Appendix I Sediment Spillage

APPENDIX I EVALUATION OF EXPECTED SEDIMENTATION EXPOSURE IN THE OFFSHORE OF PORT EVERGLADES AS A RESULT OF THE PORT EVERGLADES PROJECT

PORT EVERGLADES, FLORIDA PROJECT

Port Everglades, Florida Project December 2020 I‐i Appendix I Sediment Spillage

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Port Everglades, Florida Project December 2020 I‐ii Appendix I Sediment Spillage

Table of Contents I INTRODUCTION ‐ EVALUATION OF EXPECTED SEDIMENTATION EXPOSURE IN THE OFFSHORE OF PORT EVERGLADES AS A RESULT OF THE PORT EVERGLADES PROJECT I‐1 I.1 Dredge Plume Development ...... I‐1 I.2 Sediment Quantities and Characteristics ...... I‐3 I.3 Dredge Equipment ...... I‐7 I.4 Spillage Estimates ...... I‐7 I.5 Sediment Deposition Distribution ...... I‐9 I.5.1 Exponential Distributions and Dilution for CSD and Overflow ...... I‐9 I.5.2 Representative Currents Fields and Distributions ...... I‐10 I.5.3 Release Depths and Settling Distances ...... I‐12 I.5.4 Exponential Distributions and Dilution for Mechanical Dredging ...... I‐14 I.6 Sediment Thickness Exposure ...... I‐14 I.6.1 Scenario 1 ...... I‐15 I.6.2 Scenario 2 ...... I‐20 I.6.3 Scenario 3 ...... I‐25 I.6.4 Scenario 4 ...... I‐29 I.6.5 Direct Impacts ...... I‐34 I.7 Summary ...... I‐34 I.8 References ...... I‐38 I.9 Addendum 1 ‐ Evaluation of Expected Sedimentation Exposure Offshore of Port Everglades as a Result of the Port Everglades Deepening Project ...... I‐40 I.9.1 Introduction ...... I‐40 I.9.2 Sediment Quantities and Characteristics ...... I‐40 I.9.3 Dredge Equipment ...... I‐43 I.9.4 Spillage Estimates ...... I‐43 I.9.5 Sediment Deposition Distribution ...... I‐44 I.9.6 Summary ...... I‐62 I.9.7 References ...... I‐63 I.10 Addendum 2 – Distance Tables with Statistics ...... I‐65

List of Tables Table I‐1. Summary of sediment quantities, percent fines, and total quantities of fines...... I‐6 Table I‐2. Summary of dredge spill information...... I‐9 Table I‐3. Distance clay particles may travels before reaching a depth of 15 m for various release depths, fall velocities and current speeds...... I‐13

Port Everglades, Florida Project December 2020 I‐iii Appendix I Sediment Spillage

Table I‐4. Distance north and south of the channel of sedimentation thickness under scenario 1: a CSD with overflow of various quantities at various overflow release depths for segments 1 (A), 2 (B), and 3 (C)...... I‐16 Table I‐5. Estimates of Exposure acreage for each benthos category for a given pre‐defined value of sedimentation exposure for SCENARIO 1: a CSD with overflow at 3.0 m water depth...... I‐19 Table I‐6. Distance north and south of the channel of sedimentation thickness under scenario 2: a CSD with barge decanting at 3.0 m water depth for segments 1 (A), 2 (B), and 3 (C).I‐21 Table I‐7. Estimates of Exposure acreage for each benthos category for a given pre‐defined value of sedimentation exposure for Scenario 2: a CSD with barge decanting at 3.0 m water depth...... I‐24 Table I‐8. Distance north and south of the channel of sedimentation thickness under scenario 3: a CSD with direct pump to offshore disposal for segments 1 (A), 2 (B), and 3 (C)..... I‐26 Table I‐9. Estimates of Exposure acreage for each benthos category for a given pre‐defined values of sedimentation exposure for Scenario 3: a CSD with direct pump to offshore disposal...... I‐28 Table I‐10. Distance north and south of the channel of sedimentation thickness under scenario 4: mechanical dredge with barge decant for segments 1 (A), 2 (B), and 3 (C)...... I‐30 Table I‐11. Estimates of Exposure acreage for each benthos category for a given pre‐defined value of sedimentation exposure for Scenario 4: mechanical dredge with barge decant. . I‐33 Table I‐12. Direct Impacts in the Navigation Channel (not including side slope impacts)...... I‐34 Table I‐13. Summary of assumptions...... I‐35 Table I‐14. Summary of scenarios and spill volumes...... I‐37 Table I‐15. Summary of sediment quantities, percent coarse, and total quantities of coarse material...... I‐42 Table I‐16. Summary of Dredge Spill Information...... I‐44 Table I‐17. Distance sand particles may travel before reaching a depth of 15 m for various release depths, fall velocities and current speeds...... I‐47 Table I‐18. Summary of assumptions...... I‐48 Table I‐19. Distance north and south of the channel of sedimentation thickness under scenario 1: a CSD with overflow of various quantities at various overflow release depths for segments 1 (A), 2 (B), and 3 (C)...... I‐51 Table I‐20. Estimates of Exposure acreage for each benthos category for a given pre‐defined value of sedimentation exposure for SCENARIO 1: a CSD with overflow at 3.0 m water depth...... I‐53 Table I‐21. Distance north and south of the channel of sedimentation thickness under scenario 2: a CSD with spill at the cutterhead for segments 1 (A), 2 (B), and 3 (C)...... I‐54 Table I‐22. Estimates of Exposure acreage for each benthos category for a given pre‐defined value of sedimentation exposure for Scenario 2: a CSD with spill at the cutterhead...... I‐57 Table I‐23. Distance north and south of the channel of sedimentation thickness under scenario 4: mechanical dredge with barge decant for segments 1 (A), 2 (B), and 3 (C)...... I‐58 Table I‐24. Estimates of Exposure acreage for each benthos category for a given pre‐defined value of sedimentation exposure for Scenario 4: mechanical dredge...... I‐61 Table I‐25. Summary of scenarios and spill volumes for coarse sediment...... I‐62 Table I‐26. Distance north and south of the channel of sedimentation thickness under scenario 1: a CSD with overflow at a release depth of 3.0 m for segments 1 (A), 2 (B), and 3 (C) for fines (d50 < 0.062 mm)...... I‐65

Port Everglades, Florida Project December 2020 I‐iv Appendix I Sediment Spillage

Table I‐27. Distance north and south of the channel of sedimentation thickness under scenario 2: a CSD with barge decanting at 3.0 m water depth for segments 1 (A), 2 (B), and 3 (C) for fines (d50 < 0.062 mm)...... I‐66 Table I‐28. Distance north and south of the channel of sedimentation thickness under scenario 3: a CSD with direct pump to offshore disposal for segments 1 (a), 2 (b), and 3 (c) for fines (d50 < 0.062 mm)...... I‐68 Table I‐29. Distance north and south of the channel of sedimentation thickness under scenario 4: mechanical dredge with barge decant for segments 1 (a), 2 (b), and 3 (c) for fines (d50 < 0.062 mm)...... I‐70

List of Figures Figure I‐1. Processes in and around a dynamic plume from Dankers 2002...... I‐2 Figure I‐2. Processes in and around passive plumes from Dankers 2002...... I‐2 Figure I‐3. Location of 92 core borings taken at Port Everglades between 2016 and 2018...... I‐4 Figure I‐4. Example figure taken from SAJ EN‐G MFR (2017) showing intervals of unconsolidated sediments, typically fine grained, poorly graded sands (SP) with trace amounts of fine grained sediments (< 5%; primarily silt) between and within rock intervals...... I‐5 Figure I‐5. Example of a dilution factor used to adjust suspended sediment concentration to account for lateral spreading not depicted in centerline observations...... I‐10 Figure I‐6. Normalized Suspended sediment concentration versus distance for a sediment release at 20 ft water depth...... I‐13 Figure I‐7. Normalized suspended sediment concentration versus distance for mechanical dredging...... I‐14 Figure I‐8. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 1: a CSD with overflow at 3.0 m water depth...... I‐16 Figure I‐9. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 2: a CSD with barge decanting at 3.0 m water depth. I‐21 Figure I‐10. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 3: a CSD with direct pump to offshore disposal...... I‐25 Figure I‐11. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 4: mechanical dredge with barge decant. ... I‐29 Figure I‐12. Location of 92 core borings taken at Port Everglades between 2016 and 2018...... I‐41 Figure I‐13. Example of a dilution factor used to adjust suspended sediment concentration to account for lateral spreading not depicted in centerline observations...... I‐46 Figure I‐14. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 1: a CSD with overflow at 3.0 m water depth...... I‐50 Figure I‐15. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 2: a CSD with spill at the cutterhead...... I‐56 Figure I‐16. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 4: mechanical dredge...... I‐60

Port Everglades, Florida Project December 2020 I‐v Appendix I Sediment Spillage

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Port Everglades, Florida Project December 2020 I‐vi Appendix I Sediment Spillage

I INTRODUCTION ‐ EVALUATION OF EXPECTED SEDIMENTATION EXPOSURE IN THE OFFSHORE OF PORT EVERGLADES AS A RESULT OF THE PORT EVERGLADES PROJECT

This document summarizes an analytical estimate of sediment deposition resulting from the Port Everglades Deepening Project (PEDP). The method is based on representative sediment properties at the project site and associated fall velocities, measured current data from the site, sediment volume estimates, assumed dredge equipment, and estimated spillage rates and distributions of sediment concentration for various dredging techniques

I.1 Dredge Plume Development

All dredging operations introduce dredged sediment into the water column, increasing the suspended solids concentrations above the background concentration that would be present in the absence of dredging and generating a dredge‐induced suspended sediment plume. The size and location of the resulting plume are a function of the dredging operation, sediment characteristics, the local environment, and the amount of spillage. Spillage is the release or mobilization of sediments into the water column due to dredging and related activities. The plume behavior that results from spillage is a function of the release mechanism/location, sediment characteristics, hydrodynamics, and other physiochemical factors related to the material in the marine environment. Exposure of resources near the plume are directly related to suspended sediment release and resulting deposition.

The particle size characteristics of the sediments released into the water column depend on the in situ material dredged and the size and characteristics of particles generated when that material is subjected to dredging (Kemps and Masini, 2017).

Plumes are generally classified as dynamic or passive with a transitional phase in‐between. Dynamic plumes originate from discharges of high concentration sediment‐water suspensions that are significantly denser than the surrounding waters (Kemps and Masini, 2017; Figure I‐1). Dynamic plumes descend rapidly towards the seabed and then spread across the seabed as a passive plume (Dankers, 2002). This transition may occur in the water column and/or after the dynamic plume has impacted the seabed and formed a spreading bed plume. For a dynamic plume, the bulk behavior of the water‐sediment suspension, rather than the settling velocity of the individual particles is important (Winterwerp, 2002). The settling velocity of a dynamic plume is relatively large and therefore the impact zone is relatively small and confined near the source (Dankers, 2002).

Port Everglades, Florida Project December 2020 I‐1 Appendix I Sediment Spillage

Figure I‐1. Processes in and around a dynamic plume from Dankers 2002.

Passive plumes consist of low suspended sediment concentration mixtures that have minimal density or momentum differences relative to the surrounding seawater (Kemps and Masini, 2017; Figure I‐2). Passive plumes arise due to stripping of particles from dynamic plumes by entrainment caused by turbulence. When the current velocities are strong enough, the plume will mix entirely with the surrounding water (Dankers, 2002). As such the sediment transport in passive plumes is governed by the ambient hydrodynamics, the vertical settling velocity of the suspended particles and by particle deposition or resuspension at the sea bed (Kemps and Masini, 2017). The sediment concentrations within a passive plume are thus relatively low (generally less than 500 mg/L). Both types of plumes are subject to resuspension processes which may be captured in the overall spill rate.

Figure I‐2. Processes in and around passive plumes from Dankers 2002.

Given that dynamic plumes tend to settle out very near the source and that many of the sources from dredging operations produce dilute suspensions, passive plumes which are dictated by settling velocities

Port Everglades, Florida Project December 2020 I‐2 Appendix I Sediment Spillage and ambient hydrodynamics are assumed here. This provides a conservative assumption for areal extent of sedimentation exposure as this estimate assumes all spilled sediment forms the far field passive plume whereas a proportion of that spill will form a dynamic plume and settle in the near field very close to the source.

I.2 Sediment Quantities and Characteristics

The sediment characteristics of the rock and overburden material at Port Everglades were defined in Schroeder (2018) and through analysis of additional geotechnical data by the Geosystems Branch, Engineering Division of United States Army Corps of Engineers (USACE) Jacksonville District (SAJ EN‐G). This analysis was carried out for the various segments of PEDP: the Outer Entrance Channel (OEC), the Inner Entrance Channel (IEC), Main Turning Basin (MTB) / Widener, the Southport Access Channel (SAC), and the Turning Notch (TN). The evaluation focused on the amount of fines (silt and/or clay size materials) that may be generated during dredging of rock and overburden sediment present at the project site for the planned project depths. A follow on analysis of coarse grained material is provided as an addendum to this report. This evaluation consisted of review of ninety two core borings drilled in the project area between 2016 and 2018 (Figure I‐3) as well as historical logs for over two hundred historical borings dating back to the 1950s.

Table I‐1 summarizes the estimated percentage and volume of the fine grained material for both rock and overburden sediment within the project segments. The estimated percentage of bedrock volume consisting of “soft” cement matrix or fines ranges from 8.0% within the IEC and MTB up to 18.6% within the OEC. These percentages are based on horizontal and vertical mapping of limestone and/or sandstone bedrock within each project segment and evaluation of the geotechnical logs in each area for lithologic characteristics, hardness, degree of weathering, and other physical characteristics, as well as review of other drilling and rock related data (standard penetration test or SPT blow counts, coring time, rock quality designation or RQD, geotechnical testing etc.). Resistant, hard rock intervals were assigned a fines (silt and/or clay) percentage of 8%, which is based on the average fines percentage of the 2017 United States Army Corps of Engineers Engineering Research and Development Center (ERDC) crushed rock gradation samples collected via a PQ wireline core barrel drilling system. Rock intervals containing softer, fine grained, matrix materials were assigned a fines percentage of approximately 34%. This higher fines percentage represents the average percent fines (silt and clay) calculated for the 2018 ERDC crushed rock gradation samples collected via SPT split spoon samples within the OEC. A similar fines percentage (35%) was estimated for the shallow, “soft” limestone intervals within the Widener and Turning Notch areas based on visual logging of SPT rock samples from those areas. Rock samples collected via SPT typically represent softer, less resistant rock in comparison to the harder rock intervals which require core drilling to collect rock samples. Intervals of unconsolidated sediments, typically fine grained, poorly graded sands (SP) with trace amounts of fine grained sediments (< 5%; primarily silt), were encountered between and within rock intervals based on the boring logs as shown in Figure I‐4. The volume of fines present in these sediment intervals was calculated and included with the fines volume calculated for the overall rock interval in which the layers were contained.

The estimated percentage of fines within the overlying overburden/sediment layer within the project footprint ranges from 3.3% within the IEC up to 54% within the Southport Access Channel (SAC) and the Turning Notch. The OEC, like the IEC, exhibits a relatively low percentage of fines (5.4%). The fine grained sediment percentages within the overburden increase within the inner segments of the project area (MTB, SAC, etc.). Sediment samples collected within each project segment were tested by SAJ to determine the gradation (particle size distribution) for each sample.

Port Everglades, Florida Project December 2020 I‐3 Appendix I Sediment Spillage

The EN‐G evaluation efforts are summarized in the July 2017 Memorandum For Record (MFR), Review of PD‐EC Dredging Scenarios, subsequent additional evaluations of the OEC based on ERDC laboratory testing data (2017 & 2018), and further refinement of mapped rock hardness areas within the project segment.

