The Design, Feasibility and Cost Analysis of Sea Barrier Systems in Norfolk, Virginia and the Comparative Cost of Shoreline Barriers by Charles H

The Design, Feasibility and Cost Analysis of Sea Barrier Systems in Norfolk, Virginia and the Comparative Cost of Shoreline Barriers by Charles H. Hasenbank Submitted to the Department of Mechanical Engineering in partial fulfillment of the requirements for the degrees of Naval Engineer and Master of Science in Mechanical Engineering at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY May 2020 © Massachusetts Institute of Technology 2020. All rights reserved.

Author...... Department of Mechanical Engineering May 15, 2020

Certified by...... Daniel Frey Professor of Mechanical Engineering Thesis Supervisor

Accepted by ...... Nicolas Hadjiconstantinou Chairman, Department Committee on Graduate Theses 2 The Design, Feasibility and Cost Analysis of Sea Barrier Systems in Norfolk, Virginia and the Comparative Cost of Shoreline Barriers by Charles H. Hasenbank

Submitted to the Department of Mechanical Engineering on May 15, 2020, in partial fulfillment of the requirements for the degrees of Naval Engineer and Master of Science in Mechanical Engineering

Abstract Protecting a coastline from the damage of a storm surge, or tidal flooding associated with sea level rise, is a challenging and costly engineering endeavor. Low lying properties located directly on an ocean coastline are limited in protective solutions to include constructing shoreline barriers, increasing building elevations, or relocation. However, shoreline properties on an estuary are afforded the additional protective option of a dynamic sea barrier spanning the mouth of the bay or river. The Delta Works projects in the Netherlands pioneered the design and construction of large scale dynamic sea barriers. Although similar projects have been built or proposed, the high costs have minimized wide spread implementation. Even with positive benefit-cost ratios of prevented property damage to sea barrier cost, the will- ingness to fund these multi-billion dollar projects is reduced when the probability of extreme coastal flooding is associated with 100 to 1000 year storms. However, ifsea level rise shifts the flooding probability to include king tides and annual storms, the perspective regarding the relative cost of a sea barrier system may soon change. This study serves as a design, feasibility and cost analysis of potential sea barrier systems in the Chesapeake Bay near Norfolk, Virginia. Several sea barrier concept designs were proposed, and analyzed against intermediate sea level rise scenarios for the year 2100, to determine feasibility based on topography and projected tide levels. The cost and performance of the design concepts were then examined to determine an optimal design. Finally, the cost of the optimal sea barrier system was compared to the notional cost of installing shoreline barriers along the extent of the estuary, to determine the most cost effective method of coastal flooding protection.

Thesis Supervisor: Daniel Frey Title: Professor of Mechanical Engineering

3 4 Acknowledgments

Dating back to my undergraduate studies as an Ocean Engineer, I have always enjoyed exploring the topics associated with coastline flooding protection and mitigation. In a era when sea level rise has the potential of severely disrupting coastal communities on a scale and frequency not previously imaginable, this field of study has become increasingly important. With that in mind, I want to thank Professor Daniel Frey, of the Mechanical Engineering Department at MIT, for supporting me as I studied this topic and for granting me the leeway to establish the bounds of the thesis topic. Additionally, I would like to thank Professor David Kriebel of the Naval Architecture and Ocean Engineering Department at USNA, for providing guidance throughout the course of study as a subject matter expert in this field of study. Lastly, I would like to thank my family for their consistent support throughout my time at MIT.

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6 Contents

1 Introduction 15 1.1 Project Background and Rationale ...... 16 1.2 Sea Level Rise Trends and Projections ...... 21 1.3 Mitigation Projects and Proposals ...... 29 1.4 Thesis Contributions ...... 33

2 Sea Barrier Feasibility Analysis 35 2.1 Study Locations ...... 35 2.2 Tidal Data and Sea Level Projections ...... 38 2.3 High Water Analysis ...... 42 2.3.1 Naval Station Norfolk Projected High Water Analysis . . . . . 42 2.3.2 Norfolk Naval Shipyard Projected High Water Analysis . . . . 44 2.4 Low Water and Mean Sea Level Analysis ...... 47 2.4.1 Naval Station Norfolk Projected Low Water Analysis . . . . . 48 2.4.2 Norfolk Naval Shipyard Projected Low Water Analysis . . . . 49 2.5 Norfolk, VA Storm Flooding Comparison ...... 50

3 Sea Barrier Concept Designs 51 3.1 Sea Barrier Concept Design One ...... 54 3.2 Sea Barrier Concept Design Two ...... 56 3.3 Sea Barrier Concept Design Three ...... 58 3.4 Sea Barrier Design Four ...... 60 3.5 Sea Barrier Design Five ...... 61

7 3.6 Sea Barrier Design Six ...... 62

4 Sea Barrier Performance Analysis 63 4.1 OMOE: Project Scale Analysis ...... 67 4.2 OMOE: Protection Area Analysis ...... 69 4.3 OMOE: Perimeter Flooding Analysis ...... 70 4.4 OMOE: Frequency of Operation Analysis ...... 72 4.5 OMOE: Maritime Traffic Impact Analysis ...... 73 4.6 OMOE: Environmental Impact Analysis ...... 75 4.7 OMOE Results ...... 76

5 Sea Barrier Cost Analysis 79 5.1 Cost Model ...... 88 5.2 Cost Analysis ...... 92

6 Sea Barrier Selection and Analysis 97 6.1 Cost vs Performance Analysis ...... 97

7 Shoreline Infrastructure Analysis 101 7.1 Shoreline Barrier System Cost Factors ...... 103 7.2 Shoreline Infrastructure Cost Analysis ...... 106 7.3 Hybrid Shoreline Barrier Cost Analysis ...... 110

8 Conclusion 117 8.1 Project Accomplishments and Findings ...... 117 8.2 Areas for Further Work ...... 124

A Sea Barrier Cost Model 125

B Sea Barrier Cost Analysis 139

C Shoreline Barrier Cost Model 145

D Shoreline Barrier Cost Analysis 149

8 List of Figures

1-1 High Tide Nuisance Flooding ...... 16 1-2 Nuisance Flooding Frequency at USNA ...... 17 1-3 Sewells Point Tide Station Flood Stage Events (1930s-2010s) . . . . . 18 1-4 Hampton Roads and Major Maritime Facilities ...... 20 1-5 Topographic Map of Norfolk, VA with Shoreline Elevations ...... 21 1-6 NOAA Extreme Water Levels for Norfolk, VA ...... 22 1-7 NOAA Sea Level Rise Trends for Norfolk, VA ...... 22 1-8 Sea Level Rise and Norfolk, VA ...... 23 1-9 Global Sea Level Rise Overview ...... 24 1-10 Regional Sea Level Rise Overview ...... 25 1-11 Sea Level Rise Projection Types ...... 26 1-12 Sea Level Rise Scenario Curves ...... 27 1-13 National Climate Assessment GMSL Scenarios Overview ...... 28 1-14 Flood Management Feasibility and Mitigation Studies ...... 30

2-1 Study Location One (Naval Station Norfolk) ...... 36 2-2 Study Location Two (Norfolk Naval Shipyard) ...... 37 2-3 Naval Station Norfolk Tidal and Extreme Water Data ...... 38 2-4 Norfolk Naval Shipyard Tidal and Extreme Water Data ...... 38 2-5 Naval Station Norfolk Sea Level Projections ...... 39 2-6 Norfolk Naval Shipyard Sea Level Projections ...... 39 2-7 NOAA Sea Level Rise Viewer ...... 41 2-8 Naval Station Norfolk MHHW Tidal Projection (Year 2100) . . . . . 42

9 2-9 Naval Station Norfolk 1-YR Storm Projection (Year 2100) ...... 43 2-10 Naval Station Norfolk 10-YR Storm Projection (Year 2100) ...... 43 2-11 Naval Station Norfolk 100-YR Storm Projection (Year 2100) . . . . . 44 2-12 Norfolk Naval Shipyard MHHW Tidal Projection (Year 2100) . . . . 45 2-13 Norfolk Naval Shipyard 1-YR Storm Projection (Year 2100) . . . . . 45 2-14 Norfolk Naval Shipyard 10-YR Storm Projection (Year 2100) . . . . . 46 2-15 Norfolk Naval Shipyard 100-YR Storm Projection (Year 2100) . . . . 46 2-16 Naval Station Norfolk MLLW Tidal Projection (Year 2100) ...... 48 2-17 Naval Station Norfolk LMSL Tidal Projection (Year 2100) ...... 48 2-18 Norfolk Naval Shipyard MLLW Tidal Projection (Year 2100) . . . . . 49 2-19 Norfolk Naval Shipyard LMSL Tidal Projection (Year 2100) . . . . . 49 2-20 Norfolk, VA Study Area Storm Surge Flooding Comparison ...... 50

3-1 Arthur Kill Barrier Concept in the Greater New York City Area . . . 52 3-2 Jamaica Bay Barrier Concept in the Greater New York City Area . . 53 3-3 Sea Barrier Concept Design One Chart View ...... 54 3-4 Sea Barrier Concept Design One Satellite View ...... 55 3-5 Sea Barrier Concept Design Two Chart View ...... 56 3-6 Sea Barrier Concept Design Two Satellite View ...... 57 3-7 Sea Barrier Concept Design Three Chart View ...... 58 3-8 Sea Barrier Concept Design Three Satellite View ...... 59 3-9 Sea Barrier Concept Design Four Chart View ...... 60 3-10 Sea Barrier Concept Design Four Satellite View ...... 60 3-11 Sea Barrier Concept Design Five Satellite View ...... 61 3-12 Sea Barrier Concept Design Six Satellite View ...... 62

4-1 Delta Works: Maeslantkering Sector Gate ...... 64 4-2 Delta Works: Eastern Scheldt Surge Barrier ...... 64 4-3 Chesapeake Bay Region DOD Installations ...... 69 4-4 Areas of Probable Perimeter Flooding ...... 71 4-5 Mouth of the Chesapeake Bay Tides (01-31JAN2020) ...... 72

10 4-6 Norfolk, Virginia Port Facilities ...... 74 4-7 Environmental Impact Areas ...... 75 4-8 OMOE Results Table ...... 77 4-9 FOM Comparison Graph ...... 77 4-10 Weighted Sum Comparison Graph ...... 77 4-11 Sea Barrier Concept Five Overview ...... 78

5-1 Delta Works Barrier Overview ...... 79 5-2 Hurricane and Storm Damage Risk Reduction System (HSDRRS) . . 80 5-3 GCCPRD Storm Surge Suppression Study ...... 80 5-4 USACE Coastal Texas Protection and Restoration Study ...... 81 5-5 USACE Norfolk Coastal Risk Management Study ...... 82 5-6 USACE New York and New Jersey Harbor and Tributaries Study . . 83 5-7 HSDRRS: Seabrook (Top) and West Closure (Bottom) ...... 85 5-8 USACE Coastal Texas Study Preliminary Cost Ranges ...... 85 5-9 USACE Norfolk Coastal Risk Management Study Cost Data . . . . . 86 5-10 GCCPRD Storm Surge Suppression Study Cost Data ...... 86 5-11 Sea Barrier Reference Data for the USACE NY-NJ Study ...... 87 5-12 USACE NY-NJ Study Verrazano Narrows Sea Barrier Section Plan . 88 5-13 USACE NY-NJ Study Regression Formula and Data Plot ...... 89 5-14 Reference Sea Barrier Data Table ...... 90 5-15 Minitab Fitted Regression Model Summary ...... 90 5-16 Minitab Fitted Regression Line Plot ...... 91 5-17 Sea Barrier Design Concept One Diagram ...... 92 5-18 Sea Barrier Design Concept Two Diagram ...... 93 5-19 Sea Barrier Design Concept Three Diagram ...... 94 5-20 Sea Barrier Design Concept Four Diagram ...... 94 5-21 Sea Barrier Design Concept Five Diagram ...... 95 5-22 Sea Barrier Design Concept Six Diagram ...... 96

6-1 Cost and Performance Data for the Sea Barrier Concepts ...... 97

11 6-2 Cost vs Performance Analysis for the Sea Barrier Concepts ...... 98 6-3 Optimal Design: Sea Barrier Concept Five ...... 99 6-4 Sea Barrier Concept Five Design Specifications ...... 100 6-5 Sea Barrier Concept Five Inner and Outer Barrier ...... 100

7-1 City of Chesapeake, Virginia Tidal Shoreline Overview ...... 102 7-2 Shoreline Infrastructure Cost Factors (FY19 USD/LF) ...... 103 7-3 Shoreline Analysis One: Barrier Types and Cost Factors ...... 104 7-4 Shoreline Analysis Two: Shoreline Barrier Cost Factors ...... 106 7-5 VIMS Shoreline Data Sets (Denoted with Blue Stars) ...... 107 7-6 Shoreline Infrastructure Analysis Area ...... 108 7-7 Shoreline Infrastructure Cost Analysis Results ...... 109 7-8 Hybrid Shoreline Barrier Design ...... 110 7-9 Hybrid Shoreline Barrier Section Overview ...... 111 7-10 Norfolk Shoreline Barrier Design Comparison ...... 112 7-11 Waterfront Layout of the Elizabeth River Shipyards ...... 113 7-12 Hybrid Shoreline Barrier Cost Analysis Overview ...... 114

8-1 Hurricane Isabel Surge Levels (Norfolk, VA) ...... 118 8-2 Flooding Analysis at NSN and NNSY in 2100 ...... 118 8-3 Recommended Sea Barrier Concept ...... 119 8-4 Sea Barrier Concept Overview ...... 120 8-5 Category Four Hurricane Surge Projections ...... 123 8-6 Comparable Study Location: San Francisco Bay ...... 124

B-1 Chesapeake Bay Chart ...... 139

C-1 Shoreline Infrastructure Cost Factors (FY19 USD/LF) ...... 145

D-1 Shoreline Analysis One: Shoreline Infrastructure ...... 149 D-2 Shoreline Analysis Two: Shoreline Hybrid Barrier ...... 149

12 List of Tables

1.1 Norfolk, VA Tidal Datum Changes ...... 29

2.1 Naval Station Norfolk 2020 and 2100 Tidal Data Comparison . . . . . 40 2.2 Norfolk Naval Shipyard 2020 and 2100 Tidal Data Comparison . . . . 40 2.3 Projected Tidal Data Above Year 2020 MHHW ...... 41 2.4 Norfolk, VA Tidal Projections Above Year 2020 MHHW ...... 41

4.1 OMOE Performance Category Weight Factors ...... 66 4.2 Navigable Section Comparison ...... 67 4.3 Auxiliary Section Comparison ...... 67 4.4 Static Section Comparison ...... 68 4.5 FOM: Project Scale ...... 68 4.6 FOM: Protection Area ...... 69 4.7 FOM: Perimeter Flooding ...... 71 4.8 FOM: Frequency of Operation ...... 72 4.9 FOM: Maritime Traffic Impact ...... 73 4.10 FOM: Maritime Traffic Impact ...... 74 4.11 FOM: Environmental Impact ...... 76 4.12 Sea Barrier Concept Five Specifications ...... 78

5.1 Sea Barrier Design Concept One Cost Estimates ...... 92 5.2 Sea Barrier Design Concept Two Cost Estimates ...... 93 5.3 Sea Barrier Design Concept Three Cost Estimates ...... 93 5.4 Sea Barrier Design Concept Four Cost Estimates ...... 94

13 5.5 Sea Barrier Design Concept Five Cost Estimates ...... 95 5.6 Sea Barrier Design Concept Six Cost Estimates ...... 95 5.7 Sea Barrier Design Concept Cost Comparisons ...... 96

6.1 Sea Barrier Design Concept Five Overview ...... 99

7.1 Barrier Cost Estimates for Shoreline Facilities ...... 116

8.1 Sea Level Rise Projections at Naval Station Norfolk ...... 117

14 Chapter 1

Introduction

In response to the North Sea Flood of 1953, a commission in the Netherlands, designated as the Delta Committee, developed the framework for what would become the pioneering Delta Works flood control system [Watersnood Museum, 2020]. The construction of this elaborate system of flood protection barriers spanned from 1954 to 1997, with a design threshold as stringent as a 1/10,000 year storm for portions of the system [Watersnood Museum, 2020, Bouwer and Vellinga, 2007]. These mar- vels of engineering have become benchmarks for flood protection systems around the world, but the Delta Works design is being revisited to ensure the current flood barriers, and their successors, adequately address the growing threat of sea level rise [Delta Commission, 2008]. Referencing the bold scale of the Delta Works, and the proactive initiatives set forth by a second Delta Committee to address sea level rise, this thesis will examine the potential for a similar approach within the United States. Specifically, this study will conduct a design, feasibility and cost analysis of largescale sea barrier systems, similar to aspects of the Delta Works, for the greater Norfolk, Virginia area. Norfolk is located near the mouth of the Chesapeake Bay in a region known as Hampton Roads, named for the waterway that is situated at the confluence of the James and Elizabeth Rivers. The sea barrier system selected as the optimal design will be compared to the alternative option of constructing shoreline infrastructure throughout Hampton Roads, to determine the most cost effective approach for regional flood management with reference to the impending threat of sea level rise.

15 1.1 Project Background and Rationale

While living in Annapolis, Maryland, I witnessed a troubling trend regarding tidal flooding in low-lying areas at the United States Naval Academy (USNA) and throughout the surrounding community. These flooding events, although usually minor, appeared to be happening more frequently, and apart from storm systems that would have historically been the primary cause of coastal flooding. As I would come to learn, this tidal flooding was not a localized event, but rather an increasingly frequent trend throughout the Chesapeake Bay region, as well as along portions of the East Coast and Gulf Coast of the United States, as outlined in Figure 1-1.

Figure 1-1: High Tide Nuisance Flooding [NOAA, 2018]

As described in Figure 1-1, the cause of these higher tides is sea level rise, and the most frequent result, is localized flooding in low-lying areas during the highest of spring tides. The trend has been coined nuisance flooding because it tends to cause more of an inconvenience than substantial damage [NOAA, 2018]. However, the underlying concern associated with this trend is the increase of the local mean sea level (LMSL). The higher LMSL produces a corresponding increase to the high water levels expected during storm events, in which the damaging storm surges historically associated with 1/100 year storms or greater, begin to occur more frequently.

16 In response to the increased rate of tidal flooding in Annapolis, the Naval Academy formed a Sea Level Rise Advisory Council to examine the issue, and establish mitigation recommendations. In a 2019 report, the council provided data illustrating nuisance flooding occurrences at USNA over the past 90 years, with a near exponen- tial increase in the number of flooding events since the turn of the century asshown in Figure 1-2 [USNA Sea Level Rise Advisory Council, 2019].

Figure 1-2: Nuisance Flooding Frequency at USNA [USNA Sea Level Rise Advisory Council, 2019]

The graphical analysis shown in Figure 1-2 confirms that I really had witnessed a substantial number of tidal flooding events while living in Annapolis, with year over year increases peaking in 2011 with nearly 30 nuisance floods. After departing Annapolis, I would witness the same trend 150 miles to the south while stationed in Norfolk, Virginia. Utilizing National Weather Service (NWS) data of flood stage events recorded at the Sewells Point tide station on Pier 6 of Naval Station Norfolk, Figure 1-3 outlines the number of floods per decade from the 1930s through the 2010s. As established by the NWS, flood stage at this location is 4.5ft above mean lower low water (MLLW) for a minor flood. A moderate flood occurs at 5.5ft above MLLW and a major flood at 6.5ft above MLLW [NWS, 2020]. Similar to the USNA data,the number of minor flooding events in the Norfolk, VA area increased dramatically in recent years with 31 of the 52 recorded floods taking place since 2015 [NWS, 2020]. Based on my experience of working at the naval station during this time period, these

17 minor flood stage events did not impact daily operations, and only produced minor pooling in low-lying, non-developed areas. However, as with the Annapolis data, the primary concern is the underlying cause which points toward an increase in LMSL, and the potential for future storm events to have substantially higher surge levels.

Figure 1-3: Sewells Point Tide Station Flood Stage Events (1930s-2010s)

As illustrated in Figures 1-2 and 1-3, the increased number of tidal flooding events in Annapolis, MD and Norfolk, VA is significant, and has a clear upward trend. Witnessing the frequency of these flooding occurrences first hand, even with the vast majority only being nuisance floods, provided the background interest for this thesis, and the desire to examine the threat of sea level rise, as well as the potential for mitigation efforts in the Chesapeake Bay region. In addition to witnessing the coastal flooding trends while living in Norfolk, Vir- ginia area, I also became acutely aware of the vital importance of this region in supporting United States Navy (USN) operations. Naval Station Norfolk (NSN) is the largest naval complex in the world with approximately 4,600 acres, 4,000 buildings, 14 piers and an airfield [NAVFAC, 2020a]. The base serves as the homeport for approximately 60 ships with over 3,100 ship movements annually [NAVFAC, 2020a,

18 NAVSHIPSO, 2020]. Just a few miles away, on the Elizabeth River, is Norfolk Naval Shipyard (NNSY), one of four public shipyards operated by the USN with over 800 acres and five dry docks. NNSY is the sole public maintenance yard for aircraft carriers on the East Coast, as well as one of the primary submarine maintenance yards [NAVFAC, 2020b]. Across the Elizabeth River from NNSY are multiple private shipyards that fulfill a substantial portion of the surface combatant maintenance requirements for the USN. Across the Hampton Roads waterway is Newport News Shipbuilding, a private shipyard owned by Huntington Ingalls Industries. This facility spans 2.5 miles of waterfront along the James River, with four dry docks and over 550 acres. Newport News Shipbuilding is the only building and refueling yard for aircraft carriers, and one of two shipyards that construct submarines for the USN [Huntington Ingalls Industries, 2020]. Several other Department of Defense (DOD) facilities are spread throughout the Hampton Roads region to include Joint Base Langley-Eustis, Joint Expeditionary Base Little Creek-Fort Story, Naval Air Station Oceana, Naval Medical Center Portsmouth, Craney Island Fuel Depot, and Naval Support Activity Hampton Roads, which houses the NATO Allied Command Trans- formation, the only U.S. based NATO command [Hampton Roads Chamber, 2020]. This concentration of military related facilities in the greater Norfolk area makes safeguarding the region a vital priority with respect to the threat of sea level rise.

In addition to the DOD related facilities, the Port of Virginia has six terminals spanning 1,864 acres with 19,885 linear feet of berth space. The port is the deepest on the East Coast and the sixth largest container port in the United States [Virginia Port Authority, 2020]. The four facilities in the immediate Norfolk area are Norfolk International Terminal, Virginia International Gateway, Portsmouth Marine Terminal and Newport News Marine Terminal. Additionally, a port expansion has been approved for a marine terminal on Craney Island that would significantly ex- pand the container capacity [Virginia Port Authority, 2020]. Protecting these port facilities from the increased likelihood of flooding related to sea level rise, while also maintaining functionality, are two aspects that will be explored in this study. The locations of the major maritime facilities outlined above are shown in Figure 1-4

19 Figure 1-4: Hampton Roads and Major Maritime Facilities

Based on the concentration of maritime facilities and topography of Hampton Roads, the greater Norfolk, Virginia region was selected as the study area for this thesis. In regard to the major maritime installations, which include Naval Station Norfolk, Norfolk Naval Shipyard, Newport News Shipbuilding, the maintenance shipyards and the Port of Virginia terminals, failing to maintain the operational capacity of these facilities could have far reaching impacts ranging from national security to regional economic stability. With respect to topography, the vast majority of the greater Norfolk area has an elevation of less than 15ft in reference to the North American Vertical Datum of 1988 (NAVD88), and as a result, is susceptible to tidal flooding [USACE Norfolk District, 2018]. Figure 1-5 shows the shoreline heights for the City of Norfolk with 146 of 161 miles of shoreline within zero to five feet of present day sea level [Virginia Institute of Marine Science, 2020]. However, the general layout of the region, to include relatively narrow waterway access points, provides the possibility

20 of utilizing dynamic sea barriers to isolate waterways such as the Elizabeth or James Rivers from extreme tides or storm surges. The combination of the concentration of vital shoreline facilities, the regions susceptibility to tidal flooding, and topography of the local waterways establishes the greater Norfolk, VA area as a prime study location for a sea barrier design, feasibility and cost analysis.

Figure 1-5: Topographic Map of Norfolk, VA with Shoreline Elevations [Virginia Institute of Marine Science, 2020]

1.2 Sea Level Rise Trends and Projections

An analysis of the historical data pertaining to extreme water levels and sea level rise trends for Norfolk, VA, as shown in Figures 1-6 and 1-7, indicate a significant increase in LMSL, consistent with the nuisance flooding trend discussed in the previous section. As indicated in Figure 1-7, an analysis of sea level trend data from 1927 through 2019 is equivalent to a 1.54ft increase in LMSL over a 100 year period [NOAA, 2020c]. This increase in LMSL is nearly a foot higher than the global mean sea level (GMSL) rise since 1900 of 0.63ft [Sweet et al., 2017], indicating an accelerated risk for coastal flooding, and associated damage, in the Norfolk, Virginia region.

