Biological impacts of minor shoreline structures on the coastal environment state of the art review

[From the U.S. Government Printing Office, www.gpo.gov]

Biological Services Program

FWS/OBS-77/51
Mirch 1980
Biological Impacts of Minor Shoreline
Structures on the Coastal Environment:
State of the Art Review
-VOLUME I

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'ish and Wildlife Service
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1980
V. 1

The Biological Services Program was established within the U.S. Fish
and Wildlife Service to supply scientific information and methodologies on
key environmental issues that impact fish and wildlife resources and their
supporting ecosystems. The mission of the program is as follows:

* To strengthen the Fish and Wildlife Service in its role as
a primary source of information on national fish and wild-
life resources, particularly in respect to environmental
impact assessment.

s To gather, analyze, and present information that will aid
decisionmakers in the identification and resolution of
problems associated with major changes in land and water
use.

# To provide better ecological information and evaluation
for Department of the Interior development programs, such
as those relating to energy development.

Information developed by the Biological Services Program is intended
for use in the planning and decisionmaking process to prevent or minimize
the impact of development on fish and wildlife. Research activities and
technical assistance services are based on an analysis of the issues a
determination of the decisionmakers involved and their information needs,
and an evaluation of the state of the art to identify information gaps
and to determine priorities. This is a strategy that will ensure that
the products produced and disseminated are timely and useful.

Projects have been initiated in the following areas: coal extraction
and conversion; power plantsi geothermal, mineral and oil shale develop-
ment; water resource analysis, including stream alterations and western
water allocation; coastal ecosystems and Outer Continental Shelf develop-
ment; and systems inventory, including National Wetland Inventory,
habitat classification and analysis, and information transfer.

The Biological Services Program consists of the Office of Biological
Services in Washington, D.C., which is responsible for overall planning and
management; National Teams, which provide the Program's central scientific
and technical expertise and arrange for contracting biological services
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Staff, who provide a link to problems at the operating level; and staff at
certain Fish and Wildlife Service research facilities, who conduct inhouse
research studies.

FWS/OBS-77/51
March 1980

BIOLOGICAL IMPACTS OF MINOR SHORELINE
STRUCTURES ON THE COASTAL ENVIRONMENT:
STATE OF THE ART REVIEW

VOLUME I

E. L. Mulvihill, C. A. Francisco, J. B. Glad,
K. B. Kaster, and R. E. Wilson

Beak Consultants, Inc.
317 S.W. Alder
Portland, Oregon 97204

with

0. Beeman - Special Consultant

Project Officer
Larry R. Shanks
National Coastal Ecosystems Team
U.S. Fish and Wildlife Service
NASA-Slidell Computer Complex
1010 Gause Boulevard
Slidell, Louisiana 70458

Prepared for

National Coastal Ecosystems Team
Office of Biological Services
Fish and Wildlife Service
U.S. Department of the Interior
Washington, D.C. 20240

For sale by the Superintendent of Documents, U.S. Government Printing office, Washington, D.C. 20402
US Department of Commerce
NOAA Coastal Services Center Library
2234 South Hobson Avenue
Charleston, SC 29405-2413

PREFACE

This report was written for fish and wildlife biologists who review
permits for the construction of minor shoreline structures in the coastal
environment, and was submitted in fullfillment of Contract 14-16-0008-2153.

Any suggestions or questions regarding this review should be directed to:

Information Specialist
National Coastal Ecosystems Team
U.S. Fish and Wildlife Service
NASA-Slidell Computer Complex
1010 Gause Boulevard
Slidell, Louisiana 70458

The correct citation for this report is:

Mulvihill, E. L., C. A. Francisco, J. B. Glad, K. B. Kaster, and
R. E. Wilson. 1980. Biological impacts of minor shoreline structures
on the coastal environment: state of the art review. U.S. Fish and
Wildlife Service, Biological Services Program. FWS/OBS-77/51. 2 vol.

iii

SUMMARY

Beak Consultants Incorporated conducted a state of the art review of the
biological impacts of minor shoreline structures on the coastal environment.
The types of structures included in this study were as follows: breakwaters,
jetties, groins, bulkheads, revetments, ramps, piers and other support struc-
tures, buoys and floating platforms, harbors for small craft, bridges and
causeways.

A total of 555 information sources were obtained at which approximately
220 references were found by commercial bibliographic searches. Other sources
were located by cross referencing from identified sources; visiting key li-
braries; interviewing and sending questionnaires to institutions, government
agencies, and individuals who might have had useful information.

Information was extracted from the literature and compiled by type of
shoreline structure and by coastal region. The following categories of infor-
mation were sought: structure functions; site characteristics; geographic
prevalence; engineering, socioeconomic and biological placement constraints;
construction materials; expected life span; environmental conditions; method-
ology of environmental impact studies; physical and biological impacts; and
structural and nonstructural alternatives.

Existing information was evaluated and a text was prepared (Volume I).
An annotated bibliography, keyword index and primary author reference number
index were produced from the data base (V@lume II).

This state of the art review summarizes and evaluates the information
found in the literature for each type of structure. Areas requiring additional
study are delineated. Germane studies in progress are identified, and selected
case histories depicting the impacts of shoreline structures are presented as
part of the review.

The impact of any structure on the coastal environment is site-specific
and should be considered on a case-by-case basis. Few studies were found
which quantitatively investigated the impacts of specific structures.

Structures which appear to have the greatest potential for impacting the
coastal environment are small boat harbors, bridges and causeways, bulkheads,
breakwaters, and jetties. Those with moderate impact potential are revetments,
groins, and ramps. Low-impact potential structures include buoys and floating
platforms, and piers, pilings and other support structures. Based on this
classification scheme and the number and types of information sources located,
bridges, causeways, and small boat harbords have received very little study
relative to their potential impacts.

CONTENTS

Page
PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . vii

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
METHODS OF INVESTIGATION . . . . . . . . . . . . . . . . . . . . . 5
SUMMARY OF LITERATURE . . . . . . . . . . . . . . . . . . . . . . . 10
Breakwaters . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Jetties . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Groins . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Bulkheads . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Revetments . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Ramps . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Piers, Pilings and Other Support Structures . . . . . . . . . 78
Buoys and Floating Platforms . . . . . . . . . . . . . . . . . 90
Harbors for Small Craft . . . . . . . . . . . . . . . . . . . 91
Bridges and Causeways . . . . . . . . . . . . . . . . . . . . 99
CASE HISTORY STUDIES . . . . . . . . . . . . . . . . 107
Case History - Small Craft Harbors In Coastal Region 1 -
North Pacific . . . . . 107
Case History - Jetty In Coastal Region 1 - North Pacific . . . 109
Case History - Bulkheads In Coastal Region 2 - Southern
California . . . . . . . . . . 112
Case History - Small Craft Harbors In Coastal Region 2
Southern California 113
Case History - Bulkheads In Coastal Region 3 Gulf of
Mexico . . 114
Case History - Causeways In Coastal Region 3 Gulf of
Mexico . . . 115
Case History - Bridges and Causeways In Coastal Region 4
South Florida . . . . 117
Case History - Groins In Coastal Region 5 - South Atlantic 122
Case History - Bulkheads In Coastal Region 6 - Middle
Atlantic . . . . . . . . . . . . . . . . 123
Case History - Sandbag Sill Breakwaters In Coastal Region 6
Middle Atlantic . . . . . . . . . . . . . 124
Case History - Piers, Pilings and Other Support Structures
In Coastal Region 7 - North Atlantic . . . . . . . . . . 125
Case History - Jetties in Coastal Region 7 - North Atlantic. 126
Case History - Bulkheads and Associated Dredging In Coastal
Region 8 - Great Lakes . . . . . . . . . . . . . . . . . 127
Case History - Groins In Coastal Region 8 Great Lakes . . . 128
RESEARCH IN PROGRESS 134
ENVIRONMENTAL IMPACT ASSESSMENT METHODOLOGY . . . . . . . . . . . . 135
EVALUATION OF EXISTING DATA . . . . . . . . . . . . . . . . . . . . 137
RESEARCH NEEDS . . . . . . . . . . . . . . . . . . . . . . . . . . 141
GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

FIGURES

Figure Pace

1 Coastal regions as defined in the text . . . . . . . . . . . . 2
2 Flow chart of the methods of investigation . . . . . . . . . . 6
3 Locations where questionnaires were sent and personal -inter-
views conducted . . . . . . . . . . . . . . . . . . . . . . . 7
4 Shoreline structures data base - System 2000 . . . . . . . . . 8
5 A small naturally protected harbor at Port Orford, Ore,
gon is
provided waved protection by a connected dogleg breakwater
6 Protection for the Shilshole Marina is afforded by the off-
shore breakwater . . . . . . . . . . . . . . . . . . . . . . . 12
7 A floating breakwater shelters a marina in Yaquina Bay,
Oregon . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8 Cross-sectional view of typical submerged and emergent rubble-
mound breakwaters . . . . . . . . . . . . . . . . . . . . . . 15
9 This unconventional zig-zag breakwater design has performed
well and has stopped further erosion of the bluff at this
site . . . . . . . . . . . . . . . . . i * * ' ' * i * ' * * * 16
10 Cross-sectional view of a tethered floating breakwater . . . . 17
11 Tribar, a precast, reinforced concrete structure used as fac-
ing on breakwaters and jetties . . . . . . . . . . . . . . . . 21
12 The dotted lines show typical areas of erosion and sand
accumulation behind attached doglet and detached solid
breakwaters . . 23
13 Jetties at mouth WCo*qu'il'le* R*iv*e@,-Ba-nd-on-,-Or-eg-on- . . . . . . 27
14 Dolosses are being installed as protective facing on this
rubble mound jetty in Humboldt Bay, California . . . . . . . . 30
15 Concrete groins at the base of a revetment on the Gulf coast
of Florida . . . . . . . . . . . . . . . . . . . . . . . . . . 35
16 Timber pile groins, Puget Sound, Washington . . . . . . . . . 36
17 Rubble mound groin in the southeastern United States . . . . . 37
18 Gabions are used to construct groins on the Great Lakes . . . . 39
19 Side view of an impermeable groin . . . . . . . . . . . . . . 40
20 Prefabricated permeable groin . . . . . . . . . . . . . . . . 41
21 Waves breaking against the concrete bulkhead bordering the
causeway in Apalachicola Bay, Florida . . . . . . . . . . . . 46
22 Wooden sheet pile bulkhead at low tide . . . . . . . . . . . . 47
23 Concrete seawall in Florida . . . . . . * ' * * ' ' * * * * * 50
24 Concrete bulkhead on Fidalgo Island, Washington . . . . . . . 50
25 Bulkhead constructed of a series of wood piles . . . . . . . . 51
26 Wooden sheet pile bulkhead along the Gulf coast of Florida . . 51
27 Side view of a typical sheet pile bulkhead . . . . . . . . . . 52
28 Old bulkhead line on a beach that has continued to erode in
Skunk Bay, Washington . . . . . . . . . . . . . . . . . . . . 54
29 This riprap revetment functions to limit erosion of the park-
ing lot at the Kingston, Washington ferry terminal . . . . . . 59
30 Riprap revetment protects the U.S. Coast Guard Light Station
at Point No Point, Washington . . . . . . . . . . . . . . . . 60
31 Concrete revetment along U.S. Highway 98 in the vicinity of
Port St. Joe, Florida . . . . . . . . . . . . . . . . . . . . 61

Figure 2Age

32 Failure of this interlocking concrete block revetment was
primarily due to settling and erosion of supporting beach
material . . . . . . . . * . I * * * . . . . . . . . . . . 63
33 Pictured is a junk car revetment in Florida . . . . . . . . . 65
34 Profile of a revetment . . . . . . * * ' ' * * * " * ' * * * * 67
35 A Nami Ring revetment was constructed in 1974 at Little
Girls Point on Lake Superior as part of the Michigan State
Demonstration Erosion Control Program . . . . . . . . . . . . 69
36 An interlocking concrete block revetment forms a checkerboard
pattern on the shoreline . . . . . . . . . . . . . . . . . . . 69
37 An elaborate launching ramp in Coos Bay, Oregon . . . . . . . 75
38 A simple launching ramp in the vicinity of Panama City,
Florida . . . . . . . . * . * * ' * * * ' * ' * ' ' * * ' 76
39 Marine way at Point No Point beach resort in Puget Sound,
Washington . . . . . . . . . . . . . . . . . . . . . . . . . . 79
40 Floating pier at Kingston Marina, Kingston, Washington . . . . 81
41 Piling in Key West, Florida supports navigational aids . . . . 82
42 Open-pile pier near Hansville, Washington . . . . * * * * * * 83
43 Gribble damage to a mooring dolphin in Key West, Florida can
be seen near the water level . . . : * * I * * * I * I * I * * 84
44 Cross-sectional view of a typical pier . . . . . . . . . . . . 86
45 Submerged structures offer substrate for the attachment of
various types of marine organisms . . . . . . . . . . . . . . 89
46 Crescent City, California inner boat basin . . . . . . . . . . 93
47 Winchester Bay, Oregon . . . . . . . . . . . . . . . . . . . . 94
48 Charleston Harbor, Oregon . . . . . . . . . . . . . . . . . . 95
49 Many of the older bridges (top, center) along the Overseas
Highway to Key West, Florida, are being replaced by new
structures (bottom) . . . . . . . . . . . . . * * . . . . . 100
50 A bridge and causeway system crosses Apalachicola B@y on
the Gulf coast of Florida . . . . . . . . . . . . . . . . . . 101
51 A silt curtain is used to contain sediment produced by
causeway work on the Overseas Highway in Florida . . . . . . . 102
52 The Roberts Bank Causeway in British Columbia effectively
diverts Fraser River silt laden water away from the
shoreline . . . . . . . . . . . . * ' ' * - - . . . . 105
53 Four different marina designs in Puget Soun@,'Wash*ingtion . . . 1o8
54 Tillamook jetties, Tillamook Bay, Oregon . . . . . . . . . . . 110
55 Cross-sectional view of a causeway constructed with fill
material from a nearby borrow area . . . . . . . . . . . . . . 121
56 A 40-in (1-m) Longard tube groin at Sanilac site . . . . . . . 130
57 Sandbag groin at Sanilac site, showing loss of sandbags at
lake end . . . * 131
58 Gabion groin at S;nila*c*sit@ 132
59 Rock mastic groin at Sanilac site . . . . . . . . . . . . . . 133
60 The number of references by structure category and rating
that contained information relevant to the present study . . . 138
61 The number of references by coastal region and structure
that contained information that was relevant to the present
study . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

