Beach plan shifts away from Beer Can island

STEVE REID
Editor & Publisher
sreid@lbknews.com

Longboat Key Town Manager Dave Bullock gave a north-end beach update in which he concluded by saying he wants to spend the summer talking with the town’s beach engineer, Coastal Planning & Engineering, about the effectiveness of placing two semi-permeable groins to help stop erosion that can threaten the 360 north and Whitney Beach condominiums.

Bullock’s decision to try and move forward with two semi-permeable groins contradicts the engineer’s earlier recommendation in February that stated a large terminal groin farther north on the Northwest tip of the island along with the two semi-permeable groins is the best way to preserve and protect Beer Can Island, the popular undeveloped recreation area known for boating, birding and strolling.

Bullock said he sees the Town’s beach plan resting on four primary objectives:

• To protect coastal properties through our beaches.

• To maintain resident and visitor access.

• Minimize adverse impact on coastal resources.

• To construct the smallest feasible footprint in our attempt to address erosion.

 

History of Beer Can Island

At the June 21 workshop Bullock took the Commission and audience on a historical tour showing how the north end — particularly Beer Can Island (AKA Greer Island) — has morphed in fits of sand erosion and accretion. He looked back over 70 years with a final flourish of rapid succession images showing Beer Can Island changing from a separated sliver of sand to the large, jutting configuration of today.

And Bullock then said he wants to take time to talk to the town beach consultants of more than a decade, Coastal Planning & Engineering, about using two permeable beach groins about 300 feet long placed slightly north of the aforementioned condominiums.

“Sand will wash away from Beer Can Island but the beach we care about most will remain,” said Bullock.

He said the Town had seen three structures presented in the past, but he wants to see if two would meet the Town’s objectives.

Commissioner Pat Zunz disagreed, saying we should look at the long terminal groin as well with her concern being if the Town does only semi-permeables, “We will have to do a terminal groin in six years anyway.”

Zunz also said that she is concerned that none of the scenarios take into account any major storms and after-effects.

Commissioner Jack Duncan asked if it was possible to phase the groins and then evaluate as we go. Mayor Jim Brown said he thought Bullock’s approach is conservative and that he will know more after talking with the DEP (Department of Environmental Protection) and the engineers.

Consensus was reached that the Town Manager should move forward with his two-groin idea and for him to evaluate with the engineers and the DEP over the summer.

 

On background

In a February 2012 report by CP&E, the firm told the Commission that if the groins are not placed north of the 360-North Condominium and a terminal groin is not used, the erosion at Beer Can Island would be so severe that the small island could eventually be lost. For this reason CP&E did not recommend moving the groin south toward 360 north as requested by the Town Commission last November.

Manatee County Commissioner Joe McClash agrees:

“I cannot support the recommendations of destroying the recreational area, Beer Can Island, that many people now enjoy. It would take away the natural beauty myself and others have pledged to protect.”

The original request by town commissioners to have no groins placed on Greer Island was to avoid involving Manatee County, which owns Greer Island, in case it did not grant permission for the construction. But placing a groin on Beer Can island should be a very small hurdle the Town Manager said on June 21 since the deed to the property states that no structure can be placed on the land except to protect the property. That, by definition, is what a groin does.

CPE’s official recommendation is to leave the first of the groins on Greer Island.

“The Recommended Inlet Management Plan for Longboat Pass includes a new terminal groin on the north end of Longboat Key, which would be constructed on property owned by Manatee County.

If the terminal groin were moved to the 360 North Condominium property, the area between the structure and Longboat Pass would be subject to higher erosion rates and increased shoreline retreat that would occur as the inlet channel moved closer to Longboat Key. The channel migration pattern could potentially increase the maintenance-dredging requirement in the Authorized Channel of Longboat Pass.

“Moving the location of the terminal groin south to the 360 North property would result in increased erosion of Greer Island and would not meet one of the goals of the Inlet Management Study, which was to preserve Greer Island. It is likely that FDEP would not be as favorable to the southerly-located groin. For these reasons we do not recommend pursuing this alternative,” according to the CPE report.

 

The erosion

Longboat Pass is an inlet that separates Anna Maria Island from Longboat Key and connects Sarasota Bay and the Gulf of Mexico. According to the CPE report, both Anna Maria Island and Longboat Key have shorelines that are classified by the FDEP as critically eroded.

The area from Greer Island to Palmetto Avenue on Longboat Key has experienced some of the highest erosion rates on Longboat Key, losing 35 to 131 cubic yards/foot between July 2006 and October 2010, according to CPE.

 

Moving the proposed groins

During the Nov. 3, 2011 workshop, the Longboat Key Town Commission asked CPE how the terminal groins could be constructed if Manatee County were unwilling to allow the structure on Greer Island.

As a result of this question, CPE ran a new model if the proposed terminal groin on the north end of Longboat Key would be moved south, onto the 360 North condominium property within the town’s jurisdictional limits.

This scenario, termed by CPE as the “Modified Terminal Groin Scenario,” was assessed to determine the changes to the beach profile as a result of relocating the proposed terminal groin.

 

Modeling results from moving the groin

According to the CPE report, the Modified Terminal Groin Scenario indicates that between 360 North Condominium and Beachwalk Condominium, more of the dredge spoil from Longboat Pass will remain on the beach than under the original Recommended Inlet Management Plan.

However, beachfront erosion rates between the terminal groin and Longboat Pass would be higher than either the No Action Scenario or the Recommended Inlet Management Plan.

The potential for higher erosion rates on Beer Can Island, north of the relocated groin, is doing part to blockage of northerly-directed sediment movement at the groin.

According to CPE, this results in increased scouring along the northern end of Greer Island, bringing the inlet channel closer to the north end of Longboat Key. Since the channel moves south, the existing channel will fill in, which means that maintenance dredging of Longboat Pass will increase with the Modified Terminal Groin Scenario from the Recommended Inlet Management Plan.