Aberm is a level space, shelf, or raised barrier (usually made ofcompacted soil) separating areas in a vertical way, especially partway up a long slope. It can serve as a terrace road, track, path, afortification line, aborder/separation barrier for navigation, good drainage, industry, or other purposes. It can also be used on hunting property.[1] For general applications, a berm is a physical, stationary barrier of some kind.
The word is fromMiddle Dutch and came into usage in English via French.[2] In coastal geography, aberm is a bank of sand or gravel ridge parallel to the shoreline and a few tens of centimetres high, created by wave action throwing material beyond the average level of the sea. Berms are also used as a method of environmental spill containment and liquid spill control.
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Inmedievalmilitary engineering, a berm (or berme) was a level space between aparapet ordefensive wall and an adjacent steep-walledditch ormoat.[2] It was intended to reducesoilpressure on the walls of the excavated part to prevent its collapse. It also meant that debris dislodged from fortifications would not fall into (and fill) a ditch ormoat.
In thetrench warfare ofWorld War I, the name was applied to a similar feature at the lip of atrench, which served mainly as an elbow-rest forriflemen.
In modern military engineering, a berm is the earthen orsodwall or parapet, especially a low earthen wall adjacent to a ditch. The digging of the ditch (often by abulldozer ormilitary engineering vehicle) can provide the soil from which the berm is constructed. Walls constructed in this manner are an obstacle tovehicles, including mostarmoured fighting vehicles but are easily crossed byinfantry. Because of the ease ofconstruction, such walls can be made hundreds or thousands of kilometres long. A prominent example of such a berm is the 2,700 km (1,700 mi)Moroccan Western Sahara Wall.
Berms are also used to control soilerosion andsedimentation by reducing the rate ofsurface runoff. The berms either reduce thevelocity of thewater, or direct water to areas that are not susceptible to erosion, thereby reducing the adverse effects of running water on exposedtopsoil. Following the 2010Deepwater Horizon oil spill in the Gulf of Mexico, the construction of berms designed to prevent oil from reaching the fragileLouisianawetlands (which would result in massive erosion) was proposed early on, and was officially approved by thefederal government in mid-June, 2010, after numerous failures to stop and contain the oil leak with more advanced technologies.[3]
Earth is piled up against exterior walls and packed, sloping down away from the house. The roof may or may not be fully earth covered, and windows/openings may occur on one or more sides of the shelter. Due to the building being above ground, fewer moisture problems are associated with earth berming in comparison to underground/fully recessed construction.
Inhighway construction, a berm is anoise barrier constructed of earth, oftenlandscaped, running along a highway to protect adjacent land users fromnoise pollution. The shoulder of a road is also called a berm and in New Zealand the word describes a publicly owned grassed nature strip sometimes planted with trees alongside urban roads (usually called a verge).[4][5] Insnowboard cross, a berm is a wall ofsnow built up in a corner.[6] Inmountain biking, a berm is a banked turn formed by soil, commonly dug from the track, being deposited on the outer rim of the turn. Incoastal systems, a berm is a raised ridge ofpebbles orsand found at hightide orstorm tide marks on abeach. In snow removal, a berm orwindrow refers to the linear accumulation of snow cast aside by aplow.[7] Earth berms are used above particle accelerator tunnels to provide shielding from radiation.[8] Inopen-pit mining, a berm refers to dirt androck piled alongside ahaulage road or along the edge of a dump point. Intended as a safety measure, they are commonly required by government organizations to be at least half as tall as the wheels of the largestmining machine on-site.[9][10]
Physical security systems employ berms to exclude hostile vehicles and slow attackers on foot (similar to the military application without the trench). Security berms are common around military and nuclear facilities. An example is the berm proposed forVermont Yankee nuclear power plant in Vermont.[11] AtBaylor Ballpark, a baseball stadium on the campus ofBaylor University, a berm is constructed down the right field line. The berm replaces bleachers, and general admission tickets are sold for fans who wish to sit on the grass or watch the game from the top of the hill.
Bunding is the construction of a secondary impermeable barrier around and beneath storage or processing plant, sufficient to contain the plant's volume after a spill. This is often achieved on large sites by surrounding the plant with a berm. The USEnvironmental Protection Agency (EPA) requires that oils and fuels stored over certain volume levels be placed in secondary spill containment. Berms for spill containment are typically manufactured frompolyvinyl chloride (PVC) orgeomembrane fabric that provide a barrier to keep spills from reaching the ground or navigable waterways. Most berms have sidewalls to keep liquids contained for future capture and safe disposal.
The shoulder of a road.
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