A berm is a level space, shelf, or raised barrier (usually made of

compacted soil In geotechnical engineering, soil compaction is the process in which stress applied to a soil causes densification as air is displaced from the pores between the soil grains. When stress is applied that causes densification due to water (or other ...

) separating areas in a vertical way, especially partway up a long slope. It can serve as a terrace road, track, path, a

fortification line A defense line or fortification line is a geographically-recognizable line of troops and armament, fortified and set up to protect a high-value location or defend territory. A defense line may be based on natural difficult terrain features, su ...

, a

border Borders are usually defined as geographical boundaries, imposed either by features such as oceans and terrain, or by political entities such as governments, sovereign states, federated states, and other subnational entities. Political borders c ...

separation barrier A separation barrier or separation wall is a barrier, wall or fence, constructed to limit the movement of people across a certain line or border, or to separate peoples or cultures. A separation barrier that runs along an internationally recogni ...

for navigation, good drainage, industry, or other purposes.

Etymology

The word is one of Middle Dutch and came into usage in English via French.

Military use

History

medieval In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the Post-classical, post-classical period of World history (field), global history. It began with t ...

military engineering, a berm (or berme) was a level space between a

parapet A parapet is a barrier that is an extension of the wall at the edge of a roof, terrace, balcony, walkway or other structure. The word comes ultimately from the Italian ''parapetto'' (''parare'' 'to cover/defend' and ''petto'' 'chest/breast'). Whe ...

defensive wall A defensive wall is a fortification usually used to protect a city, town or other settlement from potential aggressors. The walls can range from simple palisades or earthworks to extensive military fortifications with towers, bastions and gates ...

and an adjacent steep-walled ditch or

moat A moat is a deep, broad ditch, either dry or filled with water, that is dug and surrounds a castle, fortification, building or town, historically to provide it with a preliminary line of defence. In some places moats evolved into more extensive ...

. It was intended to reduce

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...

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 or

. In the

trench warfare Trench warfare is a type of land warfare using occupied lines largely comprising military trenches, in which troops are well-protected from the enemy's small arms fire and are substantially sheltered from artillery. Trench warfare became a ...

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, the name was applied to a similar feature at the lip of a

trench A trench is a type of excavation or in the ground that is generally deeper than it is wide (as opposed to a wider gully, or ditch), and narrow compared with its length (as opposed to a simple hole or pit). In geology, trenches result from eros ...

, which served mainly as an elbow-rest for riflemen.

Modern usage

In modern military engineering, a berm is the earthen or

sod Sod, also known as turf, is the upper layer of soil with the grass growing on it that is often harvested into rolls. In Australian and British English, sod is more commonly known as ''turf'', and the word "sod" is limited mainly to agricult ...

wall A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or, is decorative. There are many kinds of walls, including: * Walls in buildings that form a fundamental part of the supe ...

or parapet, especially a low earthen wall adjacent to a ditch. The digging of the ditch (often by a

bulldozer A bulldozer or dozer (also called a crawler) is a large, motorized machine equipped with a metal blade to the front for pushing material: soil, sand, snow, rubble, or rock during construction work. It travels most commonly on continuous track ...

or military engineering vehicle) can provide the soil from which the berm is constructed. Walls constructed in this manner are an obstacle to

vehicle A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), wa ...

s, including most armoured fighting vehicles but are easily crossed by

infantry Infantry is a military specialization which engages in ground combat on foot. Infantry generally consists of light infantry, mountain infantry, motorized infantry & mechanized infantry, airborne infantry, air assault infantry, and marine i ...

. Because of the ease of

construction Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and com ...

, such walls can be made hundreds or thousands of kilometres long. A prominent example of such a berm is the Moroccan Western Sahara Wall.

Erosion control

Berms are also used to control

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

and

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...

ation by reducing the rate of

surface runoff Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when th ...

. The berms either reduce the

velocity Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a ...

of the

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

, or direct water to areas that are not susceptible to erosion, thereby reducing the adverse effects of running water on exposed

topsoil Topsoil is the upper layer of soil. It has the highest concentration of organic matter and microorganisms and is where most of the Earth's biological soil activity occurs. Description Topsoil is composed of mineral particles and organic matt ...

. Following the 2010 ''Deepwater Horizon'' oil spill in the Gulf of Mexico, the construction of berms designed to prevent oil from reaching the fragile

Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...

wetlands A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

(which would result in massive erosion) was proposed early on, and was officially approved by the

federal government A federation (also known as a federal state) is a political entity characterized by a union of partially self-governing provinces, states, or other regions under a central federal government (federalism). In a federation, the self-governin ...

in mid-June, 2010, after numerous failures to stop and contain the oil leak with more advanced technologies.

Geography

In coastal geography, a berm 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.

House construction

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.

