A berm is a wall or mound of dirt that keeps rainwater within a defined area. Used with retention grading, berms reduce runoff and create a temporary water storage area.
How to create a berm
Berms are typically located around a lawn or garden area or at the base of the property. Consider if you have an area of your property that can use a berm along its edges to prevent water flowing onto the driveway, sidewalk or street. Note that before implementing this infiltration technique, it is highly recommended to determine the soil permeability.
- Pile dirt up using soil from either the surrounding landscape or purchase topsoil. Use the topsoil formula to determine how much you need.
- Compact the berm by jumping up and down on it and tamping it down well. This will ensure it doesn’t wash away when it rains.
- Plant the berm using drought-tolerant shrubs and groundcover.
- Cover any exposed soil with a 3 to 4-inch layer of mulch to prevent the soil from drying out and eroding.
How much topsoil do I need?
Measure the different areas that need berms, in feet. Use the formula below to figure the amount of topsoil needed in cubic yards.
- Multiply the width by the height of the berm: (width in ft) X (height in ft.) = (area in sq. ft.)
- Multiply the area by the length of the berm: (area in sq. ft.) X (length in ft) = (cubic ft)
- For cubic yards, divide by 27: (cubic ft) ÷ 27 = (cubic yards)
- Add together the amount needed for all areas of the property.
- Total amount of topsoil needed: _______ cubic yards
Is this practice right for you?
Consult a professional if you're not sure. Also, see our web pages discussing maintenance issues, costs and other factors.