21 Figure 1-6: NOAA Extreme Water Levels for Norfolk, VA [NOAA, 2020c]

Figure 1-7: NOAA Sea Level Rise Trends for Norfolk, VA [NOAA, 2020c]

Based on these significant LMSL trends, Norfolk is consistently highlighted asan area of concern for sea level rise as shown in Figure 1-8. These spotlight reports are

22 helpful in highlighting the general issue, but conventionally provide only broad esti- mations, such as the 2.5ft to 11.5ft LMSL projection range listed in the introductory chapter of the Fourth National Climate Assessment, Volume II [Jay et al., 2018].

Figure 1-8: Sea Level Rise and Norfolk, VA [Jay et al., 2018, Kusnetz, 2018]

23 The LMSL trends, and broad range sea level rise projections, discussed above firmly establish that there is a significant risk for increased coastal flooding inthe Norfolk, VA area. However, these data points do not provide a specific sea level rise scenario that can be utilized for a design and feasibility analysis of sea barrier systems. As such, additional research was required to determine the most likely LMSL scenario for the year 2100 in Norfolk, VA. This sea level scenario would, in turn, be established as the LMSL design threshold for a conceptual sea barrier system. The primary documents referenced for this portion of the thesis were the 2016 SERDP Regional Sea Level Scenarios for Coastal Risk Management [Hall et al., 2016] and the 2017 Fourth National Climate Assessment, Volume I [Sweet et al., 2017]. A brief overview of some of the key findings from these reports is outlined below. The 2016 SERDP report provided an overview of the primary causes of global and regional sea level rise. Conceptualizing these large and small scale catalysts for sea level rise provides for a better understanding why a region such as Norfolk, VA may witness accelerated LMSL trends. The three primary causes of global sea level change are identified as thermal expansion, land-based ice melting, and land water storage changes as shown in Figure 1-9 [Hall et al., 2016].

Figure 1-9: Global Sea Level Rise Overview [Hall et al., 2016]

24 The National Climate Assessment outlines the same causes for global sea level rise with ice melting identified as the dominant factor (50%), followed by thermal expansion (37%) and land water storage (13%) [Sweet et al., 2017]. Figure 1-10 outlines the primary causes of local sea level changes, which are vertical land movement, ice melt effects, and dynamic sea level changes. The vertical land movement, also known as subsidence, and the effects of the ice melt, which alters the gravitational attraction associated with land masses, are cited as the primary causes for accelerated sea level rise in the Mid-Atlantic region near Norfolk, VA [Hall et al., 2016, Sweet et al., 2017].

Figure 1-10: Regional Sea Level Rise Overview [Hall et al., 2016]

The next aspect of the SERDP report that applied directly to this thesis was the description of different approaches to sea level rise estimation. These approaches were identified as deterministic, probabilistic, and scenario-based, as illustrated in Figure 1-11 [Hall et al., 2016]. This thesis will focus on establishing the most likely projection for the Norfolk, VA study area. Utilizing this scenario based approach, and focusing on the most likely projection, is in line with the recommendation of the 2017 NAVFAC Climate Change Installation Adaptation and Resilience Planning Hand- book [NAVFAC, 2017]. Referencing the SERDP report, the NAVFAC Handbook also states that considering less likely, but more conservative, scenarios is acceptable

25 for installations of high value and low risk tolerance. Additionally, the handbook recommends focusing on longer time periods, such as the year 2100, and considering less severe but more frequent storm events as design benchmarks [NAVFAC, 2017]. These SERDP and NAVFAC recommendations will be referenced when selecting the sea level rise projection and design threshold for the Norfolk, VA study area.

Figure 1-11: Sea Level Rise Projection Types [Hall et al., 2016]

Lastly, the SERDP report established five global sea level rise scenarios, ranging from 0.2m to 2.0m as shown in Figure 1-11 [Hall et al., 2016]. These GMSL projections were then tailored to individual DOD facilities based on regional trends, with the approximate projection range for the Norfolk, VA region being 2ft to 9ft by the year 2100 [Hall et al., 2016]. With reference to this model, the deterministic projection of the most likely scenario would indicate approximately a 5ft increase in LMSL for the Norfolk, VA study area. A similar set of sea level rise scenarios was provided in the National Climate Assessment. The only significant deviation from the SERDP report was the addition of a sixth scenario of a 2.5m global sea level rise based on extreme levels of ice melt [Sweet et al., 2017].

26 Figure 1-12: Sea Level Rise Scenario Curves [Hall et al., 2016]

Two central aspects of the sea level rise chapter of the Fourth National Climate Assessment, Volume I will be outlined below, to include the key findings of the report, and the sea level rise scenarios. The key findings of very high to high confidence from the National Climate Assessment are listed below [Sweet et al., 2017]:

• LMSL along portions of the East Coast and Gulf Coast are likely to be higher than the GMSL.

• LMSL rates are increasing in over 25 U.S. cities situated on the Atlantic Ocean and Gulf of Mexico. Based on this trend, tidal flooding will increase in breath, depth and frequency over the next century.

• LMSL rise will increase the frequency and scope of flooding associated with coastal storms such as a hurricane or nor’easter.

As previously discussed, the National Climate Assessment added an Extreme Sea Level Rise projection for a total of six scenarios as shown in Figure 1-13.

27 Figure 1-13: National Climate Assessment GMSL Scenarios Overview [Sweet et al., 2017]

As outlined in Figure 1-13, the sea level rise scenarios were compared to Ra- diative Concentration Pathways (RCP), which are atmospheric carbon concentration trajectories. The probabilities listed are the likelihood of GMSL exceeding the projection of a given sea level rise scenario based on the associated RCP. The orange box indicates the scenarios identified for this thesis as having acceptable de-

28 grees of risk associated with GMSL exceeding a scenario projection. On the other hand, the intermediate-low scenario is based on a 2050 stabilized global emissions rate. Based on this being an ambitious emissions forecast, and the presence of a lag between emission reductions and atmospheric concentrations decreasing, the risk of global sea levels exceeding the projections of this scenario are much higher [Sweet et al., 2017]. Based on this information, the intermediate sea level rise scenario was selected for this thesis as the most likely projection that also appropriately manages the associated risks of the study area. The decision to reference the intermediate sea level rise scenario aligns with the recommendation of the USNA Sea Level Rise Advisory Council which is using the same projection adjusted for Annapolis [USNA Sea Level Rise Advisory Council, 2019]. Based on the intermediate scenario, a 4.39ft sea level increase, in reference to NAVD88, is projected at the Sewells Point in Norfolk, VA [USACE, 2020]. Table 1.1 outlines the projected shift in water levels and the associated datums in Norfolk, VA between 2020 and 2100 in reference to NAVD88. Table 1.1: Norfolk, VA Tidal Datum Changes

Datum (Reference: NAVD88) 2020 Level (ft) 2100 Level (ft) NAVD88 0.00 0.00 MLLW -1.61 2.78 LMSL -0.25 4.14 MHHW 1.15 5.54 1-YR 2.59 6.98 10-YR 4.81 9.20 50-YR 6.15 10.54 100-YR 6.79 11.18

1.3 Mitigation Projects and Proposals

Over the course of this thesis, four studies were identified as having related objectives, to included flood barrier design, or the location of the study area. These included the U.S. Army Corps of Engineers (USACE) Norfolk Coastal Storm Risk Management

29 Study, the USACE New York-New Jersey Harbor and Tributaries Coastal Storm Risk Management Feasibility Study, the USACE Coastal Texas Protection and Restoration Feasibility Study and the Naval Facilities Engineering Command (NAVFAC) Mid- Atlantic NNSY Small Docks Flood Mitigation Study as shown in Figure 1-14.

Figure 1-14: Flood Management Feasibility and Mitigation Studies [USACE Norfolk District, 2018, NAVFAC MID-ATLANTIC, 2015, USACE Galveston District, 2018, USACE New York District, 2019]

30 An overview of these reports is outlined below, to include the key data points referenced for this thesis.

The USACE Norfolk Study conducted a design analysis of multiple flood barrier systems to mitigate coastal flooding in the City of Norfolk. The estimated costof the recommended solution is $1.6B (FY18), which includes barrier systems spanning Pretty Lake, the Lafayette River, the Hague and Broad Creek. Portions of these barriers are dynamic, in order to maintain tidal flow, as well as support the transit of small vessels. The largest of these dynamic structures is a 150ft wide sector gate across a shallow channel on the Lafayette River. Additionally, a seawall, constructed near the shoreline, protects the majority of downtown Norfolk. The average design height of the barrier system is 15.5ft above NAVD88, indicating that these structures can continue providing flood protection in 2100 for water levels up to 100 year storms, based on the projections shown in Table 1.1 [USACE Norfolk District, 2018]. Although the dynamic barrier system spanning the Lafayette River is complex and costly, it is likely more affordable and functional than installing shoreline barriers along the entire river. This design trade-off between a dynamic barrier, and shoreline infrastructure, is one of the central themes of this thesis, only on a larger scale. Overall, the proposals outlined in the Norfolk Study are an essential first step in protecting this region from coastal flooding. However, the study is limited in scope to the municipal boundaries of Norfolk, excluding surrounding cities, as well as federal and state facilities such as Naval Station Norfolk and Norfolk International Terminal. The study discusses eliminating the consideration of larger sea barrier systems, that would span waterways such as the Elizabeth River, because of the higher costs, and requirement for regional coordination [USACE Norfolk District, 2018]. This decision points to another theme of this thesis regarding the cost comparison of large sea barriers to regional shoreline barrier systems designed to protect equivalent areas.

The NAVFAC NNSY Study examines structural mitigation options to address the flood risks associated with the four smaller dry docks. As outlined in a2017Naval Shipyards Government Accountability Office (GAO) report, four of five dry docks are at risk of flooding, with three of the dry docks reaching a flood condition atthe

31 present day 10 year storm water levels. Additionally, portions of the shipyard experience one major flood event on average per year [GAO, 2017]. The NAVFAC report recommended a system of seawalls protecting dry docks two through four, which are the docks with the lowest risk tolerance based on the type of platforms maintained in these facilities. With substantial consideration to maintaining functionality around the dry docks, the seawall height was designed to a 500 year storm threshold at present day water levels. This equates to a barrier height of 10ft above NAVD88. Total project costs were projected at approximately $70M (FY15) [NAVFAC, 2017]. Expanding the scope of the seawall system, or raising the design height would have caused considerable disruptions to the functionality of the shipyard. However, based on the sea level projections discussed in the previous section, these proposed seawalls will likely be overtopped at 50 year storm water levels in the year 2100 as shown in Table 1.1. Overall, the mitigation proposals outlined in the NAVFAC NNSY report are an affordable solution to the near term flooding risks. However, additional flood barrier systems will be required to sufficiently protect the entire shipyard, based on sea level rise projections. The design decisions associated with balancing the installation of a flood barrier systems, with the requirement for maintaining the functionality of a shoreline facility, will be referenced throughout this thesis.

The USACE NY-NJ and TX studies have similar scales and design types. Both studies are in early stages, but provide invaluable design insights and cost data for this thesis. The NY-NJ Study is examining five design alternatives ranging from the exclusive use of shoreline barriers, stationed at the areas of greatest flooding risk, to a sea barrier system spanning the 6 mile wide harbor entrance from Sandy Hook to Breezy Point. This large scale sea barrier concept consists of 30 miles of structure, and an estimated construction cost of $36.5B (FY19) before contingency adjustments [USACE New York District, 2019]. In order to compare the wide range of alternatives in this study, the USACE New York District established a cost model for sea barriers that will be referenced throughout this thesis. The USACE TX study is similar in that it is also considering a range of options along the coastline. The most complex portion of the project focuses on the Houston Ship Channel near Galveston, TX.

32 At this location, the proposed barrier would include 70 miles of coastal structure to include a dynamic system spanning the 2.5 mile harbor entrance. This dynamic structure would include large environmental sluice gates to promote tidal flow, and a 1200ft wide sector gate across the 60ft deep channel. Early project cost estimates range from $23B to $32B (FY18) [USACE Galveston District, 2018]. The cost data from this report, as well as from a Gulf Coast Community Protection and Recovery District (GCCPRD) report that preceded the USACE TX Study [GCCPRD, 2018], was utilized to supplement the USACE NY-NJ Study cost model.

1.4 Thesis Contributions

The contributions of this thesis are twofold. First, this thesis conducted a design, feasibility and cost analysis of potential sea barrier systems for the greater Norfolk, Virginia area. The Norfolk area was selected as the study location because of its high risk to the impacts of sea level rise, the potential for the local topography to support the installation of a sea barrier system, and due to the regions vital importance to both the Commonwealth of Virginia and the federal government. With the substantial concentration of military facilities, shipyards and port terminals, storm surge related damages could have far reaching, and long standing impacts, ranging from disruptions to the regional economy and trade network, to significant risks to infrastructure and industries supporting national security. Harnessing the topography of the region, this study proposed six potential sea barrier systems with protection zones ranging in size from the entire Chesapeake Bay, to the Southern and Eastern Branches of the Elizabeth River. A feasibility study was conducted to determine if a sea barrier system, conventionally utilized for storm surge protection, could also be utilized to safeguard shorelines from high tide flooding. The feasibility criteria was straightforward: if substantial flooding was projected at low tide or mean sea level, based on an intermediate sea level rise scenario in the year 2100, then a sea barrier system alone, could not be used to safeguard the Norfolk, VA region. However, if minimal flooding was projected at these lower water levels, it

33 was established that a sea barrier system could potentially replace the requirement for extensive shoreline barrier infrastructure. In order to examine the six sea barrier concepts, an Overall Measure of Effectiveness (OMOE) analysis was conducted with performance criteria ranging from the scale and associated protection area of the design concept, to the maritime traffic and environmental impacts of the proposed sea barrier system. A cost analysis was then conducted on all six design concepts utilizing a storm surge barrier cost model developed by the USACE New York District in 2019 as part of the NY-NJ Harbor and Tributaries Coastal Storm Risk Management Feasibility Study [USACE New York District, 2019]. This cost model was analyzed with respect to other ongoing USACE studies for Norfolk, VA and the Texas Gulf Coast to establish the consistency of the formula in estimating construction cost of sea barrier systems. With the OMOE and cost analyses completed, a cost versus performance plot was created to determine the optimal sea barrier concept design for the greater Norfolk, VA area. The second aspect of the thesis was a comparative cost analysis of the recommended sea barrier design, to the alternative option of a shoreline barrier system that provided equivalent protection. Shoreline barriers were separated into two categories for the cost analysis, shore based infrastructure, and a hybrid shoreline barrier system incorporating shore based infrastructure and shallow water dynamic barriers. Both types of shoreline barriers were analyzed to determine a notional cost that could be compared to the sea barrier system selected as the optimal concept. In total, this thesis provided a notional sea barrier design, selected as the optimal concept from six designs, with the ability to safeguard a region with vital coastal facilities and industries from the ever increasing risks associated with sea level rise. Additionally, this thesis provided a cost comparison of a sea barrier system to equivalent shoreline infrastructure, with the goal of determining the most cost effective approach for protecting an expansive estuary. Although every location requires different design considerations, the comparison of these two large scale coastal flood protection approaches provided some relevant conclusions for future coastal protection design studies.

34 Chapter 2

Sea Barrier Feasibility Analysis

Determining the notional feasibility of a sea barrier system for the Norfolk, Virginia region required an analysis of the projected rise in sea levels, and the associated impacts to coastal properties, to include several major maritime facilities. This baseline feasibility analysis had two objectives. First, the analysis created a comparative illustration of the impacts of sea level rise over a range of elevated tides to include mean higher high water (MHHW) and storm surge conditions. This part of the analysis provided the illustrative data necessary to determine if a large scale sea barrier system was practical and warranted based on local topography, and the projected sea levels in the year 2100. Second, the analysis provided important insights into coastal conditions, and the associated functionality of coastal facilities, at lower tidal levels ranging from mean lower low water (MLLW) to mean sea level (MSL). A dynamic sea barrier designed to be activated during elevated tide levels would be impractical if significant coastal flooding was already occurring during low tide or at mean sealevel. In the case of extensive low tide flooding, a robust network of shoreline seawalls and infrastructure elevation would be the only viable solution, short of facility relocation.

2.1 Study Locations

As part of the feasibility analysis, Naval Station Norfolk and Norfolk Naval Shipyard were selected as study locations within the greater Norfolk, Virginia study area. These

35 two naval installations were chosen because of their important roles as large scale shoreline facilities and due to their varying locations within the study area. Naval Station Norfolk, located at Sewells Point near the mouth of the James and Elizabeth Rivers, is the largest coastal naval base in the world with over eight miles of shoreline and 4631 acres. The base houses an airfield and an extensive port facility with 11 miles of pier and wharf space [NAVFAC, 2020a, CNIC, 2020]. Figure 2-1 shows an aerial view and a boundary map of the base, as well as the location of Naval Station Norfolk relative to the greater Norfolk, Virginia region.

Figure 2-1: Study Location One (Naval Station Norfolk) [CNIC, 2020, NAVFAC, 2020a]

36 Norfolk Naval Shipyard (NNSY) is located in Portsmouth, Virginia on the southern branch of the Elizabeth River. Serving as the primary East Coast maintenance yard for aircraft carriers and a large percentage of submarines, the shipyard fills an invaluable role. NNSY has four miles of shoreline wharf and over 800 acres between the main facility and nearby annexes [NAVFAC, 2020b]. NNSY was selected as the second study location due to its inland location, 10 miles upriver from Naval Station Norfolk. Figure 2-2 shows shows an aerial view and a boundary map of the shipyard, as well as the location of NNSY relative to the greater Norfolk, Virginia region.

Figure 2-2: Study Location Two (Norfolk Naval Shipyard) [National Archives, 1995, NAVFAC, 2020b]

37 2.2 Tidal Data and Sea Level Projections

An analysis of projected sea levels was conducted for Naval Station Norfolk and Nor- folk Naval Shipyard utilizing a joint USACE and National Oceanic and Atmospheric Administration (NOAA) database [USACE, 2020]. The database provided tidal datums, extreme water levels and sea level rise projections for the NOAA measurement stations within the boundaries of both naval facilities. Figures 2-3 and 2-4 show the tidal datums and extreme water levels for Naval Station Norfolk (Sewells Point) and Norfolk Naval Shipyard respectively [USACE, 2020].

Figure 2-3: Naval Station Norfolk Tidal and Extreme Water Data

Figure 2-4: Norfolk Naval Shipyard Tidal and Extreme Water Data

38 Utilizing the same USACE and NOAA database, sea level projections were ac- cessed for both study locations. Figures 2-5 and 2-6 show the sea level projections through the year 2100 in reference to local mean sea level (LMSL) with the intermediate scenario selected for Naval Station Norfolk (Sewells Point) and Norfolk Naval Shipyard respectively [USACE, 2020].

Figure 2-5: Naval Station Norfolk Sea Level Projections

Figure 2-6: Norfolk Naval Shipyard Sea Level Projections

NOAA intermediate projections indicate a rise in LMSL of 4.65ft and 4.59ft for Naval Station Norfolk and Norfolk Naval Shipyard respectively by the year 2100.

39 Tables 2.1 and 2.2 compare present day (YR 2020) tidal data to projected (YR 2100) sea levels in reference to year 2020 LMSL.

Table 2.1: Naval Station Norfolk 2020 and 2100 Tidal Data Comparison

Datum (Units: FT, Reference: 2020 LMSL) YR 2020 YR 2100 North American Vertical Datum 1988 (NAVD88) 0.26 0.26 Mean Lower Low Water (MLLW) -1.35 3.30 Local Mean Sea Level (LMSL) 0.00 4.65 Mean Higher High Water (MHHW) 1.40 6.05 Annual Storm (1-YR) 2.85 7.50 Ten Year Storm (10-YR) 5.07 9.72 Hundred Year Storm (100-YR) 7.05 11.70

Table 2.2: Norfolk Naval Shipyard 2020 and 2100 Tidal Data Comparison

Datum (Units: FT, Reference: 2020 LMSL) YR 2020 YR 2100 North American Vertical Datum 1988 (NAVD88) 0.27 0.27 Mean Lower Low Water (MLLW) -1.52 3.07 Local Mean Sea Level (LMSL) 0.00 4.59 Mean Higher High Water (MHHW) 1.58 6.17 Annual Storm (1-YR) 3.06 7.65 Ten Year Storm (10-YR) 5.24 9.83 Hundred Year Storm (100-YR) 6.94 11.53

The sea level projections for Naval Station Norfolk and Norfolk Naval Shipyard were converted to reference year 2020 MHHW as outlined in Table 2.3. The average of both study locations was calculated for each datum, and rounded to the nearest one-foot interval as shown in Table 2.4. The sea level projections were converted to MHHW and rounded to the nearest foot in preparation for plotting the data in the NOAA Sea Level Rise Viewer [NOAA, 2020a]. A snapshot of the viewer, with the intermediate scenario selected for the year 2100, is shown in Figure 2-7. The viewer plots direct flooding, from seawater flowing over a shoreline, in light blue. Light green denotes low lying areas with a high probability of indirect flooding due to rainwater or seawater pooling as a result of tidal interactions with gravity drainage systems.

40 Table 2.3: Projected Tidal Data Above Year 2020 MHHW

Datum (FT +/- YR 2020 MHHW) Naval Station Naval Shipyard NAVD88 -1.14 -1.31 MLLW 1.90 1.49 LMSL 3.25 3.01 MHHW 4.65 4.59 1-YR 6.10 6.07 10-YR 8.32 8.25 100-YR 10.30 9.95

Table 2.4: Norfolk, VA Tidal Projections Above Year 2020 MHHW

Datum (FT +/- YR 2020 MHHW) Average Value Rounded Value NAVD88 -1.23 -1.0 MLLW 1.70 2.0 LMSL 3.13 3.0 MHHW 4.62 5.0 1-YR 6.09 6.0 10-YR 8.29 8.0 100-YR 10.13 10.0

Figure 2-7: NOAA Sea Level Rise Viewer

41 2.3 High Water Analysis

As stated at the beginning of this chapter, the first objective of the feasibility analysis was to examine the study locations at elevated tidal values to include MHHW and storm conditions. This portion of the analysis provided a visualization of the impacts each of the high water levels would have on Naval Station Norfolk and Norfolk Naval Shipyard. In turn, the illustrative data assisted in determining if a large scale sea barrier system was warranted and practical. MHHW and water levels for an annual, ten year and one hundred year storm were plotted in the NOAA Sea Level Rise Viewer [NOAA, 2020a] for both naval facilities. Water levels were plotted in one-foot intervals above year 2020 MHHW as listed in Table 2.4.

2.3.1 Naval Station Norfolk Projected High Water Analysis

Figure 2-8: Naval Station Norfolk MHHW Tidal Projection (Year 2100)

MHHW: 5ft above YR 2020 MHHW. Minor direct flooding occurred at four locations along the northern waterfront of the base. The potential for indirect flooding was significant, but mostly contained to areas nonessential to base operations.

42 Figure 2-9: Naval Station Norfolk 1-YR Storm Projection (Year 2100)

1-YR Storm: 6ft above YR 2020 MHHW. Direct flooding increased significantly to include an aircraft taxiway, roads, parking lots and a handful of buildings.

Figure 2-10: Naval Station Norfolk 10-YR Storm Projection (Year 2100)

10-YR Storm: 8ft above YR 2020 MHHW. Substantial direct flooding with upwards of 40 percent of the base nonoperational to include access to all warship berths.

43 Figure 2-11: Naval Station Norfolk 100-YR Storm Projection (Year 2100)

100-YR Storm: 10ft above YR 2020 MHHW. Debilitating direct flooding with over 75 percent of the base damaged and inaccessible. The analysis of the effects of projected high water levels on Naval Station Norfolk indicated varied results ranging from minor nuisance flooding at MHHW to extreme base-wide flooding at the 100-YR storm levels. Overall, the high water analysis illustrated the need for large scale mitigating infrastructure such as a sea barrier to preserve the facilities and functionality of Naval Station Norfolk through storm surge conditions in the year 2100. Even the projected annual storm surge conditions of 6ft would cause disruptive flooding to the base on par with the year 2020 100-YR storm surge levels of 5.65ft above MHHW or 7.05ft above LMSL.

2.3.2 Norfolk Naval Shipyard Projected High Water Analysis

The high water analysis for Norfolk Naval Shipyard was completed in the same man- ner as Naval Station Norfolk with an analysis of projected MHHW, 1-YR, 10-YR, and 100-YR water levels in the year 2100. With the location of the shipyard 10 miles upriver from the naval station, the analysis provided a secondary snapshot of projected impacts within the greater Norfolk, Virginia study area.

