FY 2019-2020 Virginia Beach Budget Response to Council ...€¦ · Figure 12: MIKE 21 SW model significant wave height at Norfolk wave gage and water levels at Sewells Point, Hurricane

FY 2019-2020 Virginia Beach Budget Response to Council Questions

Question Number: FY 20 21 Question: Please provide a copy of the Beach engineering reports for Chesapeake Beach. Date Requested: February 26, 2019 Requested By: Councilmember Moss Department: Public Works-Coastal Response: See attached documentation.

Ocean Park Beach and Cape Henry Beach Nourishment Template Conceptual

Engineering Study

Presented to:

City of Virginia Beach, Department of Public Works Draft Final Report – March 2019

Prepared by:

Ocean Park Beach and Cape Henry Beach Nourishment Template Study City of Virginia Beach

9859-06 Moffatt & Nichol ii

Table of Contents Executive Summary ............................................................................................................................... 1

1. Introduction ..................................................................................................................................... 4

1.1. Study Purpose and Scope ........................................................................................................ 4

2. Engineering Study Approach ........................................................................................................ 11

2.1. Historical Data Compilation and Analysis ............................................................................ 11

2.2. Wave Transformation Modeling ........................................................................................... 11

2.3. Beach Nourishment Template Conceptual Design ............................................................... 12

3. Historical Data Compilation and Analysis.................................................................................... 15

3.1. Tidal Elevations ..................................................................................................................... 15

3.2. Historical Beach Profiles ....................................................................................................... 15

3.3. Historical Shorelines ............................................................................................................. 16

3.4. Existing Beach Sediment Characteristics .............................................................................. 16

3.5. Sediment Source Characteristics ........................................................................................... 19

4. Wave Transformation Modeling ................................................................................................... 20

4.1. Spectral Wave Model Description ........................................................................................ 20

4.2. USACE WIS Waves for Continuous Simulation: 2009 – 2016 ............................................ 26

4.3. Typical Annual Nearshore Waves: 2009 – 2016................................................................... 27

4.4. Nearshore Storm Waves ........................................................................................................ 29

5. Beach Nourishment Template Conceptual Design ....................................................................... 33

5.1. Introduction ........................................................................................................................... 33

5.2. Beach Nourishment Alternatives Development .................................................................... 33

5.3. Beach Profile Storm Response: Present Sea Levels .............................................................. 40

5.3.1. Ocean Park Beach .......................................................................................................... 40

5.3.2. Cape Henry Beach ......................................................................................................... 44


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5.4. Beach Profile Storm Response: With Sea Level Rise ........................................................... 47

6. Longshore Sediment Transport and Shoreline Evolution ............................................................. 50

6.1. LITLINE Model Setup .......................................................................................................... 50

6.2. LITLINE Model Calibration/Validation for Ocean Park Beach ........................................... 51

6.3. LITLINE Model Calibration/Validation for Cape Henry Beach .......................................... 53

6.4. Beach Nourishment Template Alternatives’ Shoreline Evolution ........................................ 55

7. Recommended Conceptual Design Template ............................................................................... 61

7.1. Minimum Beach Berm Width at Each Station ...................................................................... 61

7.2. Advance Nourishment and Estimated Renourishment Interval ............................................ 61

7.3. Recommended Conceptual Design Profiles .......................................................................... 64

8. Conclusions and Recommendations ............................................................................................. 69

8.1. Conclusions ........................................................................................................................... 70

8.2. Recommendations ................................................................................................................. 70

9. References ..................................................................................................................................... 72

Appendix A: Beach Profile Location and Historical Beach Profiles (Ocean Park Beach) ................... 1

Appendix B: Beach Profile Location and Historical Beach Profiles (Cape Henry Beach) .................. 2

Appendix C: Wave and Wind Roses at WIS Station 63197 ................................................................. 3

Appendix D: SBEACH Storm Erosion Results with Present Sea Level (Ocean Park Beach) ............. 4

Appendix E: SBEACH Storm Erosion Results with Present Sea Level (Cape Henry Beach) ............. 5

Appendix F: SBEACH Storm Erosion Results with 1.5 Feet of SLR (Ocean Park Beach) ................. 6

Appendix G: SBEACH Storm Erosion Results with 1.5 Feet of SLR (Cape Henry Beach) ................ 7

Appendix H: LITLINE Shoreline Evolution Results (Ocean Park Beach) ........................................... 8

Appendix I: LITLINE Shoreline Evolution Results (Cape Henry Beach) ............................................ 9

Appendix J: Recommended Conceptual Design Profiles Including Advance Nourishment (Ocean Park Beach) .................................................................................................................... 10

Appendix K: Recommended Conceptual Design Profiles Including Advance Nourishment (Cape Henry Beach) ................................................................................................................. 11


9859-06 Moffatt & Nichol iv

List of Figures

Figure 1: Location of Ocean Park Beach and Cape Henry Beach ......................................................... 4

Figure 2: Ocean Park Beach Survey Baseline with Stationing .............................................................. 7

Figure 3: Cape Henry Beach Survey Baseline with Stationing.............................................................. 8

Figure 4: Ocean Park Beach Parcel-Level Assessed Improvement Values ........................................... 9

Figure 5: Cape Henry Beach Parcel-Level Assessed Improvement Values ........................................ 10

Figure 6: Ocean Park Beach Sand Sample Locations .......................................................................... 17

Figure 7: Cape Henry Beach Sand Sample Locations ......................................................................... 17

Figure 8: Wave, Wind, and Water Level Data Locations .................................................................... 21

Figure 9: MIKE 21 SW Wave Model Domain with Variable-resolution Computational Mesh .......... 22

Figure 10: Variable-resolution Computational Mesh at Project Sites .................................................. 23

Figure 11: MIKE 21 SW wave model domain with bathymetry in meters NAVD88 ......................... 24

Figure 12: MIKE 21 SW model significant wave height at Norfolk wave gage and water levels at Sewells Point, Hurricane Irene ............................................................................................................. 25

Figure 13: MIKE 21 SW model significant wave height at Norfolk wave gage and water levels at Sewells Point, 2009 nor’easter ............................................................................................................. 25

Figure 14: Historical Wave and Wind Data Location of WIS Station 63197 ...................................... 26

Figure 15: Nearshore Wave Data Locations ........................................................................................ 27

Figure 16: Wave Rose at Location OC12 ............................................................................................ 28

Figure 17: Nearshore Wave Height Distributions for November 2009 nor’easter .............................. 29

Figure 18: Nearshore Wave and Water Level Conditions for the November 2009 Nor’easter at OC8 .............................................................................................................................................................. 29

Figure 19: Nearshore Wave and Water Level Conditions for the November 2009 Nor’easter at OC12 .............................................................................................................................................................. 30

Figure 20: Nearshore Wave and Water Level Conditions for the Hurricane Isabel (2003) at OC8 .... 30


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Figure 21: Nearshore Wave and Water Level Conditions for the Hurricane Isabel (2003) at OC12 .. 31

Figure 22: Nearshore Wave and Water Level Conditions for the Hurricane Isabel (2003) with Storm Surge Water Levels Scaled to Peak at 1% Annual Chance Stillwater of +7.0 ft NAVD88 at OC8 .... 31

Figure 23: Nearshore Wave and Water Level Conditions for the Hurricane Isabel (2003) with Storm Surge Water Levels Scaled to Peak at 1% Annual Chance Stillwater of +7.0 ft NAVD88 at OC12 .. 32

Figure 24. Ocean Park Beach Fill Design Templates at Station 10+00 ............................................... 34





Figure 29. Cape Henry Beach Fill Design Templates at Station 115+00 ............................................ 37






Figure 35. Existing Condition SBEACH Simulation Results for Ocean Park Beach Station 10+00 .. 41



Figure 38. Existing Condition SBEACH Simulation Results for Cape Henry Beach Station 135+00 44

Figure 39. Existing Condition SBEACH Simulation Results for Cape Henry Beach Station 155+00 45

Figure 40: Longshore Sediment Transport Rate at Ocean Park Beach (December 2014 to December 2015) ..................................................................................................................................................... 52

Figure 41: Comparison between Measured and Calculated Shoreline Changes at Ocean Park Beach (December 2014 to December 2015) ................................................................................................... 52


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Figure 42: Comparison between Measured and Calculated Shoreline Changes at Ocean Park Beach (May 2012 to May 2013) ..................................................................................................................... 53

Figure 43: Longshore Sediment Transport Rate at Cape Henry Beach (June 2014 to October 2015) .............................................................................................................................................................. 54

Figure 44: Comparison between Measured and Calculated Shoreline Changes at Cape Henry Beach (June 2014 to October 2015) ................................................................................................................ 54

Figure 45: Comparison between Measured and Calculated Shoreline Changes at Cape Henry Beach (March 2012 to July 2013) ................................................................................................................... 55

Figure 46: Shoreline Performance for Alternatives 4 for Ocean Park Beach ...................................... 57

Figure 47: LITLINE Shoreline Evolution in Two Years Post-Nourishment for Alternatives 1 through 4 for Ocean Park Beach ........................................................................................................................ 58

Figure 48: Shoreline Performance for Alternatives 4 for Cape Henry Beach ..................................... 59

Figure 49: LITLINE Shoreline Evolution in Four Years Post-Nourishment for Alternatives 1 through 4 for Cape Henry Beach ....................................................................................................................... 60

Figure 50: LITLINE Shoreline Evolution for Recommended Conceptual Design Including Advance Nourishment (Ocean Park Beach) ........................................................................................................ 62

Figure 51: LITLINE Shoreline Evolution for Recommended Conceptual Design Including Advance Nourishment (Cape Henry Beach) ....................................................................................................... 63


9859-06 Moffatt & Nichol vii

List of Tables

Table 1: Assessed Values of Properties Located Seaward of Shore Drive in the Project Area ............. 5

Table 2: Historical Beach Volumetric Changes ................................................................................... 15

Table 3: Historical Shoreline Changes ................................................................................................. 16

Table 4: Existing beach sediment characteristics ................................................................................. 18

Table 5: Storm Wave Height and Water Level Parameters at OC8 in SBEACH Simulations ............ 32

Table 6: Parameters for the SBEACH Model ...................................................................................... 40

