Office of Coastal Management
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Sandusky, OH 44870
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Coastal Structures

Sand Bypassing

Sand bypassing involves the intentional relocation of sand from an updrift area of accretion to areas downdrift. Typically, this is performed at navigation channels and harbors where jetties and breakwaters capture a significant amount of sand. Prior to determining if bypassing is applicable at a project site, the material to be bypassed should be sampled and tests such as grain size analysis, organic content and toxin levels should be performed to ensure that the material meets environmental quality standards for Lake Erie.

Bypassing of sand can occur through either hydraulic dredging where a pump pipes the sand across the inlet, or through mechanical dredging which requires a dredge and barge or truck to move the sand. A pump is often more useful in areas where continuous or yearly sand bypassing will occur because once the system is installed it can be used whenever necessary. Mechanical dredging is more useful in those instances where a longer time period will occur between bypassing operations.

An additional factor to consider when determining the most effective type of bypassing is the type of the material being bypassed. For instance in areas where debris accumulates, pumping may not be feasible as the debris may clog the system. In the case of dredging, if the material is to be relocated by truck, appropriate access is necessary at both the point of dredging and at the point of relocation.

The location at which the material is bypassed should be carefully considered with respect to water depth and presence of shore structures, and the predominant direction of littoral drift. A series of site surveys are often required to determine the location and quantity of material that needs to be dredged and to determine the best location to place the relocated sand. Care should be taken to avoid placing material in depths of water that are too great to allow the sand to return to the shore area. Also avoid placing sand directly adjacent to other structures that would impede the normal downdrift movement of the sand.

Perhaps the greatest challenge with conducting sand bypassing is the cost. Initial costs for the pump system will be quite high with the routine costs of pumping being much lower. Mechanical dredging operations will be costly each time the dredging occurs, but this option may be utilized on a less frequent basis when compared to the pump system.

To maintain a sand bypassing system that depends on pumps, the pipes will need to be monitored for any clogs or debris obstructions. Maintenance of mechanical components of the system,will also be necessary. If a mechanical dredge is used for sand bypassing, there is no required maintenance of the system as the dredge will be removed during periods of inactivity.

Sand bypassing is an intensive process that will require the work of a contractor and other trained professionals (i.e. dredge operator).

Essential Information

Function: Intentional relocation of sand from an updrift area of accretion to areas downdrift.

Appearance: Sand moving from one location to another.

Materials: Hydraulic dredge or mechanical dredge.

Issues: Debris clogging the hydraulic dredge equipment; and for mechanical dredging, appropriate access is necessary at both the point of dredging and at the point of relocation.