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Berm

 

Berm

Embankment dam with two berms

A berm is a level space, shelf, or raised barrier separating two areas. It can serve as a border barrier. The word berm originates in the Middle Dutch and German berme and came into usage in English via French.[1]

Contents

  • Military use 1
    • History 1.1
    • Modern usage 1.2
  • Erosion control 2
  • House construction 3
  • Uses in other applications 4
  • See also 5
  • References 6
  • External links 7

Military use

History

In medieval military engineering, a berm (or berme) was a level space between a parapet or defensive wall and an adjacent steep-walled ditch or moat.[1] It was intended to reduce soil pressure 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 moat.

In the trench warfare of World War I, the name was applied to a similar feature at the lip of a trench, which served mainly as an elbow-rest for riflemen.

Modern usage

In modern military engineering, berm has come to mean the earthen or sod wall or parapet itself. The term especially refers to a low earthen wall adjacent to a ditch. The digging of the ditch (often by a bulldozer or military engineering vehicle) can provide the soil from which the berm is constructed. Walls constructed in this manner are an effective obstacle to vehicles, including most armoured fighting vehicles, but are easily crossed by infantry. Because of the ease of construction, such walls can be made hundreds or thousands of kilometres long.

Erosion control

Berms are also used to control erosion and sedimentation by reducing the rate of surface runoff. The berms either reduce the velocity of the water, or direct water to areas that are not susceptible to erosion, thereby reducing the adverse effects of running water on exposed topsoil. 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 wetlands (which would result in massive erosion) was proposed early on, and was officially approved by the federal government in mid-June, 2010, after numerous failures to stop and contain the oil leak with more advanced technologies.[2]

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.

Uses in other applications

A typical berm application

Berm has been adopted as a wider term usually used to describe a physical, stationary barrier of some kind. For example in modern mining machine on-site.[6][7]

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 in Vermont.[8] At Baylor Ballpark, a baseball stadium on the campus of Baylor 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.

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 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 PVC or geomembrane 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.[9]

See also

References

  1. ^ a b Oxford English Dictionary. Oxford, England: Oxford University Press. 1989. 
  2. ^ the CNN Wire Staff (2010-06-03). "'Top Kill' fails, BP moves on 'to next option.'". Cnn.com. Retrieved 2010-06-23. 
  3. ^ "berm also berme, n., def. 1.b". American Heritage Dictionary of the English Language (3rd ed.). Boston & New York: Houghton Mifflin. 1992.  
  4. ^ Pro Snowboarder. "EXPN.com BMX Glossary". Expn.go.com. Retrieved 2010-06-23. 
  5. ^ Glossary of Snow and Ice Control Terms
  6. ^ "Mine Safety and Health Administration (MSHA) - Interactive Training - Surface Powered Haulage Safety". Msha.gov. Retrieved 2010-06-23. 
  7. ^ "Microsoft PowerPoint - DumpPointSafety.ppt [Read-Only]" (PDF). Retrieved 2010-06-23. 
  8. ^ http://www.state.vt.us/psb/orders/2006/files/7082orderrerecon.pdf
  9. ^ http://www.aireindustrial.net

External links

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