Table 7: SBEACH Storm Erosion Results for Existing Conditions and Conceptual Alternative Templates at Present Sea Level for Ocean Park Beach ....................................................................... 43

Table 8: SBEACH Storm Erosion Results for Existing Conditions and Conceptual Alternative Templates at Present Sea Level for Cape Henry Beach ....................................................................... 46

Table 9: SBEACH Storm Erosion Results for Existing Conditions and Conceptual Alternative Templates with 1.5 feet SLR for Ocean Park Beach ............................................................................ 48

Table 10: SBEACH Storm Erosion Results for Existing Conditions and Conceptual Alternative Templates with 1.5 feet SLR for Cape Henry Beach ........................................................................... 49

Table 11: LITLINE Model Setup Parameters ...................................................................................... 51

Table 12: Minimum Distance between MTL Shoreline and Existing Structures at Present Sea Levels .............................................................................................................................................................. 61

Table 13: Distance between the MTL shoreline and the Existing Structures for Alternative 4........... 64

Table 14: Description of Recommended Conceptual Beach Nourishment Design Profiles along Ocean Park Beach ............................................................................................................................................ 65

Table 15: Description of Recommended Conceptual Beach Nourishment Design Profiles along Cape Henry Beach ......................................................................................................................................... 66

Table 16: Fill Volumes for Constructing Recommended Conceptual Beach Nourishment Design for Ocean Park Beach ................................................................................................................................ 67

Table 17: Fill Volumes for Constructing Recommended Conceptual Beach Nourishment Design for Cape Henry Beach ................................................................................................................................ 68


9859-06 Moffatt & Nichol | Executive Summary 1

Executive Summary

This report documents a coastal engineering study and a recommended conceptual engineering design for proposed beach nourishment projects (1) along Ocean Park Beach, approximately between Windy Road and Lynnhaven Inlet, and (2) along Cape Henry Beach, approximately between Lynnhaven Inlet and Hendall Street in Virginia Beach. Historically, the City has utilized sediments dredged from Lynnhaven Inlet as nourishment for both beaches. The purpose of this study is three-fold:

1. Recommend a conceptual plan and profile through the efficient use of available sediment sources for an ongoing nourishment program for both beaches;

2. Provide an increased level of resilience in coastal storms; and 3. Enhance the recreational beach.

The study evaluated historical beach volume change and shoreline position change trends, longshore transport rates and gradients, and published data on potential sediment borrow area properties. A numerical shoreline evolution and storm-induced beach profile erosion model were used to evaluate alternative design beach profiles. The study culminates in recommendation of a design beach and dune profile to provide a level of protection to existing structures from a coastal storm similar to the November 2009 Nor’easter. That storm had peak water levels equivalent to approximately a 40-year return period (2.5% annual chance), with depth-limited waves impacting the project area. The Recommended Conceptual Design for the proposed beach nourishment includes advance nourishment to allow for the expected typical annual shoreline retreat over an estimated four-year interval between planned renourishment events.

The Recommended Conceptual Design includes a mix of the studied beach profile alternatives’ cross-sections, based on survey stations. The recommended designs at each section in Ocean Park Beach are described in Table ES-1 and Table ES-2. The recommended designs at each section in Cape Henry Beach are described in Table ES-3 and Table ES-4. Approximately 294,000 cubic yards are required to construct the Recommended Conceptual Design, including advance nourishment for Ocean Park Beach; a volume of approximately 245,000 cubic yards is required to construct the recommended template at Cape Henry Beach. Recommended Conceptual Design profile plots at each station are provided in Appendix J and Appendix K. It is expected that the primary source of nourishment sand would be from hydraulic dredging of the Lynnhaven Inlet system. Sand may alternatively be available from hopper dredging in the Atlantic Ocean Channel or Thimble Shoals Channel as part of navigation channel maintenance and expansion. Sand hauled in by trucks from upland quarries may also be utilized, in situations where insufficient quantities are available at a particular time through dredging.

Model results show that the shoreline position in the erosional hot spot area between stations 10+00 and 20+00 at Ocean Park Beach, and between stations 130+00 and 140+00 at Cape Henry Beach, are likely to retreat to a minimum position for desired storm protection within four years after initial construction. It is recommended that the City plan and budget for a renourishment at these hot spot areas in Ocean Park Beach and Cape Henry Beach approximately every four years. The occurrence of a severe or prolonged coastal storm event, or greater than typical frequency of storms (post-construction), may accelerate the need for renourishment in the hot spot areas.



Table ES-1: Description of Recommended Conceptual Nourishment Design: Ocean Park Beach

No. Minimum Beach Berm Distance from +7 NAVD

Advance Nourishment Beyond Minimum Berm Width

5+00 - - 10+00 70 feet 62 feet 15+00 90 feet 110 feet 20+00 80 feet 79 feet 25+00 60 feet 40 feet 30+00 80 feet 10 feet 35+00 70 feet 10 feet 40+00 50 feet 10 feet 45+00 40 feet 20 feet 50+00 50 feet 20 feet 55+00 50 feet 20 feet 60+00 70 feet 20 feet 65+00 70 feet 20 feet 70+00 70 feet 20 feet 75+00 - -

Table ES-2: Fill Volumes for Constructing Recommended Conceptual Design for Ocean Park Beach

Station No. Section Fill Density (cy/ft) 5+00 0.0

10+00 62.7 15+00 114.2 20+00 77.9 25+00 41.6 30+00 33.6 35+00 30.0 40+00 29.9 45+00 38.8 50+00 31.1 55+00 26.7 60+00 25.2 65+00 39.3 70+00 37.1 75+00 0.0



Table ES-3: Description of Recommended Conceptual Nourishment Design: Cape Henry Beach

Station No. Minimum Beach Berm Distance from +7 NAVD

Advance Nourishment Beyond Minimum Berm Width

105+00 - - 110+00 15 feet 20 feet 115+00 35 feet 20 feet 120+00 30 feet 20 feet 125+00 35 feet 27 feet 130+00 80 feet 170 feet 135+00 70 feet 190 feet 140+00 50 feet 122 feet 145+00 44 feet 59 feet 150+00 55 feet 20 feet 155+00 30 feet 20 feet 160+00 35 feet 20 feet 165+00 20 feet 20 feet 170+00 40 feet 13 feet 175+00 25 feet 11 feet 180+00 35 feet 5 feet 185+00 35 feet 0 feet 190+00 20 feet 0 feet 195+00 25 feet 0 feet 200+00 - -

Table ES-4: Fill Volumes for Constructing Recommended Conceptual Design for Cape Henry Beach

Station No. Section Fill Density (cy/ft) Station No. Section Fill Density (cy/ft) 105+00 0.0 155+00 28.4 110+00 19.9 160+00 15.5 115+00 20.4 165+00 16.8 120+00 26.7 170+00 1.8 125+00 15.5 175+00 1.1 130+00 116.7 180+00 1.8 135+00 111.4 185+00 0.8 140+00 54.6 190+00 0.9 145+00 25.3 195+00 2.9 150+00 18.7 200+00 0.0


9859-06 Moffatt & Nichol | Introduction 4

1. Introduction

1.1. Study Purpose and Scope

Moffatt & Nichol (M&N) was retained by the City of Virginia Beach (City) to provide a study and conceptual engineering designs of alternative beach profile templates for enhancing and maintaining coastal storm resilience through sand nourishment at Ocean Park Beach and Cape Henry Beach. Ocean Park Beach and Cape Henry Beach are located along the southern coast of the Chesapeake Bay adjacent to the southern end of the Chesapeake Bay Bridge-Tunnel and approximately between Windy Road and Kendall Street (just west of the First Landing State Park). Ocean Park Beach is part of a 4.9 mile shoreline segment between Little Creek Inlet and Lynnhaven Inlet. Cape Henry Beach sits between the eastern shoreline of Lynnhaven Inlet (Figure 1) and First Landing State Park.

Figure 1: Location of Ocean Park Beach and Cape Henry Beach



In preparation for a potential sand nourishment of Ocean Park Beach and Cape Henry Beach, the City and M&N staff discussed engineering studies and design tasks required to support Ocean Park Beach nourishment and Cape Henry Beach nourishment. The studies and design tasks include: evaluation of historical beach volume change and shoreline position change trends, longshore transport rates and gradients, and published data on sediment borrow area properties, with recommendations for beach nourishment profile templates and renourishment intervals. The objective of the project is to provide a beach profile template for nourishment construction that effectively balances shoreline advancement (with associated storm resilience and recreational beach width) with realistic total nourishment volumes.

The City has conducted annual beach and nearshore monitoring surveys along the project beaches for several years. Figure 2 and Figure 3 show survey baselines in Ocean Park Beach and Cape Henry Beach. Stations along this baseline will be referenced throughout this report to describe historical and existing conditions of the beach and to discuss recommendations regarding beach fill templates that may vary between groups of Stations.

Both Ocean Park Beach and Cape Henry Beach are urban beach communities with a blend of older single-family residences and bungalows with multi-unit condominiums, including the Westminster-Canterbury senior community. Figure 4 and Figure 5 illustrate the City’s assessed property improvement values aggregated by parcel, i.e. the value shown includes all of the values of the individual units on each parcel. The improvements value indicates the economic value of built assets that would be likely to suffer damage in a coastal storm surge and wave event. Table 1 summarizes the property assessment data provided to M&N by the City for the purposes of this study. This data indicates that very significant economic value is associated with the recreational and residential activity provided by these two reaches of beachfront, such that providing and maintaining protection from coastal storms is economically justified.

Table 1: Assessed Values of Properties Located Seaward of Shore Drive in the Project Area

Location Parcel Value

Improvements Value

Total Assessed Value

Ocean Park Beach, Seaward of Shore Drive $233,950,500 $218,045,600 $451,996,100

Ocean Park Beach, First Row of Parcels to the Beach $77,652,800 $85,877,100 $163,529,900

Ocean Park Beach, Seaward of Shore Drive $394,995,100 $574,648,700 $969,643,800

Ocean Park Beach, First Row of Parcels to the Beach $253,201,400 $434,981,900 $688,183,300

The purpose of this report is to document the evaluation of alternative beach profile templates for sand nourishment at Ocean Park Beach and Cape Henry Beach to inform the City’s nourishment project permitting and design process. M&N’s scope of work includes compilation and analysis of existing available data relative to the project vicinity; review of prior engineering study reports in the project vicinity; and limited new numerical modeling of coastal processes.



