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Central Basin Coastal Engineering Analysis, December 2015

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Central Basin Coastal Engineering Analysis, December 2015 Technical Report COASTAL ENGINEERING ANALYSIS, REMEDIATION CONCEPT DESIGN AND IMPACT ANALYSIS PORT OF SAN FRANCISCO CENTRAL BASIN, CALIFORNIA Technical Report COASTAL ENGINEERING ANALYSIS, REMEDIATION CONCEPT DESIGN AND IMPACT ANALYSIS PORT OF SAN FRANCISCO CENTRAL BASIN, CALIFORNIA This Technical Report presents the results of coastal engineering analysis and concept design performed by Coast & Harbor Engineering to develop coastal engineering design criteria and remediation (capping) design concepts, and impact analysis conducted for various proposed activities within Central Basin for the Port of San Francisco, CA. Prepared by Scott W. Fenical, PE 155 Montgomery Street, Suite 301 San Francisco, CA 94104 Phone: 415.773.2164 Fax: 415.773.2396 TABLE OF CONTENTS Executive Summary .........................................................................................................................1 1. Introduction ..........................................................................................................................2 2. Coastal Conditions Analysis ................................................................................................2 2.1. Vertical Datums .......................................................................................................3 2.2. Wind Analysis ..........................................................................................................4 2.3. Wind-Waves ............................................................................................................5 2.4. Tidal Currents and Sedimentation ...........................................................................7 2.4.1. Tidal Current Model Setup and Validation ..................................................7 2.4.2. Measured Sedimentation Analysis .............................................................10 2.4.1. Sedimentation Model Calibration ..............................................................11 3. Sediment Remediation Concept Design ............................................................................12 3.1. Design Criteria .......................................................................................................13 3.2. Remediation Concept Design ................................................................................15 4. Impact Analyses .................................................................................................................17 4.1. Effects of Wharf 8 Removal on Waves in Central Basin ......................................17 4.2. Effects of Wharf 8 Removal on Sedimentation in Central Basin ..........................18 4.3. Effects of Crane Cove Park Beach Construction on Sedimentation in Central Basin ......................................................................................................................19 4.4. Effects of Deepening Dredge Units 1-3 on Sedimentation in Central Basin .........20 5. Conclusions ........................................................................................................................21 6. References ..........................................................................................................................22 Appendix A – Remediation Concept Design Drawings Appendix B – Remediation Construction Cost Estimate by M. Lee Corporation FIGURES Figure 1. San Francisco Central Basin location ...............................................................................2 Figure 2. Wind speed and direction distribution (wind rose) at Alameda NAS wind station .........4 Figure 3. Extreme sustained wind speed and direction for return periods between 2 and 100 years5 Figure 4. Wind-wave modeling domain for San Francisco Bay (left) and nearshore domain at project site (right) .................................................................................................................5 Figure 5. 100-year significant wave heights on Bay........................................................................6 Figure 6. 100-year significant wave heights in project area ............................................................7 Figure 7. Tidal current modeling domain (Pacific Ocean extents not fully shown) ........................8 Figure 8. Typical current speeds and directions during peak ebb (top) and flood (bottom) currents around Central Basin. A color contour legend is presented at top left of each snapshot. ...9 Figure 9. Validation of tidal current model with predicted tides at Alameda (top) and observed current near Wharf 8 (bottom) ...........................................................................................10 Figure 10. Hydrographic survey data used in measured sedimentation analysis, 1999 (top) and 2013 (bottom).....................................................................................................................11 Figure 11. Measured sedimentation rates in Central Basin ...........................................................11 Figure 12. Model predicted sedimentation rates in Central Basin, with measured rates noted in white boxes ........................................................................................................................12 Figure 13. Proposed remediation area boundary (hatched area)....................................................13 Figure 14. Storm wave heights (significant wave heights) chosen for remediation area design (does not include effects of proposed sheetpile wall) ........................................................14 Figure 15. Bottom velocities generated by the tug Delta Billie after reaching approximately steady flow conditions .......................................................................................................14 Figure 16. Required armor stone diameter for stability under propeller wash forces ...................16 Figure 17. View from north end of Wharf 8 looking south (left) and timber screen on Wharf 8 (right), looking west ...........................................................................................................17 Figure 18. FLOW-3D storm wave transmission under/through Wharf 8 ......................................18 Figure 19. Sedimentation rates with Wharf 8 in place (left) and rates/changes in rates following Wharf 8 removal (right) .....................................................................................................19 Figure 20. Modeling domain bathymetry for existing conditions (left) and with installation of Crane Cove Park Beach (right) ..........................................................................................20 Figure 21. Sedimentation rates before (left) and after (right) installation of Crane Cove Park Beach..................................................................................................................................20 Figure 22. Existing elevations around Dredge Units 1-3, and proposed deepening (right) ...........21 Figure 23. Sedimentation rates before (left) and after (right) deepening of Dredge Units 1-3 .....21 TABLES Table 1. Datum Elevations at Pier 22.5 (Epoch 1983-2001) ...........................................................3 Table 2. Differences in Elevations between Golden Gate and Pier 22.5 (Epoch 1983-2001) .........3 Table 3. Tug Particulars for Propeller Wash Modeling .................................................................14 Technical Report Coastal Engineering Analysis, Remediation Concept Design, and Impact Analysis, Port of San Francisco Central Basin, CA Executive Summary Coast & Harbor Engineering.(CHE) was contracted by the Port of San Francisco (POSF) to develop coastal engineering design criteria and remediation (capping) design concepts, as well as impact analysis for various proposed activities within the Central Basin. Impact analysis included the potential removal of Wharf-8 and its effect on tidal circulation and wave climate in the Central Basin, as well as impacts of installing the Crane Cove Park Beach, and deepening Dredge Units 1-3 in Central Basin to depth 35 feet (MLLW). Coastal engineering design criteria were developed to support the Crane Cove Park Beach design effort by others, including extreme storm conditions, tidal current and sedimentation conditions, and propeller wash conditions generated by nearby tug activities. A concept design was generated for remediation of contaminated sediment at the southwest corner of Central Basin. The concept design consisted of limited excavation, installation of a rock cap, and protective breakwater structure to protect the area from excessive tug-induced propeller wash. Analysis results in recommendations for remediation cap location, total thickness, and armor stone size. Impact analyses performed in Central Basin indicated the following: • Removal of Wharf 8 is not likely to significantly affect the wave climate or extreme wave heights within Central Basin • Removal of Wharf 8 can be expected to slightly increase the overall sedimentation in Central Basin and shift the general sedimentation patterns • Crane Cove Park Beach construction is not likely to significantly affect the tidal currents or sedimentation within Central Basin • Deepening of Dredge Units 1-3 to 35 feet (MLLW) +2 feet over-dredging can be expected to increase the overall sedimentation in Central Basin and shift the general sedimentation patterns Technical Report November 4, 2014 Coastal Engineering Analysis, Remediation Concept Design, and Impact Analysis Page 1 Port of San Francisco Central Basin,
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