A filter berm is a temporary ridge made up of loose gravel, stone, or crushed rock.
Understanding Filter Berms
Filter berms are simple but effective structures used primarily on construction sites or disturbed areas. They are designed as temporary measures to manage water flow and prevent sediment from leaving the site.
Materials
As described, a filter berm is constructed using readily available, coarse granular materials:
- Loose gravel
- Stone
- Crushed rock
These materials are piled to form a ridge or berm across the path of runoff.
How it Functions
The primary functions of a filter berm are based on its design and materials:
- Slows and filters flow: The porous nature of the gravel or stone allows water to pass through slowly. As water percolates, sediment and suspended solids are trapped within the berm materials, filtering the runoff.
- Diverts flow: The physical ridge can also direct water flow away from sensitive areas, such as open traffic lanes or waterways, ensuring it passes through the filtering material.
Purpose: Sediment Control
Ultimately, the action of slowing, filtering, and diverting water makes the filter berm an efficient form of sediment control. By capturing sediment close to its source, filter berms help protect downstream environments from pollution and comply with erosion control regulations.