44 Figure 2-12: Norfolk Naval Shipyard MHHW Tidal Projection (Year 2100)

MHHW: 5ft above YR 2020 MHHW. Significant flooding to a portion of the shipyard.

Figure 2-13: Norfolk Naval Shipyard 1-YR Storm Projection (Year 2100)

1-YR: 6ft above YR 2020 MHHW. Substantial flooding to most of the shipyard.

45 Figure 2-14: Norfolk Naval Shipyard 10-YR Storm Projection (Year 2100)

10-YR: 8ft above YR 2020 MHHW. Extensive flooding of the entire shipyard.

Figure 2-15: Norfolk Naval Shipyard 100-YR Storm Projection (Year 2100)

100-YR: 10ft above YR 2020 MHHW. Debilitating flooding of the entire shipyard.

46 The analysis of the impacts of projected high water levels on Norfolk Naval Ship- yard also illustrated varied results, but were more severe at MHHW and the 1-YR storm levels as compared to the impacts experienced at Norfolk Naval Station. Over- all, the high water analysis of Norfolk Naval Shipyard also illustrated the need for large scale mitigating infrastructure such as a sea barrier to preserve the facilities and functionality of the naval shipyard. However, the need for tidal flood protection upriver near Norfolk Naval Shipyard is even greater than that of Norfolk Naval Sta- tion because of the potential for daily flooding conditions brought about by MHHW levels. This projection will drive the design and analysis phase of this project in two ways. First, a shore based barrier system would require extensive infrastructure lining the entire bank of the Elizabeth River in low-lying areas to prevent the flanking of seawalls. Second, a sea gate at the mouth of the Elizabeth River, in the vicinity of Naval Station Norfolk, would be required to close up to twice daily due to the high tide flooding projections near the shipyard. In contrast, a sea gate only functioning to protect Naval Station Norfolk may only need to close during a King Tide, and during storm surge conditions.

2.4 Low Water and Mean Sea Level Analysis

The second objective of the feasibility analysis was to analyze the study locations at low tide and mean sea level in order to determine the condition of coastal facilities at these lower water levels. A dynamic sea barrier designed to be activated during elevated water levels would be impractical if significant coastal flooding also occurred during low tide or at mean sea level. MLLW and LMSL were plotted in the NOAA Sea Level Rise Viewer for both naval facilities [NOAA, 2020a]. Water levels were plotted in one-foot intervals above year 2020 MHHW as listed in Table 2.4. Figures 2-16-2-19 indicate that although the MLLW and LMSL water levels are projected to be much higher in 2100 as compared to the year 2020, the ongoing design studies for shoreline infrastructure improvements near downtown Norfolk and at Norfolk Naval Shipyard will be sufficient to prevent coastal flooding at the lower water levels.

47 2.4.1 Naval Station Norfolk Projected Low Water Analysis

Figure 2-16: Naval Station Norfolk MLLW Tidal Projection (Year 2100)

Figure 2-17: Naval Station Norfolk LMSL Tidal Projection (Year 2100)

48 2.4.2 Norfolk Naval Shipyard Projected Low Water Analysis

Figure 2-18: Norfolk Naval Shipyard MLLW Tidal Projection (Year 2100)

Figure 2-19: Norfolk Naval Shipyard LMSL Tidal Projection (Year 2100)

49 2.5 Norfolk, VA Storm Flooding Comparison

Figure 2-20: Norfolk, VA Study Area Storm Surge Flooding Comparison

50 Chapter 3

Sea Barrier Concept Designs

Six sea barrier concept designs were created to protect varying areas of the Chesapeake Bay and tributaries surrounding the greater Norfolk, Virginia study area. Each design included up to three different barrier types within the overall system to include static, auxiliary dynamic and navigable dynamic structures. The static portions of the sea barrier designs consist of seawalls that tie the system into high ground on shore, or span between dynamic sections of the system. The auxiliary dynamic sections of the system are designed to promote increased water flow through the barrier when the sea barrier system is open in order to minimize the environmental impacts associated with the movement of nutrients, sediment and sea life. The auxiliary dynamic sections utilize a series of miter or sluice gates to support water flow and can also serve as auxiliary passageways for small pleasure craft. The last barrier type is the navigable dynamic section of the system. This section consists of large sector gates that close to seal off the deep water navigation channels when the sea barrier system is activated. These three categories of sea barrier are exhibited in two concept designs from the preliminary USACE New York-New Jersey Harbor and Tributaries Feasibility Study [USACE New York District, 2019]. The Arthur Kill Barrier concept shown in Figure 3-1 has a central navigable section (labeled as B). This navigable section includes a sector gate which close to seal off the main channel, and the two artificial islands created to stow the sector gate arms when the barrier system is open. The navigable dynamic section is flanked by two smaller

51 auxiliary dynamic sections (labeled as A and C). These auxiliary sections have one sluice gate each which allow for additional water flow through the open sea barrier system, and function as auxiliary passageways for smaller vessels. The remainder of the sea barrier system is comprised of static seawalls spanning from the dynamic sections to high ground on both shorelines [USACE New York District, 2019].

Figure 3-1: Arthur Kill Barrier Concept in the Greater New York City Area [USACE New York District, 2019]

The Jamaica Bay Barrier concept shown in Figure 3-2 has a central navigable section (labeled as D). This navigable section includes two sector gates, and the associated stowage areas, which close to seal off an inbound and outbound chan-

52 nel. The navigable dynamic section is flanked by a series of sluice gates on both sides which form the auxiliary dynamic sections (labeled as A, B, C and E). The 15 sluice gates, which span the vast majority of the waterway, significantly increase the rate of water flow through the barrier system, and subsequently decrease the environmental impacts. The outermost sections of the sea barrier are comprised of static seawalls that serve as tie-ins from the dynamic sections to high ground [USACE New York District, 2019].

Figure 3-2: Jamaica Bay Barrier Concept in the Greater New York City Area [USACE New York District, 2019]

53 3.1 Sea Barrier Concept Design One

Sea Barrier One is located near the mouth of the Chesapeake Bay, and parallel to the Chesapeake Bay Bridge-Tunnel. This design concept consists of approximately 18.5 total miles of sea barrier structure, to include 10 miles of static seawall, 7.25 miles of auxiliary dynamic and 1.25 miles of navigable dynamic. Figures 3-3 and 3-4 illustrate the the design overlaid on a nautical chart and satellite image.

Figure 3-3: Sea Barrier Concept Design One Chart View

54 Figure 3-4: Sea Barrier Concept Design One Satellite View

55 3.2 Sea Barrier Concept Design Two

Sea Barrier Two is located at the confluence of the James and Elizabeth Rivers, and parallel to the existing Hampton Roads Bridge-Tunnel. This design consists of approximately 4.5 miles of sea barrier structure, to include 2.5 miles of static seawall, 1.5 miles of auxiliary dynamic and 0.5 miles of navigable dynamic. Figures 3-5 and 3-6 illustrate the the design overlaid on a nautical chart and satellite image.

Figure 3-5: Sea Barrier Concept Design Two Chart View

56 Figure 3-6: Sea Barrier Concept Design Two Satellite View

57 3.3 Sea Barrier Concept Design Three

Sea Barrier Three is located near the mouth of the Elizabeth River in the vicinity of Willoughby Bay and Naval Station Norfolk. This design consists of approximately 5.5 miles of sea barrier structure, to include 2.75 miles of static seawall, 2.25 miles of auxiliary dynamic and 0.5 miles of navigable dynamic. Figures 3-7 and 3-8 illustrate the the design overlaid on a nautical chart and satellite image.

Figure 3-7: Sea Barrier Concept Design Three Chart View

58 Figure 3-8: Sea Barrier Concept Design Three Satellite View

59 3.4 Sea Barrier Design Four

Sea Barrier Four is located near Pinner Point and parallel to the Elizabeth River Tunnel. This design consists of approximately 0.5 miles of sea barrier structure with 0.3 miles of static seawall and a 0.2 mile navigable dynamic section. Figures 3-9 and 3-10 illustrate the the design proposal overlaid on a nautical chart and satellite image.

Figure 3-9: Sea Barrier Concept Design Four Chart View

Figure 3-10: Sea Barrier Concept Design Four Satellite View

60 3.5 Sea Barrier Design Five

Sea Barrier Five incorporates the designs concepts of Sea Barriers Two and Four. Figure 3-11 shows the combined design proposal superimposed on a satellite image.

Figure 3-11: Sea Barrier Concept Design Five Satellite View

61 3.6 Sea Barrier Design Six

Sea Barrier Six incorporates the designs concepts of Sea Barriers Three and Four. Figure 3-12 shows the combined design proposal superimposed on a satellite image.

Figure 3-12: Sea Barrier Concept Design Six Satellite View

62 Chapter 4

Sea Barrier Performance Analysis

Following the development of the six sea barrier concepts, an overall measure of effectiveness (OMOE) was conducted to analyze the performance of each design. The following OMOE performance categories were established to evaluate the design concepts: Project Scale, Protection Area, Perimeter Flooding, Frequency of Operation, Maritime Traffic Impact and Environmental Impact. A figure of merit (FOM), ranging from one to five, was assigned to each sea barrier concept for every performance category, with one being a low score and five being a high score. A description, and the associated weight factor, of each evaluation category is discussed below:

• Project Scale: The Maeslantkering and Eastern Scheldt surge barriers, both part of the Delta Works, were utilized as reference scales. Although both projects have been operational for over two decades, with Maeslantkering completed in 1997 and Eastern Scheldt in 1986, these barrier systems remain benchmark designs. Concept designs that were larger in scale than the reference projects received a lower FOM due to increased cost and complexity, while proposals that were on par or smaller in scale were assigned a higher FOM. Figure 4-1 depicts the navigable dynamic Maeslantkering sector gate which protects the 0.25 mile wide Port of Rotterdam channel. Figure 4-2 shows the Eastern Scheldt Surge Barrier which is a combination static seawall and auxiliary dynamic sluice gate system spanning five miles across an estuary [Watersnood Museum, 2020].

63 Figure 4-1: Delta Works: Maeslantkering Sector Gate [Higgins, 2012, Watersnood Museum, 2020]

Figure 4-2: Delta Works: Eastern Scheldt Surge Barrier [Watersnood Museum, 2020]

64 • Protection Area: Design proposals were evaluated based on the size and characteristics of the protection area situated behind the sea barrier. Protection area characteristics included the quantity of shoreline, and the number of large facilities vulnerable to coastal flooding such as DOD installations, shipyards and port terminals.

• Perimeter Flooding: As part of the feasibility analysis conducted in Chapter 2, several high water scenarios were analyzed to determine the extent of coastal flooding in the Norfolk, Virginia region. The most extreme of these scenarios was a 100 year storm in the year 2100 with a projected high water level of 10ft above present day MHHW. Each design concept was evaluated under this extreme condition to determine if flooding breached the desired perimeter established by the sea barrier due to flanking as a result of local topography. Examples of perimeter flooding include a storm surge advancing across lowly- ing areas from the Virginia Beach coastline, or flood waters backing-up into the region from waterways leading from North Carolina such as the Dismal Swamp Canal. Design concepts that had minimal perimeter flooding received a higher FOM. Conversely, design proposals that required several additional barrier projects to prevent perimeter flooding were assigned a lower FOM. Shoreline infrastructure proposed in ongoing design studies such as the USACE Norfolk Study will be factored into the assigned FOM as a planned mitigation.

• Frequency of Operation: The frequency of operation of a design proposal was evaluated based on a projected five foot increase in MHHW by the year 2100 as outlined in Chapter 2. If significant flooding was indicated on the NOAA sea level rise viewer at MHHW based on present day land elevations and shoreline infrastructure, it was assumed that the proposed sea barrier would be activated to prevent the flooding. Design proposals that required high frequencies of operation to prevent flooding during daily high tides received a lower FOM. Design concepts that only required activation during elevated water levels such as a spring tide or annual storm were assigned a higher FOM.

65 • Maritime Traffic Impact: The locations associated with the design concepts affect varying densities of maritime traffic flow within the Chesapeake Bayand its tributaries. If a proposed sea barrier design was activated and closed due to elevated water levels, it was considered for this analysis that the Atlantic Ocean was inaccessible to inbound and outbound traffic. The inclusion ofa lock system, to allow for continued traffic flow throughout a sea barrier closure period, could mitigate the traffic flow issue, but was not considered during this portion of the performance analysis. In this case, design proposals that impacted higher densities of maritime traffic received a lower FOM.

• Environmental Impact: Estuaries like the Chesapeake Bay, and the associated tidal tributaries, are dependent on the tide cycle to provide nutrient flows. Altering these environmental processes with the closure of a sea barrier, or merely the presence of the static portions of the structures, will alter water, sediment and nutrient flows throughout an estuary such as the Chesapeake Bay. For these reasons, design proposals with the largest environmental impact areas were assigned a lower FOM. In contrast, relatively small impact areas received a higher FOM.

Table 4.1 indicates the weight factor applied to each of the evaluation categories:

Table 4.1: OMOE Performance Category Weight Factors

OMOE Performance Category Weight Factor Project Scale 0.25 Protection Area 0.25 Perimeter Flooding 0.20 Frequency of Operation 0.10 Maritime Traffic Impact 0.10 Environmental Impact 0.10

The project scale, protection area and ability to prevent perimeter flooding were assigned the highest weight factors due to their direct association with the construction cost, as well as the potential cost benefit of the proposal.

66 4.1 OMOE: Project Scale Analysis

The navigable, auxiliary and static components of each concept design were compared to the Delta Works reference projects to quantify the scale of the proposed design.

Table 4.2: Navigable Section Comparison

Design Gates Gate (mi) Stowage (mi) Total (mi) Comparison Reference 1 0.24 0.26 0.50 - One 2 0.24/0.35 0.13/0.20 1.25 150% Two 1 0.24 0.26 0.50 0% Three 1 0.24 0.26 0.50 0% Four 1 0.10 0.10 0.20 -60% Five 2 0.24/0.10 0.13/0.10 0.70 40% Six 2 0.24/0.10 0.13/0.10 0.70 40%

Table 4.2 compares the number of gates, gate length, gate stowage area length, total length (gate lengths plus the stowage area lengths) and the percent difference of the total navigable length of the reference project and the concept designs.

Table 4.3: Auxiliary Section Comparison

Design Sections Total (mi) Comparison Reference 3 2.00 - One 8 7.30 265% Two 3 1.50 -25% Three 3 2.25 13% Four 0 0.00 -100% Five 3 1.50 -25% Six 3 2.25 13%

67 Table 4.3 compares the number of auxiliary sections, total auxiliary length and the percent difference of the total auxiliary length of the reference and concept designs.

Table 4.4: Static Section Comparison

Design Sections Total (mi) Comparison Reference 5 3.00 - One 11 10.05 235% Two 4 2.40 -20% Three 5 2.80 -7% Four 2 0.35 -88% Five 6 2.75 -8% Six 7 3.15 5%

Table 4.4 compares the number of static sections, total static length and the percent difference of the total static length of the reference and concept designs.

Table 4.5: FOM: Project Scale

Concept Total Project Scale Assigned Figure Design Length (mi) Comparison of Merit (FOM) Reference 5.50 - - One 18.60 238% 1.0 Two 4.40 -20% 4.5 Three 5.55 1% 3.0 Four 0.55 -90% 5.0 Five 4.95 -10% 4.0 Six 6.10 11% 2.0

Table 4.4 lists the total length of each design, the percent difference of the total length of the reference and concept designs, and the assigned FOM for each of the concept designs based on project scale. Concept Design Four received the highest FOM due to its smaller scale compared to the reference project.

68 4.2 OMOE: Protection Area Analysis

The design concept protection areas were analyzed and compared. Table 4.6 outlines the body of water and estimated length of tidal shoreline protected by each design [Virginia Institute of Marine Science, 2020]. Figure of merits were assigned based on the relative size of the protection area, with Design One receiving the highest FOM and Design Four receiving the lowest FOM. Figure 4-3 shows the Chesapeake Bay DOD installations with Design One protecting the largest number of facilities followed by Concepts Two and Five, Concepts Three and Six, and Concept Four respectively. Table 4.6: FOM: Protection Area

Design Shoreline (mi) Body of Water FOM One 11684 Chesapeake Bay & Tributaries 5.0 Two 2306 James & Elizabeth Rivers 4.0 Three 458 Elizabeth River (3 Branches) 3.0 Four 268 Elizabeth River (2 Branches) 1.0 Five 2306 James & Elizabeth Rivers 4.0 Six 458 Elizabeth River (3 Branches) 3.0

Figure 4-3: Chesapeake Bay Region DOD Installations [USGS, 2020]

69 4.3 OMOE: Perimeter Flooding Analysis

Each of the design concepts was analyzed to determine the potential for perimeter flooding. Figure 4-4 shows the four baseline sea barrier designs with 100 year storm surge conditions in the year 2100. Color coded boxes outline the areas of concern for perimeter flooding.

The green box indicates an area of low concern for Design Concept Two, Three, Five and Six with potential flooding across Willoughby Spit. This area is color coded green to indicate that a current USACE project proposal will address this area of flooding potential [USACE Norfolk District, 2018].

The yellow boxes indicate areas of moderate concern for Design Concept One and Two. These perimeter flooding areas can be mitigated by increasing the length ofthe sea barrier tie-ins to areas of higher ground. These extended tie-ins can be installed with minimal increases to project cost or scale.

The red boxes indicate areas of high concern for perimeter flooding. The two red boxes closest to the bottom of the figure outline the Dismal Swamp Canal and the Albemarle and Chesapeake Canal. Both canals are part of the Intracoastal Water- way, a system of inland waterways from Texas through New England. The Dismal Swamp Canal runs along the boundary to the Great Dismal Swamp, and eventually to an estuary in North Carolina. The Albemarle and Chesapeake Canal connects the Elizabeth River to the coastal region near Virginia Beach. Both of these canals already have locks installed to regulate present day tidal fluctuations. However, locks of increased height, with shore tie-ins to high ground, will likely need to be installed to prevent year 2100 tidal surges from backing-up into the Norfolk, Virginia area from North Carolina and Virginia Beach. These two areas of perimeter flooding affect all six design concepts. The third red box is centered on Design Concept Four which ex- periences extensive perimeter flooding at water levels above year 2100 annual storms. Although Design Concepts Five and Six incorporate Sea Barrier Four in the overall designs, the addition of the larger sea barriers near the mouth of the Elizabeth River mitigates the perimeter flooding risk of 10 and 100 year storms.

70 Figure 4-4: Areas of Probable Perimeter Flooding

Table 4.7: FOM: Perimeter Flooding

Design Sources of Perimeter Flooding FOM One Intracoastal Canals & Shore Tie-Ins 3.0 Two Intracoastal Canals & Shore Tie-Ins 3.0 Three Intracoastal Canals 4.0 Four Intracoastal Canals & Storm Surges 1.0 Five Intracoastal Canals & Shore Tie-Ins 3.0 Six Intracoastal Canals 4.0

Table 4.7 outlines the perimeter flooding sources and the assigned figure of merits for each design concept. Designs Three and Six received the highest FOM, while Design Four was assigned the lowest FOM due to storm surge perimeter flooding.

71 4.4 OMOE: Frequency of Operation Analysis

The frequency of operation of the sea barrier design concepts is dependent on the local tidal cycles. Although the tides in the northern bay near Baltimore are mixed, the tides at the mouth of the Chesapeake Bay are semi-diurnal as shown in Table 4-5.

Figure 4-5: Mouth of the Chesapeake Bay Tides (01-31JAN2020) [NOAA, 2020c]

As a result of the semi-diurnal tides at the mouth of the Chesapeake Bay, the sea barriers would need to be activated up to twice daily to prevent high tide flooding based on the MHHW projections for the year 2100. Although some neap tidal cycles may not require daily closures, spring tides will likely require twice daily operations. For this analysis, a twice daily closure will be utilized as the baseline requirement.

Table 4.8: FOM: Frequency of Operation

Design Closure Pattern FOM One All Gates Twice Daily 2.0 Two All Gates Twice Daily 2.0 Three All Gates Twice Daily 2.0 Four All Gates Twice Daily 2.0 Five Inner Gate Twice Daily 4.0 Six Inner Gate Twice Daily 4.0

72 4.5 OMOE: Maritime Traffic Impact Analysis

The Chesapeake Bay is a major hub for commercial and naval maritime traffic to include the Port of Virginia, the Port of Baltimore (POB) and several USN related facilities. The Port of Virginia includes the following facilities: Norfolk International Terminal (NIT), Portsmouth Marine Terminal (PMT), Virginia International Gate- way (VIG), Newport News Marine Terminal (NNMT) and Richmond Marine Ter- minal (RMT) [Virginia Port Authority, 2020]. USN related facilities include Naval Station Norfolk (NSN), Norfolk Naval Shipyard (NNSY), Newport News Shipbuild- ing (NNSB), Craney Island Fuel Depot (CI) and several Elizabeth River Maintenance Yards (ERMY). The Elizabeth River also hosts several other industrial and petroleum storage facilities, as well as the connection of the intracoastal waterways to the Chesa- peake Bay. In the event of a twice daily high tide closure of the sea barriers (SB), Table 4.9 outlines marine traffic disruptions to and from these facilities.

Table 4.9: FOM: Maritime Traffic Impact

Port Facility SB1 SB2 SB3 SB Four SB Five SB Six Port: POB X Port: RMT X X Port: NNMT X X Port: NIT X X X Port: VIG X X X Port: PMT X X X Port: CI X X X Port: ERF X X X X X X Navy: NSN X X X Navy: NNSY X X X X X X Navy: NNSB X X Navy: ERMY X X X X X X

73 Figure 4-6: Norfolk, Virginia Port Facilities

Figure 4-6 shows the major commercial (blue) and USN related facilities (red) in the greater Norfolk region. Yellow lines outline the sea barrier concept locations. Table 4.10 outlines the impacted port facilities and the assigned figure of merits for each of the sea barrier design concepts.

Table 4.10: FOM: Maritime Traffic Impact

Design Impacted Port Facilities FOM One 12 of 12 1.0 Two 11 of 12 2.0 Three 8 of 12 3.0 Four 3 of 12 4.0 Five 3 of 12 4.0 Six 3 of 12 4.0

74 4.6 OMOE: Environmental Impact Analysis

Figure 4-7: Environmental Impact Areas [Virginia Institute of Marine Science, 2020]

75 The environmental impact was quantified by the surface area of the waterways associated with each of the design concepts. Figure 4-7 illustrates the variation in size of the environmental impact areas associated with the four baseline designs. As hybrid designs, Concepts Five and Six were not depicted because the environmental impact is mitigated with the decreased frequency of operation of the outer gates. An inverse relationship was noted in the figure of merits assigned to the design concepts forthe environmental impact analysis and the protection area analysis. Large protection areas received a lower score in this case because of the increased scope of the environmental impacts over the larger areas. Table 4.11 outlines the figures of merit assigned to each of the design concepts for the environmental impact analysis.

Table 4.11: FOM: Environmental Impact

Design Impacted Body of Water FOM One Chesapeake Bay & Tributaries 1.0 Two James, Elizabeth & Lafayette Rivers 2.5 Three Elizabeth & Lafayette Rivers 3.5 Four Elizabeth River (Southern & Eastern Branches) 5.0 Five Hybrid Impact: Designs Two & Four 4.0 Six Hybrid Impact: Designs Three & Five 4.5

4.7 OMOE Results

Figures 4-8, 4-9 and 4-10 outline the results of the overall measure of effectiveness (OMOE) analysis of the six design concepts. A comparison of the weighted sums of the figure of merits indicated that Design Concept Five, which is a combination of Designs Two and Four as shown in Figure 4-11, is the most effective design based on the performance criteria analyzed in this chapter. In the next chapter, a cost analysis will be completed for each of the design concepts in order to develop a cost vs performance plot to determine if Design Concept Five remains the optimal design.

76 Figure 4-8: OMOE Results Table

Figure 4-9: FOM Comparison Graph

Figure 4-10: Weighted Sum Comparison Graph

77 Figure 4-11: Sea Barrier Concept Five Overview

Table 4.12: Sea Barrier Concept Five Specifications

Barrier Characteristic Inner Barrier Outer Barrier Navigable Sections 1 1 Total NAV Length (mi) 0.20 0.50 Auxiliary Sections - 3 Total AUX Length (mi) - 1.50 Static Sections 2 4 Total Static Length (mi) 0.35 2.40 Barrier System Length (mi) 0.55 4.40

78 Chapter 5

Sea Barrier Cost Analysis

In order to establish a generalized construction cost for each of the proposed sea barrier designs, several flood barrier projects with similar concepts were analyzed. An overview of the project reports and design studies referenced is outlined below:

• Delta Works (Netherlands): Designed in response to the North Sea Flood of 1953, the Delta Works barriers were constructed from 1954-1997 as shown in Figure 5-1. As discussed in Chapter 4 with the OMOE reference projects, both static and dynamic features are incorporated in the Delta Works designs.

