technical report coastal engineering analysis, remediation ... · technical report coastal...

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 November 4, 2014 Coastal Engineering Analysis, Remediation Concept Design, and Impact Analysis Page 1 Port of San Francisco Central Basin, California

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 Coastal Engineering Analysis, Remediation Concept Design, and Impact Analysis, Port of San Francisco Central Basin, CA

1. Introduction

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 (Figure 1, left). Impact analysis included the potential removal of Wharf-8, shown in Figure 1 (right) 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).

Figure 1. San Francisco Central Basin location

2. Coastal Conditions Analysis

CHE evaluated coastal hydrodynamic conditions in Central Basin, including storm waves, propeller wash and tidal currents/sedimentation. Numerical modeling tools were developed to predict storm wind-waves on a Bay-wide scale, CFD modeling was performed to estimate potential tug-induced bottom velocities from propeller wash, and tidal current/sedimentation modeling on a Bay-wide scale was performed to determine existing and future sedimentation rates under a variety of proposed modifications within the area.


2.1. Vertical Datums

Tides in San Francisco Bay are semi-diurnal (two low tides and two high tides each day). Predicted tide data from the National Oceanic and Atmospheric Administration

(NOAA) Pier 22.5 Station (Latitude 37° 47.4’N, Longitude 122° 23.2’W) were used to develop tidal elevation statistics. Table 1 shows the fixed and tidal datum information available for the Pier 22.5 location which was used to approximate tidal fluctuations at the Central Basin site. Table 2 shows tidal elevation differences between the Presidio station at the Golden Gate and the Pier 22.5 station.

Table 1. Datum Elevations at Pier 22.5 (Epoch 1983-2001)

Datum Elevation

[feet, MLLW] Elevation

[feet, CITY DATUM]

Highest Observed Water Level (1/27/1983) n/a n/a

Highest Astronomical Tide (12/31/1990) 7.65 -3.61

Mean Higher-High Water 6.26 -5.00

Mean High Water 5.64 -5.62

Mean Tide Level 3.38 -7.88

Mean Sea Level 3.27 -7.99

Mean Diurnal Tide Level 3.13 -8.13

Mean Low Water 1.12 -10.14

Mean Lower-Low Water 0.00 -11.26

Lowest Astronomical Tide (5/25/1986) -2.06 -13.32

Lowest Observed Water Level (12/17/1933) n/a n/a

Table 2. Differences in Elevations between Golden Gate and Pier 22.5 (Epoch 1983-2001)

Datum Description Difference

[feet]

EHW Highest Observed Water Level (1/27/1983) N/A

HAT Highest Astronomical Tide (12/31/1990) 0.38

MHHW Mean Higher-High Water 0.42

MHW Mean High Water 0.41

MTL Mean Tide Level 0.20

MSL Mean Sea Level 0.15

DTL Mean Diurnal Tide Level 0.21

MLW Mean Low Water -0.01

MLLW Mean Lower-Low Water 0.00

LAT Lowest Astronomical Tide (5/25/1986) 0.03

ELW Lowest Observed Water Level (12/17/1933) N/A


2.2. Wind Analysis

San Francisco Bay has an energetic wind climate, with winds at Central Basin predominantly from the westerly directions. Wind analysis was performed to quantify the wind climate in the area, and for development of extreme winds to be used as coastal and structural engineering design criteria. Wind data were collected from the Alameda Naval Air Station (NAS) anemometer, from which more than 60 years of data are available. The Alameda NAS station is suitable for wind-wave generation due to its long record and location in the Central Bay which is representative of winds generating waves over-water, in particular the strong SE winds that generated design waves of interest in Central Basin.

Figure 2 shows the distribution of measured wind speed and direction at Alameda NAS in the form of a wind rose. The data show that winds are most commonly from the west. The Alameda NAS hourly wind records were analyzed and the largest measured wind events were extracted. These extreme events were fit to a Weibull distribution, and sustained wind speeds were predicted for extreme events with recurrence intervals ranging from 2 to 100 years from all directions. Figure 3 shows the predicted extreme wind speeds for all return periods and directions.