The engineering study documented in this report can also be a first step toward a documented design basis, maintenance plan, and monitoring plan to facilitate qualifying the Ocean Park Beach and Cape Henry Beach project area for FEMA post-disaster Public Assistance as an “improved beach,” should the project proceed to construction. Qualifying Ocean Park Beach and Cape Henry Beach as “improved beach” would require additional tasks outside of this study’s scope, including coordination with FEMA. At a minimum, regular beach and nearshore monitoring surveys, and immediate post-storm surveys would be required for qualifying and submitting claims for FEMA Public Assistance funding following storm disaster declarations.



Figure 2: Ocean Park Beach Survey Baseline with Stationing



Figure 3: Cape Henry Beach Survey Baseline with Stationing



Figure 4: Ocean Park Beach Parcel-Level Assessed Improvement Values



Figure 5: Cape Henry Beach Parcel-Level Assessed Improvement Values


9859-06 Moffatt & Nichol | Engineering Study Approach 11

2. Engineering Study Approach

2.1. Historical Data Compilation and Analysis

The development and analysis of potential beach nourishment templates for Ocean Park Beach and Cape Henry Beach started with a comprehensive analysis of available data. Data collected for the City and other publicly-available data sets relative to beach morphology and shoreline change at Ocean Park Beach and Cape Henry Beach were compiled and reviewed. Available data sets include historical beach profile and shoreline position survey data; aerial photography; publicly available wave, current, tide, and wind data; sediment data; and prior coastal engineering studies by others. These data sets were used to evaluate historical shoreline and beach volume change trends. Historical data sources utilized include:

• Historical beach profile data – Reports, maps and ASCII text survey station-elevation data files from City completed in May 2012, May 2013, December 2014, December 2015 and December 2016 for Ocean Park Beach, and March 2012, July 2013, June 2014, October 2015 and October 2016 for Cape Henry Beach.

• Hindcast wave and wind data from USACE WIS Atlantic Hindcast Station 63197.

• Measured wave data from NOAA data buoys #44014 and #44099 in the Atlantic Ocean immediately outside the Chesapeake Bay entrance.

• Measured wave data from City of Norfolk’s Nortek AWAC Acoustic Doppler instrument were used to calibrate the wave transformation model, during a prior study. This instrument is located approximately 5.9 miles northwest of the Chesapeake Bay Bridge-Tunnel in a water depth of approximately 24 feet.

• Observed water surface elevation data from NOAA tide gauging station 8638863 at the Chesapeake Bay Bridge-Tunnel.

• Sediment characteristics data – Report by GET Solutions, Inc. (January 2018) Particle Size Distribution Reports (Ocean Park Beach and Cape Henry Beach).

2.2. Wave Transformation Modeling

Evaluation of the conceptual beach nourishment design alternatives (and estimation of required renourishment intervals) depends significantly on expected wave conditions and associated longshore sediment transport rates. Measured wave heights, periods and directions were transformed to the nearshore along Ocean Park Beach and Cape Henry Beach from available data positions immediately outside Chesapeake Bay in the Atlantic Ocean. Measured wave data are available for recent years at stations from NOAA’s National Data Buoy Center (NDBC) and the U.S. Army Corps of Engineers’ (USACE) Wave Information Studies (WIS) archive. These were utilized as input to a spectral wave model. This model has been developed by M&N for several prior projects, and it has been previously calibrated by M&N using measured wave data within the lower Chesapeake Bay. For the Ocean Park Beach and Cape Henry Beach evaluations, the model was modified to include detailed nearshore



bathymetry along the shoreline between Little Creek Inlet and First Landing State Park. The wave transformation model simulations produced wave conditions to be used as input to simulations of beach profile change during storms and in calculation of net and gross longshore sediment transport rates and shoreline change in representative annual conditions.

2.3. Beach Nourishment Template Conceptual Design

For the purposes of this study, it was assumed that the primary source of sediment for beach nourishment would be sand obtained by hydraulic dredging of Lynnhaven Inlet or by hopper dredging of navigation channels such as the Atlantic Ocean Channel and Thimble Shoals Channel. The available field data and the results of prior sediment studies were used to evaluate the need for nourishment overfill. A nourishment overfill (or overfill ratio) analysis estimates the volume of fill required to achieve a desired beach width given native and source sediment properties.

The maintenance of beach width along Ocean Park Beach and Cape Henry Beach, for recreation and storm damage mitigation, is expected to be accomplished through beach nourishment projects. The objective of the conceptual design process is to determine beach and dune profile volumes and geometries (design elevations and widths) that are feasible and meet the City’s criteria within the constraints of the available sediment borrow area and potentially available construction funding. Beach and dune design template and nourishment interval alternatives were developed and evaluated with respect to recreational and storm damage mitigation benefit provided.

Beach Nourishment Alternative Development

Nourishment of Ocean Park Beach and Cape Henry Beach is expected to be constructed primarily by hydraulic placement from dredging, in which the dredged sand is pumped onto the beach then formed into the construction template by earth moving equipment. In general, the unit cost per cubic yard of sand placed on the beach decreases as the total nourishment event volume increases. However, the initial erosion rates of beach nourishment projects generally increase with distance that the shoreline is advanced seaward. The most economical beach nourishment and maintenance plans achieve a balance between initial placement volume, initial shoreline advancement, and expected future renourishment intervals and volumes.

Utilizing the evaluated results of historical beach and shoreline change trends surrounding Ocean Park Beach and Cape Henry Beach, M&N developed and evaluated four (4) alternative beach nourishment design templates; alternatives consist of varying combinations of beach width, beach berm elevation, dune crest elevation, and beach renourishment intervals. The required initial nourishment volumes to construct each design template were calculated. The advanced beach nourishment volumes and renourishment intervals to maintain the target design profile through multiple years of long-term annual erosion were proposed.

Potential increases to beach profile crest elevations and volumes needed to keep pace with future mean sea level rise (SLR) were considered in this evaluation. A SLR estimate of 1.5 feet was evaluated, which is the projected rate over the next 30 to 50 years, as recommended by the Virginia Institute of Marine Science (VIMS, 2013).



Beach Profiles Storm Response and Benefits

The additional storm wave damage mitigation offered by the beach profile design alternatives was evaluated using the SBEACH model of beach profile storm response. M&N used SBEACH simulations of representative design storm wave and surge conditions to evaluate the erosion of beach width and dune volume, and the landward limits of wave damage during four (4) simulated storm events that include a November 2009 nor’easter; Hurricane Isabel in September 2003; and a modified version of Hurricane Isabel in September 2003 with 50-year and 100-year return period storm surges. The purpose of this component of the analysis is to determine the ability of different design alternatives to resist dune overtopping/breaching and excessive beach berm retreat during a particular design storm event. The magnitude of the design storm event for this study ranges from a typical major nor’easter to a typical Category 2 hurricane1. Minor to moderate nor’easters were not simulated. In this study, the November 2009 nor’easter represents a typical major nor’easter with longer duration, and Hurricane Isabel (September 2003) represents a hurricane with higher intensity waves but shorter duration than a major nor’easter. The effects on the beach profile of hurricane waves occurring at a very high water level were simulated by using the storm surge “shape” from Hurricane Isabel with the peak water level scaled to reflect the 2015 effective FEMA Flood Insurance Study (FIS) 1% annual chance water level.

Longshore Sediment Transport and Shoreline Evolution

The analyzed historical data provide valuable information regarding historical rates of change in the study area, sediment transport and shoreline erosion rates for the nourished beach. A limited program of sediment transport modeling, supported by results of the wave transformation model, was proposed for obtaining the required calculations of longshore transport and shoreline change rates pre- and post-nourishment.

M&N evaluated annual longshore sediment transport gradients and shoreline recession rates through application of the DHI LITLINE shoreline evolution model. Two separate LITLINE models were utilized: The Ocean Park Beach model covers from the western shoreline of Lynnhaven Inlet (on the east) to JEB Little Creek on the west, encompassing Chesapeake Beach to capture the shoreline processes. The Cape Henry Beach model covers from the Lynnhaven Inlet eastern shoreline to First Landing State Park. The required model inputs include:

• Representative sediment characteristics; • Representative nearshore wave climate for the site; • Historical shoreline positions relative to an established landward baseline, for dates

coinciding with the available nearshore wave time series; and • Positions and dimensions of existing shoreline structures (breakwaters, groins, and

seawalls) relative to the established baseline.

1 Hurricane Isabel (2003) was a Category 2 hurricane with sustained wind speed when it made landfall near Ocracoke Inlet, NC, approx. 145 miles south of Cape Henry. Isabel was a Category 1 hurricane when it crossed into Virginia near Roanoke Rapids, NC.



Calibration and validation of the LITLINE shoreline model were made using the available historical shoreline surveys. The LITLINE shoreline model then was used to simulate shoreline positions for representative “typical annual” years including both storm and non-storm wave conditions. Results from the various model sequences were analyzed to determine a range of annualized shoreline recession rates and beach volume losses under existing conditions.


9859-06 Moffatt & Nichol | Historical Data Compilation and Analysis 15

3. Historical Data Compilation and Analysis

Available historical data sets including historical beach profiles, shorelines, wave and wind conditions, tide elevations and sediment characteristics were compiled and analyzed. These data sets were utilized for wave transformation modeling, longshore sediment transport and shoreline evolution, and beach profile storm response and benefit analysis.

3.1. Tidal Elevations

Historical measured tide elevation data used in this study were collected from the NOAA tide gauge 8638863 at Chesapeake Bay Bridge Tunnel, VA, as illustrated in Figure 8. This data was used to provide time-varying water levels for the wave transformation and beach profile change modeling components of this study.

