OCS Report 

 MMS 2001-089 

DEVELOPMENT AND DESIGN OF BIOLOGICAL AND PHYSICAL MONITORING 

PROTOCOLS TO EVALUATE THE LONG-TERM IMPACTS OF OFFSHORE 

DREDGING OPERATIONS ON THE MARINE ENVIRONMENT 

Prepared for: 

International Activities and Marine Minerals Division 

Minerals Management Service 

U.S. Department of Interior 

Herndon, Virginia 

Prepared by: 

Research Planning, Inc. 

Columbia, South Carolina 

W.F. Baird & Associates Ltd. 

Madison, Wisconsin 

Applied Marine Sciences, Inc. 

Livermore, California 

October 2001 
ii 

DISCLAIMER 

This report has been reviewed by the Minerals Management Service and approved for 

publication. Approval does not signify that the contents necessarily reflect the views and policies 

of the Service, nor does mention of trade names or commercial products constitute endorsement 

or recommendation for use. 
iii 

TABLE OF CONTENTS 

1.0 PROJECT INTRODUCTION.............................................................................................. 1

2.0 PROJECT OVERVIEW ...................................................................................................... 3 

2.1 Description of Borrow Sites ......................................................................................... 6

 2.2 Summary .................................................................................................................... 17 

3.0 PROJECT APPROACH .................................................................................................... 18 

3.1 Resource Management and Stewardship Goals .......................................................... 18 

 3.1.1 Goals................................................................................................................ 18 

 3.1.2 Questions ......................................................................................................... 18 

 3.1.3 Assumptions:.................................................................................................... 18 

3.2 Literature Review....................................................................................................... 19

3.3 Ecological Issues of Concern...................................................................................... 19 

 3.3.1 Geophysical Environment and Processes ......................................................... 20 

 3.3.2 Biological Ecosystems ..................................................................................... 24 

3.4 Geophysical and Biological Parameters Addressed by the Monitoring Program........ 26 

 3.4.1 Physical Monitoring Program........................................................................... 26 

 3.4.2 Biological Monitoring Program ....................................................................... 30 

4.0 MONITORING PROTOCOLS.......................................................................................... 31 

4.1 Biological Protocol Approach .................................................................................... 34 

4.2 Temporal Sampling Requirements ............................................................................. 35 

5.0 ADAPTIVE MANAGEMENT.......................................................................................... 76

6.0 COST ANALYSIS ............................................................................................................ 78

6.1 Physical Program Elements ........................................................................................ 78 

 6.1.1 Hydrographic Surveys...................................................................................... 79

 6.1.2 Wave Monitoring and Modeling ...................................................................... 80 

 6.1.3 Shoreline Monitoring and Modeling ................................................................ 81 

 6.1.4 Grain Size Analysis.......................................................................................... 82 

 6.2 Biological Program Elements..................................................................................... 82 

 6.2.1 Benthic Field Sampling and Analysis............................................................... 82 

 6.2.2 Fish Field Samling and Analysis...................................................................... 83 

 6.2.3 Stable Isotope Analysis .................................................................................... 84 

 6.2.4 Data Analysis and Reporting............................................................................ 85 

 6.3 Summary of Estimated Costs...................................................................................... 85 

7.0 INFORMATION GAPS .................................................................................................... 88 

7.1 Characteristics of OCS Shelf Sand Ridges and Shoals ............................................... 89 

 7.1.1 Definitions and Occurences.............................................................................. 89

 7.1.2 Theories for Origin........................................................................................... 91 

 7.1.3 Future Formation and Mobility of the Ridge Features.................................... 102 
iv 

 7.1.4 Impact of Dredging ........................................................................................ 102 

 7.1.5 Biological Factors .......................................................................................... 103 

 7.1.6 Summary ....................................................................................................... 103 

8.0 DATA MANAGEMENT................................................................................................... 52

9.0 LITERATURE CITED ...................................................................................................... 54 

APPENDIX A ......................................................................................................................... A-1 
v 

LIST OF FIGURES 

Figure 2.1 Project organization chart and responsibilities ...................................................... 4 

Figure 2.2 Locations of identified OCS borrow sites ............................................................. 7 

Figure 2.3 Deposits offshore of New Jersey........................................................................... 8 

Figure 2.4 Bathymetry offshore of Northern Maryland showing three borrow sites............... 9 

Figure 2.5 Bathymetry offshore of Southern Virginia.......................................................... 11 

Figure 2.6 Perspective view showing inner shelf of proposed borrow deposits inshore and 

offshore of the three mile limit, Dare County, NC .............................................. 12 

Figure 2.7 Analyses of records within three and five miles of erosional beaches that met 

certain criteria on bottom-type sediment composition and sediment thickness. 

Offshore South Carolina...................................................................................... 14 

Figure 2.8 Possible Federal reserves offshore East-Central Florida ..................................... 15 

Figure 2.9 Identified borrow sites offshore Alabama ........................................................... 16 

Figure 2.10 Location of the Ship Shoal deposit offshore Louisiana ....................................... 17 

Figure 3.1 Interactions between key physical and biological parameters for OCS 

 sand mining......................................................................................................... 20 

Figure 4.1 Curve that indicates more than approximately 10 replicates would provide 

 smaller reductions in standard error for each additional replicate.................................... 39 

Figure 7.1 Sand swells on continental shelf from New York to Cape Kennedy ................... 89 

Figure 7.2 Bathymetry of the Assateague ridge field, contoured from National 

 Ocean Survey Smooth sheets .............................................................................. 92 

Figure 7.3 Study area in the northeastern Gulf of Mexico showing detailed bathymetry 

 at 5m contour intervals........................................................................................ 93 

Figure 7.4 (A) Bathymetry (in meters) of the area surround Sable Island, with crestline 

 positions of the shoreface-attached ridges and locations of morphological zones 

 discussed in the text (B) Location of grain-size transects, sidescan and seismic 

 profiles, and vibrocores shown in subsequent figures ......................................... 93 

Figure 7.5 Trends in texture of surficial sediments over shoreface sand ridges. A) Sable 

 Island, Nova Scotia. B) Peahala Ridge, New Jersey........................................... 94 

Figure 7.6 Storm and fair-weather dynamics and ridge migration in nearshore and offshore 

 areas.................................................................................................................... 94 

Figure 7.7 Orientation of near-bottom, peak storm current and wave motion 30-31 March 

 1985. Current meters V1 and V2, which are located outside map area, 

 are shown for reference....................................................................................... 95 

Figure 7.8 Schematic diagram of secondary flow motions (helical flow structure) and storm 

 wave surge believed to be associated with storm flow field ................................ 96 

Figure 7.9 Evolution of ridges on the New Jersey Atlantic Shelf, USA ............................... 97 

Figure 7.10 Schematic diagram of ridge classes..................................................................... 98 

Figure 7.11A Bathymetry of shoals offshore Maryland-Delaware border (depths and x-y axes 

 in meters) ............................................................................................................ 99 

Figure 7.11B Wave heights predicted by a Boussinesq wave model for shoals offshore of the 

 Maryland/Delaware border (incoming wave: Hs=1 m, Tp=16s, ENE).............. 100 

Figure 7.11C 3D View of 3 Shoals ......................................................................................... 101 
vi 

LIST OF TABLES 

Table 2.1 New Jersey OCS borrow sites............................................................................... 8 

Table 2.2 Maryland/Delaware OCS borrow sites.................................................................. 9 

Table 2.3 Virginia OCS borrow sites .................................................................................. 10 

Table 2.4 North Carolina OCS borrow sites........................................................................ 12 

Table 2.5 South Carolina OCS borrow sites........................................................................ 13 

Table 2.6 Florida OCS borrow sites.................................................................................... 13 

Table 2.7 Louisiana OCS borrow sites................................................................................ 16 

Table 2.8 Louisiana OCS borrow sites................................................................................ 17 

Table 3.1 Summary of potential physical and biological effects of OCS sand mining 

 for beach replenishment ...................................................................................... 21 

Table 3.2 Summary of requirements of the physical monitoring protocols ......................... 28 

Table 3.3 Summary of requirements of the biological monitoring protocols ...................... 32 

Table 4.1 Processes to be considered for various model domains....................................... 56 

Table 4.2 Capabilities of spectral wave transformation models .......................................... 57 

Table 4.3 Capabilities of phase-resolving wave transformation models.............................. 58 

Table 4.4 Summarized general bathymetric survey criteria................................................. 63 

Table 4.5 Comparison of acceptable bathymetric survey systems....................................... 64 

Table 6.1 Low and high cost estimates for the designed monitoring program, for 

 pre-dredging, immediate post-dredging, and Year 1 shoreline monitoring 

 activities.............................................................................................................. 86 

Table 6.2 Low and high cost estimates over seven years for different scenarios 

 (note: totals are not discounted for time to present day dollars.) ......................... 87 

Table 7.1 General characteristics of sand ridges summarized from the data for the 

 Maryland shelf and for global sand ridges, including tidal sand ridges ............... 91 

Table 8.1 Data sets to be collected in the OCS sand dredging monitoring program.......... 104 
vii 

ACKNOWLEDGEMENTS 

 This report was prepared under contract to the Minerals Management Service, Contract 

No. 14-35-0001-31051. Barry Drucker was the MMS Project Manager and contributed 

significantly to the project objectives and the overall success of the project. Jacqueline Michel of 

Research Planning, Inc. (RPI) was the overall Project Manager and editor of the final report. 

The senior authors were Rob Nairn of W.F. Baird & Associates Ltd. and Jay Johnson and Dane 

Hardin of Applied Marine Sciences, Inc. (AMS). Miles O. Hayes of RPI contributed Section 7.1 

on the geology of sand ridges and shoals. Doug Scott and Derek Williamson of Baird contributed 

to the development of the Waves Protocol. Canadian Seabed Research Ltd. contributed to the 

Bathymetry Protocol. Robert Spies of AMS contributed to the biological protocols. 

 Woody Hobbs of the Virginia Institute of Marine Science (VIMS) was very helpful in 

coordinating the December 2000 workshop held at VIMS and providing access to the VIMS 

report on the sand resource sites offshore Delaware and Maryland. All of the participants at the 

workshop are acknowledged for their valuable input. 
1 

MONITORING PROTOCOLS FOR ENVIRONMENTALLY SOUND MANAGEMENT 

OF FEDERAL OFFSHORE BORROW AREAS ALONG THE U.S. EAST AND GULF OF 

MEXICO COASTS 

1.0 PROJECT INTRODUCTION 

 The Minerals Management Service (MMS) International Activities and Marine Minerals 

Division (INTERMAR) has the responsibility for administering the Department of the Interior’s 

role in mineral resource development other than oil, gas, and sulfur on the outer continental shelf 

(OCS). MMS does not develop and maintain a schedule of lease offering for OCS sand 

resources. Rather, the leasing process for OCS sand must begin by a request from potential users 

of the sand. Only recently have OCS sand resources been considered as feasible sources of sand 

for beach nourishment. Between 1995 and 2001, MMS conveyed 14,600,000 cubic yards of 

OCS sand for ten projects. 

MMS expects that OCS sand resources will be long-term sources of sand borrow material 

for coastal erosion management because of: 

• The general diminishing supply of onshore and nearshore sand; 

• Impact of sea level rise and other natural and human-induced factors leading to increased 

erosion; 

• The renourishment cycles for beaches or coastal areas requiring quantities of sand not 

currently available from State sources; and 

• Immediate/emergency repair of beaches and coastal damage from severe coastal storms. 

 In preparation for an increase in the demand for OCS sand, MMS has entered into 

cooperative agreements with nine states to identify and study potential OCS borrow sites. They 

have also funded baseline marine biological and physical oceanographic environmental studies at 

identified sites, as well as studies of the potential impacts of sand dredging, including modeling 

studies to determine the risk of shoreline erosion as a result of sand dredging. 

 To date, coastal erosion management projects utilizing Federal OCS sand resources have 

been examined on a case-by-case, project-specific basis. These resources must be managed on a 

long-term, large scale, system-wide basis to ensure that environmental damage will not occur as 

a result of continual and prolonged use. Sand sources that are to be used repeatedly may require 

additional biological and physical monitoring to ensure that unacceptable impacts to the marine 

and coastal environments do not occur. Therefore, MMS funded this current study to develop 

biological and physical monitoring templates for the Federal OCS sand resources. The project 

consists of the following components: 

• Development of field monitoring systems to evaluate the physical and biological impacts 

of using Federal offshore borrow areas on a long-term basis; 

• Examination of the feasibility, appropriateness, and desirability of putting these 

monitoring systems into place and identification of the need for collection of supplemental 

biological data or physical modeling information in the Federal borrow areas; 
2 

• Identification, review, and evaluation of environmental work or mechanisms 

(organizational, economic) that may be needed to offset any potential adverse impacts; 

and 

• Identification of the need for and collection of any additional geological/geo-physical data 

to define available sand supplies for planned projects within the study areas. 

 An additional component of the project is to formulate options and recommendations for 

including Federal, State, and local governments and other stake-holders in an overall planning 

process to manage the Federal offshore borrow sites in an environmentally responsible and costeffective manner over a long-term period. The results of that component of the project have 

been presented in a separate report (MMS 2001-090). 
3 

2.0 PROJECT OVERVIEW 

 The primary objectives of the project were to design a monitoring program that can be 

used to evaluate the potential physical and biological impacts resulting from the long-term use of 

OCS sand, and to prepare protocols for the monitoring plan elements. The focus is on long-term 

impacts because of the expectation that the borrow sites will be repeatedly dredged over time. 

The characteristics of the identified borrow sites have greatly influenced the overall monitoring 

plan design. Therefore Section 2.1 contains short summaries of these sites. As can be seen in 

these summaries, many of the sites are not connected to the nearshore sediment transport system, 

thus they will have patterns of recovery from dredging that may be different from nearshore sand 

habitats. 

 Figure 2.1 shows the project team and responsibilities of each team member. The project 

organization included a Quality Review Board that provided technical assistance to the project 

team and an independent internal review of the protocols report. Listed below are the 

qualifications and responsibilities of the three principal authors of the report. 

Jacqueline Michel, Ph.D. – Research Planning, Inc.: Project Manager/Geochemist 

• Over 20 years experience in the highly multi-disciplinary areas of oil spill planning, 

response, and natural resource damage assessment 

• Mapped most of the U.S. coastline as part of Environmental Sensitivity Index projects, 

including shoreline habitats, biological resources, and human-use resources 

• Prepared guidance documents and standard methods for field monitoring programs for 

Natural Resource Damage Assessments 

• Author of over 150 peer-reviewed papers, technical reports, and conference papers 

• Committee member of three National Academy of Science committees, two for the 

Ocean Studies Board, and one for the Marine Board 

• Author of the report on the Regional Management Strategy, Final Editor for all reports 

Robert B. Nairn, Ph.D., P.Eng. - Baird & Associates: Coastal Engineer/Planner 

• Developed an internationally recognized process-based longshore and cross-shore 

transport model for nearshore and foreshore areas 

• Extensive experience with analyzing sand transport rates and pathways, sediment 

budgets, and descriptive models for long term sea bed transport 

• Extensive experience in the testing and application of wave transformation models, 

• Has commissioned and interpreted geophysical surveys of sea bed conditions including: 

side scan, multi-beam, shallow seismic, air-borne LIDAR (SHOALS) in support of 

coastal process assessment investigations 

• Leading author of a section of the new USACE Coastal Engineering Manual chapter on 

cohesive sediment erosion/transport and deposition 

• Developed a method for quantifying impact of coastal engineering projects (including 

dredging) on fish habitat, identifying techniques and protocols to determine physical 

impacts that were then translated to impacts on productivity of biological communities 

through a large empirical database 

• Principal Author for the Sections on Physical Monitoring Protocols 
4 

Jacqueline Michel, Ph.D. 

 Research Planning, Inc. 

 • Project Manager 

 • Lead for Regional Management Strategy 

 • Editor for all reports 

 • Contributor to Monitoring Protocols 

QUALITY REVIEW BOARD 

Stan Riggs, Ph.D., Sedimentologist, 

 East Carolina University 

Pete Peterson, Ph.D., Benthic Ecologist, 

 University of North Carolina 

Al Hine, Ph.D., Shelf Sedimentologist, 

 University of South Florida 

Robert Dean, Ph.D., Coastal Engineer, 

 University of Florida

 • Participate in VIMS workshop 

 • Technical advisors to Project Team 

 • Technical review of draft Protocols report 

Rob Nairn, Ph.D., P. Eng. 

 Baird & Associates 

 • Principal author for Physical 

 Monitoring Protocols 

Miles O. Hayes, Ph.D. 

 Research Planning, Inc. 

 • Author for sand ridge geology 

 section 

Doug Scott, Ph.D., P.Eng 

Derek Williamson 

 Baird & Associates 

 • Contributors to Wave Protocol 

Jay Johnson, M.S. 

Dane Hardin, Ph.C.

 Applied Marine Sciences 

 • Principal authors for Biological 

 Monitoring Protocols 

Robert Spies, Ph.D. 

 Applied Marine Sciences 

 • Contributor to Biological 

 Monitoring Protocols 

Figure 2.1. Project organization chart and responsibilities. 
5 

Jay A. Johnson, M.S. Applied Marine Sciences, Inc.: Senior Oceanographer 

• Over 20 years experience as a biological oceanographer and marine ecologist dealing 

with complex scientific, regulatory and environmental issues involving sensitive legal 

and public issues 

• Has specialized in assessing the impacts of industrial activities, discharges and accidental 

releases to marine and estuarine environments 

• Has been involved in the design and implementation of multi-year marine monitoring 

programs at coastal power stations, municipal wastewater treatment plants, industrial 

dischargers and offshore oil and gas exploration and production facilities. 

• Experienced in assessing routine and catastrophic impacts to soft and hard bottom benthic 

communities as well as nekton and plankton communities in the intertidal, near shore, 

and deep offshore regions 

• Designed, managed and participated in environmental baseline and impact monitoring 

assessment programs in Alaska, the Gulf of Mexico, the U.S. West Coast as well as 

Russia, Kazakhstan the Middle East and Europe 

• Contributing author for development of international guidelines for oil and gas operations 

in fragile and sensitive environments 

• Principal Author for Sections on the Biological Monitoring Protocols 

Dane D. Hardin, Ph.C. Applied Marine Sciences, Inc.: Senior Marine Biologist 

• Over 25 years experience in the study of aquatic ecology 

• Specializes in the application of statistically sound sampling and analytical methods to 

the study of natural variations and anthropogenic influences on marine benthic 

communities 

• Has served as Program Manager and Principal Investigator on several studies funded by 

the US Department of the Interior Minerals Management Service investigating natural 

and human-induced variation in intertidal and subtidal communities in the Pacific and 

Gulf of Mexico Outer Continental Shelf regions 

• Has been actively involved in the Regional Monitoring Program for Trace Substances in 

San Francisco Bay (RMP) assisting in the design and execution of the water, sediment 

and bivalve bioaccumulation components 

• Has contributed to the design of photoquadrat sampling techniques, laser-aided 

quantitative sampling, and intertidal point-contact sampling methodologies. His 

contributions to laser-aided quantitative sampling have become the state-of-the-art 

technique in photographic sampling of benthic epifauna with remotely operated vehicles 

• Has 19 peer-reviewed publications in scientific journals and 100+ professional reports 

and presentations 

• Principal Author for Sections on the Biological Monitoring Protocols 
6 

 An important part of the project was a workshop held in December 2000 at the Virginia 

Institute of Marine Science. The objective of the workshop was to have scientific review of the 

proposed monitoring protocols before preparation of the draft report. The workshop was attended 

by representatives from the U.S. Army Corps of Engineers and many of the researchers funded by 

MMS on geological and oceanographic assessments of potential borrow sites, baseline 

environmental studies of these sites, monitoring studies of dredged sites, and assessments of the 

environmental impacts of dredging. Appendix A includes a summary of the workshop and a list 

of participants. Following the workshop, the project team carefully evaluated the comments and 

recommendations made by workshop attendees and discussed them with the MMS project COTR. 

The protocols included in this report reflect the input provided at that workshop. 

 The project results are presented in the following sections: 

 Section 2.1: Summarizes the available information on known OCS borrow sites. 

 Section 3: Describes the project approach, the questions that the monitoring program 

addresses, a summary of the direct and indirect impacts likely to occur from OCS sand dredging, 

and the rationale for the six monitoring elements selected. 

 Section 4: Includes the six Monitoring Protocols. They are formatted as stand-alone 

templates that include data collection and analysis methods, data specifications, and deliverables. 

It includes a section on Adaptive Management that is a key component of the monitoring design. 

 Section 5: Suggests the use of a review/advisory board to adapt the study designs based 

on the information obtained from on-going studies. 

 Section 6: Provides estimated ranges of costs for the monitoring elements. 

 Section 7: Identifies data gaps and summarizes the characteristics of ridge and shoal 

features, the primary type of sand borrow site identified to-date. 

 Section 8: Makes recommendations for management of data from the monitoring 

programs. 

 Section 9: Includes the references cited in the text and reviewed by the project team. 

2.1 Description of Borrow Sites 

A number of OCS borrow sites have been identified, many have been studied as part of 

Environmental Reports summarized in Section 3.1, and some have even been dredged to provide 

sand for beach nourishment projects. Figure 2.2 shows the approximate locations of the borrow 

sites that have been identified. 

This section provides a summary of the characteristics of the identified borrow sites to 

provide context for the understanding of possible impacts and the development of monitoring 

protocols. The following series of tables and figures present a summary of some key 
7 

characteristics of each of the identified borrow sites. It is important to note that the “estimated 

reserves” only present an approximate upper bound on the possible volume of sand available for 

beach nourishment projects. The reserves estimates have not accounted for a range of size 

limiting constraints including, but not limited to, presence of infrastructure and potential impacts 

of removing entire reserves. 

Figure 2.2. Locations of identified OCS borrow sites.

 

 Identified Borrow Deposit 

 

 Identified Borrow Deposit 
8 

Table 2.1. New Jersey OCS borrow sites (see Figure 2.3).

Location 

- 5 to 20 km offshore 

Description 

- 4 well-separated groups of sites 

Water Depth at Deposit 

- Less than 20 m deep 

Estimated Reserves 

- 113 million cubic yards 

Other Comments 

- May be shoal formations 

- Difficult to assess connectivity to 

coast using available data 

References 

- Louis Berger, MMS (1999) 

Figure 2.3. Deposits offshore of New Jersey. 
9 

Table 2.2. Maryland/Delaware OCS borrow sites (see Figure 2.4). 

Location 

- 10 to 16 km offshore 

Description 

- Three shoals all aligned NE/SW 

- Separated by 1 to 2 km wide channels 

Area Between Shore and Borrow Site 

- 15 to 20 m deep 

Water Depth at Deposit 

- 5 to 20 m deep 

Estimated Reserves 

- 422 million cubic yards 

Other Comments 

- Likely isolated from sediment transport paths (each other, coast or other areas) 

- May be influenced by processes within Delaware and Chesapeake Bays 

References 

- OCS Study 2000-055, Virginia Institute of Marine Sciences (2000) 

Location 

- 6 to 9 km offshore of Sandbridge, VA 

Figure 2.4. Bathymetry offshore of Northern Maryland showing three borrow sites. 
10 

Table 2.3. Virginia OCS borrow sites (see Figure 2.5).

Description 

- Oriented N/S (slightly sub-parallel to coast) 

Area Between Shore and Borrow Site 

- Substrate is silty sand 

- Approximately 14 m deep 

Water Depth at Deposit 

- 10 to 13 m deep 

Estimated Reserves 

- 40 million cubic yards 

Other Comments 

- Connectivity to the coast is suggested by depth and profile 

- Sediment type suggests that sites are not connected to the coast 

- May be influenced by processes within Chesapeake Bay 

References 

- Hardaway et al. (1998) 
11 

Figure 2.4. Bathymetry offshore of Southern Virginia. 

Figure 2.5. Bathymetry offshore of Southern Virginia. 
12 

Table 2.4. North Carolina OCS borrow sites (see Figure 2.6).

Location 

- 7 to 15 km offshore of Kitty Hawk 

- North of Oregon Inlet 

- Offshore Dare County 

Description 

- 4 sites 

Area Between Shore and Borrow Site 

- May be silt/clay 

Water Depth at Deposit 

- 15 to 25 m deep 

Estimated Reserves 

- 306 million cubic yards 

Other Comments 

- Not enough physical information to assess connectivity between each other and 

the coast 

- May be influenced by processes in Oregon Inlet 

References 

- Continental Shelf Associates (2000) 

- Boss and Hoffman (2001) Nag’s Head 

3 Mile Limit 

Figure 2.6. Perspective view showing inner shelf of proposed borrow deposits inshore and 

offshore of the three-mile limit, Dare County, NC. 
13 

Table 2.5. South Carolina OCS borrow sites (see Figure 2.7).

Location 

- Offshore south of Myrtle Beach (and others) 

Estimated Reserves 

- 560 000 cubic yards (offshore Myrtle Beach only) 

Other Comments 

- Straddles 3 mile limit 

- Biological studies by Van Dolah (1992; 1994) 

- Bury and Van Dolah (1995) 

Table 2.6. East Florida (see Figure 2.8).

Location 

- 13 km offshore of Jacksonville Beach 

- 11 km SE of St. John’s Inlet 

- Offshore Brevard, Indian River, St. Lucie and Martin Counties 

Water Depth at Deposit 

- Approximately 15 m – 20 m deep 

Other Comments 

- Completed pre- and post-dredging assessment of benthic fauna and sediment 

- For central Florida the Florida Geological Survey completed geophysical and 

vibracore investigations in cooperative work with MMS 

References 

- Lotspeich et al. (1997) 

- Freedenberg and Hoenstine (1999) 
14 

Figure 2.7. Analyses of records within three and five miles of erosional beaches that met certain criteria type sediment composition and sediment thickness, offshore South Carolina (Bury and Van Dolah, 199
15 

 

Figure 2.8. Possible Federal reserves offshore East-Central Florida 

(from Freedenberg and Hoenstine, 1999).
16 

Table 2.7. Alabama OCS borrow sites (see Figure 2.9). 