Analysis of the sediment fall velocity is reported in Schroeder (2018) for various size classes. For this analysis all the particles were assumed to be clay and silt size particles with a fall velocity of 0.0002 m/s based on Schroeder (2017, 2018). This assumption results in the particles traveling a greater distance away from the source before settling. To test the sensitivity to this assumption, a separate fall velocity of five times that above (0.001 m/s) was also analyzed and has been folded into the results presented here. This fall velocity is still representative of fine particles that are expected to be dredged during the project. As a result of the higher settling velocity, the predicted areal extent of plume migration and deposition will decrease, but thicknesses will increase.

Figure I‐3. Location of 92 core borings taken at Port Everglades between 2016 and 2018.

Port Everglades, Florida Project December 2020 I‐4 Appendix I Sediment Spillage

Figure I‐4. Example figure taken from SAJ EN‐G MFR (2017) showing intervals of unconsolidated sediments, typically fine grained, poorly graded sands (SP) with trace amounts of fine grained sediments (< 5%; primarily silt) between and within rock intervals.

Port Everglades, Florida Project December 2020 I‐5 Appendix I Sediment Spillage

Table I‐1. Summary of sediment quantities, percent fines, and total quantities of fines.

Bedrock Overburden / Sediment

Estimated Calculated Percentage of Estimated Rock Estimated Rock Rock Removal Volume Calculated Overburden / Removal Volume consisting Overburden / Estimated Percent Sediment Volume Consisting of of Fines/Cement Sediment of volume consisting (cubic Fines/Cement Matrix Volume Overburden/Sediment of fines Location yards) Matrix (cubic yards) (cubic yards) Consisting of Fines (cubic yards)

Outer Entrance Channel (OEC) 782,330 18.6% 145,513 274,732 5.4% 14,836

Inner Entrance Channel (IEC) 30,753 8.0% 2,460 276,940 3.3% 9,139

Widener ‐ Eastward Channel Expansion 648,521 16.0% 103,763 347,724 36.2% 125,876

Main Turning Basin ‐ Total (MTB‐Total) 164,469 8.0% 13,158 536,265 36.2% 194,128

Southport Access Channel Total 268,050 16.0% 42,888 1,303,450 54.0% 703,863

Turning Notch (Total) 486,972 10.0% 48,697 121,556 54.0% 65,640

Total 2,381,095 15.0% 356,480 2,860,667 38.9% 1,113,482

Port Everglades, Florida Project December 2020 I‐6 Appendix I Sediment Spillage

I.3 Dredge Equipment

It is anticipated that a mechanical clamshell dredge and/or a cutter suction dredge (CSD) will be used for the PEDP. These two types of equipment combined with confined blasting are the only types of dredging equipment capable of removing the rock found in the project area.

For mechanical dredges, fine sediment plumes are generally released in pulses during the lift phase of the dredging cycle. The plume is discontinuous from intermittent, discrete, very slow moving sources. Generally the spillage is distributed throughout the water column with significant biases toward the surface and near bottom. CSD‐related spillage sources that may contribute to dredge induced suspended sediment plumes are from the scow overflow and the rotating cutterhead. For the cutterhead spillage, the rotation rate, swing speed, cut depth, and sediment properties influence the amount of sediment suspended (J. Becker et al. 2015). The suspended sediment is generated close to the bed and a large portion will stay low in the water column and settle near the dredge (J. Becker et al. 2015). As the cutterhead works material is entrained into the suction line. The material that is not entrained is referred to as spillage and is broken into two categories: residual and resuspended (Mills and Kemps 2016). The resuspended material is that which contributes to the far field plume and is the focus here (not to be confused with resuspension of material far from the source due to hydrodynamics and sediment transport). The residual material refers to material that is rapidly deposited to the seabed. For both dredge types the residual material or coarse material (i.e., sands and gravels) is not a concern as it readily settles out very near the source given their high settling velocities.

I.4 Spillage Estimates

Data on the spillage rate as a percentage of fines within the total volume of excavated material varies from project to project, is often not reported or measured, and consensus values do not exist. As noted in Mills and Kemps (2016) relatively little has been published in relation to fines resuspension for CSDs cutting hard rock. As such pertinent literature was reviewed to consolidate published estimates and develop rates for this analysis. Kemps and Masini (2017) provided a summary report on estimates of the primary source term contributions for CSDs and for overflow from trailing suction hopper dredges (TSHD) on a number of projects in Western Australia. This is the most comprehensive collection of spillage source rate estimates. It consists of a number of spillage rates that vary based on the geological characteristics of the material and the dredge equipment type. These rates were mined from modeling studies submitted to review studies were dredging near sensitive resources was an issue.

Included in the Kemps and Masini (2017) analysis were a number of projects by the Danish Hydraulic Institute (DHI). DHI maintains a database that represents the average of thousands of measurements. These values were presented by Tom Foster and Josh Van Berkel in the 27 April 2018 Danish Hydraulic Institute (DHI) seminar “Proactive and Adaptive Measures for the Management of Coastal Development Induced Sediment Plume Impacts” and this information is included evaluations in this report.

Information on spillage rates from decanting, or the process of releasing supernatant water to increase a barge’s effective load, is scarce. Reine and Schroeder (2015) provide an estimate based on measurements taken during a mechanical dredging project in San Francisco Bay. They note that decanting discharges would increase sediment loss by no more that 0.1% (compared to sediment loss without decanting). They also note that if decanting is not allowed, then additional barges would be required to transport the

Port Everglades, Florida Project December 2020 I‐7 Appendix I Sediment Spillage equivalent amount of sediment leading to other environmental effects (i.e., an increased number of round trips and the associated additional fuel consumption and reduction of air quality associated with them). In this analysis there is a distinction between decanting and overflow. Overflow is a continual process of releasing material while filling a barge. Decanting in this analysis is a one‐time release after a barge has been filled and is a safety measure to ensure safe transport offshore. Based on a comparison of spillage rates between overflow and decanting, the sedimentation effects are negligible from decanting in comparison. An analysis of the excursion for a very fine particle released at the surface can be nearly 10 km before settling out. While these effects are not expected to impact sedimentation at that distance, they could result in a visible plume, especially in the waters of southeast Florida, which may be misconstrued as impacts extending well beyond a kilometer from the source due to decanting.

Based on the above, the spillage rates depicted in Table I‐2 were used in this analysis. For clamshell dredging (i.e. mechanical dredge) the spillage rate is estimated as 5% of the fines dredged based on the DHI database. This is considered a conservative estimate based on personal communication with ERDC dredging experts (personal communication: teleconference with Paul Schroeder and Don Hayes, 18 and 19 February 2020 with ERDC, 2020). They cite values generally less than 1%. The sediment is generally released during the up phase of the dredge cycle throughout the water column with a bias towards the near surface and near bottom. For this analysis the vertical distribution of the release is assumed to be 40% near the bed, 40% at the surface and 20% at mid‐depth to reflect the biases at the surface and bed. For CSD the main sources are at the draghead and within the overflow discharge from the scow/barge. The selected values are from various studies presented in Kemps and Masini (2017) and in‐line with those presented by DHI. For the rock, at the draghead the rate is estimated at 15% of the fines and corresponds to a study in Australia dredging hard rock (Kemps and Masini 2017). This is considered a conservative estimate (based on personal communication: teleconference with Paul Schroeder and Don Hayes, 18 and 19 February 2020 with ERDC, 2020). The rate at the draghead for the overburden is estimated as 7.5% of the fines and is based on DHI data and the Chevron Wheatstone Project in Onslow, Western Australia. ERDC guidance suggests using 1% as a conservative estimate of spillage at the draghead. The rates used herein are considered extremely conservative. For overflow the spill rate is 15% for both the rock and overburden material. This is the DHI developed rate and corresponds with the silt and clay size material dredged at the North Queensland Bulk Ports Corporation Port of Abbot Point in Queensland Australia (Kemps and Masini 2017). As mentioned above, examples of measurements from decanting are scarce. The estimate used in this analysis is based on Reine and Schroeder (2015) and is 0.1% for mechanical dredging. For cutterhead dredge where the fines are expected to be more readily in suspension due to a greater amount of water in the mixture, the decant estimate is 1% based on personal communication (personal communication: teleconference with Paul Schroeder and Don Hayes, 18 and 19 February 2020 with ERDC, 2020).

The introductory comments discussed the differences between the dynamic and passive plumes. At many of the assumed spill rates the resulting plumes are expected to yield a density flow which typically settles at the source and then slowly disperses. To provide a more conservative estimate, a passive plume which can spread much further is assumed in this analysis.

Port Everglades, Florida Project December 2020 I‐8 Appendix I Sediment Spillage

Table I‐2. Summary of dredge spill information.

Mechanical CSD – Draghead Barge ‐ Overflow Decant

Location Throughout 5 ft above the Various depths below water Near‐ water column bed surface Surface

(13.7 m depth) (3.0 to 7.6 m depth) (3.0 m depth)

Mech. / CSD

Spill Rate – 5 15 15 0.1 / 1.0 Rock

(% of fines)

Spill Rate – 5 7.5 15 0.1 / 1.0 Overburden

(% of fines)

I.5 Sediment Deposition Distribution

I.5.1 Exponential Distributions and Dilution for CSD and Overflow

Based on observations, the suspended sediment distribution decreases exponentially with distance from the source. The USACE Dredging and Dredged Material Management Engineer Manual (USACE 2015) provides notes and summaries of a number of projects exhibiting this behavior. Among the items listed and discussed in the manual are concentration and distance measurements for a number of projects in Appendix B. Figure B‐2 of this manual provides curves of suspended sediment concentrations versus distance from the source for projects with overflow, showing a return to background levels within approximately 1,200 m and to zero at 2,600 m. Similar plots for aggregate dredging in Spearman (2015) show an exponential decay and return to background within approximately 1,000 to 2,000 m. Nichols et al. (1990) show a similar decrease in concentration but a return to background levels further from the source at a distance of approximately 5,000 m and to zero around 5,700 m. There is a large difference in the overall extents likely due to the locations of measurements, but in terms of concentrations the observations are similar with most of the concentration confined near the source and only lower values measured at greater distances. These studies were not suspended solids from rock dredging nor were they from new work which would generally have lower resuspension rates (personal communication: teleconference with Paul Schroeder and Don Hayes, 18 and 19 February 2020 with ERDC, 2020). Unfortunately observations from rock dredging new work were not found in the literature. The result is that these spillage estimates and suspended sediment estimates are believed to represent conservative estimates compared to rock dredging.

For this analysis, the suspended sediment concentrations decay in USACE (2015) and Nichols et al. (1990) were taken since they share more similar sediment characteristics with the silt and clay size particles

Port Everglades, Florida Project December 2020 I‐9 Appendix I Sediment Spillage expected at Port Everglades. The sediment deposition was assumed to follow the distribution of the suspended sediment concentration. It is noted that a more appropriate metric may be the sediment mass as a function of distance. In the absence of those measurements USACE (2015) and Nichols et al. (1990) were both used as is and they were adjusted to account for dilution of the concentration laterally away from the plume axis. To accomplish the later the DREDGE model (Hayes and Je, 2000) was run under various representative scenarios (current speed and fall velocity) and the spread in the suspended sediment concentration laterally as a function of distance from the source was determined. DREDGE couples resuspension source models from the source with a Gaussian dispersion model (Kuo et al 1985, Kuo and Hayes 1991). An adjustment factor was developed based on the centerline concentration in relation to the total concentration (including lateral dispersion). In this way all the mass (including lateral spread / dilution) is accounted for and included in the centerline number. An example of a dilution factor as a function of distance from the source is shown in Figure I‐5.

The original and adjusted observations were normalized and scaled to the expected furthest distance a particle would travel (based on release depth as discussed below). In this way the shape of the distribution is preserved and it can be scaled so the area under the curve corresponds to the amount of sediment to be released within the expected distance a clay particle will travel while settling. The curves were fit to a representative exponential curve of the form: f(x) = a exp (b) + c exp (d). An example is shown below in Figure 6 for the normalized distributions for a particle released at a water depth of 6 m. USACE (2015) provides a range of concentrations versus distance; the following analyses generates three estimates based on the average value and the high and low values associated with the defined error bars (Est. 1, 2, and 3). Similarly, Nichols (1990) information yielded two estimates to cover the range in their data ‐ one based on the peak concentrations observed of a single cycle and the other based on the average of many peak concentrations versus distance measurements.

14 12 10 Factor

8 6 4 Dilution 2 0 0 2000 4000 6000 8000 10000 12000 Distance from Source (m)

Figure I‐5. Example of a dilution factor used to adjust suspended sediment concentration to account for lateral spreading not depicted in centerline observations.

I.5.2 Representative Currents Fields and Distributions

Nearshore current observations were used to estimate the distance that sediment particles would travel. Nova Southeastern University maintained an acoustic Doppler current profiler (ADCP) off Dania Beach in 11 m water depth from 25 June 1999 to 03 May 2013 (Soloviev et al. 2015). This data was analyzed and

Port Everglades, Florida Project December 2020 I‐10 Appendix I Sediment Spillage the peak current velocities from each tidal cycle were analyzed. A maximum period (starting on 20 July 2001, ~1 m/s surface current) was used to estimate the maximum extent clay size particles with a fall velocity of 0.0002 m/s would travel before settling to the bottom. This high flow period will provide maximum distance areal estimates. The high flow also produces maximum dilution, which is why the curves are adjusted for dilution as mentioned previously. Only a small fraction of the fines have a settling velocity as low as 0.0002 m/s so as previously mentioned a second, faster fall velocity of 0.001 m/s was also used. Due to the exponential shape of the distribution the response of sediment deposition is not always intuitive. In general the slower fall velocity and faster currents lead to sediment exposure further from the source. But they also tend to spread out the distribution so that exposure may be very minor compared to faster fall velocities and slower currents which keep sediment more confined to the source but with thicker deposition patterns. To test the sensitivity to the current speed an average (~ 0.25 m/s surface current) and a minimum period (~0.1 m/s surface current) of current speed were also analyzed. To account for these differences a total of sixty different estimates were analyzed for the hydraulic dredge scenarios: five distributions (three USACE (2015) and two Nichols et al. (1990)), two versions of those distributions (original and adjusted for dilution), three current distributions, and two fall velocities.

In order to quantify the amount of sediment available to scale to the above distributions, details on the offshore flow and the tidal exchange through the inlet were examined. Note, that in this application the term offshore is used to refer to waters seaward of the inlet jetties and beach (i.e. the coastal ocean waters). Soloviev et al. (2017), Carsey et al. (2016), Carsey et al. (2015), and Stamates et al. (2013) all examine the predominant current direction offshore of Port Everglades. They note that the further east the more predominant the northward directed current. Close to shore (within 1,800 m) the current is directed northward less than 50% of the time based on observations taken between 18 September 2015 and 12 November 2015. Further offshore (2,200 m and more) the predominant current is northward between 50 and 60% of the time (Carsey et al. 2016). The analysis of Soloviev et al. (2017) which occurs over a much longer time frame shows that there is a seasonality to the predominance of the current direction with the months observed in Carsey et al. (2016) occurring when a southerly direction is traditionally more predominant. The Soloviev et al. (2017) dataset shows that a northward direction is predominant, but a southward current does frequently occur. Stamates et al. (2013) estimated the percentage of southern flow between 40 – 50 % of the time for nearshore stations. Carsey et al. (2015) concluded that the current flowed north between 66 and 75% of the time at offshore stations and 50 to 60% closer to shore. Considering these reports and data and the fact that the channel runs approximately 2,500 m offshore, an assumption was made that the flow and therefore the sediment distribution will be split 60% to the north and 40% to the south.