vii

ACKNOWLEDGMENTS

Edward L. Mulvihill, Project Manager, provided technical and administra-
tive management of the project. Larry Shanks served as Project Officer for
the National Coastal Ecosystems Team. He was extremely helpful in supplying
liaison with Federal agencies and in securing numerous project related docu-
ments. Daniel H. McKenzie served as Project Manager during the initial phases
of the project. Ogden Beeman, Specia i Consultant, provided engineering input
to the project. Judith B. Glad coordinated reading and literature acquisi-
tion. Carol A. Francisco assisted in reading and report coordination. Ronald
E. Wilson provided all computer support. Sections of the final report were
written by Edward Mulvihill, Ogden Beeman, Carol Francisco, Judith Glad and
Karen Kaster. Reading was done by Carol Francisco, Judith Glad, Karen Ka�ter,.
Phillip Havens, Mark Hill, Ronald Klein and Joan Stevens. Also, a special
thanks is extended to those individuals who provided information on shoreline
structures through interviews and responses to the questionnaire.

viii

I N T R 0 D U C T 10 N

The Fish and Wildlife Coordination Task 3. Information Evaluation: To
Act req uires any p u blic or private analyze the biological impacts of minor
agency proposing activities which would shoreline structures, to identify alter-
control or modify the waters of any natives, to describe germane studies in
stream or body of water to consult with progress and to identify areas of insuf-
the U , S.Fish and Wildlife Service (FWS) ficient research.
with a view to the conservation of
wildlife resources by preventing loss of Each article or data source was
and dama.ge to such resources. .."(U.S. examined within the limits set by the
Dept. of Interior, Fish and Wildlife Ser- following outline
vice 1975b). State and Federal legisla-
tion requires environmental impact as- 0 Structure
sessments prior to construction in the 0 D efi nitio n
coastal zone. 0 Structure functions
0 Site characteristics and
.The U.S. Fish and Wildlife Ser- environmental conditions
vice, charged with reviewing permit ap- 0 Placement constraints
plications for construction in coastal Engineering
zones, must be able to evaluate envi- Socioeconomic
ronmental impacts and suggest function- Biological
ally feasible structural or nonstructural 0 Construction materials
alternatives which could minimize envi- 0 Expected life span
ronmental damage. Before such assess- 0 Unaltered and altered
ments can be made, the initial effects environmental conditions
during structure construction continued 0 Environmental impact
impact due to the presence of a struc- methodology
ture, and cumulative perturbation due 0 Summary of physical and
to a number of existing structures with- biological impacts
in a coastal zone must be known. Thus, Construction effects
it is advantageous to have a usable and Chronic effects
comprehensive compendium of structure- Cumulative effects
related information which is specific to 0 Structural and nonstructural
biogeographic regions. It is the objec- alternatives
tive of this report to summarize the 0 Regional considerations
known ecological impacts of minor shore-
lin e structures and to define those Types of structures included in
areas where lack of quantitative data in the study are
the published literature makes assess-
ment of environmental impacts difficult. 0 B reak waters
0 Jetties
This report is the final product of 0 Groins
a three-phase study. The objectives 0 Bulkheads
were 0 Revetments
0 Ramps
Task 1. Information Search: To de- 0 Piers, pilings, and other support
velop a d tailed study outline, to inte- structures
grate it with FWS objectives, to obtain 0 Buoys and floating platforms
a comprehensive list of references and 0 Harbors for small craft
other sources of information, to secure 0 Bridges and causeways
what is immediately available, and to
outline the effort required to secure the The eight coastal regions selected
other materials. for this study are defined as follows
(Figure 1)
Task 2. Information Transformation:
To review the literature,to extract Coastal Rt@on Geographical
relevant information and to enter the Boundaries
data in a computer data-base. 1. North Pacific Pucet Sound to
Monterey Bay
1

North
Paci f ic
Region 1 Great Lake

Region 8

7--

Point
Pinos

Southern
California

Region 2

Imperial
Beach

Te ra Ceio
Gul f of
100 150 Mexico
EMT-@- MILES
!, 215. 50 150 Region 3
N KILOMETERS Port Isabel

Figure 1 Coastal regions as defined in the text.

2. Southern California Monterey B ay during the study. Structures that have
to San Diego similar components but different func-
B ay tions (e.g. , jetties, breakwaters, and
3. Gulf of Mexico Laguna Madre groins) may, in many cases, have simi-
to Tampa Bay lar biological impacts. For these rea-
4. South Florida Tampa Bay to sons, the entire report should be read
Banana River before attempting to evaluate the impact
5. South Atlantic Banana River of a specific structure.
to Pamlico
Sound The report is written for a profes-
6. Middle Atlantic Pamlico Sound sional biologist with some prior expo-
to Coney sure to shoreline structures. It is in-
Island tended to be useful during biological
7. North Atlantic Coney Island evaluations of applications to construct
to B ay of shoreline structures. The report is not
Fundy intended to be a manual to assist engi-
8. Great Lakes Great Lakes neers in the design of structures.

In addition to information specific The text of this report includes a
to each region, this report contains a summary of the literature (organized by
large body of data that is generally ap- structure type), case history studies
plicable to all coastal regions. Coast- (arranged by coastal region),a summary
lines of Alaska and Hawaii were not in- of research in progress, an assessment
cluded in the study. of current environmental im pact re-
search methodologies and needs, and an
Only structu re- related sources of evaluation of the existing data.
information were sought because the
stated objective of this study was to The text is followed by a glossary.
provide a document that would aid in A keyword index, a primary author re-
assessing environmental impacts of ference number index, and an annotated
shoreline structures. There are num- bibliography is contained in Volume II.
erous sources of information that are Entries in the annotated bibliography
engineering or biologically related that are alphabetized by primary author
were considered to be beyond the scope (first author when an article has mul-
of this study. Examples would be pro- tiple authors). References containing
ductivity of artificial reefs or succes- information about a specific subject o@
sional patterns, species composition,and group of s u biects can be obtained
p rod u ctivity on s u b merged s u rfaces. through the keyword index. The key-
Information on dredging and filling was words for each reference are sorted
included only where the dredging was alphabetically. Each keyword for each
performed to supply fill for construct- reference appears as the first keyword
ing a structure. Backfilling a bulkhead in the keyword index followed by the
would be an example. A comprehensive other keywords for that reference. This
review on the effects of dredging is gives the user access to an article via
contained in Morton (1976). any keyword for that article and also
allows the user to combine keywords to
The report contains a summary of gain access to specific classes of arti-
the published literature and other infor- cles (for example, all articles with the
mation sources. A conscious effort was keywords fish, revetments, and Coastal
made to report only that information Region 1).
from the literature and not to insert the
personal views of the writers of this The primary author reference num-
report. ber index contains the number of the
primary author of each article referred
The evaluation of each structure to by reference number in the keyword
was based on contents of the literature. index. References can then be located
Several structures had a sparse data in the annotated bibliography.
base. A functional approach, rather
than a structural approach, was taken This report provides a perspective

on the state of the art for determining
the biological impacts of minor shorelin@
structures on the coastal environment.
The usefulness of the text for a speci-
fic structure is enhanced if the user
consults other portions of the text for
information about similar types of struc-
tu res. For example, when researching
boat ramps, the user should read the
revetment section in a d ditio n to the
ramp section. The section on piers,
pilings, and support structures also
should be consulted if a dock is to be
constructed as part of the boat ramp
facility.

The text of this report does not
reproduce all of the detail contained in
the literature. For this reason, the
user should refer to the source docu-
ments when evaluating a specific type
of structure, as well as the annotated
bi blio g ra p hy contained in Volume II.

METHODS OF INVESTIGATION

The methods of investigation used pertinent citation information, keywords,
in this study are depicted in Figure 2. and a rating. Articles were rated ac-
Before the information search began, cording to their applicability and useful-
goals were established and a conceptual ness to the objectives of the project
outline was created. A Procedures Man- (not for their scientific excellence or
ual was prepared which contained steps validity) on a scale of one (excellent)
fo r i n fo rm atio nextraction and data to five (poor). Those articles that were
sheet completion, as well as a conceptu- reviewed , but not considered directly
al outline of the project. Readers were applicable to the objectives of the study
subsequently trained, using the Proce- were abstracted, but not keyworded.
dures Manual, and their ability to ex-
tract relevant information was tested. The two types of data sheets were
reviewed for punctuation and spelling
Concurrent with the training pro- before being sent to keypunch. After
cedure, the search for information was keypunching, the data were again
begun using commercial search services, checked for punctuation, spelling, con-
primarily through the Oceanic and At- tents, and keypunching errors. The
mospheric Scientific Information System data were then entered into the data
(OASIS). This system is quite inclu- base (Figure 4).
sive of the commercial data bases that
may contain information regarding minor The data base management system
shoreline structures. A p proximately used by Beak Consultants Incorporated
220 of the 555 total information sources was System 2000 developed by MRI
were found using the OASIS search. Systems Corporation of Austin, Texas.
The balance of the information sources This system was made available through
came from bibliographies contained in Computer Sciences Corporation's (CSC)
identified sources, questionnaires, lib- INFONET timesharing system on the
raries, and interviews. UNIVAC 1108 computer. In addition to
System 2000, Beak Consultants Incorpo-
A p proximately 300 questionnaires rated used its own proprietary FOR-
were distributed to institutions, govern- TRAN programs to load the data base
ment agencies, and individuals that and provide the formatted outputs.
might have releva nt information. A System 2000 was used because of its
conceptual outline of the project accom- ability to handle the large amount of
panied the questionnaires. Nonrespond- data that were extracted from the infor-
ents and those respondents whose an- mation sources and also because of the
swers needed clarification were contact- multilevel on-line access ca p a bility
ed by telephone. Where desirable,inter- which provided assistance during the
views and/or telephone calls were made report writing phase.
with persons supplying valuable infor-
rr..ation in the questionnaire responses. The outputs produced from the
Approximately 40 interviews were con- data base were an annotated bibliogra-
ducted. The map in Figure 3 shows the phy, keyword index, primary author
areas of the United States where ques- reference number index, and a printout
tionnaires were sent and where inter- of information extracted. The informa-
views were conducted. Materials were tion was printed in a Region-Structure
accepted and entered into the data base hierarchy although System 2000 has the
until the eighth month, at which time capability of supplying a printout in
searching was halted to facilitate timely numerous hierarchies. Data base inter-
completion of the contract report. In- rogation during report writing was done
formation was extracted from the litera- through various data base entry points.
ture and entered on data sheets by Using the data outputs the existing in-
structure type and region. The informa- formation was evaluated and interpret-
tion categories are contained in Figure ed. A text was written according to
4. A bibliographic data sheet was also the structure types and information cat-
completed for each source. That sheet egories presented previously in this
contained title, author, abstract, other section. An evaluation of the existing

Procedures
Manual

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o Edit

Data Base
See Figure 3

0
4-) A not Structure Dat ractive Keywo d [rLImary Author
to jInte F
Bibliog Printout Inquiry rnde NZeference
imber Index
>

erpr etation a
v
4-) 7Ealuation of
to fo
E In rmati,on
S-
o
4-
Final Report
ol r

Figure 2. Flow chart of the methods of investigation.

100 W
MILES
2-5 50 150 KILOMETERS
N

Figure 3. Locations where questionnaires were sent and personal interviews conducted.
Locations receiving letters and questionnairps
Locations of personal interviews

REFERENCE NUMBER
REFERENCE TYPE
ORIENTATION
REFERENCE DATE
TITLE OF ARTICLE OR TOPIC
ADDITIONAL BIBLIOGRAPHIC
INFORMATION
RATINr
FIRST AUTHOR

r
AUTHOR KEYWORDS ABSTRACT STRUCTURE
AUTHOR NAME KEYWORDS ABSTRACT TEXT REFERENCE NUMBER
RATING
STRUCTURE NAME
LOCAL NAME
FUNCTION
MATERIAL
PLANS AVAILABLE
COASTAL REGION
TOWN-STATE
WATERWAY
LIFESPAN
00 ALTERNATE LOCATION
ALTERNATE STRUCTURE
PREVALENCE IN REGION
METHOD OF EIA
DESCRIPTION OF RESEARCH

SITE PLACEMFNT UNALTERED ENVIRONMENT ALTERED ENVIRONMENT
PLACEMENT RELATIVE TO CONSTRAINTS GENERAL CHA'RACTERISTICS GENERAL CHARACTERISTICS
SHORELINE ENGINEERINn SHORELINE TOPOGRAPHY SHORELINE TOPOGRAPHY
ELEVATION/DEPTH SOCIOECONOMrr SUBSTRATE SUBSTRATE
TIDAL ZONES BIOLOGICAL ENVIRONMENTAL FACTnRS ENVIRONMENTAL FACTORS
OTHERS FLORA FLORA
I VERTEBRATE FAUNA VERTEBRATE FAUNA
INVERTEBRATE FAUNA INVERTEBRATE FAUNA
ECnLOGICAL RELATIOMSHfPS ECOLOGICAL RELATIONSHIPS
OTHERS SHORT TERM PHYS. IMPACTS
SHORT TERM BID. IMPACTS
LONG TERM PHYS. IMPACT
LONG TERM BID. IMPACTS
OTHERS
@TRUCTUP E
FERE CE NUV
:1 @@M ___ N

Figure 4. Shoreline structures data base System 2000.

data base for each structure type was
made based on the number of available
references and their ratings. Germane
studies in progress were identified and
the potential contribution to the state of
the art projected.

