Dewatering Silt Bags
Temporary Sediment Basin for Filtration
Question: I was looking at your dewatering silt bags and I was wondering if you have ever heard of using a large filter bag in place of a temporary sediment basin? The project that I am working on requires a temporary sediment basin at every outfall. The area for these basins is not very large and would require cleaning a lot of wooded areas. Could I use a large filter bag in place of this basin to settle out sediment? I would pump the discharge through the bag.
Answer: Choosing the correct BMP or pollution control device for your location can depend on a lot of different factors including available space, the amount of needed sediment control, and various local regulations.
In general, Dewatering Bags are a favorite for construction sites and have frequently been used in projects to help filter out silt and sediment before it flows into a drain. They are designed to retain silt and sediment that enters the bag, while still allowing clean water to flow out.
If you do connect the sediment laden water directly to the dewatering bag, this system might be able to work in your location. Through this connection, bags would then be in contact with all the water that is flowing from your systems, and would allow the sediment and harmful materials within your system to be appropriately filtered out.
Standard Dewatering Bag Sizing
- 6' x 6'
- 15' x 10'
- 15' x 15'
- 15' x 20'
- 15' x 25'
Flow rates will vary depending on whether you use an 8 ounce or 10 ounce material. Eight ounce (8 oz.) fabric has a standard filtering rate of 80 gpm/sq. ft., while the ten ounce (10 oz.) fabric filters at approximately 60 gpm/sq.ft.
Additional Sediment Filtration Considerations
In order to determine if this bag would work in your location, customers are typically asked to consider the following:
- How much water will be pumped into the bag?
- What is the pump flow rate?
- What is the type of sediment that needs to be contained?
- How much of this sediment is present?
- How much permittivity does your desired bag need?
If you are considering these dewatering silt bags and find that even the largest size might be too small, you might also consider the Geotextile Tube. These units are significantly larger in size and can be used for large sludge or dewatering projects.