To determine the quantity of sediment from the inner port which moves offshore and can therefore settle onto nearby resources, Stamates et al. (2013) and previously modeling studies were consulted. In Stamates et al. (2013) the dilution of substances after exiting the channel and entering the coastal ocean was examined. The relative concentrations of ambient suspended sediments were examined along an east‐west line from just inside the jetties (Main Turning Basin) to near the seaward terminus of the Outer Entrance Channel. These transects show that in general the normalized concentration is reduced to between 20 and 40% of the initial concentration at the seaward end of the channel. The flaw with these measurements are that they are the ambient TSS, so while some of the signal is from the ebb flow through the inlet, there is also part of the signal due to natural processes outside the inlet. Zyserman and Shen (2012) examined the tidal hydraulics related to the Port Everglades Sand Bypass project. There model results suggest that the tidal flow through the inlet tends to be sheared either north or south approximately 1,000 m outside the inlet. To be conservative, this estimate assumes three offshore segments with representative percentages of sediment. In the first 1,000 m offshore 70% of the fines from

Port Everglades, Florida Project December 2020 I‐11 Appendix I Sediment Spillage the MTB and the Widener are expected to contribute to the overall spill and 35% of the fines from the SAC and the TN. In the second 1,000 m these percentages are reduced to 35% and 10%. Finally in the final segment which goes from 2,000 m to approximately 2,600 m to the north and 2,000 m to approximately 2,775 m to the south (to extent of benthic habitat maps) 10% of the fines from the MTB and Widener are accounted for and 0% from the SAC and TN. Within each of the segments the sediment is assumed to be placed uniformly in the cross‐shore direction. Note that the sums for the MTB and Widener exceed 100%. That is because the model treats each segment separately and the values are chosen conservatively to account for the variability in the offshore flow and shear of the tidal flow.

I.5.3 Release Depths and Settling Distances

The particles were assumed to be released at defined depths (3.0 m, 4.6 m, 6.0 m, 7.6 m, (all for overflow) and 13.7 m (at the draghead)). While settling, horizontal currents from the NSU dataset (high, average, and slow) move the particle laterally with the appropriate current bin for the particles vertical location. An average water depth of 15.2 m was assumed to represent the surrounding area. The sediment is likely to be released either near the bed via cutterhead (13.7 m), at the draft of a scow via overflow with an environmental valve which discharges below the barge (3.0 to 7.6 m) or throughout the water column via mechanical excavation with a bias towards 13.7 and 3.0 m water depth. Overflow is the largest source and this analysis looked at various depths between the surface (taken as 3.0 m due to blanking of the ADCP data) and 7.6 m water depth. The distance a particle will travel is sensitive to release depth. Moving the depth up in the water column can dramatically change the distance a particle may travel as shown in Table I‐3. The distances presented in Table I‐3 are the maximum settling distance for the various current profiles, fall velocities and release depths. It should be noted that the total distances presented in these curves are not equal to impacts, rather they set the limits of the distribution of sediments and potential exposure. As shown below in Figure I‐6 the tails of these distributions are very long and given the sediment quantities to be released that sediment thickness at these far distances is negligible.

Port Everglades, Florida Project December 2020 I‐12 Appendix I Sediment Spillage

Figure I‐6. Normalized Suspended sediment concentration versus distance for a sediment release at 20 ft water depth.

Table I‐3. Distance clay particles may travels before reaching a depth of 15 m for various release depths, fall velocities and current speeds.

Current Speed: High High Average Average Low Low

Fall Velocity (m/s): 0.0002 0.001 0.0002 0.001 0.0002 0.001

Release Depth (m) Distance from source (m)

3.0 9454 3212 6974 2016 2454 518

4.6 8300 2560 5691 1676 1938 418

6.0 7222 1933 4783 1387 1658 351

7.6 5818 1444 4003 1105 751 231

13.7 310 53 256 45 47 6

Port Everglades, Florida Project December 2020 I‐13 Appendix I Sediment Spillage

I.5.4 Exponential Distributions and Dilution for Mechanical Dredging

The above curves were developed based on observations of overflow and cutterhead dredges. Similar observations were taken for mechanical dredging and are reported in Collins (1995). Observations of open bucket mechanical dredging in the St. Johns River and the Duwamish Waterway were reported. While these are riverine, the distributions are likely conservative as they are subject to channelized flow and higher current speeds. The same process as was done above, was carried out and the normalized distributions of suspended sediment concentration versus distance were produced. An example of these are shown in Figure I‐7. For the following analysis, the same twelve variations of the curves were analyzed (two curves, twenty‐four total).

All assumptions presented for the model are summarized in below.

Figure I‐7. Normalized suspended sediment concentration versus distance for mechanical dredging.

I.6 Sediment Thickness Exposure

Estimates of the thickness of sediment deposition north and south of the dredge due to dredging during the PEDP were developed based on the assumptions and methods discussed above for four scenarios. 1) A cutter suction dredge with overflow allowed 2) A cutter suction dredge without overflow, with barge decant 3) A cutter suction dredge with direct pipe to a deep water placement area 4) A mechanical dredge without overflow, with barge decant

Port Everglades, Florida Project December 2020 I‐14 Appendix I Sediment Spillage

The results of the expected sedimentation for each of these analyses is detailed below. These areas represent the areal extent to various defined thickness values that the benthos will be exposed to base on the analysis described above. Since there is no time component to this analysis, all the material that is expected to be liberated over the length of the project is introduced at once. In this way the thicknesses presented represent the expected maximum exposure during the project. Additionally, the areas of expected and possible sedimentation were overlain on the combined IWG Benthic Habitat Map and Walker and Klug (2014). Walker and Klug (2014) was used to supplement the IWG map in areas were the IWG map did not have coverage. The acreage of sedimentation for the various habitat types are also presented below.

I.6.1 Scenario 1

For Scenario 1 a total of 337,000 cy of fine‐grained sediment throughout Port Everglades is estimated to be spilled during the multi‐year project (137,000 cy at cutterhead and 200,000 cy through overflow). This is determined based on the fines quantities in Table I‐1 and the spill percentages in Table I‐2. Of that quantity, with the assumptions of material from the inner harbor for the various offshore segments, approximately 120,400 cy will be distributed across the coastal waters from the inlet to approximately 2,700 m offshore. These assumptions for the amount of material that reaches the offshore for this and other scenarios assumes that the remainder of the material that is spilled is deposited within the inner harbor, north or south of the port, or within the direct impact footprint. Of the material to reach seaward of the inlet, 60% of this material (73,300 cy) was assumed to be distributed to the north and 40% was distributed to the south (47,200 cy). For simplicity with the remaining calculations in this and the following sections, the quantities will be converted to cubic meters (56,000 m3 to the north and 36,100 m3 to the south). To the north this volume was evenly distributed over the three segments spanning 2,600 m (32.3 m3/m in Segment 1, 17.7 m3/m in Segment 2 and 10.0 m3/m in Segment 3). To the south it was evenly distributed over 2,775 m (20.2 m3/m in Segment 1, 11.0 m3/m in Segment 2 and 6.2 m3/m in Segment 3). The densities per unit length (area) were then scaled to the sixty combinations of distributions previously discussed. This was done by determining the area under the curve of the distribution and scaling the area (volume per unit length) of the available sediment to the shape of the distribution. This results in a sedimentation depth per distance from the source. Note that any time component is removed from this analysis as all the sediment is released at once. In this analysis all of the available sediment is uniformly distributed in the cross shore and follows the distributions described above. For this scenario various release depths of the overflow were examined between 3.0 and 7.6 m. The spill direct from the cutterhead was assumed at 13.7 m.

The distance to each pre‐defined thickness value for Scenario 1 are shown in Table I‐4 for all overflow depths and Figure I‐8 for the surface release (largest exposure). Two values are presented in the table, a minimum and maximum distance. These represent the expected range of deposition for a given thickness based on all sixty combinations of parameters. In general, the higher the release depth the greater the exposure coverage. Similarly, due to the cross‐shore assumptions and the greater likelihood of sediments from the inner harbor reaching the first 1,000 m or so the distances in segment 1 are the greatest and they decrease in the offshore segments. The lower the release, the distance decreases, but in general the exposure is thicker closer to the source until you get into the tails of the distributions which are the sub‐ centimeter deposition levels. For Table I‐6 only the maximum distance is plotted for each pre‐defined value. Additional tables with additional statistics are provided as an addendum to this report.

Port Everglades, Florida Project December 2020 I‐15 Appendix I Sediment Spillage

The acreage of the benthos exposed to sedimentation based on the characterization by the combined IWG and Walker and Klug (2014) habitat map was also determined. Those values are shown in Table I‐5 below for a CSD with overflow being released at 3.0 m water depth.

Figure I‐8. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 1: a CSD with overflow at 3.0 m water depth.

Table I‐4. Distance north and south of the channel of sedimentation thickness under scenario 1: a CSD with overflow of various quantities at various overflow release depths for segments 1 (A), 2 (B), and 3 (C). (A) – Segment 1 Distance to North from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) Overflow Release Depth (m) (CSD assumed at 13.7 m) 3.0 m 4.6 m 6.0 m 7.6 m Min Max Min Max Min Max Min Max

‐ 50 3 11 4 13 4 13 4 13

25 12 26 9 28 9 26 8 31 Thick

10 22 70 18 69 16 67 14 67 ness (cm) 5 33 132 30 128 28 122 18 113

Sediment 1 74 405 62 475 55 494 30 497

Port Everglades, Florida Project December 2020 I‐16 Appendix I Sediment Spillage

0.5 106 998 71 967 63 959 34 846 0.1 141 2375 92 2403 80 1933 44 1444 Distance to South from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) Overflow Release Depth (m) (CSD assumed at 13.7 m) 3.0 m 4.6 m 6.0 m 7.6 m Min Max Min Max Min Max Min Max 50 2 6 2 8 2 9 3 9 25 6 15 7 16 7 16 5 16

10 17 46 13 47 12 41 11 46 Thickness 5 25 84 21 84 18 84 15 82 (cm) 1 48 254 51 235 47 222 28 297 0.5 88 595 65 626 58 634 31 609 Sediment 0.1 131 1972 86 1983 75 1746 41 1419

(B) – Segment 2 Distance to North from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) Overflow Release Depth (m) (CSD assumed at 13.7 m) 3.0 m 4.6 m 6.0 m 7.6 m Min Max Min Max Min Max Min Max 50 1 5 2 7 2 8 2 8 25 4 12 5 14 6 14 5 14

10 15 38 12 40 11 36 10 41 Thickness 5 24 73 19 72 17 70 14 70 (cm) 1 48 235 47 218 43 202 27 250 0.5 77 440 63 503 56 518 30 518 Sediment 0.1 127 1817 83 1821 73 1621 40 1328 Distance to South from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) Overflow Release Depth (m) (CSD assumed at 13.7 m) 3.0 m 4.6 m 6.0 m 7.6 m Min Max Min Max Min Max Min Max 50 1 4 1 5 1 5 1 5 25 2 6 2 9 3 9 3 10

10 10 21 8 21 8 21 7 25 Thickness 5 18 48 14 49 12 44 11 48 (cm) 1 46 184 40 174 36 163 23 145 0.5 54 259 52 240 48 246 28 308 Sediment 0.1 117 1414 77 1402 68 1296 37 1091

Port Everglades, Florida Project December 2020 I‐17 Appendix I Sediment Spillage

(C) – Segment 3 Distance to North from Source to thickness (m) ‐ Segment 3 (2,000 + m) Overflow Release Depth (m) (CSD assumed at 13.7 m) 3.0 m 4.6 m 6.0 m 7.6 m Min Max Min Max Min Max Min Max 50 1 3 1 4 1 5 1 5 25 2 6 2 8 2 9 3 9

10 10 17 10 17 11 18 10 20 Thickness 5 17 40 18 42 17 38 15 42 (cm) 1 47 164 43 156 41 147 23 133 0.5 64 238 55 222 48 205 27 182 Sediment 0.1 113 985 75 965 66 963 36 837 Distance to South from Source to thickness (m) ‐ Segment 3 (2,000 + m) Overflow Release Depth (m) (CSD assumed at 13.7 m) 3.0 m 4.6 m 6.0 m 7.6 m Min Max Min Max Min Max Min Max 50 1 2 1 2 1 2 1 3 25 1 4 1 4 1 6 1 6

10 1 9 3 9 4 11 5 12 Thickness 5 3 21 9 22 9 22 8 27 (cm) 1 37 113 29 113 29 112 21 108 0.5 51 188 40 188 40 177 24 165 Sediment 0.1 102 588 85 844 61 822 34 835

Port Everglades, Florida Project December 2020 I‐18 Appendix I Sediment Spillage

Table I‐5. Estimates of Exposure acreage for each benthos category for a given pre‐defined value of sedimentation exposure for SCENARIO 1: a CSD with overflow at 3.0 m water depth. Scenario 1 Segment 1 Segment 2 Segment 3 5 1 0.5 0.1 10 5 1 0.5 0.1 10 5 1 0.5 0.1 10 cm Habitat Type cm cm cm cm cm cm cm cm cm cm cm cm cm cm Acropora cervicornis 0.11 0.10 Aggregated Patch Reef 0.22 6.66 0.70 5.14 3.95 27.83 Artificial 2.69 8.66 59.79 0.23 0.42 1.67 17.11 0.57 Colonized Pavement Continuous Seagrass Discontinuous Seagrass Inlet Channel 13.34 0.01 1.24 0.43 Inner Reef 1.70 2.71 9.37 28.78 76.23 0.46 0.85 5.98 3.82 97.90 Middle Reef 3.28 2.92 15.75 10.95 106.21

Nearshore Ridge Com‐ 8.45 10.99 28.17 145.96 450.07 0.67 0.42 20.02 plex Outer Reef 0.20 0.31 1.77 1.05 26.55 4.75 1.93 11.55 7.60 45.40 Patch Reef Ridge 8.78 1.24 6.84 4.06 29.02 Sand 2.42 1.61 7.49 43.98 127.92 8.18 9.77 44.11 34.35 368.42 3.51 0.61 4.59 4.23 58.13 Sand Borrow Area

Scattered Rock in Uncon‐ 1.31 1.73 2.70 1.23 1.03 3.72 1.49 6.26 0.00 solidated Sediment

Port Everglades, Florida Project December 2020 I‐19 Appendix I Sediment Spillage

I.6.2 Scenario 2

For Scenario 2 a total of 150,300 cy of fine‐grained sediment throughout Port Everglades is estimated to be spilled during the multi‐year project (137,000 cy at the cutterhead and 13,300 cy through the decant process). This reduction compared to Scenario 1 is due to the elimination of overflow in the process, but does account for a small contribution through one‐time barge decanting prior to transit to the ODMDS. Of this quantity 57,900 cy is expected to reach the resources with the rest settling out in the inner harbor, north or south of the port and within the direct impact area of the channel. This is split between 35,200 cy (26,900 m3) to the north and 22,700 cy (17,400 m3) to the south (based on the 60% north /40% south assumption introduced previously). To the north this volume was evenly distributed over the three segments spanning 2,600 m (15.0 m3/m in Segment 1, 8.7 m3/m in Segment 2 and 5.3 m3/m in Segment 3). To the south it was evenly distributed over 2,775 m (9.4 m3/m in Segment 1, 5.4 m3/m in Segment 2 and 3.3 m3/m in Segment 3).

It is seen in Table I‐6 and Figure I‐9 that the distances away from the channel to the various sedimentation thickness pre‐defined values are dramatically reduced compared to Scenario 1. In this scenario nearly all of the sediment is being released near the bed with only a minimal amount coming from decanting near the surface. Based on the fall velocity of the material it is not expected for any sediment to reach beyond approximately 310 m due strictly to the action of the cutterhead in liberating the fines (bedload sediment transport / resuspension neglected). The profiles were stretched slightly beyond that based on engineering judgment related to other dredging projects. This allowed for a more even distribution of the lower (0.5 and 0.1 cm) values rather than having them all stack up at 310 m. Sedimentation thickness at distances beyond approximately 310 m are very small. Acreage exposure of affected benthos is presented in Table I‐7.