Figure 2. Wind speed and direction distribution (wind rose) at Alameda NAS wind station

5

10

15

20

25

30

210

60

240

90270

120

300

150

330

180

0

Direction of Origin, deg T

Fre

quency o

f O

ccurr

ence,

%

>15

10 ≤15

7.5 ≤10

5 ≤7.5

2.5 ≤5

0 ≤2.5

Wind Speed [mph]

5

10

15

20

25

30

210

60

240

90270

120

300

150

330

180

0

Direction of Origin, deg T

Fre

quency o

f O

ccurr

ence,

%

>15

10 ≤15

7.5 ≤10

5 ≤7.5

2.5 ≤5

0 ≤2.5

Wind Speed [mph]


Figure 3. Extreme sustained wind speed and direction for return periods between 2 and 100 years

2.3. Wind-Waves

The wind extreme events developed in Section 2.2 were used to develop storm waves at the project site. Wind-wave growth and transformation modeling was performed using the two-dimensional spectral model SWAN (Holthuijsen et al., 2004). Figure 4 shows the SWAN input bathymetry for San Francisco Bay (left) constructed using historical data (U.S. Army Corps of Engineers, NOAA) as well as recent survey data, and a close-up of the model bathymetry near the project site (right) which included June 2013 multibeam survey data (eTrac Engineering 2013).

Figure 4. Wind-wave modeling domain for San Francisco Bay (left) and nearshore domain at project site (right)


The results of the SWAN model included spatial distributions of significant wave height (approximately the average of the highest one-third of the waves) and peak wave period, as well as other parameters. The extreme winds were used as input into the San Francisco Bay model for events with return periods of 100 years from all directions. Modeling was performed at MHHW tidal elevation to produce conservative wave conditions. Model testing indicates slightly lower extreme wave heights at MLLW tidal elevation.

Figure 5 shows example wind-wave growth and transformation modeling results (significant wave height) for 100-year winds from east-southeast, which generates the largest waves at the site. Figure 6 shows the same results with a close-up view of Central Basin. These results are based on the conservative assumption that Wharf-8 and the BAE facilities do not limit wave penetration to the project area. This scenario results in significant wave heights varying from 2.5 to 3.9 feet in the remediation area with peak wave period 5.2 seconds.

Figure 5. 100-year significant wave heights on Bay


Figure 6. 100-year significant wave heights in project area

2.4. Tidal Currents and Sedimentation

Tidal current and sediment transport analysis was performed at the project site to determine likely conditions at the proposed Crane Cove Park Beach, current speeds for design of remediation area alternatives, and to develop tools for conducting various impact analyses.

2.4.1. Tidal Current Model Setup and Validation

Tidal currents were evaluated on a Bay-wide scale using the depth-averaged finite volume fully unstructured hydrodynamic model MORPHO (Kolomiets et al., 2009). The model simulates water level and current velocity fluctuations generated by forcing from tides, winds and waves. The model was forced with predicted tidal constituents in the Pacific Ocean (LeProvost et al., 1994), and covers the entire San Francisco Bay with some extension upstream into the Sacramento and San Joaquin Rivers. No river flows were included as they have a negligible effect on flows in Central Basin. Figure 7 shows the majority of the modeling domain, with the exception of the areas far offshore of the Bay. Figure 8 shows snapshots of the tidal current speeds and directions around Central Basin during peak ebb (top) and flood (bottom) currents.


Figure 7. Tidal current modeling domain (Pacific Ocean extents not fully shown)

Sediment transport was modeled using a cohesive sediment excess shear formulation which computes erosion and deposition based on an erosion rate parameter and critical shear values for erosion and deposition. No artificial sediment inputs were included; therefore all sediment entering Central Basin areas was suspended in other parts of the Bay within the modeling domain.

Cursory tidal current model validations were performed using predicted tides at Alameda and a peak ebb current speed measured at Wharf 8 via boat with tracers and GPS units. Figure 9 shows the validation with predicted tides at Alameda (top) which were readily available, and the observed current velocity at Wharf 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.


Figure 9. Validation of tidal current model with predicted tides at Alameda (top) and observed current near Wharf 8 (bottom)

2.4.2. Measured Sedimentation Analysis

Analysis of measured sedimentation in Central Basin was performed using hydrographic surveys. Surveys from 1998, 1999 and 2013 were available for analysis. Given the small changes that occurred between 1998 and 1999, only the differences in the 1999 and 2013 surveys were used for the analysis. The outer dredging area was apparently maintained during that time, hence sedimentation rates in that area cannot be calculated.