Location 

- 7 to 15 km offshore 

Description 

- Three potential resource areas 

Water Depth at Deposit 

- 12 to 20 m deep 

Estimated Reserves 

- 15.5 million cubic yards 

Other Comments 

- May be influenced by processes within Mobile Bay (central area is part of ebb 

shoal) 

- May be a bypassing shoal 

References 

- OCS Study MMS 99-0052, Aubrey Consulting (1999) 

Figure 2.9. Identified borrow sites offshore Alabama (from Aubrey Consulting, 1999).
17 

Table 2.8. Louisiana OCS borrow sites (see Figure 2.10). 

Location 

- 13 to 17 km offshore of Isles Dernieres 

Description 

- Single shoal 

Area Between Shore and Borrow Site 

- 8 to 10 m deep 

Water Depth at Deposit 

- Approximately 4 m deep 

Estimated Reserves 

- 1.6 billion cubic yards 

Other Comments 

- Probably not linked to coast by sediment transport pathway 

- Close to Terrebonne Bay 

References 

- Stone and Xu (1996), Stone (2000) 

%DWRQ5RXJH



3 mile limit

Figure 2.10. Location of the Ship Shoal deposit offshore Louisiana. 

 

2.2 Summary 

All identified OCS borrow sites share some common features. They are all in relatively shallow 

water, generally between 5 m and 15 m deep. The sites are mostly disconnected from coasts 

with respect to sediment transport paths. The sites also fall into three morphologic categories: 

isolated shoals/ridges, ebb shoals, and shelves. 
18 

3.0 PROJECT APPROACH 

 To have an effective and successful monitoring program design, it is essential that the 

program designers have a clear understanding of the ecological changes or effects to be 

monitored and the ultimate goal of the program, i.e., how are the monitoring program data or 

information going to be used. To accomplish this, the project team identified three key initial 

actions to the project: 

• In coordination with MMS/ INTERMAR project staff, identify the role of the OCS sand 

mining monitoring program in their management and environmental stewardship of this 

resource; 

• Review available literature to clearly identify the geophysical processes and biological 

ecosystems that would be affected by OCS sand mining for beach replenishment; and 

• Based on the information obtained from the two actions above, develop a series of broad 

scientific questions around which the monitoring program would be designed. 

3.1 Resource Management and Stewardship Goals 

3.1.1 Goals 

 Concurrent with the review of available literature, the project team developed a set of 

overall project goals around which the monitoring program would be designed. This effort was 

conducted with the assistance of MMS project personnel. These goals were to: 

1) Better understand the physical and ecological effects of sand dredging, and 

2) Obtain data or information relating to resource management decisions. 

3.1.2 Questions 

The resource management questions proposed by the team and MMS personnel were: 

• Is there a threshold above which continuous mining results in unacceptable 

damage/impairment to marine ecosystems? 

• Are there operational methods that can be changed to reduce/eliminate negative impacts 

to physical or biological conditions? 

• Does sand dredging result in predicted impacts? 

• Are there impacts that were not predicted or anticipated? 

• Do the predicted impacts occur and recover as expected? 

3.1.3 Assumptions 

During these initial team discussions with the MMS, it was determined that certain types 

of dredging (aggregate mining with open ocean sorting) and sensitive habitats would not be 

considered in the design of the monitoring program. Other "core design assumptions" to the 

program were: 
19 

• Only beach replenishment type mining would be considered. In this process only a small 

fraction of the material dredged is returned to the sea during dredging (less than 10 to 

20% of what is taken on board). Aggregate mining where the dredged material is graded 

offshore and only the desired grain size is retained would not be part of this project. In 

aggregate mining, the screening process results in a significant fraction of material taken 

on board that is returned to the sea during the dredging process. 

• Contaminated and cultural resource sites would be avoided as potential sand borrow 

locations. 

• Hard substrate areas (rocky reefs, coral reefs, artificial reefs, etc.) would be protected by 

both exclusion zones and buffer zones to prevent or avoid possible negative impacts, 

particularly those associated with the sedimentation footprint from the dredge plume. 

• Avoidable physical and biological impacts would be avoided. Therefore, critical 

habitat/locations and critical time periods would be avoided by implementing operational 

constraints to prevent these types of impacts. 

• The monitoring program would focus on only physical changes to habitat and community 

structure. Concerns about possible re-suspension of chemical contaminants would not be 

considered since all contaminated sites would be prohibited as possible sand borrow sites. 

3.2 Literature Review 

 To identify environmental parameters that need to be considered in the design of the 

long-term monitoring program for OCS sand mining sites, the project team reviewed the 

available literature. The literature review included pertinent technical papers on open ocean 

dredging and sand mining, environmental assessment reports, and biological baseline and 

monitoring studies of past dredging activities along the US coastlines and of potential OCS sand 

borrow sites. Most of these studies and reports were funded by MMS, for both the East and Gulf 

coasts of the United States as well as in the North Sea, where extensive offshore sand and gravel 

dredging is conducted. 

 In addition, studies conducted by the states of South Carolina and Florida were reviewed, 

and the project team also conducted independent literature searches to obtain information on 

offshore sand ridge ecology and dynamics. Section 9 provides a listing of the references 

reviewed by the project team. 

3.3 Ecological Issues of Concern 

Following the completion of the literature review, the project team identified those 

ecological resources (physical and biological) that would have the greatest potential for being 

affected by offshore sand mining, both directly and indirectly. Impacts occurring as a one-time 

dredging event at a given location or as repeated dredging of an area over some time period were 

included. All physical and biological processes were initially considered. 

 

Figure 3.1 shows the relationships between key physical and biological parameters that 

were identified during the literature review. The parameters are divided among one biological 

and three physical components, as well as geographic influences. In addition, Table 3.1 presents 
20 

the specific physical processes and biological communities potentially affected by OCS sand 

dredging, as identified during the literature review. 

Figure 3.1 Interactions between key physical and biological parameters for OCS sand mining. 

For the purposes of this project, impacts have been defined as follows: 

• Direct: Changes that occur as a primary response to the dredging process, without an 

intervening process (e.g., removal of infauna). They generally extend from the area of 

extraction to the edge of the plume sedimentation footprint and/or extent of the plume 

itself in the water column. 

• Indirect: Changes that occur as a result of a secondary response to dredging activities 

(e.g., change in fish populations because of the removal of infauna, changing the prey 

base), both within and outside the dredged area. 

The following sections discuss in greater detail the effects of sand dredging on the 

physical environment and processes and biological communities and processes. 

3.3.1 Geophysical Environment and Processes 

There are three primary components of the physical environment: 

• Morphodynamics. This group describes fluctuations and trends in changes to the 

elevation of the seabed and land surface extending from the vicinity of the borrow deposit 

to the furthest onshore extent of the dynamic beach zone. These changes are a result of 
Table 3.1. Summary of potential physical and biological effects of OCS sand mining for beach replenishment. 

Physical or Biological Change Effects/Impacts MorphodynamicsDirect Creation of depressions and furrows (possibly ≥ 0.3 meters) from 

removal of substrate 

Could result in changes to dredge site and shorPotential change to benthos 

Indirect Change to seabed topography beyond immediate dredge area through 

induced erosion/deposition (created by changes to sediment transport processes and pathways) 

Could result in impact (long-term) to shoreline unraveling of a shoal/ridge feature Potential change to benthos 

Change to sea bed mobility due to change in depth and in waves/currents (driving forces) 

No known or identified physical impacts. Potential change to benthos 

Change to shoreline evolution Altered shoreline dynamics 

Seabed CompositionDirect Removal (and disturbance) of substrate and exposure of underlying 

layer with different characteristics (grain size, DO, compaction and organic content). In some cases this may result in a positive impact where preferred substrates are exposed. 

No known or identified physical impacts. Potential change to benthos and indirectly to n

Change in grain size due to settling and deposition of sediment in overspill plume (inside and outside dredged area) 

No known or identified physical impacts. Potential change to benthos (smothering and al

Indirect Changes in grain size, compaction, organic content and DO induced 

by indirect erosion/deposition 

No known or identified physical impacts. Potential change to benthos and fish (altered h

Oceanography Direct Elevated levels of suspended inorganic and organic solids in the 

overspill and benthic plumes 

Temporarily increased water column turbidity Minimal effect to plankton, marine mammals, 

Indirect Changes to wave climate over and outside of the borrow area Could result in changes to shoreline geomorph

unraveling of a shoal/ridge feature Potential change to benthos 

Changes to shear stresses related to alterations to the wave climate No known or identified physical impacts. Changes to near bed current velocities associated with tidal, density driven and large scale circulation 

Could result in shoreline geomorphology impa

 21
Table 3.1. Cont. 

Geography (location of the borrow deposit)Direct None No known or identified physical impacts Indirect None No known or identified physical impacts PlanktonDirect Short-term Increased turbidity from cutter head or dredge barge 

overspill 

Limited reductions in primary and secondary p

Benthos

Loss or reduced suitability of habitat Total removal/loss of infauna and epifauna at b

recolonization by benthic organisms occurring longer) to a community with comparable pre-ddiversity and biomass but different species comstructure 

Direct (Soft Bottom) 

Changes in nearfield habitat condition resulting from altered sediment particle size composition from cutter-head discharge or altered ridge morphology 

Changes in community structure (species preseand biomass) in nearfield areas 

Direct (Hard Bottom) 

Increased deposition of advected suspended sediments, increased fluxes of suspended sediments during dredging 

Burial of near-bottom organisms, fouling of feesurfaces 

Indirect (Soft Bottom) 

Recolonization by an altered biological community Altered productivity and energy transfer effect

species composition of fish prey base 

Indirect (Hard Bottom) 

Recolonization by an altered biological community Altered productivity and energy transfer effect

species composition of fish prey base 

Nekton

Loss or reduced suitability of habitat Removal of infauna and epifauna: 1) Loss of f

spawning habitat; 3) Loss over overwintering h

Direct 

Increased turbidity and sedimentation Gill clogging and burial 

Indirect Recolonization by an altered benthic biological community Altered foraging efficiency with resultant effec

weight, and fecundity 

Marine Mammals & WildlifeDirect Collisions during dredging operations and some noise disorientation. Injury or death of animal; potential disorientat

Loss or reduced suitability of habitat Removal of infauna and epifauna: Change in f

Indirect Nearfield habitat changes Removal of infauna and epifauna: Change in fo Increased turbidity and sedimentation Reduced visibility resulting in reduced foragin

visual predators 

 22 
23 

sediment transport processes. These process and related changes may occur across a wide spatial 

scale, extending from individual sand grains, to bedform, to large-scale erosion and accretion, 

including shoreline change. 

• Seabed Characteristics. This group addresses the temporal and spatial (threedimensional) variability of the characteristics of the seabed including but not limited to 

grain-size distribution, dissolved oxygen, compaction, and organic content. There are 

interrelationships between morphodynamics and seabed characteristics as the movement 

of sediment results in disturbance and change to the bed conditions and the sediment and 

larval deposition environment of the seafloor. 

• Oceanographic Conditions. This group includes a wide range of processes and properties 

associated with the water column including waves, currents (with a wide range of forcing 

functions), suspended sediment levels, water temperature, salinity and others. 

 The most apparent direct physical impact is the removal of substrate and the reduction in 

the elevation of the seabed. This may result in the creation of furrows or a pit or the removal of a 

bathymetric high such as the top of a shoal. Indirect morphodynamic impacts include 

subsequent changes to the seabed topography, seabed mobility, and shoreline change. 

 From a purely physical perspective, the only change of consequence is the potential 

impact of dredging on shoreline change. For example, an increase in depth at a given location is 

not of direct importance to human activities – nor is a temporary sediment plume located in 

Federal waters some distance from shore. Theoretically the shoreline change can occur in one of 

two ways: 1) through alterations to the wave transformation pattern, changing the waves that 

reach the shore, in turn modifying the sand transport related processes and ultimately changing 

erosion and accretion patterns; and 2) by interrupting or modifying a sand supply pathway from 

or through the borrow area to the shore. A review of the currently identified OCS borrow 

deposits suggests that most of them are immune from the second impact because they are 

isolated from the sediment budget of the littoral system by large distances and muddy areas (the 

latter indicating the absence of a sand transport pathway). Nevertheless, this will not always be 

the case. Careful consideration must be given on a site-specific basis to the possibility of 

interrupting a sediment supply pathway to the shoreline. 

All other physical changes and impacts caused by dredging are important only if they 

result in a biological impact, either directly or indirectly. From a morphodynamic perspective, 

the direct impacts consist of the depressions, furrows, and pits left by the dredging operations. 

Clearly, these can have an important impact on the benthic community. The indirect biological 

impacts derived from a change to morphodynamics may include long-term changes to depths 

within and beyond the dredge area, changing the mobility of the sediment at a given location due 

to a change in depth and/or wave conditions at a given location. Probably the biggest concern is 

the potential for ridge and shoal type features to “unravel” or be smoothed out where borrow 

deposits are accessed on an ongoing basis. This outcome could lead to large-scale impacts to 

biological communities that rely on the structure of these features and to possible shoreline 

impacts. 
24 

Direct impacts to seabed characteristics include removal and disturbance of the substrate 

and exposure of an underlying layer with different characteristics (i.e., grain size, reduced 

dissolved oxygen levels, and compaction), and changes in grain size of surficial sediments due to 

settling of fines from overspill plumes or sediment reworking. Indirect impacts include changes 

related to erosion and deposition. These changes will only be significant where they result in 

biological impacts. 

The primary direct impact to the oceanographic conditions would be the elevated levels 

of suspended inorganic and organic solids in the overspill (at the point of discharge from the 

hopper dredge) and benthic (at the drag head) plumes. Indirect impacts include changes to the 

waves within and beyond the borrow area, changes to bed shear stresses and related seabed 

mobility due to changes to waves, and changes to near bed current velocities driven by tides, 

wind, and large-scale phenomenon. Recent UK studies as described by Newell et al. (1998) have 

found that the only detectable plume impact from a biological perspective is the direct 

sedimentation footprint and that this footprint is relatively limited in spatial extent (300 to 500 m 

from the borrow deposit). The investigations reported and referenced by Newell et al. (1998) 

pertain to heavily screened hopper dredge operations where there is a very significant overspill 

of sediment. Most sand dredging operations on the OCS will be non-screened (at least initially 

for beach nourishment borrow deposits) and the plume impact will be even less important than 

observed by Newell et al. (1998). 

3.3.2 Biological Ecosystems 

 For marine biota, the biological communities and associated habitats that were 

determined as being potentially affected by OCS sand dredging include: 

 

• Plankton 

• Soft substrate benthic communities 

• Hard substrate benthic communities 

• Nekton 

• Marine mammals and wildlife. 

As indicated in section 3.2, hard substrate areas will be avoided by dredging activities or 

be surrounded by sufficient buffer zones to prevent dredge discharges from having effects. In 

addition, since no sorting of dredged material will occur during beach replenishment dredging 

operations, the sediment plumes created by the dredge operations will be small and very 

temporary. Therefore, any effects to plankton should be minimal and of short duration 

(Hardaway et al., 1998; Hammer, 1993). 

Of the original five groups of marine organisms potentially affected by sand dredging 

activities in the OCS, only soft bottom benthos, nekton, and marine mammals and wildlife have 

any serious potential to be affected directly or indirectly. The principal impacts to soft bottom 

benthos result directly from removal of sand and entrained benthos. Other impacts may be due to 

increased turbidity during dredging, potential burial of the seafloor during dredging, and 
25 

long-term changes in sediment properties resulting from alterations in geophysical and 

oceanographic dynamics as discussed in section 3.3.1. 

Although short-term loss and changes in benthic community structure have been 

documented to occur following sand dredging (Blake et. al, 1996, Van Dolah et al., 1992), the 

ecological significance to the benthic community is uncertain. Studies investigating the recovery 

of benthic communities following dredging (Blake et. al., 1996; Newell et al, 1998; Van Dolah et 

al., 1992) have indicated that communities of comparable total abundance and diversity can be 

expected to re-colonize dredge sites within several years. However, even though these recolonized communities may be similar in terms of total abundance and species diversity, their 

taxonomic composition, in terms of dominant species and species abundance, is often very 

different from pre- to post-dredging. 

 

The key ecological question that remains to be answered is: Do the new benthic 

communities fill the same trophic function and provide the same energy transfer to higher trophic 

levels, as did the original communities? If they do not, then the potential long-term and 

cumulative ecological impacts of sand dredging may be far greater than predicted to date, a 

condition that may be unacceptable as more sites along the coast are dredged and others are 

dredged on a regular basis. 

The potential effects to fisheries from sand dredging are unknown, having been identified 

in most of the environmental impact assessments prepared for OCS sand dredging to be minimal 

or non-existent (Hammer, 1993; Louis Berger Group, 1999). This assessment was based on the 

determination that most of the fish inhabiting the potential dredge areas were characterized as 

wide-foraging or migratory, spending only part of their life cycle in the dredge borrow area. In 

addition, the ridge/shoal and shelf features identified as potential sand borrow areas are very 

large in geographic extent, extending over kilometers of seafloor and the potential borrow area 

for each dredging event is relatively small. Therefore the lost or altered habitat area, overall, 

would probably be minimal. 

The literature review effort conducted by the project team into the ecological utilization 

of ridge/shoal features by fish species indicated that little is known or has been published on the 

subject. Whether these features provide critical habitat for spawning, overwintering, or foraging 

area is relatively unknown. This information gap has been identified by the project team as an 

area requiring further study, and the results from such a study could result in the modification of 

the proposed monitoring program. 

Excluding the potential effects of lost essential habitat as a result of dredging, the greatest 

potential effect to the fish community utilizing a dredge borrow area is an alteration in trophic 

energy transfer from the benthos to the fish population. As indicated above, if the amount of 

energy being transferred to the fish population from the benthos is less than what is currently 

being provided by the area before dredging, then the potential long-term and cumulative 

ecological impacts of sand dredging may be far greater than predicted to date, a condition that 

may be unacceptable as more sites along the coast are dredged and others are dredged on a 

regular basis. 
26 

In consideration of marine mammals and other marine wildlife such as sea turtles and 

birds, of the identified direct and indirect impacts, the greatest potential for serious effect is 

associated with direct collision with the dredge vessel or entrainment in the suction dredge. 

3.4 Geophysical and Biological Parameters Addressed by the Monitoring Program 

3.4.1 Physical Monitoring Program 

Recognizing the fact that most physical impacts only have the potential to become 

significant when they result in a biological impact or affect the shoreline dynamics, the 

monitoring program must be developed to consider the biophysical interactions of impacts –

particularly the indirect type. The review of possible physical impacts points to the following 

focus for monitoring and modeling of physical parameters: 

• Changes to bathymetry; 

• Changes to waves and possible related shoreline changes; and 

• Changes to the seabed characteristics that may result in biological impacts. 

As discussed in Section 3.3.1, there are only two possible substantive physical impacts of 

concern: 1) those that result directly or indirectly in an unacceptable biological impact; and/or 2) 

those that lead to changes to the shoreline dynamics inshore of the borrow deposit. Four 

physical monitoring and modeling protocols have been developed to address these issues as 

listed below: 

1. Bathymetric and Substrate Surveys 

2. Sediment Sampling and Analysis 

3. Wave Monitoring and Modeling 

4. Shoreline Monitoring and Modeling 

The first two protocols primarily address the potential for biological impacts that may 

result from physical impacts. They essentially focus on tracking geomorphic changes to the 

borrow area and the surrounding sea bed. For many of the currently identified OCS deposits (see 

Section 2.1), the potential impacts to the form of ridge and shoal features will be closely 

monitored. The Bathymetric and Substrate Surveys Protocol also provides a description of the 

form of the borrow deposit (and any indirect changes on adjacent sea bed elevations) that is 

required as input to the Wave Modeling, the third protocol listed above. 

The third and fourth protocols listed above address the potential for shoreline impacts 

that may be directly related to changes to the sea bed elevations in the vicinity of the borrow 

deposit, in turn influencing the waves that reach the shore inshore of the borrow deposit, and in 

turn changing longshore and cross-shore sand transport rates and the resulting shoreline 

dynamics. Because there are many other factors that may result in changes to shoreline 

dynamics, the Wave and Shoreline Protocols include two key distinct features: 1) the need 

simply to document (or ensure documentation by others) of the waves (that cause changes to the 

shore) and shoreline change itself as a record of conditions; and 2) the need for modeling (in 

addition to monitoring) to attempt to isolate the direct influence of the changed bathymetry in 
27 

and around the borrow area on waves and shoreline dynamics (i.e. from all the other possible 

factors that may influence these processes). It is recognized that numerical modeling of these 

complex processes has many limitations, but nevertheless, these techniques provide at least some 

insight into the processes and the potential for dredging to lead to shoreline changes. Taken 

together with the field data derived from the monitoring and an understanding of the 

geomorphology of the area, the numerical model results provide the basis for evaluating the 

potential impacts of dredged borrow deposits on shoreline dynamics. 

A summary of the four physical monitoring protocols is presented in Table 3.2. This 

table provides the key potential impact, the objectives, the monitoring and modeling 

requirements and approximate cost of each of the protocols. This table is provided as an 

overview only and the information is insufficient to provide a guideline for the monitoring 

requirements. Please refer to the full description of the protocols in Section 4 for 

implementation. 

 Detailed monitoring of the plumes generated during dredging operations at the overspill 

point and the draghead has not been included as a requirement (or addressed with a protocol) 

owing to the fact that the primary concern is the extent of the sedimentation footprint, not the 

impact of the temporary plume itself. The extent of the sedimentation footprint will be 

documented by the sediment sampling program. A priori knowledge of the extent of the 

footprint would be useful to develop the spatial boundaries for the monitoring programs, and this 

is the focus of a Plume Model development and testing project currently being undertaken by 

Baird & Associates for MMS in FY02. 
Table 3.2. Summary of requirements of the physical monitoring protocols (NOTE: this table provided as an ov

 implementation refer to the full protocols in Section 4).

Requirements 

Protocol Potential Impact Objectives Monitoring Modeling 

Bathymetry and Substrate 

Changes to the morphology and substrate characteristics of the borrow deposit and surrounding area (particularly for ridges and shoals) and potential physical (waves and shoreline change) and biological impacts. 

1. Determine the location and 

quantity of sand removed and change to bathymetry caused by dredging operations. 

2. Quantify subsequent changes 

to bathymetry in the immediate vicinity of the borrow area. 

3. Quantify potential changes to 

the overall borrow deposit feature (e.g. ridge or shoal if one exists) 

1. Hydrographic Survey (single beam 

acoustic) plus Side Scan Sonar: or, 

2. Hydrographic Survey with Multibea

technique; or, 

3. LIDAR/SHOALS or other methods 

able to achieve specifications and requirements of the Protocol. 

Sediment Changes in sediment 

texture and total organic content and subsequent biological impacts. 

1. Define changes to texture 

caused by removal, sedimentation and indirect erosion/deposition processes. 

2. Potential changes may serve 

the assessment of changes to morphology of features at the borrow deposit (e.g. ridges and shoals). 

3. Determine changes in TOC 

to assess potential impact to benthic communities. 

Collect sand samples at the location of benthsamples and test for grain size distribution (bsieve and hydrometer test or equivalent) and method based on high temperature combusti

28 
Table 3.2. Cont. 

Requirements 

Protocol Potential Impact Objectives Monitoring Modeling 

Waves Change to wave 

transformation patterns over the dredged area with possible ultimate impact of shoreline change 

1. Develop a continuous 

record of wave conditions starting from first access of borrow deposit. 

2. Assess influence of initial 

changes to bathymetry. 

3. Assess influence of 

subsequent (direct and indirect) changes to bathymetry. 

Deepwater wave data through combination of measured directional data and nondirectional data and available hindcast data. 

Complete nearshwave transformamodeling to trandeepwater waves borrow deposit, oborrow deposit ashore (ultimately input to the shorechange model). 

Shoreline Shoreline erosion 

directly attributable to dredging at the borrow deposit. 

1. Document actual shoreline 

change (regardless of cause). 

2. Assess the impact of 

dredging at the borrow deposit. 

1. Beach and 

Nearshore Profile Surveys twice per year every 300 m. 

2. Georegistered 

aerial photographs and digitized shoreline twice per year. 

Apply GENESIS or equivalent to longshore sand trand related shorechange with and project prior to adredging comme(comparing to mchange in latter c

29
30 

3.4.2 Biological Monitoring Program 

The biological monitoring elements of the MMS OCS sand mining monitoring program 

focus on: 

• Benthic communities and their trophic relationships to fish, and 

• Marine mammal and wildlife interactions during dredging. 

 

Probably the most obvious biological effect of sand dredging operations is the complete 

removal of soft bottom habitat along with resident benthic organisms within the dredge area. 

Such removal affects not only the benthic communities, but also the fish assemblages that rely on 

the benthos for food. In addition, the potential small- and large-scale changes to seafloor 

geomorphology (e.g., substrate type and composition, surface texture, water circulation, nutrient 

distribution) due to altered wave patterns and sediment transport in the vicinity of the dredging 

operation may also affect benthic community structure and trophic energy flow. 

Therefore, the recommended approach for monitoring biological change involves 

measuring trophic energy transfer between the benthos and representative species of the fish 

population. This approach will facilitate the monitoring of changes over a very wide area of 

potential impact and changes resulting from the sand dredging operations regardless of the origin 

of the habitat change, e.g., direct removal of sand or potential changes in habitat sediment 

composition following geomorphological changes in the ridge and shoal or shelf structure 

resulting from the sand dredging. In addition to the measuring of trophic energy transfer effects, 

community structure and composition information should be gathered on the benthos as well as 

limited community structure and composition information on fish. 

In addition to monitoring trophic effects, it is suggested that the potential physical 

interactions and impacts to marine mammals and wildlife should also be monitored. This 

element of the monitoring program will be addressed as an operational control and monitoring 

component, that will occur during dredging operations. 

The recommended biological monitoring protocols have been designed with two 

principal objectives in mind: 1) the monitoring effort should be scientifically rigorous, and 2) 

the program costs should be affordable. Scientific rigor has been incorporated through several 

approaches. First, sampling sites are distributed among strata based on environmental variables 

known to influence communities to reduce within-treatment variation and improve statistical 

power. Second, we have specified a sampling design that utilizes statistical tests and interpretive 

criteria to minimize misidentification of dredging impacts. This design is amenable to 

comparisons of variation within and between treatments through analysis of variance (ANOVA). 

