Berm 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 . Military use . History . In medieval military engineer ing , a berm ( or berme ) was a level space between a parapet or defensive wall and an adjacent steep - walled ditch or moat . 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 vehicle s , 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 sediment ation 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 . 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 . Berm has been adopted as a wider term usually used to describe a physical , stationary barrier of some kind . For example in modern highway construction , a berm is a noise barrier constructed of earth , often landscaped , running along a highway to protect adjacent land users from noise pollution . In Snowboard Cross , a berm is a wall of snow built up in a corner . In Mountain biking , 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 s or sand found at high tide or storm tide marks on a beach . In snow removal , a berm or windrow refers to the linear accumulation of snow cast aside by a plow . In open - pit mining , a berm refers to dirt and rock 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 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 in Vermont . 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 .