.png?width=185&height=175&name=WGI%20Icon_Green%20(1).png)
If you work in construction, you know the importance of Temporary Sediment Basins. These basins are essential for keeping our water clean and free of pollutants, which can hugely affect the environment and nearby communities.
But what exactly are Temporary Sediment Basins, and when are they required?
Image Source: Tennessee Department of Environment & Conservation[/caption]
Sediment settles out of the water while it is held in the basin, reducing the negative impact on water quality that construction sites can typically cause. The image to the right displays an example of a typical Sediment Basin.
There are several drawings and calculations that need to be submitted for review by the authority with jurisdiction over the project, as well as the TCEQ (Texas Commission on Environmental Quality), as part of the contractor’s application for coverage under the state’s general permit.
What are they?
Temporary Sediment Basins are interim ponds that serve the purpose of both capturing and treating stormwater runoff during construction prior to releasing the water back into the drainage system. By capturing runoff before it enters into any drainage system, sediment basins act as a kind of filter to reduce the amount of pollution that enters into local rivers, lakes, and other bodies of water. [caption id="attachment_197435" align="alignnone" width="617"]
Image Source: Tennessee Department of Environment & Conservation[/caption]
Sediment settles out of the water while it is held in the basin, reducing the negative impact on water quality that construction sites can typically cause. The image to the right displays an example of a typical Sediment Basin.
When are they Required?
In Texas, the Texas Commission on Environmental Quality (TCEQ) places all projects in one of two buckets - small and large construction sites. Small construction sites disturb between 1 to 5 acres of soil, while large construction sites disturb more than five acres. Anything less than one acre does not require the oversight of the TCEQ or any of their requirements, such as a temporary Sediment Basin.Elements of Design
The image below displays the standard layout of a Sediment Basin.
- Embankment height, side slopes, and top width
- Dimensions of the simmer, riser, weir, or other outlets
- Water surface elevation for the temporary control design storm (typically 2-yr, 24-hr) and the conveyance stormwater surface elevation (Varies depending upon the jurisdiction)
- Outfall pipe diameter, flow rate, and velocity
- Spillway cross section, slope, flow rate, and velocity
- Depth, width, length, and stone diameter for the riprap apron or an alternate dissipation structure, to be located at the outfall pipe and spillway discharge points