Figure 10 shows the two hydrographic survey datasets used in the analysis, with 1999 being taken from a Port of San Francisco survey chart and the 2013 from a multibeam by eTrac Engineering (eTrac Engineering 2013). Sedimentation rates were calculated using the volume of sedimentation in each of several zones, broken down by the locations of previous dredging areas.


Figure 11 shows the sedimentation rates measured between the two surveys in inches per year. Generally, the sedimentation rates vary between 1 and 9 inches per year, largely depending on depth and location. Deeper areas farther east were subject to the highest sedimentation rates.

Figure 10. Hydrographic survey data used in measured sedimentation analysis, 1999 (top) and 2013 (bottom)

Figure 11. Measured sedimentation rates in Central Basin

2.4.1. Sedimentation Model Calibration

Sediment transport/morphology model calibration was performed by simulating one month of tidal currents, and allowing the Bay-wide model to pick up sediment on its own and transport around San Francisco Bay, and transport the sediment into Central Basin. Model calibration results show an overall excellent match in terms of volumes of sediment deposited into the various zones in Central Basin.


Figure 12 shows the model predicted sedimentation (one month results scaled linearly to one year), and callouts indicating the measured rates. Overall, the predicted sedimentation rates from the calibration exercise are slightly higher than the measured rates. The calibration resulted in a reliable tool for evaluation of sedimentation in Central Basin following implementation of various potential projects.

Figure 12. Model predicted sedimentation rates in Central Basin, with measured rates noted in white boxes

3. Sediment Remediation Concept Design

The POSF proposes to remediate an area of known contaminated sediment in Central Basin near the site of the proposed Crane Cove Park. The proposed remediation consists of capping the sediment using a rock cap and sheetpile wall to protect the cap from strong tug-induced bottom velocities that may exist at the site in the future. Figure 13 shows the proposed remediation area boundary provided by the POSF. The remediation design concepts were all required to contain all sediments within this polygon subject to 100-year design conditions.


Figure 13. Proposed remediation area boundary (hatched area)

3.1. Design Criteria

Design criteria for the remediation (capping) include storm waves and propeller wash bottom velocities. Storm wave conditions developed in Section 2 were evaluated and 100-year storm significant wave heights ranging from 2.6 to 3.9 feet with peak period 5.2 seconds were selected for design. Figure 14 shows the storm significant wave heights used for sizing the rock cap materials and where they occur in the area.

Propeller wash modeling was performed using the commercial CFD code FLOW3D (Flow Science 2014). FLOW3D is a volume of fluids three-dimensional general purpose hydrodynamic code used for a variety of hydraulic processes. The tug Delta Billie was used as the prototype vessel, and assumed to operate in a dredged area that does not presently exist but may in the future (personal communication with BAE, 2014). Delta Billie was used as the design tug boat as it was reported to be the most powerful tug (maximum thrust) likely to be used at the terminal (personal communication with BAE, 2014).

Table 3 provides the particulars of the tug. The tug was assumed to operate a maximum power and direct the propeller wash directly at the remediation area. Figure 15 shows a semi-steady state bottom velocity distribution generated by the tug.


Figure 14. Storm wave heights (significant wave heights) chosen for remediation area design (does not include effects of proposed sheetpile wall)

Table 3. Tug Particulars for Propeller Wash Modeling

Vessel Particular Value

Tug Length 100 feet

Tug Beam 40 feet

Tug Draft 19.0 feet

Propeller Diameter 9.18 feet

Bollard Pull 94 Tons

Prop. Dist. Below Water Level 14.4 feet

Power Delivered 6,800 hp

Figure 15. Bottom velocities generated by the tug Delta Billie after reaching approximately steady flow conditions


3.2. Remediation Concept Design

The remediation area was broken into two sections; Phase 1 at the western end, and Phase 2 at the eastern end. Storm waves govern remediation area armoring requirements for the Phase 1 area. In the Phase 1 area, the recommended cap would consist of at least a 1.5-ft thick layer of armor stone, with stone size six inches or more in diameter and with a total cap thickness of at least two feet. This recommendation assumes that regular maintenance is conducted to ensure that the minimum cap thickness is maintained. The two-foot initial cap thickness was estimated as a reasonable minimum constructible thickness to accommodate the armor stone and smaller bedding stone. In the Phase 1 area where the Crane Cove Beach is to be installed, other considerations may apply which could result in a lower cap thickness in those sub- beach areas. If the beach were to be installed over the cap, and specific beach sand maintenance requirements were in place, a smaller cap thickness could be acceptable. Specific details on the rock specifications and layering for the Phase 1 area should be developed during preliminary and final engineering design.

