Page Content

Nourishing Beaches


Decrease text sizeRestore default text sizeIncrease text size  Print this page

Beach nourishment is a unique activity that revitalizes the beach/dune system by adding sand to an eroding beach. Nourishment is done by locating a source of beach-quality sand and transporting it to the beach by truck or pipeline. It is then placed on the beach in a very specific manner to maximize the longevity of the nourishment.
How long will it take for sand to be placed on the beach?
The pumping operation can take several months. The exact duration will depend on the size of the project, the schedule of the contractor, and the weather. It is to the benefit of the contractor to finish as quickly as possible.
Will the beach be accessible during construction?
Pipe may be laid along the beach to be nourished. Gently sloping walkways will be placed over the pipe to allow access to the beach. Access to the area near the pipe discharge will be restricted due to movement of equipment and discharge of the sand slurry. The pipe length will be changed as the operation proceeds down the beach. As the discharge moves, the area of restricted access will also move. In this area, the contractor will relocate material and smooth the beach with heavy machinery and conduct surveys to assure that construction conforms with plans. Soon after placement, typically a matter of days, it will be possible to walk on the new beach. So, as the discharge pipe is moved down the beach, a wider beach area will become available to the public.
Is the beach safe during/after a nourishment project?
The beach nourishment will be extended seaward at about the elevation of the existing beach, but sometimes the seaward slope may be steeper than the natural slope. It is possible that a steep slope, in a small area, will form at the water's edge along the new sediment/sand. The slope may form with a 1- to 3-foot drop and pose a possible danger to those who might unexpectedly encounter the drop. The slope will disappear as the changing water level and waves smooth the profile. This type of slope typically appears on sandy beaches during storms.
Why does it seem like the newly created beach immediately begins to shrink?
Sand is mainly pumped to the dry portion of the beach to form the construction profile. Over the first few months following beach nourishment, the wide beach created will quickly decrease in width to approach the design profile. During this rapid period of adjustment, the sand is taken from the upper beach by the waves and currents, and is distributed throughout the beach profile, typically out to the nearshore sand bars. This adjustment is normal, and is not a cause for alarm. This movement of sand contributes to the development of an overall healthy beach and is taken into account in the design template for the beach profile.

 

In the long term, over years, the beach nourishment will provide sand to the neighboring beaches. This is called a "down-drift" benefit of the nourishment, meaning that adjacent beaches will receive sand redistributed from the nourishment area by the longshore current. Beaches are dynamic and evolve over time. In the winter, sand is removed from the beach and deposited on the nearshore bars. The gentle waves of summer then move the sand from the bars back to the beach face. Beach nourishment will not stop shoreline recession in eroding areas, but only delay the shoreline from retreating. Beach nourishment increases the life span of the shore. For this reason, future periodic beach re-nourishment projects will be necessary.
Why does the new sand look and smell different from the sand that was already on the beach?
The new sand may be darker than the existing sand on the beach because it contains some fine silts and clays, as well as organic matter. There may also be a "rotten egg" odor associated with the organic material in the dredged material as it is exposed to oxygen. Waves, tidal influences, and rain will flush this fine material offshore where it will continue to move to very deep water. Such a process also occurs naturally when rivers discharge sediments; the sand stays on the beach while the fine material moves offshore. The sun will also quickly bleach the exposed sand.