Figure 5-1: Delta Works Barrier Overview [Watersnood Museum, 2020]

79 • Hurricane and Storm Damage Risk Reduction System (New Orleans): Designed and constructed in response to Hurricane Katrina in 2005, the HSDRRS is comprised of a network of static and dynamic barriers as shown in Figure 5-2.

Figure 5-2: Hurricane and Storm Damage Risk Reduction System (HSDRRS) [USACE New Orleans District, 2018]

• Texas Gulf Coast Community Protection and Recovery District Study: In response to Hurricane Ike in 2008, the Storm Surge Suppression Study was launched to examine potential sea barrier designs for the upper Texas coast.

Figure 5-3: GCCPRD Storm Surge Suppression Study [GCCPRD, 2018]

80 • USACE Coastal Texas Feasibility Study: Incorporating the early work of the GCCPRD, as well as the Ike Dike proposals created at Texas A&M University, the USACE Coastal Texas Study is the federal version of the GCCPRD study with a larger scope. Even with the larger study area, there is still a substantial focus on the Galveston Bay and Houston Ship Channel sea barrier as shown in Figure 5-4. As with the previous projects mentioned above, the designs outlined in the USACE Coastal Texas Study include static and dynamic sea barriers.

Figure 5-4: USACE Coastal Texas Protection and Restoration Study [USACE Galveston District, 2018]

81 • USACE Norfolk Coastal Risk Management Feasibility Study: This study examines shoreline infrastructure projects aimed at protecting Norfolk from storm surge flooding. As shown in Figure 5-5, the study area is exclusive totheCity of Norfolk, and explores shoreline and shallow water barrier systems.

Figure 5-5: USACE Norfolk Coastal Risk Management Study [USACE Norfolk District, 2018]

82 • USACE New York-New Jersey Harbor and Tributaries Feasibility Study: This study is similar in scope and complexity to the USACE Texas Study with proposals for static and dynamic sea barriers spanning large waterways near New York City. As part of the design evaluations, the USACE developed a sea barrier cost model that will be outlined in the next section of this chapter.

Figure 5-6: USACE New York and New Jersey Harbor and Tributaries Study [USACE New York District, 2019]

83 Each of the projects and studies listed above provided a varying degree of ap- plicable data for establishing cost estimates of the Norfolk, Virginia sea barrier design concepts. For example, although the Delta Works were ideal OMOE reference projects due to their scale and pioneering status, the cost data was not directly comparable. In general, the cost data for the Delta Works was 20 to 40 years old and based on European construction metrics to include regulations, labor rates and ma- terial pricing. This cost data could have ultimately been converted to account for inflation and location variations with construction indices, however, the open source cost data lacked the details necessary to establish a satisfactory cost model. Sim- ilar issues regarding cost details arose with the HSDRRS projects in New Orleans and the USACE Coastal Texas Study. As with the Delta Works projects, the open source HSDRRS design reports focused on total construction costs versus component costs. Even with general project specifications, to include barrier dimensions and depth contours, the lack of itemized component level cost data prevented the project reports from being used as the singular source for creating a relevant cost model. Figure 5-7 shows the Seabrook Floodgate Complex and the West Closure Complex, both projects within the the HSDRRS. Both of these barrier systems utilize navigable sector gates, auxiliary flow sluice gates, and static seawalls which should make them prime cost comparison projects for the Norfolk sea barrier design concepts. But, with only bottom line cost data, and additional system features, such as the large West Closure Complex pumping station, factored into the total cost, the HSDRRS open source cost data was insufficient for a cost model. The USACE Coastal Texas Study also lacked detailed cost projections due to the early stage of the feasibility study. Figure 5-8 shows the preliminary broad stroke cost estimates for the Texas study. The highlighted section of the cost projections are associated with the Houston Ship Channel sea barrier which features a large navigable sector gate, auxiliary flow gates and static seawalls. However, only general estimates were provided as part of the preliminary USACE feasibility report. Overall, the data from these reports was use- ful in gaining a general understanding of cost ranges, but was insufficient, due to the bottom line or broad range cost data format, for establishing a cost model.

84 Figure 5-7: HSDRRS: Seabrook (Top) and West Closure (Bottom) [USACE New Orleans District, 2018]

Figure 5-8: USACE Coastal Texas Study Preliminary Cost Ranges [USACE Galveston District, 2018]

85 The USACE Norfolk Study and the GCCPRD Texas Study differed from the previously discussed reports in that the cost data provided was detailed and itemized to the component level with data for navigable sector gates, auxiliary flow gates and static structures. Figures 5-9 and 5-10 show sections of the cost analyses for both the USACE Norfolk and GCCPRD Texas studies respectively.

Figure 5-9: USACE Norfolk Coastal Risk Management Study Cost Data [USACE Norfolk District, 2018]

Figure 5-10: GCCPRD Storm Surge Suppression Study Cost Data [GCCPRD, 2018]

86 The USACE Norfolk Study and the GCCPRD Texas Study provided sufficient component level cost data to begin parametric analyses for flood barrier components. Utilizing this data, cost factors, in cost per linear foot, were established for shoreline seawalls, tidal floodwalls, sluice gates, miter gates and sectors gates. These costdata analyses can be found in Appendix C and will be discussed further in Chapter 7 as part of the shoreline infrastructure cost model. Although the cost data provided from these studies was an important step in establishing a cost model for this thesis, additional data points were desired to ensure the construction cost of the large scale sea barriers concepts proposed in Chapter 3 was accurately estimated. Additionally, a large portion of the data in these studies was tailored to shoreline infrastructure or shallow water dynamic barriers. For example, the proposed barrier across the mouth of the Lafayette River in the USACE Norfolk Study, has an average charted depth of approximately 4ft, with the deepest component being the 150ft sector gate spanning an 8.5ft deep channel [USACE Norfolk District, 2018]. For these reasons, additional cost data was necessary to ensure the scale of the sea barriers concepts proposed in this thesis was appropriately factored into the cost estimates. This additional cost data, tailored for large scale projects, would be provided in the USACE NY-NJ Study.

The NY-NJ Study compiled a comprehensive sea barrier data set, and established an associated cost model. A detailed discussion, and analysis, of this cost model can be found in the next section of this chapter, as well as in Appendix A. Figure 5-11 shows the sea barrier data set from the USACE NY-NJ Study.

Figure 5-11: Sea Barrier Reference Data for the USACE NY-NJ Study [USACE New York District, 2019]

87 5.1 Cost Model

The USACE NY-NJ Study examined 17 sea barrier projects with detailed design and cost data. Each of the barrier systems analyzed had a static and dynamic component, with the majority having navigable dynamic, auxiliary dynamic and static sections. Although additional sea barrier projects fall into this design category, those without available data across all reference categories, shown in Figure 5-11, were removed from the reference study. Additionally, projects that were similar in design but had additional features that skewed cost figures, such as the pumping station at the West Closure Complex in Figure 5-7, were also withheld from the reference database. With a consistent set of detailed barrier dimensions, to include lengths, heights and depths, component areas were calculated for the navigable, auxiliary and static sections of each sea barrier. Navigable and auxiliary dynamic areas included the associated support and stowage structures as shown in Figure 5-12. In this pro- file view of the Verrazano Narrows plan, the lengths and overall heights ofsection A, B and E are included in the auxiliary dynamic area calculation. In the same way, the entirety of sections C and D, to include the length and overall height of the artificial stowage islands, are included in the navigable dynamic area calculation [USACE New York District, 2019].

Figure 5-12: USACE NY-NJ Study Verrazano Narrows Sea Barrier Section Plan [USACE New York District, 2019]

A regression analysis was performed on the 18 variables in the reference database

88 shown in Figure 5-11. Those with high correlations, such as length and area of the same component type, were removed from further analysis. However, with low corre- lation between the static and dynamic barrier areas, the variables of highest interest to the USACE NY-NJ Study, additional analysis was conducted to determine the coefficients associated with each of the barrier types [USACE New York District, 2019]. The regression coefficients were applied to a cost formula as shown below:

Sea Barrier Cost = ($19,000 x NA) + ($14,000 x AA) + ($3,000 x DA)

NA is the Dynamic Navigable Area

AA is the Dynamic Auxiliary Area

DA is the Static Dam Area

A graphical analysis of the modeled cost versus actual cost of the sea barrier reference projects, as well as the estimated cost of each USACE NY-NJ Study design concept, based on the established cost model, are shown in Figure 5-13.

Figure 5-13: USACE NY-NJ Study Regression Formula and Data Plot [USACE New York District, 2019]

89 In order to better understand the sea barrier cost model, a regression analysis was preformed in Minitab. Figure 5-14 outlines the data used in the regression analysis. Utilizing the Minitab Fitted Regression Model and Line Plot modules, a regression summary and plot were generated as shown in Figures 5-15 and 5-16.

Figure 5-14: Reference Sea Barrier Data Table [USACE New York District, 2019]

Figure 5-15: Minitab Fitted Regression Model Summary

90 Figure 5-16: Minitab Fitted Regression Line Plot

As shown in Figures 5-13 and 5-15, there is some variation between the Minitab regression coefficients and those in NY-NJ Study. Most differences were attributed to rounding in order to create a clean cost formula. The variations are also relatively minor when considering the scale of the model, as well as the confidence and predic- tion intervals shown in Figure 5-16. Additional analysis, shown in Appendix A, was conducted to include testing the model on the USACE and GCCPRD TX Studies. Overall, the model provided reasonable results for baseline costs, but deviated from listed cost estimates after applying the recommended contingency rate. Furthermore, the cost model appeared to overestimate sector gate costs. This overestimation may be explained in Figure 5-13, where the New Bedford and Maeslant barriers, which both feature a sector gate as the central component, are well below the regression line. This likely indicates that the cost model is skewed toward barriers with more expensive navigable components such as the MOSE or Thames. Regardless, the cost model provides fairly accurate results, and will be utilized as published in the USACE NY-NJ Study, but with the emphasis that the final costs, adjusted for contingency, may be overstated for barriers with sector gates as the navigable component.

91 5.2 Cost Analysis

Cost estimates for the sea barrier concepts are shown in Tables 5.1-5.6 based on the NY-NJ Study cost model. A more detailed cost analysis can be found in Appendix B. Figures 5-17-5-22 illustrate the design concepts, where yellow lines are static DAM structures, blue lines are dynamic AUX sections, orange lines are dynamic NAV sector gates, and the brown lines are sector gate stowage areas. Design concepts are drawn to scale and may vary from the preliminary concepts shown in Chapter 3 as a result of additional design details being incorporated to include larger auxiliary flow sections. Figures 5-17-5-22 are considered the finalized sea barrier concept design drawings, and were referenced during the cost and performance analyses.

Table 5.1: Sea Barrier Design Concept One Cost Estimates

Barrier Type Number of Sections Length (mi) Cost (FY19) NAV 2 1.25 $ 7.69B AUX 8 7.30 $ 24.05B DAM 11 10.05 $ 5.32B

Total 21 18.60 $ 37.06B

Figure 5-17: Sea Barrier Design Concept One Diagram

92 Table 5.2: Sea Barrier Design Concept Two Cost Estimates

Barrier Type Number of Sections Length (mi) Cost (FY19) NAV 1 0.50 $ 3.26B AUX 4 1.50 $ 3.92B DAM 4 2.40 $ 1.10B

Total 9 4.40 $ 8.28B

Figure 5-18: Sea Barrier Design Concept Two Diagram

Table 5.3: Sea Barrier Design Concept Three Cost Estimates

Barrier Type Number of Sections Length (mi) Cost (FY19) NAV 1 0.50 $ 3.00B AUX 3 2.25 $ 5.45B DAM 5 2.80 $ 1.42B

Total 9 5.55 $ 9.87B

93 Figure 5-19: Sea Barrier Design Concept Three Diagram

Table 5.4: Sea Barrier Design Concept Four Cost Estimates

Barrier Type Number of Sections Length (mi) Cost (FY19) NAV 1 0.20 $ 1.25B AUX - - - DAM 2 0.35 $ 0.14B

Total 3 0.55 $ 1.39B

Figure 5-20: Sea Barrier Design Concept Four Diagram

94 Table 5.5: Sea Barrier Design Concept Five Cost Estimates

Barrier Type Number of Sections Length (mi) Cost (FY19) NAV 2 0.70 $ 4.51B AUX 3 1.50 $ 3.92B DAM 6 2.75 $ 1.24B

Total 11 4.95 $ 9.67B

Figure 5-21: Sea Barrier Design Concept Five Diagram

Table 5.6: Sea Barrier Design Concept Six Cost Estimates

Barrier Type Number of Sections Length (mi) Cost (FY19) NAV 2 0.70 $ 4.25B AUX 3 2.25 $ 5.45B DAM 7 3.15 $ 1.56B

Total 12 6.10 $ 11.26B

95 Figure 5-22: Sea Barrier Design Concept Six Diagram

The baseline construction costs shown in Tables 5.1-5.6 were derived from the USACE cost model, which estimates construction cost in FY2019 dollars. Table 5.7 shows the modeled cost of each design concept, and establishes a final cost based on inflation and contingency adjustments. An inflation rate was applied to shiftfrom FY19 to FY20, and a 40% contingency cost was added to account for the limited details inherent to a concept design as recommended in the USACE NY-NJ Study. An interesting result to note from Table 5.7 is the lower cost of SB2 compared to SB3, in spite of SB2 providing protection for a much larger area. Additionally, SB5 which combines the designs of SB2 and SB4 is less expensive than SB3. These cost trends will be examined along side the performance metrics derived in Chapter 4 in a cost versus performance analysis in Chapter 6.

Table 5.7: Sea Barrier Design Concept Cost Comparisons

SB 1 SB 2 SB 3 SB 4 SB 5 SB 6 FY19 Baseline ($B) 37.06 8.28 9.87 1.39 9.67 11.26 Inflation Adjustment ($B) 0.44 0.10 0.12 0.02 0.12 0.14 Contingency (40%) ($B) 15.00 3.35 3.99 0.56 3.91 4.56

Total FY20 Cost ($B) 52.50 11.73 13.98 1.97 13.70 15.96

96 Chapter 6

Sea Barrier Selection and Analysis

6.1 Cost vs Performance Analysis

The performance metrics established in Chapter 4 and the cost estimates derived in Chapter 5 were compared in a cost versus performance analysis. Figure 6-1 summa- rizes the cost and performance data from the previous chapters to include the figure of merit assigned to the design concepts for each performance category, the weighted sum of the figure of merits based on the factors outlined in Table 4.1, and thetotal fiscal year 2020 construction costs adjusted for inflation and contingency. Thetotal FY2020 estimated construction costs were analyzed in conjunction with the figure of merit weighted sums on a cost versus performance plot as shown in Figure 6-2.

Figure 6-1: Cost and Performance Data for the Sea Barrier Concepts

97 Figure 6-2: Cost vs Performance Analysis for the Sea Barrier Concepts

The blue oval drawn on Figure 6-2 indicates the area of focus for the optimal designs, with Sea Barrier Concept Five having the highest performance. Design Concept Five is the combination of Sea Barrier Design Two and Sea Barrier Design Four, the two other designs within the focus area highlighted on the graph. Sea Barrier Design Concept Five will be carried forward as the optimal design for the remainder of this report, however, it is important to note that a phased installation of Design Concepts Two and Four could also be implemented, based on budget availability, while still working within optimized design space. For example, even though Sea Barrier Four is insufficient to protect against the projected high water levels greater than1-YR storms in the year 2100, it would provide significant protection to the Southern and Eastern Branches of the Elizabeth River for present day storms, as well as projected tidal flooding. Table 6.1 and Figures 6-3-6-5 outline the design specifications of of Sea Barrier Design Concept Five with its outer and inner barriers. The outer barrier is located in the vicinity of the Hampton Roads Bridge-Tunnel, spanning from Willoughby Spit in Norfolk to Hampton. The inner barrier is situated near the Elizabeth River Tunnel, spanning from Norfolk to Pinner Point in Portsmouth.

98 Table 6.1: Sea Barrier Design Concept Five Overview

Gate Size (mi) Barrier Length (mi) Cost (FY20) Outer Barrier 0.24 4.40 $11.73B Inner Barrier 0.10 0.55 $1.97B Total Cost $13.70B

Figure 6-3: Optimal Design: Sea Barrier Concept Five

99 Figure 6-4: Sea Barrier Concept Five Design Specifications

Figure 6-5: Sea Barrier Concept Five Inner and Outer Barrier

100 Chapter 7

Shoreline Infrastructure Analysis

In place of a sea barrier system, comprehensive shoreline infrastructure, such as seawalls or levees, can protect estuary coastlines from flooding associated with a storm surge or sea level rise. These structures are typically less complex, and less expensive than a dynamic sea barrier when utilized to protect shorelines with limited development density, such as a seaside town with a seawall separating the buildings from the beach. However, along shorelines that are heavily developed with a mixture of residential, commercial, industrial and military properties, featuring piers, wharfs and promenades, a seawall cannot provide adequate protection without disrupting the functionality of these facilities. In this case, the piers, wharfs and promenades must be redesigned and incorporated into the overall shoreline barrier system. However, rebuilding and elevating these shoreline structures does not come without a substantial price increase to the overall shoreline barrier system. The cost factors associated with the varying shoreline barrier structures will be discussed in Section 7.1. Even if a shoreline barrier system can exclusively use more affordable structures such as a seawall or levee, the sheer expanse of these systems must also be taken into consideration. The tidal shoreline of the Chesapeake Bay and its tributaries is 11,684 miles, compared to only 7,863 miles of shoreline on the West Coast of the contiguous United States. Similarly, the combined Elizabeth River and Lafayette River tidal shoreline is 440 miles, spanning the cities of Norfolk, Portsmouth, Chesa- peake and Virginia Beach. This equates to a longer tidal shoreline for these two

101 rivers than the tidal shoreline of several states, such as Rhode Island or Delaware [NOAA, 2020b, Virginia Institute of Marine Science, 2020]. Figure 7-1 shows the extensive tidal shoreline within the otherwise landlocked City of Chesapeake, Virginia.

Figure 7-1: City of Chesapeake, Virginia Tidal Shoreline Overview [Virginia Institute of Marine Science, 2020]

102 The cost and complexity of establishing a shore barrier along a densely developed waterway, as well as the expanse of the system, will be explored through a series of cost and design analyses. The goal of this chapter will be to quantify the cost of a shore barrier system that safeguards the vulnerable shorelines within the notional protection zone of Sea Barrier Concept Five. Utilizing the analysis results, a cost comparison of the sea barrier concept to shoreline infrastructure alternative will be established. A second analysis will examine a hybrid shoreline barrier design, similar to the USACE Norfolk Study proposal that uses a combination of shoreline infrastructure and shallow water dynamic barrier systems. This design will serve as an optimized shoreline barrier system that limits the use of large scale, deep water dynamic barriers, while also decreasing the overall scope of the required shoreline infrastructure. A cost comparison of this optimized shoreline barrier and the associated sea barrier concept will also be conducted. In the end, the cost comparison results will assist in determining the optimal barrier system for the Norfolk, VA study area.

7.1 Shoreline Barrier System Cost Factors

The USACE New York-New Jersey Study established a set of cost factors for shoreline barrier systems to include seawalls, floodwalls, levees, flood gates, tide gates, elevated promenades and dunes as shown in Figure 7-2.

Figure 7-2: Shoreline Infrastructure Cost Factors (FY19 USD/LF) [USACE New York District, 2019]

103 This study referenced the NY-NJ Study cost factors associated with floodwalls, seawalls, elevated promenades and flood/tide gates. For this analysis, a floodwall was defined as a barrier structure installed in a known tidal zone such as ashallow waterway or marsh, with similarities to the combo walls listed in the USACE Norfolk Study cost data. A seawall, on the other hand, was designated as a barrier build on normally dry land, with comparisons to the T-Wall structures outlined in the Nor- folk study. A flood/tide gate was defined as a small scale dynamic barrier operating in shallow water or marsh areas. The flood gate cost factors were compared tothe miter and sluice gates listed in the Norfolk study. Finally, the elevated promenades were characterized as paved walkways or transitways running along a waterway, sup- ported by a fortified shoreline such as a bulkhead. The NY-NJ study cost factors, Norfolk study cost data and several other Norfolk area project reports were utilized to establish two sets of cost metrics for this study. First, cost factors were established to develop a notional cost of a shoreline infrastructure system spanning the entire protection area of Sea Barrier Concept Five to include Hampton Road, the James River, the Elizabeth River, and all associated tidal tributaries. In total, this accounted for approximately 2300 miles of tidal shoreline [Virginia Institute of Marine Science, 2020]. Conducting a detailed analysis for a shoreline barrier system of this magnitude was beyond the scope for this thesis. As a result, a cost estimation tool was established based on the cost factors discussed above, and the shoreline database of the Virginia Institute of Marine Science (VIMS). The VIMS database provides data for all tidal shorelines within Virginia. Referenc- ing the shoreline characteristics outlined in the VIMS database, four shoreline barrier types were established and assigned an associated cost factor as shown in Figure 7-3.

Figure 7-3: Shoreline Analysis One: Barrier Types and Cost Factors

104 Shoreline barrier type one was assigned the unlimited access seawall cost of $3,000 per linear foot from the NY-NJ Study due to the minimal development of these shoreline regions. The lack of existing shoreline structures provides for an easier construction process, as well as leeway in selecting the barrier location relative to the shoreline. Conversely, the limited access seawall cost factor of $4,500 per linear foot was established for shoreline type three to address the increased complexity and costs associated with constructing shoreline barriers on residential and commercial properties. In these cases, existing structures to include defended shorelines, small piers and wharfs, and miscellaneous outbuildings will increase the complexity of the construction operation, and increase associated costs to include compensation for property owners, construction mitigation, and post-construction restoration. Shoreline barrier type two and four were appointed the cost metrics for unlimited and limited access elevated promenades respectively. Type two shorelines, which include paved walkways and transitways, were considered to have relatively established construction practices. As a result, the baseline cost factor of $7,500 per linear foot was selected due to the routine nature of this type of work. Shoreline barrier type four, however, was associated with industrial and military properties. In this case, the limited access elevated promenade metric of $15,000 per linear foot was assigned to account for the increased complexity of construction on these densely developed shorelines, which include large scale wharfs and piers. Several industrial and military projects completed in the Norfolk area were analyzed to determine the costs associated with wharf and pier construction. For large scale military and industrial facilities, a cost factor range of $25,000 to $30,000 per linear foot was established. These cost factors are significantly higher than the $15,000 per linear foot selected to represent shoreline type four. This deviation is due to the fact that the military and industrial properties within the study area have a wide range of shoreline compositions ranging from wharfs and piers, to bulkheads and riprap. In order to prevent the overestimation of infrastructure costs associated with these properties, $15,000 per linear foot was selected as an average cost factor, representative of an entire facility. Additional analysis regarding the selection of cost factors can be referenced in Appendix C.

105 The second cost analysis was for a hybrid design which utilized a combination of shoreline infrastructure and shallow water dynamic barriers. Figure 7-4 outlines the shoreline barrier components, assigned cost factors and the associated references. Additional details regarding cost factor selections can be found in Appendix C.

Figure 7-4: Shoreline Analysis Two: Shoreline Barrier Cost Factors

7.2 Shoreline Infrastructure Cost Analysis

A shoreline infrastructure cost analysis was completed for the Sea Barrier Concept Five protection area using the cost factors outlined in Figure 7-3. Utilizing the VIMS Center for Coastal Research Management database, shoreline sections were catego- rized by type and susceptibility to flooding. The shoreline types are outlined below:

• Type 1: Agricultural, Bare, Forest, Grass and Shrub

• Type 2: Paved

• Type 3: Commercial and Residential

• Type 4: Industrial and Military

106 Shoreline sections were then analyzed based on elevation, with heights between zero to five feet above mean sea level classified as susceptible to flooding. Thechar- acterization of shoreline type and susceptibility to flooding assisted in determining if a barrier was needed, and if so, the associated cost of the barrier along a specific section of shoreline. This analysis process was conducted for all of the municipalities within the protection area of Sea Barrier Concept Five as shown in Figure 7-5.

Figure 7-5: VIMS Shoreline Data Sets (Denoted with Blue Stars) [Virginia Institute of Marine Science, 2020]

In the Cities of Norfolk, Portsmouth, Chesapeake, Virginia Beach and Hamp- ton, all shoreline types, classified as susceptible to flooding, were assigned aformof shoreline protection for this cost analysis. This was not the case, however, for the remaining counties where type one shorelines, which had limited to no development, were not assigned sea barrier protection. The decision to exclude shoreline barrier protection in these cases was based on development density, as well as the projected spread of flooding due to local topography as shown in Figure 7-6.