Assuming BAE Systems widens the nearby berth and tugs can access the area adjacent to the remediation area, analysis indicates that a rock cap is not feasible in the Phase 2 area without further protection from the propeller wash. Therefore, a breakwater concept was developed in coordination with POSF and analyzed. Figure 16 shows the required armor stone sizes calculated with FWERI (2005) that are required to resist tug-induced propeller wash after installation of the breakwater. The calculated rock sizes take into account the spatially variable bottom velocities and spatially variable bottom slopes. It should be noted that the breakwater shown here was a submerged toe-wall; however, the POSF prefers a full-height emergent structure. Analysis indicates that with the breakwater installed, the recommended armor stone size is at least 9-12 inches with a total cap thickness of at least three feet as a practical, constructible minimum.

While not specifically evaluated in the analysis, if BAE Systems does not widen the adjacent berth, it appears that insufficient space and depth exists for large tugs to maneuver close to the Phase 2 remediation area. In this case, it is possible that storm waves would once again govern the design and a breakwater would not be required. Specific details on the rock specifications and layering for the Phase 2 area should also be developed during preliminary and final engineering design.

In all areas, placement of an additional cap width of 10 feet is recommended as sacrificial scour protection, in lieu of more invasive toe scour protection measures (i.e. toe embedment) to minimize disturbance of the contaminated sediments. Final scour protection/toe protection details should be developed during preliminary and final engineering design. All capping areas will include geotextile filter fabric, followed by a bedding layer of smaller material, followed by a double layer of armor stone.


Figure 16. Required armor stone diameter for stability under propeller wash forces

Appendix A provides concept design drawings describing the proposed remediation concept design. Appendix B provides a cost estimate for construction of the remediation design by M. Lee Corporation. The conceptual-level cost estimate was based on the following:

1. Conceptual Design Submittal plans, total of 5 sheets, prepared by Coast & Harbor Engineering dated 6/5/2014

2. Draft Geotechnical Study Report for Pier 70, total of 146 pages, prepared by AGS, dated May 2014

3. Email titled "central basin remediation - breakwater cost", detailing breakwater dimensions and material, dated 6/12/2014

4. Clarification with design team

Conceptual cost estimates were generated assuming that 1) Phase 1 and Phase 2 are constructed at the same time, and 2) Phase 2 is constructed approximately two (2) years after completion of Phase 1. The conceptual cost estimates are the following:

• Option 1: Phase 1 & Phase 2 Combined: $2,861,000

• Option 2: Phase 1 & Phase 2 Separately: $3,043,000

Further details on the assumptions and limitations included in the cost estimate can be found in Appendix B.


4. Impact Analyses

The potential removal of Wharf 8, construction of Crane Cove Park, and deepening of Dredge Units 1-3 to 35 feet (MLLW) were evaluated in terms of their potential impacts to other areas of Central Basin. Wharf 8 removal was evaluated in terms of changes in hydrodynamics, wave climate, and sedimentation. Potential impacts of Crane Cove Park Beach construction and deepening of Dredge Units 1-3 were evaluated in terms of changes in hydrodynamics and sedimentation.

4.1. Effects of Wharf 8 Removal on Waves in Central Basin

Wharf 8 is composed of a 1,300-ft long, 82-ft wide pile-supported pier running in the roughly north-south direction that is connected to land by a perpendicular 700-ft section of pier. The wharf has been out of use for many years. The north-south span is supported by rows of circular steel pile (3 wide) which are spanned by 3-ft steel girders running along the length of the pier. At high tide, the bottom of the girders could offer some protection from storm waves and the pile arrangement of the pier results in a “shadow” region of reduced tidal current velocity during ebb-tide. A 300-ft section of the wharf also has a vertical timber screen which could offer additional protection. Photos of the Wharf 8 structure and timber screen are shown in Figure 17.

