Architect-Engineering Services for Environmental Engineering Services at Various Navy and Marine Corps Activities, Pacific Basin and Indian Ocean Areas Contract No. N62742-05-D-1873 Amendment 11 Task Order No. 0009 Ocean Current Study Ocean Dredged Material Disposal Site Apra Harbor, Guam Final Report Prepared For: Department of the Navy Naval Facilities Engineering Command Pacific 258 Makalapa Drive, Suite 100 Pearl Harbor, Hawaii 96860-3134 August 2007 Ocean Current Study Ocean Dredged Material Disposal Site Apra Harbor, Guam Final Report Prepared For: Department of the Navy Naval Facilities Engineering Command Pacific 258 Makalapa Drive, Suite 100 Pearl Harbor, Hawaii 96860-3134 Prepared By: Weston Solutions, Inc. 2433 Impala Drive Carlsbad, California 92008 Under Contract To: Belt Collins Hawaii Ltd. 2153 North King Street, Suite 200 Honolulu, Hawaii 96819 August 2007 Final Report Ocean Current Study Ocean Dredged Material Disposal Site, Apra Harbor, Guam August 2007 TABLE OF CONTENTS 1.0 INTRODUCTION .............................................................................................................. 1 1.1 Background............................................................................................................. 1 1.2 Purpose and Need ................................................................................................... 1 1.3 Study Area .............................................................................................................. 2 2.0 NAVY COASTAL OCEAN MODEL (NCOM)................................................................ 6 3.0 DATA POST-PROCESSING............................................................................................. 7 4.0 PHYSICAL OCEANOGRAPHY - CURRENTS............................................................... 8 4.1 Regional Patterns .................................................................................................... 8 4.1.1 Surface Currents.......................................................................................... 8 4.1.2 Intermediate Layer Currents ..................................................................... 15 4.1.3 Bottom Currents........................................................................................ 36 4.2 ODMDS Alternative Site-Specific Patterns.......................................................... 36 4.2.1 Surface Currents........................................................................................ 36 4.2.2 Intermediate Layer Currents ..................................................................... 45 4.2.3 Bottom Currents........................................................................................ 45 4.3 Suitability of Modeled Current Data..................................................................... 50 5.0 MODELED DISPOSAL EVENTS .................................................................................. 51 5.1 STFATE Model .................................................................................................... 51 5.1.1 Model Use................................................................................................. 52 5.1.2 Results....................................................................................................... 56 5.2 Hamilton Model.................................................................................................... 64 6.0 CONCLUSIONS............................................................................................................... 64 7.0 REFERENCES ................................................................................................................. 66 APPENDIX A Vector Plots of Daily Averaged Current Velocities by Month for Each Location by Depth Weston Solutions, Inc. i Final Report Ocean Current Study Ocean Dredged Material Disposal Site, Apra Harbor, Guam August 2007 LIST OF TABLES Table 1. Depth Intervals of NCOM Derived Current Data............................................................ 7 Table 2. Physical Characteristics of Coarse and Fine-Grained Dredged Material Suitable for Disposal at a Potential ODMDS ................................................................................................... 53 Table 3. Current Vectors Used for Dry and Wet Season Scenarios in STFATE Model Runs.... 55 Table 4. Modeled Thickness and Area of Deposits for Disposal of 300,000 cy or 1 mcy of Fine or Coarse-Grained Dredged Material............................................................................................ 58 LIST OF FIGURES Figure 1. Combined ZSF Eliminated Areas................................................................................... 3 Figure 2. Zone of Siting Feasibility ............................................................................................... 4 Figure 3. Regional Study Area and Bathymetry............................................................................ 5 Figure 4. Vector Plots of Daily Averaged Current Velocities by Month for Each Location at 33 ft (10 m) Depth.............................................................................................................................. 10 Figure 5. Interpolation of Mean Current Directions at 10 Meters Depth for the Dry Season ..... 11 Figure 6. Interpolation of Mean Current Speeds at 10 Meters Depth for the Dry Season........... 12 Figure 7. Interpolation of Mean Current Directions at 10 Meters Depth for the Wet Season..... 13 Figure 8. Interpolation of Mean Current Speeds at 10 Meters Depth for the Wet Season .......... 14 Figure 9. Vector Plots of Current Velocity by Depth for the Southeast Regional Boundary...... 16 Figure 10. Vector Plots of Current Velocity by Depth for the Northeast Regional Boundary.... 17 Figure 11. Vector Plots of Current Velocity by Depth for the Southwest Regional Boundary... 18 Figure 12. Vector Plots of Current Velocity by Depth for the Northwest Regional Boundary... 19 Figure 13. Vector Plots of Current Velocity by Depth for a Location Near the Northwest ODMDS Alternative Area. ........................................................................................................... 20 Figure 14. Rose Diagram of Current Velocities by Depth for the Southeast Regional Boundary ....................................................................................................................................................... 21 Figure 15. Rose Diagram of Current Velocities by Depth for the Northeast Regional Boundary ....................................................................................................................................................... 22 Figure 16. Rose Diagram of Current Velocities by Depth for the Southwest Regional Boundary ....................................................................................................................................................... 23 Figure 17. Rose Diagram of Current Velocities by Depth for the Northwest Regional Boundary ....................................................................................................................................................... 24 Figure 18. Rose Diagram of Current Velocities by Depth for a Location Near the Northwest ODMDS Alternative Area ............................................................................................................ 25 Figure 19. Vector Plots of Daily Averaged Current Velocities by Month for Each Location at 1,300 ft (400 m) Depth.................................................................................................................. 26 Figure 20. Vector Plots of Daily Averaged Current Velocities by Month for Each Location at 4,900 ft (1,500 m) Depth............................................................................................................... 27 Figure 21. Interpolation of Mean Current Directions at 400 Meters Depth for the Dry Season . 28 Figure 22. Interpolation of Mean Current Speeds at 400 Meters Depth for the Dry Season....... 29 Figure 23. Interpolation of Mean Current Directions at 400 Meters Depth for the Wet Season. 30 Figure 24. Interpolation of Mean Current Speeds at 400 Meters Depth for the Wet Season ...... 31 Weston Solutions, Inc. ii Final Report Ocean Current Study Ocean Dredged Material Disposal Site, Apra Harbor, Guam August 2007 Figure 25. Interpolation of Mean Current Directions at 1500 Meters Depth for the Dry Season 32 Figure 26. Interpolation of Mean Current Speeds at 1500 Meters Depth for the Dry Season..... 33 Figure 27. Interpolation of Mean Current Directions at 1500 Meters Depth for the Wet Season34 Figure 28. Interpolation of Mean Current Speeds at 1500 Meters Depth for the Wet Season .... 35 Figure 29. Vector Plots of Daily Averaged Current Velocities by Month for Each Location at 8,200 ft (2,500 m) Depth............................................................................................................... 37 Figure 30. Interpolation of Mean Current Directions at 2500 Meters Depth for the Dry Season 38 Figure 31. Interpolation of Mean Current Speeds at 2500 Meters Depth for the Dry Season..... 39 Figure 32. Interpolation of Mean Current Directions at 2500 Meters Depth for the Wet Season40 Figure 33. Interpolation of Mean Current Speeds at 2500 Meters Depth for the Wet Season .... 41 Figure 34. Vector Plots of Seasonal Average Currents by Depth for Specific Areas within the Regional Study Area....................................................................................................................