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North Keewaydin Island Erosion Control Project (2000-2013)


Humiston & Moore Engineers (H&M) was hired by the owner of the north end of Keewaydin Island to plan, design and implement an erosion control project to address the on-going erosion along the downdrift side of Gordon Pass. Keewaydin Island is located near the south end of the City of Naples, in Collier County, Florida.  The south jetty at Gordon Pass was constructed in 1960 when Gordon Pass became a Federal Navigation Project.  50 years of dredging the inlet modified the system and erosion stresses resulted in a chronic erosion problem on the north end of Keewaydin Island.  Sand maintenance dredged from Gordon Pass has historically been placed on the downdrift side of the inlet but only lasted approximately 2 years after placement. 


To address the problem H&M designed a program consisting of the following:

1) Sand tighten the south jetty at Gordon Pass. This was completed in 2003. 

2) Implement erosion control structures along north half of project and monitor.  Three T-groins were completed in 2003 and monitored until 2010.

3) Implement a later phase based on performance of (2) two breakwaters and detached groins, completed in Dec. 2012. 

4) Monitor while continuously assisting the USACE with their regulatory authorizations and easements for placement of beach sand from their maintenance dredging of Gordon Pass (Federal navigation project). 


As part of the design and planning, H&M completed a comprehensive study of Gordon Pass including extensive evaluation of past data, coastal process modeling including regional, inlet and beach morphology, and wave/structure interaction.  The result is now a system which is manageable such that future sand placement within the system on north Keewaydin Island will continue to transport to the south but in a more controlled manner, keeping pace with the management of the inlet. 


Sea turtle activity has improved and shorebird activity has remained without impact.  Success of the project can be attributed to maintaining open communications and information exchange with local environmental groups as well as the state and federal regulatory and resource agencies.



Project Tasks Included:


  • Hydrographic mapping

  • Inlet and Nearshore Morphology Modeling

  • Beach evolution modeling with proprietary N-line model 

  • Wave and sediment transport modeling

  • Analysis of erosion control alternatives

  • Hydrodynamic modeling 

  • Innovative T-groin design

  • Public awareness and coordination

  • Construction Observation



Scope Included:


  • Alternatives Analysis

  • Design and Permitting

  • Contract Documents & Specifications

  • Construction Observation

  • Project Monitoring



H&M Staff that worked on this project:


  • Brett D. Moore, P.E., Project Manager/Project Engineer

  • Mohamed Dabees, Ph.D., P.E., Regional & local coastal process modeling, nearshore and inlet morphology modeling.

  • Marc Damon, Coastal Engineer, modeling and technical support

  • Steve Foge, Monitoring & Analysis

  • Michael Mann, AutoCAD and permitting support



Project Contact Information

Mr. Jim Murphy

Continental Construction

Office: (239) 434-8437

Cell: (239) 253-7179


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