Using ANOVA, dredging effects will be ascribed to significant time x treatment interactions that 

coincide with a divergence between dredged and undredged areas at the time of dredging. 

Recovery will be ascribed to a reconvergence between dredged and undredged areas over time. 

Third, numbers of replicate samples are based upon the various characteristics of the biological 

communities to ensure representative abundance estimates and description of the communities. 
31 

The proposed biological monitoring protocols do not include components specifically 

designed to evaluate differences in dredging strategies (e.g., removal of sand in different spatial 

patterns that retain undisturbed patches to facilitate recovery). In particular, samples will not be 

distributed within strata according to dredged and undredged patches of seabed. To evaluate the 

effects of different spatial patterns of sand removal, the differences in benthic communities 

between dredged and undredged samples within a stratum will simply contribute to the withinstratum variation. The dredging pattern will provide an independent variable for use in general 

linear model procedures to determine what variables affect rate of recovery (see the Data 

Analysis and Synthesis section of the benthos and fishes monitoring protocol.) If retention of 

undredged patches increases recovery rates, the effect will be evident without the added expense 

of full replication and separate analysis for dredged and undredged samples within strata. 

Several aspects of the biological monitoring programs are assumed and will not be 

described in detail in subsequent sections. These include the use of precision navigation, such as 

differential GPS, to ensure that all samples are collected from the proper locations. Another is 

operational safety, such as wearing personal floatation devices at all times while working on the 

deck of the sampling vessel. 

Furthermore, it was determined that the biological monitoring program design would 

focus on: 

• Long-term rather than short-term impacts; and 

• Ridge and shoal type ecosystems, because of their greater micro-habitat and 

geomorphological complexity, and they represent the predominant morphology of the 

currently identified OCS sand borrow sites along the eastern seaboard of the U.S. 

However, it should be noted that the proposed protocols and monitoring program design 

is equally applicable to flat, shelf-type ecosystems.

A summary of the two biological monitoring protocols is presented in Table 3.3. This 

table provides the key potential impact, the objectives, the monitoring and analysis requirements 

and approximate cost of each of the protocols. This table is provided as an overview only and 

the information is insufficient to provide a guideline for the monitoring requirements. Please 

refer to the full description of the protocols in Section 4 for implementation. 
Table 3.3. Summary of requirements of the biological monitoring protocols (NOTE: this table is provided as an 

 implementation, refer to the full Protocols in Section 4) 

Requirements 

Protocol Potential Impact Objectives & Justifications Monitoring Analysis 

Benthos and Fishes; Trophic Transfer 

1. Total removal/loss 

of infauna and epifauna at borrow site with recolonization by benthic organisms occurring within 1-5 years (possibly longer) to a community with comparable pre-disturbance abundance, diversity and biomass but different species composition and community structure 

2. Altered foraging 

efficiency with resultant effects on individual size and weight. 

3. Altered species 

composition of fish prey base; altered productivity and energy transfer effects on the food chain 

• To determine the effects of 

dredging activities on benthic communities and the transfer of energy from benthic communities to fishes. While overall abundances of benthic organisms have been shown to return to pre-dredging levels in some cases within a year or two after dredging, species composition may be different and the ability of fishes to utilize such altered assemblages for prey is uncertain 

1. Collect 0.10 m2 benthic 

infauna samples from multiple strata at both impact and reference locations prior to dredging and in years 1, 3, 5 and 7 following dredging. 

2. Collect stomachs from 

numerically dominant or recreationally important species from multiple strata at both impact and reference locations prior to dredging and in years 1, 3,5 and 6 following dredging. 

1.a. Infauna taxonom

comparison with contents analysidetermining secproductivity val

1.b. Biomass measur

for determining secondary produvalues. 

1.c. Carbon and Nitr

stable isotope measurements obenthic prey spefish. 

2.a. Fish gut analysi

comparison with taxonomy.2.b. and nitrogen staisotope measurefish muscle tissu

32 
Table 3.3. Cont. 

Requirements

Protocol Potential Impact Objectives & Justifications Monitoring Analysis 

Marine Mammals & Wildlife 

Injury or death of animal; potential disorientation 

1. To obtain site-specific marine 

wildlife observation and behavior data during OCS dredging events. This information will assist state and federal regulatory agencies in assessing the appropriateness of imposed marine mammal and wildlife protection mitigation requirements and guide any necessary revisions of future mitigation requirements. 

2. To obtain and assess marine 

wildlife stranding data for potential relationships between stranded animals and animals observed during OCS dredging. This information will assist state and federal regulatory agencies in assessing whether there exist any obvious relationships between post-dredging marine wildlife strandings and the OCS dredging event 

3. To provide a means for 

implementing environmental mitigation requirements designed to minimize potential hazardous interactions with marine mammals and protected wildlife during dredging events. (This is the only "operational control" monitoring program element included in the OCS sand dredging protocols.) 

1. Collect observation and 

behavior data on marine mammals and wildlife during OCS dredging events. 

2. Collect marine mammal 

and wildlife stranding data for a 60-day period following dredging operations. 

3. Implement imposed 

environmental mitigation requirements designed to minimize collisions or harmful interactions between marine wildlife and dredging equipment. 

1. Compare observ

data with strandanimal data and document marinwildlife behaviodredging events

2. Compare marine 

data with observacollected during dredging event awith stranding darecorded for comtime periods duridredging years. 

33 
34 

4.0 MONITORING PROTOCOLS

 This section includes the monitoring protocols for the six elements that were identified in 

Section 3 as core components of the monitoring plan. They are formatted as stand-alone 

templates. The six protocols are: 

• Benthic Communities and Their Trophic Relationships to Fish 

• Marine Mammals and Wildlife 

• Sediment Sampling and Analysis 

• Wave Monitoring and Modeling 

• Bathymetric and Substrate Surveys 

• Shoreline Monitoring and Modeling 

 The three biological protocols have a more extensive introduction that describes some of 

the basic design considerations that apply to all of the biological protocols. 

4.1. Biological Protocol Approach 

The recommended biological monitoring approach emphasizes estimates of changes in 

the transfer of energy from benthic organisms to higher trophic levels, especially fish, resulting 

from dredging operations. It is recommended that benthic communities be sampled for organism 

densities. Fishes also should be sampled and numerically dominant and recreationally and 

commercially important species should receive additional investigation. These species should be 

analyzed for stomach contents to determine their utilization of benthic organisms. The utilized 

benthic species should be analyzed for their estimated secondary production using models that 

have developed over the past 20 years (Maslin, 1981; Morin, 1992; Tumbiolo, 1994). The 

amount of benthic production that is transferred to fishes should be estimated using accepted 

trophic transfer efficiencies. 

The sampling design involves collection of samples before and after each dredging 

operation over multiple dates in areas that were physically similar before dredging. Stratification 

is an important strategy for sample allocation that improves the ability to detect impacts. Strata 

are identified based upon factors that are known to affect the distribution and abundance of 

organisms in the target communities. Pre-dredging samples are collected from within strata (i.e., 

areas) that are as physically homogeneous as possible. Impacts and recovery are inferred by 

changes in biological similarity through time between dredged and control areas within strata. 

It is possible to design a monitoring program to detect a given amount of change in the 

parameter(s) being measured. Such an approach requires acceptance by the regulatory and 

scientific communities of a criterion for ecological significance. Once the maximum amount of 

acceptable change is established, the monitoring protocols can be designed to detect that amount 

of change, mainly through inclusion of sufficient numbers of replicates. When using this 

approach for designing a monitoring program, it is necessary to know the amount of variation in 

the parameters being measured, which requires site-specific data. Because we have neither 

consensus on appropriate levels of ecological significance nor site-specific data on trophic 

transfer, our approach for designing the biological monitoring protocols focus instead on 
35 

obtaining the most efficiently estimates of population means for measured parameters. This 

approach involves collecting the number of replicates that achieves the greatest decrease in 

standard error for measured parameters. 

Each of the following sections presents detailed monitoring guidelines for benthic 

communities and fish assemblages. In some cases, differences are required between baseline 

(i.e., before dredging) monitoring and monitoring that occurs after the dredging. These 

differences are discussed in the appropriate technical sections. 

4.2 Temporal Sampling Requirements 

 To effectively assess both the short-term and long-term changes in benthic community 

composition and trophic dynamics in the dredge borrow site and adjacent near-field areas, 

sampling will need to be conducted at varying intervals over several years. The first survey 

should be conducted shortly before dredging to describe pre-dredging conditions. Because initial 

successional processes may affect the rate and process of long-term recovery in dredged areas, 

the first post-dredging survey should be conducted one year following dredging, and surveys 

should be conducted every two years after that, until year seven. In addition to the pre-dredge 

survey, a baseline survey may also be required if sufficient data are not available for strata 

delineation. 

The purpose of the baseline survey would be to obtain sufficient information about the 

borrow site and adjacent areas to effectively delineate benthic habitats and associated benthic 

communities. This can be accomplished using Sediment Profile Imaging (SPI) equipment 

(VIMS, 2000) or benthic grabs. The effort can be combined with baseline geophysical data 

gathering efforts. At a typical ridge/shoal feature, this would include delineating the seaward 

flank of the feature, the landward flank and the ridge top, at a minimum, at both dredge and 

control locations. For a shelf feature, depth stratification may be more important. 

As far as possible, sampling should be conducted in the same season for both predredging and post-dredging sampling. Benthic communities exhibit strong seasonal patterns 

(Ott, 1977; Sarda, 1999; Vallet, 1999) and maintaining seasonal consistency of sampling reduces 

the effects of season on detection of long-term trends and recovery from dredging. It is 

suggested that summer is the best time to conduct sampling (Alden, 1997). Benthic sampling 

can be done concurrently with fish sampling or during a separate survey leg. 
Protocols For Benthos and Fishes: Trophic Transfer 

36 

1.0 OBJECTIVES AND JUSTIFICATION 

• To determine the effects of dredging activities on benthic communities and the transfer of energy 

from benthic communities to fishes. While overall abundances of benthic organisms have been 

shown to return to pre-dredging levels in some cases within a year or two after dredging, species 

composition may be different and the ability of fishes to utilize such altered assemblages for prey 

is uncertain. 

2.0 SAMPLING DESIGN 

2.1 Stratification 

Several factors are known to affect the distribution of benthic species and these should be 

considered in determining the pre-dredging strata. Sediment grain size and organic content are among the 

most important factors controlling the distribution of benthic organisms (Brown et al., 2000; Grove et al., 

1999; Mancinelli et al., 1998; McLachlan, 1996; Pearson et al., 1987; Rosenberg, 1995). These factors, 

which vary with depth, also can be affected by bottom topography and water motion (Tanaka and Dang, 

1996). The selection of strata for benthic sampling should be based on site-specific evaluations of these 

factors, as well as the morphology of the sand deposit to be dredged. Sand ridges, which form the 

dominant sand deposits along the East Coast, should be divided into strata of offshore ridge slope, ridge 

crest, nearshore ridge slope, and swale bottom, at a minimum. If the ridge is large enough or nearby 

seabed features are near enough and large enough to affect lengthwise heterogeneity in the sediment grain 

size and organic content, then additional strata should be designated. If sufficient data to designate strata 

are not available prior to the pre-dredging sampling, then additional sampling will be necessary to obtain 

these data. Although fish are more mobile than benthic organisms and may move between strata, they 

should be sampled within the same strata defined for the benthos. Maintaining consistent strata for 

benthic communities and fish assemblages will improve the ability to correlate benthic organisms with 

fish. 

To provide a balanced statistical design, defined strata should be present in both the dredged area 

and the control areas. The control area should be near the dredged area to ensure similarity of factors 

such as depth and wave regime, but removed far enough to minimize dredging effects. The ideal 

proximity between dredged and control areas will depend on site-specific conditions, such as depth and 

the amount of area being dredged. Delineation of strata and subsequent sampling should ensure the same 

sample density in both dredged and control areas. To satisfy this requirement, the areas of sampling strata 

in dredged and reference areas should be approximately equal. 

It is recognized that natural topographic and bathymetric variation may make it difficult to define 

identical strata at dredged and reference sites. The ability to detect changes caused by dredging may be 

reduced if there are large pre-dredging differences between dredged and reference sites. Delineation of 

strata is very important, so it must be done with care. The surest way to minimize the effects of natural 

variation between dredged and control sites is to employ the Beyond BACI design (Roberts, et al 1998; 

Underwood 1992), that uses multiple control sites to reduce the likelihood that differences in temporal 

patterns (e.g., changes that occur after dredging at the dredging site but not at the control site) are due to 

natural differences between sites. Unfortunately, a requirement for multiple reference sites would further 

complicate the potential difficulties of locating very similar dredging and control sites and also would 

substantially increase the cost of the monitoring program. It is suggested that the best solution to natural 

variation between dredging and control sites will include efforts to maximize similarity between them and 

then consider the remaining uncontrolled variation during data interpretation. 
Protocols For Benthos and Fishes: Trophic Transfer 

37 

After strata have been delineated, sampling locations should be randomly distributed within each 

stratum. Stratum boundaries should be established and sampling locations determined before beginning 

sampling. In the field, use of differential GPS will ensure that samples are collected in the correct 

locations. 

2.2 Sampler Selection 

2.2.1 Benthic Communities 

The selection of a sampler for benthic communities requires achieving a balance between 

consistent penetration and sample volume and ease of use. Important considerations are sediment texture, 

water depth, and sea state. Coarse or hard-packed sediments in deeper water may require a sampler that 

triggers on bottom contact to ensure deep enough penetration and prevent pre-tripping of the sampler 

during descent. Larger box corers, such as the USNEL corer (Somerfield and Clark, 1997), obtain 

consistent samples under most conditions, although they require heavy winches and large vessels for safe 

operation. Smaller box corers, such as the clamshell box corer (Diener et al., 1997), may be operated 

safely from smaller vessels. The Van Veen grab also satisfies the requirements of sample consistency and 

ease of use, and its many variations have been widely used (Dalto and Albuquerque, 2000; Kuehne and 

Rachor, 1996; Long and Lewis, 1987; McCabe et al., 1998; Muniz and Pires, 1999; Service, 1993; 

Southern California Coastal Water Research Project, 1977; Yi et al., 1988). While uniformity of samplers 

among all monitoring programs conducted under the auspices of MMS will enhance the comparability of 

results among regions, site-specific conditions may require the use of different samplers. 

Regardless of the benthic sampler selected, a uniform sampler area is necessary. Species richness 

and other community parameters have been shown to be area-dependent in a variety of environments 

(Boudouresque and Belsher, 1979; Eckmann, 1995; Pastor et al., 1996; Underwood and Skilleter, 1996; 

Watters, 1992; Weinberg, 1978). As the sampler area increases, the number of species collected 

increases. A sampler area of 0.1 m2

 is commonly used (Grove et al., 1999; Muniz et al., 1999; Rosenberg 

et al., 2000; Service, 1993) and should be employed in sand dredging monitoring. 

 The quality of benthic grab samples should be ensured by requiring each sample to satisfy a set of 

criteria concerning the depth of penetration and disturbance of the sediment within the grab. In this way, 

all samples will contain comparable volumes of sediment within the area of the grab jaws. Samples will 

be rejected for the following conditions: 

• A rock or shell fragment is wedged between the jaws of the grab allowing the sample to wash out. 

• The surface of the sample is significantly disturbed. 

• The sample is uneven from side to side, indicating that the grab was tilted when it penetrated the 

sediment. 

• The surface of the sample is in contact with the top doors of the grab, indicating over-penetration 

of the grab and possible loss of material around the doors. 

Weight can be added to the grab to improve penetration in harder-packed sediments and a shoe can be 

added to the bottom of the sampler’s frame to minimize over-penetration in softer sediments. 

2.2.2 Fish Assemblages 

A sampler for fishes and demersal invertebrates should be chosen from among types of trawls. 

Consistency of trawl type is even more important than consistency of benthic grabs because configuration 

differences can have large effects on the fishing characteristics and catching efficiency of the gear 
Protocols For Benthos and Fishes: Trophic Transfer 

38 

(Frecher, 2000; Halliday et al., 1999; Stokesbury et al., 1999). There are two main types of trawls, beam 

trawls and otter trawls. Within each type of trawl, there are numerous possible configurations involving 

differences in opening width, net mesh size, and net mesh configuration (i.e., diamond or square). Beam 

trawls have been commonly used to conduct fish population studies, as the beam insures that the width of 

the net remains constant, thus enabling calculations of population indices based on distance trawled. 

However, beam trawls are typically small in comparison with otter trawls, as the beam and thus the net 

opening are typically 3/4 of the width of the vessels transom. Otter trawls are more commonly utilized in 

fisheries investigations due to this limitation of beam trawls. The National Marine Fisheries Service 

(NMFS) uses otter trawls in its long-term fisheries survey of the eastern seaboard on North America, from 

Cape Hatteras, North Carolina, to Nova Scotia, Canada. This survey provides an index of abundance for 

numerous fish species, as well as other parameters such as scales, otoliths, and stomach content samples. 

Different types of otter trawls are used in this survey based on season and water depth. For spring and 

autumn inshore trawling, a 3/4 size #36 Yankee otter trawl is used. This net has a Horizontal Sweep 

(wingspread) of 8.6m and a Vertical Opening (headrope) of 1.4 m, and utilizes all steel doors. The cod 

end is lined with 1.3 cm stretch mesh to enable retention of juvenile and small fishes as well as large fish. 

The exact specifications of this net are on file at the NMFS Laboratory in Woods Hole, MA. 

In addition to consistency of sampling gear, consistency of trawling speed is also important. If 

trawling speed is too slow, fish in the trawl’s path may be able to escape. If trawl speed is too great, the 

gear may not stay on the bottom during the entire trawl. The optimum trawling speed is 3.5 knots, 

particularly if the 3/4 #36 Yankee trawl is used, as NMFS has determined this to be the optimum trawl 

speed for this net. The bottom of the doors and the footrope of the net should be observed after every 

trawl to check that they are being polished by contact with the bottom. Lack of polish indicates that the 

net was not riding on the bottom, thus allowing increased escapement of fish. There is no net that is 

100% efficient (i.e., there is no net that captures all of the fish in a towed area). Many fish are able to 

swim faster than the net is being towed, are able to avoid the net by swimming above it, are able to 

burrow into the sea floor, or are too small and are able to escape through the meshes of the net. For these 

reasons, it is crucial that the same type of net and vessels of similar length and horsepower are used 

throughout the monitoring effort, and, ideally, the same net and vessel would be used for the study’s 

duration. Use of sophisticated sonar and/or video equipment could be utilized to continually assess the 

net’s sampling ability, to document fish escapement and the species escaping, the exact dimensions of the 

net’s opening, and the length of each trawl. 

2.3 Sample Replication 

2.3.1 Benthic Communities 

The number of replicates to be collected from within each stratum should be determined from 

analysis of the benthic community made as part of the baseline or pre-impact survey. Several methods 

are available for determining the optimum number of sample replicates. One common method involves 

determining the statistical power provided by a given number of replicates (Sokal and Rohlf, 1995). As 

the number of replicates increases, the statistical power increases. The number of replicates may be 

determined by arbitrarily setting the amount of difference to be detected between sets of samples and 

solving the equation for the number of replicates. This approach can be used on data for species 

abundances or community parameters. The relationship between statistical power and number of 

replicates varies according to the variability in the data, which is species specific. This means that using 

this approach for determining the number of replicates requires choices to be made regarding which 

species should provide the benchmark. Instead, a method that integrates the entire benthic community by 

relying on the relationship between standard error and number of replicates is suggested. The standard 

error is an estimate of how much a mean estimated from a given number of replicates varies from the true 

population mean. If a larger number of samples is used to estimate the mean, then the estimate will more 
Protocols For Benthos and Fishes: Trophic Transfer 

39 

accurately reflect the true mean and the standard error will be smaller. Using this method, the number of 

samples can be specified to provide the most efficient reduction in standard error per number of samples. 

As replicates are added, a diminishing percentage reduction in the standard error is encountered in each 

successive replicate. A curve of the relationship between percentage reductions in standard error and 

number of replicates is shown in Figure 4.1. Proportionally smaller decreases are achieved with each 

additional replicate above 10, and it is suggested that this should be the minimum number analyzed from 

each stratum. Because this program will focus on measurements of benthic secondary production and 

trophic transfer to fishes, the metric that should be used for establishing the necessary number of 

replicates is total biomass. 

A separate sample should be collected from each stratum specifically for the analysis of stable 

isotopes. The handling and preservation of samples for stable isotope analysis differs from those required 

for analysis of benthic communities (Bosley and Wainright, 1999). One sample per stratum will provide 

information on the possible cause of any changes in stable isotope concentrations of fishes. 

Figure 4.1. Curve that indicates more than approximately 10 replicates would provide smaller 

 reductions in standard error for each additional replicate. 

2.3.2 Fish Assemblages 

The purpose of this monitoring program element is to assess the trophic transfer of energy to the 

resident fish population, rather than to assess changes in the resident fish community. The primary 

criterion for defining the adequacy of sampling for fishes is the collection of enough stomachs with prey 

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

20%

22%

24%

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

Number of Replicates
Protocols For Benthos and Fishes: Trophic Transfer 

40 

from the numerically dominant or commercially or recreationally important fish species to adequately 

describe their diets, in keeping with the focus on the effects of dredging on secondary production and 

trophic transfer to fishes. 

Determining the adequacy of replication will require some sample processing in the field. It is 

anticipated that a minimum of 30 stomachs with prey will need to be obtained to characterize the prey 

that each target fish species may be consuming, and more might be needed (Brown et al., 1992; Keats, 

1990; McKenna, 1991; Rachlin and Warkentine, 1988) if a rarefaction curve of cumulative prey items 

indicates that the assymptote is not approached. Moreover, prey selection varies with the age of the fish 

(Toepfer and Fleeger, 1995; Wyche et al., 1986), and sufficient stomachs to include the range of prey 

items are needed from each size class of a species to thoroughly describe how changes in benthic 

communities might affect trophic transfer to that species. Feeding activity of fishes may also vary 

between the day and night (Auster et al., 1995; Haight et al., 1993). Consequently, samples should be 

collected in both the day and night. A minimum of three day and three night trawls should be made in 

each stratum. Each trawl should be conducted along the long axis of the stratum, with beginning and 

ending points established to ensure that the trawl does not sample outside the stratum. Different locations 

should be used for successive trawls to minimize resampling the same area of seafloor. Trawls should be 

made following the collection of benthic samples to prevent trawl disturbances from biasing the benthic 

data. As trawls are being collected in the field, fishes should be examined to determine whether they 

have prey in their stomachs to ensure that sufficient samples are obtained for the gut-content analysis. 

2.4 Sample Processing 

2.4.1 Benthic Communities 

Initial processing of benthic samples should begin immediately when the samples are brought 

onboard the vessel. Initially, subsamples of sediment are removed for laboratory analysis of grain size 

and total organic carbon. Processing of benthic samples should follow traditional procedures (Swartz, 

1978). These involve sieving through 0.5-mm mesh screens, using filtered seawater to separate the 

organisms from the sediment. Organisms should be hand picked from the sieves using forceps and placed 

into jars that have been labeled according to project, site, coordinates, and date. Organisms should be 

narcotized by placing them into isotonic MgCl2 or propylene phenoxytol for several hours before they are 

preserved with buffered 10% formalin in seawater. After several days in formalin, the samples should be 

transferred to 75% ethanol. Rose bengal may be added at this time to facilitate sorting organisms from 

debris under dissecting microscopes. 

Consistent taxonomy is necessary to ensure that trends in benthic organisms are not confounded 

by differences in identifications. While identifying organisms to the lowest practical taxon is often 

performed in benthic studies, it requires much more effort without providing a concomitant increase in 

information compared to identifying organisms to higher taxonomic levels (e.g., family) (Clarke et al., 

1998; Clarke et al., 1999; Warwick et al., 1998). Identifications of fish gut contents should be made to a 

similar taxonomic level. 

Biomass measurements are necessary to estimate secondary production of benthic organisms. 

Blotted wet weight should be measured for each taxon (e.g., family). Because dry weight data are needed 

for calculation of secondary production, appropriate conversions factors should be applied to each taxon 

(Ricciardi and Bourget, 1998). Calculations of secondary productivity also require dry weight 

measurement for the largest individual of each taxon (see Section 3.1). For larger organisms, this can be 

estimated by converting wet weight to dry weight. For smaller organisms, this can be estimated by 

dividing the total wet weight by the number of individuals and applying an appropriate factor to account 

for differences in sizes of individuals. To facilitate identification of important prey species found in fish 
Protocols For Benthos and Fishes: Trophic Transfer 

41 

gut samples, identification of benthic taxa should be conducted concurrent with the fish gut analysis. In 

addition, benthic species should be separated into important prey groupings as determined during the fish 

gut analysis after the taxonomic identification work. 

The sample collected from each stratum for stable isotope analysis should be gently elutriated to 

remove the organisms from the sediment. An elutriation device that provides adjustable rates of flowthrough water and deposits organisms into submerged mesh bags is preferred. When sample elutriation is 

completed, the removed organisms should be placed into a container of ambient seawater for 

approximately 24 hours to allow purging of their gut contents. Care should be taken to ensure adequate 

oxygenation and temperature control so that the organisms do not die. After their guts have purged, the 

organisms can be separated into taxonomic groups and frozen in sample bags or jars. Once the samples 

are ashore, they should be freeze-dried to preserve them for analysis of stable isotopes, with care being 

taken to prevent sample contamination by oil from the vacuum pump. 

2.4.2 Fish Assemblages 

Processing of trawl samples begins when they are brought on deck. Fishes should be sorted into 

species, counted, measured for standard length, sex and sexual maturity determined and weighed. If very 

high numbers of a species are caught, random subsampling is acceptable for length and weight 

measurements. Following the initial separation of each trawl catch into species, and the selection of the 

numerically dominant and/or commercially/recreationally important, those species being analyzed for gut 

contents should be processed immediately to minimize continued degradation of the gut contents. A tally 

should be kept of the number of stomachs that appear to have prey in them. The three fish species that 

have been selected for analysis of gut contents and at least the next two most abundant or commercially 

or recreationally important species should be preserved in the field in buffered 10% formalin. Juvenile 

fishes may be especially valuable for analysis because their small size makes it more likely that 

differences in feeding strategies will be reflected in their stable isotope ratios. For large species, injection 

of formalin into the stomach (or removal and separate fixation of the stomach) may be required to ensure 

adequate preservation of gut contents. Preservation of more than the three most abundant species protects 

against loss of data if the most abundant species are not consistently collected in subsequent surveys. 

