CHAPTER 8 



ENGINEERING ANALYSIS: CASE STUDY 



Page 

 I INTRODUCTION 8-1 



II STATEMENT OF PROBLEM 8-1 



III PHYSICAL ENVIRONMENT 8-1 



1 . Site Description 8-1 



2. Water Levels and Currents — Storm Surge and Astronomical Tides.. 8-7 



a. Design Hurricanes 8-7 



b. Estimate of Storm Surge 8-9 



c. Observed Water Level Data, Breakwater Harbor, Lewes, 



Delaware 8-10 



d. Predicted Astonomical Tides 8-12 



e. Design Water Level Summary 8-12 



3. Wave Conditions 8-12 



a. Wave Conditions on Bay Side of Island 8-12 



b. Wave Conditions on Ocean Side of Island 8-26 



IV PRELIMINARY DESIGN 8-46 



1. Selection of Design Waves and Water Levels 8-46 



a. Water Levels 8-46 



b. Wave Conditions on Bay Side of Island 8-47 



c. Wave Conditions on Ocean Side of Island 8-47 



2. Revetment Design: Ocean Side of Island 8-47 



a. Type of Wave Action 8-47 



b. Selection Between Alternative Designs 8-47 



3. Diffraction Analysis: Diffraction Around Breakwater 8-74 



4. Preliminary Design of Quay Wall Caisson 8-75 



a. Nonbreaking Wave Forces on Caisson 8-76 



b. Stability Computations 8-81 



c. Caisson Stability After Backfilling 8-84 



d. Soil Bearing Pressure 8-85 



e . Summary 8-85 



V COMPUTATION OF POTENTIAL LONGSHORE TRANSPORT 8-85 



1 . Deepwater Wave Angle (a ) 8-85 



2. Calculation of Average F (a ) 8-87 



3. Potential Longshore Transport Computed by Energy Flux Method.. 8-89 