3.2. Historical Beach Profiles

A beach monitoring program was initiated by the City in to document changes along the Ocean Park Beach shoreline and the Cape Henry Beach shoreline. Beach Monitoring surveys have been conducted by Waterway Surveys & Engineering (WS&E), and the survey data and reports from this program were supplied to M&N by the City for use in this study. Monitoring ranges were established approximately every 500 feet beginning near the Lynnhaven Inlet (Station 0+00) and extending west to the near Windy Road (Station 75+00) for Ocean Park Beach; and beginning near the Lynnhaven Inlet (Station 100+00) and extending east to the near Calvert Street (Station 200+00) for Cape Henry Beach. The surveys included both the sub-aerial beach and offshore area to distances exceeding approximately 3,000 feet from the shoreline. To date, Ocean Park Beach has been surveyed five times as part of this monitoring program (May 2012, May 2013, December 2014, December 2015 and December 2016); and Cape Henry Beach has been surveyed five times as part of this monitoring program (March 2012, June 2013, June 2014, October 2015 and October 2016). Historical beach profile locations and charts at all transects are included in Appendix A and Appendix B of this report.

The beach profile monitoring data show that Ocean Park Beach and Cape Henry Beach are moderately eroding coastal areas that are susceptible to storm impacts. Volumetric changes calculated by M&N from the survey data above the elevations indicated are presented in Table 2 for Ocean Park Beach and Cape Henry Beach, respectively.

Table 2: Historical Beach Volumetric Changes

Period Ocean Park Beach

(cy/yr/ft) Cape Henry Beach

(cy/yr/ft) Above MLW Above -11’ NAVD Above MLW Above -5’ NAVD

May 2012 to May 2013 -2.0 -9.1 - - Dec. 2014 to Dec. 2015 -2.7 -20.2 - - Mar. 2012 to Jun. 2013 - - -2.1 -4.1 Jun. 2014 to Oct. 2015 - - -1.5* +0.3*

*Including small beach nourishment between transects 100+00 and 105+00



3.3. Historical Shorelines

For Ocean Park Beach, the positions of the Virginia Beach shoreline from May 2012, May 2013, December 2014 and December 2015 were used for the shoreline position analysis. For Cape Henry Beach, the positions of the Virginia Beach shoreline from March 2012, July 2013, June 2014 and October 2015 were used for the shoreline position analysis. The analyzed shoreline changes at MSL are presented in Table 3 for Ocean Park Beach and Cape Henry Beach, respectively.

Sand from maintenance dredging of Lynnhaven Inlet is regularly placed on the Ocean Park Beach shoreline west of the inlet. Construction of the Lesner Bridge across Lynnhaven Inlet in the 1950s fixed the location of the inlet. A USACE project for navigation requirements of the inlet began in the 1960s, when the first dredging project in 1965 removed 505,000 cubic yards from Lynnhaven Inlet. Since 1965 approximately 200,000 cy of sand has been dredged every three to four years. The sand dredged from Lynnhaven Inlet has primarily been placed as beach nourishment for Ocean Park Beach to the west of the inlet. The most recent beach nourishment project at the Ocean Park Beach was conducted in December 2013. A total of approximately of 1,134,000 cy of sand has been placed on the beaches west of Lynnhaven Inlet, with the vast majority of the sand coming from dredging of Lynnhaven Inlet (Basco, 2003).

Table 3: Historical Shoreline Changes

Period Ocean Park Beach

(ft/yr) Cape Henry Beach

(ft/yr)

May 2012 to May 2013 +3.2 - Dec. 2014 to Dec. 2015 -16.7 - Mar. 2012 to Jun. 2013 - -10.5 Jun. 2014 to Oct. 2015 - -14.3*

*Including small beach nourishment between transects 100+00 and 105+00

3.4. Existing Beach Sediment Characteristics

M&N obtained sediment samples in May 2017 along the existing beach at locations shown in Figure 6 and Figure 7. The samples were provided to GET Solutions (GET) for standard gradation testing. The median grain sizes for these samples are provided in Table 4. The samples indicate that the sediments of both beaches are typical medium sands, such as can be obtained by dredging the nearby inlet and other navigational channels in the area. The samples also indicate that the sand on Cape Henry Beach is generally coarser than the sand on Ocean Park Beach; this may be due to the fact that Cape Henry Beach has been nourished by direct placement of dredged sand from inlet, while nourishment of Ocean Park Beach has involved the nearshore submerged placement of dredged materials with wave action redistributing the sand.



Figure 6: Ocean Park Beach Sand Sample Locations

Figure 7: Cape Henry Beach Sand Sample Locations



Table 4: Existing beach sediment characteristics

Location Median Grain Size (D50), mm

Sorting (D85/D15)

Beach and Dune (M&N, May 2017) Ocean Park Beach

OP-1A 0.39 3.2 OP-1B 0.33 3.6 OP-2A 0.29 1.9 OP-2B 0.29 1.9 OP-3A 0.3 2.0 OP-3B 0.29 2.1 OP-4A 0.35 3.4 OP-4B 0.29 2.1 OP-5A 0.36 2.9 OP-5B 0.28 1.9

Average 0.317 2.5 Cape Henry Beach

CAP-1A 0.33 3.9 CAP-1B 0.4 3.7 CAP-2A 0.51 4.1 CAP-2B 0.68 4.5 CAP-3A 0.52 4.0 CAP-3B 0.34 3.3 CAP-4A 0.64 4.7 CAP-4B 0.43 3.6 CAP-5A 0.51 5.3 CAP-5B 0.73 3.6 Average 0.509 4.1



3.5. Potential Sediment Sources

Potential sediment sources for nourishment of Ocean Park Beach and Cape Henry Beach include sediment from periodic maintenance dredging of Lynnhaven Inlet, hydraulic dredging of the Chesapeake Beach Shoal (as utilized for the 2018 nourishment of Chesapeake Beach), hopper dredging of Chesapeake Bay and Atlantic Ocean navigation channels, and truck haul from various local and regional sources. Historical sediment data from all of these sources supports their compatibility as sources for nourishment of Ocean Park Beach and Cape Henry Beach. The specific sediment source utilized for each nourishment event at each of the beach areas will be best determined during the specific permitting and construction documents preparation phases for each event. The selection of a sediment source for each event will depend on factors such as cost, permit status, and interaction with other planned work. For example, nourishment of either Ocean Park Beach or Cape Henry Beach could be planned to coincide with Federal dredging of Lynnhaven Inlet or the Thimble Shoals Auxiliary Channel, so that the dredged materials could be used beneficially and cost-effectively.


9859-06 Moffatt & Nichol | Wave Transformation Modeling 20

4. Wave Transformation Modeling

4.1. Spectral Wave Model Description

The wave propagation study was conducted utilizing a third-generation, two-dimensional spectral wave model. The MIKE 21 Spectral Waves (SW) software was used to calculate wave conditions approaching Ocean Park Beach and Cape Henry Beach, using winds and offshore wave boundary conditions as discussed below. MIKE 21 SW (DHI, 2014a) simulates the growth, decay and transformation of wind-generated waves and swells in offshore and nearshore coastal areas. Taking this two-dimensional wave transformation model approach provided the beach profile and shoreline evolution models with more accurate wave data. The transformed wave data reflected the spatially varying wave heights and directions approaching the beaches as a result of influence from offshore shoals in the vicinity of the west of First Landing State Park and the Chesapeake Bay Bridge Tunnel (CBBT).

An existing MIKE 21 SW model developed by M&N was modified for this project and utilized to transform waves from offshore to the nearshore project area. The locations of various data sources applicable to the wave model development are shown in Figure 8. The model domain computational mesh resolution and model bathymetry are illustrated in Figure 9 through Figure 11 respectively. The model bathymetry was based on high resolution NOAA digital elevation model (DEM) data and NOAA nautical chart data. The high resolution of the data set and correlated high resolution of the model computational mesh resolves the navigation channels, the CBBT islands, and the complex nearshore bathymetry from Cape Henry to Little Creek Inlet in Virginia Beach.

The MIKE 21 SW model used NOAA hydrographic data, water level time series, and Atlantic Ocean wave boundary conditions, along with NOAA and USACE wind data, as inputs to the wave transformation simulations. The model has been calibrated by simulating Hurricane Irene (2011) wave conditions and comparing the model results to waves measured during Hurricane Irene at a wave gauge maintained by the City of Norfolk on its Ocean View shoreline as illustrated in Figure 8. The same model parameters were validated for the November 2009 nor’easter at the Norfolk wave gauge. Figure 12 and Figure 13 (respectively, for Hurricane Irene and the November 2009 nor’easter) illustrate the degree to which the wave transformation model agrees with the wave gauge data.

For the present study of Ocean Park Beach and Cape Henry Beach, the wave transformation model was modified to provide higher computational resolution and more detailed bathymetry in the project vicinity of project site. The updated model was run for storms including the November 2009 nor’easter, Hurricane Isabel (2003) and Hurricane Irene (2011), as well as for a continuous time series from 2009 through 2016. The storm simulations were used as input for the beach profile change modeling, and the 2009 to 2016 time series was used as input to the longshore transport and shoreline evolution modeling.



Figure 8: Wave, Wind, and Water Level Data Locations



Figure 9: MIKE 21 SW Wave Model Domain with Variable-resolution Computational Mesh



Figure 10: Variable-resolution Computational Mesh at Project Sites



Figure 11: MIKE 21 SW wave model domain with bathymetry in meters NAVD88



Figure 12: MIKE 21 SW model significant wave height at Norfolk wave gage and water levels at Sewells Point, Hurricane Irene

Figure 13: MIKE 21 SW model significant wave height at Norfolk wave gage and water levels at Sewells Point, 2009 nor’easter



4.2. USACE WIS Waves for Continuous Simulation: 2009 – 2016

Offshore wave and wind data were extracted from data sets of the Wave Information Studies (WIS). WIS is a USACE sponsored project that generates consistent hourly, long-term wave climates along all U.S. coastlines, including the Great Lakes and U.S. island territories. Unlike a forecast, a wave hindcast predicts past wave conditions using a computer model and observed wind fields. By using value-added wind fields, which combine ground and satellite wind observations, hindcast wave information is generally of greater accuracy than forecast wave conditions and is often representative of observed wave conditions.

The hindcast historical wave and wind data at WIS station 63197 as illustrated in Figure 14 were extracted and analyzed. Station 63197 is located at 36.92o latitude and -75.75o longitude in a water depth of approximately 56 feet. Wave and wind roses are illustrated in Appendix C of this report.

