NPDP Dam Dictionary

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Term AKA Definition
Common material All earth materials which do not fall under the definition of rock.
Compacted backfill Backfill which has been reduced to bulk by rolling, tamping, or soaking.
Compacted embankment Embankment which has been reduced in bulk by rolling, tapping, or soaking.
Compaction To make soil dense by mechanical manipulation. See dumped, dynamic compaction, jetting, ponding, puddling, rolling, saturation, sluicing, surface vibration, and tamping.
Compaction curve Proctor curve; Moisture-density curve The curve showing the relationship between the dry density and the water content of a soil for a given compactive effort.
Compressibility Property of a soil describing its susceptibility to decrease in volume when subjected to load.
Concrete dam See arch dam, buttress dam, or gravity dam. See also masonry dam.
Concrete lift In concrete work, the vertical distance between successive horizontal construction joints.
Conduit Covered portion of spillway between the gate or crest structure and the terminal structure, where open channel flow and/or pressure flow conditions may exist. Portion of an outlet works between the intake structure and gate chamber and/or the control structure. Conduits are located beneath embankment dams and within concrete dams. Conduits are concrete lined or concrete/steel lined. A pipe, box, or horseshoe structure, or natural channel that is constructed by means of cut and cover". A conduit can convey water or house other conduits or pipes. "
Consequence Type Type of the consequence that might have resulted from a dam incident. Examples include fatalities, injuries, property damages, etc.
Consolidation grouting Strengthening an area of ground by injecting grout.
Constant angle arch dam An arch dam in which the angle subtended by any horizontal section is constant throughout the whole height of the dam.
Constant radius arch dam An arch dam in which every horizontal segment or slice of the dam has approximately the same radius of curvature.
Construction joint Construction joints are purposely placed in concrete to facilitate construction; to reduce initial shrinkage stresses and cracks; to allow time for the installation of embedded metalwork; or to allow for the subsequent placing of other concrete. Bond is required at construction joints regardless of whether or not reinforcement is continuous across the joint. A construction joint allows a reasonable size concrete placement or a point to terminate a placement. The interface between two successive placings of concrete where bond, and not permanent separation, is intended.
Consumer surplus The value of a commodity, good, or opportunity above the cost to the consumer; measured using willingness to pay, as specified in Federal guidelines for water resources planning.
Consumptive use A use which lessens the amount of water available for another use. Water uses normally associated with man's activities, primarily municipal, industrial, and irrigation uses that deplete water supplies. A nonconsumptive use would be one such as boating or swimming. See beneficial use.
Consumptive water use Total amount of water used by vegetation, man's activities, and evaporation of surface water.
Contact grouting Filling, with cement grout, any voids existing at the contact of two zones of different materials, e.g., between a concrete tunnel lining and the surrounding rock. The grout operation is usually carried out at low pressure.
Containment levee A dike or embankment to contain stream flow.
Contiguous Actual contact with; also, near or adjacent to.
Contingencies Used in appraisal and feasibility estimates to estimate overruns on quantities, changed site conditions, change orders, etc. Contingencies are considered as funds to be used after construction starts and not for design changes or changes in project planning. Appraisal estimates should have 25 percent added and feasibility estimates should have 20 percent added for contingencies.
Contingent valuation Survey method asking for the maximum values that recreationists would pay for access to a particular activity.
Contour A line of constant elevation.
Contract rate The repayment or water service rate set forth in a contract to be paid by a district to the United States.
Contraction joint Contraction joints are placed in concrete to provide for volumetric shrinkage of a monolithic unit or movement between monolithic units. Contraction joints have no bond between the concrete surfaces forming the joint. Except as otherwise provided for dowels, reinforcement is never continuous across a contraction joint. Contraction joints will not transfer moment and will not transfer shear unless keyed.
Control area Part of a power system, or a combination of systems, to which a common electrical generation allocation scheme is applied.
Control house See control structure.
Control joint Control joints are joints placed in concrete to provide for control of initial shrinkage stresses and cracks of monolithic units. Control joints are similar to contraction joints except that reinforcement is always continuous across the joint. Control joints are unbonded joints to provide weak areas for cracking. Control joints will transfer moment, but will not transfer shear unless keyed.
Control structure Control house Concrete portion of an outlet works, located at the downstream end of the tunnel or conduit, housing the control (regulation) gates.
Conveyor. A device that transports material by belts, cables, or chains.