Muscle tissues for stable isotope analysis should be dissected from the fish using pre-cleaned 

stainless steel scalpels and a pre-cleaned teflon cutting board. Dissected muscle tissue should be wrapped 

in teflon sheets or aluminum foil, placed into sealable sample bags, and then frozen while on-board the 

survey vessel. As soon as possible, the tissue samples should be freeze-dried for storage and shipment to 

the analytical laboratory, again avoiding contamination with oil from the vacuum pump. Large samples 

are not necessary, but the analytical laboratory selected for analysis should be consulted as to the sample 

size required, and any other specific sampling requirements. Lipid removal may be considered to 

minimize the effects of reproduction on stable isotope concentrations. 

3.0 DATA ANALYSIS 

3.1 Benthic Community and Secondary Production Analysis 

The abundance of each benthic taxon should be determined by counting the number of 

individuals. The density and biomass of each taxon then can be extrapolated to m2

 and to the entire 

stratum by multiplying these numbers by the ratio between the sampler area and the total area of the 

stratum. Sediment grain size and total organic carbon samples should be analyzed to provide data for 

later use as independent variables in analysis of recovery processes and rates in benthic communities. 
Protocols For Benthos and Fishes: Trophic Transfer 

42 

Several investigators have proposed ways of estimating secondary production using static 

measurements (Brey, 1990; Tumbiolo et al., 1994). Biomass, temperature, and depth provide inputs for a 

recent method of estimating secondary production (Tumbiolo and Downing, 1994), according to the 

following equation: 

Log P = 0.24 + 0.96Log B - 0.21Log Wm + 0.03Ts - 0.16Log (Z+1) 

where P is annual productivity in grams dry weight/m2

, B is the average biomass in grams dry weight/m2, 

Wm is the maximum individual body mass in milligrams dry weight, Ts is the annual mean water 

temperature at the bottom in C°, and Z is bottom depth in meters. The secondary production for each 

stratum should be calculated by multiplying the production for each m2

 times the total area of the stratum. 

3.2 Fish Assemblage Biomass and Gut Content Analysis 

The abundance of each fish species should be determined by counting the number of individuals. 

The number and weight of each species then can be extrapolated to densities and biomass per m2

 and to 

the entire stratum by multiplying these numbers by the ratio between the sampled area and the total area 

of the stratum. 

In the laboratory, gut contents should be washed in freshwater and placed in jars with 70% isopropyl 

alcohol. Stomachs should then be emptied, the contents sieved with a 0.5-mm sieve, sorted, identified to 

the lowest practical taxonomic level, and counted. Percent volume, percent number, and percent 

frequency of occurrence of each type of prey item should be calculated for each fish species using means 

of all the stomachs from that species. These parameters can then be used then used to determine the 

Index of Relative Importance (IRI) (Pinkas et al., 1971). The IRI data should be normalized to percentage 

of the total IRI for a species, to enable comparisons based upon stomachs of varying fullness (Barry et al., 

1996; Carrasson et al., 1992; Cortes, 1997; Cortes et al., 1996). 

Consistent taxonomy of gut contents is necessary to ensure that trends in prey utilization are not 

confounded by differences in identifications. Prey items should be identified to the lowest practical 

taxon. Consistency of identifications will be affected not only by taxonomic expertise but also by the 

degree of digestion and the adequacy of preservation of gut contents. 

3.3 Stable Isotope Analysis 

Stable isotope ratios of organisms provide valuable clues to the carbon sources of their diets. 

Carbon stable isotope ratios change only slightly with transfer between trophic levels, so changes in 

primary producers that fix carbon could be detected. Nitrogen isotopes show larger changes with each 

trophic transfer, and they have been used to establish trophic level. 

Disturbed communities often host transitory or opportunistic species that may alter the dynamics 

of carbon and nitrogen flow to bottom-feeding fish or facilitate the transfer of an altered organic matter 

source term (Spies et. al., 1989). While detecting a population-level effect of a disturbed benthic 

invertebrate community on bottom-foraging fishes would likely require a large affected area and 

significant disturbance using standard methods of population assessment, stable isotope shifts might 

detect altered organic matter and energy transfer on less than a population level. Therefore, it may be 

possible to detect changes in the invertebrate prey of fish, post-dredging. 

Incorporating a carbon and nitrogen stable-isotope monitoring component into the long-term OCS 

sand mining monitoring program could provide the program with an additional source of data and 

perspective with which to understand what long-term ecological changes (if any) may be occurring. The 

data would be complimentary to the trophic energy transfer data. However, it should be understood that 
Protocols For Benthos and Fishes: Trophic Transfer 

43 

before incorporating any such measures into a long-term monitoring program, it would be appropriate to 

either carry out a pilot project on an existing sand mining area to see if such changes do occur or to 

carefully monitor the data from a long-term program and evaluate the results and contribution to the 

overall program on a regular basis. 

Measurements should be made of carbon and nitrogen isotopes in benthic species that constitute 

important prey items for fishes. Because stable isotopes from food items are incorporated into the bodies 

of consumers with only small changes, the isotopic signatures of consumers reflect the food they have 

consumed. This allows stable isotope data to be used to describe trophic pathways (Cabana and 

Rasmussen, 1996; Fry, 1999; Hansson et al., 1997; Keough et al., 1996; Peterson, 1999; Pinnegar and 

Polunin, 2000; Vander Zanden et al., 1999). These measurements should be made in pooled samples of 

specimens for important species from within each stratum for both dredged and control areas. 

As with benthic organisms, measurements should be made of carbon and nitrogen isotopes in 

important fish species. These measurements should be made in pooled samples of dorsal muscle for the 

selected species from within each stratum for both dredged and control areas. Because fishes can be very 

opportunistic in their prey selection (Derrick and Kennedy, 1997; Manderson et al., 1999), stable isotope 

measurements are an important adjunct to analysis of gut contents because they integrate more of the 

feeding history of the fish than does examination of the current contents of the gut. 

3.4 Data Synthesis and Analysis 

Data synthesis and statistical analysis should focus on describing the rate and process of recovery 

of dredged sites. Data synthesis should involve interpretation of data for benthic communities, fish 

assemblages, fish gut contents, and stable isotopes. Three hypothetical outcomes illustrate how the data 

from each component could be used. 

Outcome 1 

Species composition and organism densities within all strata of the dredged and control benthic 

assemblages become very similar five years following dredging. Nevertheless, biomass and estimated 

secondary production for key fish benthic prey species remain low and analysis of gut contents and stable 

isotopes suggest that fishes are feeding at a lower trophic level in the dredged area, compared to the 

control area. While the benthic communities appear to be recovered, dredging effects on fishes remain. 

Outcome 2 

Five years following dredging, the species composition in all strata of dredged and control areas remains 

very different, and gives no indication of converging. Nevertheless, overall organism densities and 

estimated secondary production of benthic communities have become similar at the dredged and control 

sites. Analysis of fish gut contents and stable isotopes suggest that utilization of benthic organisms for 

prey by fishes is the same at dredged and control sites. While benthic communities have not recovered, 

dredging effects on availability of benthic prey to fish assemblages are not apparent. 

Outcome 3 

Five years following dredging, the offshore ridge slope strata have become very similar between dredged 

and control areas in benthic community composition and secondary production. Nevertheless, benthic 

communities in ridge crest and shoreward ridge slope strata remain very different between dredged and 

control sites. It appears that the entire dredged area (i.e., all strata) has become physically and 

biologically homogeneous, similar to the pre-dredging offshore ridge slope. Perhaps because of fish 

mobility, there are no differences in either fish gut contents or stable isotopes between dredged and 

control sites, in any stratum. While the benthic communities exhibit only partial recovery, dredging 

effects on fish assemblages are not detectable. 
Protocols For Benthos and Fishes: Trophic Transfer 

44 

The endpoint for recovery should be established before post-dredging sampling. We suggest a 

return to the within-control 95% confidence interval for mean values at the dredged site. Metrics for 

determining recovery of the benthos might be species abundances, total biomass, and estimated secondary 

production. Consistent with the major objective of this protocol to determine the effects of sand dredging 

on trophic transfer from the benthos to fishes, we suggest biomass and secondary production should be 

emphasized. High within-strata variation at the control site will make it relatively easier to establish 

recovery. Because natural, non-dredging factors may cause control sites to change over time, 

determination of recovery should be based on comparisons between contemporaneous conditions at 

dredged and control areas. Rates of recovery can be estimated by computing the rates at which means 

from dredged and control areas converge. 

Step-wise multiple regressions also can be useful in these biological monitoring activities. Stepwise multiple regressions determine the significance of effects of several independent variables on 

dependent variables and allow estimation of the amount of variation in the dependent variable that is 

accounted for by the independent variables. In the case of sand mining, depth, water temperature, 

sediment grain size, total organic carbon, density of fishes, initial within-site similarities, and densities of 

early colonizers are examples of possible independent variables. Examples of dependent variables are 

rates of recovery or times to recovery. 

4.0 DATA SPECIFICATIONS 

• Include benthic species identified to a consistent taxonomic level (e.g., family) 

• Include benthic species abundances as both raw data and normalized to density per m2

• For benthic species include numbers of individuals and total biomass per taxon and total 

individuals, biomass, and number of taxa per sample 

• Include species identification, standard length, sexual maturity, and weight for each fish from 

each trawl 

• Include trawl area (i.e., width x length) for each trawl sample 

• Include volume, number of individuals for each taxon of fish prey, and percent fullness for each 

fish stomach 

• Include fish stomach content data reported for each trawl 

• Include benthic and fish stable isotope data for each sample or trawl 

• Include benthic and fish data reported separately for each stratum 

• Include geographic coordinates for each sample 

• Include time and date that sample was collected 

• Submit the information in digital (commercial spreadsheet format) and hard copy 

5.0 REFERENCES CITED FOR TROPHIC TRANSFER PROTOCOL 

Auster, P.J., R.J. Malatesta and S.C. Larosa. 1995. Patterns of microhabitat utilization by mobile 

 megafauna on the southern New England (USA) continental shelf and slope. Marine Ecology 

 Progress Series. Oldendorf 127: 77-85. 

Barry, J.P., M.M. Yoklavich, G.M. Cailliet, D.A. Ambrose and B.S. Antrim. 1996. Trophic ecology of the 

 dominant fishes in Elkhorn Slough, California, 1974-1980. Estuaries 19: 115-138. 

Bosley, K.L. and S.C. Wainright. 1999. Effects of preservatives and acidification on the stable isotope 

ratios (15N:14N, 13C:12C) of two species of marine animals. Canadian Journal of Fisheries and 

Aquatic Science. 56:2181-2185. 
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Protocols for Monitoring Marine Mammals and Wildlife 

48 

1.0 OBJECTIVE AND JUSTIFICATION 

• To obtain site-specific marine wildlife observation and behavior data during OCS dredging 

operations. This information will assist state and federal regulatory agencies in assessing the 

appropriateness of imposed marine mammal and wildlife protection mitigation requirements. 

• To obtain and assess marine wildlife stranding data for potential similarities between stranded 

animals and animals observed during OCS dredging operations. This information will assist state 

and federal regulatory agencies in assessing whether there exist any obvious relationships 

between post-dredging marine wildlife strandings and OCS dredging operations. 

• To provide a means for the implementation of environmental mitigation requirements imposed to 

prevent or reduce potential hazardous interactions with marine mammals and protected wildlife 

during dredging operations. (This is the only "operational control" monitoring program element 

included in the OCS sand dredging protocols.) 

2.0 SHIPBOARD PROTOCOL 

During shipboard dredging activities, marine wildlife observers should be placed aboard the 

dredge vessel or an ancillary craft to: 

• Observe for the presence of marine wildlife in the dredge area, 

• Document the behavior of marine wildlife to the dredging activities, and 

• Document any collisions or other negative interactions between the dredge vessel and support 

craft with marine wildlife. 

Prior to the commencement of any shipboard observations, a detailed observation plan should be 

prepared and approved by the local office of the National Marine Fisheries Service (NMFS) and the 

Minerals Management Service (MMS). This plan should identify the personnel who will be involved in 

the observation effort, the specific procedures and equipment that will be used to conduct the 

observations, the geographic location of the observations, the procedures for avoiding negative 

interactions between the dredging operation and marine wildlife, and how observations and stranding data 

will be analyzed and reported. The following are basic guidelines and protocols that should be followed 

in the drafting of a more project-specific observation plan. 

At least two trained marine wildlife observers need to be present aboard the dredge vessel 

watching for marine mammals, sea turtles, and other protected marine wildlife. Depending on the time of 

year, geographic location and total duration of the dredging operations (both hours per day and total 

days), four or more observers may be required. The observers should stand alternate watches to ensure 

that at least one or more observers is continuously watching for the presence and movement of marine 

wildlife during the dredging operations. It is critical that the observers position themselves aboard the 

dredging vessel at appropriate locations so they can observe the surrounding sea in all directions. Use of 

an ancillary vessel for conducting marine observations maybe preferable. To facilitate observations, each 

monitor should be equipped with conventional marine binoculars, range-finding binoculars, and nightvision binoculars. Use of mounted binoculars is encouraged, but their temporary mounting and safe use 

aboard the observation vessel should be discussed with the dredging contractor prior to commencement of 

field observations. 

Observations should be recorded on data sheets that include: 

• The date, vessel name and observer’s name, 
Protocols for Monitoring Marine Mammals and Wildlife 

49 

• The time and position of each sighting. (Positions can be obtained from the vessel’s Global 

Position System (GPS) or by a handheld GPS system, if the vessel’s system is not available to the 

monitor.), 

• The genus and species of each protected animal observed, along with the number of animals 

present and any associated wildlife, 

• The behavior (e.g., feeding, diving, slow travel) and unique markings of any animal(s) in each 

sighting (photographs of animals should also be made), 

• Photograph number for a particular sighting, and 

• Any suspected or observed adverse effects from the dredging operation, along with the steps the 

observer and the vessel took to avoid such impacts. 

Photographic and video equipment should be capable of clearly documenting animals at a 

distance of 200-300 meters. Although 35-mm SLR cameras equipped with telephoto lenses are the most 

commonly employed photodocumentation tool, use of digital video and still image equipment should be 

considered if resolution comparable to high quality 35-mm images can be obtained. 

3.0 COLLISIONS WITH MARINE MAMMALS AND WILDLIFE 

As indicated in the goals and objectives for the Marine Mammal and Wildlife Protocols, it is 

anticipated that permit or environmental mitigation requirements will be imposed on OCS dredging 

operations with the intent to prevent the collision or negative interaction with protected or sensitive 

marine mammals and wildlife (principally sea turtles). To this purpose, the project-specific marine 

mammal and wildlife observation plan should contain procedures for dealing with potential collisions or 

equipment interactions with marine wildlife. This plan should include project permit or environmental 

mitigation requirements for cessation of operations, agency notifications and emergency response for 

recovery and treatment of inured animals. 

At a minimum, the plan should consider the temporary cessation of dredging activities if an 

animal approaches the dredging vessel closer than 300-meters. If the vessel is underway and heading in 

the direction of the animal, a greater distance may be appropriate. If a collision or near-miss occurs 

between the dredging operations and a protected species, the on-site observer should record all pertinent 

information on the incident, and the animal affected and report immediately to the appropriate personnel 

at the regional NMFS and MMS offices. Photographs or video of the incident and animal should be 

collected, if possible. On-board marine wildlife observers should be used as third-party monitors to 

ensure the effective implementation of any imposed environmental mitigation requirements imposed to 

prevent collision or negative interactions with sensitive or protected marine wildlife species. 

4.0 POST-DREDGING STRANDING CENSUS 

Concurrent with the sand dredging operations and for a period of 60 days after completion of 

sand dredging, marine wildlife observers should be in communication with federal, state and local 

agencies responsible for documenting marine wildlife strandings. Every reported stranding that occurs 

along the coastline adjacent to the dredging operations should be checked for possible correlation with 

animals observed during the dredging operation (species, size, unique body markings, etc.) and for 

possible new markings on the body that would suggest a collision with the dredging equipment. 

5.0 DATA MANAGEMENT, ANALYSIS AND REPORTING 

Unless there has been a documented collision or impact between the dredging operation and 

marine wildlife, it is unlikely that the monitoring program will be able to clearly attribute a particular 
Protocols for Monitoring Marine Mammals and Wildlife 

50 

stranding to the dredging operation. Assessing stranding data for specific individuals that have been 

observed by the on-board observers in the stranding data may provide important anecdotal information. 

After multiple years of collecting field observation data during OCS dredging activities, and assessing 

stranding data for dredging and non-dredging years, the program should look for any trends that would 

indicate whether OCS sand dredging has a negative effect on marine wildlife. Repeated increased 

wildlife strandings following OCS dredging events for similar periods and seasons in non-dredging years 

could be indicative of some unobservable effect resulting from the dredging operation. 

Following the completion of a dredging operation and the elapse of the 60-day stranding period, a 

report should be prepared detailing the procedures employed for observing marine mammals and wildlife, 

details on all sighting and stranding data and any discussion of the data. All observation and stranding 

data should be provided in digital format for inclusion in the monitoring program database.
Protocols For Sediment Sampling and Analysis 

51 

1.0 OBJECTIVES AND JUSTIFICATION 

• To determine the change in sediment texture (as defined by a grain or particle size distribution) 

resulting from dredging within and adjacent to the borrow deposit. Changes may result from 

removal of sediment (within the area dredged), sedimentation within the zone of the 

sedimentation footprint that results from the fallout of the overspill and drag head plumes 

generated by the hopper dredge, and indirect impacts to erosion and deposition processes outside 

of the immediate dredge area. 

• The change in grain size is primarily important with respect to the possible impacts to benthic 

communities. 

• For borrow sites with distinct and active morphologic features (such as ridges and shoals) the 

baseline and future monitoring data derived from this protocol may also be useful for assessing 

and interpreting long-term changes to the form of the feature. 

• To determine the change in total organic carbon (TOC) content of sediment resulting from 

dredging within and adjacent to the borrow deposit. Changes will result from sediment removal 

(within the area dredged) and from sedimentation within the zone of the sedimentation footprint 

that results from fallout of the overspill and drag head plumes generated by the hopper dredge. 

• The change in TOC is primarily important with respect to the possible impacts to benthic 

communities. 

 Many of the requirements related to sampling are covered under the protocol for Benthos and 

Fishes as sediment samples will be collected as part of the benthic sampling program. Sediment samples 

will only be collected at locations where benthic samples are retrieved as changes to grain size are 

primarily “important” as they may relate to a biological impact. It is also noted that the Bathymetry and 

Substrate Protocol specifies surveys that will provide information from acoustic techniques related to the 

nature of the substrate in the vicinity of the planned borrow deposit. The information from this Sediment 

Sampling and Analysis Protocol provides ground-truth data for the more spatially comprehensive 

information collected under the Bathymetry and Substrate Protocol. 

2.0 SAMPLING LAYOUT 

 The sampling layout requirements of the Benthos and Fishes Protocol are applicable. Tests of 

grain size distribution and TOC should be completed for all benthic samples, including samples collected 

for benthic analysis and archiving. 

3.0 TEMPORAL SAMPLING REQUIREMENTS 

 The temporal sampling requirements of the benthic communities are applicable. 

4.0 METHODS AND SPECIFICATIONS 

 The sampling requirements of the benthic communities are applicable. 

 Sand-sized samples are usually analyzed with the use of stack of sieves ordered from largest wire 

cloth mesh on top to finest on the bottom with a pan at the base. The stack of sieves is shaken for 

approximately 15 minutes. The range of sieve openings must span the range of sediment sizes in the 

sample. A minimum of 6 full height or 13 half height sieves are required. A minimum sample size of 40 

g is required for each test. The analysis of silt and clay sized particles must be completed through a 

hydrometer analysis (see Das, 1998). 
Protocols For Sediment Sampling and Analysis 

52 

 All of the requirements of ASTM Standard D422-63 (Reapproved in 1990) on particle size 

analysis are applicable to this Protocol. The application of D422 requires sample preparation as described 

in ASTM Standard D421-85 (Reapproved 1993). The applicable ASTM reference is the 1994 version of 

Volume 4.08. All of the relevant requirements of this reference are applicable. 

 The TOC method should be based on high-temperature combustion. Inorganic carbon (e.g., 

carbonates) can be a substantial proportion of the total carbon in some samples, so treatment with acid is 

necessary to remove the inorganic carbon prior to TOC analysis (Plumb, 1981). 

5.0 DATA DELIVERABLES 

 The data grain size distribution for each sediment sample retrieved will be delivered as follows: 

• Plotting in semilog format 

• Include both grain size in both Phi and mm units 

• Include both Modified Wentworth Classification and Unified Soils Classification descriptions 

• Include geographic coordinates for each sample 

• Include time and date that sample was collected 

• Provide estimates of D10 (grain size where 10% by weight of the sample is finer) and D50 (also 

known as the median grain diameter) 

• Submit the information in digital (commercial spreadsheet format with both semilog plot and 

raw data) and hard copy 

The data on TOC content for each sediment sample retrieved will be delivered as follows: 

• Include both percent organic carbon and percent inorganic carbon 

• Include geographic coordinates for each sample 

• Include time and date that sample was collected 

• Submit the information in digital (commercial spreadsheet format) and hard copy 

Locations for all grain size and TOC samples shall be reported to both NAD27 and NAD83 horizontal 

datums (depths) and in UTM projection. 

6.0 REFERENCES FOR SEDIMENT SAMPLING AND ANALYSIS PROTOCOL 

American Society for Testing Materials. 1994. Volume 4.08, Soil and Rock (1): D420-D4914, American 

 Society for Testing Materials, Philadelphia, PA. 

Das, Braja M. 1998. Principles of Geotechnical Engineering, Fourth Edition. Boston, MA: PWS 

 Publishing Company. 712 pp. 

Plumb, R.H., Jr. 1981. Procedures of Handling and Chemical Analysis of Sediment and Water Samples. 

 U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS. 
Protocols for Wave Monitoring and Modeling 

53 

1.0 OBJECTIVES AND JUSTIFICATION 

• To develop a continuous record of the wave conditions that the borrow deposit (and areas 

inshore) is exposed to after the initial dredging operation. The data will provide the necessary 

information to evaluate any possible direct or indirect impacts of the dredging on the waves and 

associated physical and biological parameters. 

• To assess the influence of changes to bathymetry (due to the direct impact of dredging) on waves 

in the immediate vicinity of the borrow site, inshore of the borrow site, and in the adjacent 

nearshore zone. This information is required to determine whether there are any direct or indirect 

physical or biological impacts resulting from changes to the waves based on the modified 

bathymetry immediately following the dredging operation. 

• To assess the influence of possible subsequent changes to bathymetry (as an indirect impact of 

dredging) on waves in the immediate vicinity of the borrow site, inshore of the borrow site, and in 

the adjacent nearshore zone. In turn, any changes to the waves will be assessed with respect to 

resulting physical or biological impacts. 

2.0 DEEPWATER WAVE CLIMATE 

2.1 Temporal Requirements 

 It is essential that all borrow sites have a near continuous record of wave conditions at the site 

from the start of dredging operations (i.e. from the time the site is first dredged) to the cessation of the 

required long-term monitoring for the site (see Section 3.2 of this Protocol for a definition of the longterm requirements). In addition to this, there must also be wave data sufficient to define the long-term 

wave climate prior to any dredging. 

 The long-term wave climate considered during the permitting phase will consist of one year of 

recorded directional wave data plus one of the following: 

• An additional four years of directional wave data (for a total of five years) 

• A five-year record of non-directional wave data, which is used to validate the WIS wave hindcast 

(WIS data prior to 1976 should not be considered) for the site. The time period of the nondirectional data and the hindcast must correspond, and validation should be carried out based on 

summary statistics (e.g., wave height and period frequency by season) and time series. The error 

between WIS and the measured data must be such that it would not influence the assessment of 

potential impact to nearshore waves and shoreline dynamics (for the latter – see the Shoreline 

Monitoring and Modeling Protocol). If a hindcast other than the WIS hindcast is to be used, 

approval will be made on a case-by-case basis. 

2.2 Spatial Requirements 

 The spatial requirements for the wave climate pertain to the proximity of the wave data to the site 

under consideration. Where data from an active directional wave buoy at an upwave location are not 

available sufficiently close to the site to allow for a reliable transformation of these wave data to the 

borrow site location (i.e., using a wave transformation model), an instrument or device for determining 

directional waves must be deployed. The decision on whether a new instrument must be deployed will be 

determined on a case-by-case basis. It is recommended that during and after dredging, a directional buoy 

be located in very close proximity to the site (as close as possible to the site without risk to the 

instrumentation due to marine operations). 
Protocols for Wave Monitoring and Modeling 

54 

2.3 Instrumentation Guidelines 

 Directional wave measurement that is either required to be installed at the site, or may be 

considered acceptable if it is already in operation, must meet the following criteria: 

• Measurements made at an interval of less than 3 hours (preferably one or two hours) with a 

minimum sampling duration of 20 minutes; 

• Wave periods ranging from 4 to 20 seconds should be adequately resolved; 

• Directional spectra must be available in addition to the summary statistics that are typically 

reported (Hm0, peak period, mean wave direction, etc.). 

 It is recommended that a directional wave buoy be used for wave measurement. ADCP may be 

acceptable if it can be shown that the wave measurements are of similar or better accuracy obtained from 

wave buoys. Conventional single point “PUV” gauges are not recommended due to their inability to 

produce a full directional spectra and poor directional resolution in the presence of strong background 

currents. 

3.0 MODELING REQUIREMENTS 

3.1 Spatial Boundaries 

Offshore 

The offshore modeling is carried out to transform the measured wave climate to a location 

immediately offshore from the borrow site. Two factors may control the size of the offshore modeling 

region: 

• The distance from the nearest active directional wave buoy to a location in the vicinity of the 

borrow site; 

• The distance from a “deep water” location where the wave climate is defined to a location in the 

vicinity of the borrow site. In this case, “deep water” is defined as a depth greater than one half 

of the wavelength of a wave with the longest peak wave period present in the wave climate. 