Case histories of the impact of the
shoreline structures were also prepar-
ed. Wherever possible, the case history
included information about the biological
and physical environment before and
after construction of the structure, an
evaluation 6f, the effectiveness of the
structu'@e, 'and a-h evaluation of the im-
pacts of the structure on the physical
environme'rif and on -fish and wildlife
habitat.

The text (Volume 1), the primary
author reference number index, the
keyword index, and the annotated bibli-
ography (Volume 2) comprise the final
report.

SUMMARY OF LITERATURE

BREAKWATERS waters of a harbor or adiacent area.

D efi nitio n Detached breakwaters may be used to
prevent or reduce wave penetration into
A breakwater is a structure offer- a harbor entrance or to reduce the wave
ing wave protection to a shore harbor, attack on a costly structure, such as a
anchorage, or basin. Breakwaters are seawall or a power plant. Detached
usually "constructed to create calm wa- breakwaters may also be used as sand
ter in a harbor area, and provide pro- traps due to the tendency of sand to ac-
tection for safe mooring, operating and crete on the beach in the lee of the
handling of ships, and protection for breakwater.
harbor facilities" (U.S. Army Corps of
Engineers 1973b). Site Characteristics and Environmental
Conditions
B reak waters may be further defin-
ed as fixed or floating, and shore-con- Shore-connected breakwaters often
nected or detached. Fixed breakwaters have the connected end lying perpendic-
are built up from. the ocean, lake, or ular to the shoreline and the free end
estuarine floor while floatino breakwa- lying parallel to the shoreline (Figure
ters float at or near the water surface 5). In most cases, detached, or off-
and are held in place by a system of shore, breakwaters are parallel to the
tethers and anchors. Shore-connected shore (Figure 6). Shore-connected break-
breakwaters have a connection to exist- waters are placed according to site-spe-
ing land while detached breakwaters are cific functional requirements. Breakwa-
not connected to the land. A detached ters are most commonly Used to provide a
breakwater might also be called a paral- sheltered harbor and, consequently, are
lel or offshore breakwater. Shore-con- placed where they create an area with
nected breakwaters are structurally sim- minimum wave and surge action (U.S. Army
ilar to jetties, but differ in function in Corps of Engineers 1973b). When asso-
that their primary purpose is to reduce ciated with harbors and marinas, break-
wave energy, not to maintain water waters usually define boundaries and
depth. Some structures fu n ctio n as provide navigation channels, as well as
breakwaters and jetties. enclosing areas of lowered wave energy.
Because their primary function is energy
Figure 5 is a photograph of a con- dissipation, breakwaters are usually
nected coastal break water which was placed in high-energy environments, such
constructed to offer protection for a as coastal areas, semienclosed, or en-
natural harbor. Figure 6 is a photo- closed bodies of water where there is a
graph of an offshore breakwater which long fetch or high occurrence of vessel-
was constructed to create a harbor. generated waves. In at least one case,
Figure 7 contains an example of a float- however, breakwaters contributed to wave
ing breakwater. resonance and caused considerable surge
within the harbor, resulting in boat
Structure Functions damage (Slawson 1977). Breakwater place-
ment is often determined by the exist-
Probably the best known use of ence of a shoreline area suitable for
breakwaters is to create or enhance harbor facilities rather than by bottom
harbors for large or small craft. Nor- topography, littoral processes, or other
mally these shore-connected breakwaters factors.
extend into a body of water to provide
protection from waves caused by either The biota of breakwater sites has
wind or passing vessels. Break waters apparently had little study. No general-
constructed to create a harbor may ad- izations can be made, based on existing
ditionally protect the shoreline from data, concerning bottom characteristics,
erosion, alter longshore sediment trans- water quality, flora and fauna, or eco-
port, and support pedestrian or vehicu- logical interrelationships at locations
lar traffic requiring access to deeper where breakwaters have been planned or

,, A@4

4 4A

41Y

Figure 5. A small naturally protected harbor at Port Orford, Oregon is provided wave
protection by a connected dogleg breakwater. Photograph courtesy of the U.S. Army
Engineer District, Portland, Oregon.

001,

..Am jh. J6-

Figure 6 Protection for the Shilshole Marina is afforded by the offshore breakwater.
The marina was designed to allow good flushing. An attached dogleg breakwater is
visible in the upper left corner of the photograph. Photograph courtesy of the
Washington State Department of Fisheries.

N .. MML4

Figure 7. A floating breakwater shelters a marina in Yaquina Bay, Oregon. A
navigation channel exists between the floating breakwater and the timber pile
breakwater. Photograph courtesy of CH2M Hill, Inc.

constructed. Communities which occur facing material, face slope, structure
on breakwaters are those characteristic height, water depth, and wave climate at
of intertidal and subtidal rocky shores. the-site. A breakwater Must be designed
The exposed side is often characterized and constructed to allow breaking waves
by communities adapted to high-energy to expend their energy over a large area
environments while the back side is rather than a single point (Coen-Cagli
generally inhabited by organisms typical 1932). The outer slope of a breakwater
of less hostile environments. should be a low angle. The crest should
reach a height which either prevents
Placement Constraints overtopping by the design wave or allows
only a preplanned amount of overtopping.
Enqineering. Breakwater design The design should also include provi-
must consider the physical environment sions to prevent piling LIP of water be-
in which the structure is to be placed, hind the structure and to prevent trans-
the availability and cost of construction mitted waves from damaging facilities
materials, and the function of the struc- behind the breakwater. The required
ture. In addition to these factors, the width and height of a breakwater rela-
effects of the breakwater upon its envi- tive to the height and wave length of
ronment must be considered. the design wave are discussed by Saville
et al. (1965). The conventional rubble
Design criteria for fixed breakwa- mound or rock construction is most typ-
ters must consider several factors of ical, although numerous other designs
the p hysical environment, in clu din 9 have been employed with varying degrees
wave climate, sediment transport, bot- of success (Figure 9).
to m to p og ra p hy, c h a racteristics of the
protected areas, tides, and currents at Floatina breakwaters are sometimes
the site. The design wave and the max- a functional alternative 'to fixed struc@-
imum wave must be determined. At this tures, but they have some unique design
point a trade-off is often necessary be- criteria. Unless they ar 'e designed to be
tween economic feasibility and failure- constantly in motion, some sort of an-
proof design (Saville et al. 1965). A chor is necessary. Piles or other anchol-
generalized diagram of a typical rubble- devices are cenerally placed on the bot-
mound breakwater is contained in Fig- tom with li-nes, cables, or chains at-
ure 8. tached to the floating structures (Fig-
ure 10). These anchor lines should have
After the design wave is determin- a tested strength at least twice that of
ed for the construction site, other fac- the design load and- should be as nearly
tors must be considered. Studies must horizontal as possible (Miller 1974b).
be made of the subtrate upon which the
breakwater will rest to determine what Most breakwaters protect waterways,
precautions must be taken to prevent consequently, their siting is dictated
settling and erosion of foundation mate- by the configuration of the shore and by
rial (Saville et al. 1965). Prevention of the desired harbor desion.11any existing
erosion and settling is often accomplish- breakwaters are in the worst possible
ed by using filter blankets or mats sim-' locations as far as obstruction of lit-
ilar to those used under revetments. toral drift is concerned (Snodgrass
This filter cloth material prolongs the 1964). In the future, design modifica-
settlino of the breakwater stones into tions and breakwater locations should
the substrate, which occurs due to the cause minimal disruption of longshore
weicht of the materials and slight move- transport. On relatively shallow, 30 ft
me@t due to wave attack. The core, (9 m) or less, open shorelines, fixed
cap, facing, and foundation material of breakwaters are considered the better
the breakwater must be chosen to pre- choice (Seymour and I -saacs 1974). Float-
vent damage or component displacement ing breakwaters interfere less with sand
by the design wave. movement, water circulation, and fish.
habitat and are preferred for temporary
Wave deflection and absorption is a installations in deep water, or where
primary function of breakwaters. This bottom conditions are unsuitable for
function is affected by the type of placement of a fixed structure (Miller

SUBMERGED BREAKWATER

DESIGN WATER LEVEL CAP

C50 FACING MATERIAL

CORE MATERIAL

'-FILTER LA7@r SEABED

EMERGENT BREAKWATER

CA P -4-
QQ

DESIGN WATER LEVEL FACING MATERIAL

CORE MATE RIAL
,@FACING M
ERIAL

I 7A@

FILTER LAYER SEABED

Figure 8. Cross-sectional view of typical submerged and emergent rubble-mound breakwaters. Dimensions and
detail,s are determined by particular site conditions.

"IN

Figure 9. This unconventional zig-zag breakwater design has performed well
and has stopped further erosion of the bluff at this site. Photograph courtesy of
the State of Michigan,Department of Natural Resources.

.,o-FREEBOARD

WATER LEVEL
FLOAT--4'**

TETHER--@*

MOORING
BALLAST"w"'" LINE

ANCHOR,-,---,
QCFAN FLOOR MO /, /,
ORIN
L , N
G
E
%ANCHOR

Figure 10. Cross-sectional view of a tethered floating breakwater. Materials, dimensions and details are
determined by particular site conditions.

1974b). If disruption or obstruction of an artificial fish habitat, it can also
littoral drift is unavoidable, provisions function as a breakwater. They are
must be made to allow for bypassing inexpensive and are considered a good
sand to avoid starvation of downdrifi method of disposing of used tires
beaches and s hoalin a of waterways. (Alfieri 1975). Floating breakwaters are
also generally less expensive to build
Breakwaters are used for shore and maintain than fixed structures, but
protection either with other structures provide substantially less wave attenua-
(e.c., revetments, seawalls, groins) or tion (Seymour and Isaacs 1974). The
as an alternative to them. Steep shore- cost of shore-connected fixed breakwa-
lines and sandy beaches can be protect- ters compares with that of jetties of
ed and sand accretion can be caused or similar size.
enhanced by breakwaters. Sometirres a
breakwater is placed in the intertidal or Low or submerged offshore break-
subtidal zone as an erosion prevention waters are usually unobtrusive and do
device (Figure 9). not interfere with aesthetic enJoyment of
the shore. Their visual impact is low,
Maintenance requirements must be and they are usually far enough from a
considered when choosino a breakwater beach that they do not interfere with
design . Floating breakwaters are more recreation (Cole 1974). In sorre cases,
vulnerable to extensive wave action and their presence can contribute to the at-
often require more frequent maintenance tractiveness of a beach since they serve
than fixed structures. Vertical face to attenuate incoming waves and provide
breakwaters must be thick or firmly a sheltered, low wave energy area for
braced,or high waves will damage them. recreation. However, construction activ-
Rubble mound structures can generally ities may hamper recreational use of the
with sta n d extensive wave action, but shoreline to a considerable degree, and
are vulnerable to erosion at the toe, the presence of a breakwater may lead
particularly at breaches and ends which to changes in shoreline topography.
can lead to a slope failure (Saville et These chances could be either beneficial
al. 1965). Overtopping waves can dis- or detrimer@tal to recreation. The con-
lodge cap rock. Extended storms can struction of a breakwater can cause
disarrange fa ci n g stones and cause secondary impacts, such as changes in
slumping or structural failure. Sub- use patterns and accumulation of litter.
merged rubble mound structures with Breakwater-associated restrictions on
well-chosen facing material probably re- future public use of an area should be
quire the least maintenance of all types considered before the structure is plac-
(Saville 1960). ed.

