#GBSB1609 Gravel Bags vs Sand Bags
BMP Factsheet (SE-6) (SE-4)
Gravel Bag and Sand Bag are not interchangeable terms. There are some key differences between the two, and unique uses for each. Using the proper BMP for a situation is crucial for the success of the BMP; using the wrong BMP can lead to failures and actually cause more damage
Gravel bags are used to filter sediment laden water. They are used to slow the flow of water, and allow slight ponding of water so sediment can settle out of solution.
Gravel bags also impede water and slow its velocity and are appropriate for most common circumstances such as; chevrons/check dams, drain inlet protection, and other various water slowing measures.
The materials gravel bags are constructed out of are crucial to its efficiently. Gravel bags that are made with plastic prevent a large amount of water running through it and thereby causes ponding and eventually may overwhelm the BMP. A far better alternative are gravel bags made from a burlap material.
Burlap Bags provide better filtering for the water while still allowing water to flow through the barrier due to its porous design.
Sand bags are used to stop or divert water from flowing in a certain direction. They are designed to allow water to pool behind them and are often implemented as check dams, linear barriers, means of flood control, and channeling water.
Sand bags have a more limited use than gravel bags do, and may be completely unnecessary on most construction sites. These bags may be used on an edge of a construction site where there is concern about water breaching a perimeter point or on the edge of a driveway to prevent any sediment laden water from entering a street.
In addition, sandbags exposed to sunlight will need to be replaced every two to three months due to degradation of the bags. Also, sandbags should not be used in rivers or streams, as a broken sandbag will leak sand and thereby should never be put into or adjacent to a stream, even if encapsulated in a geotextile.
Despite what bag is being used on site, all bags need to be maintained by replacing old broken bags.
When you’re choosing which bag to implement on your site, refer to the SWPPP Map.