In instances where a directional wave buoy is located very close to the site, the offshore modeling 

region may encompass a small area of perhaps a few miles or less. For instances where the buoy is 

located some distance from the site, or where waves from a more distant buoy must be transformed over a 

significant distance of transitional water depths, the offshore region may be very large. Modeling of the 

offshore region may also have to consider “backtransforming” waves measured at a buoy in intermediate 

water depths, to deep water, and then to the borrow region. “Backtransforming” waves is only acceptable 

where the buoy is located in water depths greater than 50 m and/or such procedures are appropriate given 

the bathymetry offshore of the buoy (i.e., the bathymetry is not overly complex). 

Borrow Region 

 The borrow region model domain addresses the area in the immediate vicinity of the borrow site 

and will encompass the full extent of a distinguishable sand body (e.g. a ridge or shoal) if one exists. The 

purpose of the borrow region modeling is to determine how changes to the bathymetry may influence the 

form of the sand body, if one exists, and to assess the change to the wave climate in the immediate 

vicinity of the borrow site, and particularly on the shoreward side of the feature. 
Protocols for Wave Monitoring and Modeling 

55 

Nearshore Region 

The nearshore region, which may vary greatly in size, encompasses the area from the nearshore 

side of the borrow site to the shoreline. The purpose of modeling this region is to assess how changes to 

the wave climate on the shoreward side of the borrow region will influence the wave conditions in the 

shoreline region, and ultimately shoreline change. 

 Depending on the site conditions, the selected model and the type of assessment being completed, 

the offshore region, borrow region and nearshore region models may be related in the following manners: 

• The borrow region model will derive its boundary from the offshore region model; 

• The nearshore region model will derive its boundary from the borrow region model. 

Alternatively, if the processes that must be modeled in different regions are similar, the regions may be 

modeled in the following manner: 

• All three regions may be simulated with the same grid resolution and model type; 

• The offshore region and the borrow region may be simulated with the same grid resolution and 

model type, and data from this model defines the nearshore model inputs; 

• The borrow region and the nearshore region may be simulated with the same grid resolution and 

model type, and are driven by data from the offshore model. 

Note that the requirement for the nearshore region’s offshore boundary to be defined by the results of the 

borrow region will likely require that the domain size of the borrow region model extend far beyond the 

limits of the borrow deposit itself. This makes it more practical to combine the borrow region and the 

nearshore region into the same model. 

 When defining the model boundary of the borrow region or nearshore region based on results 

from a model further offshore, it is often desirable to define a spatially varying boundary condition 

according to the output from the model providing the boundary, rather than making the assumption that 

the wave conditions are uniform along the boundary. This is very important when there is a large 

variation that occurs along the boundary in either wave height or direction, and may influence the choice 

of model that may be used due to this boundary requirement. 

 The alongshore extent of the nearshore (and borrow) region(s) must also be compatible with the 

alongshore extent of the shoreline change model (refer to the Shoreline Portocol). The wave 

transformation model provides the required boundary condition input to the shoreline change model. 

3.2 Temporal Modeling Requirements 

 Numerical model assessments of possible borrow region wave transformation impacts should be 

performed in the following cases: 

• Prior to initial dredging of the site in those cases where previous wave transformation modeling 

meeting the requirements of this Protocol has not been performed; 

• In the event that the sand body (where one exists) has been determined to have changed 

significantly based on a review of long term monitoring bathymetric survey comparisons. 

Numerical model assessments of possible nearshore wave transformation impacts should be performed in 

the following cases: 
Protocols for Wave Monitoring and Modeling 

56 

• Prior to initial dredging of the site in those cases where previous wave transformation modeling 

meeting the requirements of this Protocol has not been performed (either with respect to 

specifications of the model requirements or with respect to geographic coverage); 

• In the event that the sand body (where one exists) has been determined to have changed 

significantly based on a review of long term monitoring bathymetric surveys; 

• Prior to each new dredging operation, nearshore wave climate for the period dating back to the 

previous dredging operation shall be determined (so as to provide a continuous history of 

nearshore conditions). 

 Modeling requirements may be terminated once shoreline change monitoring is no longer 

required (see the Shoreline Protocol). 

4.0 MODEL SPECIFICATIONS 

4.1 Suggested Models and Applicability 

 There is a wide range of models (not to mention versions of individual models) available for 

wave transformation, and only a subset of these models will be applicable to the specific conditions at the 

borrow site of interest. This section specifies the processes and methods that must be considered and 

followed, as well as examples of the capabilities of several models that are currently available. Table 4.1 

specifies the processes that must be considered for the borrow region model, and for the offshore and 

nearshore model domains. 

 The primary additional factor that is recommended for consideration in the borrow region model 

is diffraction. However, in many locations it will not be necessary to consider diffraction effects. Tests 

were completed for the group of shoals offshore of the Maryland-Delaware border and it was determined 

that not considering diffraction resulted in changes of less than 10% to the wave heights compared along 

a line inshore of the shoals. The requirement to include shoaling and depth-induced breaking will depend 

on the local characteristics. It will be necessary to justify to MMS using physical process arguments that 

diffraction effects can be ignored, otherwise they must be considered. 

Table 4.1. Processes to be considered for various model domains. 

 Offshore Region Borrow Region Nearshore Region 

Shoaling unlikely possibly yes 

Refraction yes yes yes 

Depth-induced Breaking unlikely possibly yes 

Diffraction unlikely possibly possibly 

Bottom Friction unlikely no possibly 

Wind Generation yes* no yes 

Wave-wave Interactions possibly no no 

Reflection no no unlikely 

Current Interaction no possibly possibly 

Multi-Frequency yes

Multi-directional yes yes yes 

* - only if fetches in the model domain exceed 10 km. 
Protocols for Wave Monitoring and Modeling 

57 

The main distinction of the offshore model is the need to consider wind generation and possibly wavewave interaction, because the transformation distance from the nearest directional wave measurement 

station may be long. Shoaling and breaking need only be considered from the borrow deposit into the 

shoreline and then only if the borrow deposit is shallow and waves are required in or near the surfzone 

(the latter may not be the case if a package such as GENESIS is applied to address the shoreline impacts –

see the Shoreline Protocol). 

It is imperative that all regions that are modeled are done so with models capable of representing 

both the frequency spectrum (i.e. random waves) and directional spectrum (i.e., directional waves). For 

example, it is not acceptable to apply the unidirectional version of REF/DIF; instead, REF/DIF S must be 

applied. 

Tables 4.2 and 4.3 summarize the capabilities of models that are typically used for wave 

transformation. It is important to note that the capabilities summarized in these two tables are not 

definitive, and the capabilities of the models change with time and release of new version, thus the model 

developer’s recommendations will take precedence over these tables. Table 4.2 summarizes some of the 

more common spectral models, while Table 4.3 provides a list of functionality for phase resolving (i.e., 

Boussinesq or Mild Slope) models. It is evident from the tables that there is no ideal model for all 

situations and that in some cases it may not be possible to fulfill all the requirements at a given site. The 

purpose of Tables 4.1-4.3 is to assist in defining the best possible model for the particular application. 

Table 4.2. Capabilities of spectral wave transformation models. ♦ Indicates the process is included in 

the model. 

SWAN MIKE21 NSW STWAVE GHOST 

Shoaling ♦ ♦ ♦ ♦

Refraction ♦ ♦ ♦ ♦

Depth-induced Breaking ♦ ♦ ♦ ♦

Diffraction ♦

Bottom Friction ♦ ♦ ♦ ♦

Wind Generation ♦ ♦ ♦

Wave-wave Interactions ♦ ♦ ♦ ♦

Reflection 

Current Interaction ♦ ♦ ♦ ♦

Angular Limitations no yes yes some 

Multiple grids needed? usually not yes yes usually not 

Computational Speed fair fast fast fast 
Protocols for Wave Monitoring and Modeling 

58 

Table 4.3. Capabilities of phase-resolving wave transformation models. ♦ Indicates the process is 

included in the model. 

MIKE21 BW FUNWAVE REF/DIF S MIKE21 PMS 

Shoaling ♦ ♦ ♦ ♦

Refraction ♦ ♦ ♦ ♦

Depth-induced Breaking ♦ ♦ ♦ ♦

Diffraction ♦ ♦ ♦ ♦

Bottom Friction ♦ ♦ ♦

Wind Generation 

Wave-wave Interactions ♦ ♦ 

Reflection ♦ ♦ 

Current Interaction ♦ ♦ ♦ ♦

Angular limitations no no yes yes 

Multiple grids needed? no no yes yes 

Computational speed slow slow fair fair 

4.2 Modeling Methodology 

The following general guidelines are provided for applying the wave transformation models, but 

are not intended to replace the models’ user manuals and a thorough understanding of the model’s 

suitability for any given problem. 

4.2.1 Grid Specifications 

• Be aware of angle limitations. Most models require at least two or three different grids with 

different orientations to address a directional window of 60 to 90 degrees at the outer boundary of 

the model domain. Different versions of the same model may have different angle limitations so 

it is not possible to specify these limitations for each model here; 

• Some models (such as MIKE21 NSW) require grid cells that are much longer in the y-direction 

than the x-direction. For these models, the grid cell spacing will typically refer to the longest grid 

dimension; 

• Most of the phase-resolving models have grid-size limitations whereby a minimum of (for 

example) seven grid cells are required per wavelength. This can cause computation meshes to be 

extremely large, resulting in long simulation times; 

• The grid spacing must be sufficiently small to resolve the bathymetry of the area being dredged 

and important surrounding features. Justification for a selected grid spacing may be demonstrated 

by showing that halving the grid cell size (and defining elevations in the higher resolution mesh 

with the appropriate bathymetric data) results in essentially the same wave field. The contour 

lines from the plotted mesh should also clearly show the difference due to dredging; 

• For models with an x-y-θ grid (different computational direction bins), a directional spacing of 

not more than 5° to 6° should be used. There should also be enough directional bins such that the 

wave angle is not limited by the number of directional bins (instead the computational scheme 

will limit the permissible wave angles); 
Protocols for Wave Monitoring and Modeling 

59 

• For models that require user-defined frequencies to create a wave spectrum, a minimum of eight 

(and preferably more) logically selected frequencies should be used. 

4.2.2 Wave Climate Resolution 

 

Two techniques may be employed to create a nearshore wave history: 

A. The entire offshore time series may be transformed to the nearshore, with a simulation for each 

 time step; and 

B. A matrix of different heights, periods, and directions may be simulated and a transfer function 

 may be developed that will allow the measured range of wave conditions to be transformed to a 

 selected location for each transfer function. 

If method (B) is used, the following guidelines will apply: 

• If the location(s) of interest is outside the surf zone and breaking is not important throughout the 

model domain, then a simulation of a single wave height may be scaled to represent different 

wave heights; 

• To create a transfer function from a series of simulations, it is likely that 60 to 200 simulations 

will need to be carried out. This will depend on the possible range of direction and period, and 

whether or not multiple wave heights need to be simulated; 

• Directional spreading parameters for the various model simulations should be determined based 

on the measured wave data. It is often appropriate to use different directional spreading values 

for steeper (locally generated) versus less-steep (generated at a distance) waves. 

5.0 DATA SPECIFICATIONS 

5.1 Geo-referencing 

 All data locations, model grids and other spatial data must be defined in latitude and longitude 

using NAD 83 and NAD27 (both are required). In addition, it is also desirable to define these items in a 

projected coordinate system such as UTM. Associated metadata files should be completed in FGDC 

compliant formats. 

5.2 Data Formats 

 Data formats for input and output data must be clearly documented, and may consist of either 

ASCII or binary files. Subroutines for reading the data in either FORTRAN or C must also be provided. 

5.3 Wave Climate Summary 

 The offshore wave climate at the site (either in deep water or at the borrow location) should be 

provided in the form of frequency tables of height and period combinations in a digital file, and as hard 

copy in the report. Selected time series should be plotted for a number of the larger storm events. A 

digital time series of the summary statistics (height period and direction) should be provided in the format 

described above. If available, two-dimensional wave spectra should also be provided in a suitable digital 

format. 
Protocols for Wave Monitoring and Modeling 

60 

5.4 Model Input Data 

 Model input data and model version information should be provided so others can repeat the 

modeling exercise at a later date. Where possible the executable version of the model used should also be 

submitted (i.e., where the model is not proprietary). All model input data, including the bathymetric grid 

(geo-referenced), the input wave conditions, and any other model control parameters (numerical scheme 

options, winds etc.) should be supplied for each simulation. These data should be provided in digital 

format, as specified above. 

5.5 Model Output Data 

 Due to the possibly large amount of data generated in modeling tasks, the following output is 

required: 

• Plots of not less than 20 different wave simulations, showing contours of wave height and vectors 

indicating directions. Plots should include typical and more extreme wave conditions that are 

contained in the wave climate. Digital graphical formats are required in addition to hard copies; 

• The transfer function (if used) that transforms the waves from deep water to the study location; 

• A summary of the nearshore wave climate in the form of frequency tables for each of the 

scenarios simulated; and 

• A summary of the difference in the wave climate in the form of frequency tables for each of the 

scenarios simulated.
Protocols For Bathymetric and Substrate Surveys 

61 

1.0 OBJECTIVES AND JUSTIFICATION 

• To determine the location and quantity of sand removed and the associated change in bathymetry 

immediately after completion of dredging operations, thus providing a record of the short term 

and direct impact of the dredging project. 

• To quantify any subsequent changes to the bathymetry and substrate within the immediate 

vicinity of the borrow area to help in the assessment of biological impacts. 

• To quantify any subsequent changes to the bathymetry and substrate for the overall sand body 

feature or pit feature for those sites where such a feature is distinguishable (e.g. ridges and shoals 

or shallow pits). Long-term changes to the bathymetry could impact the distribution of benthic 

communities and also could impact shoreline erosion/accretion processes (by modifying wave 

refraction/diffraction processes). 

It is noted that the changes to substrate will be assessed through a consideration of the findings of the 

acoustic survey techniques specified in this protocol together with the grain-size distribution analysis for 

the samples specified in the Sediment Sampling and Analysis Protocol. 

2.0 SPATIAL BOUNDARIES REQUIREMENTS 

 The spatial extent of the survey will depend on the size of the borrow area and the local seabed 

conditions, including sediment type, seabed stability, current direction and speed, and the overall 

sensitivity of the area. 

 The area of the survey will be defined as the borrow area and a buffer zone around the dredged 

area. The survey area shall not be less than three times the borrow area for the specified dredging project. 

For example, the buffer zone around a 1 km2

 borrow area would be 370 meters and 520 meters for a 2 

km2

 borrow area. 

• Where the dredging takes place on a distinguishable ridge or shoal feature the survey will 

encompass the full extent of this feature, but not greater than 5 km2

. Where the area of the 

feature is larger than 5 km2

, the 5 km2 survey area will be centered on the dredge site. 

• Both pre- or post- dredge survey must be completed according to the applicable conditions. 

The area covered by long-term monitoring surveys following the post-dredge survey may be 

reduced or expanded in size. A reduction or expansion of the survey area will be dependent on the impact 

to the seafloor surrounding the dredged area. If there is significant impact, then the size of the survey 

area should be expanded. It may be determined that future surveys need only cover the borrow area. This 

should be evaluated on a case-by-case basis from survey to survey. 

3.0 TEMPORAL SAMPLING REQUIREMENTS 

 The following requirements must be achieved with respect to the timing of the surveys: 

• The pre-dredge survey will be completed no more than 30 days prior to the start of dredging. 

• The post-dredge survey should be completed immediately following the completion of dredging, 

and not more than 15 days after the completion of dredging. 

• One survey should be completed following a storm event with a two-year return period (See the 

Waves Protocol). 
Protocols For Bathymetric and Substrate Surveys 

62 

• Long-term monitoring surveys are required one, three, and seven years following the completion 

of dredging. The first year survey should be conducted in late spring early summer, coinciding as 

closely as possible with the timing of the benthic survey The clock for long-term monitoring 

survey requirements is reset for each new dredging operation. 

• If the impact on the seafloor is significant, then surveys should be conducted more frequently. 

• If there is minimal impact on the seafloor, surveys should be conducted less frequently. 

Repeated surveys at defined intervals will assist in the identification of the impacts and changes to the pit 

and surrounding areas, stability of the seabed, as well as changes in habitat. 

4.0 SURVEY REQUIREMENTS 

 With the exception of the drawing, plotting, line spacing and point density specifications, all 

requirements outlined under “Contract Payment Survey Classification 1” in EM1110-2-1003 (1994) and 

EC1130-2-210 (1998) of the US Army Corps of Engineers or the Technical and Engineering Guide for 

Hydrographic Surveying by ASCE (1998) should apply. Revised accuracy standards and related 

technical guidance contained in EC1130-2-210 supersede applicable portions of EM1110-2-1003. 

 Methodology for the measurement of tides and water levels are well documented by USACE 

(EM1110-2-1003, 1994) and NOAA (1999). Traditional tide staffs/tide gauges or RTK DGPS systems 

are all acceptable methods for measuring tides. Data from NOS (National Ocean Service) National Water 

Level Observation Network tide stations are also available. The recommended vertical datum for 

offshore coastal surveys is mean lower low water (MLLW). 

 General survey criteria for coastal dredge sites in water depths <30 meters are summarized in 

Table 4.4. There are three possible acceptable systems to meet the requirements of this protocol, that are 

described in the following paragraphs: 

• Single beam acoustic echosounding with side scan sonar 

• Multi-beam echosounding 

• LIDAR 

4.1 System Specifications 

 The survey system should be capable of: 

• Collecting bathymetry data to USACE specifications; 

• Assessing sediment transport features; 

• Assessing biological habitat. 

Survey system specifications, methods and limitations are described below. Table 4.5 provides a 

summary of single beam, multibeam, LIDAR and side scan sonar systems. 

4.1.1 Single Beam Echosounding 

 Single beam echosounding works on the principle of transmitting a pulse of sound, measuring the 

time for echoes to be received from the seafloor, and then converting the measured travel time into a 

corresponding depth. Travel time is converted to depth by multiplying the travel time by the speed of 

sound in water and then dividing the result by two in order to account for the round trip of the sound pulse 

in the water column. 
Protocols For Bathymetric and Substrate Surveys 

63 

NOTE: System resolution is not the same as vertical accuracy 

Table 4.4. Summarized general bathymetric survey criteria (water depth < 30 meters). 

 Type of Survey 

 All Systems Single Beam Multi-beam LIDAR 

Survey Positioning 

Horizontal Accuracy < 5 meters 

(95% Confidence Level) 

Horizontal Datum NAD 83 

Reference Grid System UTM (6 degree zones) 

Vertical Accuracy 0.06m (< 6m) / 0.15m (> 

6m) 

 

Vertical Datum MLLW 

System Resolution 1 cm (<100 m 

depth) 

1 cm 15 cm 

Speed and Coverage 

Vessel Speed 8 knots 10 knots 50 knots 

Survey Line Spacing 25m system/water 

 depth dependent 

Survey Cross Line 

Spacing 

 100m 

Survey Data Overlap n/a 10% minimum 10% 

minimum 

Quality Control 

Velocity profile > 2/day > 2/day n/a 

Bar calibration > 2/day 2/day n/a 

Max-beam angle 90-degrees n/a 

Beam overlap 10% minimum at least 10% 

Alignment calibration as required 

Patch test calibration periodic 

Performance Test 1/project 

Position Calibration 1/day 

Acoustic Frequency >= 200 kHz >= 200 kHz n/a 

Volume Computation 

Method 

dtm/dem 
Protocols For Bathymetric and Substrate Surveys 

64 

Table 4.5. Comparison of acceptable bathymetric survey systems. 

 Single Beam Side scan 

sonar 

Multibeam LIDAR (SHOALS) 

Recommended 

Frequency >= 200 kHz >= 100 kHz >= 200 kHz n/a 

Minimum 

depth 

range 

0.5 - 1 m below 

transducer 

1 - 3 m below 

transducer 

1 - 1.5 m 

Maximum 

depth 

range 

150-300m < 1000m 150-300m 

~50m but typically 

20 - 30m (2.5 x 

secchi depth) 

Survey speed 5-10 knots 4-6 knots 10-16 knots ~50 m/sec (50 knots) 

Areal survey 

coverage < 1 sq. km/hour 1 - 2 sq. 

km/hour 1 - 6 sq. km/hour 8 sq. km/hour 

Survey 

Platform vessel vessel vessel helicopter/aircraft 

Sounding 

Density 

1-3 meters along - track, 

across-track dependent 

on line spacing 

n/a 1-3 meters 3 - 15 m spacing 

Sounding Rate depth dependent (up to 

20/sec) n/a depth dependent 

(up to 25-30/sec) 200/sec 

Swath Width 0.05 to 0.14 x water 

depth 

variable (100m 

recommended) 

2 to 7.8 x water 

depth 

5-70% of altitude 

(100m) 

1cm System 

Resolution (water depth < 100m) ~10 cm 1-5cm +/- 15 cm 

 The basic single beam echosounder system consists of an acoustic transducer, a transmitter, and a 

receiver. The transmitter applies an electric current to the acoustic transducer, which converts this current 

into a pressure wave directed at the seafloor. When the pressure wave contacts the seafloor, it is reflected 

back to the acoustic transducer where the pressure is converted to an electric current and sent to the 

receiver. The output from the receiver is usually sent to a display device or recorder for visual 

recognition and logged digitally to a hydrographic survey software package. 

 The density of soundings with a single beam system is dependent on the survey line spacing, 

vessel speed and the echosounder ping rate. The footprint of the single beam transducer is dependent on 

the beam angle and the water depth. Essentially the single beam transducer calculates the water depth 

directly beneath the survey vessel. 

 The limitation of a single beam system compared to multibeam is the sample density or seafloor 

coverage. Advantages include survey costs and multibeam coverage of the seafloor is significantly 

reduced in shallow water (< 5 m). A high frequency (200 kHz or greater) transducer is required for single 

beam echosounding. 
Protocols For Bathymetric and Substrate Surveys 

65 

 Single beam systems are widely used for bathymetry surveys and in combination with a side scan 

sonar system. The combination of these two systems provides for 100% seabed coverage on the surficial 

sediments, sediment transport features, and the impact of dredging on the seafloor. 

4.1.2 Multibeam Echosounding 

 A multibeam echosounder works much like a single beam echosounder in that a pulse of sound is 

produced, reflected by the seafloor, and then received by an acoustic transducer. The main difference 

between the two systems is that the multibeam echosounder produces a number of separate beams 

(between 80-200 beams) forming a “fan” of acoustic energy in the water column. This fan of energy 

increases the swath, and therefore the coverage, of the multibeam survey as compared to the single-beam 

survey. Multibeam surveys can provide 100% coverage of a survey area. The location of the seafloor in a 

multibeam survey is computed by the angle and range measurements of the returning signals. The 

maximum vessel speed for this type of survey is higher than that of any other non-airborne survey at 10-

16 knots. 

 The relative density of a multibeam sonar is a complicated function of the ship's speed, sounder 

repetition rate, along-track beam width, across-track beam width, mode of sonar operation (equiangular or 

equidistant), and the ability to compensate for ship motion. 

 The main advantage of the multibeam system is the ability to collect 100% bathymetry coverage 

as well as backscatter data that can be used to characterize the surficial sediment and sediment transport 

features. Compared to a side scan sonar, a multibeam system generates quantitative bathymetric data but 

the backscatter data is usually lower resolution. The costs compared to single beam surveys are 

significantly higher and swath width is significantly reduced in water depths less than 10 m. However, 

the total cost of single beam survey together with side scan sonar can be comparable to the cost of 

multibeam survey. The required frequency for a multibeam system is 200 kHz or higher and must be 

capable of collecting backscatter/side scan data. 

4.1.3 LIDAR (Light Detection And Ranging) 

 LIDAR is a form of airborne hydrography that uses lasers to measure water depth. In the 1970's 

experimental laser based bathymetric profiling were developed in the U.S., Canada, Australia, and 

Sweden. Over time these have evolved into two primary systems; the SHOALS and HAWKEYE systems 

and the Australian LADS and LADS II systems. This system can either be attached to a fixed wing 

aircraft or a helicopter flying at an altitude of 200-1000 m, with a speed of 50-145 knots. The LIDAR 

system transmits two co-linear laser pulses, one infra-red and one green, towards the water surface where 

the infra-red beam is scattered at the water surface and the green beam penetrates the water and is 

scattered at the seafloor. The receiver onboard the survey aircraft detects returns from both beams and the 

time difference between the two is then used to calculate water depth. 

 LIDAR systems have a swath of approximately 100 m and can cover about 8-10 km2

 of survey 

area in one hour. The vertical accuracy of LIDAR can be as good as +/- 15 cm. 

 The swath width of the SHOALS LIDAR system ranges from 5 to 70% of the altitude and is on 

average 100 meters. The maximum penetration is 50 m water depth in ideal conditions but is typically 20 

to 30 meters and the sounding density can range from 3 to 15 m spacing. The maximum water depth limit 

is dependent on vegetation and the amount of suspended solids. 
Protocols For Bathymetric and Substrate Surveys 

66 

 The main advantage of the LIDAR system is that the areal coverage per unit time is much greater 

than acoustic systems. The sample density for the most part is less than multibeam sonars in equivalent 

water depths and significantly greater than single beam systems. The main disadvantages are 

mobilization costs and, unlike multibeam and side scan sonars LIDAR is less suitable for characterizing 

the surficial sediments and sediment transport features. A LIDAR survey would only be economical if 

monitoring surveys were required over a number of sites and/or if it can be mobilized by the Corps of 

Engineers at little or no cost. 

4.1.4 Side Scan Sonar 

 The basis of side scan sonar is that two acoustic transducers are turned on their sides in order to 

observe a series of echoes from the seafloor rather than just one echo from directly below the survey 

vessel. Side scan sonar uses a very narrow beam (0.1o-1.5o) to achieve a high-resolution image of the 

seafloor. This image is created by combining successive sonar scans as the system is towed through the 

water. In ideal conditions, the side scan sonar record can look like a photograph of the seafloor. 

The transducers in the side scan sonar system are contained in an assembly called the towfish. This 

towfish is towed behind the survey vessel at some depth below the sea surface in order to increase 

resolution and to limit noise effects cause by the vessel and the sea surface itself. A typical side scan 

sonar system will operate between 100-500 kHz with a variable swath, 50 to 100 meters swath is 

recommended for water depths 3 to 25 m. 