Figure 14: Historical Wave and Wind Data Location of WIS Station 63197



4.3. Typical Annual Nearshore Waves: 2009 – 2016

Waves were simulated for the consistent period from January 2009 through December 2016 to coincide with available shoreline positions for calibration/validation of the longshore transport and shoreline change simulations. USACE Atlantic WIS Station 63197 wave data was applied as an offshore open boundary condition, and the wind data at Station 63197 was applied over the entire model area. Model-simulated nearshore wave conditions were extracted along the 6.0 meter (19.7 feet) depth contours between Little Creek Inlet and the west of the First Landing State Park at points shown in Figure 15. The directional distribution of wave heights at location OC12 is shown in a rose plot as Figure 16.

The analyzed nearshore wave data, which include both storm and non-storm wave conditions, were utilized as representative wave conditions to evaluate long-term shoreline performance.

Figure 15: Nearshore Wave Data Locations



Figure 16: Wave Rose at Location OC12



4.4. Nearshore Storm Waves

For the historical storms used to simulate beach profile change, wave heights were extracted from the wave model results at the -6 m (-19.7 ft) depth contour point at the offshore ends of transects at Stations 10+00, 20+00, 40+00, 60+00 and 70+00 for Ocean Park Beach and Stations 115+00, 125+00, 135+00, 155+00, 160+00, and 185+00 for Cape Henry Beach for input to the SBEACH simulations. Figure 17 illustrates wave height distributions for November 2009 nor’easter.

Figure 17: Nearshore Wave Height Distributions for November 2009 nor’easter

The following figures illustrate the significant wave heights, peak wave periods, and stillwater elevations for each of the three storms simulated in SBEACH in this study.

Figure 18: Nearshore Wave and Water Level Conditions for the November 2009 Nor’easter at OC8



Figure 19: Nearshore Wave and Water Level Conditions for the November 2009 Nor’easter at OC12

Figure 20: Nearshore Wave and Water Level Conditions for the Hurricane Isabel (2003) at OC8



Figure 21: Nearshore Wave and Water Level Conditions for the Hurricane Isabel (2003) at OC12

Figure 22: Nearshore Wave and Water Level Conditions for the Hurricane Isabel (2003) with Storm Surge Water Levels Scaled to Peak at 1% Annual Chance Stillwater of +7.0 ft NAVD88 at OC8



Figure 23: Nearshore Wave and Water Level Conditions for the Hurricane Isabel (2003) with Storm Surge Water Levels Scaled to Peak at 1% Annual Chance Stillwater of +7.0 ft NAVD88 at OC12 Table 5: Storm Wave Height and Water Level Parameters at OC8 in SBEACH Simulations

Storm

Approximate Return Period of Peak Water Level (years)

Peak Significant

Wave Height, Hs

(ft)

Average Significant

Wave Height, Hs

(ft)

Peak Water Level

(ft, NAVD88)

Duration of Hs > 4 ft (hours)

Nor’easter November 2009 35 to 40 5.2 4.5 5.7 64

Hurricane Isabel September 2003 25 to 30 6.8 3.8 5.7 16

Hurricane Isabel September 2003

+ scaled 100-year water level

100 6.8 3.8 7.0 16


9859-06 Moffatt & Nichol | Beach Nourishment Template Conceptual Design 33

5. Beach Nourishment Template Conceptual Design

5.1. Introduction

This section presents the four alternative beach nourishment templates (i.e. beach / dune profiles to construct during future renourishment) evaluated in this study utilizing SBEACH and LITLINE model simulations. The SBEACH model was utilized to compute and compare storm responses for the four alternatives. The DHI LITLINE shoreline model was utilized to estimate shoreline change performance and thus likely renourishment intervals to maintain each of the alternatives.

5.2. Beach Nourishment Alternatives Development

The conceptual alternatives were designed using an assumed total volume of up to 150,000 cubic yards (cy) for Ocean Park Beach, and 200,000 cy for Cape Henry Beach of beach compatible sand that may be dredged from the Lynnhaven Inlet system on periodic cycles. The values were estimated to be a reasonable total volume for budgeting for the initial nourishment. The alternatives evaluated considered the relative benefits of a range of beach berm widths, dune elevations and placing a similar volume of sand per linear foot of beach versus placing more volume in more critically eroded stretches of the beach. The differences between the four alternatives are in the varying berm widths and dune heights and thus overall volume, as described below:

Alternative 1 includes construction of a beach berm at elevation +7.0 feet NAVD88. This berm elevation is a typical elevation used for prior City beach nourishment projects. The beach width at MHW from the existing beach is approximately 48 feet and 60 feet for Ocean Park Beach and Cape Henry Beach, respectively. The design berm width varies between 21 feet and 92 feet for Ocean Park Beach; and between 19 feet and 102 feet for Cape Henry Beach. The foreshore slope is approximately 15:1 ft/ft (H:V).

Alternative 2 differs from Alternative 1 in that beach width is intentionally varied along the reach showing greater risk from erosion. The berm width varies between 30 feet and 80 feet for Ocean Park Beach; and between 46 feet and 111 feet for Cape Henry Beach. The beach foreshore slope is approximately 15:1 ft/ft (H:V).

Alternative 3 includes both a constructed beach berm and a dune. The dune elevation is approximately +9.0 feet NAVD88, and the berm elevation is approximately +6.0 feet NAVD88. As in Alternative 2, the beach fill density is varied to place additional volume in areas showing greater risk from erosion. The dune slope is approximately 5:1. The foreshore slope is approximately 15:1 ft/ft (H:V).

Alternative 4 includes minimum beach fill volume to be required to resist the storm at 1% annual chance. The berm elevation is approximately +7.0 feet NAVD88. As in Alternative 2, the beach fill density is varied to place additional volume in areas showing greater risk from erosion. The foreshore slope is approximately 15:1 ft/ft (H:V).



The representative beach fill profiles for Alternatives 1 through 4 at Stations 10+00, 20+00, 40+00, 60+00 and 70+00 for Ocean Park Beach are illustrated in Figure 24 through Figure 28. The representative beach fill profiles for Alternatives 1 through 4 at Stations 115+00, 125+00, 135+00, 155+00, 160+00 and 185+00 for Cape Henry Beach are illustrated in Figure 29 through Figure 34.

Figure 24. Ocean Park Beach Fill Design Templates at Station 10+00











Figure 29. Cape Henry Beach Fill Design Templates at Station 115+00












5.3. Beach Profile Storm Response: Present Sea Levels

The beach profile response and the benefits provided by the beach and dune during coastal storms were evaluated utilizing the USACE SBEACH model for selected design storm events. SBEACH simulations were run for representative transects using beach profile data from Stations 10+00, 20+00, 40+00, 60+00 and 70+00 for Ocean Park Beach, and Stations 115+00, 125+00, 135+00, 155+00, 160+00 and 185+00 for Cape Henry Beach. These transects were selected as being representative of the generally distinct segments of Ocean Park Beach and Cape Henry Beach.

As no two of the beach profile survey data sets were located close enough in time to each other to facilitate model calibration (e.g. between pre- and post-storm profiles), SBEACH model parameters were based on experience using SBEACH for similar projects along nearby area beaches. The model parameters in Table 6 were used in the SBEACH profile change model simulations for this project.

Table 6: Parameters for the SBEACH Model

Parameter name Value

Effective grain size (mm)

Existing Ocean Park Beach 0.32 Existing Cape Henry Beach 0.51

Beach Nourishment 0.35 Landward surf zone depth (ft) 1.0 Max slope prior to avalanching 35

Overwash parameter 0.005 Transport Rate Coefficient (m4/N) 1.75e-6

Coefficient for Slope-dependent Term (m2/s) 0.002 Transport Rate Decay Coefficient Multiplier 0.5

Water temp (OC) 20

5.3.1. Ocean Park Beach

Appendix D contains charts of beach and dune profile erosion in the four representative storms are shown for each of the transects at Station 10+00, 20+00, 40+00, 60+00, and 70+00 at Ocean Park Beach for existing condition and the four beach fill templates. The results for existing conditions at Station 10+00, 20+00, and 70+00 are also shown in Figure 35 through Figure 37. The charts in these figures show the December 2016/October 2016 beach profile survey and the SBEACH simulation starting profile and the final eroded profiles for each of the four storms (solid color lines). The vertical line labeled “Seaward Parcel Line” indicates the approximate position of the most seaward structures in the reach represented by each transect. Similar charts for the four beach nourishment templates are in Appendix D.

Table 7 summarizes the key points regarding the beach and dune erosion for each of the SBEACH simulations in Ocean Park. In general, the November 2009 Nor’easter generated greater beach and dune erosion resulted in the most landward retreat of the dune at each transect. This appears to be mainly due to the very long duration of elevated water levels and wave heights that occurred during



that storm. In contrast, while Hurricane Isabel passed through the area with stronger winds and similar peak water levels and wave heights (as the November 2009 storm), it passed relatively quickly and thus did not generate day after day of dune erosion as was seen in the November 2009 storm.

For Ocean Park Beach, Alternative 4 provides a profile that would be expected to remain intact and continue to provide a measure of protection to structures in the design nor’easter and hurricane conditions.

Figure 35. Existing Condition SBEACH Simulation Results for Ocean Park Beach Station 10+00







Table 7: SBEACH Storm Erosion Results for Existing Conditions and Conceptual Alternative Templates at Present Sea Level for Ocean Park Beach

Stations Template November 2009 Nor’easter

Hurricane Isabel (2003)

Hurricane Isabel 2003 w/ Scaled

1% a.c. Peak SWL

10+00

Existing Condition

Erosion of dune crest; seaward-most structures threatened

Dune face erosion Erosion of dune crest; seaward-most structures threatened

Alt 1, Alt 2, Alt 3, Alt 4,

Significant berm erosion; dune face erosion

20+00

Existing Condition Significant dune face erosion



Significant berm erosion

40+00

Existing Condition Significant dune face erosion; dune fronting structures remains intact



60+00

Existing Condition Significant berm erosion; dune fronting structures remains intact



70+00

Existing Condition Significant dune face erosion





5.3.2. Cape Henry Beach

Appendix E contains charts of beach and dune profile erosion in the four representative storms are shown for each of the transects at Station 115+00, 125+00, 135+00, 155+00, 160+00 and 185+00 at Cape Henry Beach for existing condition and the four beach fill templates. The results for existing conditions at Station 135+00 and 155+00 are also shown in Figure 38 through Figure 39.