The physical effects of construc- Biological. Fixed breakwaters are
tion and presence of a breakwater must subject to the same biological placerrent
be considered in design and location. constraints as jetties,
groins, revet-
These effects are discussed in the Sum- ments, and bulkheads. Riprap or durrp-
mary of Physical and Biological Impacts ed stone faces are biologically more de-
s ectio n. Design of long-lasting, func- sirable than flat faces since they pro-
tional breakwaters is not a simple pro- vide more habitat for aquatic species.
cess. A thorough discussion of design Sloping faces are preferable because
criteria of rubble mound breakwaters is vertical faces lack the shallow water
found in Saville et al. (1965). zone and create less hard bottom sub-
strate. Breakwaters should not be al-
Socioeconomic. Offs hore fi x ed lowed to interfere with fish migratory
breakwaters tend to be more costly than runs or spawning areas (Persaud and
shore-connected structures, partly due Wilkins 1976). The base of the break-
to the problem. of transporting the con- w aters should be p rotected so that
struction materials offshore and partly scouring does n ot affe ct structural
due to the logistics of maintenance(U.S. integrity and, therefore, the aquatic
A rmy Corps of Engineers 1973b). A organisms in the area.
less costly breakwater is the scrap tire
artificial reef. Usually placed to provide Construction activities should be

timed to avoid fish spawning and migra- and random or patterned placement of
tion seasons, and times when birds are rubble components must be determined by
nesting in the vicinity of the construc- individual site studies. Other facing
tio n site. T u rbidity control devices materials include steel or concrete
should be employed whenever possible, sheet piles, timber,and cabions, which
and associated dredging should be mini- are rock-filled wire baskets (U.S. Army
mized to avoid damage to the biota(Flor- Corps of Engineers 1973b). Core material
ida Department of Natural Resources is usually chosen on the basis of its
1973). Shellfish habitat and other areas permeability and whether an individual
rich in plant and animal life should be structure is designed to be permeable or
avoided . Hopper dredges seem to cause impermeable. The cap, if included, is
the least damage to the biota (Thompson generally of rubble or precast concrete
1973) and should be favored over hy- (U.S.Army Corps of Engineers 1973b).
draulic dredoes. However, the use of
hopper dredges is usually limited to the Expected Life Span
construction and the maintenance of en-
trance channels. Data are not available concerning
overall life spans of breakwaters. How-
.Construction Materials ever, periodic maintenance can be ex-
pected to prolong a structure's effec-
Breakwaters can be constructed tiveness. Floating breakwaters are gen-
from a wide variety of materials. Gen- erally not as long-lived as fixed ones.
erally, these can be classified as rock, Breakwaters are constructed of materials
wood, concrete, metal, rubber tires, similar to Jetties; thus, some compari-
filled bags, and rubber-type synthetic sons can be made concerning lifespan.
materials (Table 1). Almost any material Rubble mound structures, if repaired
possessing structural integrity could be when unit displacement is severe, can
used in breakwater construction. last up to 50 yr (U.S. Army Engineer
District, Portland 1975b). Steel, con-
The lifespan of breakwaters de- crete, and timber structures should last
pends greatly on the construction mate- up to 35 yr, depending on site-specific
rials. For this reason, preliminary mate- environmental factors (U.S. Army Corps
rial testing is necessary, both of physi- of Engineers 1973b). Lifespan also de-
cal characteristics and ability to with- pends on the severity of the design wave
stand wave action. Tests of stone, for for a particular structure relative to
example,should include specific gravity, the wave environment it will actually
abrasion, slaking, freeze-thaw, and encounter (Saville et al. 1965).
other relevant examinations (Allison and
Savage 1976). Granites or basalts are Summary of Physical and Biological
preferable to limestone, due to the lat- Impacts
ter's tendency to abrade readily and to
lose weight by dissolution of solids. If Construction effects. Physical ef-
concrete is used, it should be alkali-re- fects from placement of breakwaters are
sistant. Metals should be galvanized or similar to those for Jetties, groins,
coated to resist corrosion and wood piers, and other structures in the near-
should be treated with chemical preser- shore areas. Rock dumping, Jetting or
vatives. Whatever materials are used, driving piles, dredging to a solid bed
they should be chosen on the basis of or required depth, or any other con-
breakwater components being adaptable struction-associated activity which dis-
to substitution, ability to resist corro- turbs the bottom sediment increases tur-
sion and abrasion, durability, and cost- bidity (U.S. A rmy Engineer District,
effectiveness (U.S. Army Corps of Eng- Seattle 1971) and can impact bottom
ineers 1973b). dwelling aquatic organisms, remove sub-
merged vegetation beds, drive away fish
The most common facing material and other mobile organisms, and alter
seen on breakwaters along the United the existing habitat at the structure
States coastlines is rubble,rough stone, site (Morton 1976, Cronin et al. 1971).
or precast concrete in a variety shapes
(Figures 5 and 11). The size, weight, Some decree of noise, air, and

Table 1. Materials used in breakwater construction
as determined from the literature.

F i@_ed_KrTakwa ters____ Floating breakwaters

Pock Wood
Broken quarry stone Cherrically-treated timber
Basalt Plywood

Limestone Concrete
Coquina Cement reinforced with
glass fiber
Prestressed concrete
Wood
Creosote-treated timbers
Copper chromiurr arsenate- Hetal
treated timbers Steel sheet
Chemonite-treated timbers Steel tubing
Pentachloralphenol-treated Aluminum alloy
timbers
Elastorileric material
Concrete Molded polyurethane
Pour-in-place Rubber floats
Preformed Plastic floats
Prestressed Fiberglass
Concrete rubble Polystyrene
Tires
Metal
Steel (galvanized or
coated)
Stainless steel
Aluminum alloy

. .... .. ...

Figure 11. Tribar, a precast, reinforced concrete structure used as
facing on breakwaters and jetties. Photograph courtesy Portland Cement
Associ ati on.

water pollution inevitably accompanies a fixed breakwater can experience de-
construction a cti vity. Petroleum pro- Qradation of water quality and fluctua-
ducts in minor quantities seep into the tions of temperature and salinity (Had-
water from construction equipment and erlie 1970). Sand tends to be deposited
the exhaust emissions add hydrocarbons on the shoreline opposite a detached
to the air(U.S. Army Engineer District, fixed breakwater and immediately updrift
St. Paul 1976a). Turbidity can clog of a shore-connected structure (Figure
gills of fish and other organisms. Toxic 12). The sand deposition opposite a de-
materials and silt suspended by con- tached, fixed breakwater can form a tom-
struction activities can have a detrimen- bolo (a bar or spit that connects an is-
tal effect on the biota of the immediate land with the shore) between the struc-
area (Morton 19,76, Cronin et al. 1971). ture and the shore if the breakwater is
Turbidity effects are most significant long enough in proportion to its dis-
upon Juvenile stages and sessile orcan-
isms. The dislodging of orqanisms - can tance from the shore (U.S. Army Corps of
Engineers 1973b). If conditions are not
cause a feeding spree by predators dur- conducive to tombolo formation, detach-
ing construction periods. ed, fixed breakwaters can still cause
Maintenance effects are much the spit formation on the opposite shore-
same as those resulting from construc- line. This spit then acts as a partial
tion, though often less severe. Break- barrier to littoral drift, allowing the
waters are' constructed in hiah-energy sand to deposit updrift and be eroded
environments which are often @haracter- away downdrift. Floating breakwaters and
ized by sediments with fairly large par- submerged breakwaters have much less in-
ticle size. Large particle-size sediments fluence on littoral drift (Harris and
are less likely lo cause turbidity or tox- Thomas 1974, U.S. Army Corps of Engi-
icity effects than are small particle-size neers 1973b).
sediments characteristic of lower energy Another problem which can occur
environments. within a harbor partially enclosed with
Chronic effects. After construction fixed breakwaters is the generation of
is completed,a new situation exists both secondary waves. These waves result from
at the breakwater and within the pro- reflection within a confined space and
tected zone. Wave energy is much re- can often attain considerable size and
duced inside the breakwater (Ortolano energy (Saville et al. 1965). Careful
and Hill 1972). A fixed breakwater can design will usually prevent this situa-
cause piling-up of water behind it, de- tion; but if it occurs, alterations in
crease circulation, interfere with tides the existing facilities become necessary
and currents, and obstruct littoral drift (Slawson 1977).
(Clark 1974, Sanko 1975). If the break- Breakwaters constructed from the
water is shore-connected, particularly if rock, rubble, and other materials with
it has a shore-parallel leg, the effect irregular surfaces provide a rocky surf
on littoral drift can be severe. habitat on the seaward side,and a rocky
Piling-up most frequently occurs calm habitat on the lee side (Kowalski
behind breakwaters that have restricted and Ross 1975). These new habitats are
openings. This leads to a higher water gained at the cost of the previously
level behind the breakwaters than out- existing bottom dwelling organisms. In
side (Diskin et al. 1970). Differences many situations, the new rocky habitat
in the water levels result in accelerated can be considerably more productive than
flows at the openings or ends of a substrate that previously existed. This
breakwater. The resultant toe scour at is well documented in literature about
the base of the structure can cause artificial reefs.
both local turbidity and damage to the The protected water inside a fixed
structure (Saville et al. 1965). breakwater, with the possible altered
Because of lower wave energy and fluctuations of temperature, salinity,
altered current patterns, the lee side of and water level, can lead to a change in
the plant and animal species composition

BREAK WATER\,,

SAND ACCRETION

lx@

_@7,7

I N A LSHOR ELI NE@'@

DETACHED EMERGENT BREAKWATER

DIRECTION OF NET LONGSHORE
TRANSPORT

`-A D D I T 10 N A L
BREAKWATER _NA SHOALING

SAND
ACCRETION-,
B R E A K W A T E R

ST
E
I AL S H 6'R EL'I 'N'

ATTACHED BREAKWATER
Figure 12. The dotted lines show typical areas of erosion and sand accumula-
tion behind attached dogleg and detached solid breakwaters. The sand formation
behind the offshore breakwater is called a tombolo.
23

with sensitive taxa being replaced by habitat, though any setting of piles or
those with a wider range of tolerance permanent anchor blocks would cause some
(Gifford 1977). Breakwaters are func- minor suspension of sediments.
tionally located in high-energy environ-
ments that are usually typified by rath- Once in place, floating breakwaters
er coarse sediments. The area seaward provide a substrate for fish, algae, and
of a breakwater would be expected to sessile organisms. They interfere only
develop a coarse-sediment environment, minimally with fish migration. By shad-
especially if compared to the previously ing the bottom,floating breakwaters can
existing deeper bottom, a low-energy reduce productivity, but the prolifera-
environment. The enclosed area lan@- tion of attached organisms. and the graz-
ward of the breakwater will, in many ers which they attract may balance or
cases, develop a sediment composition offset their reduction (Gifford 1977).
that is less coarse than previously
existed. This shift in sediment type Cumulative effects. Very little
will cause concomitant shifts in species information was found on the cumulative
distribution, diversity, and numbers. effects of breakwaters or breakwaters in
These shifts can be either beneficial or combination with other structures. If
detrimental. two or more fixed structures are placed
in proximity, the resultant alteration
The creation of a new type of bot- in current patterns could cause scour
tom often results in replacement of a damage to one or more of the structures.
deepwater fish habitat with a shallow The location of structures close to each
shellfish habitat (Snow 19-77). This will other can cause other synergistic ef-
depend upon the biology of the area fects: littoral transport modifications,
where the breakwater is constructed, alterations of wave energy environments,
If sand deposition creates an emergent and alterations of water quality parame-
or intertidal sandbar, then a new type ters, such as salinity and dissolved
of bird habitat may result. The stone oxygen or the concentration of petro-
surface upon and behind the breakwater chemicals. The degree of such changes
may be used by birds. The sandbar must be evaluated case-by.-case.
and rock habitats are preferred by the
gulls, terns, and other beach-dwellinq Structural and Nonstructural
s pecies. Colonial nesting may occur if Alternatives
human disturbance is limited during
nesting season. Breakwater design is a function of
the shape of the structure or area to be
Breakwaters can affect longshore protected, and the direction and sever-
fish migration routes. This has been ity of the wave attack. Given these two
documented for salmonid fry where the conditions, the breakwater cross-section
presence of a shore-connected breakwa- and construction materials will be se-
ter forced them into deeper water than lected on the basis of materials avail-
previous conditions afforded (Stockley ability and cost minimization. There are
1974). The reduction of shallow water several possible alternatives to propos-
areas decreased the available salmonid ed breakwaters.
fry migration routes. The fry were ex-
posed to increased predation because It is possible to dispense with the
they would not migrate around the breakwater and devise other means to
structure.The effects of floating break- deal with the wave attack on the harbor
waters are generally less severe and or structures. The higher wave climate
the Washington Department of Fisheries could be dealt with by increasing the
(1971) strongly recommends their use to structural design of piers, floats, ves-
protect fish resources. Water circula- sel mooring systems, and other features
tion is only slightly affected, and the of the harbor. This response is gener-
piling-up of water behind the floating ally more feasible in harbors for large
breakwaters is negligible because they ships because small craft cannot take
are anchored by cables or widely spac- repeated pounding against structures.
ed piles (Kowalski 1974b). Installation
causes much less disturbance of bottom If the shoreline must be protected,