107 Figure 7-6: Shoreline Infrastructure Analysis Area [NOAA, 2020b]

The shoreline infrastructure analysis area, outlined in orange and based on the protection area of Sea Barrier Concept Five, shows widespread flooding in the areas immediately surrounding Norfolk during a 100 year storm event in the year 2100. However, the counties and cities situated to the northwest of Norfolk, along the James River, primarily witness flooding directly along the coast. For these reasons, only localized shoreline barrier systems protecting the developed shoreline regions were determined necessary outside of the five cities outlined above. In total, the exclusion of shoreline with elevations above six feet, as well as type one shoreline outside of the cities immediately surrounding Norfolk, decreased the shoreline requiring barrier protection from over 2000 miles to 795 miles [Virginia Institute of Marine Science, 2020]. Figure 7-7 outlines the results of the shoreline infrastructure cost analysis, with a total cost of $24.1B, excluding contingency adjustments. It is interesting to note that the Cities of Norfolk, Portsmouth, Chesapeake and Virginia Beach, that are situated

108 around the Elizabeth River, account for nearly 60 percent of the total shoreline barrier cost, while the much larger James River does not have as significant of an impact. This data point solidifies the importance of examining flood barrier options forthe Norfolk, VA study area.

Figure 7-7: Shoreline Infrastructure Cost Analysis Results

Adjusting for inflation and applying a 40 percent contingency rate, consistent with the sea barrier concept cost estimates, increases the shoreline infrastructure cost to $34.3B. In comparison, the cost of Sea Barrier Concept Five is $13.7B. In this case, implementing the sea barrier design could save upwards of $20B, with a benefit to cost ratio of 1.50. With this large variation in cost, it is unlikely thata regional planning organization would select a design consisting of exclusively shoreline infrastructure for this specific case. However, it would not be implausible for the uncoordinated, cumulative response of the 18 municipalities within this analysis area to end up with the majority of flood barrier infrastructure being shoreline based. In this case, the cost of a cumulative system could far exceed the cost of a single sea barrier project without the coordination of a regional planning entity. This trend may already be in progress with the ongoing USACE Norfolk Study limited in scope to municipal boundaries, excluding neighboring cities, Naval Station Norfolk and Norfolk International Terminal [USACE Norfolk District, 2018]. Nonetheless, at this early

109 planning stage, the Norfolk Study is still an important first step for addressing the flooding risk in the region. Additionally, the Norfolk Study proposes a hybrid barrier design, which utilizes a combination of shoreline and shallow water barriers, reducing the expanse of required shoreline infrastructure. The second barrier analysis in this chapter will focus on creating a hybrid design, and establishing a cost comparison between the hybrid shoreline barrier and sea barrier concept.

7.3 Hybrid Shoreline Barrier Cost Analysis

A hybrid shoreline barrier system was established as shown in Figure 7-8, with the red lines indicating shoreline barrier components within the inner sector gate of Sea Barrier Concept Five. The brown lines illustrate shoreline barrier locations outside of the inner gate, but still within the overall protection area of the sea barrier concept.

Figure 7-8: Hybrid Shoreline Barrier Design

110 A design and cost analysis was conducted for the hybrid shoreline barrier that falls within the protection zone of the inner sector gate. The barrier system consists of 38 miles of structure to include two sector gates, 34 miter gates and 22 sluice gates. Figure 7-9 shows three different views of the hybrid shoreline design with red lines indicating shoreline infrastructure and combo walls, orange lines representing sector gates, blue lines illustrating miter gates and yellow lines symbolizing sluice gates.

Figure 7-9: Hybrid Shoreline Barrier Section Overview

The two sector gates are situated at the boundary of the barrier system at the Albemarle-Chesapeake Canal and Dismal Swamp Canal, both part of the intracoastal waterway. The sector gates are 120ft and 150ft wide. The 34 miter gates are spread throughout the hybrid shoreline barrier system, with a median width of 70ft. The miter gates serve as auxiliary flow gates and provide access to residential portions

111 of the Elizabeth River for small pleasure crafts to transit. Sluice gates exclusively provide auxiliary flow to small inlets and marsh areas with gate widths ranging from 15ft to 30ft. Termination of the barrier structure on the southern and eastern branches of the Elizabeth River occurs at the transition point from primarily industrial to primarily residential shoreline. For the sections of the shoreline barrier design that overlapped with the proposals in the USACE Norfolk Study, an attempt was made to mirror the designs where practical. The major deviations with this design proposal include the termination of the eastern branch structure prior to Broad Creek, as well as the addition of shoreline infrastructure protecting shipyards and industrial areas to the south and east of downtown Norfolk. A comparison of the shoreline barrier designs is shown in Figure 7-10 with the Norfolk Study illustration on top.

Figure 7-10: Norfolk Shoreline Barrier Design Comparison [USACE Norfolk District, 2018]

112 Inclusion of the shipyards and industrial maritime facilities, situated along the Elizabeth River, within the bounds of the shoreline barrier increased the complexity of the design, but was determined to be essential in order to safeguard these important facilities. These private shipyards, although smaller in size compared to the public Norfolk Naval Shipyard, provide a vital maintenance capacity for USN ships, and play a significant role in the economy of Hampton Roads. As shown in Figure 7-11, the shorelines associated with these shipyards are a mixture of bulkheads, wharfs and piers that require a combination of mitigation efforts, ranging from seawall installation to the replacement of entire wharfs and piers, in order to sufficiently increase the elevation of these structures while also maintaining the intended functionality.

Figure 7-11: Waterfront Layout of the Elizabeth River Shipyards

The cost factors established for each of the shoreline barrier components, ranging from seawalls and miter gates, to wharf elevation and pier replacement, was discussed in Section 7.1 and outlined in Figure 7-4. Using these metrics, a cost analysis of the hybrid shoreline barrier was completed. An overview of the cost analysis results is shown in Figure 7-12, with the detailed cost analysis outlined in Appendix D.

113 Figure 7-12: Hybrid Shoreline Barrier Cost Analysis Overview

Figure 7-12 indicates that the total estimated construction cost of the hybrid shoreline barrier system is $2.54B prior to contingency and inflation adjustments. Adjusting to FY20 costs and applying the recommended 40 percent contingency rate, utilized as part of the sea barrier cost model, increases the shoreline barrier cost to $3.60B. In comparison, the cost of the inner barrier of Sea Barrier Concept Five is $1.97B. In this case, constructing the inner sea barrier would save approximately $1.6B in construction costs, with a benefit to cost ratio of 0.83. An interesting trend within the cost analysis results is the substantial portion, approximately 50 percent, of the overall construction cost associated with replacing low elevation piers, wharfs and quay walls at industrial, military and commercial facilities. Eliminating this cost by excluding industrial areas from the protection zone, with seawalls built inland of these facilities, would reduce the construction cost of the shoreline barrier to approximately the cost of the inner barrier of Sea Barrier Concept Five. However, this would require the private shipyards, and other industrial facilities stationed along the Elizabeth River, to shoulder the costs of redesigning and elevating shoreline facilities. Aside from the handful of petroleum storage facilities, the majority of these smaller scale industrial facilities would be unlikely to have sufficient capital to cover these flood mitigation costs without some form of government assistance. The private shipyards, for example, would presumably receive assistance from the federal government via the USN in order to preserve the vital maintenance capacity of these shipyards.

114 In most cases, the intended cost saving, associated with shifting seawalls inland of industrial facilities, would more than likely be eroded through subsequent assistance or mitigation programs, such as site clean-up for facilities closed and abandoned. In the end, excluding these facilities from the protection zone of the shoreline barrier system would be unlikely to produce cost savings significant enough to establish the shoreline barrier as the more cost effective option compared to the inner sea barrier.

The final aspect of this analysis would be to compare the cost of Design Concept Five to a hybrid shoreline system spanning the entire protection area. This would require a detailed analysis of the shoreline properties, and local topography, between Norfolk and Richmond. An analysis of this scale would require additional time beyond the limitations of this thesis, however, some general assessments can be conducted.

Implementing the hybrid shoreline barrier, compared to exclusively using shoreline infrastructure, for the protection area of the inner sea barrier, decreased the notional cost from $10.6B to $3.6B, an approximate reduction of two-thirds. Apply- ing the same reduction factor to the shoreline infrastructure cost of the entire sea barrier protection area, reduced the cost from $34.3B to $11.6B for a hybrid shoreline system. This would indicate that a hybrid shoreline barrier may be the more affordable option as compared to the $13.7B sea barrier, but there are several caveats to consider. First, the James River is navigable for merchant traffic from Hampton Roads to the Richmond Marine Terminal, one of the six Port of Virginia terminals [Virginia Port Authority, 2020]. Based on this fact, isolating portions of the river with smaller scale barriers, as was done with the Elizabeth River hybrid shoreline barrier concept, would not be practical. As a result, this leaves the majority of the James River, as well as several large tributaries such as the Appomattox and Chick- ahominy Rivers, in need of shoreline protection. Second, although sections of the James River are less susceptible to damaging tidal floods, due to increased shoreline elevations and decreased development densities, reports from Hurricane Isabel in 2003 reveal that this region is still at a significant risk. Portions of Richmond, and areas along the Appomattox River, experienced up to eight feet of storm surge during Hur- ricane Isabel, as far as 100 miles upriver from Hampton Roads [NOAA, 2004]. Based

115 on these two data points, and the fact that large portions of shoreline were already excluded during the infrastructure analysis due to reduced flooding susceptibility, a cost reduction of two-thirds is likely too extreme. Instead, a 50 percent reduction may be more realistic, which would only reduce the hybrid shoreline barrier cost to $17.2B as compared to the sea barrier cost of $13.7B. In order to gain an understanding of the scale of additional shoreline barrier costs in the Norfolk area, aside from those calculated for the inner barrier protection area, a generalized analysis of the port terminals and naval facilities was conducted. The same cost factors from the previous hybrid shoreline analysis were utilized to examine the cost of elevating piers, wharfs and quay walls at the facilities shown in Table 7.1. These cost estimates do not include seawalls or associated dynamic gates. Table 7.1: Barrier Cost Estimates for Shoreline Facilities

Maritime Facility Shoreline Barrier Cost Norfolk International Terminal (NIT) $595M Virginia International Gateway (VIG) $215M Portsmouth Marine Terminal (PMT) $230M Newport News Marine Terminal (NNMT) $400M Lambert Point Yard & MHI Shipyard $425M Naval Station Norfolk $700M Newport News Shipbuilding $625M Craney Island Fuel Depot $95M Total Cost with Contingency (FY20) $4.7B

This analysis reveals the magnitude of the costs associated with adapting these large shoreline facilities for sea level rise. Referencing these figures, and the hybrid shoreline barrier cost estimate of $3.6B for the inner protection area, an estimated $10B to $12B would be required to extend the hybrid shoreline barrier along all susceptible shorelines in the greater Norfolk, VA area, as depicted with the brown lines in Figure 7-8. Based on these estimates, it is unlikely that a hybrid shoreline barrier, designed for the entire sea barrier protection area, would be the more affordable flood barrier option. However, a comprehensive design and cost analysis would be required to confirm these generalized cost estimates.

116 Chapter 8

Conclusion

8.1 Project Accomplishments and Findings

A design, feasibility and cost analysis of sea barrier systems was conducted for the Norfolk, Virginia area, in an effort to provide an optimized solution for safeguarding the region from the projected impacts of sea level rise. Within the study area, Naval Station Norfolk (NSN) and Norfolk Naval Shipyard (NNSY) were selected as analysis locations. Referencing the 2017 NOAA intermediate scenario, the 2020 to 2100 shift in tidal datums for Naval Station Norfolk is shown in Table 8.1 [USACE, 2020]. Based on this data, a 1-YR storm surge in 2100 will be equivalent to a 100-YR storm in 2020, with water levels one foot higher than those recorded at the Sewells Point tide station during Hurricane Isabel in September of 2003 [NOAA, 2020c].

Table 8.1: Sea Level Rise Projections at Naval Station Norfolk

117 Figure 8-1: Hurricane Isabel Surge Levels (Norfolk, VA) [NOAA, 2020c, USN, 2003]

An analysis was then conducted using these sea level rise projections to determine if a sea barrier was feasible and warranted for the Norfolk, VA area. Portions of this analysis are shown in Figure 8-2 with LMSL and 1-YR Storm water levels depicted.

Figure 8-2: Flooding Analysis at NSN and NNSY in 2100 [NOAA, 2020b]

Based on the projected absence of LMSL flooding at NSN and NNSY in the year 2100, the implementation of a sea barrier system, to prevent coastal flooding at elevated water levels, was determined to be feasible. In contrast, if substantial

118 flooding was projected at LMSL, a dynamic sea barrier system designed with the purpose of mitigating coastal flooding, while also limiting disruptions to shoreline facilities and the requirement for the substantial elevation of infrastructure, would be obsolete from the offset due to near continuous gate closures. Following the feasibility determination, evidence supporting the justification of a sea barrier system was also required. This justification was provided with the 1-YR Storm projections, which indicated a potential for significant flooding on an annual basis, validating theneed for a robust protection system, such as a dynamic sea barrier. Following the feasibility analysis, an OMOE performance evaluation was completed in Chapter 4 and a cost analysis was conducted in Chapter 5. A cost versus performance analysis established Sea Barrier Concept Five as the optimal design. An overview of Sea Barrier Concept Five is provided in Figures 8-3 and 8-4.

Figure 8-3: Recommended Sea Barrier Concept

119 Figure 8-4: Sea Barrier Concept Overview

The final aspect of this thesis was the cost comparison of the selected seabarrier design to a series of shoreline barrier alternatives, to determine the most cost effective approach for coastal flooding protection. A cost comparison of shore based infrastructure, estimated at $34.3B, to the sea barrier cost of $13.7B, provided a benefit to cost ratio of 1.50. A second cost analysis of a hybrid shoreline barrier system, estimated at $3.60B, to the inner sea barrier cost of $1.97B, produced a benefit to cost ratio of 0.83. In both cases, the sea barrier concept was the most cost effective solution for flood protection. Lastly, a generalized cost assessment of a hybrid shore barrier system, spanning the entirety of the sea barrier protection area, was compared to the cost of the sea barrier system. In this case, it was estimated that the sea barrier concept would still be the more affordable option, but with a significantly lower benefit to cost ratio of approximately 0.10 to 0.20. In all three cases, thecost comparisons were based on broad scale models or parametric examinations. As such, detailed design studies would be required to confirm the cost estimates of both the sea barrier system, and shoreline infrastructure. However, even with the potential for cost model inaccuracies, there is clear evidence that a sea barrier system, designed to protect the greater Norfolk, VA area from the impacts of coastal flooding associated with sea level rise, is well worth further consideration and analysis.

120 As a final summary, a list of key findings and recommendations is listed below:

First, the Norfolk, VA sea level rise projections, and ongoing coastal flooding trends in the Chesapeake Bay region, cannot afford to be overlooked or under- stated. The concentration of military, shipyard, and port facilities in this region is second to none, and requires extensive regional planning to mitigate the potential for catastrophic flooding at these facilities. Ongoing efforts to address therisk of coastal flooding, such as the Norfolk Coastal Storm Risk Management Feasibility Study [USACE Norfolk District, 2018], are essential first steps, but the scope is far too narrow. A regional plan that works to establish comprehensive flood protection infrastructure for the entire Hampton Roads area will likely represent the most cost effective approach, and provide the best chance of mitigating the flooding riskforthe largest number of shoreline facilities.

Second, considering a sea barrier system, to protect the region from the risk of coastal flooding, is a bold and expensive initiative. However, as illustrated throughout this thesis, a sea barrier may very well be the optimal, and most practical option. The cost of Sea Barrier Concept Five is substantial, but the cost of constructing shoreline or near shore defenses that protect an equivalent area is likely more expensive. Providing shoreline protection for residential areas, or an area of limited development density, can be relatively straightforward and affordable. However, elevating and adapting a shoreline facility such as a shipyard, to prevent flooding while also maintaining the required functionality, is a monumental challenge. The shoreline infrastructure cost estimates in this thesis account for elevating piers and wharfs, increasing the height of dry dock caissons, and installing seawalls. However, facility adaptation costs at large shipyards such as Norfolk Naval or Newport News would likely extend well inland of the shoreline in order to preserve the functionality of the yard. These additional changes would likely include elevating storage facilities and work shops to be on the same level as the piers and wharfs, in order to maintain work and process flows within the yard. In summary, adapting some shoreline facilities may end up being closer to a complete rebuild, than simply building a seawall. How- ever, the difficulty of adapting shoreline facilities, and designing a diverse networkof

121 shoreline barriers, can be avoided with the construction of a sea barrier system.

Third, sea barrier systems have conventionally been built to protect against storm surges. However, in this case, the inner sea barrier of Design Concept Five will also be utilized to prevent flooding at MHHW, and the outer sea barrier may alsobe required to close at the highest of annual tides. This concept of operation will require coordination and consistent monitoring to determine when the sector gates need to be closed, and adjust port operations accordingly. If sea levels continue to rise above the year 2100 projections, and the closure of the main sector gate becomes more frequent, a lock system can be added to the design to allow for continued traffic flow during closures. If seas continue to rise to levels where the sector gate is always closed, a permanent shift to a lock and dam system may be required. Conversely, the rebuilding of all shoreline facilities to a new benchmark level, or relocation of facilities could occur. In this case, the shore barrier system would have provided valuable time to properly plan for these monumental changes to shoreline facilities. These scenarios represent the long term extremes associated with sea level rise projections, but warrant a quick discussion to ensure a theoretical mitigation plan is available.

Fourth, although the year 2100 represents an extended timetable, the effects of sea level rise in the Norfolk, VA will become more readily apparent with each passing decade. Implementing a sea barrier system sooner than later, can safeguard this region from the debilitating coastal flooding associated with sea level rise, but also from the present day risk of hurricanes and extratropical cyclones. Figure 8-5 shows the present day storm surge risk at NNSY from a category four hurricane. Fortunately, the Chesapeake Bay has had a limited number of direct interactions with hurricanes, with the Hurricane of 1933 and Hurricane Isabel in 2003 being the most consequential storms with a category two status [NWS, 2020]. However, a higher category storm could severely damage critical shoreline facilities causing lasting impacts, such as with Hurricane Michael in 2018 that damaged Eastern Shipbuilding Company in Florida. The shipyard damage caused construction delays of up to a year with the USCG Offshore Patrol Cutter program [Werner, 2019]. The implementation of a sea barrier in the Norfolk, VA area could mitigate storm surge damage to similar critical facilities.

122 Figure 8-5: Category Four Hurricane Surge Projections [Kusnetz, 2018]

Lastly, the concepts developed in this thesis can be applied to other study locations with similar topography. One of these concepts is that a shore barrier design, despite its perceived higher construction cost, may represent the more affordable option compared to shoreline barriers for estuaries of medium to large size. One of these comparable locations is the San Francisco Bay which has near ideal topography

123 with limited flooding along the mountainous Pacific coastline and a narrow harbor entrance, but susceptible shoreline to coastal flooding within the bay as shown in Figure 8-6. As with Norfolk, VA, a sea barrier concept may be a suitable option for this location.

Figure 8-6: Comparable Study Location: San Francisco Bay [NOAA, 2020b]

8.2 Areas for Further Work

There are two areas recommended for further work. First, an in-depth design and cost analysis of a hybrid shoreline barrier for the James River region should be completed. A generalized analysis was conducted for this thesis, but a comprehensive cost comparison is required to confirm the most cost effective barrier design for the Norfolk, VA area. Second, an in-depth environmental analysis should be conducted to better determine the trade-offs associated with the recommended sea barrier locations and concepts of operation. Additionally, as dynamic barrier systems, both near shore or deep water, increase in number as a result of sea level rise, extensive environmental mitigation will also be required. Examining the potential for pumping systems to circulate flow, or transit paths for sea life migrations, are two of the many topicsthat should be explored in conjunction with the implementation of sea barrier systems.

124 Appendix A

Sea Barrier Cost Model

A sea barrier cost model was established by the United States Army Corps of Engi- neers New York District as part of the New York-New Jersey Harbor and Tributaries Coastal Storm Risk Management Feasibility Study. A February 2019 interim report for the NY-NJ Feasibility Study outlines a cost formula for sea barriers based the static and dynamic square footage of a given design. Static sections of the seawall are designated as DAM Areas (DA) and dynamic sections of the seawall are designated as either AUX Areas (AA) for auxiliary flow gates or NAV Areas (NA) for navigational gates. It is important to note that the NAV and AUX areas account for the support and stowage structures of the navigation and auxiliary gates in addition to the dynamic gates. These support structures can range from sluice gate guide pillars to the large artificial islands associated with the stowage of sector gates. The generalized area for the cost model is calculated by using the length and total height, measured from the seafloor to the top of each structure, for DAM, AUX and NAV sections of the barrier. The cost model formula is shown below:

Sea Barrier Cost = ($19,000 x NA) + ($14,000 x AA) + ($3,000 x DA)

This appendix outlines the USACE sea barrier database, regression results and finalized cost model. Additionally, a photo catalog of the reference sea barriers,a regression analysis conducted in Minitab and a comparative analysis of cost model results to published cost estimates is provided in this appendix.