Table 8 summarizes the key points regarding the beach and dune erosion for each of the SBEACH simulations. For Cape Henry Beach, all alternatives provide protections to structures in the design nor’easter and hurricane conditions.

Figure 38. Existing Condition SBEACH Simulation Results for Cape Henry Beach Station 135+00



Figure 39. Existing Condition SBEACH Simulation Results for Cape Henry Beach Station 155+00



Table 8: SBEACH Storm Erosion Results for Existing Conditions and Conceptual Alternative Templates at Present Sea Level for Cape Henry Beach




1% a.c. Peak SWL

115+00

Existing Condition Berm erosion


Berm erosion

125+00

Existing Condition Dune face erosion; dune fronting structures remains intact



135+00

Existing Condition


Berm erosion Erosion of dune crest; seaward-most structures threatened



155+00

Existing Condition

Significant berm erosion; seaward-most structures threatened

Minor berm erosion Significant berm erosion; seaward-most structures threatened


Significant berm erosion Minor berm erosion Significant berm erosion

160+00

Existing Condition Minor berm erosion Minor berm erosion Significant berm erosion



185+00






5.4. Beach Profile Storm Response: With Sea Level Rise

This study’s scope included an evaluation of the effects of progressive mean sea level rise (i.e. relative sea level rise) on the level of protection afforded by the conceptual beach profile templates. In keeping with recommendations by VIMS (2013), this study considered the sensitivity of the beach profile performance to an assumed 1.5 feet of relative sea level rise over the next 30 to 50 years. The SBEACH model simulations were repeated with all of the water levels in each storm increased by 1.5 feet. The SBEACH results are presented in Appendix F and Appendix G, and key points are summarized in Table 9 and Table 10.

The primary effect of including 1.5 feet of sea level rise is to raise the elevation at which waves can attack the dune face. While this process resulted in greater erosion of the existing conditions profiles, the inclusion of 1.5 feet of sea level rise did not significantly alter the conclusion that any of the four alternatives evaluated would be acceptable at shoreline segment represented by Station 10+00. The additional erosion due to sea level rise would mean that less residual protection would remain following a significant storm, such that renourishment action may be needed in order to provide sufficient protection for “the next storm.”



Table 9: SBEACH Storm Erosion Results for Existing Conditions and Conceptual Alternative Templates with 1.5 feet SLR for Ocean Park Beach




1% a.c. Peak SWL

10+00

Existing Condition Significant dune erosion; seaward-most structures threatened


Significant berm erosion Erosion of dune crest; seaward-most structures threatened

20+00

Existing Condition

Significant dune erosion; seaward-most structures threatened

Erosion of dune crest Significant dune erosion; seaward-most structures threatened


Significant berm erosion Significant berm erosion Erosion of dune crest

40+00

Existing Condition Significant dune face erosion; dune fronting structures remains intact


Dune face erosion; erosion of dune crest

60+00

Existing Condition Erosion of dune crest; dune fronting structures remains intact


Dune face erosion; significant berm erosion

70+00

Existing Condition


Erosion of dune crest Significant dune erosion; seaward-most structures threatened


Erosion of dune crest; significant berm erosion



Table 10: SBEACH Storm Erosion Results for Existing Conditions and Conceptual Alternative Templates with 1.5 feet SLR for Cape Henry Beach




1% a.c. Peak SWL

115+00

Existing Condition Dune face erosion; berm erosion; dune fronting structures remains intact


Dune face erosion; significant berm erosion

125+00

Existing Condition Significant dune erosion Berm erosion Significant dune erosion



135+00

Existing Condition


Berm erosion Erosion of dune crest; seaward-most structures threatened



155+00

Existing Condition


Minor berm erosion Significant dune erosion; seaward-most structures threatened



160+00

Existing Condition Berm erosion Berm erosion Dune face erosion


Significant berm erosion Significant berm erosion Dune face erosion

185+00





9859-06 Moffatt & Nichol | Longshore Sediment Transport and Shoreline Evolution 50

6. Longshore Sediment Transport and Shoreline Evolution

Each of the four conceptual beach nourishment profile alternatives is associated with a different mean tide level shoreline position. Thus, the rate of shoreline retreat and timeframe for future renourishment varies among the different alternatives. The LITLINE shoreline evolution model (within DHI’s LITPACK suite) was utilized to evaluate the shoreline performance of the proposed beach nourishment projects. LITLINE calculates the shoreline position based on input of the wave climate as a time series. The model is based on a one-line approach to shoreline change simulation, in which the cross-shore profile is assumed to remain unchanged, and the entire profile shape is shifted landward and bayward during beach erosion and accretion, respectively. Thus, the coastal morphology is solely described by the coastline position (cross-shore direction) and the representative coastal profile at a given long-shore position. The model also includes the effects of structures such as groins, jetties, revetments, detached breakwaters, sources and sinks.

The LITLINE model was calibrated and validated based on the historical shoreline changes, along with evaluation of the model simulated longshore sediment transport rates.

6.1. LITLINE Model Setup

Two LITLINE models were developed for Ocean Park Beach and Cape Henry Beach, respectively. For Ocean Park Beach, the LITLINE model domain covers the shoreline from the western shoreline of Lynnhaven Inlet to the Joint Expeditionary Base Little Creek in the west. The total shoreline length simulated within the LITLINE model for the Ocean Park Beach nourishment project is approximately 4.8 miles. For Cape Henry Beach, the LITLINE model domain covers the shoreline from the eastern shoreline of Lynnhaven Inlet to the western portion of First Landing State Park. The total shoreline length simulated within the LITLINE model for the Cape Henry Beach nourishment project is approximately 2.2 miles. The shoreline at mean tide level (MTL, -0.27 feet NAVD88) was represented by grid points with spacing of 16.4 feet (5 m) in the alongshore direction.

For Ocean Park Beach, representative cross-shore profiles were created for input to LITLINE by averaging the profiles in April 2013, December 2014, December 2015 and December 2016 at Ocean Park Beach profile stations 5+00, 20+00, 40+00, 60+00 and Chesapeake Beach survey profile station 0+00. For Cape Henry Beach, representative cross-shore profiles were created by averaging the profiles in July 2013, October 2015 and October 2016 at profile stations 115+00, 125+00, 140+00, 160+00, and 185+00. The wave climates from the wave transformation model at water depth of 19.7 feet (6 m) were utilized as the time-series wave open boundary conditions. The dune positions and the dune heights were extracted from the survey profiles. Additional input parameters of the LITLINE models are summarized in Table 11.



Table 11: LITLINE Model Setup Parameters

No. Parameter Name Value

1 Angle of normal to baseline 90ON 2 Height of active beach 9.8 feet (3.0 m)

3 Mean grain size

Existing Ocean Park Beach 0.32 (mm) Existing Cape Henry Beach 0.51 (mm)

Beach Nourishment 0.35 (mm) 4 Roughness 0.013 feet (0.004 m) 5 Maximum active length 4124 feet (1257 m) 6 Maximum Courant number 1 7 Crank-Nicolson factor 0.25

6.2. LITLINE Model Calibration/Validation for Ocean Park Beach

To properly predict the shoreline performances for the Ocean Park Beach nourishment project, the LITLINE model was verified by comparison against historical shoreline behavior. For calibration of the LITLINE model, the December 2014 shoreline position was chosen as the initial shoreline location and the December 2015 position was chosen as the final shorelines. Model parameters were adjusted until reasonable longshore transport rates and gradients were produced and an acceptable match was achieved between the model-predicted final shoreline and the December 2015 observed shoreline.

Comparing the alongshore sediment transport rates during December 2014 and December 2015 provides an initial check of the reasonableness of the shoreline change modeling. Figure 40 presents the model-simulated longshore sediment transport rate at Ocean Park Beach shoreline. Negative alongshore transport values are directed westward, and positive value are directed eastward. Near transect 45+00, the alongshore sediment transport started from west to east, with sediments eventually transported into Lynnhaven Inlet. The simulated alongshore sediment transport rates at Ocean Park shoreline varied spatially between approximately -20,000 cy/yr and 30,000 cy/yr during December 2014 and December 2015.

Figure 41 presents the comparison between the observed (“2015-Measured”) and LITLINE simulated (“2015-Calculated”) shoreline changes during December 2014 and December 2015. The simulated shoreline erosion and deposition locations and magnitudes are in good agreement with the observed shoreline changes at most locations along Ocean Park Beach.

The shoreline evaluation model was validated using the calibrated shoreline evaluation model parameters. Figure 42 presents the comparison between the observed (“2013-Measured”) and LITLINE simulated (“2013-Calculated”) shorelines during May 2012 and May 2013. The simulated shoreline changes are in good agreement with the observed shoreline changes for the model validation.



Figure 40: Longshore Sediment Transport Rate at Ocean Park Beach (December 2014 to December 2015)

Figure 41: Comparison between Measured and Calculated Shoreline Changes at Ocean Park Beach (December 2014 to December 2015)



Figure 42: Comparison between Measured and Calculated Shoreline Changes at Ocean Park Beach (May 2012 to May 2013)

6.3. LITLINE Model Calibration/Validation for Cape Henry Beach

For Cape Henry Beach, the LITLINE model was verified by comparison against historical shoreline behavior. For calibration of the LITLINE model, the June 2014 shoreline position was chosen as the initial shoreline location and the October 2015 position was chosen as the final shorelines. Model parameters were adjusted until reasonable longshore transport rates and gradients were produced and an acceptable match was achieved between the model-predicted final shoreline and the July 2013 observed shoreline.

Comparing the alongshore sediment transport rates during June 2014 and October 2015 provides an initial check of the reasonableness of the shoreline change modeling. Figure 43 presents the model-simulated longshore sediment transport rate along Cape Henry Beach shoreline. Negative alongshore transport values are directed westward. The simulated alongshore sediment transport rates at Cape Henry shoreline vary between approximately -5,000 cy/yr and -40,000 cy/yr during June 2014 and October 2015.

