cover until the preferred species can become established. The crop, usually small grain, is sown with a legume or perennial grass species. Compost. Organic residue (or a mixture of organic residue and soil) that has undergone biological decomposition until it has become relatively stable humus. Contour. An imaginary line on the surface of the earth connecting points of the same elevation. Contour Line. Line on a map which represents a contour or points of equal elevation. Control Structure. A structure designed to control the rate of flow that passes through the structure, given a specific upstream and downstream water surface elevation. County Surveyor. A constitutional officer of the county, elected to a 4-year term from the county at large. Primary duties of the surveyor includes maintaining annexation descriptions, legal survey book, and section corner record book. Surveyor is also an ex-officio member of the County Drainage Board and the technical authority on the construction, reconstruction, and maintenance of all regulated drains or proposed regulated drains in the county. Other major responsibilities of the surveyor includes administering filter strip programs, membership in the County Plan Commission, and certification to the Indiana Alcoholic Beverage Commission. Crown of Pipe. The elevation of the top of pipe. Cross-Section. A graph or plot of ground elevation across a stream valley or a portion of it, usually along a line perpendicular to the stream or direction of flow. Cultipacker Seeder. A seeder equipped with an attachment that will firm the seedbed to increase seed-to-soil contact. Culvert. A closed conduit used for the conveyance of surface drainage water under a roadway, railroad, canal or other impediment. Cut. (1) A portion of land surface or area from which earth has been removed or will be removed by excavating. (2) The depth below the original ground surface to the excavated surface. Cutoff Trench. A long, narrow excavation (keyway) constructed along the center line of a dam, dike, levee, or embankment and filled with relatively impervious material intended to reduce seepage of water through porous strata. Cutting. A detached leaf stem or piece of root that is encouraged to form roots. A greenwood cutting is made during the period of active growth. A hardwood cutting is made during the dormant season. Cut-and-Fill. The process of earth grading by excavating part of a higher area and using the excavated material for fill to raise the surface of an adjacent lower area. A-4 Dam. A barrier to confine or impound water for storage or diversion, to prevent gully erosion, or to retain soil, sediment, or other debris. Datum. Any level surface to which elevations are referred, usually using Mean Sea Level. Design Life. The period of time for which a facility is expected to perform its intended function. Design Storm. A selected storm event, described in terms of the probability of occurring once within a given number of years, for which drainage or flood control improvements are designed and built.
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