Lee County selected H&M to assist with local implementation of a Federal Erosion Control Project.  The project area included approximately three miles of eroded shoreline north of Boca Grande Pass.  The erosion was most severe in front of a seawall just north of the inlet.

 

H&M completed a detailed analysis of the history and causes of erosion by employing the NLINE model to simulate existing conditions and evaluate design alternatives.  The model provided time–dependent simulation of wave transformation, sediment transport, and 3D beach changes for various temporal and spatial scales.  The N-line model offers practical run-times for this type of complex simulation and provided efficient model calibration and verification rendering a high level of confidence in the model predictive capability.

 

The design included approximately 1,000,000 cubic yards of beach fill along 3 miles of shoreline, and erosion control structures near the south end stabilize the fill, improve sand benefits to the park and extend project life.  The beach fill was completed in 2007 at a cost of $11.2 million. The structures are being re-evaluated based on the changed conditions and have not yet been constructed due to funding limitations. 

 

Project Tasks:

• Hydrographic mapping

• Borrow area investigation

• Beach evolution modeling with proprietary N-line model 

• Downdrift impact evaluation

• Analysis of erosion control alternatives

• Hydrodynamic modeling 

• Innovative breakwater & T-groin design

• Public awareness and coordination

• State and federal funding

• Beach nourishment

 

Scope:

• Design and Permitting

• Contract Documents & Specifications

• Construction Observation

• Project Monitoring

• Hardbottom mitigation