Figure 44 presents the comparison between the observed (“2015-Measured”) and LITLINE simulated (“2015-Calculated”) shoreline changes during June 2014 and October 2015. The simulated shoreline erosion and deposition locations and magnitudes are in general good agreement with the observed shoreline changes at most locations along the Cape Henry Beach shoreline.



The shoreline evaluation model was validated using the calibrated shoreline evaluation model parameters. Figure 45 presents the comparison between the observed (“2013-Measured”) and LITLINE simulated (“2013-Calculated”) shorelines during March 2012 and July 2013. The simulated shoreline locations are in general good agreement with the observed shoreline changes for the model validation.

Figure 43: Longshore Sediment Transport Rate at Cape Henry Beach (June 2014 to October 2015)

Figure 44: Comparison between Measured and Calculated Shoreline Changes at Cape Henry Beach (June 2014 to October 2015)



Figure 45: Comparison between Measured and Calculated Shoreline Changes at Cape Henry Beach (March 2012 to July 2013)

6.4. Beach Nourishment Template Alternatives’ Shoreline Evolution

Based on the observed agreement between the model predicted alongshore sediment transport rates, shoreline positions and shoreline changes, the calibrated LITLINE model served to establish the littoral process model of the proposed beach nourishment project for the evaluations of project shoreline performances.

Using the calibrated LITLINE model and the SBEACH model, the long-term shoreline change performances were evaluated and analyzed for the separate Alternatives 1, 2 and 4 for Ocean Park Beach and Cape Henry Beach. Alternative 2 and Alternative 3 have same initial shoreline position (varying only in terms of enhancement to the dune), and the simulated shoreline performance will be same for the two alternatives. The simulated shoreline performances are illustrated in Appendix H and Appendix I for Ocean Park Beach and Cape Henry Beach, respectively.

For Ocean Park Beach, the shoreline performances for Alternative 4 are illustrated in Figure 46. The most rapid shoreline retreat is seen approximately between Stations 10+00 and 20+00, and between Stations 65+00 and 75+00. The shoreline between Stations 25+00 and 40+00 is relatively stable. The simulated shoreline performances after two years post-nourishment are shown in Figure 47. The better beach performances are provided by Alternative 4.



For Cape Henry Beach, the shoreline performances for Alternative 4 are illustrated in Figure 48. The most rapid shoreline retreat is seen approximately between Stations 115+00 and 145+00. The shoreline between Stations 175+00 and 200+00 is relatively stable. The simulated shoreline performances after two years post-nourishment are shown in Figure 49. The better beach performance is provided by Alternative 4.



Figure 46: Shoreline Performance for Alternatives 4 for Ocean Park Beach



Figure 47: LITLINE Shoreline Evolution in Two Years Post-Nourishment for Alternatives 1 through 4 for Ocean Park Beach



Figure 48: Shoreline Performance for Alternatives 4 for Cape Henry Beach



Figure 49: LITLINE Shoreline Evolution in Four Years Post-Nourishment for Alternatives 1 through 4 for Cape Henry Beach


9859-06 Moffatt & Nichol | Recommended Conceptual Design Template 61

7. Recommended Conceptual Design Template

From the storm-induced profile evolution (SBEACH) and longshore-transport driven shoreline evolution (LITLINE) analyses discussed above for the four separate alternatives, the recommended conceptual design templates were developed.

The SBEACH simulations for the four initial profile alternatives provided a first indication of the beach width2 needed to provide protection from waves and surge. The beach width fronting the existing or created dune feature dissipates wave energy before the waves strike the dune, reducing dune erosion and wave runup and overwash potential.

7.1. Minimum Beach Berm Width at Each Station

Alternative 4 was developed for the minimum beach fill volume to be required to resist the storm at November 2009 Nor’easter and/or 1% annual chance. Table 12 summarizes the associated minimum distance between existing structures and the MTL shoreline for protecting against impacts of surge and waves on structures in the two most intense of the simulated storms.

Table 12: Minimum Distance between MTL Shoreline and Existing Structures at Present Sea Levels

Beach Station Minimum Distance Between MTL and

Structures (feet)

Ocean Park Beach 10+00 199 20+00 230 70+00 220

Cape Henry Beach 135+00 199 155+00 162

7.2. Advance Nourishment and Estimated Renourishment Interval

In addition to minimum beach berm from Alternative 4, this Recommended Conceptual Design includes the provision of additional beach berm width as advance nourishment. The purpose of advance nourishment is to allow for a sufficient minimum design beach and dune cross-section – for storm surge and wave protection – to remain in the face of typical annual shoreline retreat between planned renourishment events. The required advance nourishment was first estimated as additional beach berm width required to keep up with recent historical and model-simulated erosion rates at each station. The LITLINE model was then used to investigate how rapidly the shoreline and beach berm – including the design profiles plus advance nourishment – would retreat following the initial nourishment project construction. The post-construction shoreline evolution results from the LITLINE simulations are shown for the Recommended Conceptual Design in Figure 50 and Figure 51.

2 This beach berm width is defined as the distance between the intersection of the dune toe with the beach berm at +6 feet NAVD88 and the MTL shoreline.



Figure 50: LITLINE Shoreline Evolution for Recommended Conceptual Design Including Advance Nourishment (Ocean Park Beach)



Figure 51: LITLINE Shoreline Evolution for Recommended Conceptual Design Including Advance Nourishment (Cape Henry Beach)



From inspection of the LITLINE simulated post-construction shoreline evolution, a planned nourishment interval was estimated based on the time over which the shoreline is expected to retreat to the minimum position for maintaining the design level of protection. Table 13 documents the LITLINE-simulated retreat of the MTL shoreline in two-year intervals following construction of the Recommended Conceptual Design (which includes the advance nourishment). The values in the table are the distance between the simulated shoreline and the existing structures at each station, and these values are compared to the minimum distance required for the remaining cross-section to protect against specific design storms.

Table 13: Distance between the MTL shoreline and the Existing Structures for Alternative 4

Beach Station Initial

Position (ft)

After 2 Years

(ft)

After 4 Years

(ft)

After 6 Years

(ft)

Ocean Park Beach

10+00 261 224 196 167 20+00 319 191 154 113 70+00 170 108 69 46

Cape Henry Beach

135+00 389 264 196 132 155+00 182 178 180 178

The yellow shading Table 13 indicates the time post-construction that the shoreline retreated to the minimum position identified in Table 12. In the hot spot area within four years post-construction the simulated MTL shoreline retreated to this minimum distance for storm protection against a storm like the November 2009 Nor’easter.

The LITLINE results indicate that maintaining protection would require a renourishment event approximately four years.

7.3. Recommended Conceptual Design Profiles

The Recommended Conceptual Design profile templates for each station, including advance nourishment for the initial construction, are shown as cross-section plots in Appendix J and Appendix K. A description of the recommended profile at each station is given in Table 14 and Table 15. Table 16 and Table 17 summarize the required nourishment profile volumes at each station (cy/ft), reach volumes between pairs of stations (cy) and the total volume (cy) required to construct the Recommended Conceptual Design. For Ocean Park Beach, a total placed volume of approximately 294,000 cubic yards is required to construct the Recommended Conceptual Design, including advance nourishment. For Cape Henry Beach, a total placed volume of approximately 245,000 cubic yards is required to construct the Recommended Conceptual Design, including advance nourishment.



Table 14: Description of Recommended Conceptual Beach Nourishment Design Profiles along Ocean Park Beach


Advance Nourishment Beyond Min. Berm

5+00 - - 10+00 70 feet 62 feet 15+00 90 feet 110 feet 20+00 80 feet 79 feet 25+00 60 feet 40 feet 30+00 80 feet 10 feet 35+00 70 feet 10 feet 40+00 50 feet 10 feet 45+00 40 feet 20 feet 50+00 50 feet 20 feet 55+00 50 feet 20 feet 60+00 70 feet 20 feet 65+00 70 feet 20 feet 70+00 70 feet 20 feet 75+00 - -



Table 15: Description of Recommended Conceptual Beach Nourishment Design Profiles along Cape Henry Beach


Advance Nourishment Beyond Min. Berm

105+00 - - 110+00 15 feet 20 feet 115+00 35 feet 20 feet 120+00 30 feet 20 feet 125+00 35 feet 27 feet 130+00 80 feet 170 feet 135+00 70 feet 190 feet 140+00 50 feet 122 feet 145+00 44 feet 59 feet 150+00 55 feet 20 feet 155+00 30 feet 20 feet 160+00 35 feet 20 feet 165+00 20 feet 20 feet 170+00 40 feet 13 feet 175+00 25 feet 11 feet 180+00 35 feet 5 feet 185+00 35 feet 0 feet 190+00 20 feet 0 feet 195+00 25 feet 0 feet 200+00 - -



Table 16: Fill Volumes for Constructing Recommended Conceptual Beach Nourishment Design for Ocean Park Beach

No. Section Fill Density (cy/ft) Total Fill Volume (cy)

5+00 0.0

294,000

10+00 62.7 15+00 114.2 20+00 77.9 25+00 41.6 30+00 33.6 35+00 30.0 40+00 29.9 45+00 38.8 50+00 31.1 55+00 26.7 60+00 25.2 65+00 39.3 70+00 37.1 75+00 0.0



Table 17: Fill Volumes for Constructing Recommended Conceptual Beach Nourishment Design for Cape Henry Beach

No. Section Fill Density (cy/ft) Total Fill Volume (cy)

105+00 0.0

245,000

110+00 19.9 115+00 20.4 120+00 26.7 125+00 15.5 130+00 116.7 135+00 111.4 140+00 54.6 145+00 25.3 150+00 18.7 155+00 28.4 160+00 15.5 165+00 16.8 170+00 1.8 175+00 1.1 180+00 1.8 185+00 0.8 190+00 0.9 195+00 2.9 200+00 0.0


9859-06 Moffatt & Nichol | Conclusions and Recommendations 69

8. Conclusions and Recommendations

M&N was retained by the City to provide a study and conceptual engineering designs of alternative beach profile templates for sand nourishment at Ocean Park Beach and Cape Henry Beach. The goal of the project is to enhance the resilience of the shoreline protection of coastal infrastructure to storm events such a severe nor’easter or hurricane. The project’s objective was to provide a beach profile template for construction that effectively balances shoreline advancement (with associated recreational beach width) with dune height and dune volume for a realistic total nourishment volume.

