Technical Manual: Conduits through Embankment Dams (FEMA 484)

Conduits through Embankment DamsRadiography: A nondestructive testing method that provides an internalexamination of a metallic structure or component by exposing it to a beam of X-rayor gamma radiation. Internal defects can be seen on a screen or recorded on film.Regulating gate: See Gate, regulating.Reinforced cast-in-place concrete: See Concrete, reinforced cast-in-place.Reinforcement (ASTM C 822, 2002): Steel in the form of continuous wire, weldedwire fabric, or bars embedded in concrete in such a manner that the concrete andsteel act together to resist stresses.Relative density: A numerical expression that defines the relative denseness of acohesionless soil. The expression is based on comparing the density of a soil mass ata given condition to extreme values of density determined by standard tests thatdescribe the minimum and maximum index densities of the soil. Relative density isthe ratio, expressed as a percentage, of the difference between the maximum indexvoid ratio and any given void ratio of a cohesionless, free-draining soil; to thedifference between its maximum and minimum index void ratios.Remotely operated vehicle (ROV): An unoccupied, highly maneuverableunderwater robot controlled by a remote operator usually located in a ship or on theshore. Most vehicles are equipped with a video camera and lights. Additionalequipment can be added to expand the vehicle’s capabilities.Renovation: The repair or restoration of an existing structure, so it can serve itsintended purpose.Repair: The reconstruction or restoration of any part of an existing structure for thepurpose of its maintenance.Replacement: The removal of existing materials that can no longer perform theirintended function and installation of a suitable substitute.Reservoir (FEMA, 2004): A body of water impounded by an embankment damand in which water can be stored.Reservoir evacuation: The release or draining of a reservoir through an outletworks, spillway, or other feature at an embankment dam.Resin (ASTM F 412, 2001): A solid or pseudosolid organic material, often withhigh molecular weight, which exhibits a tendency to flow when subjected to stress,usually has a softening or melting range, and usually fractures conchoidally (shell-likefracture).412