125 USACE NY-NJ Feasibility Study Sea Barrier Cost Model Overview

[USACE New York District, 2019] Reference Sea Barrier Photo Catalog

1. Hollandsche Ijssel (Netherlands [Delta Works Program])

Source: [Watersnood Museum, 2020]

2. New Bedford (USA-MA)

Source: Marinas

3. Stamford (USA-CT)

Source: New England Boating

4. Eider (Germany)

Source: STAM

5. Hull (England)

Source: BBC

6. Thames (England)

Source: UK Department of Environment

7. Eastern Schedlt (Netherlands [Delta Works Program]) [OMOE Scale Reference Project]

Source: [Watersnood Museum, 2020]

8. Maeslant (Netherlands [Delta Works Program]) [OMOE Scale Reference Project]

Source: [Watersnood Museum, 2020]

9. Hartel (Netherlands [Delta Works Program])

Source: [Watersnood Museum, 2020]

10. Ramspol (Netherlands)

Source: Delta Marine Consultants

11. Ems (Germany)

Source: Structurae

12. St. Petersburg (Russia)

Source: TRANSMOST

13. IHNC (USA-LA [HSDRRS])

Source: [USACE New Orleans District, 2018]

14. Seabrook (USA-LA [HSDRRS])

Source: [USACE New Orleans District, 2018]

15. Harvey Canal (USA-LA [HSDRRS])

Source: [USACE New Orleans District, 2018]

16. GIWW (USA-LA [HSDRRS])

Source: [USACE New Orleans District, 2018]

17. MOSE (Italy)

Source: PBS

Barrier Structure Type Overview

Barrier Barrier Barrier NAV AUX DAM Number Name Location Structure Type Structure Structure Type Type 1 Hollandsche Ijssel Netherlands Sluice and Miter - Seawall 2 New Bedford USA-MA Sector Gate - Seawall/Levee 3 Samford USA-CT Flap Gate - Seawall/Levee 4 Eider Germany Miter Gate Sluice Gate Seawall 5 Hull England Sluice Gate - Seawall 6 Thames England Rotating Gate Rotating Gate Seawall 7 Eastern Schedlt Netherlands Miter Gate Sluice Gate Seawall/Levee 8 Maeslant Netherlands Sector Gate - Seawall 9 Hartel Netherlands Sluice Gate - Seawall 10 Ramspol Netherlands Inflatable - Seawall 11 Ems Germany Rotating Gate Sluice Gate Seawall 12 St. Petersburg Russia Sector Gate Sluice Gate Seawall/Levee 13 IHNC USA-LA Sector and Sluice Barge Gate Seawall 14 Seabrook USA-LA Sector Gate Sluice Gate Seawall 15 Harvey Canal USA-LA Sector and Miter - Seawall 16 GIWW USA-LA Sector Gate Barge Gate Seawall 17 MOSE Italy Flap, Sector, Sliding Flap Gate Seawall/Levee MINITAB Regression Analysis

USACE NY-NJ Study Sea Barrier Cost Model Comparison Analysis

Cost Estimate Comparison: Sea Barrier Cost Model Output for the USACE Texas Gulf Coast Study Barrier Type Length (ft) Depth (Below MSL, ft) Total Height (Depth+18, ft) Area (ft2) Cost Factor Construction Cost Contingency Cost Total Cost DAM 320 0 18 5760 $ 3,000.00 $ 17,280,000.00 $ 6,912,000.00 $ 24,192,000.00 DAM 700 40 58 40600 $ 3,000.00 $ 121,800,000.00 $ 48,720,000.00 $ 170,520,000.00 NAV (Island) 950 45 63 59850 $ 19,000.00 $ 1,137,150,000.00 $ 454,860,000.00 $ 1,592,010,000.00 NAV (Gate) 1200 60 78 93600 $ 19,000.00 $ 1,778,400,000.00 $ 711,360,000.00 $ 2,489,760,000.00 NAV (Island) 950 30 48 45600 $ 19,000.00 $ 866,400,000.00 $ 346,560,000.00 $ 1,212,960,000.00 AUX 2706 30 48 129888 $ 14,000.00 $ 1,818,432,000.00 $ 727,372,800.00 $ 2,545,804,800.00 AUX 1952 15 33 64416 $ 14,000.00 $ 901,824,000.00 $ 360,729,600.00 $ 1,262,553,600.00 DAM 633 8 26 16458 $ 3,000.00 $ 49,374,000.00 $ 19,749,600.00 $ 69,123,600.00 AUX 144 8 26 3744 $ 14,000.00 $ 52,416,000.00 $ 20,966,400.00 $ 73,382,400.00 DAM 1000 6 24 24000 $ 3,000.00 $ 72,000,000.00 $ 28,800,000.00 $ 100,800,000.00 DAM 1032 2 20 20640 $ 3,000.00 $ 61,920,000.00 $ 24,768,000.00 $ 86,688,000.00 Total 11587 $ 6,876,996,000.00 $ 9,627,794,400.00

Analysis: The sea barrier cost model provided a reasonable estimate ($6.88B), compared to the cost range ($5.10B-$6.30B) listed in the USACE Texas report, when the recommended 40 percent contingency rate was not applied. The TX Study cost projection shown above had already been adjusted for contingency. Although this type of comparison may have some inaccuracy based on the granularity of the area inputs, the magnitude of the cost estimate deviation, following the contingency adjustment, is significant enough to provide a sound conclusion. In this case, the TX Study cost estimate, adjusted for contingency, is within a reasonable range of the non-adjusted sea barrier cost model projection. A second analysis, shown below, compares the only sector gate costs from the sea barrier model and the GCCPRD TX Gulf Coast report. The previous conclusion that the model is more accurate when the contingency adjustment is not applied holds true, however, the cost deviation is more substantial when only analyzing the sector gates. This finding makes sense when examining the Minitab analysis, as well as the NY-NJ Study cost model graph at the beginning of this appendix. First, the AUX data had the highest contribution to the regression at 49 percent, compared to the NAV data at 25 percent. Second, two of the most comparable sector gate designs within the regression database are Maeslantkering and New Bedford, both of which are well below the regression line. Overall, the findings indicate that the model is not ideally suited for sector gates, but performs reasonably when analyzing the entire sea barrier

Cost Estimate Comparison: Sea Barrier Cost Model Output for the GCCPRD Texas Gulf Coast Study Projected Cost Cost/Linear Foot Cost/Square Foot Cost/Square Foot Modeled Cost Cost Category (TX GCCPRD Report) (TX GCCPRD Report) (TX GCCPRD Report) (NY-NJ Study Cost Model) (NY-NJ Study Cost Model) [Adjusted from FY15 to FY19] TX Cost Total (Sector Gate, w/o Cont) $ 786,505,366.80 $ 655,421.14 $ 8,402.84 $ 19,000.00 $ 1,778,400,000.00 TX Cost Total (Sector Gate, w/ Cont) $ 1,101,107,513.52 $ 917,589.59 $ 11,763.97 $ 26,600.00 $ 2,489,760,000.00

TX Cost Total (Stowage Island, w/o Cont) $ 835,798,018.32 $ 439,893.69 $ 11,730.50 $ 19,000.00 $ 1,353,750,000.00 TX Cost Total (Stowage Island, w/ Cont) $ 1,170,117,226.08 $ 975,097.69 $ 16,422.70 $ 26,600.00 $ 1,895,250,000.00 Itemized Cost Summary - HOUSTON SHIP CHANNEL BARRIER Item Description Quantity Unit Unit Cost Total 40% Total with Subtotals Contingency Contingency Total Barrier Length 9,850 LF Floating Sector Gate (2 leafs) Steel Fabrication 75,744 TON $8,000 $605,952,000 $242,380,800 $848,332,800 Mechanical LS 5.0% $30,297,600 $12,119,040 $42,416,640 Electrical LS 5.0% $30,297,600 $12,119,040 $42,416,640 Gate Transport LS 0.5% $3,029,760.00 $1,211,904 $4,241,664 Gate Installation LS 0.5% $3,029,760.00 $1,211,904 $4,241,664 $941,649,408 Support Structure on Ground (Island) Mobilization & Demobilization Use 3.5 % of construction cost based on CPRA$1,600,986 diversion estimating $640,394 $2,241,381 Pile Foundation 36" Pipe Piles 20,057 LF $225 $4,512,780 $1,805,112 $6,317,892 Foundation Concrete (Dry Dock) 31,518 CY $985 $31,045,663 $7,761,416 $38,807,079 Structural Concrete (Ball Joint) 10,184 CY $1,000 $10,184,020 $2,546,005 $12,730,025 $60,096,377 Sill Improvement Mobilization & Demobilization Use 3.5 % of construction cost based on CPRA$479,551 diversion estimating $191,821 $671,372 Filter Bed 116,219 CY $14 $1,627,070 $406,767 $2,033,837 Concrete Sill Blocks 13,416 CY $900 $12,074,400 $3,018,600 $15,093,000 $17,798,209 $1,019,543,994 Artificial Island (2) Coffer Cells Steel Sheet Pile Type PZ 27 2,341,398 SF $75 $175,604,819 $70,241,928 $245,846,747 Dredging of Cells (10 ft) 148,315 CY $6 $815,730 $326,292 $1,142,022 Sand Fill 1,229,247 CY $25 $30,731,164 $12,292,466 $43,023,630 $290,012,399 Cofferdam Bottom Excavation 346,659 CY $17 $5,893,207 $2,357,283 $8,250,490 Jet Grouting at Sill 1,979,895 CY $200 $395,979,076 $158,391,630 $554,370,706 Sand Fill 2,773,274 CY $25 $69,331,850 $27,732,740 $97,064,590 Riprap 802,439 TON $90 $72,219,467 $28,887,787 $101,107,253 Approach Guide Walls 1 LS $8,000,000 $8,000,000 $3,200,000 $11,200,000 $771,993,039 Surface Treatment Riprap (Class 250 lb). 54,404 TON $90 $4,896,342 $1,958,537 $6,854,879 Grass/Seeding 15 AC $4,500 $67,680 $27,072 $94,752 Misc. Roadway 2,501 LF $275 $687,720 $275,088 $962,808 Boat Dock, Barge, Mooring Dolphins 1 EA $2,840,000 $2,840,000 $1,136,000 $3,976,000 Vehicle Access Bridge from Dock 1 EA $6,820,000 $6,820,000 $2,728,000 $9,548,000 $21,436,439 $1,083,441,876 Appendix B

Sea Barrier Cost Analysis

This appendix outlines the sea barrier concept cost analysis process. A design synopsis is shown, detailing the components and characteristics associated with each of the sea barrier concepts, followed by a detailed overview of the cost analysis using the cost factors discussed in Appendix A. Sea barrier designs were separated into subsections in order to establish accurate average water depths. For example, although there are only 11 DAM sections for Design Concept One, the static sections were separated into 22 subsections to better match depth contours. Figure B-1 shows the outline of Design Concept One depicted as a black line, with a red box around the largest of several significant depth contour changes along the proposed sea barrier.

Figure B-1: Chesapeake Bay Chart

139 Design Concept One NAV Gates 2 NAV Gate Lengths (mi) 0.24 / 0.35 Avg MLLW Depth (ft) 52.50 Total NAV Length (mi) 1.25 Total NAV Cost (FY19) $ 7,689,528,000.00

AUX Sections 8 Avg MLLW Depth (ft) 27.25 Total AUX Length (mi) 7.30 Total AUX Cost (FY19) $ 24,053,568,000.00

DAM Sections 11 Avg MLLW Depth (ft) 16.59 Total DAM Length (mi) 10.05 Total DAM Cost (FY19) $ 5,319,072,000.00

Total Structure Length (mi) 18.60 Total Structure Cost (FY19) $ 37,062,168,000.00

Total Structure Cost (FY20) $ 37,506,914,016.00

Total Structure Cost $ 52,509,679,622.40 (FY20 with 40% Contingency)

Design Concept Two NAV Gates 1 NAV Gate Lengths (mi) 0.24 Avg MLLW Depth (ft) 50.00 Total NAV Length (mi) 0.50 Total NAV Cost (FY19) $ 3,260,400,000.00

AUX Sections 3 Avg MLLW Depth (ft) 26.75 Total AUX Length (mi) 1.50 Total AUX Cost (FY19) $ 3,917,760,000.00

DAM Sections 4 Avg MLLW Depth (ft) 14.40 Total DAM Length (mi) 2.40 Total DAM Cost (FY19) $ 1,098,028,800.00

Total Structure Length 4.40 Total Structure Cost (FY19) $ 8,276,188,800.00

Total Structure Cost (FY20) $ 8,375,503,065.60

Total Structure Cost $ 11,725,704,291.84 (FY20 with 40% Contingency)

Design Concept Three NAV Gates 1 NAV Gate Lengths (mi) 0.24 Avg MLLW Depth (ft) 50.00 Total NAV Length (mi) 0.50 Total NAV Cost (FY19) $ 2,999,568,000.00

AUX Sections 3 Avg MLLW Depth (ft) 20.00 Total AUX Length (mi) 2.25 Total AUX Cost (FY19) $ 5,451,600,000.00

DAM Sections 5 Avg MLLW Depth (ft) 15.00 Total DAM Length (mi) 2.80 Total DAM Cost (FY19) $ 1,417,680,000.00

Total Structure Length 5.55 Total Structure Cost (FY19) $ 9,868,848,000.00

Total Structure Cost (FY20) $ 9,987,274,176.00

Total Structure Cost $ 13,982,183,846.40 (FY20 with 40% Contingency) Design Concept Four NAV Gates 1 NAV Gate Lengths (mi) 0.10 Avg MLLW Depth (ft) 50.00 Total NAV Length (mi) 0.20 Total NAV Cost (FY19) $ 1,254,000,000.00

AUX Sections - Avg MLLW Depth (ft) - Total AUX Length (mi) - Total AUX Cost (FY19) -

DAM Sections 2 Avg MLLW Depth (ft) 10.00 Total DAM Length (mi) 0.35 Total DAM Cost (FY19) $ 138,600,000.00

Total Structure Length 0.55 Total Structure Cost (FY19) $ 1,392,600,000.00

Total Structure Cost (FY20) $ 1,409,311,200.00

Total Structure Cost $ 1,973,035,680.00 (FY20 with 40% Contingency)

Design Concept Five (Concepts Two & Four) NAV Gates 2 NAV Gate Lengths (mi) 0.24 / 0.10 Avg MLLW Depth (ft) 50.00 Total NAV Length (mi) 0.70 Total NAV Cost (FY19) $ 4,514,400,000.00

AUX Sections 3 Avg MLLW Depth (ft) 26.75 Total AUX Length (mi) 1.50 Total AUX Cost (FY19) $ 3,917,760,000.00

DAM Sections 6 Avg MLLW Depth (ft) 13.14 Total DAM Length (mi) 2.75 Total DAM Cost (FY19) $ 1,236,628,800.00

Total Structure Length 4.95 Total Structure Cost (FY19) $ 9,668,788,800.00

Total Structure Cost (FY20) $ 9,784,814,265.60

Total Structure Cost $ 13,698,739,971.84 (FY20 with 40% Contingency)

Design Concept Six (Concepts Three & Four) NAV Gates 2 NAV Gate Lengths (mi) 0.24 / 0.10 Avg MLLW Depth (ft) 50.00 Total NAV Length (mi) 0.70 Total NAV Cost (FY19) $ 4,253,568,000.00

AUX Sections 3 Avg MLLW Depth (ft) 20 Total AUX Length (mi) 2.25 Total AUX Cost (FY19) $ 5,451,600,000.00

DAM Sections 7 Avg MLLW Depth (ft) 13.75 Total DAM Length (mi) 3.15 Total DAM Cost (FY19) $ 1,556,280,000.00

Total Structure Length 6.10 Total Structure Cost (FY19) $ 11,261,448,000.00

Total Structure Cost (FY20) $ 11,396,585,376.00

Total Structure Cost $ 15,955,219,526.40 (FY20 with 40% Contingency) Design Concept 1 (Chesapeake Bay Bridge Tunnel Sea Barrier) Sea Barrier Section Sea Barrier Sea Barrier Section Length Section Length Height above Avg Depth below Total Height Total Area Cost Fator Cost Category Section Start (mi) Section End (mi) (mi) (ft) MLLW (ft) MLLW (ft) (ft) (ft2) (FY19 USD) (FY19 USD) Static 0.00 0.95 0.95 5016 15 0 15 75240 $3,000 $ 225,720,000.00 Static 0.95 1.00 0.05 264 15 1 16 4224 $3,000 $ 12,672,000.00 AUX 1.00 1.30 0.30 1584 15 3 18 28512 $14,000 $ 399,168,000.00 Static 1.30 1.35 0.05 264 15 1 16 4224 $3,000 $ 12,672,000.00 Static 1.35 1.75 0.40 2112 15 1 16 33792 $3,000 $ 101,376,000.00 Static 1.75 3.10 1.35 7128 15 0 15 106920 $3,000 $ 320,760,000.00 Static 3.10 3.25 0.15 792 15 9 24 19008 $3,000 $ 57,024,000.00 AUX 3.25 4.25 1.00 5280 15 41 56 295680 $14,000 $ 4,139,520,000.00 Static 4.25 5.05 0.80 4224 15 35 50 211200 $3,000 $ 633,600,000.00 Static 5.05 5.50 0.45 2376 15 9 24 57024 $3,000 $ 171,072,000.00 AUX 5.50 6.50 1.00 5280 15 7 22 116160 $14,000 $ 1,626,240,000.00 Static 6.50 7.00 0.50 2640 15 17 32 84480 $3,000 $ 253,440,000.00 AUX 7.00 8.00 1.00 5280 15 41 56 295680 $14,000 $ 4,139,520,000.00 Static 8.00 8.75 0.75 3960 15 19 34 134640 $3,000 $ 403,920,000.00 Static 8.75 8.98 0.23 1214.4 15 21 36 43718.4 $3,000 $ 131,155,200.00 NAV (Stowage) 8.98 9.11 0.13 686.4 15 51 66 45302.4 $19,000 $ 860,745,600.00 NAV (Gate) 9.11 9.35 0.24 1267.2 15 55 70 88704 $19,000 $ 1,685,376,000.00 NAV (Stowage) 9.35 9.48 0.13 686.4 15 49 64 43929.6 $19,000 $ 834,662,400.00 Static 9.48 9.57 0.09 475.2 15 19 34 16156.8 $3,000 $ 48,470,400.00 Static 9.57 10.00 0.43 2270.4 15 17 32 72652.8 $3,000 $ 217,958,400.00 Static 10.00 11.00 1.00 5280 15 43 58 306240 $3,000 $ 918,720,000.00 AUX 11.00 12.00 1.00 5280 15 31 46 242880 $14,000 $ 3,400,320,000.00 Static 12.00 12.50 0.50 2640 15 25 40 105600 $3,000 $ 316,800,000.00 AUX 12.50 13.50 1.00 5280 15 43 58 306240 $14,000 $ 4,287,360,000.00 Static 13.50 14.00 0.50 2640 15 45 60 158400 $3,000 $ 475,200,000.00 Static 14.00 14.12 0.12 633.6 15 19 34 21542.4 $3,000 $ 64,627,200.00 NAV (Stowage) 14.12 14.32 0.20 1056 15 37 52 54912 $19,000 $ 1,043,328,000.00 NAV (Gate) 14.32 14.67 0.35 1848 15 50 65 120120 $19,000 $ 2,282,280,000.00 NAV (Stowage) 14.67 14.87 0.20 1056 15 34 49 51744 $19,000 $ 983,136,000.00 Static 14.87 15.00 0.13 686.4 15 19 34 23337.6 $3,000 $ 70,012,800.00 Static 15.00 15.50 0.50 2640 15 33 48 126720 $3,000 $ 380,160,000.00 AUX 15.50 16.50 1.00 5280 15 23 38 200640 $14,000 $ 2,808,960,000.00 Static 16.50 17.00 0.50 2640 15 25 40 105600 $3,000 $ 316,800,000.00 AUX 17.00 18.00 1.00 5280 15 29 44 232320 $14,000 $ 3,252,480,000.00 Static 18.00 18.40 0.40 2112 15 7 22 46464 $3,000 $ 139,392,000.00 Static 18.40 18.60 0.20 1056 15 0 15 15840 $3,000 $ 47,520,000.00 Total Length 18.60 98208 Total Cost (FY19) $ 37,062,168,000.00 Total Cost (FY20) $ 37,506,914,016.00 Total Cost $ 52,509,679,622.40 (FY20 with Contingency)

Design Concept 2 (Hampton Roads Bridge Tunnel Sea Barrier) Sea Barrier Section Sea Barrier Sea Barrier Section Length Section Length Height above Avg Depth below Total Height Total Area Cost Fator Cost Category Section Start (mi) Section End (mi) (mi) (ft) MLLW (ft) MLLW (ft) (ft) (ft2) (FY19 USD) (FY19 USD) Static 0.00 0.50 0.50 2640.0 15 5 20 52800.0 $3,000 $ 158,400,000.00 AUX 0.50 1.00 0.50 2640.0 15 5 20 52800.0 $14,000 $ 739,200,000.00 Static 1.00 1.36 0.36 1900.8 15 7 22 41817.6 $3,000 $ 125,452,800.00 AUX 1.36 1.56 0.20 1056.0 15 40 55 58080.0 $14,000 $ 813,120,000.00 NAV (Stowage) 1.56 1.69 0.13 686.4 15 50 65 44616.0 $19,000 $ 847,704,000.00 NAV (Gate) 1.69 1.93 0.24 1267.2 15 50 65 82368.0 $19,000 $ 1,564,992,000.00 NAV (Stowage) 1.93 2.06 0.13 686.4 15 50 65 44616.0 $19,000 $ 847,704,000.00 AUX 2.06 2.36 0.30 1584.0 15 55 70 110880.0 $14,000 $ 1,552,320,000.00 Static 2.36 2.80 0.44 2323.2 15 45 60 139392.0 $3,000 $ 418,176,000.00 Static 2.80 3.40 0.60 3168.0 15 10 25 79200.0 $3,000 $ 237,600,000.00 AUX 3.40 3.90 0.50 2640.0 15 7 22 58080.0 $14,000 $ 813,120,000.00 Static 3.90 4.40 0.50 2640.0 15 5 20 52800.0 $3,000 $ 158,400,000.00 Total Length 4.40 23232 Total Cost (FY19) $ 8,276,188,800.00 Total Cost (FY20) $ 8,375,503,065.60 Total Cost $ 11,725,704,291.84 (FY20 with Contingency)

Design Concept 3 (Willoughby Bay and Naval Station Norfolk Sea Barrier) Sea Barrier Section Sea Barrier Sea Barrier Section Length Section Length Height above Avg Depth below Total Height Total Area Cost Fator Cost Category Section Start (mi) Section End (mi) (mi) (ft) MLLW (ft) MLLW (ft) (ft) (ft2) (FY19 USD) (FY19 USD) Static 0.00 0.30 0.30 1584.0 15 5 20 31680.0 $3,000 $ 95,040,000.00 AUX 0.30 1.05 0.75 3960.0 15 10 25 99000.0 $14,000 $ 1,386,000,000.00 Static 1.05 1.55 0.50 2640.0 15 5 20 52800.0 $3,000 $ 158,400,000.00 Static 1.55 1.95 0.40 2112.0 15 10 25 52800.0 $3,000 $ 158,400,000.00 NAV (Stowage) 1.95 2.08 0.13 686.4 15 30 45 30888.0 $19,000 $ 586,872,000.00 NAV (Gate) 2.08 2.32 0.24 1267.2 15 50 65 82368.0 $19,000 $ 1,564,992,000.00 NAV (Stowage) 2.32 2.45 0.13 686.4 15 50 65 44616.0 $19,000 $ 847,704,000.00 Static 2.45 3.05 0.60 3168.0 15 45 60 190080.0 $3,000 $ 570,240,000.00 AUX 3.05 3.55 0.50 2640.0 15 35 50 132000.0 $14,000 $ 1,848,000,000.00 Static 3.55 4.05 0.50 2640.0 15 20 35 92400.0 $3,000 $ 277,200,000.00 AUX 4.05 5.05 1.00 5280.0 15 15 30 158400.0 $14,000 $ 2,217,600,000.00 Static 5.05 5.55 0.50 2640.0 15 5 20 52800.0 $3,000 $ 158,400,000.00 Total Length 5.55 29304 Total Cost (FY19) $ 9,868,848,000.00 Total Cost (FY20) $ 9,987,274,176.00 Total Cost $ 13,982,183,846.40 (FY20 with Contingency) Design Concept 4 (Pinner Point and Norfolk Naval Shipyard Sea Barrier) Sea Barrier Section Sea Barrier Sea Barrier Section Length Section Length Height above Avg Depth below Total Height Total Area Cost Fator Cost Category Section Start (mi) Section End (mi) (mi) (ft) MLLW (ft) MLLW (ft) (ft) (ft2) (FY19 USD) (FY19 USD) Static 0.00 0.30 0.30 1584.0 15 10 25 39600.0 $3,000 $ 118,800,000.00 NAV (Stowage) 0.30 0.35 0.05 264.0 15 40 55 14520.0 $19,000 $ 275,880,000.00 NAV (Gate) 0.35 0.45 0.10 528.0 15 50 65 34320.0 $19,000 $ 652,080,000.00 NAV (Stowage) 0.45 0.50 0.05 264.0 15 50 65 17160.0 $19,000 $ 326,040,000.00 Static 0.50 0.55 0.05 264.0 15 10 25 6600.0 $3,000 $ 19,800,000.00 Total Length 0.55 2904 Total Cost (FY19) $ 1,392,600,000.00 Total Cost (FY20) $ 1,409,311,200.00 Total Cost $ 1,973,035,680.00 (FY20 with Contingency)

Design Concept 5 (Outer Sea Barrier: Hampton Roads Bridge Tunnel; Inner Sea Barrier: Pinner Point and Norfolk Naval Shipyard) Sea Barrier Section Sea Barrier Sea Barrier Section Length Section Length Height above Avg Depth below Total Height Total Area Cost Fator Cost Category Section Start (mi) Section End (mi) (mi) (ft) MLLW (ft) MLLW (ft) (ft) (ft2) (FY19 USD) (FY19 USD) Static 0.00 0.50 0.50 2640.0 15 5 20 52800.0 $3,000 $ 158,400,000.00 AUX 0.50 1.00 0.50 2640.0 15 5 20 52800.0 $14,000 $ 739,200,000.00 Static 1.00 1.36 0.36 1900.8 15 7 22 41817.6 $3,000 $ 125,452,800.00 AUX 1.36 1.56 0.20 1056.0 15 40 55 58080.0 $14,000 $ 813,120,000.00 NAV (Stowage) 1.56 1.69 0.13 686.4 15 50 65 44616.0 $19,000 $ 847,704,000.00 NAV (Gate) 1.69 1.93 0.24 1267.2 15 50 65 82368.0 $19,000 $ 1,564,992,000.00 NAV (Stowage) 1.93 2.06 0.13 686.4 15 50 65 44616.0 $19,000 $ 847,704,000.00 AUX 2.06 2.36 0.30 1584.0 15 55 70 110880.0 $14,000 $ 1,552,320,000.00 Static 2.36 2.80 0.44 2323.2 15 45 60 139392.0 $3,000 $ 418,176,000.00 Static 2.80 3.40 0.60 3168.0 15 10 25 79200.0 $3,000 $ 237,600,000.00 AUX 3.40 3.90 0.50 2640.0 15 7 22 58080.0 $14,000 $ 813,120,000.00 Static 3.90 4.40 0.50 2640.0 15 5 20 52800.0 $3,000 $ 158,400,000.00 Static 0.00 0.30 0.30 1584.0 15 10 25 39600.0 $3,000 $ 118,800,000.00 NAV (Stowage) 0.30 0.35 0.05 264.0 15 40 55 14520.0 $19,000 $ 275,880,000.00 NAV (Gate) 0.35 0.45 0.10 528.0 15 50 65 34320.0 $19,000 $ 652,080,000.00 NAV (Stowage) 0.45 0.50 0.05 264.0 15 50 65 17160.0 $19,000 $ 326,040,000.00 Static 0.50 0.55 0.05 264.0 15 10 25 6600.0 $3,000 $ 19,800,000.00 Total Length 4.95 26136 Total Cost (FY19) $ 9,668,788,800.00 Total Cost (FY20) $ 9,784,814,265.60 Total Cost $ 13,698,739,971.84 (FY20 with Contingency)

Design Concept 6 (Outer Sea Barrier: Willoughby Bay and Naval Station Norfolk; Inner Sea Barrier: Pinner Point and Norfolk Naval Shipyard) Sea Barrier Section Sea Barrier Sea Barrier Section Length Section Length Height above Avg Depth below Total Height Total Area Cost Fator Cost Category Section Start (mi) Section End (mi) (mi) (ft) MLLW (ft) MLLW (ft) (ft) (ft2) (FY19 USD) (FY19 USD) Static 0.00 0.30 0.30 1584.0 15 5 20 31680.0 $3,000 $ 95,040,000.00 AUX 0.30 1.05 0.75 3960.0 15 10 25 99000.0 $14,000 $ 1,386,000,000.00 Static 1.05 1.55 0.50 2640.0 15 5 20 52800.0 $3,000 $ 158,400,000.00 Static 1.55 1.95 0.40 2112.0 15 10 25 52800.0 $3,000 $ 158,400,000.00 NAV (Stowage) 1.95 2.08 0.13 686.4 15 30 45 30888.0 $19,000 $ 586,872,000.00 NAV (Gate) 2.08 2.32 0.24 1267.2 15 50 65 82368.0 $19,000 $ 1,564,992,000.00 NAV (Stowage) 2.32 2.45 0.13 686.4 15 50 65 44616.0 $19,000 $ 847,704,000.00 Static 2.45 3.05 0.60 3168.0 15 45 60 190080.0 $3,000 $ 570,240,000.00 AUX 3.05 3.55 0.50 2640.0 15 35 50 132000.0 $14,000 $ 1,848,000,000.00 Static 3.55 4.05 0.50 2640.0 15 20 35 92400.0 $3,000 $ 277,200,000.00 AUX 4.05 5.05 1.00 5280.0 15 15 30 158400.0 $14,000 $ 2,217,600,000.00 Static 5.05 5.55 0.50 2640.0 15 5 20 52800.0 $3,000 $ 158,400,000.00 Static 0.00 0.30 0.30 1584.0 15 10 25 39600.0 $3,000 $ 118,800,000.00 NAV (Stowage) 0.30 0.35 0.05 264.0 15 40 55 14520.0 $19,000 $ 275,880,000.00 NAV (Gate) 0.35 0.45 0.10 528.0 15 50 65 34320.0 $19,000 $ 652,080,000.00 NAV (Stowage) 0.45 0.50 0.05 264.0 15 50 65 17160.0 $19,000 $ 326,040,000.00 Static 0.50 0.55 0.05 264.0 15 10 25 6600.0 $3,000 $ 19,800,000.00 Total Length 6.10 32208 Total Cost (FY19) $ 11,261,448,000.00 Total Cost (FY20) $ 11,396,585,376.00 Total Cost $ 15,955,219,526.40 (FY20 with Contingency) THIS PAGE INTENTIONALLY LEFT BLANK

144 Appendix C

Shoreline Barrier Cost Model

The shoreline barrier cost model was established based on the data provided from multiple sources to include the USACE New York-New Jersey Harbor and Tributaries Feasibility Study, the USACE Norfolk Coastal Storm Risk Management Feasibility Study, the GCCPRD Texas Storm Surge Suppression Study, and a parametric analysis of pier and wharf construction reports from the Norfolk area. The NY-NJ Study cost factors outlined in Figure C-1 served as the baseline metrics for the shoreline barrier components. These values were compared to the data provided in the Norfolk Study in order to establish optimized cost factors as outlined in this appendix.

