Civil engineer guide to fighting positions, shelters, obstacles

AFH 10-222 Volume 14 1 August 2008 101
5.2.1. Free-Standing Berms. When designing free-standing berms, key elements
to consider are height, thickness, and slope. Also keep in mind the
need to use natural vegetation, geotextile fabric, and/or a drainage system to
prevent erosion. If camouflage and concealment are important, consider adding
more vegetation and varying the berm’s width and height along the perimeter
to reduce its visual signature. The next few paragraphs cover basic
considerations for designing and constructing free-standing berms.
5.2.1.1. Berm Height. Berm heights (Figure 5.2) are usually determined by
the height of the asset(s) to be protected. If the asset to be protected is 6 feet
tall, the berm will need to be at least that height for adequate protection.
Figure 5.2. Berm Height.
5.2.1.2. Berm Thickness. Required thickness is usually determined by the
desired level of protection for the asset(s) and any known threats. Security
and Intelligence personnel will be involved in making this determination. A
berm’s thickness is measured at its crest (Figure 5.3), which is where the
slope of the berm levels off. A small slope is still maintained at the crest to
allow for drainage and prevent ponding. If the berm’s required thickness is
determined to be 36 inches, the berm must be 36 inches thick at its crest.
Attachment 2 contains information on various thicknesses of materials
needed to protect against certain threats. For practical purposes (e.g., maintenance),
the crest of a free-standing berm is usually between 2 and 3 feet.
Figure 5.3. Berm Thickness.