Port Everglades, Florida Project December 2020 I‐20 Appendix I Sediment Spillage

Figure I‐9. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 2: a CSD with barge decanting at 3.0 m water depth.

Table I‐6. Distance north and south of the channel of sedimentation thickness under scenario 2: a CSD with barge decanting at 3.0 m water depth for segments 1 (A), 2 (B), and 3 (C). (A) – Segment 1 Segment 1 (0 ‐ 1,000 m) Distance to North from Source to thick‐ ness (m) Decant at Sur‐ face Min Max 50 1 7 25 1 9 10 4 16 Thickness 5 7 58 (cm) 1 17 228 0.5 21 306 Sediment 0.1 83 475

Port Everglades, Florida Project December 2020 I‐21 Appendix I Sediment Spillage

Distance to South from Source to thick‐ ness (m) Decant at Sur‐ face Min Max 50 1 5 25 1 8 10 2 11 Thickness 5 5 21 (cm) 1 14 176 0.5 18 253 Sediment 0.1 43 381

(B) – Segment 2 Segment 2 (1,000 ‐ 2,000 m) Distance to North from Source to thick‐ ness (m) Decant at Sur‐ face Min Max 50 1 5 25 1 7 10 3 11 Thickness 5 6 19 (cm) 1 13 169 0.5 17 245 Sediment 0.1 28 369 Distance to South from Source to thick‐ ness (m) Decant at Sur‐ face Min Max 50 1 3 25 1 6 10 1 9 Thickness 5 3 12 (cm) 1 11 118 0.5 15 193 Sediment 0.1 24 287

Port Everglades, Florida Project December 2020 I‐22 Appendix I Sediment Spillage

(C) Segment 3 Segment 3 (2,000 + m) Distance to North from Source to thick‐ ness (m) Decant at Sur‐ face Min Max 50 1 3 25 1 6 10 2 9 Thickness 5 4 17 (cm) 1 13 168 0.5 16 244 Sediment 0.1 24 367 Distance to South from Source to thick‐ ness (m) Decant at Sur‐ face Min Max 50 1 2 25 1 4 10 1 7 Thickness 5 2 10 (cm) 1 11 117 0.5 14 192 Sediment 0.1 22 284

Port Everglades, Florida Project December 2020 I‐23 Appendix I Sediment Spillage

Table I‐7. Estimates of Exposure acreage for each benthos category for a given pre‐defined value of sedimentation exposure for Scenario 2: a CSD with barge decanting at 3.0 m water depth. Scenario 2 Segment 1 Segment 2 Segment 3 10 5 1 0.5 0.1 10 5 1 0.5 0.1 10 5 1 0.5 0.1 Habitat Type cm cm cm cm cm cm cm cm cm cm cm cm cm cm cm Acropora cervicornis Aggregated Patch Reef 6.46 0.22 6.02 3.97 5.59 Artificial 0.00 1.63 33.05 18.96 17.73 0.02 2.49 15.17 Colonized Pavement Continuous Seagrass Discontinuous Seagrass Inlet Channel 6.15 4.00 3.20 0.64 0.17 0.86 Inner Reef 0.11 0.90 8.11 4.61 9.27 0.08 0.11 4.41 3.10 2.83 Middle Reef 1.14 0.66 13.56 7.21 7.00

0.02 4.75 29.56 10.68 34.69 0.01 0.71 0.50 Nearshore Ridge Complex Outer Reef 0.08 0.03 1.20 1.12 1.29 4.19 0.61 13.84 7.73 10.78 Patch Reef Ridge 8.45 0.37 8.26 4.11 5.42 Sand 0.39 1.55 4.59 1.97 8.13 2.60 1.54 38.89 21.60 24.87 3.33 0.20 5.40 4.33 7.26 Sand Borrow Area

Scattered Rock in Unconsoli‐ 0.07 1.21 1.24 0.40 0.20 4.31 1.09 2.20 0.00 dated Sediment

Port Everglades, Florida Project December 2020 I‐24 Appendix I Sediment Spillage

I.6.3 Scenario 3

The values in Scenario 3 are very similar to Scenario 2 with the only change being that decanting is not included as direct pump to an offshore disposal area is assumed. This results in a total of 137,000 cy of fine‐grained sediment to be spilled at the cutterhead during the multi‐year project. Of this quantity 53,400 cy is expected to reach the resources with the rest settling out in the inner harbor, north or south of the port and within the direct impact area of the channel. This is split between 32,500 cy (24,800 m3) to the north and 21,000 cy (16,000 m3) to the south. To the north this volume was evenly distributed over the three segments spanning 2,600 m (13.8 m3/m in Segment 1, 8.1 m3/m in Segment 2 and 5.0 m3/m in Segment 3). To the south it was evenly distributed over 2,775 m (8.6 m3/m in Segment 1, 5.0 m3/m in Segment 2 and 3.1 m3/m in Segment 3).

The results (Table I‐8 and Figure I‐10) are essentially the same as Scenario 2 with most of the spill to a thickness of 0.5 cm confined within 300 m of the channel. As before the based on the assumptions in the model the distances away from the channel to thickness values decrease further offshore based on less material from the inner harbor reaching that far offshore. Similarly, the estimates of exposure acreage in Table I‐9 are similar to those in Scenario 2

Figure I‐10. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 3: a CSD with direct pump to offshore disposal.

Port Everglades, Florida Project December 2020 I‐25 Appendix I Sediment Spillage

Table I‐8. Distance north and south of the channel of sedimentation thickness under scenario 3: a CSD with direct pump to offshore disposal for segments 1 (A), 2 (B), and 3 (C). (A) – Segment 1 Segment 1 Distance to North from Source to thick‐ ness (m) Direct Pump

Min Max

50 1 7 25 1 12

10 2 18 Thickness 5 4 56 (cm) 1 7 225 0.5 13 300

Sediment 0.1 23 465 Distance to South from Source to thick‐ ness (m) Direct Pump

Min Max

50 1 6 25 1 12

10 2 18 Thickness 5 3 24 (cm) 1 6 174 0.5 10 249 Sediment 0.1 14 376

(B) Segment 2 Segment 2 Distance to North from Source to thick‐ ness (m) Direct Pump

Min Max

50 1 6 25 1 12

10 1 18 Thickness 5 3 24 (cm) 1 6 167 0.5 10 242

Sediment 0.1 16 364

Port Everglades, Florida Project December 2020 I‐26 Appendix I Sediment Spillage

Distance to South from Source to thick‐ ness (m) Direct Pump

Min Max

50 1 6 25 1 12

10 1 18 Thickness 5 2 24 (cm) 1 5 116 0.5 8 191 Sediment 0.1 13 310

(C) ‐ Segment 3 Segment 3 Distance to North from Source to thick‐ ness (m) Direct Pump

Min Max

50 1 6 25 1 12

10 1 18 Thickness 5 2 24 (cm) 1 5 115 0.5 8 190 Sediment 0.1 12 310 Distance to South from Source to thick‐ ness (m) Direct Pump

Min Max

50 1 6 25 1 12

10 1 18 Thickness 5 1 24 (cm) 1 4 66 0.5 5 139 Sediment 0.1 8 256

Port Everglades, Florida Project December 2020 I‐27 Appendix I Sediment Spillage

Table I‐9. Estimates of Exposure acreage for each benthos category for a given pre‐defined values of sedimentation exposure for Scenario 3: a CSD with direct pump to offshore disposal. Scenario 3 Segment 1 Segment 2 Segment 3 10 5 1 0.5 0.1 10 5 1 0.5 0.1 10 5 1 0.5 0.1 Habitat Type cm cm cm cm cm cm cm cm cm cm cm cm cm cm cm Acropora cervicornis Aggregated Patch Reef 6.89 0.25 2.99 3.79 6.04 Artificial 0.00 1.46 32.39 18.42 19.09 0.01 2.20 15.07 Colonized Pavement Continuous Seagrass Discontinuous Seagrass Inlet Channel 8.24 2.64 2.47 1.10 0.25 0.32 Inner Reef 0.15 0.81 8.02 4.57 8.92 0.18 0.08 4.26 3.08 3.35 Middle Reef 2.08 0.66 12.40 7.27 7.45

0.04 4.52 29.60 10.18 32.87 0.01 0.70 0.53 Nearshore Ridge Complex Outer Reef 0.17 0.06 1.05 1.12 1.65 5.26 0.65 7.26 7.69 12.10 Patch Reef Ridge 9.16 0.43 4.31 4.37 6.28 Sand 0.47 1.42 4.60 1.96 7.68 4.63 1.60 36.23 21.53 29.02 3.64 0.19 2.64 3.68 7.24 Sand Borrow Area

Scattered Rock in Unconsolidated 0.06 1.09 1.36 0.74 0.31 3.80 1.16 2.48 0.00 Sediment

Port Everglades, Florida Project December 2020 I‐28 Appendix I Sediment Spillage

I.6.4 Scenario 4

The values in Scenario 4 are for mechanical dredging and use the combinations of distributions based on those in Figure I‐7 as opposed to the above scenarios. The spill rate for mechanical dredging is relatively small (5%) and is combined with the small rate for decanting (0.1%). As a result the total spill volume is only 74,900 cy. Of that quantity 25,500 cy is expected to reach the resources with the rest settling out in the inner harbor, north or south of the port and within the direct impact area of the channel. This is split between 15,500 cy (11,900 m3) to the north and 10,000 cy (7,600 m3) to the south. To the north this volume was evenly distributed over the three segments spanning 2,600 m (7.0 m3/m in Segment 1, 3.7 m3/m in Segment 2 and 1.9 m3/m in Segment 3). To the south it was evenly distributed over 2,775 m (4.4 m3/m in Segment 1, 2.3 m3/m in Segment 2 and 1.2 m3/m in Segment 3). While in reality spill occurs throughout the up cycle in mechanical dredging, there is a bias to spill at the bottom and at the surface. To account for this bias it was assumed that 40% of the spill occurs near the bed, 20% at mid‐depth, and the remaining 40% near the surface. These assumptions combined with the very long tailed distributions of mechanical dredging (derived from riverine observations) result in the majority of the spill be confined within 200 m of the source, but thicknesses of up to 0.1 cm extending to over 1 km north and south of the channel as seen in Table I‐10 and Figure I‐11. Based on the high spillage values used (5%) these values are considered very conservative. The acreage estimates of exposure is presented in Table I‐11.

Figure I‐11. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 4: mechanical dredge with barge decant.

Port Everglades, Florida Project December 2020 I‐29 Appendix I Sediment Spillage

Table I‐10. Distance north and south of the channel of sedimentation thickness under scenario 4: mechanical dredge with barge decant for segments 1 (A), 2 (B), and 3 (C). (A) – Segment 1 Segment 1 Distance to North from Source to thick‐ ness (m) Mechanical Released through Wa‐ ter Column Min Max 50 0 4 25 0 4

10 1 14 Thickness 5 14 27 (cm) 1 46 124 0.5 108 305 Sediment 0.1 697 1218 Distance to South from Source to thick‐ ness (m) Mechanical Released through Wa‐ ter Column Min Max 50 0 4 25 0 4

10 0 5 Thickness 5 5 17 (cm) 1 42 68 0.5 46 172 Sediment 0.1 413 1071

(B) Segment 2 Segment 2 Distance to North from Source to thick‐ ness (m)

Port Everglades, Florida Project December 2020 I‐30 Appendix I Sediment Spillage

Mechanical Released through Wa‐ ter Column Min Max 50 0 4 25 0 4

10 0 4 Thickness 5 2 15 (cm) 1 37 56 0.5 46 136 Sediment 0.1 347 922 Distance to South from Source to thick‐ ness (m) Mechanical Released through Wa‐ ter Column Min Max 50 0 4 25 0 4

10 0 4 Thickness 5 0 6 (cm) 1 23 42 0.5 43 72 Sediment 0.1 230 518

(C) Segment 3 Segment 3 Distance to North from Source to thick‐ ness (m) Mechanical Released through Wa‐ ter Column Min Max

50 0 4 25 0 4

(cm) 10 0 4 Sediment Thickness 5 0 5

Port Everglades, Florida Project December 2020 I‐31 Appendix I Sediment Spillage

1 20 36 0.5 39 60 0.1 201 438 Distance to South from Source to thick‐ ness (m) Mechanical Released through Wa‐ ter Column Min Max 50 0 4 25 0 4

10 0 4 Thickness 5 0 4 (cm) 1 11 23 0.5 24 43 Sediment 0.1 46 244

Port Everglades, Florida Project December 2020 I‐32 Appendix I Sediment Spillage

Table I‐11. Estimates of Exposure acreage for each benthos category for a given pre‐defined value of sedimentation exposure for Scenario 4: mechanical dredge with barge decant. Scenario 4 Segment 1 Segment 2 Segment 3 10 5 1 0.5 0.1 10 5 1 0.5 0.1 10 5 1 0.5 0.1 Habitat Type cm cm cm cm cm cm cm cm cm cm cm cm cm cm cm Acropora cervicornis 0.11 Aggregated Patch Reef 6.29 0.11 1.02 0.94 14.74 Artificial 0.12 9.40 41.80 20.05 18.80 Colonized Pavement Continuous Seagrass Discontinuous Seagrass Inlet Channel 4.31 4.81 4.23 0.32 0.15 1.21 Inner Reef 0.07 0.27 3.35 5.26 63.31 0.00 0.13 0.72 2.30 35.84 Middle Reef 0.42 0.81 3.95 5.69 53.97

0.00 0.46 15.86 17.69 274.30 4.07 Nearshore Ridge Complex Outer Reef 0.04 0.02 0.39 0.36 7.00 3.75 0.26 2.74 2.36 29.95 Patch Reef Ridge 8.18 0.19 1.75 1.57 15.47 Sand 0.31 0.51 3.01 3.57 71.48 1.00 1.90 11.19 17.40 176.36 3.19 0.07 0.85 0.76 18.30 Sand Borrow Area

Scattered Rock in Unconsoli‐ 0.04 5.55 0.20 0.20 1.57 1.44 8.38 0.00 dated Sediment

Port Everglades, Florida Project December 2020 I‐33 Appendix I Sediment Spillage

I.6.5 Direct Impacts

For all the scenarios direct impacts are assumed within the channel footprint. These values were calculated within the new channel framework out to the 57 ft contour and are presented in Table I‐12 below (absent of any slope impacts).

Table I‐12. Direct Impacts in the Navigation Channel (not including side slope impacts). Direct Impacts Direct Impacts Habitat Type Acreage Acropora cervicornis Aggregated Patch Reef Artificial Colonized Pavement Continuous Seagrass Discontinuous Seagrass Inlet Channel 55.19 Inner Reef Middle Reef 6.71 Nearshore Ridge Com‐

plex Outer Reef 10.95 Patch Reef Ridge Sand 25.87 Sand Borrow Area

Scattered Rock in Un‐ 2.68 consolidated Sediment

I.7 Summary

This analysis used available literature and data to estimate the expected areas of sedimentation exposure from the Port Everglades Deepening Project. The total quantity of dredged material was estimated and from the available geotechnical data the expected quantity of fine grained material was determined. Based on the literature, estimates of spillage for the various dredging methodologies considered were used to determine the quantity of fines that could be spilled during the project. From there, assumptions were made regarding the quantity of material from the inner port that reaches the offshore area, the distance offshore that inner harbor sediment will travel, and assumptions of the percentage of the time the offshore flow is north or south directed. These assumptions were based on available literature, model results, and engineering judgment and are summarized in Table I‐13. They resulted in a total quantity of

Port Everglades, Florida Project December 2020 I‐34 Appendix I Sediment Spillage fines that is expected to be spilled and distributed both north and south of the offshore channel which are summarized in Table I‐13 and Table I‐14. Depending on the type of equipment to be used in the scenario, representative concentration versus distance curves were developed based on observations in the literature of suspended sediment concentration and adjustments for dilution of the measurements. Finally the available sediment and maximum expected excursion distance based on local currents and the sediment fall velocity was scaled to the distribution and the distance where the sediment thickness reaches pre‐defined values was determined.

