Typical diversion methods for working in the dry and their applicability.
Link to this table
| Stream crossing type |
Applicability |
Limitations |
| Temporary bridge |
- Results in least disturbance to stream bed and banks compared to other stream crossing methods
- Typically no time of year restrictions for use
- Generally most appropriate for streams with high flow velocities or steep gradients
|
Use in large channels may require pier(s) or other supports, which increase disturbance to stream (see Construction recommendations and specifications). |
| Temporary culvert (pipe) |
- Most common temporary stream crossing
- Most appropriate for short-term use
- Generally appropriate for perennial or intermittent streams
- Generally preferred over fords as disturbance to stream is limited to construction and removal
|
- May not be appropriate for large streams or during high flow conditions
- Causes greatest obstruction to flow
- May damage channel cross-section; culvert crossings should be planned to limit the number of crossings needed
- Not appropriate for streams that are vertically degraded or incised
|
| Temporary ford (drive-through) |
- Most appropriate for short-term use.
- Generally appropriate for ephemeral or low flow perennial streams.
- Used when bridge or culvert crossings are not feasible; typically very shallow streams where stream banks are less than 4 feet above the stream invert.
|
- Use should be limited to dry season.
- Use should be limited to streams whose beds are armored.
- May degrade water quality due to contact with construction vehicles and equipment
|