Figure 17. View from north end of Wharf 8 looking south (left) and timber screen on Wharf 8 (right), looking west

Computational fluid dynamics modeling was performed to analyze the impact of removing Wharf-8 on the extreme wave climate of the central basin. The 100-year wave has wave height of 6.6 feet and peak period of 6.0 seconds which was used in the modeling to calculate transmission through Wharf 8. Figure 18 shows snapshots of the modeling results (wave profiles color contoured with pressures) over the course of a single wave period.


Figure 18. FLOW-3D storm wave transmission under/through Wharf 8

Time histories of the water surface elevation behind Wharf 8 were analyzed both with and without the structure in place to determine the relative levels of wave transmission through the structure, and whether the structure provides any significant wave protection due to the low-hanging breams. Results indicate that even at MHHW tidal elevation, when the wave crest does impact the down-standing beams on the wharf, there was 95% transmission below/through the structure. Kriebel (2004) was applied to determine the transmission across the timber screen section of the wharf. Using conservative assumptions regarding the timber screen draft and porosity (i.e., assumptions that limit transmission further), results still indicate greater than 90% wave transmission through the screen section. Based on the modeling and analysis results, it appears that removal of Wharf 8 will have little effect on the storm wave climate in Central Basin.

4.2. Effects of Wharf 8 Removal on Sedimentation in Central Basin

Wharf 8 affects tidal currents and sedimentation patterns in Central Basin. Therefore, changes in sedimentation patterns and rates should be expected was therefore estimated with the sediment transport model. Wharf 8 was previously included in the modeling; hence, an evaluation of the effects of its removal was made by removing the Wharf 8 representation from the model and performing an identical simulation in all other respects.

Figure 19 shows sedimentation rates before (left) and after (right) removal of Wharf 8. Clearly the removal of Wharf 8 affects sedimentation patterns in the area. In some areas the sedimentation rate is increased, and in some areas it is decreased, as flows more easily enter the Central Basin. This figure also shows the increase or decrease in annual sedimentation volumes predicted to occur following Wharf 8 removal in each of the delineated areas. The removal of Wharf 8 does result in a slight overall increase in sedimentation in the Central Basin; however, it is small. The overall increase in sedimentation volume in all zones shown is approximately


2,300 cubic yards per year. The primary change is a redistribution of sedimentation farther into the basin and farther south in the ship operations/drydock areas.

Figure 19. Sedimentation rates with Wharf 8 in place (left) and rates/changes in rates following Wharf 8 removal (right)

4.3. Effects of Crane Cove Park Beach Construction on Sedimentation in Central Basin

Crane Cove Park includes a beach design that will result in filling in a small portion of the southeast corner of Central Basin with sand. Hydrodynamic modeling was performed to determine if this relatively small change may affect tidal current or sedimentation patterns in Central Basin. Figure 20 shows modeling domain bathymetry before (left) and after (right) installation of the beach. Figure 21 shows sedimentation rates before (left) and after (right) installation of Crane Cove Park Beach. The beach installation does not significantly affect transport or sedimentation patterns in Central Basin.


Figure 20. Modeling domain bathymetry for existing conditions (left) and with installation of Crane Cove Park Beach (right)

Figure 21. Sedimentation rates before (left) and after (right) installation of Crane Cove Park Beach

4.4. Effects of Deepening Dredge Units 1-3 on Sedimentation in Central Basin

The POSF may perform deepening within Dredge Units 1-3 in Central Basin to allow deeper-draft vessels to use the ship repair and drydock facilities operated by BAE. Hydrodynamic and sedimentation modeling was also performed to determine if this change may adversely affect tidal current or sedimentation patterns in Central Basin. Figure 22 shows the modeling domain bathymetry before (left) and after (right) deepening to -37 feet (MLLW). Figure 23 shows sedimentation rates before (left) and after (right) the deepening operations. The deepening has a measurable impact on sedimentation rates within the basin, generally increasing sedimentation in all areas except a small zone in the center of the basin. The overall increase in sedimentation volume in all zones shown is approximately 8,300 cubic yards per


year. This additional sedimentation in the entire Central Basin area should be considered prior to the proposed deepening to confirm the economic benefit to the POSF.

Figure 22. Existing elevations around Dredge Units 1-3, and proposed deepening (right)

Figure 23. Sedimentation rates before (left) and after (right) deepening of Dredge Units 1-3

5. Conclusions

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

6. References

eTrac Engineering. 2013. June 2013 Multibeam Hydrographic Survey.