 Side scan sonar systems do not provide water depth measurements but they do provide 100% 

coverage of the seafloor and are ideal for mapping sediment types, sediment transport features, and 

bottom habitats. Where a single beam acoustic system is selected (i.e. in favor of Multi-Beam and 

LIDAR) it is required that a side scan sonar survey also be completed for the required Survey area. 

4.1.5 Horizontal Positioning 

Horizontal positioning requirements must meet USACE Class 1 guidelines of ± 5m for soft 

material. In general, code phase, meter level US Coast Guard differential GPS radio beacons or satellite 

based differential corrections (Starfix, Skyfix, etc.) will provide sufficient accuracy for most survey 

locations. This will also ensure the data is referenced to the NAD 83 horizontal datum. In offshore 

coastal areas carrier phase kinematic DGPS (either real-time kinematic (RTK) or post-processed) may be 

required to enhance the vertical accuracy of the soundings. RTK provides a horizontal and vertical 

solution for the vessel thereby eliminating the need for water level measurements. 

4.1.6 Motion Sensors 

Motion sensors are recommended for single beam surveys and required for multibeam surveys. 

Heave sensors that meet IHO standards are acceptable for single beam surveys. These sensors are easily 

calibrated and interfaced with single beam systems. Multibeam systems are much more complicated as 

the swath of soundings must be corrected for the full motion of the vessel. In the past, heave/pitch/roll 

sensors along with survey grade gyros have been deployed. The most accurate is an inertial navigation 

system that incorporates a combination of DGPS, motion sensor and gyro to correct for vessel motion. 

Extensive calibration tests are required to effectively interface these systems to multibeam sonars. 
Protocols For Bathymetric and Substrate Surveys 

67 

4.2 Survey Sounding Density Requirements 

Sounding density will relate to the type of equipment utilized for these surveys. The factors that 

influence sounding density of each system have been presented in the previous section. One of the 

following two sampling density requirements will apply to all hydrographic surveys: 

• For multibeam or LIDAR surveys, at least one sounding per 25 m2

. 

• For traditional single beam systems, survey lines will be spaced at 25 m intervals and cross lines 

will be completed every 100 m through the survey area. 

For comparison purposes USACE and IHO specifications for single and multibeam surveys are as 

follows: 

• The U.S. Army Corps of Engineers (USACE) recommends 100 ft or 30 m spaced longitudinal 

lines and 200 ft spacing on cross-sections for single beam Class 1 (Contract Payment) surveys 

(EC1130-2-210, 1998). For Class 1 multibeam surveys the USACE recommends a maximum 

beam angle of 90 to 120 degrees and 10 to 50% beam overlap. 

According to IHO (International Hydrographic Organization) minimum standards for Order 1 

hydrographic surveys the recommended maximum survey line spacing is 3 x average depth or 25 m, 

whichever is greater. This refers to the spacing of sounding lines for single beam echosounders, and 

distance between the outer limits of swaths for multibeam echosounder systems. 

5.0 FINAL CONSIDERATIONS 

Multibeam systems will provide high-resolution bathymetry maps of the seabed as well provide 

information on seabed sediment texture and bedform structures. The disadvantages associated with swath 

systems are their higher costs and the need to have highly skilled operators. In addition, the output often 

requires considerable post-processing time and expense to derive the best images. On the other hand 

single beam systems cost much less and are generally simple to operate. The main disadvantage of single 

beam echosounders is survey coverage. The lack of 100% coverage of the seafloor results in the need to 

undertake extensive spatial interpolation in order to provide full-coverage bathymetry maps of the seabed. 

A single beam echosounder in combination with a side scan sonar (as required under this protocol) will 

provide bathymetry as well as information of surficial sediment types and features. 

The primary focus of monitoring the borrow area is to calculate a reliable sediment budget and 

secondly to assess changes in surficial sediments, sediment transport and habitat. As a result, either a 

single beam echosounder/side scan sonar combination survey or high-resolution shallow water multibeam 

echosounder survey must be performed. The multibeam system must be capable of collecting highresolution backscatter/side scan data. The frequency of the single or multibeam transducer should be 200 

kHz or greater. If very fine changes to the overall sediment budget are to be measured then a multibeam 

system is required. A LIDAR survey is acceptable where sea conditions and cost considerations permit. 

6.0 DATA DELIVERABLES 

Minimum deliverables include the following: 

• Survey Operations Report and Hydrographic Sounding Chart of the area. 
Protocols For Bathymetric and Substrate Surveys 

68 

The survey operations report should include the following: 

- Description of the survey equipment as well as specifications 

- Field notes 

- Description of sounding system calibration 

- Description of positioning system and calibration 

- Methodology and equipment used to reduce soundings 

- Description of monuments/reference stations 

Sounding chart should include: 

- Survey location name or reference number 

- Name of survey agency and the date the survey was completed 

- Horizontal Datum and Projection used, NAD27 and NAD83 horizontal datum (both required) and 

UTM projection are required 

- UTM and geographic reference grids 

- Vertical datum used, as wells as the numbers and elevation values of all vertical control 

 monuments used for water level reduction 

- At least one reference station giving the latitude, longitude, northing, easting, and source 

- Key map and scale bar 

- List of survey equipment/software used 

- Source of shoreline, if applicable 

Required digital deliverables must include: 

- Navigation and sounding data (to both NAD27 and NAD83 horizontal datum and UTM 

projection) 

- Geo-referenced side scan sonar or backscatter images (to both NAD27 and NAD83 horizontal 

datum and UTM projection) 

- Interpreted surficial sediment and sediment features GIS data layers 

- Complete associated metadata in FGDC Content Standard for Digital Geospatial Metadata 

Additional deliverables could include: 

- Side scan sonar mosaic or backscatter map 

- Interpreted surficial sediment and features map 

- Digital data including navigation/sounding files, geo-referenced side scan sonar or backscatter 

 images, and meta-data 

Specific format of the digital data should meet USACE guidelines. 

7.0 REFERENCES FOR THE BATHYMETRIC AND SUBSTRATE SURVEYS PROTOCOL 

ASCE, American Society of Civil Engineers. 1998. Hydrographic Surveying, Technical Engineering and 

 Design Guides as Adapted from the US Army Corps of Engineers No 25. 

CHS, Canadian Hydrographic Service. 1998. Standards for Hydrographic Surveys, Second Edition. 

DETR, Department of the Environment, Transport and the Regions, 2001, Draft Marine Minerals 

 Guidance on the Extraction by Dredging of Sand, Gravel, and Other Minerals from the English 

 Seabed (Consultation paper), London. 
Protocols For Bathymetric and Substrate Surveys 

69 

Hughes Clarke, J.E; C. deMoustier, L. Mayer, and D. Wells. 2000. Y2K Coastal Multibeam Sonar 

 Training Course Lecture Notes, Vols. 1 & 2, Burlington, Ontario. 

Hughes Clarke, J.E. 1999. Provisional Swath Sonar Survey Specifications, National Topographic and 

 Hydrographic Authority, Land Information New Zealand, TH Technical Report #2. 

ICES, International Council for the Exploration of the Sea. 2000. Report of the Working Group on the 

 Effects of Extraction of Marine Sediments on the Marine Ecosystem, Gdansk, Poland. 

IHO, International Hydrographic Organization. 1997. Standards for Hydrographic Surveys, Special 

 Publication #44, 4th Edition, Draft after 2nd meeting of S-44 WG. 

Miller, J., J.E. Hughes Clarke, and J. Patterson. 1997. How effectively have you covered your 

 bottom?: Hydrographic Journal 83:3-10. 

NOAA, National Oceanic and Atmospheric Administration, April 23, 1999. NOS Hydrographic Surveys 

 Specifications and Deliverables. 

USACE, United States Army Corps of Engineers. 1994. Engineering and Design, Hydrographic 

 Surveying, EM1110-2-1003. 

USACE, United States Army Corps of Engineers. 1998. Project Operations, Hydrographic Surveying, 

 EC1130-2-210. 
Protocols for Shoreline Monitoring and Modeling 

70 

1.0 OBJECTIVES AND JUSTIFICATION 

• To document the change to the shoreline inshore of the borrow deposit during the period of active 

use of the deposit and thereafter until it is determined that there has been no significant impact. 

This objective is addressed through monitoring the shoreline, nearshore profiles, and nearshore 

bathymetry. By extracting sand from the sea bed, it is possible that the waves passing over the 

dredged area will be modified leading to possible changes in longshore and cross-shore sand 

transport patterns, and therefore, shoreline and nearshore morphodynamics. All shorelines and 

nearshore zones are dynamic, the purpose here is to determine whether these dynamics have been 

significantly altered by the dredging activities (and subsequent indirect impacts of dredging). 

• To assess the role of changes to wave transformation patterns over the borrow deposit on 

shoreline change and nearshore morphodynamics. This second objective requires the application 

of numerical models to assess whether there has been or will be any impact of changes to 

bathymetry at the borrow site on the sand transport and morphodynamic processes in the 

nearshore zone and at the shore. 

It is recognized that both shoreline monitoring and shoreline modeling also fall under the 

jurisdiction and mandate of other agencies. For example, shoreline monitoring programs are usually 

administered by agencies within each State as part of a Coastal Zone Management Program. Shoreline 

modeling may also be completed by the State or at least by the proponents or sponsors of coastal projects 

(such as the Corps of Engineers District offices) that require sand from the borrow deposits under MMS 

jurisdiction. Therefore, it is necessary that this Protocol be applied in a manner that is consistent with 

these activities by others and in such a way to avoid duplication of effort. 

2.0 MONITORING AND MODELING 

 Shoreline monitoring is performed in most States through a combination of profile surveys 

repeated at some frequency (e.g. twice a year, once a year or once every two or more years) in addition to 

the use of aerial photos to document shoreline change (or the change of some other related distinguishable 

feature such as a vegetation line). The purpose of the shoreline monitoring is to document change or lack 

thereof. Another key piece of information to assess shoreline change is the deepwater and nearshore 

wave climate (both prior to and after the initial use of a borrow site) – see the Waves Protocol. 

Documentation of the shoreline change and the driving forces for change in the form of the wave climate 

on their own are not sufficient to provide an explanation for observed changes and to discern whether 

these changes may be attributable to dredging at an offshore borrow site. The reason for this is that the 

wave climate (and the associated sand transport and shoreline change) for one year or even a period of 

several years is not stationary or well represented by an average set of conditions. Furthermore, the 

influence of other external factors that affect shoreline change such as the impact of coastal structures, 

beach nourishment projects, other impacts to sand supply or sea level rise are not stationary with time (i.e. 

they also vary from period to period). 

 Therefore, in order to determine the influence of one factor independent of the variation of other 

factors it is necessary that modeling be performed. Modeling provides a means of creating a common 

basis for comparison. For example, shoreline change for a five-year period after a dredging project could 

be simulated using wave models coupled to shoreline change models with measured wave data as input. 

The simulation could be calibrated and verified against documented shoreline change for that period. 

Then the model could be run again with the original bathymetry prior to the dredging project to determine 

whether any changes were directly attributable to direct and indirect impacts of dredging on the borrow 

deposit. This same approach should be (and in many cases has been) undertaken prior to the initiation of 

dredging on a borrow deposit. However, often there is insufficient local wave data or reliable and 

sufficiently accurate shoreline change data to complete this assessment in a pre-project “hindcast” mode. 
Protocols for Shoreline Monitoring and Modeling 

71 

 Furthermore, completing this assessment after the fact provides a different perspective and an 

additional test of the model predictions. In the pre-project assessment the shoreline change without the 

dredging project is known, whereas in the monitoring assessment (after the initial dredging event) the 

shoreline change with the project is known. 

 It is worth mentioning that there are different views on meaningfulness of shoreline change 

modeling in the literature. It is important to recognize that the recommendation to perform modeling as 

part of this protocol is related to the possible changes nearshore wave conditions related to changes to 

distinct offshore features such as shoals or ridges. Numerical models of wave transformation have been 

shown to accurately reproduce measurements from physical models in laboratory experiments and from 

full scale measurements. It would be impossible to assess such complex changes without the application 

of numerical model. 

There are two possible contributing factors to shoreline change associated with dredging of 

deposits in Federal waters: 

1. Changes to nearshore wave conditions, longshore sand transport and therefore shoreline change; 

and 

2. Interruption or cut off of pathways of sand to shore (where they may exist). 

Methods for determination of deepwater and nearshore wave conditions and the influence of a 

dredging project on the latter are specified in the Waves Protocol. The focus of this Shoreline Protocol is: 

• The collection of the necessary information to document shoreline change, and 

• The specification of methods to simulate shoreline change with models. 

The remainder of this document will address the requirements of both monitoring and modeling necessary 

to discern the role of dredging projects in Federal waters on shoreline change, if any. 

3.0 SPATIAL BOUNDARIES 

3.1 Monitoring 

In most States the monitoring program covers the entire length of the open coast. This is the 

preferred spatial coverage. 

 Basco et al. (1999) determined that the area of measurable impact to waves that reach the 

shoreline in response to a hypothetical removal of a large part of the Sandbridge shoal offshore Virginia 

was at least three times the lateral extent of the borrow area. Impacts to shoreline change will extend well 

beyond the immediate area of impact to waves and sand transport (just as impacts of inlet structures 

extend many times the length of the structure in the downdrift direction). 

 Therefore, in those States where monitoring is not being performed along the entire coast, for the 

purposes of assessing the impact of dredging in Federal waters, the area of monitoring must extend: 

• A total of five times the shoreline projected alongshore extent of the borrow area (including all 

past borrow areas in the same vicinity) in both the updrift and downdrift direction for a total 

length of monitored shoreline of ten times the shoreline projected alongshore extent of the 

borrow deposit(s). 
Protocols for Shoreline Monitoring and Modeling 

72 

The spatial coverage of the required shoreline monitoring should be reassessed and expanded or 

reduced depending on the findings of the monitoring and modeling. 

3.2 Modeling and Analysis 

As noted in Section 2, for the shoreline change assessment it will be necessary to have an 

adequate record of deepwater waves for the monitoring period and to transfer these waves inshore using 

wave transformation models. The requirements (including the spatial boundaries) for the deepwater and 

nearshore wave climates are described in the Waves Protocol. It will be necessary that the alongshore 

coverage of the nearshore wave transformation model matches that of the shoreline change model (i.e. 

with the ten times the shoreline projected alongshore extent of the borrow deposit(s)). 

4.0 TEMPORAL REQUIREMENTS 

4.1 Monitoring 

Beach and nearshore profiles and shoreline position should be surveyed twice per year, once in 

the late spring and once in early fall. The two sets of surveys must be completed every year following the 

initiation of dredging at the borrow deposit. 

Termination of shoreline monitoring for the purpose of determining possible impacts of dredging 

in Federal waters may only occur when the interpretation of the monitoring and modeling efforts clearly 

demonstrates there has been no impact to shoreline change and no further dredging of a borrow area is 

planned. In any event the termination of monitoring shall not occur before ten years after the cessation of 

dredging in a given borrow area. 

4.2 Modeling 

 Numerical model assessments of possible shoreline change impacts should be performed as 

follows: 

• Prior to initial dredging of the site in those cases where previous shoreline change modeling 

meeting the requirements of this Protocol has not been performed. 

• Once every five years following the initiation of dredging for a given borrow deposit area. 

• In the event that the sand body (where one exists) has been determined to have changed 

significantly based on a review of long term monitoring bathymetric survey comparisons. 

 Termination of shoreline modeling for the purpose of determining possible impacts of dredging in 

Federal waters may only occur when the interpretation of the monitoring and modeling efforts clearly 

demonstrates there has been no impact to shoreline change and no further dredging of a borrow area is 

planned. In any event the termination of modeling shall not occur before ten years after the cessation of 

dredging in a given borrow area. 

5.0 METHODS AND SPECIFICATIONS 

The monitoring and modeling of shoreline change is usually performed at two primary levels of 

detail: 

1. Assessment of the change in the shoreline position, in which case this variable is considered to be 

representative of the change to the entire littoral zone inshore of the closure depth; and 

2. Consideration of the change to the sea bed and beach surface (a greater level of detail). 
Protocols for Shoreline Monitoring and Modeling 

73 

For monitoring, the first level of assessment is completed through topographic surveys of a 

representative shoreline feature (e.g. high water mark, vegetation line or toe of foredune line) or more 

commonly the interpretation aerial surveys to define similar features. Modeling at this level of detail is 

completed through the application of a one-line shoreline change model, the most widely used being the 

Corps of Engineers GENESIS model (Hanson and Kraus, 1989). Obviously, this level of assessment 

provides a quantitative estimate of shoreline change (which is most important in the assessment of 

possible land side impacts of induced changes). However, it assumes that any erosion or deposition is 

occurring at the same rate across the beach and nearshore profile. 

Monitoring at the second level of detail ideally includes a combination of hydrographic and 

topographic surveys extending from the inshore toe of the primary dune out to the depth of closure. As 

topographic and hydrographic LIDAR surveys become more widely applied, this approach will provide 

for a comprehensive assessment of the total gain or loss of sediment from any given control volume. This 

level of detail would allow for a full assessment of the sediment budget (i.e., the evaluation of total net 

gain or loss of sediment from the active littoral zone). However, at present beach and nearshore profiles 

(usually at something in the range of 300 m spacing) are surveyed to provide some indication of the three 

dimensional nature of the changes. Unfortunately, there are no commonly accepted and applied 

numerical models for estimating the three-dimensional changes to the beach and littoral zone (at research 

or site specific level these types of models have been developed, tested and applied with varying degrees 

of success). This level of assessment provides a more comprehensive indication of changes that may be 

caused by external influences (such as offshore dredging). For example, dredging may lead to erosion in 

the nearshore zone and profile steepening with only limited shoreline change initially. Profile or 

hydrographic surveys would capture this level of change whereas shoreline surveys would not. 

Ultimately, changes to the shoreline will be observed. Therefore, the hydrographic survey information 

provides an early warning of changes to the nearshore that ultimately may lead to shoreline change. 

It is important note that it may be necessary to extend the bathymetry survey beyond the closure 

depth in instances where there may be a sediment transport supply pathway from an offshore deposit. 

Therefore, the offshore extent of the bathymetry survey must be considered on a site-specific basis and 

account for the possibility of more far-reaching sand transport processes. 

5.1 Monitoring 

Topographic and hydrographic profile surveys should be conducted of the beach and nearshore 

zone within the spatial boundaries identified in Section 3. Where State Coastal Zone Program 

requirements do not exist, profile surveys should be conducted at approximately 300 m spacing along an 

azimuth perpendicular to the shoreline. Where previous survey lines exist, these should be re-occupied. 

The hydrographic surveys should extend to a depth of closure or a minimum of 1,000 m seaward of mean 

high water, whichever is farther. Additional profile surveys should be conducted at intermediate stations 

adjacent to coastal protection structures or within localized areas of accelerated erosion. 

 With the exception of the drawing, plotting, line spacing or point density specifications, all 

requirements outlined under for Class II hydrographic surveys in EM1110-2-1003 (1994) and EC1130-2-

210 (1998) of the US Army Corps of Engineers or the Technical and Engineering Guide for Hydrographic 

Surveying by ASCE (1998) shall apply. Revised accuracy standards and related technical guidance 

contained in EC1130-2-210 supersede applicable portions of EM1110-2-1003. 

Where aerial survey requirements are not specified as part of a State Coastal Zone Management 

Program, shoreline delineation can be derived from stereo photogrammetry (either black & white or 

color) using tide-coordinated aerial photography controlled by kinematic Global Positioning Systems 
Protocols for Shoreline Monitoring and Modeling 

74 

(GPS) techniques. The derived mapping scale should be a common ratio such as 1:12,000 or 1:24,000 

scale vertical air photos. The specifications and standards as outlined in the American Society for 

Photogrammetry & Remote Sensing (ASPRS) Standards for Aerial Photography shall apply. The 

imagery should be suitable for digital orthoimagery production. 

 5.2 Modeling 

Shoreline modeling shall be performed with the GENESIS model (or an acceptable equivalent). 

The input wave data for the GENESIS model shall be derived from an acceptable wave transformation 

model as defined in the Waves Protocol. It is noted that the Corps of Engineers NEMOS package 

includes direct links between the STWave model and GENESIS together with pre- and post-processing 

software. 

The GENESIS model domain must comply with the spatial coverage outlined in Section 3. 

Application of the GENESIS model should follow the guidance of the Users Manual. 

The model must be calibrated for a hindcast period where concurrent wave and shoreline change 

data are available. Once calibrated, the model should be verified against an independent wave and 

shoreline change data set. Once these two steps are complete the model should be applied to determine 

the with and without project shoreline position at one year intervals for the next five years using five 

years of average annual wave conditions as input. The “without” project condition shall consist of the 

original pre-dredge configuration of the shoal. The “with” project condition shall be based on the most 

recent survey of the nearshore conditions in the vicinity of the borrow deposit. 

6.0 DATA DELIVERABLES 

 Nearshore profile survey results will be delivered in digital format (BPAS or EXCEL) with 

georeference information, and cross-reference to profile surveys at the same location. 

All aerial photos and derived shoreline position data files must be delivered in one or more 

georeferenced digital formats. The aerial photos should be differentially rectified to produce digital 

orthophotos, and cropped in such a manner to provide a manageable orthophoto mosaic and alignment 

with quadsheet boundaries. The orthoimages should follow the guidelines as defined in the most recent 

version of the Federal Geographic Data Committee (FGDC) Content Standard for Digital Orthoimagery. 

The recommended delivery format is GeoTIFF and TIFF with an accompanying TFW georeferencing 

world file. The shoreline position should be delivered as a line feature data set with an appropriate 

attribute table including fields that identify the shorelines' mean high water (MHW) and mean lower low 

water (MLLW) location and shore interface type. The recommended delivery format is SDTS, Arc 

Export (E00) or ArcView shapefile. All geospatial data should be submitted in the following datum and 

coordinate systems: North American Datum 1927 and 1983 (both NAD27 and NAD83 are required), and 

Universal Transverse Mercator (UTM) grid. All digital geospatial data products are to be accompanied 

by complete metadata documentation in the FGDC Content Standard for Digital Geospatial Metadata 

(CSDGM) format. 

For the wave modeling work the required deliverables are described in the Waves Protocol. For 

the GENESIS modeling, all input and output files must be submitted in digital format. Also, key results 

files including the calibration run, the verification run and predicted shoreline change with and without 

the dredging project must supplied in digital format. Georeference information must be provided for the 

GENESIS grid. A report describing the calibration, verification and application of GENESIS must also be 

provided. 
Protocols for Shoreline Monitoring and Modeling 

75 

7.0 REFERENCES 

ASCE, American Society of Civil Engineers. 1998. Hydrographic Surveying, Technical Engineering and 

 Design Guides as Adapted from the US Army Corps of Engineers No 25. 

Hanson, H. and Kraus, K. 1989. GENESIS: Generalized Model for Simulating Shoreline Change. Report 

 1. Technical Reference, Tech. Rept. CERC-89-19. 

USACE, United States Army Corps of Engineers. 1994. Engineering and Design, Hydrographic 

 Surveying, EM1110-2-1003. 

USACE, United States Army Corps of Engineers. 1998. Project Operations, Hydrographic Surveying, 

 EC1130-2-210. 
76

5.0 ADAPTIVE MANAGEMENT 

A key component of any long-term scientific study or monitoring program is the need to 

adapt the original study design and approach to reflect information and understanding gained 

from on-going studies during the execution of the program. For this reason it is the 

recommendation and assumption that the MMS will establish a permanent scientific 

review/advisory board to oversee the implementation and evolution of the OCS sand monitoring 

program and advise the MMS on the program components. Another key role of the scientific 

advisory board is to ensure the scientific validity and integrity of the monitoring programs and 

their findings. 

The scientific advisory board should include a benthic ecologist, physical oceanographer 

or specialist in sediment transport and movement, a bio-statistician, and a marine fisheries 

specialist. 

 Some of the areas that the project team envisions requiring input and recommendations 

by the advisory board to the MMS include: 

• Duration and frequency of sampling: The monitoring program design recommends 

collecting data at specific frequencies after a dredging event. Based upon the monitoring 

results to-date, it may be determined that monitoring may be required for a longer or 

shorter period or at more frequent intervals, for each program element.

• Inclusion of new or dropping of existing monitoring elements: The scientific advisory 

board should monitor program results carefully to validate the scientific value of each 

program element. If program results suggest that biological communities or 

geomorphological processes are being affected which are not part of the implemented 

monitoring program, then these elements will need to be added. Conversely, if a program 

element is not undergoing the expected change or not showing any effect or change as a 

result of dredging activities, then that element should be dropped from the program.

• Adapting the program to new locations: The current monitoring program was designed 

within the framework of the known OCS borrow locations and current dredging regimes. 

The program has been designed to measure the same core group of ecological parameters 

at each location. However, as new OCS sand borrow locations are identified or new 

dredging techniques are developed, it will be important for the scientific advisory board 

to ensure that the monitoring program, as implemented at each site, is conducted in a 

scientifically valid manner and that any critical adaptations necessary to ensure 

accomplishment of the original goals are included.

• Data synthesis and interpretation: The proposed monitoring program has the potential to 

generate data for multiple years at the same site as well as data for multiple years at 

multiple sites. It is important that the scientific advisory board ensures accurate and 

meaningful interpretation of these individual and cumulative data sets so that the MMS 

obtains the information it needs to assist it in resolving identified program resource 

management questions.
77

• Detecting regional differences: One of the scientific questions that the proposed 

monitoring program has been designed to attempt to answer is whether there are any 

regional differences in recovery or impact from OCS dredging activities. It will be 

important that the scientific advisory board ensures that any differences in recovery or 

impact in different regions are detected and reported.

 In addition to the above items, within the actual protocols there are items where a 

decision may need to be made by the scientific advisory board concerning a specific program 

element. 
78

6.0 COST ANALYSIS 

 In developing a cost estimate for the designed monitoring program, basic assumptions 

about the dredging operations needed to be made by the project team, such as the location of the 

borrow site, the potential size of the dredging operation, and distance of the borrow site from 

shore. To this end, the project team elected to select one of the MMS identified Regions of 

Interest (ROI) located along the Atlantic coast as a hypothetical project site, and to develop a 

cost estimate for the designed monitoring program for that location. The selected site was the 

Fenwick Shoal, Isle of Wight Shoal, and Weaver Shoal Regions of Interest located offshore the 

coast of Maryland and Delaware. 