alternatives to a breakwater are revet- considered.undesirable because they pre-
ments, seawalls, bulkheads, increased clude a shallow water area, while 30-de-
beach cross-section, or other methods. gree slopes approximate natural condi-
tions.Though raw earth or gravel facings
To compensate for reduced water are similar to the normal habitat of
circulation and attendant problems in- juvenile salmon, they allow erosion and
side a basin protected by a breakwater, damage shellfish beds (Washington De-
a permeable b reak water or floatin g partment of Fisheries 1971).
breakwater could be substituted for a
fixed, solid structure. Floating break- Limited data are available concern-
waters have the additional advantage of ing altered environmental conditions.
being portable and, to some extent, re- Algae and hydroids have been noted on
usable. breakwaters in Puget Sound (Millikan et
al. 1974, Smith 1976) and fish were
In shallow water areas not subject abundant at one breakwater (Smith 1976).
to severe wave attack, vertical wood Smith (1976) also reported three dis-
pile or sheet pile structures are often tinct zones of marine invertebrates
used as breakwaters. If rock is avail- along a breakwater. Rigg and Miller
able, a low, rubble mound structure (1949) observed surf habitats on the
may prove equally effective and econom- outer face of a breakwater and typical
ical, while alleviating some of the envi- quiet water types of sessile organisms
ronmental problems associated with fixed on the inner face. They also observed
breakwaters and vertical surfaces. an unexplained abundance of starfish at
one breakwater. Millikan et al. (1974)
When the breakwaters are used to noted large amounts of herring spawn on
create a basin, there is usually a shape evergreens submerged in the vicinity of
that will minimize the total cost and re- breakwaters; flocks of scoters fed
duce the dredging required for the ba- heavily upon the spawn.
sin. Placing the basin in deeper water
may increase breakwater costs, but de- Physical impacts, as described in
crease dredging costs. The reverse is the general section,were expected to re-
also true. Assuming there is no problem sult from the construction and presence
with property ownership or rights, the of breakwaters on the north Pacific
shape of the basin can be altered to coast (Coastal Region 1). The major bio-
achieve a different balance between logical impact discussed was upon salmo-
breakwater and dredging or between nid fry which became vulnerable to pre-
development of water area versus land dation due to an interference with mig-
area. ration (Richey 1971). In some cases
shellfish beds were destroyed by break-
Regional Considerations water placement, but in others new clam
beds were established in sand accretion
Breakwaters are found at virtually areas. Shoaling around one breakwater
every harbor and estuary on the north was expected to alter benthic habitat,
Pacific coast (Coastal Region 1). They preclude bottom use by fish and shell-
are primarily intended to protect water- fish, and create additional bird habitat
ways from extensive wave action. The (U.S. Army Engineer District, Seattle
State of Washington has outlined strict 1971). However, Rigg and Miller (1949)
guidelines for their design and place- reported that aAother breakwater in
ment. These include the following phy- Puget Sound had no noticeable effect on
sical placement criteria: at least two organisms in its vicinity after 10 yr.
gaps must be provided to allow water
circulation and flushing; the structures Most of the breakwaters in southern
must be less than 250 ft (69 m) from California (Coastal Region 2) are asso-
M H H W (mean higher high water) line ciated with harbors,often small boat
and not be below 0 ft MLLW (mean low- moorages. In a few cases, detached off-
er low water); facings must be perman- shore breakwaters function as shore pro-
ent material and stair-step design; the tection structures. Both shore-connect-
openings must not be shallower than the ed and detached breakwaters can be found
dredged enclosure. Vertical faces are in this region, and most of these are

constructed of rubble mound. Physical with complex patterns of littoral trans-
impacts fro m breakwater construction port. Physical and biological impacts
and presence are similar to those pre- are expected to be insignificant though
viously described. Deterioration of no quantitative studies have been made.
water quality is frequently a problem in Unless well marked, they may be a navi-
breakwater protected harbors (Slawson gation hazard to small craft at low
1977, Carlisle 11077). Red tides (dino- tide.
flagellate blooms) are severe in most
harbors in the Los Angeles-Long Beach Little information was found con-
area (Slawson 1977) and probably occur cerning breakwaters in the north Atlan-
frequently wherever circulation is im- tic (Coastal Region 7).
paired.
Breakwaters are frequently used in
Breakwaters in the Gulf of Mexico the Great Lakes (Coastal Region 8) for
(Coastal Region 3) are used both for shore and harbor protection. Most are
shore protection and in harbor areas. shore-parallel and detached. Construc-
They are placed either parallel or per- tion materials include many of those
pendicular to the shoreline. Most act listed in Table 1. One rather unusual
as littoral drift barriers and require design is that of a steel or concrete
modifications to bypass sand. Construc- zig-zag wall parallel to shore with its
tion materials are rock, concrete, sheet crest Just above mean water level (Fig-
piling, timber, and scrap tires. Scrap ure Q). One physical impact of break-
tire breakwaters are being developed waters which is unique to the Great
for protection of the Florida coastline Lakes is the enhancement -and prolonging
(McAllister 1977). of harbor icing. Protected water behind
breakwaters ices over earlier in the
Breakwaters are less common than fall (U.S. Army Engineer District, Buf-
groins in south Florida (Coastal Region falo 1975a) and remains frozen longer in
4). Most of the existing ones are part the spring.
of small boat harbors. A large portion
of south Florida is characterized by nat- JETTIES
ural offshore reefs and is also somewhat
p rotected by the Bahamas (McAllister Definition
1977). Floating breakwaters often at-
tract marine animals and is one case a "A jetty is a structure extending
community of marine invertebrates and into the water to direct and confine
fish was well established on a floating river or tidal flow into a channel and
breakwater within a month of its place- to prevent or reduce shoaling of the
ment (Gifford 1977). channel by littoral material. Jetties,
located at the entrance to a bay or riv-
No unique information concerning er, also serve to protect the entrance
breakwaters in the south A tl a ntic channel from wave action and cross cur-
(Coastal Region 5) was found. Physical rents. When located at -inlets through
and biological impacts were similar to barrier beaches, they also stabilize the
those desribed for other regions. inlet locations." (U.S. Army Corps of
Engineers 1973b).
Sandbag sills (sand-filled nylon
tubes or lines of sandbags) were the The most common type of jetty is
only type of breakwater for which in- one extending into the ocean at the en-
formation unique to the middle Atlantic trance to a bay or river (Figure 13).
(Coastal Region 6) was found. These However,training works (including train-
are utilized to prevent erosion of indi- ing walls) located in estuaries and
vidual waterfront lots or to improve the along rivers to guide currents and as-
effectiveness of a groin system. They sist in channel deepening are also com-
are placed much farther inshore than monly called Jetties. Sometimes a struc-
most breakwaters and are considerably ture placed in a river or, on an estua-
smaller than the usual breakwater. rine beach to direct currents and stabi-
Placement is in the subtidal zone, just lize the beach is called a Jetty or a
below mean low water, on sand beaches groin (see Glossary).

Nvjfr-@. ''0

Ar- Ift @',"

Z4.

"or
Figure 13. Jetties at mouth of Coquille River, Bandon, Oregon. Photograph courtesy
of U.S. Army Engineer District, Portland, Oregon.

Structure Functions (1) The tidal prism and cross-
section of the gorge in the
Jetties located at coastal entrances natural state;
to bays or rivers usually have multiple (2) Historical changes in inlet
purposes, including: position and dimensions..;
(3) Range and time relationship
0 stabilize the inlet location; (lag) of tide inside and out-
0 direct and confine flow or pre- side the inlet;
vent or reduce channel s hoalin g (4) Influence of storm surge or
from littoral drift material; wind setup on the inlet;
0 protect vessels using the entrance (5) Influence of the inlet on
from wave or current action. tidal prism of the estuary and
effects of freshwater inflow
When taken together, these func- on the estuary;
tions have aspects of groins and break- (6) Influence of other inlets on
waters, as well as jetties. Jetties locat- the estuary; and
ed inside of estuaries or along rivers (7) Tidal and wind-induced cur-
may have the single function of direct- rents in the inlet.
ing and confining flow to reduce chan-
nel shoaling. Sometimes, these struc- b. Hydraulic Factors of Proposed
tures concurrently function as groins Improved Inlet.
because they may stabilize or otherwise
change the movement of material along (1) Dimensions of the inlet ...
an estuarine or riverine beach. (2) Ef fects of inlet improvements
on currents in the inlet, and
Site Characteristics and Environment on the tidal prism, salinity
Conditions in the estuary, and on other
inlets into the estuary;
Jetties are usually placed on one (3) Effects of waves passing
or both sides of an inlet, extending through the inlet; and
from above high water on the shoreline (4) Interaction of the Hydraulic
but beyond low water (Ortolano and Hill Factors (item b) on Navigation
1972). They sometimes extend out to and Control Structure Factors
the depth of the associated navigation (item c and d).
channel (U.S. Army Corps of Engineers
1971b) and usually extend beyond the C. Navigation Factors of the Proposed
surf zone (Gifford 1977). Most jetties Improved Inlet.
are found at river or bay openings into
the ocean or the Great Lakes. Natural (1) Effects of wind, waves, tides
and man-made inlets, when unaltered, and currents on navigation
usually interrupt the longshore move- channels;
ment of sand. This causes bar formation (2) Alignment of channel with re-
in the inlet mouth (U.S. Army Corps of direction and natural channel
Engineers 1971b). Jetties are also lo- of unimproved inlet;
cated at natural and man-made inlets (3) Effects of channel on tide,
through barrier beaches (U.S. Army tidal prism and storm surge of
Corps of Engineers 1973b). the estuary;
(4) Determination of channel di-
Placement Constraints mensions based on design ves-
sel data and number of traffic
Enqineering. A number of factors lanes; and
must be considered when choosing a de- (5) Other navigation factors such
sign and a site for a jetty. The Shore as:
Protection Manual (U.S. Army Corps of (a) Relocation of navigation
Engineers 1973b) recommends ca ref ul channel to alternate
study of the following: site;
(b) Provision -for future ex-
Ila. Hydraulic Factors of the Existing pansion of channel dimen-
Inlet. sions; and

(c) Effects of harbor facili- (Snow 1973). Jetties provide a spot for
ties and layout on chan- fishing, and safe passage to and from a
nel alignment. harbor for small craft. In addition,
d. Control Structure Factors. durino the construction period there may
(1) Determination of jetty length be a beneficial economic effect in the
and spacing by considering area (U.S. Army Engineer District, Port-
the navigation, hydraulic, land 1976e).
and sedimentation factors;
(2 ) Determination of the design Biological. When planning jetty
wave for structural stability construction, the effects of the struc-
and wave runup and overtop- ture on area wildlife propagation and
ping considering structural movement should be considered (Coastal
damage and maintenance; and Plains Center for Marine Development
(3) Effects of crest elevation and Service 1973). Migratory runs of fish
structure permeability on may be affected by changes in an inlet.
waves in channel. Construction activities should be care-
e. Sedimentation Factors. fully planned to avoid fish migration or
(1) Effects of both net and gross spawning runs (Persaud and Wilkins
longshore transport on method 1976). Dredging to bypass or remove
of sand bypassing, size of accumulated sand should also be sched-
impoundment area, and chan- uled for times of relatively low produc-
nel maintenance; and tivity (Thompson 1973). Care should be
(2) Legal aspects of impoundment taken in the choice of downdrift sand
area abd sabd bypassing pro- release sites to avoid movement of sand
cess. onto productive fish and shellfish areas
f. Maintenance Factor. Dredging will or rich plant communities (Cronin et al.
be required,especially if the cross- 1969). If the accumulated sand is not
section area between the jetties is returned to the littoral drift, it
too large to be maintained by the should be disposed of carefully.
currents associated with the tidal
prism. " Construction Materials

To be effective in preventing the Jetties along the United States
shoaling of a navigation channel, jetties coastlines are usually built of rubble
must be impermeable. However, imper- or quarried stone (U.S. Army Corps of
meability causes downdrift sand starva- Engineers 1973b). Other materials oc-
tion so methods have been developed to casionally used, particularly in the
bypass the sand which accretes behind Great Lakes, are steel sheet pile cells,
the updrift jetty. These include bypass cassions, and timber, steel, or concrete
pumping, placement of the weirs in an cribs. Prefabricated concrete components
otherwise solid jetty, sand transfer (Figure 14) are sometimes used on the
plants, and dredging. Dredging is also outer layer.
used to remove bars which form in the
channels lacking adequate currents to Caps on rubble mound jetties are
maintain depth by scour (U.S. Army often concrete embedded with large
Corps of Engineers 1973b). stone. Thick bedding layers of gravel
or stone often extend out from the fac-
Socioeconomic. The size, type, and ing layer affording the toe of the
construction materials of the Jetties de- structure protection from scour. Medi-
pends, in part, on available funds for um-sized stone is usually placed between
construction and maintenance (U.S. the large stone or shaped concrete fac-
Army Corps of Engineers 1973b). N ei- ing. Most cribs, cassions, and sheet
ther the construction nor maintenance pile cells are filled with dredged mate-
should severely hamper commercial or rial, gravel, or small-sized quarry
recreational use of the area around the stone and capped with concrete or large-
jetty site (Persaud and Wilkins 1976). sized cover stones lying on a bedding
It is also important to consider the final layer. A stone mattress and riprap are
appearance of a jetty, either alone or usually placed at the base of the verti-
as part of the overall shoreline scene cal walls. These toe structures have

I-A 6
-00-

9M
tic
L
A -Ip,

Figure 14, Dolosses are being installed as protective facing on this ru6ble mound
jetty in Humboldt Bay, California. Note nort@ jetty in background. Photograph
courtesy of U.S. Army Corps of Engineers, South Pacific Division.