This values in this analysis are expected to be conservative given that the time component is not accounted for. In reality over the multi‐year project length energetic events will occur which disrupt the sediment, resuspend it and further winnow and distribute it. What is presented here assumes that all the material is deposited at once. Different fall velocities and horizontal current fields were analyzed to attempt to conservatively bookend expected conditions. While sediment thickness values are presented, they are likely better called thickness exposure values due to the lack of a time component (i.e. at this distance out there is the potential to be exposed to sedimentation up to this amount during the dredging process).

The four scenarios showed that overflow is the largest culprit when it comes to potential sedimentation. This can somewhat be mitigated by requiring overflow to be released as deep in the water column as possible. Not allowing overflow can be costly, but results in a large reduction in the expected area of sedimentation exposure. An enhanced blasting plan coupled with a mechanical dredge will likely reduce sedimentation exposure as well, especially those above 0.1 cm.

Additional analyses were conducted subsequent to the development of this report focusing on the coarse grain material. That is provided as an addendum to this report and follows this report. Likewise additional statistical measures of the data presented were developed and are presented in a subsequent addendum.

Table I‐13. Summary of assumptions. Assumption Value Segment Rock Overburden OEC 782,330 274,732 IEC 30,753 276,940 MTB 648,521 347,724 Volume of material to be dredged (cy) Widener 164,469 536,265 SAC 268,050 1,303,450 TN 486,972 121,556 Total 2,381,095 2,860,667 Segment Rock Overburden OEC 18.6% 5.4% IEC 8.0% 3.3% Fines percentage of dredge material MTB 16.0% 36.2% Widener 8.0% 36.2% SAC 16.0% 54.0% TN 10.0% 54.0% Water depth (m) 15.24 Process Depth Spill Depth (m) CSD 13.7

Port Everglades, Florida Project December 2020 I‐35 Appendix I Sediment Spillage

3.0 4.6 Overflow 6.0 7.6 Decant 3.0 3.0 (40%) Mechanical 7.6 (20%) 13.7 (40%) CSD Overflow Decant Mechanical Spill Rate (% of fines) Rock 15 15 1 5 Overburden 7.5 15 0.1 5 Settling Velocity (m/s) 0.0002, 0.001 0.1 Current Velocity (m/s) 0.25 Depth averaged peak velocity initial value 1.0 Direction of offshore flow 60 / 40 % North / % South Segment 1 Segment 2 Segment 3 MTB 70 35 10 Percentage of fines from inner harbor Widener 70 35 10 reaching each segment SAC 35 10 0 TN 35 10 0 Duration of dredging All material spilled at once Cross‐shore distribution Spill distributed uniformly within three segments Decay of concentration from source Exponential curve fit to published data Lateral spreading DREDGE model results

Port Everglades, Florida Project December 2020 I‐36 Appendix I Sediment Spillage

Table I‐14. Summary of scenarios and spill volumes. Scenario 1 Scenario 2 Scenario 3 Scenario 4 Description CSD with overflow CSD with barge decant CSD with direct pump to Mechanical dredge with disposal area barge decant Source CSD Overflow CSD Decant CSD Mechanical Decant Spill Vol‐ Segment 1 29,270 39,430 29,270 2,630 29,270 14,610 280 ume Segment 2 17,120 20,540 17,120 1,370 17,120 7,700 150 (cy) Segment 3 7,040 7,040 7,040 470 7,040 2,700 50 Total 53,430 67,010 53,430 4,470 53,430 25,010 480

Port Everglades, Florida Project December 2020 I‐37 Appendix I Sediment Spillage

I.8 References

Becker, J., van Eekelen, E., van Wiechen, J., de Lange, W., Damsma, T., Smolders, T., and M. van Koningsveld, 2015. Estimating source terms for far field dredge plume modelling. Journal of Environmental Management. 149, 282‐293.

Carsey, T., J. Stamates, J. Bishop, C. Brown, A. Campbell, H. Casanova, C. Featherstone, M. Gidley, M. Kosenko, R. Kotkowski, J. Lopez, C. Sinigalliano, L. Visser, and J.‐Z. Zhang, 2015. Broward County coastal ocean water quality study, 2010‐2012. NOAA Technical Report, OAR‐AOML‐44, 261 pp.

Carsey, T., Stamates, J., Enochs, I., Jones, P., and C. Featherstone, 2016. Water Quality and Reef Monitoring Along the Southeast Coast. Final Report. Atlantic Oceanographic and Meteorological Laboratory National Oceanic and Atmospheric Administration, U.S. Department of Commerce

Collins, M.A., 1995. Dredging‐Induced Near‐Field Resuspended Sediment Concentrations and Source Strengths. USACE ERDC MP D‐95‐2.

Dankers, P.J.T. 2002. The behavior of fines released due to dredging: A literature review. Delft, the Netherlands: Hydraulic Engineering Section, Faculty of Civil Engineering and Geosciences, Delft University.

Foster, T. and J. Van Berkel, 2017. Proactive and Adaptive Measures for the Management of Coastal Development Induced Sediment Plume Impacts. DHI presentation on 27 April 2018, Ft. Lauderdale, FL.

Kemps, H. and R. Masini, 2017. Estimating dredge source terms – a review of contemporary practice in the context of Environmental Impact Assessment in Western Australia. WAMSI Dredging Science Node

Kuo, A. Y., and D. F. Hayes, 1991. A model for turbidity plume induced by bucket dredge. Journal of Waterways, Port, Coastal, and Ocean Engineering 117(6):610‐623. American Society of Civil Engineers

Kuo, A. Y., Welch, C. S., and R. J. Lukens, 1985. Dredge induced turbidity plume model. Journal of Waterways, Port, Coastal, and Ocean Engineering 111(3):476‐495. American Society of Civil Engineers

Mills, D. and H. Kemps, 2016. Generation and release of sediments by hydraulic dredging: a review. WAMSI Dredging Science Node

Nichols, M., Diaz, R.J., and Schaffner, L.C., 1990. Effects of hopper dredging and sediment dispersion, Chesapeake Bay. Environ Geol Water Sci. Vol 15, No. 1, 31 – 43.

Reine, K.J. and Schroeder, P.R. (2015). Characterization of Suspended Sediment Plumes Resulting from Barge Decanting in San Francisco Bay. ERDC/EL TR‐15‐5

Schroeder, P.R, and S. Pranger, 2018. Particle Size Distribution of Port Everglades Outer Entrance Channel Materials and Settling Properties of Sandstone Materials. USACE ERDC.

Port Everglades, Florida Project December 2020 I‐38 Appendix I Sediment Spillage

Schroeder, P., Pranger, S., Wade, R., McComas, B., and J. Smith, 2017. Characterization of Port Everglades Material for Settling and Erosion Properties, USACE ERDC.

Soloviev, A.V., Dean, C.W., Weisberg, R.H., Luther, M.E., and J. Wood, 2015. ADCP Mooring System on the Southeast Florida Shelf. NSU Oceanography Faculty Reports, 12 p. http://nsuworks.nova.edu/occ_facreports/52

Soloviev, A.V., Hirons, A., Maingot, C., Dean, C.W., Dodge, R.E., Yankovsky, A.E., Wood, J. Weisber, R.H., Luther, M.E., and J.P. McCreary, 2017. Southward flow on the western flank of the Florida Current. Deep‐Sea Research Part I (125).

Spearman, J., 2015. A review of the physical impacts of sediment dispersion from aggregate dredging. Marine Pollution Bulletin, Vol. 94, Issues 1 – 2, 260 – 277.

Stamates, S.J., J.R. Bishop, T.P. Carsey, J.F. Craynock, M.L. Jankulak, C.A. Lauter, and M.M. Shoemaker, 2013: Port Everglades flow measurement system. NOAA Technical Report, OAR‐AOML‐42, 22pp.

USACE Dredging and Dredged Material Management Engineer Manual (USACE 2015) United States Army Corps of Engineers – Jacksonville District, Engineering Division, Geosystems Branch (SAJ EN‐G), 2017. MFR – Port Everglades Harbor Deepening (Project No. 452862), Review of PD‐EC Dredging Scenarios. 48 p.

Walker, B. K. and K. Klug, 2014. Southeast Florida Shallow‐Water Habitat Mapping & Coral Reef Community Characterization. Florida DEP Coral Reef Conservation Program Report: 1 ‐71. http://nsuworks.nova.edu/occ_facreports/87.

Winterwerp, J.C. 2002. Near‐field behavior of dredging spill in shallow water. Journal of Waterway, Port, Coastal and Ocean Engineering, 128(2), 96‐98.

Zyserman, J.A., and T. Shen, 2012. Port Everglades, FL Assessment of Dredging Spoils Dispersal and Deposition Final Report. DHI Project No. 41801142. 19 April 2012.

Port Everglades, Florida Project December 2020 I‐39 Appendix I Sediment Spillage

I.9 Addendum 1 ‐ Evaluation of Expected Sedimentation Exposure Offshore of Port Everglades as a Result of the Port Everglades Deepening Project

I.9.1 Introduction

This document is an addendum to the 15 May 2020 report which summarized an analytical estimate of sediment deposition of fine‐grained material resulting from the Port Everglades Deepening Project (PEDP). This addendum presents an estimate of the sediment deposition of coarse‐grained material using the same methodology as the earlier report. Readers are referred to the earlier report for a more detailed description of the means and methods as well as background information and the results of the fine‐ grained material analysis.

I.9.2 Sediment Quantities and Characteristics

The sediment characteristics of the rock and overburden material at Port Everglades were defined in Schroeder (2018) and through analysis of additional geotechnical data by the Geosystems Branch, Engineering Division of United States Army Corps of Engineers (USACE) Jacksonville District (SAJ EN‐G). This analysis was carried out for the various segments of PEDP: the Outer Entrance Channel (OEC), the Inner Entrance Channel (IEC), Main Turning Basin (MTB) / Widener, the Southport Access Channel (SAC), and the Turning Notch (TN). The evaluation focused on the number of fines (silt and/or clay size materials) that may be generated during dredging of rock and overburden sediment present at the project site for the planned project depths. This evaluation consisted of review of ninety two core borings drilled in the project area between 2016 and 2018 (Figure I‐12) as well as historical logs for over two hundred historical borings dating back to the 1950s. In the 15 May 2020 evaluation, the available data was not investigated to determine the development of coarse grain material from the dredging process. For the overburden material the quantity was estimated as all overburden material that was not classified as fine grained previously. For the rock material it was assumed that 50% of all the rock material dredged would be crushed and classified as coarse‐grained sand. When combined with the previous assumptions about the fine‐grained material this would leave between 31.8% and 42% of the rock material being removed as material coarser than sand and is not accounted for in either this or the previous assessment.

Table I‐15 summarizes the estimated percentage and volume of the coarse‐grained material for both rock and overburden sediment within the project segments. The estimated percentage of bedrock volume consisting of coarse‐grained material was estimated at 50% in the absence of additional data. Schroeder (2018) found that the sand size percentages for crushed rock varied between about 33% and 69% although the crushing and milling process undertaken was designed to generate fine material and may underestimate the larger sized material which would result from the dredging process. As a result of this simplifying assumption, the total amount of coarse material that will be generated in the dredging process is estimated at 1,190,548 cy. This is about 3.3 times the volume of fines estimated in the original analysis and considered an extremely conservative estimate in the absence of better data. For the overburden material everything that was not previously accounted for in the estimate for fine grained material was assumed to be coarse grained. This leads to an estimated 1,243,311 cy of sand that will be dredged. This is about 130,000 cy greater than the volume of fines estimated in the fine‐grained analysis.

For this analysis all the particles were assumed to be sand sized particles (d50 = [0.1 to 0.25] mm) with a fall velocity of 0.014 m/s and 0.050 m/s based on Stokes Law for sand sized particles. By using two settling velocities the relationship between areal extent and predicted thickness can be examined. The higher the

Port Everglades, Florida Project December 2020 I‐40 Appendix I Sediment Spillage settling velocity, the predicted areal extent of plume migration and deposition will decrease, but thicknesses will increase.

Figure I‐12. Location of 92 core borings taken at Port Everglades between 2016 and 2018.

Port Everglades, Florida Project December 2020 I‐41 Appendix I Sediment Spillage

Table I‐15. Summary of sediment quantities, percent coarse, and total quantities of coarse material. Bedrock Overburden / Sediment Estimated Calculated Percentage of Rock Re‐ Rock Estimated Rock Calculated Estimated Percent Estimated moval Volume Con‐ Removal Volume con‐ Overburden / of Overburden/Sedi‐ Overburden / Sediment Volume sisting of sisting Sediment ment volume consisting of (cubic Coarse Mate‐ of Coarse Material Volume Consisting of Coarse Coarse Material Location yards) rial (cubic yards) (cubic yards) Material (cubic yards) Outer Entrance Channel (OEC) 782,330 50.0% 391,165 274,732 94.6% 259,896 Inner Entrance Channel (IEC) 30,753 50.0% 15,377 276,940 96.7% 267,801 Widener ‐ Eastward Channel Expansion 648,521 50.0% 324,261 347,724 6.8% 23,645 Main Turning Basin ‐ Total (MTB‐Total) 164,469 50.0% 82,235 536,265 6.8% 36,466 Southport Access Channel Total 268,050 50.0% 134,025 1,303,450 46.0% 599,587 Turning Notch (Total) 486,972 50.0% 243,486 121,556 46.0% 55,916 Total 2,381,095 50.0% 1,190,548 2,860,667 49.5% 1,243,311

Port Everglades, Florida Project December 2020 I‐42 Appendix I Sediment Spillage

I.9.3 Dredge Equipment

It is anticipated that a mechanical clamshell dredge and/or a cutter suction dredge (CSD) will be used for the PEDP. These two types of equipment combined with confined blasting are the only types of dredging equipment capable of removing the rock found in the project area.

For mechanical dredges, sediment plumes are generally released in pulses during the lift phase of the dredging cycle. The plume is discontinuous from intermittent, discrete, very slow‐moving sources. Generally, the spillage is distributed throughout the water column with significant biases toward the surface and near bottom. CSD‐related spillage sources that may contribute to dredge induced suspended sediment plumes are from the scow overflow and the rotating cutterhead. For the cutterhead spillage, the rotation rate, swing speed, cut depth, and sediment properties influence the amount of sediment suspended (J. Becker et al. 2015). The suspended sediment is generated close to the bed and a large portion will stay low in the water column and settle near the dredge (J. Becker et al. 2015). As the cutterhead works, material is entrained into the suction line. The material that is not entrained is referred to as spillage and is broken into two categories: residual and resuspended (Mills and Kemps 2016). The resuspended material is that which contributes to the far field plume and is the focus here (not to be confused with resuspension of material far from the source due to hydrodynamics and sediment transport). The residual material refers to material that is rapidly deposited to the seabed.

I.9.4 Spillage Estimates

Data on the spillage rate as a percentage of the total volume of excavated material varies from project to project, is often not reported or measured, and consensus values do not exist. As noted in Mills and Kemps (2016) relatively little data have been published in relation to sand spillage for CSDs cutting hard rock. As such pertinent literature was reviewed to consolidate published estimates and develop rates for this analysis. Kemps and Masini (2017) provided a summary report on estimates of the primary source term contributions for CSDs and for overflow from trailing suction hopper dredges (TSHD) on several projects in Western Australia. This is the most comprehensive collection of spillage source rate estimates. It consists of several spillage rates that vary based on the geological characteristics of the material and the dredge equipment type. These rates were mined from modeling studies where dredging near sensitive resources was an issue.

