Charlie Hunsicker Manatee County Natural Resources Department & Thomas P. Pierro, P.E., D.CE Coastal Planning & Engineering, Inc. 1
Project Location Cortez Beach is located on the west coast of Florida in Manatee County near the southern end of the Anna Maria Island Gulf coastline. N 2
Project Area History To reduce the severity of erosion and stabilize the beach, three permeable piertype groins were installed in 1960 s and 1970 s. December 1973 (Source: FDOT). Designed by Sidney Makepeace Wood Damaged by the No-Name" storm of 1984 Repairs approved by FDEP (Dr. Dean) in 1986. Groin 3 under construction 3
December 1973 (Source: FDOT). an internationally known engineer credited with inventing the permeable piergroin to stop coastal beach erosion His most notable accomplishments in Florida were the groins constructed at the Colony Beach Club on Longboat Key, on the Manatee Groin 3 County under public construction beach and on Holmes Beach at Anna Maria Island. Source: St. Petersburg Times, November 2, 1968 4
Personal Account of Jim Kissik (2006) World War II Combat Veteran and decorated Navy Pilot Former City Councilman, City of Bradenton Beach Creation of three amazing erosion control groins along Cortez Beach The theory, which turned out to work very well, was to entrap moving sand just offshore as it tried to pass beneath the pier. One had only to fly down the beach and observe the effect. Each groin had its own arrow point of sand pointing out into the Gulf. Jim Kissick shows off a copy of his autobiography: "A Flyer's Dash" Source: The Islander tribute to veterans Nov 07 5
Over the Years The groins have been successful in stabilizing the beach, protecting Gulf Drive and have become a preferred surfing area on Anna Maria Island. They have also experienced deterioration and impacts of many tropical storms, leaving them dilapidated and unsafe. 6
Cortez Groins Feasibity Study (2012) Required by FDEP. Analyze the function and condition of the existing groins. Evaluate feasibility of reconstructing the Cortez groins from a coastal processes standpoint. Delft-3D numerical modeling of several alternatives. 7
Existing Groins at Cortez Beach Protect Gulf Drive hurricane evacuation route. Southerly sediment transport. Slow end losses from Central Beach Project. Existing groins are permeable. 8
Existing Conditions The groins are deteriorated and require replacement. 9
Tropical Storm Debby Originated in the southern Gulf of Mexico and strengthened into a Tropical Storm on June 23, 2012. Landfall 125 miles north of Cortez Beach. Source: http://weather.unisys.com (September 2012) 10
Storm Surge Slow movement and prolonged onshore flow generated a moderate storm surge for much of Florida s west coast. Source: http://tidesandcurrents.noaa.gov (September 2012) Storm surge and waves lasted for about 4 days in the vicinity of Cortez Beach. 11
Post-Storm Conditions July 2, 2012 12
Post-Storm Conditions Beach severely eroded. No dry beach at high tide. Photos taken by CPE July 2, 2012 13
Post-Storm Recovery Groins helped beach recover sand after the storm. Continued structural damage increases the need for repair. Photos taken by CPE January 25, 2012 14
Alternatives Analysis Six scenarios: 1. No action 2. Rebuild groins to existing permeabilities with uniform orientations 3. Remove all 3 groins 4. Replace with impermeable groins with uniform orientations 5. Rebuild all 3 groins with uniform permeabilities and orientations 6. Rebuild north and middle groins, remove south groin 15
Alternative 1 No Action Groins left in place Existing effective permeabilities: Northern groin 40%. Middle groin 25%. Southern groin 25%. 40% 25% 25% Basis for comparison to other alternatives
Alternative 2 Rebuild groins to existing permeabilities with uniform orientations Existing effective permeabilities: Northern groin 40%. Middle groin 25%. Southern groin 25%. 40% 25% 25% Southern groin realigned to match the two other structures
Alternative 3 Remove all three groins without replacement
Alternative 4 Impermeable groins Replace with sheet pile or sandtightened, rubble-mounds. Uniform orientations 0% 0% 0%
Alternative 5 Rebuild all three groins the same 40% permeability Uniform orientations 40% 40% 40%
Alternative 6 Rebuild North & Middle Groins, Remove South Groin North and middle rebuilt to effective permeabilities: Northern groin 40%. Middle groin 25%. Southern groin 25%. 40% 25% Remove south groin (pre-1973 condition)
Numerical Modeling Delft3D morphological model coupled with wave transformation model SWAN Regional wave grid from Panhandle to Keys Local grid resolution 5m x 5m with 8 vertical layers Calibration period: May 2006 to Oct 2009 Simulation period: 2011 + 5 yrs 22
Numerical Modeling 35 Wave Cases Wave Propagation Hs (ft) Current Map (ft/s) 23
Porous Plates Test Represent a permeable groin in the Deflt3D model. Simplified version created to test the relationship between loss coefficients (friction) and structure permeability. Effective permeability is determined from the ratio between the change in current speed crossing the porous plate. 24
Curve Fit for Cortez Groins Test results are site specific based on current velocities. 25
Alternative 2 - Results Uniform orientations Alternative 1 (No Action) is basis for comparison Straightening of the groin has negligible effect Mimics existing groin function
Alternative 3 - Results Removal of all three groins Erosion within and north of the groin field Erosion spikes at groins locations Temporary accretion south of groins
Alternative 4 - Results Impermeable groins Minor accretion updrift and within the groin field Erosion at Coquina Beach (South Groin to R-39).
Alternative 5 - Results Uniform permeabilities and orientations Refines performance of existing structures Maintains stability with a more uniform beach response
Alternative 6 - Results Remove southern groin Erosion within groin compartments Temporary accretion at Coquina Beach Large erosion spike at critical location
Findings The existing structures are functioning, but are dilapidated and require replacement. Replacement of groins is feasible and needed. Impermeable (solid) groins would not be the best solution. 40% permeability with matching orientation would improve performance and create a more uniform beach. Permeable Adjustable Groins (PAG) can be constructed to achieve the intent of the existing structures, and fine-tuned after installation based on their performance. 31
Permeable Adjustable Groin (PAG).. 32
Longboat Key PAG - Post TS Debby Islander Club Condominium July 2, 2012 33
Recommendations Reconstruct as Permeable Adjustable Groins based on Alternative 5 design. Perform annual monitoring annually and after major storm events to assess conditions and adjust permeability if needed. 40% 40% 40% 34
Status & Schedule Feasibility Study results presented to FDEP and received support for moving forward with the recommended plan. JCP Permit application being prepared. Field investigations being conducted: Hardbottom mapping Jet Probes (in water) Standard Penetration Tests (on beach) Final design will be based on results of field work. Construction scheduled for 2013-2014. 35
Special Thanks CPE Staff: Doug Mann, Chris Day, Michelle Rees FDEP staff who worked positively and proactively with Manatee County for their guidance and support on the timing, approach and need for this project. Danielle Fondren Bob Brantly Subarna Malakar Marty Seeling Lainie Edwards Alex Reed Vince George and others! 36
Thank You! 37