Glossary

The property of soil or rock thatallows passage of water through it.

A document issued by the Department of the Army expressing the assent of the Federal Government, so far as concerns the public rights of navigation and the general public interest, for the accomplishment of certain works on or adjacent to navigable waters of the United States.

A long, heavy timber or section of concrete or metal to be driven or jetted into the earth or lakebed to serve as a support or protection.

A pile with a generally slender flat cross section to be driven into the ground or lakebed and meshed or interlocked with like members to form a diaphragm, wall, or bulkhead.

Powerhouses are often constructed as an intergral part of a dam, especially high head dams, to provide for the generation of electricity from the hydraulic head provided by the dam. The powerhouse consists of a penstock which transports the water to a turbine, generators and transmission lines which transport the electricity to the grid.

The most severe floodthat may be expected from a combination of themost critical meteorological and hydrologicalconditions that are reasonably possible in thedrainage basin. It is used in designing high-riskflood protection works and siting of structures andfacilities that must be subject to almost no risk offlooding. The probable maximum flood is usuallymuch larger than the 100-year flood.

A graph or plot of the water surfaceelevation against distance along a channel. Alsotermed 'flood profile' if drawn for a specific floodor level of flooding.

Pumping stations are used to pump interior flood waters into the river during flood conditions when gravity outlets to the river are closed. Floodwater pumping stations pump directly from open storage ponds, ditches, or storm water sewers. Pump stations may contain either vertical pumps or submersible pumps.

Aesthetic consideration in the design of pump stations incorporating similar or complementing architectural style of the community or region using materials and characteristic of that style.

A gatewell structure is either a cast-in place or precast concrete box type structure usually placed on the river side of a levee. The gatewell contains a gate to control discharges from the interior side of the levee through a pipe at the base of the levee to the river side of the levee. The gate is usually open during gravity or non-flood conditions and closed during flood conditions which require use of a pumping facility to evacuate the interior flooding.

Submersible pumps have the electric motor close coupled to the pumping element with the entire pumping unit being submerged in water. Submersible pumps are considered for stations that have pumping requirements with each pump having a capacity less than 6 m3/s (200 cfs) These types of pumps should be removable from above the floor without any unbolting of the discharge piping. Their use allows the superstructure of the station to be greatly reduced. Substructure requirements are approximately the same as for vertical pumps.

Vertical pumps are most commonly used in flood-risk management pumping stations. . A vertical pump has a vertical shaft with the driver having a vertical or horizontal shaft arrangement. A vertical motor is usually directly connected to the pump.