Village Response to Unusually High Accumulations of Seaweed

Case Studies: March and late April/May 2012

 
The Village's regular beach cleaning routine was disrupted when unusually large seaweed/seagrass accumulations were observed in March and May 2012.

From March 11-31, a relentless onshore wind (averaging 10 to 20 miles/hour) brought an unusual amount of Sargasso seaweed to the beach from its origin in the open ocean. The week of March 18-24 was the most challenging with abnormal high tides on Thursday, March 22, due to a new moon.  Universal Beach Services (UBS), the Village’s beach maintenance contractor, categorized this quantity as one of the highest ever seen along the Village shoreline.  During these very high tides, the contractor had almost no room to push the seaweed towards the dunes. The beach raking machine was dangerously operating in almost a foot of water.

An abnormal amount of seaweed and seagrass was deposited on the Village’s shoreline over three weeks from late April to mid-May 2012. This volume, estimated at approximately 18,500 cubic yards, was also one of the highest ever seen and comparable to the amount noted after Hurricane Andrew in 1992.

In response to the unusually high amounts of seaweed and seagrass on the beach, the Village Council approved a contingency program on May 8, 2012 to enhance seaweed/seagrass management operations. Additional equipment and manpower will be deployed over increased work hours to move the excess seaweed to the existing dune system. This program will provide access for marine turtles to the nesting beach/dune area that is being blocked by seaweed debris in the tidal zone, and prepare the beach for the renourishment project scheduled to begin in early June. It also should improve the beach going experience for residents and visitors.

Village Engineers and Biologists (Consultants) and Contractor met on May 11, 2012 with Florida Department of Environmental Protection (DEP) staff to observe the excessive seaweed debris pile-up on the beach. They reviewed potential seaweed disposal locations within the nearby dune system, and discussed potential procedural means to secure an emergency/expedited DEP authorization for the proposed operation.

As part of the contingency plan, the Contractor will clear the Village beach with different methods depending on the severity of seaweed/seagrass accumulation. The shoreline south of Grand Bay has received less seaweed, so the Contractor will continue to incorporate the material into the sand in front of the dunes per usual procedure.

The shoreline between the Grand Bay and the Commodore Club, at the northern boundary of the Village, has the most accumulation. The high volume does not allow incorporation of the material into the sand in front of the dunes. Instead, the material will be removed from the shoreline and staged north of the Island House, by the Commodore Club. This temporary storage site was identified for use by the Consultants and Contractor while the DEP permit is processed and finalized. The ultimate goal is to place the material on the dunes.

The Contractor will stage mounds of seaweed at specific places away from the lounge area and beach path. The operations will not block beach access and will be so conducted to minimize interference the daily beach routines of Island House and Commodore Club residents.

 

 


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