Flow Science. 2014. FLOW3D Computational Fluid Dynamics Model.

FWERI. 2005. Bulletin No. 88, Principles for the Design of Bank and Bottom Protection for

Inland Waterways.

Holthuijsen, L.H., Booij, N., Ris, R.C., Haagsma, I.J.G., Kieftenburg, A.T.M.M., Kriezi, E.E., Zijlema, M. and A.J. van der Westhuysen. 2004. SWAN Cycle III Version 40.31

User Manual.

Le Provost, C., Genco, M.L., Lyard, F., Vincent, P., and Canceil, P. 1994. Spectroscopy of

the World Ocean Tides from a Finite Element Hydrological Model. J. Geophysical research, 99, 24777-24798.

Kolomiets, P., Sorockin, M., Kivva, S. and M. Zheleznyak. 2008. MORPHO-UNS-PAR

Unstructured Hydrodynamic Model.

Kriebel, D. L. 2004. A Design Method for Timber Wave Screens. Coastal Engineering Conference (Vol. 29, No. 4, p. 3891). ASCE.

APPENDIX A

Remediation Concept Design Drawings

AST & H A R BORNG EE NG

APPENDIX B

Remediation Construction Cost Estimate By M. Lee Corporation

M Lee Corporation

PORT OF SAN FRANCISCO

CENTRAL BASIN REMEDIATION

SAN FRANCISCO, CA

BASED ON

CONCEPTUAL DESIGN

Owner:


Prepared for:

COAST & HARBOR ENGINEERING

155 Montgomery Street, Suite 301

San Francisco, CA 94104

Phone: 888-533-1267

Attention: Scott Fenical, PE

Email: [email protected]

Prepared by:

M LEE CORPORATION

Construction Management & Consulting

311 California Street, Suite 610

San Francisco, CA 94104

Phone: 415-693-0236

Attention: Martin Lee, PE, CPE

Email: [email protected]

Date: 10/03/20141112 Central Basin Remediation Conceptual Estimate 20141003.xlsx

Prepared for: Coast and Harbor Eng.

Prepared by: M Lee Corp Cover Page 1 of 9

M Lee Corporation


BASED ON

CONCEPTUAL DESIGN

Table of Contents: Page No.

1.0 Preamble (Basis of Estimate) 3-5

2.0 Estimate Summary 6

3.0 Estimate Details 7-9

Date: 10/03/2014


Prepared by: M Lee Corp Cover Page 2 of 9

M Lee Corporation



CONCEPTUAL ESTIMATE OF PROBABLE CONSTRUCTION COST

BASED ON CONCEPTUAL DESIGN

PREAMBLE (BASIS OF ESTIMATE) Date: 10/03/2014

A) Basis of Estimate:

This Estimate is based on the following:

1 Conceptual Design Submittal plans, total of 5 sheets, prepared by Coast & Harbor Engineering,

dated 6/5/2014

2 Draft Geotechnical Study Report for Pier 70, total of 146 pages, prepared by AGS, dated May

2014

3 Email titled "central basin remediation - breakwater cost", detailing breakwater dimensions and

material, dated 6/12/2014

4 Clarification with design team

B) General Scope of Work

The general scope is as follows:

Phase 1

Dredging of sediment in the bay and capping of shore with geotextile fabric & rock armor

Phase 2

Capping with geotextile fabric & rock armor and construction of a 80 ft high steel sheetpile

breakwater structure

C) Exclusions

The estimate specifically excludes the following items:

1 Permit and plan check fees

2 Administration costs such as bidding, advertising and contract award

3 Professional fees for architect, engineers, consultants, construction management and other soft

costs

4 Costs for third party independent soil testing, inspection and sample confirmation

5 Construction change orders

6 Cost escalation beyond the assumed construction schedule

7 Project reserve and project contingency

It is assumed that the above items, if needed, are included elsewhere in the owner's overall project

budget.

D) Assumptions & Qualifications

1 This estimate presents costs for two different scenarios of construction:

Option 1: Phase 1 & Phase 2 completed during the same construction phase.

Option 2: Phase 1 & Phase 2 completed separately and independently, with Phase 2 construction

starting approximately 2 years after completion of Phase 1.

Work is assumed to be done during normal working hours

2 Schedule

Option 1: Based on a construction period of 5 months from June 2015 to November 2015 for

completion of both Phases.


