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This section provides guidance for using vegetated buffers in place of temporary sediment control devices used for storm water detention (see Section 10C-2). Vegetated buffers are areas of undisturbed vegetation, typically consisting of grasses. They can be very effective for removing sediment from storm water runoff. Typically, the use of vegetated buffers will be limited to projects involving small disturbed areas, such as 3R or emergency repair projects. When vegetated buffers are used, two rows of temporary sediment control devices are placed where storm water leaves the right-of-way. Storage volume calculations are not required. Contact the Agronomist or Earthwork Engineer when considering use of vegetated buffers in situations other than shown in this section.
| Clearly mark vegetated buffers in the R Sheets of the plans. Add a note in the plans that the contractor is not to disturb vegetated areas used as buffers. |
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Using a Vegetated Buffer for a Disturbed Area
When a vegetated buffer exists between a disturbed area and the outlet for the drainage area containing the disturbed area, it may be possible to use the buffer in place of the temporary sediment control devices discussed in Section 10C-2. When vegetated buffers are used as the only means of sediment removal, two rows of temporary sediment control devices, such as silt fence ditch checks or 20 inch perimeter and slope sediment control devices, should be placed in the ditch where the flow leaves the drainage basin, see Figure 1. These temporary sediment control devices provide an extra measure of sediment removal.
Figure 1: Flow through disturbed area and vegetated buffer.
Back to topUsing Design Details 570-11 and 570-12
For 3R projects that involve paved shoulders or pavement widening and culvert extensions, Design Details 570-11 and 570-12 should be used. These details include two rows of temporary sediment control devices and vegetated buffers, so storage volume calculations are not required.
Back to topFilling out Tabulation 100-34
For projects using vegetated buffers with temporary sediment controls, the basins filtered are still tabulated in Tabulation 100-34, see example below.
Include a Modified Standard Note 281-3 filled out similar to the example below indicating vegetated buffers and temporary sediment control devices are used in place of storm water detention.