Included in the Kemps and Masini (2017) analysis were several projects by the Danish Hydraulic Institute (DHI). DHI maintains a database that represents the average of thousands of measurements. These values were presented by Tom Foster and Josh Van Berkel in the 27 April 2018 Danish Hydraulic Institute (DHI) seminar “Proactive and Adaptive Measures for the Management of Coastal Development Induced Sediment Plume Impacts,” however this information was specific to fines generation and not included in the evaluations in this report.

Spillage rates from decanting, or the process of releasing supernatant water to increase a barge’s effective load is assumed to be zero. The coarse material is not expected to be in suspension during the decanting process and therefore not subject to spill.

Based on the above, the spillage rates depicted in Table I‐16 were used in this analysis. For clamshell dredging (i.e. mechanical dredge) the spillage rate is estimated as 2.5% of the sand dredged based on observations from maintenance dredging projects (personal communication: teleconference with Paul

Port Everglades, Florida Project December 2020 I‐43 Appendix I Sediment Spillage

Schoreder and Don Hayes 18 and 19 February 2020). This is considered a high estimate based on this conversation where Dr. Hayes typically recommends a maximum value of 1% for mechanical dredging. For the previous fines assessment 5% was used and 2.5% was chosen for this analysis to limit large deviation from that assessment while recognizing that less coarse material is subject to spill in the mechanical dredging process. The sediment is generally released during the up phase of the dredge cycle throughout the water column with a bias towards the near surface and near bottom. For this analysis the vertical distribution of the release is assumed to be 40% near the bed, 40% at the surface and 20% at mid‐ depth to reflect the biases at the surface and bed.

For CSD the main sources are at the cutterhead and within the overflow discharge from the scow/barge. The selected values are from various studies presented in Kemps and Masini (2017). For the rock, at the cutterhead the rate is estimated at 15%. This is considered a conservative estimate (based on personal communication: teleconference with Paul Schroeder and Don Hayes, 18 and 19 February 2020 with ERDC, 2020). The rate at the cutterhead for the overburden is estimated as 7.5%. ERDC guidance suggests using 1% as a conservative estimate of spillage at the cutterhead. Therefore, the rates used herein are considered extremely conservative. For overflow the spill rate is reduced from that used for the analysis of the fines since the coarse material is not expected to be in suspension at the same concentration as the fines and subject to overflow. A spill rate of 5% was used for both the rock and overburden material for overflow.

At many of the assumed spill rates the resulting plumes are expected to yield a density flow which typically settles at the source and then slowly disperses. To provide a more conservative estimate, a passive plume which can spread much further is assumed in this analysis.

Table I‐16. Summary of Dredge Spill Information. Mechanical CSD – Cutterhead Barge ‐ Overflow Decant Location Throughout wa‐ 5 ft above the bed Various depths below water surface Near‐Sur‐ ter column (13.7 m depth) (3.0 to 7.6 m depth) face (3.0 m depth) Mech. / CSD Spill Rate – Rock 2.5 15 5 0 / 0 (% of coarse ma‐ terial) Spill Rate – Over‐ 2.5 7.5 5 0 / 0 burden (% of coarse ma‐ terial)

I.9.5 Sediment Deposition Distribution

I.9.5.1 Exponential Distributions and Dilution for CSD and Overflow

Based on observations, the suspended sediment distribution decreases exponentially with distance from the source. The USACE Dredging and Dredged Material Management Engineer Manual (USACE 2015) provides notes and summaries of a number of projects exhibiting this behavior. Among the items listed and discussed in the manual are concentration and distance measurements for a number of projects in

Port Everglades, Florida Project December 2020 I‐44 Appendix I Sediment Spillage

Appendix B. Figure B‐2 of this manual provides curves of suspended sediment concentrations versus distance from the source for projects with overflow, showing a return to background levels within approximately 1,200 m and to zero at 2,600 m. Similar plots for aggregate dredging in Spearman (2015) show an exponential decay and return to background within approximately 1,000 to 2,000 m. Nichols et al. (1990) show a similar decrease in concentration but a return to background levels further from the source at a distance of approximately 5,000 m and to zero around 5,700 m. There is a large difference in the overall extents likely due to the locations of measurements, but in terms of concentrations the observations are similar with most of the concentration confined near the source and only lower values measured at greater distances. These studies were not suspended solids from rock dredging nor were they from new work which would generally have lower resuspension rates (personal communication: teleconference with Paul Schroeder and Don Hayes, 18 and 19 February 2020 with ERDC, 2020). Unfortunately, observations from rock dredging new work were not found in the literature. The result is that these spillage estimates and suspended sediment estimates are believed to represent conservative estimates compared to rock dredging.

For this analysis, the suspended sediment concentrations decay in USACE (2015) and Nichols et al. (1990) were taken for consistency with the fines assessment. The sediment deposition was assumed to follow the distribution of the suspended sediment concentration. It is noted that a more appropriate metric may be the sediment mass as a function of distance. In the absence of those measurements USACE (2015) and Nichols et al. (1990) were both used as presented and they were adjusted to account for dilution of the concentration laterally away from the plume axis. To accomplish the later the DREDGE model (Hayes and Je, 2000) was run under various representative scenarios (current speed and fall velocity) and the spread in the suspended sediment concentration laterally as a function of distance from the source was determined. DREDGE couples resuspension source models from the source with a Gaussian dispersion model (Kuo et al 1985, Kuo and Hayes 1991). An adjustment factor was developed based on the centerline concentration in relation to the total concentration (including lateral dispersion). In this way all the mass (including lateral spread / dilution) is accounted for and included in the centerline number. An example of a dilution factor as a function of distance from the source is shown in Figure I‐13.

The original and adjusted observations were normalized and scaled to the expected furthest distance a particle would travel (based on release depth as discussed below). In this way the shape of the distribution is preserved, and it can be scaled so the area under the curve corresponds to the amount of sediment to be released within the expected distance a sand particle will travel while settling. The curves were fit to a representative exponential curve of the form: f(x) = a exp (b) + c exp (d). USACE (2015) provides a range of concentrations versus distance; the following analyses generates three estimates based on the average value and the high and low values associated with the defined error bars (Est. 1, 2, and 3). Similarly, Nichols (1990) information yielded two estimates to cover the range in their data ‐ one based on the peak concentrations observed of a single cycle and the other based on the average of many peak concentrations versus distance measurements.

Port Everglades, Florida Project December 2020 I‐45 Appendix I Sediment Spillage

14 12 10 Factor

8 6 4 Dilution 2 0 0 2000 4000 6000 8000 10000 12000 Distance from Source (m)

Figure I‐13. Example of a dilution factor used to adjust suspended sediment concentration to account for lateral spreading not depicted in centerline observations.

I.9.5.2 Representative Current Fields and Distributions

The same current fields and percentage of spilled sediment to reach each offshore segment was used as was done for the fines assessment. The currents were obtained from a Nova Southeastern University maintained acoustic Doppler current profiler (ADCP) off Dania Beach in 11 m water depth which measured currents from 25 June 1999 to 03 May 2013 (Soloviev et al. 2015). A maximum, average, and minimum flow period were used in the analysis to ensure that the maximum distance and sedimentation exposure is accounted for. As before the assumed north / south distribution is 60% of material to the north and 40% of material to the south. The same three offshore segments were used as before as well. Based on the faster fall velocities of the coarse sediment (as shown in Table I‐17 and Table I‐18) none of the material from the inner harbor (MTB, Widener, SAC, and TN) is expected to reach out past the jetties and into the open ocean. This varies from the fines assessment where it was assumed that in the first 1,000 m offshore 70% of the fines from the MTB and the Widener are expected to contribute to the overall spill and 35% of the fines from the SAC and the TN. In the second 1,000 m these percentages were reduced to 35% and 10%. Finally, in the final segment which goes from 2,000 m to approximately 2,600 m to the north and 2,000 m to approximately 2,775 m to the south 10% of the fines from the MTB and Widener are accounted for and 0% from the SAC and TN were previously assumed. Within each of the segments the sediment is assumed to be placed uniformly in the cross‐shore direction. Note that the sums for the MTB and Widener exceed 100%. That is because the model treats each segment separately and the values are chosen conservatively to account for the variability in the offshore flow and shear of the tidal flow.

I.9.5.3 Release Depths and Settling Distances

The particles were assumed to be released at defined depths (3.0 m, 4.6 m, 6.0 m, 7.6 m, (all for overflow) and 13.7 m (at the cutterhead)). While settling, horizontal currents from the NSU dataset (high, average, and slow) move the particle laterally with the appropriate current bin for the particles vertical location. An average water depth of 15.2 m was assumed to represent the surrounding area. The sediment is likely to be released either near the bed via cutterhead (13.7 m), at the draft of a scow via overflow with an environmental valve which discharges below the barge (3.0 to 7.6 m) or throughout the water column via mechanical excavation with a bias towards 13.7 and 3.0 m water depth. Overflow is the largest source and this analysis looked at various depths between the surface (taken as 3.0 m due to blanking of the

Port Everglades, Florida Project December 2020 I‐46 Appendix I Sediment Spillage

ADCP data) and 7.6 m water depth. The distance a particle will travel is sensitive to release depth. Moving the depth up in the water column can dramatically change the distance a particle may travel as shown in Table I‐17. The distances presented in Table I‐17 are the maximum settling distance for the various current profiles, fall velocities and release depths. It should be noted that the total distances presented in these curves are not equal to impacts, rather they set the limits of the distribution of sediments and potential exposure. As shown below the tails of these distributions are very long and given the sediment quantities to be released that sediment thickness at these far distances is negligible.

Table I‐17. Distance sand particles may travel before reaching a depth of 15 m for various release depths, fall velocities and current speeds. Current Speed: Average Average High High Low Low Fall Velocity (m/s): 0.05 0.014 0.05 0.014 0.05 0.014 Release Depth (m) Distance from source (m) 3.0 129 379 212 633 53 167 4.6 104 330 170 549 42 144 6.0 104 280 170 465 42 120 7.6 78 256 126 423 31 109 13.7 2 52 2 85 2 21

I.9.5.4 Exponential Distributions and Dilution for Mechanical Dredging

The above curves were developed based on observations of overflow and cutterhead dredges. Similar observations were taken for mechanical dredging and are reported in Collins (1995). Observations of open bucket mechanical dredging in the St. Johns River and the Duwamish Waterway were reported. While these are riverine, the distributions are likely conservative as they are subject to channelized flow and higher current speeds. The same procedure was followed for mechanical dredge spillage estimates and the normalized distributions of suspended sediment concentration versus distance were produced. For the following analysis, the same twelve variations of the curves were analyzed (two curves, twenty‐four total). All assumptions used for the model are summarized in below table.

I.9.5.5 Sediment Thickness Exposure

Estimates of the thickness of sediment deposition north and south of the dredge due to dredging during the PEDP were developed based on the assumptions and methods discussed above for four scenarios. 1) A cutter suction dredge with overflow allowed 2) A cutter suction dredge without overflow, with barge decant 3) A cutter suction dredge with direct pipe to a deep‐water placement area 4) A mechanical dredge without overflow, with barge decant

With the assumption that the decant spill is equal to zero, Scenarios 2 and 3 are the same. The results of the expected sedimentation for each of these analyses is detailed below. These areas represent the areal extent to various defined thickness values that the benthos may be exposed to base on the analysis

Port Everglades, Florida Project December 2020 I‐47 Appendix I Sediment Spillage described above. Since there is no time component to this analysis, all the material that is expected to be liberated over the length of the project is introduced at once. In this way the thicknesses presented represent the expected maximum exposure during the project. Additionally, the areas of expected and possible sedimentation were overlain on the combined IWG Benthic Habitat Map and Walker and Klug (2014). Walker and Klug (2014) was used to supplement the IWG map in areas were the IWG map did not have coverage. The acreage of sedimentation for the various habitat types are also presented below in Table I‐18.

Table I‐18. Summary of assumptions. Assumption Value Segment Rock Overburden OEC 782,330 274,732 IEC 30,753 276,940 MTB 648,521 347,724 Volume of material to be dredged (cy) Widener 164,469 536,265 SAC 268,050 1,303,450 TN 486,972 121,556 Total 2,381,095 2,860,667 Segment Rock Overburden OEC 50.0% 94.6% IEC 50.0% 96.7% Coarse percentage of dredge material MTB 50.0% 6.8% Widener 50.0% 6.8% SAC 50.0% 46.0% TN 50.0% 46.0% Water depth (m) 15.2 Process Depth CSD 13.7 3.0 4.6 Overflow 6.0 Spill Depth (m) 7.6 Decant NA 3.0 (40%) Mechanical 7.6 (20%) 13.7 (40%) CSD Overflow Decant Mechanical Spill Rate (% of fines) Rock 15 5 0 2.5 Overburden 7.5 5 0 2.5 Settling Velocity (m/s) 0.014, 0.05 0.1 Current Velocity (m/s) 0.25 Depth averaged peak velocity initial value 1.0 Direction of offshore flow 60 / 40 % North / % South Segment 1 Segment 2 Segment 3 Percentage of coarse material from inner MTB 0 0 0 harbor reaching each segment Widener 0 0 0 SAC 0 0 0

Port Everglades, Florida Project December 2020 I‐48 Appendix I Sediment Spillage

TN 0 0 0 Duration of dredging All material spilled at once Cross‐shore distribution Spill distributed uniformly within three segments Decay of concentration from source Exponential curve fit to published data Lateral spreading DREDGE model results

I.9.5.6 Scenario 1

For Scenario 1 a total of 337,000 cy of course‐grained sediment throughout Port Everglades is estimated to be spilled during the multi‐year project (237,000 cy at cutterhead and 100,000 cy through overflow). This is determined based on the coarse quantities in Table I‐15 and the spill percentages in Table I‐16. Of that quantity, with the assumptions of material from the inner harbor for the various offshore segments, approximately 142,000 cy will be distributed across the coastal waters from the inlet to approximately 2,700 m offshore. These assumptions for the amount of material that reaches the offshore for this and other scenarios assumes that the remainder of the material that is spilled is deposited within the inner harbor, north or south of the port, or within the direct impact footprint. Of the material to reach seaward of the inlet, 60% of this material (85,000 cy) was assumed to be distributed to the north and 40% was distributed to the south (57,000 cy). As described in the fines assessment this quantity was next converted to cubic meters and assumed to be evenly distributed along each segment producing a volume per unit length which was scaled to the distributions previously discussed. Note that any time component is removed from this analysis as all the sediment is released at once. In this analysis all the available sediment is uniformly distributed in the cross shore and follows the distributions described above. For this scenario various release depths of the overflow were examined between 3.0 and 7.6 m. The most impactful from an aerial extent perspective, a release depth of 3.0 m, is shown in the plots and tables. The spill release depth from the cutterhead was assumed at 13.7 m.

The distance to each pre‐defined thickness value for Scenario 1 are shown in Table I‐19 for the 3.0 m overflow depth along with the minimum, mean, standard deviation and 95% confidence limit value based on all the combinations (fall velocity, distribution, and current speed) analyzed. The results are plotted in Figure I‐14 for the surface release (largest areal exposure). Due to the cross‐shore assumptions and the greater likelihood of sediments from the inner harbor reaching the first 1,000 m the distances in segment 1 are the greatest and they decrease in the offshore segments. The lower the release depth, the distance decreases, but in general the exposure is thicker closer to the source until you get into the tails of the distributions which are the sub‐centimeter deposition levels. The sedimentation areal exposure is less than the fines based on the greater fall velocity and the assumption that the overflow spill percentage will be less for the coarse sediments.

The acreage of the benthos exposed to sedimentation based on the characterization by the combined IWG and Walker and Klug (2014) habitat map was also determined. Those values are shown in Table I‐20 below for a CSD with overflow being released at 3.0 m water depth.

