NPDP Dam Dictionary

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Term AKA Definition
Face Exposed surface of dam materials (earth, rockfill, or concrete), upstream and downstream. The external surface which limits the structure, see neatlines. The more or less vertical surface of rock exposed by blasting or excavating. The cutting end of a drill hole.
Facilities Structures associated with Reclamation irrigation projects, municipal and industrial water systems, power generation facilities, including all storage, conveyance, distribution, and drainage systems.
Facing With reference to a wall or concrete dam, a coating of a different material, masonry or brick, for architectural or protection purposes, e.g., stonework facing, brickwork facing. With reference to an embankment dam, an impervious coating or face on the upstream slope of the dam.
Factor of safety The ratio of the ultimate strength of the material to the allowable or working stress.
Fallow Land plowed and tilled and left unplanted.
False set See horsehead.
Fatality Injury Description Describe where or how fatalities and injuries occurred.
Fault A fracture in rock along which the adjacent rock surfaces are differentially displaced.
Fault A shear with significant continuity that can be correlated between observation points.
Faulting The movement which produces relative displacement along a fracture in rock.
Fauna All animals associated with a given habitat, country, area, or period.
Feasibility estimate An estimate used for determining the economic feasibility of a project, the probable sequence and cost for construction of a project, and as a guide in the choice between alternative locations or plans.
Feather To blend the edge of new material smoothly into the old surface.
Fill Manmade deposit of natural soils or the process of the depositing. An earth or broken rock structure or embankment. Soil or loose rock used to raise a grade. Soil that has no value except as bulk
Filter filter zone A band of granular material which is incorporated in an embankment dam and is graded (either naturally or by selection) so as to allow seepage to flow across or down the filter zone without causing the migration of the material from zones adjacent to the filter.
Filter cake Mud cake A deposit of mud on the walls of a drill hole.
Financial analysis Procedure that considers only tangible factors when evaluating various alternatives.
Fines Portion of a soil finer that a No. 200 U.S. Standard sieve. Clay or silt particles in soil.
Finger drains A series of parallel drains of narrow width (instead of a continuous drainage blanket) draining to the downstream toe of the embankment dam.
Finished grade The elevation or surface of the earth after all earthwork has been completed (also finish grade). The final grade required by specifications.
Firm energy Power Non-interruptible energy and power guaranteed by the supplier to be available at all times, except for uncontrollable circumstances.
Fish ladder Fishway An inclined trough which carries water from above to below a dam so that fish can easily swim upstream. There are various types, some with baffles to reduce the velocity of the water and some consisting of a series of boxes with water spilling down from one to the next.
Fish weir A type of fish ladder.
Fishing The operation of recovering an object left or dropped in a drill hole.
Fixed-wheel gate A gate consisting of a rectangular leaf mounted on wheels, particularly suited for high head situations.
Flail A hammer hinged to an axle so that is can be used to break or crush material.
Flange A ridge that prevents a sliding motion. A rib or rim for strength or for attachments.
Flashboards Temporary barriers, consisting of either timber, concrete or steel, anchored to the crest of a spillway as a means of increasing the reservoir storage. Flashboards can be removed, lowered, or carried away at the time of flooding either by a tripping device or by deliberate failure of the flashboards or their supports.
Flat slab Slab and buttress dam A buttress dam with buttresses which support the flat slab of reinforced concrete which forms the upstream face.
Fleet angle The angle between the position of a rope or cable at the extreme end wrap on a drum and a line drawn perpendicular to the axis of the drum. The fleet angle is used to indicate how effective or efficient the rope or cable is for raising a load.