Typical diversion methods for working in the dry and their applicability

Typical diversion methods for working in the dry and their applicability.
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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.	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
Diversion channels/ditches	Most appropriate for short duration projects with low <span title="Baseflow (also called drought flow, groundwater recession flow, low flow, low-water flow, low-water discharge and sustained or fair-weather runoff) is the portion of streamflow delayed shallow subsurface flow". baseflows. Requires sufficient area in the stream corridor to construct the diversion channel. Requires a positive slope to allow flow through the channel.	Not easily moved or adjusted after installation. Insufficient flow capacity in pipe can cause diversion failure and severe erosion.
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.	Construction equipment cannot be driven over pipes. Insufficient flow capacity in pipe can cause diversion failure and severe erosion.
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.	Limited by pump capacity, and continuous pumping can be costly. Pump failure can result in delays and additional costs.