Port Everglades, Florida Project December 2020 I‐49 Appendix I Sediment Spillage

Figure I‐14. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 1: a CSD with overflow at 3.0 m water depth.

Port Everglades, Florida Project December 2020 I‐50 Appendix I Sediment Spillage

Table I‐19. Distance north and south of the channel of sedimentation thickness under scenario 1: a CSD with overflow of various quantities at various overflow release depths for segments 1 (A), 2 (B), and 3 (C). (A) – Segment 1 Distance to North from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) 3.0 m Overflow Release Depth (CSD assumed at 13.7 m) Min Max Mean St. Dev. 95% CL ‐ 10 3 30 10 7 12

Thick 5 3 50 16 12 19

(cm) 1 4 172 48 40 58 0.5 4 263 75 69 93 ness 0.1 5 565 154 151 193 Sediment Distance to South from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) 3.0 m Overflow Release Depth (CSD assumed at 13.7 m)

Min Max Mean St. Dev. 95% CL ‐ 10 3 21 8 5 10

Thick 5 3 38 12 9 15

(cm) 1 4 118 37 29 44

ness 0.5 4 210 60 50 73

Sediment 0.1 5 478 141 129 174 (B) – Segment 2 Distance to North from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) 3.0 m Overflow Release Depth (CSD assumed at 13.7 m) Min Max Mean St. Dev. 95% CL ‐ 10 3 30 10 7 12

Thick 5 3 50 16 12 19

(cm) 1 4 172 48 40 58 0.5 4 263 75 69 93 ness 0.1 5 565 154 151 193 Sediment Distance to South from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) 3.0 m Overflow Release Depth (CSD assumed at 13.7 m)

Min Max Mean St. Dev. 95% CL ‐ 10 3 21 8 5 10

Thick 5 3 38 12 9 15

(cm) 1 4 118 37 29 44

ness 0.5 4 210 60 50 73 0.1 5 478 141 129 174 Sediment (C) – Segment 3 Distance to North from Source to thickness (m) ‐ Segment 3 (2,000 + m) 3.0 m Overflow Release Depth (CSD assumed at 13.7 m) Min Max Mean St. Dev. 95% CL

Port Everglades, Florida Project December 2020 I‐51 Appendix I Sediment Spillage

‐ 10 2 29 8 7 10

Thick 5 2 46 11 11 14

(cm) 1 3 86 25 25 31 0.5 3 98 29 28 37 ness 0.1 3 255 48 49 61 Sediment Distance to South from Source to thickness (m) ‐ Segment 3 (2,000 + m) 3.0 m Overflow Release Depth (CSD assumed at 13.7 m)

Min Max Mean St. Dev. 95% CL ‐ 10 2 20 6 4 7

Thick 5 2 36 9 8 11

(cm) 1 2 79 21 22 27

ness 0.5 2 87 26 26 33 0.1 2 213 42 43 53 Sediment

Port Everglades, Florida Project December 2020 I‐52 Appendix I Sediment Spillage

Table I‐20. Estimates of Exposure acreage for each benthos category for a given pre‐defined value of sedimentation exposure for SCENARIO 1: a CSD with overflow at 3.0 m water depth.

Scenario 1

Segment 1 Segment 2 Segment 3 10 cm 5 cm 10 cm 5 cm 10 cm 5 cm 1 cm 1 cm 0.5 cm 0.1 cm 1 cm 0.5 cm 0.1 cm 0.5 cm 0.1 cm Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ Acreage Acreage Acreage Acreage Acreage Acreage Acreage Acreage Habitat Type age age age age age age age Acropora cervicor‐

nis Aggregated Patch 7.12 0.69 1.87 0.47 7.21 Reef Artificial 0.06 0.81 17.84 25.15 27.33 0.04 4.91 13.83 Colonized Pave‐

ment Continuous

Seagrass Discontinuous

Seagrass Inlet Channel 5.19 3.05 0.15 0.84 0.43 0.00 Inner Reef 0.40 0.56 5.58 4.93 20.37 0.35 0.33 4.02 3.62 14.08 Middle Reef 1.74 1.83 10.87 8.19 20.05

Nearshore Ridge 0.83 3.85 22.03 11.29 72.35 0.02 0.77 0.81 Complex Outer Reef 0.19 0.20 0.91 1.37 4.27 3.22 1.78 4.44 1.07 14.74 Patch Reef Ridge 9.61 1.20 2.89 0.62 7.85 Sand 0.00 0.71 3.15 2.60 14.46 5.49 5.61 31.03 25.33 83.93 3.88 0.55 1.46 0.43 7.78 Sand Borrow Area

Scattered Rock in 0.30 2.34 0.91 0.76 3.13 1.11 4.12 0.00 Unconsolidated Sediment

Port Everglades, Florida Project December 2020 I‐53 Appendix I Sediment Spillage

I.9.5.7 Scenario 2/3

For Scenario 2/3 a total of 237,000 cy of coarse‐grained sediment throughout Port Everglades is estimated to be spilled during the multi‐year project (all at the cutterhead). This reduction compared to Scenario 1 is due to the elimination of overflow in the process. Of this quantity 100,600 cy is expected to reach the resources with the rest settling out in the inner harbor, north or south of the port and within the direct impact area of the channel.

It is seen in Table I‐21 and Figure I‐15 that the distances away from the channel to the various pre‐defined sedimentation thickness values are dramatically reduced compared to Scenario 1. In this scenario all the sediment is released near the bed, so it remains confined near the bed and does not travel far. Based on the fall velocity of the material it is not expected for any sediment to reach much beyond approximately 85 m due strictly to the action of the cutterhead in liberating the coarse material (bedload sediment transport / resuspension neglected). The profiles were stretched slightly beyond that to about 110 m based on engineering judgment related to other dredging projects. This allowed for a more even distribution of the lower (0.5 and 0.1 cm) values rather than having them coincide at 85 m. Sedimentation thickness at distances beyond approximately 85 m are very small. Acreage exposure of affected benthos is presented in Table I‐22.

Table I‐21. Distance north and south of the channel of sedimentation thickness under scenario 2: a CSD with spill at the cutterhead for segments 1 (A), 2 (B), and 3 (C). (A) – Segment 1 Distance to North from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) CSD assumed at 13.7 m Min Max Mean St. Dev. 95% CL ‐ 10 2 25 5 6 6

Thick 5 2 41 8 10 10

(cm) 1 2 85 17 24 23

ness 0.5 2 99 19 26 25

Sediment 0.1 2 107 22 29 30 Distance to South from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) CSD assumed at 13.7 m

Min Max Mean St. Dev. 95% CL ‐ 10 2 15 4 3 5

Thick 5 2 32 6 7 8

(cm) 1 2 74 15 21 20

ness 0.5 2 97 18 26 24

Sediment 0.1 2 107 22 28 29

Port Everglades, Florida Project December 2020 I‐54 Appendix I Sediment Spillage

(B) Segment 2 Distance to North from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) CSD assumed at 13.7 m Min Max Mean St. Dev. 95% CL ‐ 10 2 25 5 6 6

Thick 5 2 41 8 10 10

(cm) 1 2 85 17 24 23

ness 0.5 2 99 19 26 25

Sediment 0.1 2 107 22 29 30 Distance to South from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) CSD assumed at 13.7 m

Min Max Mean St. Dev. 95% CL ‐ 10 2 15 4 3 5

Thick 5 2 32 6 7 8

(cm) 1 2 74 15 21 20

ness 0.5 2 97 18 26 24

Sediment 0.1 2 107 22 28 29 (C) Segment 3 Distance to North from Source to thickness (m) ‐ Segment 3 (2,000 + m) CSD assumed at 13.7 m Min Max Mean St. Dev. 95% CL ‐ 10 2 21 5 5 6

Thick 5 2 37 7 9 9

(cm) 1 2 81 16 23 22

ness 0.5 2 98 18 26 25

Sediment 0.1 2 103 22 29 29 Distance to South from Source to thickness (m) ‐ Segment 3 (2,000 + m) CSD assumed at 13.7 m

Min Max Mean St. Dev. 95% CL ‐ 10 2 21 5 5 6

Thick 5 2 37 7 9 9

(cm) 1 2 81 16 23 22

ness 0.5 2 97 18 26 25

Sediment 0.1 2 101 22 29 29

Port Everglades, Florida Project December 2020 I‐55 Appendix I Sediment Spillage

Figure I‐15. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 2: a CSD with spill at the cutterhead.

Port Everglades, Florida Project December 2020 I‐56 Appendix I Sediment Spillage

Table I‐22. Estimates of Exposure acreage for each benthos category for a given pre‐defined value of sedimentation exposure for Scenario 2: a CSD with spill at the cutterhead.

Scenario 2

Segment 1 Segment 2 Segment 3 5 cm 1 cm 0.5 cm 0.1 cm 10 cm 5 cm 1 cm 0.5 cm 0.1 cm 10 cm 5 cm 1 cm 0.5 cm 0.1 cm 10 cm Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ Acre‐ age Habitat Type age age age age age age age age age age age age age age Acropora cervicornis Aggregated Patch Reef 6.99 0.66 1.94 0.76 0.21 Artificial 0.46 4.60 2.80 1.70 Colonized Pavement Continuous Seagrass Discontinuous Seagrass Inlet Channel 3.55 4.07 0.76 0.57 0.62 0.08 Inner Reef 0.30 0.33 2.44 1.14 0.50 0.28 0.22 1.55 0.63 0.32 Middle Reef 1.15 1.72 4.06 1.92 0.95 Nearshore Ridge Complex 0.25 2.41 11.68 4.73 1.97 Outer Reef 0.13 0.18 0.51 0.23 0.09 2.81 1.74 4.72 1.77 0.49 Patch Reef Ridge 9.38 1.17 3.10 1.07 0.28 Sand 0.36 1.46 0.35 0.21 4.02 4.67 14.05 5.73 2.73 3.74 0.52 1.54 0.66 0.19 Sand Borrow Area

Scattered Rock in Unconsoli‐ 0.65 0.75 1.04 0.66 0.37 0.00 dated Sediment

Port Everglades, Florida Project December 2020 I‐57 Appendix I Sediment Spillage

I.9.5.8 Scenario 4

Scenario 4 considers spillage from mechanical dredging. As discussed above spill from a barge decant are assumed to be zero for the coarse material. The spill rate for mechanical dredging is relatively small at an assumed rate of 2.5%. As a result, the total spill volume is only 56,200 cy. Of that quantity 23,400 cy is expected to reach the resources with the remainder settling out in the inner harbor, north or south of the port and within the direct impact area of the channel. Spill occurs throughout the up cycle in mechanical dredging with a bias to spill at the bottom and at the surface. To account for this bias, it was assumed that 40% of the spill occurs near the bed, 20% at mid‐depth, and the remaining 40% near the surface. These assumptions combined with the very long tailed distributions of mechanical dredging (derived from riverine observations with high flows) result in the majority of the spill be confined within 200 m of the source, but thicknesses of up to 0.1 cm extending to over 500 m north of the channel as seen in Table I‐23 and Figure I‐16. The acreage estimates of exposure is presented in Table I‐24.

Table I‐23. Distance north and south of the channel of sedimentation thickness under scenario 4: mechanical dredge with barge decant for segments 1 (A), 2 (B), and 3 (C). (A) – Segment 1 Distance to North from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) Mechanical Dredge Min Max Mean St. Dev. 95% CL

‐ 10 1 11 7 3 8 5 4 21 16 4 17 Thick

(cm) 1 16 90 62 23 66

ness 0.5 18 189 95 49 104

Sediment 0.1 24 530 173 130 196 Distance to South from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m)

Mechanical Dredge Min Max Mean St. Dev. 95% CL

‐ 10 1 8 5 2 5 5 4 14 10 4 11 Thick

(cm) 1 14 67 47 15 50

ness 0.5 17 125 74 31 80

Sediment 0.1 23 425 155 109 175

(B) Segment 2 Distance to North from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) Mechanical Dredge Min Max Mean St. Dev. 95% CL

‐ 10 1 11 6 3 6 5 4 21 15 5 16 Thick

(cm) 1 39 88 74 17 77

ness 0.5 51 189 121 45 130

Sediment 0.1 53 530 231 144 257

Port Everglades, Florida Project December 2020 I‐58 Appendix I Sediment Spillage

Distance to South from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m)

Mechanical Dredge Min Max Mean St. Dev. 95% CL

‐ 10 1 7 4 2 4 5 4 14 9 4 9 Thick

(cm) 1 33 67 54 10 56

ness 0.5 44 125 90 24 95

Sediment 0.1 53 425 208 116 229

(C) Segment 3 Distance to North from Source to thickness (m) ‐ Segment 3 (2,000 + m) Mechanical Dredge Min Max Mean St. Dev. 95% CL

‐ 10 1 9 5 3 5 5 4 17 12 5 13 Thick

(cm) 1 37 83 66 14 69

ness 0.5 48 157 109 36 116

Sediment 0.1 53 485 223 134 247 Distance to South from Source to thickness (m) ‐ Segment 3 (2,000 + m)

Mechanical Dredge Min Max Mean St. Dev. 95% CL

‐ 10 1 6 3 2 3 5 2 12 7 3 8 Thick

(cm) 1 33 59 49 8 50

ness 0.5 42 105 81 19 84

Sediment 0.1 53 425 200 110 220

Port Everglades, Florida Project December 2020 I‐59 Appendix I Sediment Spillage

Figure I‐16. Estimation of maximum distance from the channel to various sedimentation thickness exposure values for Scenario 4: mechanical dredge.

Port Everglades, Florida Project December 2020 I‐60 Appendix I Sediment Spillage

Table I‐24. Estimates of Exposure acreage for each benthos category for a given pre‐defined value of sedimentation exposure for Scenario 4: mechanical dredge.

Scenario 4

Segment 1 Segment 2 Segment 3 1 cm 10 cm 5 cm 1 cm 10 cm 5 cm 1 cm 10 cm 5 cm 1 cm 10 cm 5 cm 1 cm 10 cm 5 cm Acre‐ Acreage Acreage Acreage Acreage Acreage Acreage Acreage Acreage Acreage Acreage Acreage Acreage Acreage Acreage Habitat Type age Acropora cervicornis Aggregated Patch 6.42 0.29 2.45 2.93 17.30 Reef Artificial 5.19 15.99 50.02 0.32 18.47 Colonized Pavement Continuous Seagrass Discontinuous

Seagrass Inlet Channel 0.77 2.15 5.46 0.21 0.31 0.75 Inner Reef 0.02 0.20 2.75 4.06 20.21 0.08 0.14 1.81 3.17 14.06 Middle Reef 0.22 0.66 5.93 9.09 24.66 Nearshore Ridge 0.09 13.56 15.14 67.21 0.06 1.54 Complex Outer Reef 0.07 0.06 0.62 0.67 4.54 1.36 0.76 6.12 6.43 32.41 Patch Reef Ridge 8.41 0.49 3.92 3.61 16.81 Sand 1.92 2.65 14.04 1.15 2.13 19.23 22.85 91.13 3.32 0.23 2.00 2.78 20.11 Sand Borrow Area Scattered Rock in Unconsolidated Sed‐ 2.56 0.22 0.31 1.86 2.71 4.28 0.00 iment

Port Everglades, Florida Project December 2020 I‐61 Appendix I Sediment Spillage

I.9.6 Summary

This analysis used available literature and data to estimate the expected areas of sedimentation exposure from coarse grained material dredged during the Port Everglades Deepening Project. The total quantity of dredged material was estimated from which the expected quantity of coarse‐grained material was estimated. Based on the literature, estimates of spillage for the various dredging methodologies considered were used to determine the quantity of coarse material that could be spilled during the project. From there, assumptions were made regarding the quantity of material from the inner port that reaches the offshore area, the distance offshore that inner harbor sediment will travel, and assumptions of the percentage of the time the offshore flow is north or south directed. These assumptions were based on available literature, model results, and engineering judgment and are summarized in Table I‐18. They resulted in a total quantity of coarse material that is expected to be spilled and distributed both north and south of the offshore channel which are summarized in Table I‐25. Depending on the type of equipment to be used in the scenario, representative concentration versus distance curves were developed based on observations in the literature of suspended sediment concentration and adjustments for dilution of the measurements. Finally, the available sediment and maximum expected excursion distance based on local currents and the sediment fall velocity was scaled to the distribution and the distance where the sediment thickness reaches pre‐defined values was determined.