 General program assumptions include: 

• Potential dredged area size is one kilometer (km) square by one meter (m) depth. 

• Dredging would be along the top of the ridge feature. 

• Dredging would occur using either a trailing suction hopper dredge or a cutter head 

suction dredge. 

• The dredge site is relatively close to shore and ship transit time from a nearby port is 

minimal. 

• Survey vessel size and design are such that 24-hour operations are possible, and all but 

the most inclement weather would prevent survey work from occurring. 

• Because of differences in regional labor costs, a range for labor rates is used. 

• No estimate of travel costs or equipment shipping costs is included in the cost estimate. 

• All cost estimates are in 2001 dollars and may need to be adjusted for inflation and 

technological/commercial advances in future years. 

 In addition to the assumption for the overall program, specific assumptions for each 

monitoring program element were made. These assumptions are detailed below along in the cost 

estimates for each program element. 

6.1 Physical Program Elements 

 The monitoring/modeling program targeted at the physical processes includes the 

following elements: 

• Hydrographic surveys; 

• Definition of deepwater and nearshore wave climate; 

• Monitoring and modeling of shoreline change; and 

• Grain-size analysis for sediment samples. 

Cost estimates for each survey and/or assessment are provided in the following sub-sections. 
79

6.1.1 Hydrographic Surveys 

Assumptions: 

• According to the required buffer area the total survey area for this example (1 km2

 dredge 

area) is 3 km2

. 

• Three possible alternatives to completing the hydrographic surveys are acceptable: 1) 

single beam acoustic with side scan sonar survey; 2) multibeam acoustic survey; and 3) 

Airborne LIDAR, such as the Corps’ SHOALS system. 

• Cost estimates are for a single survey. No time has been allotted for weather downtime. 

• The single beam/side scan sonar survey estimates are based on utilizing a vessel of 

opportunity in the nearest port and the multibeam estimate is based on a dedicated 60-

foot survey vessel. 

• It is noted that the initial two surveys prior to and immediately following dredging are 

required for payment under the dredging contract. It is recommended that the surveying 

for contract payment follow the Bathymetry Protocol to avoid duplication of effort. 

Cost Estimate: 

Single Beam/Side Scan Sonar Survey 

• Survey scope (determined from protocol) is 25 m spaced survey lines with 100 m cross 

lines for a total of 134 single beam survey line kilometers and 20 km of side scan sonar 

survey line. 

• Equipment and personnel included: survey vessel and personnel; surveyor; side scan 

sonar operator; DGPS and hydrographic survey software; single beam echosounder 

system; motion sensor; tide gage; and side scan sonar system. 

• The estimated survey time is two days for mobilization/demobilization and two days of 

survey time at a day rate of $3,900/day. 

• The total estimated cost including survey costs, processing operations report, bathymetry 

map and side scan sonar mosaic is in the range of $35,000 to $45,000. 

• The additional cost for difference mapping and a report detailing changes to the seabed 

(compared to previous surveys) is estimated to be $7,500. 

Multibeam Survey 

• Line spacing for a multibeam survey will vary according to system and water depth. A 

water depth of 7.5 m has been assumed for this site with 3.5x water depth swath width 

and 10 percent beam over lap. 

• Equipment and personnel include: dedicated multibeam survey vessel and personnel; 

surveyor; multibeam operator; multibeam acquisition system; MVP-30 velocity profiler, 

navigation software; and tide gage. 
80

• The estimated survey time is two days for mobilization/demobilization and one day 

surveying at an estimated day rate of $8,800/day. 

• The total estimated cost including survey costs, processing operations report, bathymetry 

map and backscatter mosaic is in the range of $48,000 to $60,000. 

• Additional cost for difference mapping and report detailing changes to the seabed is 

estimated to be $10,000. 

LIDAR Survey with Corps of Engineers SHOALS System 

• If the Corps of Engineers were mobilized in the area for other purposes (i.e., the 

mobilization cost was covered by others) the survey cost would be in the range of 

$10,000 to $15,000. 

• Mobilization cost would be on the order of $75,000 if the Corps were not operating in the 

area when the survey is required. However, it is unlikely such a small project would be 

scheduled with priority. 

• It is expected that by 2004 the SHOALS approach will be commercialized and more 

widely available. 

• Additional cost for difference mapping and report detailing changes to the seabed is 

estimated to be $10,000. 

6.1.2 Wave Monitoring and Modeling 

Assumptions: 

• There is a directional wave buoy (NBDC44009) located approximately 19 km directly 

offshore of the hypothetical borrow site at Fenwick Shoal (offshore of the MarylandDelaware border). This buoy is close enough and provides sufficient temporal data 

coverage that a site specific buoy would not be required. Nevertheless, for the purposes 

of providing cost information we have assumed that a buoy will be deployed at the 

location of the existing buoy. 

• It is possible that where a new buoy is required, that NOAA may cover part of the 

purchase and deployment cost. This has not been considered in our cost estimate. 

• Wave transformation costs have been determined to cover the offshore, borrow and 

nearshore regions as described in the Waves Protocol. 

• The costs are for an assessment of the wave transformation for two cases considering the 

bathymetry before and after dredging. This will be required in the initial assessment 

prior to each dredging project. It is possible some interim assessments may only require 

one transformation case and a reduction in the overall cost for this situation is presented. 

Cost Estimate: 

• The cost of purchasing and deploying a directional wave buoy with the capacity to 

transmit real-time data to shore is in the range of $60,000 to $80,000. 
81

• The annual maintenance cost including both data management and physical maintenance 

of the buoy and moorings is estimated to be in the range of $10,000 to $20,000 per year. 

• Preparation of the deepwater wave climate for transformation to shore is estimated to cost 

$5,000 to $7,000. 

• Offshore Region wave transformation to develop the wave climate at the site is estimated 

to cost $8,000 to $12,000. Note that this is the initial cost. Once the grid is available for 

future assessments, the cost of this task will be reduced by 50 percent. 

• Borrow Region wave modeling is estimated to cost $18,000 to $24,000 for an assessment 

of two bathymetry cases. The cost would be reduced by $10,000 for a single bathymetry 

case assessment. 

• Nearshore Region wave modeling is estimated to cost $12,000 to $16,000 for an 

assessment of two different wave climates (i.e., for the different bathymetry grids 

evaluated under the Borrow Region modeling). Two assessments will always be required 

for the Nearshore Region to evaluate shoreline changes with and without the bathymetry 

changes in the borrow region. 

• Reporting and preparation of data for delivery in the required format is estimated to cost 

$10,000 to $15,000. 

6.1.3 Shoreline Monitoring and Modeling 

Assumptions: 

• Most states have some form of shoreline monitoring program in place that collects 

nearshore profiles and aerial photos. Therefore, only a very rough estimate of costs to 

collect and process this information has been provided. 

• It has been assumed that the shoreline modeling is performed with the U.S. Army Corps 

of Engineers GENESIS model within the NEMOS software that is part of the CEDAS 

package. This is by far the most widely applied shoreline change model. 

• The estimates are based on the application of the model to a 10 km reach of shoreline 

centered on the hypothetical borrow deposit based on the application of the Shoreline 

Protocol requirements for a 1 km long borrow area. 

• There will be two main steps to the shoreline change modeling as outlined in the 

Shoreline Protocol: 1) calibration and verification; and 2) prediction of shoreline change 

with and without dredging project wave climates. 

Cost Estimate: 

• The cost of surveying and processing data for 20 or more nearshore profiles would be in 

the range of $1,800 to $2,400 per profile. The cost for 10 km reach of shore with 300 m 

spacing on the profiles and two surveys per year would be $120,000 to $160,000. 

• The cost of taking aerial photos and registering these images for a 10 km reach of 

shoreline would be $20,000 to $40,000. 
82

• The cost of calibration and verification of the GENESIS model within the NEMOS 

package is estimated to be in the range of $5,000 to $10,000. This calibration only needs 

to be completed for the initial assessment. 

• The cost of completing GENESIS model runs with and without the proposed dredging 

project is estimated to be in the range of $3,000 to $6,000. 

• It is estimated that the cost of preparing a report that presents and interprets the results of 

the monitoring and modeling would be in the range of $10,000 to $15,000. 

6.1.4 Grain Size Analysis 

The cost of retrieving and analyzing the samples for grain size testing (including hydrometer 

analysis) has been included under the Benthic Field Sampling program costs. The cost of grain 

size analysis for individual samples is approximately $100 per sample. 

6.2 Biological Program Elements 

 The biological monitoring program is based on the following general assumptions: 

• Each monitored dredge site would have both impact and one control sampling locations. 

• Each monitored dredge site would have a minimum of four strata at the control and 

impact sampling locations. These strata correspond to the ridge top (dredge site), steep 

sloped ridge face, shallow sloped ridge face, and low valley or plain located at the base of 

the steep slope ridge face. For broad shelf borrow areas the fourth strata is eliminated, 

and the steep sloped and shallow slope ridge features are replaced by leading edge and 

trailing edge areas of the seafloor adjacent to the dredge borrow site and oriented along 

the predominant wave and seafloor sediment movement. 

• Cost estimates are per a single survey (pre-impact, year 1, year 3, year 5 or year 7). 

• No cost estimates are made for marine mammal and wildlife monitoring since there are 

too many unknown parameters (number of observers required, number of days of 

dredging, project-specific environmental mitigation requirements to avoid collisions and 

harmful interactions with marine wildlife, etc). It was also assumed that, because of the 

expected imposition of environmental mitigation requirements to prevent collisions or 

harmful interactions with marine wildlife, the cost of this component of the monitoring 

program would be born by the dredging operation. 

6.2.1 Benthic Field Sampling and Analysis 

Assumptions: 

• Because of different manning and equipment requirements, the benthic and fish data 

collection efforts could be combined and conducted at the same time or split into separate 

survey legs or phases. For the purposes of cost estimating, it was assumed that these 

sampling efforts would be done on separate survey legs. 
83

• For the purposes of establishing a budget estimate and based on the study design and data 

collected by previous MMS surveys of OCS sand borrow areas, it is estimated ten benthic 

grabs will be collected at each of four strata at both the dredge and control sites, for a 

total of 80benthic grab samples. The actual number of samples collected at each strata 

will need to be determined from samples collected during the pre-dredging baseline 

survey in accordance with the procedures outlined in the sampling protocols. 

• The benthic sampling field leg will require three scientific personnel and will be 

conducted during daylight hours. 

• Once on site, the time required to collect the grab, initiate sample processing and move to 

the next location is one hour. 

• Three to four days will be required to collect all of the requisite samples. No time has 

been allotted for weather downtime. 

• Transit to and from the survey site requires less than one day total. 

• A vessel of sufficient size and capacity will be used that will allow staying on-site during 

each leg of the field effort. 

• Grain size analysis and Total Organic Carbon (TOC) analysis will be performed on subsamples form all benthic grabs. A total 80 samples will be analyzed. 

Cost Estimate: 

• Costs for the survey vessel (including crew) is estimated to be $2,500 to $3,500/day. 

Total vessel cost for four days of surveying and two additional days of 

mobilization/demobilization and transit is estimated to be $15,000 to $21,000. 

• Labor rates for the scientific personnel will be $650/day to $800/day (12 hour days), 

depending on experience and qualification. Total scientific labor cost will range between 

$11,750 and $14,400.

• Incidental costs associated with local travel of personnel, field sample equipment, and 

miscellaneous sampling supplies are estimated to be $2,500 to $3,000. 

• Analysis of benthic infauna will be $750 to $1,250 per sample, depending on the 

complexity and species diversity of the benthic infaunal community. Total estimated cost 

will range between $60,000 and $100,000, depending on the total number of samples 

collected and the actual cost of the analysis. 

• Grain size and TOC analysis will be $125-$175 per sample ($75-$100/sample for grain 

size and $50-$75/sample for TOC). Total estimated cost is $10,000-$14,000.

6.2.2 Fish Field Sampling and Analysis 

Assumptions: 

• Because of different manning and equipment requirements, the benthic and fish data 

collection efforts could be combined and conducted at the same time or split into separate 

survey legs or phases. For the purposes of cost estimating, it was assumed these 

sampling efforts would be done on separate survey legs. 
84

• Two to five bottom trawls will be required at each of the four strata at the control and 

dredge sites (12-30 trawls total) to collect sufficient fish samples for gut contents and to 

identify the dominant resident fish species. Trawls will be conducted both during 

daylight hours and at night. 

• All fish trawls will be conducted within four days with an additional two days of 

mobilization/demobilization and transiting to the survey site. 

• The fish sampling field leg will require six scientific personnel to accommodate day and 

night sampling (three per half day). The number of personnel is based on the assumption 

that for each crew shift, two of the scientists will be responsible for collecting 

information on each fish sample and remove the fish guts and muscle tissue samples. 

The third scientist will be responsible for recording data and ensuring all samples are 

properly labeled and processed. 

• Each trawl will be analyzed in the field. Fish muscle tissue samples and fish gut contents 

samples will be collected, properly preserved, and shipped to the laboratory for analysis. 

• For the purposes of establishing a budget estimate, it has been assumed that 

approximately 30 gut-content samples per each of three species will be collected from 

each of the four sampled strata at both the dredge site and control site, for a total of 720 

fish-gut content samples. The actual number of samples collected at each strata will need 

to be determined from samples collected during the pre-dredging baseline survey in 

accordance with the procedures outlined in the sampling protocols. 

Cost Estimate: 

• The survey vessel (including crew) is estimated to cost $3,500 to$4,500/day, to 

accommodate 24-hour operations. Total vessel cost for four days of surveying and two 

additional days of mobilization/demobilization and transit is estimated to be $21,000 to 

$27,000. 

• Labor rates for the scientific personnel will range between $650/day and $800/day (12 

hour days), depending on experience and qualification. Total scientific labor cost will 

range between $23,400 and $28,800.

• Incidental costs associated with travel of personnel, field sample equipment, sample jars, 

preservative, etc. are estimated to be $2,500 to $3,000. 

• Fish gut contents analysis is estimated to cost $55 to $85 per sample. Total analytical 

costs will be $39,600 to $61,200.

6.2.3 Stable Isotope Analysis 

Assumptions: 

• Samples will be collected either during field sampling (fish muscle tissue) or during 

laboratory analysis (benthic infauna). 

• A total of 120 benthic infaunal stable isotope samples will be analyzed [3 replicates x 5 

benthic species/faunal group x 4 strata x 2 sites (control and impact)]. 
85

• A total of 72 fish stable isotope samples will be analyzed (3 replicates x 3 fish species x 4 

strata per site x 2 sites (control and impact). 

Cost Estimate: 

• Stable isotope samples are estimated to cost $50 to $75/sample. 

• Benthic infauna stable isotope sample analysis is estimated to cost $$6,000 to $9.000. 

• Fish muscle tissue stable isotope sample analysis is estimated to cost $3,960 to $5,400. 

6.2.4 Data Analysis and Reporting 

Assumptions: 

• Minimal data analysis and interpretation would occur following the baseline survey. 

More detailed data analysis and interpretation would occur following each post-impact 

survey (years 1, 3, 5 and 7). 

• As the number of surveys increases, data comparison with previous years surveys 

increases and may require additional effort.

Cost Estimate: 

• Estimated cost for data analysis, interpretation and preparation of a report is $30,000 to 

$45,000. 

6.3 Summary of Estimated Costs 

 The low and high range cost estimates for the designed OCS sand dredging monitoring 

program are summarized in Table 6.1. At most locations (i.e., the State is already surveying 

nearshore profiles and taking aerial photographs and where a wave buoy is not required) for most 

surveys (i.e., other than the initial survey and for cases where a site is accessed for sand removal 

on a frequent basis), the cost of implementing the monitoring protocols will be in the $349,110 to 

$541,750 range (i.e., Total 4). In cases where a site is only accessed once, Total 3 would be the 

monitoring costs. It is also noted that at least part of the hydrographic survey component of this 

cost ($70,000 to $120,000) is required for payment on the dredging contract (i.e., would be 

completed regardless of the Protocols). 

In the event that the monitoring program is required for a full seven years, totals for a 

variety of possible outcomes have been determined and are presented in Table 6.2. In all cases it 

has been assumed that bathymetry as changed to the extent that wave transformation modeling 

(Item 1.4 in Table 6.1) is required. It is likely that for many locations other agencies will cover 

the costs of nearshore profile monitoring and aerial photographs and that a dedicated wave buoy 

will not be required. Also, the estimates in Table 6.2 assume that the site is dredged only once at 

Year 0. 
86

Table 6.1. Low and high cost estimates for the designed monitoring program, for pre-dredging, 

immediate post-dredging, and Year 1 shoreline monitoring activities plus estimates 

for seven years of monitoring.

 Physical 

Parameters Program Element 

Low $ 

Estimate 

High $ 

Estimate 

1.1 Hydrographic survey with single beam & side scan 

sonar or multibeam (includes 1 pre-dredging and 1 

post-dredging surveys) survey 

$70,000 $120,000 

1.2 Report on seabed change $7,500 $10,000 

1.3 Wave buoy (if necessary) (does not include 

$10,000-20,000 annual maintenance cost) 

$60,000 $80,000 

1.4 Wave transformation modeling (cost will be 

reduced by $20,000 after initial assessment) 

$43,000 $59,000 

1.5 Report and data delivery - Waves $10,000 $15,000 

1.6 Nearshore Profiles (if necessary) 2 surveys in the 

first year post-dredging 

$120,000 $160,000 

1.7 Aerial photography and registration $10,000 $20,000 

1.8 GENESIS calibration/verification (initial 

assessment only) 

$5,000 $10,000 

1.9 GENESIS model tests with and without project $3,000 $6,000 

1.10 Interpretation and reporting on shoreline change for 

Year 1 

$10,000 $15,000 

 Sub-total $338,500 $495,000 

Biological 

Parameters Program Element 

Low $ 

Estimate 

High $ 

Estimate 

2.1 Benthic and Sediment Field Sampling Effort $26,700 $35,400 

2.2 Fisheries Field Sampling Effort $44,400 $55,800 

2.3 Benthic Infauna Sample Analysis $60,000 $100,000 

2.4 Incidental Field costs $5,000 $6,000 

2.5 Fish-Gut Contents Analysis $39,600 $61,200 

2.6 Grain Size and TOC Analysis $10,000 $14,000 

2.6 Infauna Stable Isotope Analysis $6,000 $9,000 

2.7 Fish Stable Isotope Analysis $3,960 $5,400 

2.8 Data Analysis & Reporting $30,000 $45,000 

Sub-Total $166,450 $291,750 

TOTAL 1 All Items - Year 1 $564,160 $826,800 

TOTAL 2 Without Wave Buoy (Item 1.3) – Year 1 $504,160 $746,800 

TOTAL 3 Without Wave Buoy (Item 1.3), Nearshore Profiles 

(1.6) or Aerial Photography (1.7) – Year 1 

$374,160 $571,800 
87

Table 6.2 Low and high cost estimates over seven years for different scenarios (note: totals are 

not discounted for time to present day dollars). 

Scenario Low $ 

Estimate 

High $ 

Estimate 

1. Full Requirements $2,164,800 $3,429,000 

2. No Wave Buoy Required $2,034,800 $3,244,000 

3. Nearshore Profile and Air Photo Surveys by Others (with buoy) $1,324,800 $2,309,000 

4. Nearshore Profile and Air Photo Surveys by Others (without buoy) $1,194,800 $2,124,000 
88

7.0 INFORMATION GAPS 

 In conjunction with the monitoring program design and assessment of each program 

element, the project team identified information gaps that will need to be addressed either prior 

to the implementation of the monitoring program or concurrent with its implementation. These 

gaps include: 

• Are there procedures to dredge shoal and ridge features that will minimize ecological 

impacts and/or speed recovery, such as dredging completely one specific shoal or ridge 

and leave adjacent features un-touched vs. dredging a small amount of sand from each 

shoal or ridge feature, or dredging in strips leaving undisturbed areas that act as local 

sources of recruitment and allow recruitment from older life stages, as supported by the 

work conducted by Whitlatch et al. (1998). 

• Are there gaps in baseline data, both biological and geomorphological, at each candidate 

OCS dredging site? Although some site characterization data have been gathered at some 

locations, the data and information are such that they will not suffice for establishing an 

accurate "before impact" data set. 

• What is the use and role of sand ridges and shoals as potential "essential fish habitat" by 

migrating or resident fish? Many researchers suggest that these topographic features 

perform some critical function in supporting fish stocks, either during migration or as 

habitat for spawning/juvenile fish. However, there are limited data to confirm or 

disprove this belief. 

• Are there benthic biological differences that run longitudinally along the ridge and shoal 

features that may affect the proposed sampling design and require further stratification? 

 

• Can the relationship of carbon and nitrogen stable isotopes and trophic level improve the 

scientific knowledge of how the alteration of organic matter and benthic invertebrate 

communities affect the population of bottom feeding fish in an anthropogenically 

disturbed and recovering area of the ocean? 

• Is there a preferred manner to remove sand from a shoal/ridge feature to maximize their 

use and maintain the integrity of the feature? For example, there are currently concerns 

that certain dredging practices results in the accumulation of fine-grained sediments in 

the burrow areas, making the site unsuitable for re-use. Also, there are questions about 

where on ridges is it best to dredge to speed recovery and reduce long-term impacts. 

 Several of the key questions related to data gaps are concerned with the nature and 

characteristics of ridge and shoal features. As a result, and considering that the majority of 

deposits that have been identified thus far fall into this category, a preliminary review of the 

literature was completed to assemble what is know about physical and biological processes 

associated with these features. Section 7.1 presents a summary of this review. 
89

 It is important to note that while the majority of potential OCS borrow deposits identified 

to date consist of ridges and shoals, in the future it is likely that the range of deposit types will be 

expanded to include paleo-channels, paleo-deltas, and other buried sand deposits. It is has been 

postulated that while ridges and shoals are more readily (and less costly) to identify in the first 

place, it is likely that more economic (i.e., larger and closer to shore) and higher quality buried 

deposits will be discovered within federal waters. 

7.1 Characteristics of OCS Shelf Sand Ridges and Shoals 

7.1.1 Definition and Occurrence 

There are several different kinds of sand bodies present on the continental shelf of the 

USA, but this discussion will focus primarily on sand ridges and swales that are located on the 

inner/upper continental shelf and oriented obliquely to the predominant/prevailing wave 

approach direction. One of the first comprehensive descriptions of these occurrences on the 

continental shelf off the east coast of the USA was by Uchupi (1968). His map, shown in Figure 

7.1, illustrates the features he termed sand swells and described as follows: 

Figure 7.1. Sand swells on continental shelf from New York to Cape Kennedy. 

Curved lines indicate crests of sand swells (from Uchupi, 1968). 
90

1) Radiating clusters near the mouths of estuaries 

2) Arcuate, seaward convex ridge systems near cuspate forelands 

3) Shoreface ridge and swale systems 

4) Broadly spaced ridges and swales on open shelf 

Types 3 and 4 will be emphasized in this discussion. 

Other types of sand bodies preserved on the shelf that could provide sand for beach 

renourishment include; (1) overstepped barrier islands (e.g., Ship Shoal off the Mississippi 

Delta); (2) estuarine entrance shoals (both active and inactive; e.g., off St. Helena Sound, South 

Carolina); (3) large ebb-tidal deltas off major tidal inlets (e.g., off inlet to Mobile Bay), (4) delta 

lobes deposited at lower stands of sea level (common off Santee Delta, South Carolina); (5) 

features associated with low stand river valleys (present on shelf off Texas and North Carolina); 

(6) tidal sand ridges (off New England and Alaska); and possibly others. 

The best examples of ridge and swale topography on the North American continental 

shelf occur in the following areas: 

1) Mid-Atlantic Bight (Fig. 7.2) 

2) Northeastern Gulf of Mexico (off coasts of Alabama and northwest Florida; Fig. 7.3) 

3) Sable Island Bank, eastern Canada (Fig. 7.4) 

Note that in every case, the ridges are oriented directly into the predominant/prevailing or 

storm wave direction. Waves approach from the northeast in mid-Atlantic Bight (during 

“nor’easters”), from the southeast off Alabama, and from the southwest on Sable Bank. This fact 

seems to imply a common process for the origin and maintenance of these features. 

Table 7.1, summarized from the data for the Maryland shelf (slightly modified from 

Swift and Duane, 1981) and for global sand ridges (including tidal sand ridges) (from Snedden 

and Dalrymple, 1999), lists the general characteristics of sand ridges. 

 The grain size trends commonly observed on the sand ridges off Sable Island and New 

Jersey are illustrated in Figure 7.5. Coarsest sediments occur in the swales and on the updrift 

sides of the ridges (i.e., northwest side of New Jersey ridges and west side of Sable Island 

ridges). This pattern appears to be typical for ridges in <20 m depths. This observation implies 

that the coarser sediment is a lag-like deposit that acts to stabilize the ridge to some extent. 

In any event, it seems clear from the numerous studies that have been conducted within 

the last two decades, that once formed, most ridges in depths <20 m are maintained and even 

enlarged by present-day hydrodynamics (Snedden and Dalrymple, 1999). It also seems clear that 

there is an evolutionary progression in an offshore direction as the influence of waves 

diminishes. The contrast of storm and fair-weather conditions on the ridges, in both nearshore 

and offshore areas, as envisioned by Snedden and Dalrymple (1999) is given in Figure 7.6. 

Measurements of currents during a storm imply that storm-generated currents do run obliquely 

offshore and across the crest of a shoreface attached-ridge in New Jersey (Fig. 7.7; from Snedden 

et al. 1994). 
91

Table 7.1. General characteristics of sand ridges summarized from the data for the Maryland 

shelf (slightly modified from Swift and Duane, 1981) and for global sand ridges, 

including tidal sand ridges (from Snedden and Dalrymple, 1999). 