Figure C-1: Shoreline Infrastructure Cost Factors (FY19 USD/LF) [USACE New York District, 2019]

145 Shoreline Barrier Component Cost Factor Analysis Seawall (T-Wall) Cost Analysis Sluice Gate Cost Analysis Study ID Height (ft) Cost (FY18) Length (ft) Cost/LF Study ID No. of Gates Cost (FY18) Gate Size (ft) Cost/LF 1.1.1.1.3 8 $ 5,482,518.71 1900 $ 2,885.54 4.1.2.1.2 1 $ 1,506,897.23 30 $ 50,229.91 1.1.1.1.4 7 $ 10,536,671.92 3742 $ 2,815.79 6.1.2.2.1 1 $ 2,157,199.63 50 $ 43,143.99 3.1.1.1.2 8 $ 108,123.50 26 $ 4,158.60 7.1.3.2.1 1 $ 1,506,897.23 30 $ 50,229.91 3.1.1.1.4 7 $ 635,562.54 214 $ 2,969.92 13.1.2.2.2 1 $ 924,023.78 20 $ 46,201.19 5.1.1.1.3 10 $ 6,316,358.04 2045 $ 3,088.68 13.1.2.2.3 2 $ 4,850,485.91 60 $ 40,420.72 6.1.1.1.2 11 $ 11,057,255.84 3531 $ 3,131.48 14.1.3.2.2 8 $ 7,392,190.22 20 $ 46,201.19 7.1.1.1.3 7 $ 23,226,954.73 8302 $ 2,797.75 Norfolk Study Average Cost/LF (Adjusted for FY19) $ 46,900.43 8.1.1.1.1 9 $ 7,478,954.73 2559 $ 2,922.61 NY-NJ Study Comparison: Limited Access Flood Gate (FY19) $ 30,000.00 9.1.1.1.4 12$ 4,220,700.69 1314 $ 3,212.10 Note: The number of gates for 13.1.2.2.3 was changed from 1 to 2 to match the design 10.1.1.1.2 8 $ 2,240,217.72 772 $ 2,901.84 descriptions. As listed in the cost data with one gate, the cost per linear foot was 80K. 11.1.1.1.2 11 $ 10,294,005.59 3282 $ 3,136.50 13.1.1.1.2 9 $ 11,382,424.97 3901 $ 2,917.82 Miter Gate Cost Analysis 14.1.1.1.3 8 $ 12,223,252.18 4277 $ 2,857.90 Study ID No. of Gates Gate Cost (FY18) Gate Size (ft) Cost/LF 14.1.1.1.4 7 $ 12,655,804.79 4510 $ 2,806.17 1.1.3.2.3 1 $ 7,342,678.73 65 $ 59,696.58 Norfolk Study Average Cost/LF (Adjusted for FY19) $ 3,010.47 5.1.3.2.1 2$ 7,808,804.28 65 $ 63,486.21 NY-NJ Study Comparison: Unlimited Access Seawall (FY19) $ 3,000.00 3.1.2.1.2 3$ 8,577,671.16 70 $ 67,013.06 Note: T-Wall 3.1.1.1.2 was identified as an outlier as shown in red, and removed from the 3.1.2.1.2 3 $10,259,567.46 70 $ 80,152.87 average. A comparison of 8ft T-Wall component costs is shown below. 3.1.2.1.2 3 $11,941,463.77 70 $ 93,292.69 Norfolk Study Shallow Water Average Cost/LF (Adjusted for FY19) $ 74,037.39 Component Cost/Unit Comparison for 8ft T-Walls NY-NJ Study Comparison: Very Limited Access Flood Gate (FY19) $ 75,000.00 Component 1.1.1.1.3 3.1.1.1.2 10.1.1.1.2 14.1.1.1.3 Study ID No. of Gates Gate Cost (FY18) Gate Size (ft) Cost/LF T-Wall $ 2,885.54 $ 4,158.60 $ 2,901.84 $ 2,857.90 13.1.2.2.1 1 $ 4,469,038.75 60 $ 37,873.21 Excavation $ 23.92 $ 23.45 $ 23.94 $ 23.92 14.1.3.2.1 6 $ 4,841,458.65 65 $ 39,361.45 Fill $ 9.42 $ 9.42 $ 9.42 $ 9.42 Norfolk Study Tidal Average Cost/LF (Adjusted for FY19) $ 39,312.44 Concrete $ 101.44 $ 102.22 $ 100.55 $ 104.35 NY-NJ Study Comparison: Limited Access Flood Gate (FY19) $ 30,000.00 Piles $ 55.69 $ 112.74 $ 57.18 $ 55.11 Note: Cost per linear foot averages were established for shallow water and tidal miter gates Bentonite $ 1,028.75 $ 998.61 $ 1,028.54 $ 1,028.26 to account for the differences in overall structure height. Dewatering $ 1,245.62 $ 1,245.62 $ 1,245.62 $ 1,245.62 Note: An analysis of the component costs of all 8ft T-Walls identified the cause of the cost per Cost/Area Analysis for Miter Gates linear foot deviation as shown in red. Without a clear reason for the drastic difference in Study ID No. of Gates Gate Length (ft) Total Height (ft) Gate Area (ft2) these cost per units, the T-Wall was removed from the average. 1.1.3.2.3 1 65 23.5 1528 5.1.3.2.1 2 65 25.0 1625 Floodwall (Combo-Wall) Cost Analysis 3.1.2.1.2 3 70 25.5 1785 Study ID Avg Depth (ft) Cost (FY18) Length (ft) Cost/LF 3.1.2.1.2 3 70 30.5 2135 1.1.1.1.2 6 $ 1,094,509.21 114 $ 9,600.96 3.1.2.1.2 3 70 35.5 2485 3.1.1.1.3 4 $ 57,973,753.10 6634 $ 8,738.88 13.1.2.2.1 1 60 15.5 930 5.1.1.1.2 8 $ 5,330,992.49 535 $ 9,964.47 14.1.3.2.1 6 65 15.5 1008 14.1.1.1.2 1$ 11,354,486.60 1291 $ 8,795.11 Total Area (ft2) Area Ratio Total Cost (FY18) Cost/Gate (FY18) Cost/SF (FY18) Norfolk Study Average Cost/LF (Adjusted for FY19) $ 9,441.80 1528 1.00 $ 7,342,678.73 $ 7,342,678.73 $ 4,806.99 NY-NJ Study Comparison: Limited Access Floodwall (FY19) $ 11,250.00 3250 0.50 $ 15,617,608.55 $ 7,808,804.28 $ 4,805.42 Note: The length of Combo wall 5.1.1.1.2 was estimated based on design drawings due to an 0.09 $ 8,577,671.16 $ 4,805.42 error in the cost data with the unit of measurement listed as EA vs LF. 192150.11 $ 92,336,107.17 $ 10,259,567.46 $ 4,805.42 0.13 $ 11,941,463.77 $ 4,805.42 Sector Gate Cost Analysis 930 1.00 $ 4,469,038.75 $ 4,469,038.75 $ 4,805.42 Study Avg Depth (ft) Cost (FY18) Length (ft) Cost/LF 6045 0.17 $ 29,048,751.90 $ 4,841,458.65 $ 4,805.42 USACE Norfolk 10 $ 95,251,285.11 150 $ 635,008.57 Note: The above analysis was conducted to confirm a consistent cost per square foot of GCCPRD Houston 60 $786,505,366.80 1200 $ 655,421.14 structure. For detailed cost analyses, the cost per area metric would provide greater Sector Gate Average Cost/LF (Adjusted for FY19) $ 645,214.85 granularity for structures of varying dimensions. In this case, the cost per linear foot metric Note: USACE Norfolk Study and GCCPRD Texas Coastal Study utilized to establish average. was used to promote consistency with the NY-NJ study shoreline cost factors.

Cost Factor Selections Barrier Category NY-NJ Study Access Characterization NY-NJ Study CF Norfolk Study CF Selected CF Cost Factor Analysis and Selection Notes Tidal Combo Wall Limited Floodwall $ 11,250.00 $ 9,441.80 $ 10,000.00 Rounded average of the Norfolk and NY-NJ Study cost factors Tidal Sluice Gate Limited to Very Limited Flood Gate $ 52,500.00 $ 46,900.43 $ 50,000.00 Rounded average of the Norfolk and NY-NJ Study cost factors Tidal Miter Gate Very Limited Flood Gate $ 75,000.00 $ 74,037.39 $ 75,000.00 Rounded average of the Norfolk and NY-NJ Study cost factors Tidal Sector Gate N/A - $ 645,214.85 $ 645,000.00 Rounded average of the Norfolk Study and GCCPRD TX Study Shoreline Seawall: Unlimited Seawall $ 3,000.00 $ 3,010.47 $ 3,000.00 Established based on the NY-NJ Study unlimited and limited access cost Low, Med, High Unlimited to Limited Seawall $ 3,750.00 - $ 4,000.00 metrics for a seawall. The unlimited to limited access seawall metric was Development Limited Seawall $ 4,500.00 - $ 4,500.00 extrapolated and rounded to establish a tier of cost factors. Promenade/Quay: Unlimited Elevated Promenade $ 7,500.00 - $ 7,500.00 Established based on the NY-NJ Study unlimited and limited access cost Low, Med, High Unlimted to Limited Promenade $ 11,250.00 - $ 12,000.00 metrics for an elevated promenade. The middle metric was extrapolated Development Limited Elevated Promenade $ 15,000.00 - $ 15,000.00 and rounded to established a tier of cost factors. Pier/Wharf: N/A - - $ 10,000.00 Selected based on the analysis outlined on the following page. A high Small, Medium, N/A - - $ 15,000.00 pier and wharf cost was established. Based on this value, a tier of Large Scale N/A - $ 30,000.00 $ 30,000.00 nominal cost factors was created for large, medium and small scale piers Pier and Wharf Parametric Cost Analysis

Contract Amount Structure Length Year Project Type Location Contractor Cost/LF Adjusted Cost/LF (FY19 USD) (ft) 2000 Two-Deck, Military NS Norfolk Pier 2 & 6 Skanska $114,000,000.00 3000 $ 38,000.00 $ 28,500.00 2003 Three-Deck, Shipyard NN Shipbuilding Pier 3 WF Magann $ 90,000,000.00 1040 $ 86,538.46 $ 28,846.15 2004 One-Deck, Shipyard BAE Shipyard Pier 4 WF Magann $ 11,500,000.00 700 $ 16,428.57 $ 20,535.71 2005 Two-Deck, Military NS Norfolk Pier 7 & 11 McLean $125,000,000.00 3100 $ 40,322.58 $ 30,241.94 2007 One-Deck, Shipyard MHI Shipyard Pier WF Magann $ 28,000,000.00 1200 $ 23,333.33 $ 23,333.33 2014 One-Deck, Military Fuel Craney Island Fuel Pier McLean $ 31,000,000.00 920 $ 33,695.65 $ 33,695.65

Contract Amount Structure Length Year Project Type Location Contractor Cost/LF Adjusted Cost/LF (FY19 USD) (ft) 2002 Container Terminal Wharf Port of Virginia: NIT Skanska $112,500,000.00 4230 $ 26,595.74 - 2006 Container Terminal Wharf Port of Virginia: VIG Weeks Marine $127,000,000.00 3750 $ 33,866.67 - 2010 Shipyard Wharf BAE Shipyard WF Magann $ 12,500,000.00 480 $ 26,041.67 2010 Shipyard Wharf Naval Shipyard: NNSY Weeks Marine $ 25,000,000.00 800 $ 31,250.00 -

Structure Type Average Cost/LF Rounded Cost/LF Cost Adjustment Notes Military Pier $ 30,812.53 30K NSN and NNSB multi-deck piers adjusted to estimate single-deck pier costs. Shipyard Pier $ 24,238.40 25K BAE pier built on top of old pier. Cost adjusted to account for usual demo Wharf $ 29,438.52 30K cost. Contract at NNSY was multi-part; Adjusted to estimate wharf cost only

Data Sources McLean: https://mcleancontracting.com/portfolio Weeks Marine: https://www.weeksmarine.com/projects W.F. Magann Corporation: https://wfmagann.com/project-gallery/ Skanska: https://www.usa.skanska.com/what-we-deliver/projects/ MILCON Contract Data: https://www.secnav.navy.mil/fmc/fmb/Documents/19pres/MCON_Book.pdf NAVFAC Contract Data: https://www.navfac.navy.mil/atlantic/news/navfac-atlantic-contracts/

McLean: NSN Pier 11 McLean: NSN Pier 7 McLean: Craney Island Fuel Pier

W.F. Magann: BAE Pier 4 W.F. Magann: BAE North Wharf W.F. Magann: NN Shipbuilding Pier 3

Skanska: NIT Wharf Weeks Marine: NNSY Wharf Weeks Marine: VIG Wharf THIS PAGE INTENTIONALLY LEFT BLANK

148 Appendix D

Shoreline Barrier Cost Analysis

Appendix D outlines the shoreline infrastructure and hybrid shoreline barrier cost analyses. The established cost factors are shown in Figure D-1 and D-2.

Figure D-1: Shoreline Analysis One: Shoreline Infrastructure

Figure D-2: Shoreline Analysis Two: Shoreline Hybrid Barrier

149 Shoreline Infrastructure Analysis Total Structure Length: 795 miles

Shoreline Barrier Cost Estimate (City of Norfolk, Virginia) For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 1 ($3000/LF) Shoreline Barrier Type 2 ($7500/LF) River System/Waterway Shoreline Agriculture (mi) Bare (mi) Forest (mi) Grass (mi) Shrub (mi) Adj Total (mi) Barrier Cost Paved (mi) Adj Total (mi) Barrier Cost Willoughby Bay 90% 0 0 0 0 0 0.00 $ - 1 0.90 $ 35,640,000.00 Hampton Roads 100% 0 0 0 0 0 0.00 $ - 0 0.00 $ - Lafayette River 95% 0 0 1 2 0 2.85 $ 45,144,000.00 2 1.90 $ 75,240,000.00 Elizabeth River 91% 0 0 0 2 0 1.82 $ 28,828,800.00 0 0.00 $ - Eastern Elizabeth River 88% 0 0 0 2 0 1.76$ 27,878,400.00 4 3.52$ 139,392,000.00 & Tributaries Southern Elizabeth River 100% 0 0 0 0 0 0.00$ - 0 0.00$ - & Tributaries Totals 0 0 1 6 0 6.43 $ 101,851,200.00 7 6.32 $ 250,272,000.00

Low-Lying Shoreline Barrier Type 3 ($4500/LF) Shoreline Barrier Type 4 ($15000/LF) River System/Waterway Shoreline Barrier System Costs Shoreline Residential (mi) Commericial (mi) Adj Total (mi) Barrier Cost Industrial (mi) Military (mi) Adj Total (mi) Barrier Cost Willoughby Bay 90% 2 1 2.7 $ 64,152,000.00 0 5 4.5 $ 356,400,000.00 Barrier Type 1 $ 101,851,200.00 Hampton Roads 100% 0 0 0 $ - 2 4 6 $ 475,200,000.00 Lafayette River 95% 51 4 52.25 $ 1,241,460,000.00 1 0 0.95 $ 75,240,000.00 Barrier Type 2 $ 250,272,000.00 Elizabeth River 91% 2 3 4.55 $ 108,108,000.00 4 0 3.64 $ 288,288,000.00 Eastern Elizabeth River 88% 22 7 25.52$ 606,355,200.00 5 0 4.4 Barrier Type 3 $ 2,020,075,200.00 & Tributaries $ 348,480,000.00 Southern Elizabeth River 100% 0 0 0$ - 3 0 3 Barrier Type 4 $ 1,781,208,000.00 & Tributaries $ 237,600,000.00 Totals 77 15 85.02 $2,020,075,200.00 15 9 22.49 $1,781,208,000.00 Total System Cost $4,153,406,400.00

Source: VIMS Source: VIMS

Shoreline Barrier Cost Estimate (City of Portsmouth, Virginia) For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 1 ($3000/LF) Shoreline Barrier Type 2 ($7500/LF) River System/Waterway Shoreline Agriculture (mi) Bare (mi) Forest (mi) Grass (mi) Shrub (mi) Adj Total (mi) Barrier Cost Paved (mi) Adj Total (mi) Barrier Cost Hampton Roads 100% 0 0 0 0 0 0.00 $ - 0 0.00 $ - Hoffler Creek 100% 0 0 1 0 0 1.00 $ 15,840,000.00 0 0.00 $ - Elizabeth River 96% 0 0 2 3 0 4.79 $ 75,900,000.00 2 1.92 $ 75,900,000.00 Western Elizabeth River 98% 0 0 0 2 0 1.95$ 30,943,255.81 1 0.98$ 38,679,069.77 & Tributaries Southern Elizabeth River 93% 0 0 0 2 0 1.86$ 29,417,142.86 0 0.00$ - & Tributaries Totals 0 0 3 7 0 9.60 $ 152,100,398.67 3 2.89 $ 114,579,069.77

Low-Lying Shoreline Barrier Type 3 ($4500/LF) Shoreline Barrier Type 4 ($15000/LF) River System/Waterway Shoreline Barrier System Costs Shoreline Residential (mi) Commericial (mi) Adj Total (mi) Barrier Cost Industrial (mi) Military (mi) Adj Total (mi) Barrier Cost Hampton Roads 100% 1 0 1.00 $ 23,760,000.00 6 1 7.00 $ 554,400,000.00 Barrier Type 1 $ 152,100,398.67 Hoffler Creek 100% 6 0 6.00 $ 142,560,000.00 0 0 0.00 $ - Barrier Type 2 $ 114,579,069.77 Elizabeth River 96% 4 9 12.48 $ 296,524,800.00 2 3 4.80 $ 380,160,000.00 Western Elizabeth River 98% 37 3 39.20$ 931,392,000.00 0 0 0.00 Barrier Type 3 $ 1,504,720,800.00 & Tributaries $ - Southern Elizabeth River 93% 3 2 4.65$ 110,484,000.00 1 5 5.58 Barrier Type 4 $ 1,376,496,000.00 & Tributaries $ 441,936,000.00 Totals 51 14 63.33 $1,504,720,800.00 9 9 17.38 $1,376,496,000.00 Total System Cost $3,147,896,268.44

Source: VIMS Source: VIMS Shoreline Barrier Cost Estimate (City of Chesapeake, Virginia) For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 1 ($3000/LF) Shoreline Barrier Type 2 ($7500/LF) River System/Waterway Shoreline Agriculture (mi) Bare (mi) Forest (mi) Grass (mi) Shrub (mi) Adj Total (mi) Barrier Cost Paved (mi) Adj Total (mi) Barrier Cost Southern Elizabeth River 99% 3 1 21 14 1 39.74$ 629,431,578.95 17 16.89$ 668,771,052.63 & Tributaries Eastern Elizabeth River 100% 0 0 0 0 0 0.00$ - 0 0.00$ - & Tributaries Western Elizabeth River 100% 1 0 1 4 0 6.00$ 95,040,000.00 3 3.00$ 118,800,000.00 & Tributaries Totals 4 1 22 18 1 45.74 $ 724,471,578.95 20 19.89 $ 787,571,052.63

Low-Lying Shoreline Barrier Type 3 ($4500/LF) Shoreline Barrier Type 4 ($15000/LF) River System/Waterway Shoreline Barrier System Costs Shoreline Residential (mi) Commericial (mi) Adj Total (mi) Barrier Cost Industrial (mi) Military (mi) Adj Total (mi) Barrier Cost Southern Elizabeth River 99% 55 15 69.30$ 1,646,568,000.00 18 3 20.79 Barrier Type 1 & 2 $ 1,512,042,631.58 & Tributaries $ 1,646,568,000.00 Eastern Elizabeth River 100% 17 0 17.00$ 403,920,000.00 0 0 0.00 Barrier Type 3 $ 2,953,368,000.00 & Tributaries $ - Western Elizabeth River 100% 37 1 38.00$ 902,880,000.00 0 0 0.00 Barrier Type 4 $ 1,646,568,000.00 & Tributaries $ - Totals 109 16 124.30 $2,953,368,000.00 18 3 20.79 $1,646,568,000.00 Total System Cost $6,111,978,631.58

Source: VIMS Source: VIMS

Shoreline Barrier Cost Estimate (City of Virginia Beach, Virginia) For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 1 ($3000/LF) Shoreline Barrier Type 2 ($7500/LF) River System/Waterway Shoreline Agriculture (mi) Bare (mi) Forest (mi) Grass (mi) Shrub (mi) Adj Total (mi) Barrier Cost Paved (mi) Adj Total (mi) Barrier Cost Eastern Elizabeth River 100% 0 0 3 1 1 5.00$ 79,200,000.00 1 1.00$ 39,600,000.00 & Tributaries Totals 0 0 3 1 1 5.00 $ 79,200,000.00 1 1.00 $ 39,600,000.00

