Typical diversion methods for working in the dry and their applicability.
Link to this table
Diversion practice |
Applicability |
Limitations |
Partial stream diversion |
- Suitable when work area is on one side of the stream channel or stream bank.
- Appropriate stream size and duration of use depends on materials.
- Structures are placed in the stream to confine flow to one side while work progresses on the “dry” side.
- Sand bags, stone, or similar diversions are appropriate for smaller streams and work areas, while coffer dams, portable dams, or other similar barriers are necessary for larger water bodies.
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- Not easily moved or adjusted after installation.
- Sand bag or stone in-channel diversions are typically not appropriate for larger streams.
- May be subject to failure or erosion during storm events.
- Results in a smaller area of stream access compared to other diversion methods.
- See Diversion barrier controls (cofferdams/ temporary dikes) for more information
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Diversion channels/ditches |
- Most appropriate for short duration projects with low baseflows.
- Requires sufficient area in the stream corridor to construct the diversion channel.
- Requires a positive slope to allow flow through the channel.
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- Not easily moved or adjusted after installation.
- Insufficient flow capacity in pipe can cause diversion failure and severe erosion.
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Piped diversions/ culverts (bypass pipe) |
- Most appropriate for short duration projects with low baseflows.
- Appropriate when the required flow diversion can be accomplished without pumping.
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- Construction equipment cannot be driven over pipes.
- Insufficient flow capacity in pipe can cause diversion failure and severe erosion.
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Pumped diversions (“pump-arounds”) |
- Most appropriate for short duration projects with low baseflows.
- Typically used when there is limited space for a diversion.
- Pump(s) must be sized to accommodate stream baseflow.
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- Limited by pump capacity, and continuous pumping can be costly.
- Pump failure can result in delays and additional costs.
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