Prepared by: M Lee Corp 1.0 Preamble Page 3 of 9

M Lee Corporation






Option 2: Based on a construction period of 5 months from June 2015 to November 2015 for

Phase 1 and a construction period of 5 months from June 2017 to November 2017 for Phase 2

3 The estimate is based on the following:

Quantities for the armor layer include a 10 ft wide sacrificial toe area

Assumed riprap / rock armor density of 1.8 tons/cy

Sediment removal in front of Slipway 4 done by clamshell on barge during high tide

Assumed dredged sediment density of 1.4 tons/cy

Assumed dredged sediment to be Class I RCRA hazardous waste, to be transported and disposed

275 miles from site

4 The estimate is based on estimated prices current as of June 2014, with four to five responsible and

responsive bids under a competitive bidding environment for a fixed price lump sum contract (a

fair market condition).

Note: Experience indicates that fewer bidders may result in higher bids, and conversely more

bidders may result in more competitive bids. Therefore it is important to obtain as many bids as

possible.

The following table provides a general guideline for probable impacts due to number of bids:

1 bid +15% to +40%

2-3 bids +8% to +12%

4-5 bids -4% to +4%

6-7 bids -7% to -5%

8 or more bids -12% to -8%

5 The following is a list of some items that may affect the cost estimate:

Modifications to the scope of work or assumptions included in this estimate

Unforeseen sub-surface conditions

Special phasing requirements

Restrictive technical specifications or excessive contract conditions

Any specified item of equipment, material, or product that cannot be obtained from at least three

different sources

Any other non-competitive bid situations

6 The estimate represents M Lee Corp's opinion of probable construction costs based on current

market conditions and the assumptions and qualifications in this Preamble

7 The estimate is intended to be a determination of fair market value for the project construction. It

is not a prediction of low bid. Since we have no control over market conditions and other factors

which may affect the bid prices, we cannot and do not warrant nor guarantee that bids or ultimate

construction costs will not vary from the cost estimate. We make no other warranties, either

expressed or implied, and are not responsible for the interpretation by others of the contents herein

the cost estimate.

8 Unit costs include costs for material, labor, equipment, sales tax, and contractor's markup.



M Lee Corporation






9 Based on a projected cost escalation at 4.5% per year to the assumed mid-point of construction is

included in the unit cost of the estimate.

D) Basis of Pricing

In pricing the estimate, we have made references to the following sources for cost data:

1 Historical cost data of similar projects

2 2014 RS Means Building Construction Cost Data by RS Means

3 2014 RS Means Heavy Construction Cost Data by RS Means

4 2014 National Construction Estimator by Craftsman

5 Construction Economics in Engineering-News-Record (ENR)

6 Walker's Building Estimator's Reference Book by Frank R. Walker Company

Based on the above cost sources, our analysis of the project specific requirements and our

judgment of the current market conditions, we have determined the unit costs specifically for this

project.

E) Abbreviations used in the estimate:

CF = cubic foot

CY = cubic yard

(E) = existing

EA = each

LB = pound

LF = linear foot

LOC = location

LS = lump sum

MTH = months

(N) = new

NIC = not in contract

PR = pair

SF = square foot

TN = ton



M Lee Corporation





ESTIMATE SUMMARY

Date: 10/03/2014

DESCRIPTION

Estimated

Cost $

Option 1: Phase 1 & Phase 2 Combined 2,861,000

Option 2: Phase 1 & Phase 2 Separately 3,043,000

Phase 1: Dredging of sediment in the bay and capping of shore with

geotextile fabric & rock armor

Phase 2: Capping with geotextile fabric & rock armor and

construction of a 80 ft high steel sheetpile breakwater structure

Prices are based on 4 to 5 competitive bids escalated to

assumed mid-point of construction

It is important to read the attached "Preamble" and "Estimate Details"