Source: VIMS Source: VIMS

Shoreline Barrier Cost Estimate (City of Hampton, Virginia) For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 1 ($3000/LF) Shoreline Barrier Type 2 ($7500/LF) River System/Waterway Shoreline Agriculture (mi) Bare (mi) Forest (mi) Grass (mi) Shrub (mi) Adj Total (mi) Barrier Cost Paved (mi) Adj Total (mi) Barrier Cost Hampton Roads 85% 0 0 0 2 0 1.69 $ 26,806,153.85 2 1.69 $ 67,015,384.62 Totals 0 0 0 2 0 1.69 $ 26,806,153.85 2 1.69 $ 67,015,384.62

Source: VIMS Source: VIMS Shoreline Barrier Cost Estimate (City of Newport News, Virginia) Source: VIMS For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 2 ($7500/LF) Shoreline Barrier Type 3 ($4500/LF) River System/Waterway Shoreline Paved (mi) Adj Total (mi) Barrier Cost Residential (mi) Commericial (mi) Adj Total (mi) Barrier Cost James River 86% 6 5.14 $203,657,142.86 9 3 10.29 $ 244,388,571.43 Warwick River 87% 2 1.74 $ 69,069,767.44 46 2 41.86 $ 994,604,651.16 Totals 8 6.89 $272,726,910.30 55 5 52.15 $ 1,238,993,222.59

Low-Lying Shoreline Barrier Type 4 ($15000/LF) Shoreline Barrier System Costs River System/Waterway Shoreline Industrial (mi) Military (mi) Adj Total (mi) Barrier Cost Barrier Type 2 Barrier Type 3 Barrier Type 4 James River & Tributaries 86% 7 4 9.46 $ 749,232,000.00 $ 272,726,910.30 $ 1,238,993,222.59 $ 818,136,000.00 Warwick River 87% 0 1 0.87 $ 68,904,000.00 Totals 7 5 10.33 $ 818,136,000.00 Total System Cost $ 2,329,856,132.89

Shoreline Barrier Cost Estimate (City of Suffolk, Virginia) Source: VIMS For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 2 ($7500/LF) Shoreline Barrier Type 3 ($4500/LF) River System/Waterway Shoreline Paved (mi) Adj Total (mi) Barrier Cost Residential (mi) Commericial (mi) Adj Total (mi) Barrier Cost James River & Tributaries 92% 1 0.92 $ 36,432,000.00 12 0 11.04 $ 262,310,400.00 Nansemond River 84% 3 2.53 $100,200,000.00 41 3 37.11 $ 881,760,000.00 Totals 4 3.45 $136,632,000.00 53 3 48.15 $ 1,144,070,400.00

Shoreline Barrier Cost Estimate (Isle of Wight County, Virginia) Source: VIMS For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 2 ($7500/LF) Shoreline Barrier Type 3 ($4500/LF) River System/Waterway Shoreline Paved (mi) Adj Total (mi) Barrier Cost Residential (mi) Commericial (mi) Adj Total (mi) Barrier Cost James River & Tributaries 86% 5 4.28 $169,400,000.00 36 1 31.66 $ 752,136,000.00 Pagan River 78% 7 5.47 $216,757,894.74 47 3 39.10 $ 928,962,406.02 Totals 12 9.75 $386,157,894.74 83 4 70.75 $ 1,681,098,406.02

Shoreline Barrier Cost Estimate (Surry County, Virginia) Source: VIMS For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 2 ($7500/LF) Shoreline Barrier Type 3 ($4500/LF) River System/Waterway Shoreline Paved (mi) Adj Total (mi) Barrier Cost Residential (mi) Commericial (mi) Adj Total (mi) Barrier Cost James River & Tributaries 85% 2 1.71 $ 67,574,311.93 14 1 12.80 $ 304,084,403.67 Totals 2 1.71 $ 67,574,311.93 14 1 12.80 $ 304,084,403.67

Low-Lying Shoreline Barrier Type 4 ($15000/LF) Shoreline Barrier System Costs River System/Waterway Shoreline Industrial (mi) Military (mi) Adj Total (mi) Barrier Cost Barrier Type 2 Barrier Type 3 Barrier Type 4 James River & Tributaries 85% 1 0 0.85 $ 67,320,000.00 $ 67,574,311.93 $ 304,084,403.67 $ 67,320,000.00 Totals 1 0 0.85 $ 67,320,000.00 Total System Cost $ 438,978,715.60

Shoreline Barrier Cost Estimate (Prince George County and City of Hopewell, Virginia) Source: VIMS For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 2 ($7500/LF) Shoreline Barrier Type 3 ($4500/LF) River System/Waterway Shoreline Paved (mi) Adj Total (mi) Barrier Cost Residential (mi) Commericial (mi) Adj Total (mi) Barrier Cost James River & Tributaries 100% 0 0.00 $ - 9 1 10.00 $ 237,600,000.00 Appomattox River 92% 0 0.00 $ - 7 2 8.31 $ 197,390,769.23 Totals 0 0.00 $ - 16 3 18.31 $ 434,990,769.23

Low-Lying Shoreline Barrier Type 4 ($15000/LF) Shoreline Barrier System Costs River System/Waterway Shoreline Industrial (mi) Military (mi) Adj Total (mi) Barrier Cost Barrier Type 2 Barrier Type 3 Barrier Type 4 James River & Tributaries 100% 6 0 6.00 $ 475,200,000.00 $ - $ 434,990,769.23 $ 693,792,000.00 Appomattox River 92% 3 0 2.76 $ 218,592,000.00 Totals 9 0 8.76 $ 693,792,000.00 Total System Cost $ 1,128,782,769.23

Shoreline Barrier Cost Estimate (Chesterfield County, City of Pertersburg, City of Colonial Heights and City of Richmond, Virginia) Source: VIMS For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 2 ($7500/LF) Shoreline Barrier Type 3 ($4500/LF) River System/Waterway Shoreline Paved (mi) Adj Total (mi) Barrier Cost Residential (mi) Commericial (mi) Adj Total (mi) Barrier Cost James River & Tributaries 91% 6 5.47 $216,546,835.44 4 5 8.20 $ 194,892,151.90 Appomattox River 95% 3 2.86 $113,337,931.03 9 5 13.36 $ 317,346,206.90 Totals 9 8.33 $329,884,766.48 13 10 21.56 $ 512,238,358.80

Low-Lying Shoreline Barrier Type 4 ($15000/LF) Shoreline Barrier System Costs River System/Waterway Shoreline Industrial (mi) Military (mi) Adj Total (mi) Barrier Cost Barrier Type 2 Barrier Type 3 Barrier Type 4 James River & Tributaries 100% 5 0 5.00 $ 396,000,000.00 $ 329,884,766.48 $ 512,238,358.80 $ 396,000,000.00 Appomattox River 92% 0 0 0.00 $ - Totals 5 0 5.00 $ 396,000,000.00 Total System Cost $ 1,238,123,125.27

Shoreline Barrier Cost Estimate (Henrico County, Virginia) Source: VIMS For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 2 ($7500/LF) Shoreline Barrier Type 3 ($4500/LF) River System/Waterway Shoreline Paved (mi) Adj Total (mi) Barrier Cost Residential (mi) Commericial (mi) Adj Total (mi) Barrier Cost James River & Tributaries 89% 0 0.00 $ - 4 1 4.43 $ 105,222,857.14 Totals 0 0.00 $ - 4 1 4.43 $ 105,222,857.14

Low-Lying Shoreline Barrier Type 4 ($15000/LF) Shoreline Barrier System Costs River System/Waterway Shoreline Industrial (mi) Military (mi) Adj Total (mi) Barrier Cost Barrier Type 2 Barrier Type 3 Barrier Type 4 James River & Tributaries 89% 0 0 0.00 $ - $ - $ 105,222,857.14 $ - Totals 0 0 0.00 $ - Total System Cost $ 105,222,857.14 Shoreline Barrier Cost Estimate (New Kent County, Virginia) Source: VIMS For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 2 ($7500/LF) Shoreline Barrier Type 3 ($4500/LF) River System/Waterway Shoreline Paved (mi) Adj Total (mi) Barrier Cost Residential (mi) Commericial (mi) Adj Total (mi) Barrier Cost Chickahominy River 83% 2 1.67 $ 66,000,000.00 13 1 11.67 $ 277,200,000.00 Totals 2 1.67 $ 66,000,000.00 13 1 11.67 $ 277,200,000.00

Shoreline Barrier Cost Estimate (Charles City County, Virginia) Source: VIMS For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 2 ($7500/LF) Shoreline Barrier Type 3 ($4500/LF) River System/Waterway Shoreline Paved (mi) Adj Total (mi) Barrier Cost Residential (mi) Commericial (mi) Adj Total (mi) Barrier Cost James River & Tributaries 86% 0 0.00 $ - 4 0 3.46 $ 82,153,220.34 Chickahominy River 79% 0 0.00 $ - 4 0 3.17 $ 75,376,551.72 Totals 0 0.00 $ - 8 0 6.63 $ 157,529,772.06

Shoreline Barrier Cost Estimate (James City County and City of Williamsburg, Virginia) Source: VIMS For low-lying shoreline (0-5ft above MSL) within the protection zone of Sea Barrier Concept Design Five Low-Lying Shoreline Barrier Type 2 ($7500/LF) Shoreline Barrier Type 3 ($4500/LF) River System/Waterway Shoreline Paved (mi) Adj Total (mi) Barrier Cost Residential (mi) Commericial (mi) Adj Total (mi) Barrier Cost James River & Tributaries 77% 1 0.77 $ 30,589,221.56 30 1 23.95 $ 568,959,520.96 Chickahominy River 67% 2 1.34 $ 52,938,947.37 13 0 8.69 $ 206,461,894.74 Totals 3 2.11 $ 83,528,168.93 43 1 32.64 $ 775,421,415.69

Low-Lying Shoreline Barrier Type 4 ($15000/LF) Shoreline Barrier System Costs River System/Waterway Shoreline Industrial (mi) Military (mi) Adj Total (mi) Barrier Cost Barrier Type 2 Barrier Type 3 Barrier Type 4 James River & Tributaries 77% 0 0 0.00 $ - $ 83,528,168.93 $ 775,421,415.69 $ - Chickahominy River 67% 0 0 0.00 $ - Totals 0 0 0.00 $ - Total System Cost $ 858,949,584.62

City/County Primary Waterways Estimated Shoreline Barrier Cost Barrier Length (mi) Shoreline and Sea Barrier Comparison City of Norfolk Elizabeth River, Lafayette River $ 4,153,406,400.00 120 Shoreline City of Portsmouth Elizabeth River, Hampton Roads $ 3,147,896,268.44 93 Infrastructure $ 24,122,812,188.36 City of Chesapeake Elizabeth River $ 6,111,978,631.58 211 Baseline Cost City of Virginia Beach Elizabeth River $ 546,480,000.00 24 City of Hampton Hampton Roads $ 214,449,230.77 8 Shoreline City of Newport News James River, Warwick River $ 2,329,856,132.89 69 Infrastructure $ 34,254,393,307.46 City of Suffolk James River, Nansemond River $ 1,280,702,400.00 52 Adjusted Cost Isle of Wight County James River, Pagan River $ 2,067,256,300.75 81 (40% Contingency; FY20) Surry County James River $ 438,978,715.60 15 Prince George County James River, Appomattox River $ 1,128,782,769.23 27 Sea Barrier System $ 13,698,739,971.84 Chesterfield County James River, Appomattox River $ 1,238,123,125.27 35 Cost (Concept 5) Henrico County James River $ 105,222,857.14 4 New Kent County Chickahominy River $ 343,200,000.00 13 푩푪푹= Charles City County James River, Chickahominy River $ 157,529,772.06 7 푺푳푩 푪풐풔풕 − 푺푩 푪풐풔풕 1.50 James City County James River, Chickahominy River $ 858,949,584.62 35 푺푩 푪풐풔풕 Shoreline Barrier System Totals $ 24,122,812,188.36 795

Source: VIMS Source: VIMS

Virginia Shoreline Data and Imagery Source: Virginia Institute of Marine Science (VIMS) Center for Coastal Resources Management. https://www.vims.edu/ccrm/ccrmp/index.php Hybrid Shoreline Barrier Analysis Total Structure Length: 38.3 miles (Excluding Piers) Tidal Combo Wall ($10K/LF) Tidal Sluice Gates ($50K/LF) Tidal Miter Gates ($75K/LF) Section NR Length (ft) Cost Gate NR Length (ft) Cost Gate NR Length (ft) Cost 1 100 $ 1,000,000.00 1 30 $ 1,500,000.00 1 70 $ 5,250,000.00 2 140 $ 1,400,000.00 2 30 $ 1,500,000.00 2 70 $ 5,250,000.00 3 50 $ 500,000.00 3 20 $ 1,000,000.00 3 50 $ 3,750,000.00 4 890 $ 8,900,000.00 4 30 $ 1,500,000.00 4 70 $ 5,250,000.00 5 415 $ 4,150,000.00 5 30 $ 1,500,000.00 5 70 $ 5,250,000.00 6 285 $ 2,850,000.00 6 20 $ 1,000,000.00 6 70 $ 5,250,000.00 7 410 $ 4,100,000.00 7 15 $ 750,000.00 7 70 $ 5,250,000.00 8 195 $ 1,950,000.00 8 15 $ 750,000.00 8 70 $ 5,250,000.00 9 175 $ 1,750,000.00 9 15 $ 750,000.00 9 70 $ 5,250,000.00 10 175 $ 1,750,000.00 10 15 $ 750,000.00 10 70 $ 5,250,000.00 11 500 $ 5,000,000.00 11 15 $ 750,000.00 11 70 $ 5,250,000.00 12 500 $ 5,000,000.00 12 15 $ 750,000.00 12 65 $ 4,875,000.00 13 230 $ 2,300,000.00 13 15 $ 750,000.00 13 65 $ 4,875,000.00 14 440 $ 4,400,000.00 14 30 $ 1,500,000.00 14 65 $ 4,875,000.00 15 130 $ 1,300,000.00 15 15 $ 750,000.00 15 65 $ 4,875,000.00 16 355 $ 3,550,000.00 16 20 $ 1,000,000.00 16 70 $ 5,250,000.00 17 280 $ 2,800,000.00 17 20 $ 1,000,000.00 17 70 $ 5,250,000.00 18 70 $ 700,000.00 18 30 $ 1,500,000.00 18 50 $ 3,750,000.00 19 55 $ 550,000.00 19 30 $ 1,500,000.00 19 50 $ 3,750,000.00 20 170 $ 1,700,000.00 20 15 $ 750,000.00 20 70 $ 5,250,000.00 21 380 $ 3,800,000.00 21 20 $ 1,000,000.00 21 70 $ 5,250,000.00 22 380 $ 3,800,000.00 22 30 $ 1,500,000.00 22 70 $ 5,250,000.00 23 30 $ 300,000.00 Total 475 $ 23,750,000.00 23 70 $ 5,250,000.00 24 155 $ 1,550,000.00 24 70 $ 5,250,000.00 25 130 $ 1,300,000.00 Tidal Sector Gates ($645K/LF) 25 70 $ 5,250,000.00 26 130 $ 1,300,000.00 Gate NR Length (ft) Cost 26 70 $ 5,250,000.00 27 260 $ 2,600,000.00 1 120 $ 77,400,000.00 27 70 $ 5,250,000.00 28 130 $ 1,300,000.00 2 150 $ 96,750,000.00 28 70 $ 5,250,000.00 Total 7160 $ 71,600,000.00 Total 270 $ 174,150,000.00 29 70 $ 5,250,000.00 30 70 $ 5,250,000.00 31 70 $ 5,250,000.00 32 70 $ 5,250,000.00 33 70 $ 5,250,000.00 34 70 $ 5,250,000.00 Total 2300$ 172,500,000.00 Seawall: Low Density Development ($3,000/LF) Seawall: Medium Density Development ($4,000/LF) Seawall: High Density Development ($4,500/LF) Property Total Length (ft) Total Cost Property Length (ft) Cost Property Length (ft) Cost N/A 81219 $ 243,657,000.00 P28 150 $ 600,000.00 P27 1250 $ 5,625,000.00 P30 800 $ 3,200,000.00 P32 500 $ 2,250,000.00 Seawall: Medium Density Development ($4,000/LF) P33 1000 $ 4,000,000.00 P35 600 $ 2,700,000.00 Property Length (ft) Cost P36 825 $ 3,300,000.00 P37 500 $ 2,250,000.00 P1 250 $ 1,000,000.00 P43 6500 $ 26,000,000.00 P38 1200 $ 5,400,000.00 P2 1250 $ 5,000,000.00 P44 775 $ 3,100,000.00 P39 225 $ 1,012,500.00 P5 1600 $ 6,400,000.00 P47 1850 $ 7,400,000.00 P42 700 $ 3,150,000.00 P6 2000 $ 8,000,000.00 P49 1000 $ 4,000,000.00 P45 950 $ 4,275,000.00 P7 250 $ 1,000,000.00 P55 350 $ 1,400,000.00 P46 3000 $ 13,500,000.00 P8 200 $ 800,000.00 P57 1000 $ 4,000,000.00 P47 1750 $ 7,875,000.00 P10 400 $ 1,600,000.00 P58 1000 $ 4,000,000.00 P59 500 $ 2,250,000.00 P14 250 $ 1,000,000.00 P59 1500 $ 6,000,000.00 P67 500 $ 2,250,000.00 P15 1000 $ 4,000,000.00 P60 1225 $ 4,900,000.00 P68 500 $ 2,250,000.00 P17 800 $ 3,200,000.00 P61 600 $ 2,400,000.00 P70 1500 $ 6,750,000.00 P19 1000 $ 4,000,000.00 P62 1500 $ 6,000,000.00 P71 2500 $ 11,250,000.00 P21 1000 $ 4,000,000.00 P65 2500 $ 10,000,000.00 $ - P22 1500 $ 6,000,000.00 P66 2000 $ 8,000,000.00 $ - P23 250 $ 1,000,000.00 P67 1000 $ 4,000,000.00 $ - P24 250 $ 1,000,000.00 P68 500 $ 2,000,000.00 $ - P25 900 $ 3,600,000.00 P69 1000 $ 4,000,000.00 $ - P26 300 $ 1,200,000.00 P71 500 $ 2,000,000.00 $ - P27 250 $ 1,000,000.00 Total 41025 $ 164,100,000.00 Total 16175 $ 72,787,500.00

Promenade/Quay Wall: Low Density Area ($7,500/LF) Promenade/Quay Wall: Medium Density Area ($12,000/LF) Promenade/Quay Wall: High Density Area ($15,000/LF) Property/Structure Length (ft) Cost Property/Structure Length (ft) Cost Property/Structure Length (ft) Cost P4/ QW 800 $ 6,000,000.00 P26/ QW 3200 $ 38,400,000.00 P31/ QW 5500 $ 82,500,000.00 P14/ QW 275 $ 2,062,500.00 P30/ QW 1250 $ 15,000,000.00 P35/ QW 300 $ 4,500,000.00 P15/ QW 600 $ 4,500,000.00 P36/ QW 1000 $ 12,000,000.00 P37/ QW 2300 $ 34,500,000.00 $ - P40/ QW 1300 $ 15,600,000.00 P39/ QW 125 $ 1,875,000.00 $ - P40/ PRM 4100 $ 49,200,000.00 P51/ QW 1850 $ 27,750,000.00 $ - P41/ QW 2000 $ 24,000,000.00 P53/ QW 825 $ 12,375,000.00 $ - P48/ QW 1450 $ 17,400,000.00 P54/ PRM 750 $ 11,250,000.00 $ - P49/ QW 400 $ 4,800,000.00 P54/ QW 1000 $ 15,000,000.00 $ - P50/ QW 1150 $ 13,800,000.00 $ - $ - P52/ QW 775 $ 9,300,000.00 $ - $ - P54/ PRM 1350 $ 16,200,000.00 $ - $ - P54/ QW 400 $ 4,800,000.00 $ - $ - P55/ PRM 1200 $ 14,400,000.00 $ - $ - P56/ PRM 2600 $ 31,200,000.00 $ - $ - P59/ QW 600 $ 7,200,000.00 $ - Total 1675 $ 12,562,500.00 Total 22775 $ 273,300,000.00 Total 12650 $ 189,750,000.00

Pier/Wharf: Small Scale ($10,000/LF) Pier/Wharf: Medium Scale ($15,000/LF) Pier/Wharf: Large Scale ($30,000/LF) Property/Structure Length (ft) Cost Property/Structure Length (ft) Cost Property/Structure Length (ft) Cost P2/Wharf 250 $ 2,500,000.00 P10/Pier (3) 650 $ 9,750,000.00 P24 Pier 850 $ 25,500,000.00 P3/Wharf 625 $ 6,250,000.00 P11/Pier 250 $ 3,750,000.00 P26 Pier (5) 3025 $ 90,750,000.00 P8/Pier 350 $ 3,500,000.00 P12/Pier 1300 $ 19,500,000.00 P27 Pier (2) 850 $ 25,500,000.00 P9/Wharf 1200 $ 12,000,000.00 P16/Pier (2) 1225 $ 18,375,000.00 P31/Wharf 11700 $ 351,000,000.00 P15/Pier 500 $ 5,000,000.00 P17/Pier 150 $ 2,250,000.00 P36/Pier 675 $ 20,250,000.00 P17/Wharf 400 $ 4,000,000.00 P18/Pier 600 $ 9,000,000.00 P37/Pier (3) 1775 $ 53,250,000.00 P17/Pier 600 $ 6,000,000.00 P19/Pier (2) 625 $ 9,375,000.00 P38/Pier 1200 $ 36,000,000.00 P20/Pier 150 $ 1,500,000.00 P20/Pier 300 $ 4,500,000.00 P39/Pier 2400 $ 72,000,000.00 P25/Wharf 400 $ 4,000,000.00 P21/Pier 450 $ 6,750,000.00 P39/Wharf 1800 $ 54,000,000.00 P26/Pier 350 $ 3,500,000.00 P23/Pier 500 $ 7,500,000.00 P45/Wharf 400 $ 12,000,000.00 P27/Pier 250 $ 2,500,000.00 P26/Pier 225 $ 3,375,000.00 P45/Pier 1700 $ 51,000,000.00 P29/Pier 175 $ 1,750,000.00 P27/Wharf 400 $ 6,000,000.00 P65/Pier 500 $ 15,000,000.00 P32/Pier 200 $ 2,000,000.00 P30/Pier 200 $ 3,000,000.00 $ - P35/Pier (2) 450 $ 4,500,000.00 P32/Wharf 900 $ 13,500,000.00 $ - P44/Pier 125 $ 1,250,000.00 P33/Pier (2) 850 $ 12,750,000.00 $ - P61/Pier (2) 450 $ 4,500,000.00 P34/Pier (2) 1450 $ 21,750,000.00 $ - P63/Pier 100 $ 1,000,000.00 P48/Pier 450 $ 6,750,000.00 $ - P64/Pier 300 $ 3,000,000.00 P49/Pier 525 $ 7,875,000.00 $ - P69/Pier (2) 475 $ 4,750,000.00 P59/Pier (5) 1500 $ 22,500,000.00 $ - P70/Pier (2) 1000 $ 10,000,000.00 P64/Pier 800 $ 12,000,000.00 $ - P71/Pier (2) 400 $ 4,000,000.00 P67/Wharf 100 $ 1,500,000.00 $ - $ - P69/Pier 850 $ 12,750,000.00 $ - $ - P70/Pier (2) 1625 $ 24,375,000.00 $ - $ - P71/Pier (2) 525 $ 7,875,000.00 $ - Total 8750 $ 87,500,000.00 Total 16450 $ 246,750,000.00 Total 26875 $ 806,250,000.00

Shoreline Barrier Category Cost Factor ($/LF) Length (ft) Cost (FY19 USD) Seawall (Low Density Area) Cost $3,000 81219 $ 243,657,000.00 Seawall (Med Density Area) Cost $4,000 41025 $ 164,100,000.00 Seawall (High Density Area) Cost $4,500 16175 $ 72,787,500.00 Promenade/Quay Wall (Low) Cost $7,500 1675 $ 12,562,500.00 Promenade/Quay Wall (Med) Cost $12,000 22775 $ 273,300,000.00 Promenade/Quay Wall (High) Cost $15,000 12650 $ 189,750,000.00 Pier/Wharf (Small) Cost $10,000 8750 $ 87,500,000.00 Pier/Wharf (Med) Cost $15,000 16450 $ 246,750,000.00 Pier/Wharf (Large) Cost $30,000 26875 $ 806,250,000.00 Tidal Combo Wall Cost $10,000 7160 $ 71,600,000.00 Tidal Sluice Gate Cost $50,000 475 $ 23,750,000.00 Tidal Miter Gate Cost $75,000 2300 $ 172,500,000.00 Tidal Sector Gate Cost $645,000 270 $ 174,150,000.00 Hybrid Shoreline Barrier System Totals 237799 $ 2,538,657,000.00 THIS PAGE INTENTIONALLY LEFT BLANK

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