Available data was compiled and analyzed, which included: historical beach profile and shoreline position, aerial photography, hydrographic data, publicly available wave, current, tide, and wind data, and prior coastal engineering studies. Four beach nourishment alternatives were developed that consisted of varying combinations of beach width, beach berm elevation, dune crest elevation and beach renourishment intervals.

A target equilibrium profile volume for the four alternatives ranged between 154,000 cy and 184,000 cy for Ocean Park Beach, and between 93,000 cy and 223,000 cy for Cape Henry Beach. The Recommended Conceptual Designs include advance nourishment such that a total volume of approximately 293,900 would be required to construct the beach nourishment project for Ocean Park Beach, and approximately 244,200 would be required to construct the beach nourishment project for Cape Henry Beach. The sand in the selected borrow source for any given initial or maintenance nourishment project will need to consider an overfill ratio associated with the sand characteristics of the specific borrow source selected.

Beach profile storm response for four initial alternative profile templates was estimated using the SBEACH model simulations for a severe historical nor’easter, a severe historical hurricane, and a major hurricane based on Hurricane Isabel. Five typical beach profiles – taken at Stations 10+00, 20+00, 40+00, 60+00 and 70+00 along the survey baseline – were used in the SBEACH analysis to represent distinct segments of Ocean Park Beach. Six typical beach profiles – taken at Stations 115+00, 125+00, 135+00, 155+00, 160+00 and 185+00 along the survey baseline – were used in the SBEACH analysis to represent distinct segments of Cape Henry Beach.

A shoreline change model using the LITLINE software was developed, calibrated and verified utilizing historical shoreline change data and (secondarily) by comparison of results with historical longshore sediment transport rate. The calibrated LITLINE model was applied to evaluate shoreline retreat rate and anticipated shoreline position for the nourishment alternative templates.

After review of the performance of the initial four alternative beach profile templates, the Recommended Conceptual Design was developed by applying a mixture of the four alternative to different segments of Ocean Park Beach and Cape Henry Beach. Advance nourishment was considered and an approximate renourishment interval was evaluated. Specific conclusions and recommendations follow.



8.1. Conclusions

• Ocean Park Beach and Cape Henry Beach are moderately eroding coastal areas that are susceptible to significant cross-shore profile erosion during storm waves approaching from the Northeast quadrant.

• For Ocean Park Beach, during the period of December 2014 to December 2015, the MHW shoreline change was approximately -16.7 ft/yr. The average volumetric change above -11 feet NAVD88 during this same time period is approximately -20.2 cy/ft/yr.

• For Cape Henry Beach, during the period of March 2012 to June 2013, the MHW shoreline change was approximately -10.5 ft/yr. The average volumetric change above -5 feet NAVD88 during this same time period is approximately -4.1 cy/ft/yr.

• For Ocean Park Beach, at Stations 10+00, 20+00 and 70+00, the existing beach does not provide sufficient storm protection for the upland structures for the storms simulated. Alternatives 2 and 3 profile templates would provide greater reduction of storm erosion risk to the bulkheads and other structures. Alternative 4 profile template would provide the minimum reduction of storm erosion risk to the bulkheads and other structures.

• For Cape Henry Beach, at Stations 135+00 and 155+00, the existing beach does not provide sufficient storm protection for the upland structures for the storms simulated. Alternatives 2 and 3 profile templates would provide greater reduction of storm erosion risk to the bulkheads and other structures. Alternative 4 profile template would provide the minimum reduction of storm erosion risk to the bulkheads and other structures.

8.2. Recommendations

It is recommended that the conceptual Ocean Park Beach nourishment design and the conceptual Cape Henry Beach nourishment design should include a variable profile construction template, in order to focus on adding a substantial dune and dry beach width to the hot spot area. The specific design profile characteristics, including advance nourishment, are shown graphically as profile plots in Appendix J and Appendix K. These recommendations assume an existing, pre-construction beach condition similar to the December 2016 survey profiles.

Table 16 documents the required nourishment profile volumes at each station, which sum to a total volume of approximately 294,000 cubic yards required to construct the Recommended Conceptual Design, including advance nourishment for Ocean Park Beach.

Table 17 documents the required nourishment profile volumes at each station, which sum to a total volume of approximately 245,000 cubic yards required to construct the Recommended Conceptual Design, including advance nourishment for Cape Henry Beach.

It is expected that the shoreline position in the erosional hotspot areas, between the identified stations, is likely to retreat to a minimum position for continuing provision of the desired storm protection



within four years post-construction. It is recommended that the City plan and budget for a nourishment at these hotspot areas in Ocean Park Beach and Cape Henry Beach approximately every four years.

It is noted that these estimates are based on typical annual historical wave conditions. Occurrence of a particularly severe or prolonged coastal storm event, or greater than typical frequency of storms in time period post-construction, would likely accelerate the need for renourishment and could increase the volume requirements to restore design conditions.


9859-06 Moffatt & Nichol | References 72

9. References

FEMA, 2015. Flood Insurance Study, City of Virginia Beach, Virginia. Flood Insurance Study Number 515531V000B. Federal Emergency Management Agency, Washington, D.C. January 16, 2015.

BWAC, 2002. Virginia Beach, Beach Management Plan. Beaches and Waterways Advisory Commission. April, 2002.

Basco, D.R., 2003. Chesapeake Bay Shoreline Study, City of Virginia Beach. Technical Report. Beach Consultants, Inc. Norfolk, Virginia.

DHI, 2014. MIKE21, Spectral Wave Module, Scientific Documentation. Technical Report. Danish Hydraulic Institute (DHI).

DHI, 2014. LITLINE, Coastline Evolution, LITLINE User Guide. Technical Report. Danish Hydraulic Institute (DHI).

Larson, M. and N.C. Kraus, 1989. SBEACH Report 1: Empirical Foundation & Model Development. Technical Report TR CERC-89-9. Coastal Engineering Research Center (CERC), Waterways Experiment Station, U.S. Army Engineering Research and Development Center, Vicksburg, Mississippi. July 1989.

Larson, M., N.C. Kraus, M.R. Byrnes, 1990. SBEACH Report 1: Numerical Formulation & Model Tests. Technical Report TR CERC-89-9. CERC. May 1990.

Larson, M., R.A. Wise, N.C. Kraus, 2004. Coastal Overwash, Part 2: Upgrade to SBEACH. ERDC/RSM-TN-15. CERC. September 2004.

Moffatt & Nichol, 2016. Chesapeake Beach Nourishment Template Design – Conceptual Engineering Designs. Technical Report. October 2016.

USACE, 2002. Coastal Engineering Manual. Engineer Manual 1110-2-1100, U.S. Army Corps of Engineers, Washington, D.C. (in 6 volumes).

VIMS, 2011. A Geotechnical Evolution of Chesapeake Beach Shoal for Beach Quality Sand. Shoreline Studies Program, Department of Physical Sciences, Virginia Institute of Marine Science, College of William & Mary, Virginia, December 2011.

VIMS, 2012. Shoreline Evolution: City of Virginia Beach, Virginia, Chesapeake Bay, Lynnhaven River, Broad bay and Atlantic Ocean Shorelines. Virginia Institute of Marine Science, College of William & Mary, Virginia, December 2012.

WS&E, 2015. Chesapeake Beach, Virginia Beach, Beach Monitoring Report, September 2010 to May 2015. Waterway, Surveys & Engineering, Ltd. Virginia Beach, Virginia.


9859-06 Moffatt & Nichol | Appendix A: Beach Profile Location and Historical Beach Profiles (Ocean Park Beach)

Appendix A: Beach Profile Location and Historical Beach Profiles (Ocean Park Beach)


9859-06 Moffatt & Nichol | Appendix B: Beach Profile Location and Historical Beach Profiles (Cape Henry Beach)

Appendix B: Beach Profile Location and Historical Beach Profiles (Cape Henry Beach)


9859-06 Moffatt & Nichol | Appendix C: Wave and Wind Roses at WIS Station 63197

Appendix C: Wave and Wind Roses at WIS Station 63197


9859-06 Moffatt & Nichol | Appendix D: SBEACH Storm Erosion Results with Present Sea Level (Ocean Park Beach)

Appendix D: SBEACH Storm Erosion Results with Present Sea Level (Ocean Park Beach)


9859-06 Moffatt & Nichol | Appendix E: SBEACH Storm Erosion Results with Present Sea Level (Cape Henry Beach)

Appendix E: SBEACH Storm Erosion Results with Present Sea Level (Cape Henry Beach)


9859-06 Moffatt & Nichol | Appendix F: SBEACH Storm Erosion Results with 1.5 Feet of SLR (Ocean Park Beach)

Appendix F: SBEACH Storm Erosion Results with 1.5 Feet of SLR (Ocean Park Beach)


9859-06 Moffatt & Nichol | Appendix G: SBEACH Storm Erosion Results with 1.5 Feet of SLR (Cape Henry Beach)

Appendix G: SBEACH Storm Erosion Results with 1.5 Feet of SLR (Cape Henry Beach)


9859-06 Moffatt & Nichol | Appendix H: LITLINE Shoreline Evolution Results (Ocean Park Beach)

Appendix H: LITLINE Shoreline Evolution Results (Ocean Park Beach)


9859-06 Moffatt & Nichol | Appendix I: LITLINE Shoreline Evolution Results (Cape Henry Beach)

Appendix I: LITLINE Shoreline Evolution Results (Cape Henry Beach)


9859-06 Moffatt & Nichol | Appendix J: Recommended Conceptual Design Profiles Including Advance Nourishment (Ocean Park Beach)

Appendix J: Recommended Conceptual Design Profiles Including Advance Nourishment (Ocean Park Beach)


9859-06 Moffatt & Nichol | Appendix K: Recommended Conceptual Design Profiles Including Advance Nourishment (Cape Henry Beach)

Appendix K: Recommended Conceptual Design Profiles Including Advance Nourishment (Cape Henry Beach)

Documents

FY 2019-2020 Virginia Beach Budget Response to Council ...€¦ · Figure 12: MIKE 21 SW model significant wave height at Norfolk wave gage and water levels at Sewells Point, Hurricane