NPDP Dam Dictionary

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Term AKA Definition
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.
Coordinated operation Generally, the operation of two or more interconnected electrical systems to achieve greater reliability and economy. As applied to hydropower resources, the operation of a group of hydropower plants to obtain optimal power benefits with due consideration to all other uses.
Corduroy A road made of logs laid crosswise on the ground or on other logs.
Core Impervious core; Impervious zone A zone of material of low permeability in an embankment dam. Hence the expressions central core inclined core puddle clay core and rolled clay core." A cylindrical piece of an underground formation cut and raised by a rotary drill with a hollow bit."
Core drill A rotary drill, usually a diamond drill, equipped with a hollow bit and a core lifter.
Core wall A wall of substantial thickness built of impervious material, usually of concrete or asphaltic concrete in the body of an embankment dam to prevent leakage. See membrane.
Correlation The relation between two or more variables. A statistical test that sets a numerical value to the amount of interdependence.
Corridor Narrow strip of land reserved for location of transmission lines, pipelines, and service roads.
Corrosion Wear or dissolving away through chemical action as by rusting, or acids.
Cost effectiveness Economic efficiency, obtaining the best method for the least amount of money.
Coulees Small streams or dry streambeds.
County The name of the county in which the dam is located.
Coyote holes Horizontal tunnels in which explosives are packed for blasting a high rock face.