Criteria Maryland Global

orientation perp. to wave approach flow-oblique 

symmetry asymmetrical near shore asymmetrical 

relief 3-12 m 5-40 m 

horizontal width 0.9-2.8 km 0.7-8 km 

spacing 1.5-11.1 km - 

maximum side slopes 0.2-7 degrees <1-7 degrees 

grain size fine to coarse sand fine to coarse sand 

lateral trends (grain size) stoss side coarser than lee side stoss side coarser 

superimposed bedforms ripples to sand waves ripples/sand waves 

 Goff et al. (1999) state that “in depths >20 m, ridges have not continued to grow since 

transgression has brought them into the offshore hydrodynamic regime”. Many studies have 

concluded that there is reworking of the tops of the ridges located further offshore, but few imply 

that the ridges have been completely reformed. 

7.1.2 Theories for Origin 

The Ship Shoal off the coast of Louisiana, which was treated in a comprehensive study by 

Penland et al. (1986), is discussed first. Their study included vibracoring, age dating, seismic 

profiling, fossil assemblage studies, etc. The shoal, located in 3-10 m water depths, has a 5 m 

thick core that was clearly defined as a barrier island deposit in that study. However, the shoal is 

asymmetric landward, implying some modification and reworking by waves. Preservation of a 

relict barrier island of this magnitude can only occur on shorelines that are sinking rapidly, which 

is certainly the case for the Mississippi delta lobe that the barrier island was associated with. 

That delta lobe was abandoned when the river mouth switched to a new position. On 

tectonically stable shelves, such as Maryland and Alabama, any such low-stand barrier islands 

that may have been present in those areas, owing to a stabilization of sea level for some period of 

time, were eroded away during the slow rise of the sea after formation of the islands. Some 

authors, such as Stubblefield et al. (1984) and others, do believe that remnants of relict barrier 

islands are still preserved on the middle continental shelf of the Mid-Atlantic Bight, but none 

have been proposed for depths as shallow as the Ship Shoal, at least not in the more recent 

literature. 
92

Figure 7.2. Bathymetry of the Assateague ridge field, contoured from National 

Ocean Survey smooth sheets. Ridges are designated by letters. Contour interval: 

10 feet. (From Swift and Field, 1981).
93

Figure 7.4. (a) Bathymetry (in metres) of the area surround Sable Island, 

with crestline positions of the shoreface-attached ridges and locations of 

morphological zones discussed in the text (B) Location of grain-size 

transects, sidescan and seismic profiles, and vibrocores shown in 

subsequent figures. From Hoogondoorn and Dalrymple (1986).

Figure 7.3. Study area in the northeastern Gulf of Mexico showing detailed 

bathymetry at 5 m contour intervals. Thicker contours are at 25 m intervals. 

North and South Perdido Shoals trend northeast - southwest on the mid-shelf 

area. From McBride et al. (1999). 
94

 

 (A) (B) 

Figure 7.5. Trends in texture of surficial sediments over shoreface sand ridges. 

A) Sable Island, Nova Scotia. B) Peahala Ridge, New Jersey. Note offset between the 

bathymetric and grain-size profiles. From Snedden and Dalrymple (1999).

Figure 7.6. Storm and fair-weather dynamics and ridge migration in 

nearshore and offshore areas. Based on current meter reported in Snedden et 

al. (1994) and McClelland (1973b) and bathymetric surveys of McHone 

(1973). From Snedden et al. (1999). 
95

 The development of ridge and swale topography of the type under discussion here seems 

to be favored by the following conditions: 

1) A wide, sandy continental shelf with a moderately abundant sand supply, either from 

riverine sources, erosion of the shoreline as the sea level rises, or from sediment brought 

to the shelf during periods of glaciation and/or ice melt. 

2) Rising sea level over a widening shelf. 

3) Drowned bathymetric irregularities that act as nuclei for the ridges. 

 Ridges and swales do not occur on prograding delta fronts or other intensely prograding 

areas, especially those with high rates of mud deposition. Based on the limited literature search 

completed, they do not occur on macrotidal coasts, but apparently there are some off the 

mesotidal coast of Western Europe. The center of the Georgia Bight, which has the largest tides 

along the east coast of the USA south of Maine as well as an abundant muddy sediment source, 

does not have near the number of ridges as seen in the Mid-Atlantic Bight area. 

 Early studies on the Mid-Atlantic Bight recognized a need to explain the puzzling fact 

that the ridges were parallel to each other, seeming to mimic earlier ridges out on the shelf, and 

that they were oriented directly into the dominant northeasterly wave approach direction. Swift 

et al. (1973) and later authors of the same group concluded that the ridges were derived from the 

shoreface of barrier islands as they retreated across the continental shelf in response to rising sea 

level. Over time, these new shoals broke away from the barrier islands and retreated to the 

southwest as the barrier island continued to migrate landward. In order to explain how the ridges 

were maintained, these authors called on storm-generated helical secondary flow structure and 

storm wave surge, which resulted in converging bottom currents that aggraded the ridge crests. 

This model is illustrated in Figure 7.8. 

Figure 7.7. Orientation of near-bottom, peak storm current and wave motion 30-

31 March 1985. Current meters V1 and V2, which are located outside map area, 

are shown for reference. From Snedden et al. (1994). 
96

Numerous other theories have been proposed, none of which dispute the importance of 

rising sea level and an abundant sand supply. One of the more interesting ones is the theory of 

Boczar-Karakiewicz and Bona (1986), which states, “On wave-dominated shelves, a mechanism 

that may account for systems of sand ridges is associated with the development of infragravity 

waves”. These waves have periods ranging from 30 seconds to 5 minutes. This theory does 

seem to account for the number and parallelism of some of the ridges, but even the authors admit 

that issues such as how the sediment gets onto and is dispersed along the shelf and what 

mechanisms lead to the development of the ridges are unknown to them. 

Another theory of formation has been prepared by Trowbridge (1995), who once again, 

discussing the ridges on the Mid-Atlantic Bight shelf, states that storm-driven southerly currents 

veer offshore over the ridge crests. This is apparently true, as the data of Snedden et al. (1984; 

see Fig. 7.7) clearly show. Trowbridge also states that the “exponential growth of shore-oblique 

features is a result of offshore deflection of storm-driven alongshore flows at ridge crests, which 

leads to convergence of sediment flux because the effective carrying capacity decreases with 

increasing distance offshore.” 

 One of the more widely quoted theories is that of Huthnance (1982), even though it was 

originally proposed to explain the tidal sand ridges in the North Sea, which are clearly related to 

tidal activity. In any event, the Huthnance model has the following requirements: 

1) Irregularities exist on a sandy bed 

2) The current runs around and over these irregularities 

3) Upcurrent side starts to accrete 

4) Then upcurrent side eroded with sand being deposited on crest of new feature which 

causes it to grow upward and migrate down current 

5) Maximum growth is oblique to flow direction 

6) Grows until “equilibrium profile” is reached 

7) No more active growth 

8) Waves would erode the ridge but currents counteract wave action, maintaining the ridge 

Figure 7.8. Schematic diagram of secondary flow motions (helical flow structure) and 

storm wave surge believed to be associated with storm flow field. From Swift et al. 

(1973). 
97

 There are three major constraints that must be met in order for this theory to work: (1) a 

sufficient quantity of loose sand (no problem); (2) currents capable of moving the sand; and (3) a 

pre-existing irregularity. 

In order to take issue three into account, many of the recent workers favor an idea 

presented by McBride and Moslow (1991), which is outlined in Figure 7.9. Under this theory, 

the “pre-existing irregularity” is the ebb-tidal delta of an inlet through the adjacent barrier island. 

The inlet migrates downdrift, leaving a piece of its ebb-tidal delta behind that becomes the core 

of the new sand ridge formed by the process outlined by Huthnance. The inlet continues to 

migrate until it eventually closes and a new inlet forms and the process starts all over again. 

Snedden and Dalrymple (1999), in an excellent paper on sand ridges, are strong proponents of 

this idea, and indicate that the migrating inlet somehow is responsible for the swale on the 

landward side of the new ridge. There are limitations and outstanding questions with all of these 

theories so the search for the universal precursor (initial irregularity) of sand ridges continues, to 

fulfill the Huthnance theory. There could be any number of possible initial irregularities, as 

suggested by Snedden and Dalrymple (e.g., submerged pieces of relict barrier islands). 

In the evolutionary progression for the sand ridges proposed by Snedden and Dalrymple 

(1999), the ebb-tidal delta precursor may eventually be either left behind or eroded away as the 

migrating ridge works its way offshore (illustrated in Fig. 7.10). 

One process that has received little attention in the literature is the influence of wave 

action on these features. As part of this study, a Boussinesq wave model (phase resolving) was 

applied to assess the influence of waves on the group of shoals offshore Maryland/Delaware 

Figure 7.9. Evolution of ridges on the New Jersey Atlantic Shelf, USA. The first 

three evolutionary phases depicted here (ebb-tidal precursor, attached-ridge) are 

modified after McBride and Moslow (1991). From Snedden et al. (1999). 
98

(Fenwick, Weaver and Isle of Wight Shoals). The results for a 1-m, 16-s wave from the ENE are 

shown in Figures 7.11A-C. Figure 7.11C is a snapshot of an animation which clearly 

demonstrates together with Figure 11B that the waves converge over the crest of the shoal. 

Shoaling waves and the related orbital velocities in these water depths are non-linear and 

generally result in sand transport in the direction of wave attack. Therefore, over the crest of the 

shoal the converging waves would head to a convergence of sand transport. This process could 

explain how these features are maintained over time. 

Figure 7.10. Schematic diagram of ridge classes. The precursor in the case of the Class 1 

and 11 ridges is a pre-existing bathymetric feature, sometimes associated with a shoreline or

inlet, which provides the nucleation point for the ridge via the Huthnance process. 

Subsequently, this precursor may be removed or reduced in size through current erosion and 

ridge migration. Accretion on the landward side of the juvenile ridge (Class 1) is largely 

induced by fair-weather wave transport from the ridge crest and is not expected to occur in 

ridges developed in deeper water, as with Classes II and III. New ridge sand is primarily 

deposited in shelf waters by combined flows associated with storm passage. From Snedden 

and Dalrymple (1999). 
99

 Another formation process or explanation of origin for ridge and shoal features relates 

to stratigraphically controlled features. These consist of sand deposited over Pleistocene 

sediment units and are particularly prevalent along the North Carolina coast (Stan Riggs, pers. 

comm.) The stratigraphy of such features has important implications to the size of sand reserves 

and the potential impacts of dredging.

Figure 7.11A. Bathymetry of shoals offshore Maryland/Delaware border 

(depths and x-y axes in meters). 
100

Figure 7.11B. Wave heights predicted by a Boussinesq wave model for shoals 

offshore of the Maryland/Delaware border (incoming wave: Hs=1 m, Tp=16s, 

ENE). 
101

Figure 7.11C. 3D view of three shoals. 
102

7.1.3 Future Formation and Mobility of the Ridge Features 

Sand ridges will continue to form in the future providing there is enough sand available 

for ridge formation. Ridge formation continues at the present time, as evidenced by the presence 

of numerous shoreface-attached ridges in the two study areas (Alabama and Mid-Atlantic Bight). 

Also, numerous studies have shown that wave-generated currents and storm-generated flows 

impact the ridges several times a year. But this must be a very long-term process and may not 

mitigate the loss of a ridge resulting from dredging activities. 

 An important issue is how fast are the ridges moving, which is an indirect way to infer 

how quickly they will be re-created. The following are some comments from the different 

papers on rates of migration and infill: 

1) Ridges migrate fifty meters per year off Sable Island (Hoogendoorn and Dalrymple, 

1986). 

2) Quote from Alabama report Aubrey et al. (2000) – “alternating bands of erosion and 

accretion on the continental shelf east of Main Pass illustrate relatively slow but steady 

reworking of the upper shelf surface as sand ridges migrate to the west.” One dredged 

area refilled at 10,000 cubic meters per year. An even faster rate was reported where silt 

and clay were refilling the dredged area. 

3) Numbers from Duane et al. (1972) - ridge moved 3600 m in 53 years (off Virginia coast); 

ridge moved 76 m during the Ash Wednesday storm of 1962 (off Delaware). 

These numbers seem to indicate that re-creation or recovery is a possibility in some areas. 

The part of the ridge the sediment comes from would also seem to be an issue. It is 

probable that some engineers would prefer to take the coarsest sand from the northwest side of 

the shoal (Mid-Atlantic Bight example). However, this might slow the rate of recovery of the 

ridge to its original shape and position, because it might be shifted further down current because 

of the absence of the coarse lag on the upcurrent side. If the ridge is located in depths >20 m, the 

possibility of reformation is probably quite remote. According to Goff et al. (1999), in depths 

>20 m, “ridges have not continued to grow since transgression has brought them into the 

offshore hydrodynamic regime”. 

7.1.4 Impact of Dredging 

 One of the primary concerns regarding the impact of dredging is whether the removal of 

sand from the shoal will somehow disrupt the process that maintains the shape of the shoals. For 

example, if convergence of waves over the crest is a contributing factor to maintaining the shape 

of the shoals as suggested in Section 7.1.2, there may be a limit where reduction in the crest 

height of the shoal would suppress this process. The concern would be that the shoal might 

deflate or unravel, losing its form with time. 

 At this time the state-of-the-art in modeling these processes is probably insufficient to 

confidently assess the impact. Therefore, the focus of the monitoring protocols for bathymetry is 

to track changes in the shape of the shoal, ridge, or swale features. 
103

7.1.5 Biological Factors 

 In support of this project, a fly-through of the bathymetry and some biological data 

collected by VIMS (2001) for the Maryland/Delaware shoals and presented in GIS was 

developed. Based on the fly-through, there appeared to be relationships between the topography 

of the shoals, sediment grain size composition, and some of the biological parameters 

characterizing the benthic and nekton communities. It was initially assumed by the project team 

and later confirmed by the fly through that these offshore ridge and shoal features represent very 

diverse and active physical systems with differing habitat conditions located throughout each 

feature. For example, the ridge tops represent a very high wave energy, intensely stirred and 

mixed coarse sediment with low organic material type habitat, whereas the trailing slope of the 

feature (up wave) is a habitat with a very gentle slope, decreasing energy and surface sediment 

mixing from wave action as it slopes into deeper water, and organically enriched sediments from 

deposition of fines. There are at least two other unique physical habitat areas on and surrounding 

the ridge features: 1) the leading (down wave) side of the ridge is steeper and is depositional in 

nature (many ridges will be slowly migrating in the direction of this side of the ridge); and 2) 

deep troughs between the ridges that are relatively sheltered from wave action (due to both depth 

and breaking of waves over the crest of the ridge) and feature fine muddy sediments. The 

benthic communities and fish populations associated with each of these habitats are very 

different, as indicated in the VIMS (2001) study. It can also be assumed that small microhabitats will also exist within the shoal and ridge features. It may be inferred that if a shoal did 

deflate due to dredging impacts, these community structures would be significantly influenced. 

 Despite the prevalence of these features along the east coast of the United States, little is 

documented about the ecological relationships of these features and their associated biological 

communities. Several authors (Louis Berger Group, 1999; Hammer, 1993; Oakwood 

Environmental, 1998) speculate about the importance of offshore ridge and shoal features to 

fisheries migrations and as important habitat for fisheries growth and development. However, a 

literature review conducted by the project team failed to obtain any scientific evidence to support 

these relationships. 

7.1.6 Summary 

 There is no apparent consensus on the processes that work to maintain the shape of the 

ridge, swale, and shoal structures that represent the form of many of the identified OSC borrow 

sites. The role of wave action appears to have been entirely neglected in the literature. While 

there are no direct references in the literature, there is evidence that the form of these sand body 

features may have an important influence on the structure and distribution of biological 

communities inhabiting them. Monitoring for changes to the form of the shoal, grain-size 

characteristics, and the related biological communities is essential. 

 It is also recommended that research into the physical, biological and biophysical 

processes of these features be performed. Results from the monitoring program will be valuable 

for such investigations. 
104

8.0 DATA MANAGEMENT 

 The various monitoring protocols that have been developed and are described in Section 

4 each include a section on requirements for data deliverables. Each monitoring survey 

(triggered by a dredging event or a timing requirement) will result in the collection of large 

amounts of spatial data, most of which will be repeated in subsequent monitoring programs. 

These large data sets will be developed for each borrow deposit or regional group of borrow 

deposits. Over time, this temporal continuance will create an extremely large database of 

information that must be properly organized and documented with appropriate metadata. 

 For each sand borrow site, it will be necessary in the assessment of possible impacts to 

make inter-comparisons between different data layers for a given time period and over time. It is 

likely that these types of analysis will also reveal new understanding on the temporal and spatial 

relationships among the various key physical and biological parameters. As explained in Section 

5.0, understanding these new relationships forms the cornerstone of Adaptive Management, 

guiding future refinements to the monitoring program. 

 A list of generic data types that will be collected is provided in Table 8.1. In addition to 

these parameters that are measured, many other parameters will be derived from this 

information. Some derived data set examples are provided. 

Table 8.1. Data sets to be collected in the OCS sand dredging monitoring program. 

Protocol Data Set Created Derived Data Sets 

Bathymetry 

and Substrate 

Digital Elevation Model of the Seabed, 

Seabed Texture 

Maps of Seabed Change and 

Changes to Bedforms 

Waves Deepwater Wave Record, Wave Climate 

(Height, Period, Direction and spectral 

characteristics) in Offshore, Borrow and 

Nearshore Regions 

Bed Shear Stresses, Sediment 

Mobility Characteristics 

Shoreline Aerial Photos, Nearshore Profiles, Measured 

(interpreted) and Predicted Shoreline 

Positions 

Rates of Shoreline Change, 

Longshore Sand Transport 

Rates 

Benthos Species Presence, Species Abundance, Wet 

Weight and Dry Weight Measurement for 

Each Species 

Species Density, Biomass, 

Secondary Productivity 

Fish Specimen Species Identification, Standard 

Length, Sex and Sexual Maturity, Wet 

Weight of Gut Contents by Taxon, 

Specimen Wet Weight 

Species Abundance, Species 

Density, Species Biomass, 

Index of Relative Importance 

for Gut Contents 

Grain Size % Sand, Silt and Clay per Sample Strata Characteristics, Combine 

with Seabed Texture from 

Bathymetry and Substrate 

Protocol 

Stable 

Isotopes 

Carbon and Nitrogen Isotope Values per 

strata for Benthos and Fish 

Carbon and Nitrogen Isotope 

Ratios. 
105

 Therefore, it is evident that a well-planned data management program will be required. 

The program should achieve the following objectives: 

• Retain the integrity of the original data quality (once collected it cannot be altered); 

• Support easy and timely database update with newly collected data; 

• Adhere to FGDC Metadata standards to permanently document data characteristics (date 

collected, data collection techniques, notes on limitations, etc.); 

• Store data in common horizontal projection and vertical reference datum in GIS format; 

• Be well organized under Protocol groupings and for individual borrow deposits or 

geographic groupings of deposits; 

• Be searchable via keywords and map-based spatial queries; 

• Be fully and easily accessible over the Internet with on-line mapping tools available to 

view the data in a variety of combinations; 

• Be scalable to allow for an ever increasing growth in database size; 

• Provide data download capability based on user access privileges; and 

• Be adaptable to incorporate new or different data types as a result of refinements to the 

monitoring program. 

 In doing so, the data management program will provide the following benefits: 

• The data will be widely used to assess possible impacts and support research into 

improved understanding of the physical, biological and biophysical processes associated 

with the borrow deposit environments; 

• Efficient access to data will maximize the time available to interpret the data; 

• Decision-making processes on impacts will be transparent; and 

• Ensure timely access to information critical to the ongoing Adaptive Management 

program. 
106

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A-1

Appendix A
A-2

WORKSHOP SUMMARY 

Design of a Monitoring Protocol/Plan for Environmentally Sound Management and 

Development of Federal Offshore Borrow Areas Along the United States East and Gulf of 

Mexico Coasts 

In April 2000, the MMS awarded a contract to Research Planning, Inc. (RPI) of 

Columbia, South Carolina to design and develop biological and physical monitoring 

templates for the Outer Continental Shelf (OCS) sand resources. Baird and Associates, 

Inc. and Applied Marine Science are key sub-contractors on the project. The project 

consists of the following components: 

- Development of field monitoring systems to evaluate the physical and biological 

effects of using Federal offshore borrow areas on a long-term basis; 

- Examination of the feasibility, appropriateness, and desirability of putting these 

monitoring systems into place and identification of the need for collection of 

supplemental biological data or physical modeling information in the Federal 

borrow areas; 

- Identification, review, and evaluation of environmental work or mechanisms 

(organizational, economic) that may be needed to offset any potential adverse 

impacts; and 

- Identification of the need for and collection of any additional geological/geophysical data to define available sand supplies for planned projects within the 

study areas. 

An additional component of the project is to formulate options and recommendations 

for including Federal, State, and local governments in an overall planning process to 

manage the Federal offshore borrow sites in an environmentally responsible and costeffective manner over a long-term period. 

A workshop was held on 12 December at the Virginia Institute of Marine Science. The 

objective of the workshop was to have scientific review of the proposed monitoring 

protocols before preparation of the draft report. The workshop agenda and participants 

are listed below. 

Agenda 

8:30 Introductions of Participants 

8:45 Overview of the Project 

9:00 Characteristics of Known Federal OCS Borrow Sites 

10:00 Monitoring Questions to be Addressed 

10:30 Impacts Summary and Monitoring Objectives 

11:00 Proposed Monitoring Approaches 

12:00 Lunch 

13:30 Open Discussion 
A-3

16:30 Summary of Discussion, Future Directions 

17:00 Adjourn 

List of Participants 

USACE 

Joan Pope, Corps of Engineers Coastal and Hydraulics Lab 

Jerry Swean, Norfolk District 

Chris Spaur, Baltimore District 

VIMS 

Woody Hobbs, Bob Diaz, Scott Hardaway, Jerome Maa, Lyle Varnell 

David Basco, Old Dominion 

Bob Van Dolah, S.C. Department of Natural Resources 

Jeff Redidenauer, Louis Berger & Associates 

Rich Hammer , Continental Shelf Associates 

Mark Byrnes, Applied Coastal Research and Engineering, Inc. 

Barry Vittor, Barry Vittor & Associates, Inc. 

MMS 

Barry Drucker, Beth Burkhard 

Project Quality Review Board 

 Al Hine, University of South Florida 

 Stan Riggs, East Carolina University 

Project Team 

 Jacqueline Michel, Research Planning, Inc. 

 Rob Nairn, Baird & Associates Ltd 

 Jay Johnson and Dane Hardin, Applied Marine Sciences, Inc. 
A-4

Regional Sand Management Strategy Issues from the 12 December 2000 Workshop 

1. Identify critical endpoints, e.g., 

- maximum removal depths or volumes 

- no pits (and definition of pit) 

- don’t affect shape 

- don’t affect wave patterns that lead to shoreline erosion/change 

- don’t affect grain size that will affect future utility of the site prematurely 

2. Talk with Bob Dean about CETAC guidelines for Florida 

3. Consider sand transport processes, whole system functioning, in coordination with the ACOE 

4. Fish issues to deal with: Essential fish habitat, fish utilization of topographic features for 

migration, spawning/juvenile habitat. Look at coming report by Diaz on fish probability 

model; check with fishers about local knowledge 

5. Data gap: how to dredge shoals to maximize their use? 

6. Funding for long-term monitoring from the lessee? Need justification; show that it is in their 

best long-term interest; that they will get better use of sites. 

7. Shoreline change monitoring guidelines. Check with MD, DE, FL for programmatic 

guidelines. 

8. Develop the concept of a Technical Review Committee at the regional level. Would have 

ability to review and change monitoring programs, using the Adaptive Management 

Approach. Determine resource utilization timeframes (volume available versus long-term 

needs) that would filter into monitoring plans. 

9. The concept of a national Science Review Committee that would: 

- deal with multi-site issues, 

- develop nation-wide guidelines, 

- determine conformance of monitoring programs with the guidelines, 

- approve changes to monitoring programs recommended by the regional groups 

- be totally independent of work being done at the sites 

10. Define levels of change in parameters that are acceptable. e.g., 80% of volume lost has been 

replaced, biological abundance/diversity to xx% of reference, etc. 

11. Find out what chemical testing of borrow site materials is already being done by both the 

ACOE and by states working on projects without ACOE funding (e.g., Florida). 
A-5

Monitoring Protocol Issues from the 12 December 2000 Workshop 

1. Make sure that all sand deposit categories are considered, Emphasis is currently on shoals, 

ridges and swales, because they are the primary targets. 

2. Physical Impacts - add change in grain size that affects the future utility of the sites (where it 

might fill with mud and become unsuitable for re-use). 

3. Data Gaps: 

- definition of pit, dimensions (use ACOE max side slopes, SCDNR example) 

- fish utilization of topographic features 

- where on ridges is it best to dredge 

4. How to deal with the shoreline change issues? Rob Nairn to write up draft guidelines. May 

be two types of analysis: 1) at the placement site, and 2) associated with the borrow site. 

5. Ecological succession model - applicability to shelf benthic invertebrates? We decided it 

was not and would remove references to it. 

6. Physical monitoring ideas: 

- "recovery of volume lost" per Van Dolah 

- bathymetry - specify number of points 

- how to consider the passage of a major storm in the monitoring plan 

- to increase understanding of natural variability in physical parameters, check into the USGS 

bathymetry work; do not expand size of the monitoring 

- specify criteria versus technology, but suggest current technology that meets criteria 

- develop a grain size protocol 

- re-run the wave models for real post-dredging bathymetry 

- discuss requirements for deep water wave climate data and need for a buoy 

- plume monitoring requirements will be delayed until the results of the new study being 

conducted by MMS are available. 

7. Be very clear about what need for specific data, to justify monitoring costs. 

8. Biological monitoring: 

- for marine mammals and turtles during operations, refer to the NMFS trained observer 

guidelines; but do write protocols for increased stranding component 

- Fish protocols need more development; talk with Ken Able about juvenile fish issues. 

- benthos: yes, specify gear for grab sampler. 

- for benthos, generate a list of appropriate parameters for spatial and temporal comparisons, s 

- for determining number of sites to sample for benthos, use random/stratified design but need 

guidance on degree of uncertainty allowed, definition of strata, guidance on the minimum 

number of samples per strata, guidance on how they can modify density over time. AMS to 

consult with biostatistician on these issues 

- need definition of recovery, along the lines that were presented 

- we do not need chemical pollutant analyses; do not need archive sample splits