for assumptions, exclusions, qualifications and scope of work


Prepared by: M Lee Corp 2.0 Estimate Summary Page 6 of 9

M Lee Corporation





ESTIMATE DETAILS Date: 10/03/2014

Line Component Description Quantity Unit Unit Cost

$

Estimated

Cost $

2 Option 1: Phase 1 & Phase 2 Combined

3

4 Silt curtain, 5' H 800 LF 18.00 14,400

5 Remove debris & miscellaneous structures 38,000 SF 2.00 76,000

6 Remove (E) concrete structures 1 LS 10,000.00 10,000

7

8 Phase 1

9 Dredging

10 Mobilize clamshell on barge 1 LS 30,000.00 30,000

11 Dredge 822 CY 35.00 28,770

12 Haul-off of contaminated dredged material 1,151 Ton 100.00 115,100

13 Disposal of contaminated material, Class I RCRA 1,151 Ton 150.00 172,650

14

15 2 ft thick rock cap

16 Geotextile fabric 19,724 SF 1.50 29,586

17 6" bedding layer 365 CY 100.00 36,500

18 18" armor layer 1,972 Ton 80.00 157,760

19

20 Phase 2



23 12" bedding layer 421 CY 100.00 42,100

24 24" armor layer 1,514 Ton 80.00 121,120

25



28 6" bedding layer 110 CY 100.00 11,000

29 18" armor layer 594 Ton 80.00 47,520

30

31 Breakwater wall

32 Mobilize pile driver on barge 1 LS 50,000.00 50,000

33 Galvanized steel sheet pile, 60' embed, 20' exposed

height, 80' H total

7,200 SF 89.00 640,800

34 Cast-in-place concrete cap 90 LF 637.00 57,330

35

36 Option 1: Phase 1 & Phase 2 Combined - Subtotal 1,666,576

37

38 Option 1 Total Direct Cost 1,666,576

39 Design / Estimate Contingency 30% 499,973

40 General Contractor's General Conditions 16% 346,648

41 Bonds and Insurances 2% 50,264

42 Overhead and Profit 6% 153,808

43 Subtotal 2,717,267

44 Cost Escalation to Mid-point of Construction August 2015

@ 4.5% per Year

5.30% 144,015

45

46 OPTION 1 TOTAL ESTIMATED CONSTRUCTION COSTS 2,861,283

47 rounded 2,861,000


Prepared by: M Lee Corp 3.0 Estimate Details Page 7 of 9

M Lee Corporation







$

Estimated

Cost $

48

49 Option 2: Phase 1 & Phase 2 Separately

50

51

52 Phase 1

53 Silt curtain, 5' H 370 LF 18.00 6,660


55

56 Dredging

57 Mobilize clamshell on barge 1 LS 30,000.00 30,000

58 Dredge 822 CY 35.00 28,770

59 Haul-off of contaminated dredged material 1,151 Ton 100.00 115,100

60 Disposal of contaminated material, Class I RCRA 1,151 Ton 150.00 172,650

61



64 6" bedding layer 365 CY 100.00 36,500

65 18" armor layer 1,972 Ton 80.00 157,760

66

67 Option 2: Phase 1 Subtotal 617,026

68

69 Option 2: Phase 1 Direct Cost 617,026





74 Subtotal 1,006,030


@ 4.5% per Year

5.30% 53,320

76

77 OPTION 2 PHASE 1 ESTIMATED CONSTRUCTION COSTS 1,059,349

78

79

80 Phase 2

81 Silt curtain, 5' H 680 LF 18.00 12,240


83 Remove (E) concrete structures 1 LS 10,000.00 10,000

84



87 12" bedding layer 421 CY 100.00 42,100

88 24" armor layer 1,514 Ton 80.00 121,120

89



92 6" bedding layer 110 CY 100.00 11,000

93 18" armor layer 594 Ton 80.00 47,520

94

95 Breakwater wall



M Lee Corporation







$

Estimated

Cost $

96 Mobilize pile driver on barge 1 LS 50,000.00 50,000

97 Galvanized steel sheet pile, 60' embed, 20' exposed

height, 80' H total

7,200 SF 89.00 640,800

98 Cast-in-place concrete cap 90 LF 637.00 57,330

99

100 Option 2: Phase 2 Subtotal 1,054,050

101

102 Option 2: Phase 2 Direct Cost 1,054,050





107 Subtotal 1,718,575


@ 4.5% per Year

15.40% 264,660

109

110 OPTION 2 PHASE 2 ESTIMATED CONSTRUCTION COSTS 1,983,235

111

112 OPTION 2 TOTAL ESTIMATED CONSTRUCTION COSTS 3,042,584

113 rounded 3,043,000



technical report coastal engineering analysis, remediation ... · technical report coastal...

Documents