sloped sides and protect the base of the area covered by the jetty will be lost
structure from scour and undermining as a bottom habitat (Virginia Institute
(U.S. Army Corps of Engineers 1973b). of Marine Science 1976), but a new type
of habitat will be created.
Sheet piles are not satisfactory in
high wave energy environments, but Chronic effects. - The presence of
can be used where the wave climate is jetties at a river or bay mouth alters
less severe. Steel, used as sheet piles, both river outflow and tidal currents
should be coated to prevent corrosion. (U.S. Army Engineer District, Portland
Timber must be treated with preserva- 1975b). These alterations are often felt
tives to prevent attack by marine inver- well into the estuary and may have wide-
tebrates, such as borers and gribbles. spread effects. Altered rates of nutri-
Concrete is immune to pests, but an im- ent and sediment accumulation can occur
proper mix can deteriorate rapidly in in salt marshes. Salinity and tempera-
seawater (U.S. Army Corps of Engi- ture changes can occur. The tidal prism
neers 1973b). can be altered since overall circulation
patterns within an estuary are affected
.Expected Life Span by the change in water flow through a
stabilized channel. The flushing charac-
Rubble mound jetties can last up teristics of the estuary can be changed
to 50 yr if properly designed and main- and wave height often increased in its
tain ed (U.S. Army Engineer District, lower regions (Carstea et al. 1975a).
Portland 10975b). Maintenance includes
both replacing displaced armor compo- Outside the estuary,the most sig-
nents after particularly severe storms nificant effect of jetties is the alter-
and major repairs every 15 to 20 yr to ation of littoral transport. Littoral
replace broken, worn, or lost compo- transport is obstructed by the jetties;
nents. Sheet pile jetties, whether steel, sand is impounded updrift and eroded
timber or concrete have shorter life- downdrift. If a single jetty is install-
spans due to abrasion by sand and wa- ed, the opposite side of the inlet can
ter-borne debris, corrosion by salt wa- erode severely. Also, a shoal can form
ter, and attack by borers or gribbles at the tip of a single jetty updrift of
(U.S. Army Corps of Engineers 10-73b). an inlet and eventually fill in the in-
They can last anywhere from 10 to 35 let. The influence of a lietty extends
yr depending on the conditions of their well beyond its immediate vicinity.
environment. Downdrift beaches retreat due to sand
starvation unless measures are taken to
Summary of Physical and Biological bypass the sand that accumulates updrift
Impacts of the jetties (Ketchum 1972). Changes
in foredune height have been reported
Construction effects. As with any downdrift of ietties (Demory 1977).
major construction activity in the coast-
al zone,placement of jetties causes some The channel formed by jetties often
temporary disturbance, such as turbid- migrates from the original location to
ity caused by resuspension of bottom an area adjacent to one of the lietties,
sediments. Toxic substances present in scouring the bottom and causing
sediments can be released (Carstea et turbidity. As the channel nears the
al. 1975a). Noise, and air and water jetty, the scouring action can erode the
pollution will accompany construction base of the Jetty and necessitate re-
activities (U.S. Army Engineer District, pairs or strengthening of the structure
St. Paul 1976a). During construction, base. Sandbars tend to migrate seaward
nearshore currents can be disrupted. in the presence of jetties (Kieslich and
Erosion and accretion can occur locally Mason 1975). Dredging is usually requir-
in patterns quite different from those ed to maintain a channel of sufficient
previously existing or those which de- depth since the tidal currents are inad-
velop after completion (Anderson 1975). equate to keep the channel scoured (U.S.
Suspended sediments may reduce pri- Army Corps of Engineers 1973b).
mary productivity and smother benthic
organisms (Cronin et al. 1971). The The placement of jetties destroys

some bottom habitats and creates new alternative can be very costly and can
ones . Rubble mound structures provide result in the channel being unusable for
attachment sites for sessile organisms, certain periods due to the inability of
and the irregular surface can support a dredging equipment to provide and to
diverse community of rocky shore plants maintain desired depths for navigation.
and animals (Ortolano and Hill 1972). It is also possible that the dredging
Sand accretion areas can provide new and disposal process will have an impact
h a bitats for shellfish and shorebirds on the surrounding envirorrrent which is
(Snow 1977). Areas where erosion takes far greater than the impact due to jet-
place often become populated by fish ties.
which require deeper water. Jetty relat-
ed fisheries can develop (Ortolano and Regional Considerations
Hill 1972). However, the presence of
Jetties may limit or alter the normal Jetties have been built, or are
movement of fish and crustaceans into planned, for virtually every inlet of
and out of estuaries (Cronin et al. significant size in the North Pacific
1971). Physical changes in water circu- (Coastal Region 1). In some cases only a
lation, flushing, current patterns, and single jetty has been placed but most
shoaling within the estuary may severe- inlets are stabilized by a pair of jet-
ly degrade or alter existing habitats ties. All are placed perpendicular to
(U.S. Army Engineer District, Portland the shore and are of rubble mound or
1975b). In some cases altered circula- quarried stone construction. No unique
tion patterns are beneficial. placement constraints apply to this
coastal region. Construction materials
Cumulative effects. Most of the include rock (usually basalt), quarry
effects due to jetties are noticeable in stone, and, in at least one case, dolos-
the immediate vicinity and in the em- se. Average life span of jetties in this
bayment or river 'and coastal area where area is about 50 yr with major repairs
they are constructed. There is gener- expected to be necessary during that
ally little reason to construct several period (U.S. Army Engineer District,
pairs of jetties in proximity. Therefore, Portland 10-75c, 1976e).
cumulative effects due to proliferation
of jetties are not obvious. It is possi- Long-term impacts include erosion
ble, however, that numerous jetties and accretion changes, habitat altera-
along a coastline could have the same tions at the jetties and within estuar-
cum,ulative effects upon littoral trans- ies, and changes in tidal patterns and
port as a numer of groins could. water quality. Storm waves have caused
severe damage to jetties as a result of
Structural land Nonstructural scouring (Wong 1970). A number of sand
Alternatives spits have been altered, breached, or
Jetties are normally used to pro- destroyed as a result of jetty-caused
vide channel or inlet stabilization and to current changes. The foredune at Tilla- -
reduce the amount of dredging required mook,Oregon, is many times hiqher than
to maintain the inlet or channel. There it was before construction of fhe Tilla-
mook jetty. No summer return of winter
are different materials and configura- sand loss was observed in the first few
tions available for jetty construction. It years following extension of Yaquina
is also possible to use other structures, Bay, Oregon, Jetty (Demory 1977). Jef-
such as groins, in conjunction with Jet-
ties to reduce or modify effects of I the ferson (1974) reported that configura-
jetty on adjacent areas. tion of some of Oregons coastal bays
has been changed by the construction of
Nonstructural alternatives fall into jetties. All along the Oregon coast,
two cateoories. The first is to do noth- chances in habitat, apparently connected
ing and -forego the use of the waterway with presence of or changes in jetties,
for navigation and possibly adjacent have been observed (Snow 1977). In one
lands for some form of development. case, a jetty's influence on littoral
The second alternative is to maintain transport contributed to the breaching
of a sand spit. This allowed sand and
navication by means of dredging. T his boulders to enter a protected lagoon and

bury most existing commercial oyster mainland and on barrier islands. They
beds (Jefferson 1974). Jefferson (1974) are used to stabilize inlets, train cur-
also blames jetties for contributing to rents, and protect beaches. Lying per-
modification of estuarine salt marsh pendicular to the shoreline, they extend
habitats. beyond the surf zone. Placement con-
straints are those generally applicable
Jetties are commonly found at to jetties everywhere. However, the
coastal inlets throughout southern Cali- Florida Department of Natural Resources
fornia (Coastal Region 2). In several (1973) has pointed out that Jetties are
cases, they are associated with man- not permanently successful in fulfilling
made harbors (Reish 1962). Rubble their function unless they are integrat-
mound construction utilizin g rock is ed with other shore protection measures
most common. No placement constraints as part of a comprehensive program cov-
are unique to this coastal region. Sea ering large stretches of shoreline. No
mussels, barnacles, limpets, snails, and physical or biological impacts unique to
other sessile and cryptic organisms pop- this coastal region were found.
ulate most of southern California's jet-
ties (Reish 1964). A green algae, Ulva No data were found that were unique
dactylifera, is a pioneer species on new- to jetties in the south, middle, or
ly constructed jetties (Reish 1969) and north Atlantic (Coastal Regions 5, 6, or
is soon joined by a variety of marine 7.)
animals. No unique construction related
physical or biological impacts were iden- Jetties in the Great Lakes (Coastal
tified for Coastal Region 2. Long-term Region 8) are often constructed of mate-
impacts were similar to those previously rials other than rubble mounds. Steel
described. sheet pile cells, cassions, and timber,
steel,- or concrete cribs are also uti-
Jetties in the Gulf of Mexico(Coast- lized. Timber and steel sheet piling in
al Region 3) are placed in inlets in bar- single rows are sometimes used in shel-
rier islands, as well as at river mouths. tered areas (U.S. Army Corps of Engi-
Placement constraints are those previ- neers 1973a).
ously described. Most are rubble mound
structures constructed of stone, includ- GROINS
ing granite. Varying salinity and cur-
rent regimes often exist on opposite Definition
sides of jetties, and if the structure is
hooked to protect a harbor, there may A groin is a rigid structure built
often be varying wave climates inside out at an angle (usually perpendicular)
and outside (Gifford 1977). Jetties pro- from the shore to protect it from ero-
vide a habitat for sessile and cryptic sion or to trap sand. A groin may be
organisms that attract fish and birds. further defined as permeable or imper-
The physical and biological impacts of meable, depending on whether or not it
jetties have been described previously. is designed to pass sand through it.
In addition to those described, Hastings
(1972)reported that fish from more trop- Groynes (British), spur dikes, and
ical areas were found in the vicinity of wing dams are included in this defini-
jetties. On the channel side ofjetties, tion. Sometimes the word Jetty is used
the organisms tend to be those with a interchangeably with groins; however,
greater tolerance for the rapid salinity Jetties generally have a different func-
changes, periods of low water clarity, @ion. -under certain conditions a struc-
and strong tidal currents while those on ture may be carrying out functions nor-
the outside were tolerant of surf condi- mally associated with both jetties and
tions (Hastings 1972). Hastings (1972) groins. An example would be directing
further reported that most fish found stream flow in a river,while concurrent-
near jetties were secondary consumers. ly stabilizing a beach.

Jetties are common in south Florida Structure Functions
(Coastal Region 4) and are found at in-
lets and harbor mouths both on the The most common function of a groin

is to provide or maintain a beach groin field is to trap sand and to mini-
Groins can be designed in various con- mize sand movement downcoast, groins
figurations to do any of the following: should be built to. a height that will
prevent normal high water from carrying
0 build or widen a beach by trap- sand over them. When continued movement
ping littoral drift; of sand is desired, the height of groins
0 stabilize a beach by reducing the should be near to or below normal high
rate of sand loss; tide level (Balsillie and Berg 1973).
0 prevent accretion in a downdrift Length of groins is also dependent on
area by acting as a littoral bar- the degree of littoral drift obstruction
rier. desired and on existing and desired
beach slope (U.S. Army Corps of Engi-
The above functions all assume neers 1-0,73b). Length is measured from
existence of either a sandy beach and/ the groin's landward end at the berm to
or a littoral supply of sand. Groins its seaward end. The seaward end usually
can affect areas both updrift and dov,n- extends to the point where incoming
drift. The functions of building, or swells exert the greatest force on the
stabilizing a beach may have the effect sand bottom (Coen-Cagli 19:32).
of starving an adjoining area.
The spacing of groins in a groin
Site Characteristics and Environmental field is subject to a number of factors.
C onditions As a general rule, groins should be sep-
arated by a distance two to four times
Groins are constructed on many their length (Savage 1959, U.S. Army
types of shorelines, but most commonly Corps of Engineers 1973b). However,
on shallow, sandy, or shingle beaches. spacing must assure that minimum beach
Since they can be used to prevent ero- width is maintained. A more detailed
sion, build or widen beaches,or prevent discussion of the factors involved in
downdrift accretion, their siting on the groin spacing is found in -the Shore Pro-
shoreline is dictated by their intended tection Manual (U.S. Army Corps of Engi-
function (Figures 15, 16, and 17). For neers 1973b).
a groin or groin system to function,
there must be a supply of sand provid' Though the majority of groins are
ed by littoral transport. Other than straight, some are built with a length-
this common characteristic, no generali- wise curve or are L-, Z-, or T-shaped
zations can be made concerning environ- (Balsillie and Berg 1973). Their crests
mental conditions or groin sites. can be level or can slope downwards to-
ward the seaward end (U.S. Army Corps of
Placement Constraints Engineers 1973b). In a groin field, suc-
cessive downdrift groins can be made
Engineering. A groin must be de- progressively shorter or lower, with the
signed for a specific site. There is no latter variation being preferable (Coen-
best design,optimum choice of construc- Cagli 1932).
tion,nor ideal length or spacing between
groins that can be applied generally to Whatever the des i gn of groins,
all situations. The substrate of the site starvation of downdrift beaches should
must be studied to determine structural be prevented. If a newly constructed
limitations, material availability, and groin will capture nearly all littoral
maintenance requirements (U.S. Army drift, artificial nourishment is desir-
Corps of Engineers 1973b). Other char- able to assure a supply of sand to down-
acteristics of a shoreline must also be coast beaches (Sanko 1975). Another
known before a single groin or a groin method of filling behind a groin in-
field is constructed. These are angle volves placing a weir or series of weirs
of wave ap proach , volume of littoral along its length. This allows a portion
d rift, wave strength, current, and of the littoral drift to continue down-
shoaling patterns (Horikawa and Sonu drift (U.S. Army Corps of Engineers
1968). 1973b). This structure is effective only
if there is no movement of the stone
If the objective of the groin or material.

-1 ------ 4U,
OdICSSI& Jill

-,.Ott

Figure 15. Concrete groins at the base of a revetment on the Gulf coast of Florida.
Photograph by E. L. Mulvihill.

7 "Mu'r,7",
mof M wI"-r(!P----

MM
114

06"

. . . . ... ...

Figure 16. Timber pile groins, Puget Sound,
Washington. Photographs by C. A. Francisco.

