NPDP Dam Dictionary

Browse by Letter:
All  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  


Term AKA Definition
Bedrock The solid rock at the surface or underlying other surface materials. Rock of relatively great thickness and extent in its native location. A general term for any solid rock, not exhibiting soil-like properties, that underlies soil or other unconsolidated surficial materials. As distinguished from boulders.
Bell An expanded end of a pipe section, into which the next pipe fits.
Bench A working level or step in a cut.
Bench mark BM A permanent or temporary monument of known elevation above sea level, used for vertical control at a construction site. A point of known or assumed elevation used as a reference in determining other elevations.
Berm A horizontal strip or shelf built into an embankment or cut to break the continuity of the slope, usually for the purpose of reducing erosion or to increase the thickness of the embankment at a point of change in slope or defined water surface elevation. A horizontal step in the sloping profile of an embankment dam. A shelf that breaks the continuity of a slope, or artificial ridge of earth. A ledge or shoulder, as along the edge of a road or canal. An artificial ridge of earth.
Bituminous Containing asphalt or tar.
Boring Rotary drilling.
Borrow Material excavated from one area to be used as fill material in another area.
Borrow areas Generally, surface areas, that contain borrow pits. The area from which material for an embankment is excavated.
Borrow pits Specific site(s) within a borrow area from which material is excavated for use.
Boulder A rock fragment, usually rounded by weathering or abrasion, with an average dimension of 12 inches or more: will not pass a 12-inch screen. A rock which is too heavy to be lifted readily by hand.
British thermal units BTU Quantity of heat required to raise the temperature of one avoirdupois pound of water 1øF at or near 39.2øF.
Bulkhead A one-piece fabricated steel unit which is lowered into guides and seals against a frame to close a water passage in a dam, conduit, spillway, etc. An object used to isolate a portion of a waterway for examination, maintenance, or repair. A wall or partition erected to resist ground or water pressure.
Bulking The increase in volume of a material due to manipulation. Rock bulks upon being excavated; damp sand bulks if loosely deposited, as by dumping, because the apparent cohesion" prevents movement of the soil particles to form a reduced volume."
Butt joint Open joint In pipe, flat ends that meet but do not overlap.
Butterfly valve A valve designed for quick closure that consists of a circular leaf, slightly convex in form, mounted on a transverse shaft carried by two bearings.
Buttress dam A dam consisting of a watertight upstream part supported at intervals on the downstream side by a series of buttresses (walls normal to the axis of the dam). Buttress dams can take many forms. See arch-buttress dam, flat slab or slab and buttress dam, massive head buttress dam, multiple arch dam, and solid head buttress dam.
By (Kilometers or Miles) Select the units (kilometers or miles) for the radial distance.
Cairn A pile of stones used as a marker.
Caisson A box or chamber used in construction work under water.
Camber The extra height added to the crest of embankment dams to ensure that the freeboard will not be diminished by foundation settlement or embankment consolidation. The amount of camber is different for each dam and is dependent on the amount of foundation settlement and embankment expected to occur.
Canal A channel, usually open, that conveys water by gravity to farms, municipalities, etc.
Canal headworks The beginning of a canal.
Canal prism The shape of the canal as seen in cross section.
Capacity The load for which a generator is rated. The maximum load that a machine, station, or system can carry under existing service conditions. Equivalent terms: peak capability, peak generation, firm peak load, carrying capability. In transmission, the maximum load a transmission line is capable of carrying. See excess capacity and peaking capacity.
Catchment basin Unit watershed; an area from which all the drainage water passes into one stream or other body of water.
Cavitation The formation of partial vacuums in fast-flowing water caused by subatmospheric pressures immediately downstream from an obstruction or offset. Usually accompanied by noise and vibration.
Cavitation damage Damage caused when partial vacuums formed in a liquid by a swiftly moving solid body (e.g. a propeller) pit and wear away solid surfaces (e.g. metal or concrete). The attack on surfaces caused by the implosion of bubbles of water vapor.
Cellular gravity dam See hollow gravity dam.
Certified water right A State-issued document that serves as legal evidence that an approved application has been physically developed and the water put to beneficial use. The certificate establishes: priority date, type of beneficial use, and the maximum amount of water that can be used. Verification must be provided to the State through a survey conducted by an approved water-rights examiner. Even certified rights are subject to occasional review to ensure continued beneficial use.