The values presented in this analysis are expected to be conservative given that the time component is not accounted for and that this model applies to far field plume estimates and does not account for density driven plumes. In reality over the multi‐year project length energetic events will occur which disrupt the sediment, resuspend it and further distribute it. What is presented here assumes that all the material is deposited at once. Different fall velocities and horizontal current fields were analyzed to attempt to conservatively bookend expected conditions. Also a density driven plume would settle in a much more localized area as opposed to the far field spreading predicted here. While sediment thickness values are presented, they are likely better called thickness exposure values due to the lack of a time component (i.e. at this distance out there is the potential to be exposed to sedimentation up to this amount during the dredging process). Concentration and divergence of flow patterns that vary spatially and temporally and unavailable for inclusion in this analysis, in addition to other assumptions included, are expected to influence spillage distribution patterns and differ from distributions presented from this analysis.

The scenarios showed that overflow is the largest contributor when it comes to potential sedimentation and introducing sediment near the surface can increase the potential of exposure far from the source. This can somewhat be mitigated by requiring overflow to be released as deep in the water column as possible. Not allowing overflow can be economically costly, but results in a large reduction in the expected area of sedimentation exposure. An enhanced blasting plan coupled with a mechanical dredge will likely reduce sedimentation exposure as well, especially those above 0.1 cm.

Table I‐25. Summary of scenarios and spill volumes for coarse sediment. Scenario 1 Scenario 2/3 Scenario 4 Description CSD with overflow CSD with decant/ CSD Mechanical dredge with direct pump to disposal area Source CSD Overflow CSD Mechanical Spill Volume Segment 1 38,715 16,049 38,715 8,992

Port Everglades, Florida Project December 2020 I‐62 Appendix I Sediment Spillage

(cy) Segment 2 38,715 16,049 38,715 8,992 Segment 3 23,128 9,587 23,128 5,372 Total 100,559 41,684 100,559 23,356

I.9.7 References

Becker, J., van Eekelen, E., van Wiechen, J., de Lange, W., Damsma, T., Smolders, T., and M. van Koningsveld, 2015. Estimating source terms for far field dredge plume modelling. Journal of Environmental Management. 149, 282‐293.

Collins, M.A., 1995. Dredging‐Induced Near‐Field Resuspended Sediment Concentrations and Source Strengths. USACE ERDC MP D‐95‐2.

Foster, T. and J. Van Berkel, 2017. Proactive and Adaptive Measures for the Management of Coastal Development Induced Sediment Plume Impacts. DHI presentation on 27 April 2018, Ft. Lauderdale, FL.

Kemps, H. and R. Masini, 2017. Estimating dredge source terms – a review of contemporary practice in the context of Environmental Impact Assessment in Western Australia. WAMSI Dredging Science Node

Kuo, A. Y., and D. F. Hayes, 1991. A model for turbidity plume induced by bucket dredge. Journal of Waterways, Port, Coastal, and Ocean Engineering 117(6):610‐623. American Society of Civil Engineers

Kuo, A. Y., Welch, C. S., and R. J. Lukens, 1985. Dredge induced turbidity plume model. Journal of Waterways, Port, Coastal, and Ocean Engineering 111(3):476‐495. American Society of Civil Engineers

Mills, D. and H. Kemps, 2016. Generation and release of sediments by hydraulic dredging: a review. WAMSI Dredging Science Node

Nichols, M., Diaz, R.J., and Schaffner, L.C., 1990. Effects of hopper dredging and sediment dispersion, Chesapeake Bay. Environ Geol Water Sci. Vol 15, No. 1, 31 – 43.

Schroeder, P.R, and S. Pranger, 2018. Particle Size Distribution of Port Everglades Outer Entrance Channel Materials and Settling Properties of Sandstone Materials. USACE ERDC.

Schroeder, P., Pranger, S., Wade, R., McComas, B., and J. Smith, 2017. Characterization of Port Everglades Material for Settling and Erosion Properties, USACE ERDC.

Soloviev, A.V., Dean, C.W., Weisberg, R.H., Luther, M.E., and J. Wood, 2015. ADCP Mooring System on the Southeast Florida Shelf. NSU Oceanography Faculty Reports, 12 p. http://nsuworks.nova.edu/occ_facreports/52

Spearman, J., 2015. A review of the physical impacts of sediment dispersion from aggregate dredging. Marine Pollution Bulletin, Vol. 94, Issues 1 – 2, 260 – 277.

Port Everglades, Florida Project December 2020 I‐63 Appendix I Sediment Spillage

USACE Dredging and Dredged Material Management Engineer Manual (USACE 2015) United States Army Corps of Engineers – Jacksonville District, Engineering Division, Geosystems Branch (SAJ EN‐G), 2017. MFR – Port Everglades Harbor Deepening (Project No. 452862), Review of PD‐EC Dredging Scenarios. 48 p.

Walker, B. K. and K. Klug, 2014. Southeast Florida Shallow‐Water Habitat Mapping & Coral Reef Community Characterization. Florida DEP Coral Reef Conservation Program Report: 1 ‐71. http://nsuworks.nova.edu/occ_facreports/87.

Port Everglades, Florida Project December 2020 I‐64 Appendix I Sediment Spillage

I.10 Addendum 2 – Distance Tables with Statistics

Table I‐26. Distance north and south of the channel of sedimentation thickness under scenario 1: a CSD with overflow at a release depth of 3.0 m for segments 1 (A), 2 (B), and 3 (C) for fines (d50 < 0.062 mm). (A) – Segment 1 Distance to North from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) 3.0 m Overflow Release Depth (CSD assumed at 13.7 m) Min Max Mean St. Dev. 95% CL 10 22 70 53 15 57 5 33 132 93 35 102

Thickness 1 74 405 238 80 258 (cm) 0.5 106 998 365 191 414

Sediment 0.1 141 2375 910 566 1056 Distance to South from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) 3.0 m Overflow Release Depth (CSD assumed at 13.7 m)

Min Max Mean St. Dev. 95% CL 10 17 46 29 10 32 5 25 84 66 21 71

Thickness 1 48 254 167 63 183 (cm) 0.5 88 595 276 108 304

Sediment 0.1 131 1972 675 404 779

(B) Segment 2 Distance to North from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) 3.0 m Overflow Release Depth (CSD assumed at 13.7 m) Min Max Mean St. Dev. 95% CL 10 15 38 24 9 27 5 24 73 56 16 60

Thickness 1 48 235 152 63 168 (cm) 0.5 77 440 245 84 267

Sediment 0.1 127 1817 589 372 685 Distance to South from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) 3.0 m Overflow Release Depth (CSD assumed at 13.7 m)

Min Max Mean St. Dev. 95% CL

‐ 21 13 4 14

k 10 10 Sedi ment 18 48 31 11 34 Thi 5

Port Everglades, Florida Project December 2020 I‐65 Appendix I Sediment Spillage

1 46 184 122 50 135 0.5 54 259 172 62 188 0.1 117 1414 464 287 538

(C) Segment 3 Distance to North from Source to thickness (m) ‐ Segment 3 (>2,000 m) 3.0 m Overflow Release Depth (CSD assumed at 13.7 m) Min Max Mean St. Dev. 95% CL 10 10 17 12 2 12 5 17 40 24 9 26

Thickness 1 47 164 100 50 113 (cm) 0.5 64 238 144 68 162

Sediment 0.1 113 985 504 260 571 Distance to South from Source to thickness (m) ‐ Segment 3 (>2,000 m) 3.0 m Overflow Release Depth (CSD assumed at 13.7 m)

Min Max Mean St. Dev. 95% CL 10 1 9 6 2 7 5 3 21 13 5 14

Thickness 1 37 113 88 28 95 (cm) 0.5 51 188 133 49 145

Sediment 0.1 102 588 334 133 368

Table I‐27. Distance north and south of the channel of sedimentation thickness under scenario 2: a CSD with barge decanting at 3.0 m water depth for segments 1 (A), 2 (B), and 3 (C) for fines (d50 < 0.062 mm). (A) – Segment 1 Distance to North from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) 3.0 m Decant Release Depth (CSD assumed at 13.7 m) Min Max Mean St. Dev. 95% CL 10 4 16 7 5 8 5 7 58 16 12 19

Thickness 1 17 228 60 54 74 (cm) 0.5 21 306 85 80 106

Sediment 0.1 83 475 142 134 165 Distance to South from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m)

Port Everglades, Florida Project December 2020 I‐66 Appendix I Sediment Spillage

3.0 m Decant Release Depth (CSD assumed at 13.7 m)

Min Max Mean St. Dev. 95% CL 10 2 11 5 3 5 5 5 21 9 6 10

Thickness 1 14 176 45 40 55 (cm) 0.5 18 253 68 62 84

Sediment 0.1 43 381 123 113 145

(B) – Segment 2 Distance to North from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) 3.0 m Decant Release Depth (CSD assumed at 13.7 m) Min Max Mean St. Dev. 95% CL 10 3 11 5 3 5 5 6 19 8 5 10

Thickness 1 13 169 43 38 53 (cm) 0.5 17 245 65 60 81

Sediment 0.1 28 369 124 114 147 Distance to South from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) 3.0 m Decant Release Depth (CSD assumed at 13.7 m)

Min Max Mean St. Dev. 95% CL 10 1 9 3 2 4 5 3 12 6 3 6

Thickness 1 11 118 30 26 36 (cm) 0.5 15 193 50 45 61

Sediment 0.1 24 287 107 97 130

(C) – Segment 3 Distance to North from Source to thickness (m) ‐ Segment 3 (>2,000 m) 3.0 m Decant Release Depth (CSD assumed at 13.7 m) Min Max Mean St. Dev. 95% CL 10 2 9 4 2 4 5 4 17 7 4 8

Thickness 1 13 168 33 33 42 (cm) 0.5 16 244 52 50 65

Sediment 0.1 24 367 119 89 142 Distance to South from Source to thickness (m) ‐ Segment 3 (>2,000 m)

Port Everglades, Florida Project December 2020 I‐67 Appendix I Sediment Spillage

3.0 m Decant Release Depth (CSD assumed at 13.7 m)

Min Max Mean St. Dev. 95% CL 10 1 7 3 2 3 5 2 10 4 3 5

Thickness 1 11 117 22 22 28 (cm) 0.5 14 192 39 38 49

Sediment 0.1 22 284 94 82 115

Table I‐28. Distance north and south of the channel of sedimentation thickness under scenario 3: a CSD with direct pump to offshore disposal for segments 1 (a), 2 (b), and 3 (c) for fines (d50 < 0.062 mm). (A) – Segment 1 Distance to North from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) CSD assumed at 13.7 m – direct pump Min Max Mean St. Dev. 95% CL 10 2 18 6 4 7 5 4 56 12 12 15

Thickness 1 7 225 43 56 58 (cm) 0.5 13 300 55 85 77

Sediment 0.1 23 465 68 107 92 Distance to South from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) CSD assumed at 13.7 m – direct pump

Min Max Mean St. Dev. 95% CL 10 2 18 4 3 5 5 3 24 7 5 8

Thickness 1 6 174 32 42 43 (cm) 0.5 10 249 49 64 65

Sediment 0.1 14 376 66 95 90

(B) – Segment 2 Distance to North from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) CSD assumed at 13.7 m – direct pump Min Max Mean St. Dev. 95% CL

‐ 1 18 4 3 5

k 10 Sedi ment 3 24 7 5 8 Thi 5

Port Everglades, Florida Project December 2020 I‐68 Appendix I Sediment Spillage

1 6 167 31 40 41 0.5 10 242 47 62 63 0.1 16 364 66 106 91 Distance to South from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) CSD assumed at 13.7 m – direct pump

Min Max Mean St. Dev. 95% CL 10 1 18 3 2 4 5 2 24 5 3 6

Thickness 1 5 116 22 27 29 (cm) 0.5 8 191 36 47 48

Sediment 0.1 13 310 63 103 89

(C) – Segment 3 Distance to North from Source to thickness (m) ‐ Segment 3 (>2,000 m) CSD assumed at 13.7 m – direct pump Min Max Mean St. Dev. 95% CL 10 1 18 3 2 4 5 2 24 5 3 5

Thickness 1 5 115 22 26 28 (cm) 0.5 8 190 35 46 47

Sediment 0.1 12 310 63 103 89 Distance to South from Source to thickness (m) ‐ Segment 3 (>2,000 m) CSD assumed at 13.7 m – direct pump

Min Max Mean St. Dev. 95% CL 10 1 18 3 2 3 5 1 24 3 3 4

Thickness 1 4 66 13 14 17 (cm) 0.5 5 139 26 33 34

Sediment 0.1 8 256 55 90 78

Port Everglades, Florida Project December 2020 I‐69 Appendix I Sediment Spillage

Table I‐29. Distance north and south of the channel of sedimentation thickness under scenario 4: mechanical dredge with barge decant for segments 1 (a), 2 (b), and 3 (c) for fines (d50 < 0.062 mm). (A) – Segment 1 Distance to North from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) Mechanical released throughout water column w/ decant Min Max Mean St. Dev. 95% CL 10 1 14 5 4 7 5 14 27 17 4 18

Thickness 1 46 124 102 27 114 (cm) 0.5 108 305 224 54 247

Sediment 0.1 697 1218 928 205 1014 Distance to South from Source to thickness (m) ‐ Segment 1 (0 ‐ 1,000 m) Mechanical released throughout water column w/ decant

Min Max Mean St. Dev. 95% CL 10 0 5 1 2 1 5 5 17 8 3 10

Thickness 1 42 68 54 11 59 (cm) 0.5 46 172 134 39 150

Sediment 0.1 413 1071 639 140 699

(B) – Segment 2 Distance to North from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) Mechanical released throughout water column w/ decant Min Max Mean St. Dev. 95% CL 10 0 4 1 1 1 5 2 15 6 4 7

Thickness 1 37 56 46 9 49 (cm) 0.5 46 136 109 31 122

Sediment 0.1 347 922 550 121 601 Distance to South from Source to thickness (m) ‐ Segment 2 (1,000 ‐ 2,000 m) Mechanical released throughout water column w/ decant

Min Max Mean St. Dev. 95% CL

10 0 4 0 1 1 ) 5 0 6 1 2 2 ( Sediment Thickness 1 23 42 29 6 31

Port Everglades, Florida Project December 2020 I‐70 Appendix I Sediment Spillage

0.5 43 72 58 11 63 0.1 230 518 337 70 367

(C) – Segment 3 Distance to North from Source to thickness (m) ‐ Segment 3 (>2,000 m) Mechanical released throughout water column w/ decant Min Max Mean St. Dev. 95% CL 10 0 4 0 1 1 5 0 5 1 1 1

Thickness 1 20 36 24 5 26 (cm) 0.5 39 60 48 10 52

Sediment 0.1 201 438 297 51 319 Distance to South from Source to thickness (m) ‐ Segment 3 (>2,000 m) Mechanical released throughout water column w/ decant

Min Max Mean St. Dev. 95% CL 10 0 4 0 1 1 5 0 4 0 1 1

Thickness 1 11 23 14 4 16 (cm) 0.5 24 43 30 6 33

Sediment 0.1 46 244 191 56 214

Port Everglades, Florida Project December 2020 I‐71