3-7

4,14

%-V

Figure 17. Rubble mound groin in the southeastern United States. Photograph by
V. J. Bellis.
'W
h

It is imperative that groins extend Groins can be built of almost any
to the crest of the beach berm, or high material which will remain in place and
wave action will cause flanking (U.S. not deteriorate rapidly. Impermeable
Army Corps of Engineers 1973b). If groins are often constructed of sheet
the groin extends out from a seawall or piles supported by piles (U.S. A rmy
bulkhead, it should be solidly anchored Corps of Engineers 1973b). The sheet
to that structure (Coen-Cagli 1932). piles are wood, steel, or -a combination.
Other materials for impermeable groins
Socioeconomic. The cost of groins include quarried stone, concrete, rub-
varies greatly, depending on construc- ble, and asphalt (Figure 19). Permeable
tion materials, anticipated wave action, groins (Figure 20) are constructed of
tidal range, and whether ad ditio n a] similar materials, as well as of sand-
beach nourishment will be necessary bags, sand-filled nylon tubes, wood, and
(U.S. Army Corps of Engineers 1971b). earth (Erchinger 1970). Stone groins
A method of determining economic feasi- should have filter cloth under them to
bility of groin const@uction involves prolong the life of the structure by de-
comparison of construction and mainte- laying settling into the substrate.
nance costs with the cost of periodic
beach nourishment (Berg and W atts Expected Life Span
1971). Prefabricated groins are often
economical to install. Timber groins and Recorded life spans of groins vary
low permeable structures are probably from 2 to 50 yr. Rubble or quarried
the most economical for an individual stone is reported as the longest lasting
property owner (Horikawa and Sonu construction material, followed by steel
1968, Pallet and Dobbie 1969), Gabion (25 yr), treated wood (20 yr), aluminum
groins (Figure 18) require extensive (15 yr), and nylon bags (2 yr) (U.S.
maintenance. They are also unsightly Army Engineer District, Los Angeles
and vulnerable to damage by drifting 1974a, Chabreck 1968). All materials
logs or other heavy debris. The aes- vary in permanence, depending on salin-
thetic effects of groin placement should ity, wave climate, and water tempera-
not be neglected. A sandy beach is ture.
more attractive than an eroded one.
However, the groins that protect it Summary of Physical and Biological
should be as unobtrusive as possible Impacts
(Coastal Plains Center for Marine Devel-
opment Service 1973). Construction Construction effects. Turbidity is
activities should not interfere with re- a major impact of groin construction
creational use of a beach. (U.S. Army Engineer District, St. Paul
1976b). Resuspension of toxic materials
Biological. Very little information can also occur, as can some noise, air,
is available concerning biological con- and water pollution. Compared to jetties
straints on placement of groins. Carstea and breakwaters, these physical effects
et al. (1975a) recommended that restric- should be less because groins are rela-
tions be placed on the amount of sedi- tively small structures.
ment resuspended by construction activ-
ities. The effects of groin construction Chronic effects. Groins are intend-
and siting on wildlife propagation and ed to prevent erosion or to build the
movement should be known and efforts beaches. However, in some cases they
made to minimize adverse effects (Snow contribute to erosion and to beach loss
1973). Construction should be planned elsewhere that is at least as serious as
to avoid interference with fish spawning what they were designed to prevent. A
areas or migratory routes (Persaud and number of cases have been reported where
Wilkins 1976). Groins which capture all downdrift beach erosion was aggravated.
littoral drift, thus encouraging or ag- An example of this is described by
gravating downbeach erosion , should Pallet and Dobbie (1969) where downdrift
not be constructed. Such erosion can cliff erosion was increased by the pre-
degrade aquatic resources. sence of a groin system. In spite of
this problem, groins serve their intend-
Construction Materials ed functions. Beaches are stabilized,

Rk":
AR
I'J @'
.. .. ... .
n'a

@J- -

Figure 18. Gabions are used to construct groins on the
Great Lakes. Photograph courtesy of State of Michigan,
Department of Natural Resources.

TIE TO CAP (OPTIONAL)
BLUFF@+---
DESIGN WATER LEVEL
SAND BEACH

TOE PROTECTION

Figure 19. Side view of an impermeable groin. Construction materials, dimensions and details to be
tIETo
BL UFF

determined by particular site conditions.

Ott,
%tit
tit,,

Z-@ a
'A", mW

Figure 20. Prefabricated permeable groin. This component has also been
used in the construction of breakwaters. Photograph courtesy of Portland
Cement Association.

fore dunes are protected, and beach to accelerate downdrift beach erosion by
width can be increased by careful reducing the amount of sand transported
placement of groins (Berg and Watts to them, the placement of one groin
1971, Pallet and Dobbie 1969). Down- often leads to the need for another a
d rift beach starvation results when distance away. A series of groins will
groins completely obstruct littoral drift. take longer to fill, prolonging the pe-
Downdrift beaches will recede until the riod in which downdrift shorelines are
groins are filled and sand bypassing exposed to erosive factors.
occurs (Schijf 1959). If groins are used
to widen beaches,they can be filled with Structural and Nonstructural
sand after construction thereby lessen- Alternatives
ing the p ote ntial impact downdrift. The function of groins is either to
Among the problems that accom- stabilize a beach by preventing movement
pany groins is scour on the lee side. of sand, or to trap littoral sand which
This can often be minimized by includ- would otherwise move past the area under
ing weirs along the length of a groin or consideration. There are few alterna-
by making the str u ctu re permeable tives available which will accomplish
(Horikawa and Sonu 1968; U.S. Army these functions. The most obvious is an
Corps of Engineers 1973b). offshore or parallel breakwater which,
by diminishing wave energy, will disrupt
The appearance of a shoreline on the movement of sand along the beach and
which groins have been built changes thereby cause an accumulation of sand in.
fro m one with long, fairly straight the lee of the breakwater.
stretches of sand to one with a series
of indentations downdrift of each groin. Besides the immediate function of
This is due to pattern of erosion and the groin, two other purposes are imme-
accretion caused by the alteration of diately apparent:
longshore d rift ( Horikawa and Sonu
1968). If the structures are permeable, 0 to provide a wider beach for aes-
this recurring series of arcs is less thetic or recreational purposes;
pronounced than if they are imperme-
able. 0 to provide a wider beach to pro-
tect land or structures landward
The accretion of sand behind of the beach.
groins buries those bottom organisms
which cannot move away from the area. Both of these objectives can be ac-
However, this disadvantage is usually complished by the nonstructural alterna-
offset by the increased sand sur-face tive of beach nourishment. The beach is
area provided (Ortolano and Hill 1972). built up by artifically adding sand from
The surface of groins serves as an at- offshore or onshore sand sources. There
tachment site fo r sessile organisms are numerous examples of this construc-
(Cronin et al. 1969), and groins often tion practice, particularly along the
provide a protected area for establish- east coast of the United States. This
ment of beach vegetation (Garbisch et process is generally a continuous one
al. 1975). Groins also attract fishes and since the forces that eroded the beach
often provide excellent fishing spots. initially are probably still at work and
Before a stable shoreline is achieved, will erode it after nourishment. Thus,
scouring and filling around groins af- further nourishment is required at a
fects productivity by keeping the water later date.
turbid and by providing a poor habitat If the purpose of the wider beach
for marine plants and animals (Cronin
et al. 1969, Garbisch et al. 1975). is for protection, there are several
structural alternatives available. A
Cumulative effects. Cumulative ef- breakwater will tend to widen the beach
fects of numerous groins in an area are in its lee. It will also assist in dis-
similar to the summation of effects caus- sipating energy from wave attack, thus
ed by single groins.They are, however, providing protection to structures or
more widespread. Because croins tend land in its lee. If the purpose of the

wider beach is simply shore protection, shore protection in the Gulf of Mexico,
and the wider beach serves no other south Florida, and the south Atlantic
functional purpose, then the upland (Coastal Regions 3, 4 and 5). They are
area can be protected by means of re- rarely completely successful unless they
vetments, bulkheads, or seawalls as are planned as part of an area-wide com-
alternatives to groins. prehensive shore protection program
(Florida Department of Natural Resources
The negative impact most often 1973). They should be constructed only
associated with groins is their tendency where the angle of incidence of waves
to starve downdrift beaches of littoral with the shore is small (Herbich and
sand. An offshore breakwater will have Schiller 1976). The height should be
this same effect so it does not repre- kept low, no more than I ft (0.3 m)
sent an attractive alternative if down- above normal hiah water. They should
drift starvation is to be avoided. Direct terminate at the 3 ft (0.9 m) depth and
armoring of the shoreline by the revet- the length should be no more than 100 ft
ments, bulkheads, or seawalls can have (30.5 m) (Collier 1975). Construction
some effect on shorelines immediately materials on the Florida coastline vary,
downdrift; but the impact will normally but preformed concrete is probably more
be less than that of groins. Of course, commonly used than stone due to the lat-
these structures will have impacts of ter's scarcity in much of the State.
their own which are described elsewhere Groins generally have little effect on
in the report. the biota compared to other larger
structures, such as jetties and break-
A rtifi ci al beach nourishment by waters (Gifford 1977).
dredging or truck hauling from areas of
sand surplus probably represents the Sand-filled nylon bags were used in
most attractive alternative to groins in an experimental aroin field in North
terms of preventing starvation of down- Carolina (Machemehl and Bumgarner 1974).
drift beaches. In fact, beach nourish- They were easily damaged and shortlived,
ment may cause some short term impacts but inexpensive compared to other con-
which can constitute a problem if done struction materials. They were also re-
during periods of recreational uses of latively easy to place.
the beach area.
Groins are common in the middle
Regional Considerations Atlantic (Coastal Region 6). One study
reported 45 such structures in only
No information was found that was 8,400 ft (2,560 m) of shoreline in Ches-
unique to groins in the north Pacific apeake Bay (Schultz and Ashby 1967).
(Coastal Region 1). Rock construction worked most satisfac-
torily and required the least mainte-
Groins are common in those por- nance in this area. Well-ring construc-
tio n s of southern California ( Coastal tion was tried, but proved unsatisfac-
Region 2) where beaches exist. Though tory since some of the rings washed away
permeable groins with removable panels and maintenance requirements were high
are sometimes used (Riese 1971), beach (Schultz and Ashby 1967). Circulation
nourishment is usually required( Carlisle patterns in Chesapeake Bay areas were
1977). Southern California had a large altered by groin placement. This affect-
volume of littoral drift (Berg and Watts ed erosion patterns, as well as nutrient
1971), but it has decreased in recent and sediment accumulation rates in
years due to reduced volumes of sand marshes (Carstea et al. 1975a). When
reaching the sea from the uplands and benthic invertebrate loss and gain due
from loss of sand into offshore subma- to construction of groins were compared,
rine canyons (Carlisle 1977). They also it was estimated that the net effect was
provide a habitat for rocky shore or- neither beneficial nor detrimental (U.S.
ganisms (U.S. Army Engineer District, Army Engineer District,New York 1976).
Los Angeles 1974d). The same document reports that fish will
be attracted to groin areas.
Groins are frequently used as al-
ternatives to seawalls and bulkheads for Groins are common shore protection
43

structures in the north Atlantic (Coast- water areas, there is some confusion of
al Region 7), particularly along the New identification and the same structure
Jersey and Long Island coastlines. No may have different names in different
information unique to groins in this areas.
coastal region was found.
Structure Functions
Groins are used throughout the
Great Lakes (Coastal Region 8) to pro- Bulkheads are built to prevent
tect both shallow and steep, eroding sliding of the land behind the struc-
shorelines. The Michigan Demonstration ture. In this capacity they serve a
Erosion Control Program involves an on- number of diverse functions, such as
going study of the effectiveness of a protection of uplands from erosion,
number of shore protection devices, in- creation of shorefront real estate,
cluding groins (Brater et al.1974, 1975, moorage of vessels, and other aesthetic
Marks and Clinton 1974). Several dif- or recreational uses. However, the uti-
ferent designs and materials are being lity of bulkheads is that they allow
investigated. Some of the designs have protection against waves and currents
proved successful at retarding erosion without loss of land. Thus, one major
while others have failed. A great deal function of the structure is to deline-
has been learned concerning erosion on ate between land and water with no loss
Great Lakes shorelines. Filters are nec- of land area. In many areas bulkheads
essary to prevent undermining or settl- are built along shorelines and then
ing on clay and sand substrates (Marks backfilled to create or reclaim water-
and Clinton 1974). Impermeable groins front land. Bulkheads are often used
are preferable for use in the Great where land is particularly valuable or
Lakes (Lee 1961). Basic design criteria where there is insufficient land avail-
generally differ little from that of the able to provide a sloped surface or
groins in the ocean. One difference is beach for protection.
that B rater (1954) recommends that
they terminate short of the 6 ft (1.8 m) Bulkheads provide a vertical separ-
depth contour for maximum effective- ation of land and water which allows
ness. mooring of vessels adjacent to land
without the necessity of a pier. A
BULKHEADS bulkhead, either alone or in conjunction
with a wharf, is often used for cargo
D efi nitio n handling facilities in ports.