Other applications

Spill berms for secondary containment requirements

For general applications, a berm is a physical, stationary barrier of some kind. For example, in modern

highway A highway is any public or private road or other public way on land. It is used for major roads, but also includes other public roads and public tracks. In some areas of the United States, it is used as an equivalent term to controlled-access ...

construction, a berm is a

noise barrier A noise barrier (also called a soundwall, noise wall, sound berm, sound barrier, or acoustical barrier) is an exterior structure designed to protect inhabitants of sensitive land use areas from noise pollution. Noise barriers are the most effecti ...

constructed of earth, often

landscaped Landscape architecture is the design of outdoor areas, landmarks, and structures to achieve environmental, social-behavioural, or aesthetic outcomes. It involves the systematic design and general engineering of various structures for constructio ...

, running along a highway to protect adjacent land users from

noise pollution Noise pollution, also known as environmental noise or sound pollution, is the propagation of noise with ranging impacts on the activity of human or animal life, most of them are harmful to a degree. The source of outdoor noise worldwide is main ...

. The shoulder of a road is also called a berm and in New Zealand the word sometimes describes a publicly owned grassed nature strip sometimes planted with trees alongside urban roads (usually called a verge)

In

snowboard cross Snowboard cross, also known as boardercross, is a snowboard competition in which four to six competitors race down a course. Snowboard cross courses are typically quite narrow and include cambered turns, various types of jumps, berms, rollers, ...

, a berm is a wall of

snow Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout ...

built up in a corner. In

mountain biking Mountain biking is a sport of riding bicycles off-road, often over rough terrain, usually using specially designed mountain bikes. Mountain bikes share similarities with other bikes but incorporate features designed to enhance durability and pe ...

, a berm is a banked turn formed by soil, commonly dug from the track, being deposited on the outer rim of the turn. In coastal systems, a berm is a raised ridge of

pebble A pebble is a clast of rock with a particle size of based on the Udden-Wentworth scale of sedimentology. Pebbles are generally considered larger than granules ( in diameter) and smaller than cobbles ( in diameter). A rock made predominant ...

s or

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of s ...

found at high

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravity, gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide t ...

or storm tide marks on a

beach A beach is a landform alongside a body of water which consists of loose particles. The particles composing a beach are typically made from rock, such as sand, gravel, shingle, pebbles, etc., or biological sources, such as mollusc shel ...

. In snow removal, a berm or

windrow A windrow is a row of cut (mown) hay or small grain crop. It is allowed to dry before being baled, combined, or rolled. For hay, the windrow is often formed by a hay rake, which rakes hay that has been cut by a mowing machine or by scythe into a ...

refers to the linear accumulation of snow cast aside by a

plow A plough or plow ( US; both ) is a farm tool for loosening or turning the soil before sowing seed or planting. Ploughs were traditionally drawn by oxen and horses, but in modern farms are drawn by tractors. A plough may have a wooden, iron or ...

. Earth berms are used above particle accelerator tunnels to provide shielding from radiation. In

open-pit mining Open-pit mining, also known as open-cast or open-cut mining and in larger contexts mega-mining, is a surface mining technique of extracting rock or minerals from the earth from an open-air pit, sometimes known as a borrow. This form of mining ...

, a berm refers to dirt and

rock Rock most often refers to: * Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids * Rock music, a genre of popular music Rock or Rocks may also refer to: Places United Kingdom * Rock, Caerphilly, a location in Wales ...

piled alongside a haulage 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 largest

mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic via ...

machine on-site. 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 for

Vermont Yankee nuclear power plant Vermont Yankee was an electricity generating nuclear power plant, located in the town of Vernon, Vermont, in the northeastern United States. It generated 620 megawatts (MWe) of electricity at full power. The plant was a boiling water reacto ...

in Vermont. At

Baylor Ballpark Baylor Ballpark is the baseball stadium at Baylor University in Waco, Texas. The stadium was built on the site of Ferrell Field, Baylor's home from 1977 to 1998, by mid-February in 1999. The Bears have hosted three NCAA regional and two super regi ...

, a baseball stadium on the campus of

Baylor University Baylor University is a private Baptist Christian research university in Waco, Texas. Baylor was chartered in 1845 by the last Congress of the Republic of Texas. Baylor is the oldest continuously operating university in Texas and one of the fir ...

, 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. Berms are also used as a method of environmental spill containment and liquid spill control. 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 US

Environmental Protection Agency A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale f ...

(EPA) requires that oils and fuels stored over certain volume levels be placed in secondary spill containment. Berms for spill containment are typically manufactured from polyvinyl chloride (PVC) or

geomembrane A geomembrane is very low permeability synthetic membrane liner or barrier used with any geotechnical engineering related material so as to control fluid (liquid or gas) migration in a human-made project, structure, or system. Geomembranes are ...

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.

References

External links

{{Authority control Archaeological features Artificial landforms Fortification (architectural elements) Fortification lines Snow removal