A bulkhead is a structure or parti- Site Characteristics and
tion built to prevent sliding of the land Environmental Conditions
behind it. It is normally vertical, but
may consist of a series of vertical sec- Bulkheads are built parallel to and
tions stepped back from the water and on the shoreline. The location of a
built parallel or nearly parallel to the bulkhead on the shoreline is generally
shoreline. There is no precise distinc- in the vicinity of the mean high water-
tion between bulkheads and seawalls, line, but placement can range from above
although some authors suggest the pri- mean high water to below mean low water
mary purpose of a bulkhead is to pre- depending upon the structure's function.
vent sliding of the land while the pri- For example, when bulkheads are built
mary purpose of a seawall is to protect for boat mooring, the structure general-
the upland area from wave attack (U.S. ly is placed below the mean high water-
Army Corps of Engineers 1973b). Thus, line and the bottom, in front of the
a seawall might project above the eleva- structure, is dredged to allow access at
tion of the upland area, while a bulk- low tides. Bulkheads thus are found in
head would terminate at or below that all tidal zones ranging from subtidal to
elevation. terrestrial. They are generally install-
ed in areas of relatively low wave ener-
Since bulkheads, seawalls, and re- gy because waves will usually cause
vetments are all generally parallel to scour and subsequent structural degrada-
the shoreline and separate land from tion.
44

Bulkheads and seawalls, generally and steepness, beach slope, roughness
built to separate land from water areas, and slope of the bulkhead, and beach
can serve a number of diverse functions sand size (Chestnutt and Schiller 1971,
(see Structure Functions section). They McCartney 1976). In general, structures
are found in many types of coastal hab- which are not vertical and have rouaher
itats including areas with eroding shore- faces, such as revetments or step-ped
lines, narrow fringe marshes, salt and concrete seawalls, tend to reflect less
freshwater marshes, and other areas wave energy seaward and are less affect-
with eroding mud, silt, sand, or shin- ed by toe scour (Coen-Caoli 1932, Pallet
gle beaches. Because bulkheads and and Dobbie 1969, Sanko 1975).
seawalls are expensive to build, they
typically are found in the developed Adequate pile penetration is anoth-
areas where shorefront real estate is er means of preventing undermining of
valuable. bulkheads from toe scour. It also pre-
vents the toe of the structure from
.Placement Constraints sliding seaward (Collier 1975). Sheet
piling must be driven to a depth to
Engineering. A number of factors withstand the outward pressure from ma-
must be considered in bulkhead design terials behind the structure (Ayers and
and construction. Important considera- Stokes 1976). Generally pilings are
tions include height and location on driven to a depth such that at least
beach, toe protection, shape of the two-thirds of the piles are below ground
structure, pile penetration, structural (Michigan Sea Grant Advisory Program un-
anchorage, alignment with adjacent dated).
bulkheads, and erosion of supporting
beach materials from behind the struc- Bulkheads should be securely an-
ture. chored at their ends and along their
length. Adequate tiebacks along the
Many authors recommend that bulk- length of the structure prevent seaward
heads be constructed above the mean tilting (Collier 1975) (Figure 22). Tie@
high waterline for both engineering and back rods should be coated or wrapped to
biological reasons (see Biological Con- prevent corrosion. Both ends of a bulk-
straints section). Bulkhead height and head should be secured to prevent struc-
placement on the shoreline should be tural failure due to erosion of materi-
such that waves do not overtop the als from behind the bulkhead and from
structure and erode away supporting the shore adjoining the structure. Wing
beach material, or saturate the soil and or cut-off walls are two methods of pre-
cause structural failu re due to the venting such erosion and of tying the
buildup of hydrostatic pressures. When structure to the shore (Collier 1975,
bulkheads are located on the shoreline Michican Sea Grant Advisory Program un-
so that they are regularly exposed to dated). in areas where bulkheads are
wave action,the equilibrium of the shore adliacent to each other additional an-
profile is disrupted. The foreshore typ- chorage comes from alignment of the
ically steepens and higher waves reach structures. Irregular alignment of bulk-
the structure causing increased toe heads can cause "side erosion and cavi-
scour and structural damage from un- tation by reflected corner waves" (Bauer
dermining (Earattupuzha and Raman 1975).
1972).
Supporting materials behind bulk-
Toe protection can help prevent heads may be washed away by leaching of
scour at the toe of a bulkhead and also sand through cracks, weep holes, and
protect the structure against changing joints in the structure. Addition of a
beach profiles. Wave energy is deflect- filter cloth to the structure's design
ed as waves break against bulkheads will prevent such erosion and allow wa-
(Figure 21). Wave energy which is not ter drainage(Barrett 1966, Collier 1975,
dissipated by the structure can cause Dunham and Barrett 1974). In areas where
scouring of material at the toe of the the soil has a high silt or clay con-
bulkhead. Important factors in deter- tent, the addition of a 6-inch (15-cm)
mining toe scour include wave height sand pad between the filter cloth and

Z5 V

Figure 21. Waves breaking against the concrete bulkhead bordering the
causeway in Apalachicola Bay, Florida. Photograph by E. L. Mulvihill.

An
74

Oft-A

Figure 22. Wooden sheet pile bulkhead at low tide. The pressure of the emba
caused the top of the structure to tilt seaward. This probably resulted from
quate anchorage and undermining of the structure at its toe. Photograph by T

the soil embankment will help prevent structures (Bellis et al. 1975, Sanko
loss of silt and clogging of the filter 1975).
(Dunham and Barrett 1974).
Biological. When planning bulkhead
Socioeconomic. Bulkheads can se- construction, the effects of the struc-
verely limit recreational activities on ture on the total environment should be
shorelines (Brater 1954). Several au- considered (Committee on Government Op-
thors urge consideration of the effect a erations 1970). Numerous biological con-
bulkhead will have on access to public siderations were found in the literature
beaches prior to construction (Coastal which apply to most coastal regions:
Plains Center for Marine Development
Service 1973, McAllister 1977, Snow
1973). Bulkheads can affect swimming, 0 Bulkheads should be designed
water skiing, diving , fis hin g , and so that reflected wave energy
shellfishing (Carstea et al.1975a; Center does not destroy stable marine
for the Environment and Man, Inc. bottoms (Florida Department of
1971). Borrow areas,which are some- Natural Resources 1973, South
times created to provide backfill mate- Caroline Marine Resource Divi-
rial,may pose a hazard to unsuspecting sion 1974).
waders, swimmers, and fishermen.
0 Bulkhead construction should
The appearance of a bulkhead,both avoid sharp angle turns be
alone and as part of the overall shore- cause this may create flushing
line, is an important consideration. Snow or shoaling problems (Bauer
(1973) advocates designing bulkheads to 1975, South Carolina Marine
blend in with the surrounding shore- Resources Division 1974).
lin e. The South Carolina Marine Re-
sources Division (1974) encourages ap- 0 Bulkheads should be designed
plications for bulkheads that will aes- to minimize damage to fish and
thetically and/or ecologically enhance shellfish habitats (Snow 1973).
the marine environment in areas that
have been extensively developed. This 0 Vertically designed bulkheads,
agency also discourages bulkheads especially when they protrude
which have sharp angle turns because out to minus tide levels in bays
trash may accumulate there. and estuaries, eliminate protec-
tive habitat for salmon fry
Construction and maintenance costs (Stockley 1974). Stair-step de-
are an important determinant of the sign bulkheads or riprap revet-
type of structure built at a given loca- ments on a 45 or less degree
tion. Bulkheads and seawalls are gener- angle provide protective habitat
ally very expensive to construct and for salmon fry (Heiser and Finn
maintain. Initial construction and main- 1970).
tenance costs for the design life of the
project vary, depending upon site con- 0 Toes of bulkheads should not
ditions, geographic region, materials intrude into fish spawning
used, and massiveness and design of beaches (Millikan et al. 1974).
the structure. Initial construction costs
can range from $30.00 to over $500.00 0 Fill material should riot be ex-
per linear foot of protection for more cavated from shallow water and
massive seawalls. Local availability of productive wetlands (Carstea
the suitable construction materials influ- et al. 1976).
ences cost of the structures. The cost
of maintenance depends upon labor ex- 0 When possible, existIng shore-
penses, material costs, and frequency line vecetation should remain
of repair. In general, poured concrete undisturbed and/or enhanced
structures are the most expensive to for use in shoreline stabiliza-
build,with stepped designs more expen- tion (Florida Game and Fresh-
sive than either the vertical or sloped water Fish Commission 1975).

0 Marsh and mangrove edges should used as construction materials in tem-
not be bulkheaded because this porary bulkhead structures to promote
eliminates productive fish and wild- the establishment of shoreline veoeta-
life habitat (Carstea et al. 1976, tion (Webb and Dodd 1976). Other mate-
Silberhorn et al. 1974). rials such as plywood, sheet metal,and
fiberglass panels have limited useful-
0 Bulkheads should be set landward ness (Bellis et al. 1975).
of the mean high waterline because
this allows a buffer strip of shore- Steel sheet piling is a c.*nmonly
line vegetation to remain (Carroll used bulkhead construction material in
undated, Clark 1974). the Great Lakes. About 70% of all bulk-
head projects in the Chicago Corps of
0 Amounts of suspended sediments Engineers District use steel sheet pil-
should be restricted during con- ing (Boberschmidt et al. 1976). Steel
struction (Carstea et al. 1975a). sheet piling, when used to construct
bulkheads, should be interlocked, driven
0 Bulkheads which would adversely into the qround, and tied back for sta-
affect littoral drift and sand depo- bility. @teel corrodes in warrr. moist
sition on barrier and sand islands marine climates and should be protected
and sand beaches are not accept- with plastic, bitumin, concrete, or
able (U.S.Department of the Inte- other suitable materials or should be
rior, Fish and Wildlife Service made of a chemical composition resistant
1975b). to marine environments (Collier 1975).
Cellular steel sheet pile bulkheads are
Vertical wooden, steel, and con- often used in place of sheet pile bulk-
crete bulkheads provide poor habitats heads when the ground substrate cannot
for marine organisms (Gantt 1975). The be penetrated due to rocks near the sur-
other biological considerations may be face (U.S. Army Corps of Engineers
found in the Summary of Physical and 1973b).
Biological Impacts section.
Concrete bulkheads are commonly
Construction Materials used in Florida and other more tropical
climates due to their durability in com-
There are two structural classes of parison to steel or timber structures
bulkheads. Massive freestanding gravity (Gantt 1975). Concrete bulkheads may be
structures, sometimes called seawalls, vertical, sloped, concave, convex, or
make up the first class (Figure 23). stair-stepped. They are, generally,
Seawalls have two functional compo- either cast in place or constructed of
nents, the stem and the base. The stem concrete slabs with a cast-in-place con-
of the structure may be curved, verti- crete cap (Figure 24).
cal, or inclined and is designed to with-
stand the full force of oncoming waves. Wood is the most popular type of
The stem generally is constructed of construction material (Ficures 25 and
rubble or concrete. The base often in- 26). The timber should be treated with
cludes foundation piles which support a wood preservative in warmer areas
the structure and prevent settling, and where decay and rot, insects, or marine
sheet pile cut-off walls which help to borers pose a problem (Collier 1975).
prevent loss of foundation material (Col- The components of timber sheet pile
lier 1975,U.S. Army Corps of Engineers bulkheads usually include piles, walers,
1973b). sheet piles, tie rods, and deadmen or
anchor piles (Figure 27). Piles are
The second class of bulkheads is driven or jetted into the beach, and
constructed either of concrete slabs or walers are bolted horizontally to the
sheet piles that are driven into the landward side of the piles. Tie rods
ground and anchored by tie rods. Con- are also secured to the piles and at-
struction materials include steel, con- tached to anchor piles or deadmen behind
crete, timber, or combinations of these the structure. Timber sheet piling is
materials. Pipes, cables, tires, wire bolted or nailed to the walers. Piles
netting, and baled hay have also been and walers are generally made of heavy

Figure 23. Concrete seawall in Florida. Note
signs of wave damage to the base of the structure.
Photograph courtesy of Florida Department of
Natural Resources.

Figure 24. Concrete bulkhead on Fidalgo Island,
Washington. Photograph by T. Terich.

Figure 25. Bulkhead constructed of a series of
wood piles. Photograph by C. A. Francisco.

Figure 26. Wooden sheet pile bulkhead along the
Gulf coast of Florida. Photograph by E. L.
Mulvihill.

SHEET PILE

*-z-PILE
BACKFILL FILTER--*, WALER
CLOTH
ORIGINAL SLOPE IE ROD/ 4

DESIGN WATER LEVEL

DEADMAN TOE PROTECTION

FILTER CLOTH

Figure 27. Side view of a typical sheet pile bulkhead. Dimensions and details to be determined by
T

FILTER CLOTH

particular site conditions.

tim be r. Tie rods (sometimes referred jetting piles and sheet piles, placing
to as tie backs) when made of steel and securing tie rods and anchors, and
cable should be coated or wrapped to backfilling behind the bulkhead. These
prevent corrosion (Collier 1975). Tie activities require a truck for material
rods function to prevent seaward tip- transport, a bulldozer, a pile driver or
ping of the bulkhead and must be se- pile jetting equipment,a crane for lift-
curely anchored. Anchors typically are ing heavy piles, anchors, and walers,
deadmen (horizontally placed timbers), and dredging equipment if fill material
anchor piles,or concrete anchor blocks. is obtained by dredging. Other types of
bulkheads require similar equipment.
Construction materials used for toe
protection and filters are similar to This heavy equipment causes noise
those used for revetments. and air pollution at the site. Carstea
et al. (1975a) maintain that air pollu-
Expected Life Span tion, resulting from construction of a
150 ft (45 m) timber bulkhead, should be
The expected life span of bulk- well below Federal air quality standards
heads ranges from 10 yr to approximate- and that noise will have an effect on
ly 30 yr. Life span is site specific and areas within about 200 ft (61 m) from
will depend upon location of the struc- the site. However, construction noise
ture on the beach, design wave height may be sufficient to disrupt waterfowl
and period, construction materials, and which way be nesting or resting at or
climatic conditions. near the site.

Timber and steel sheet pile bulk- Fish and wildlife habitat is dis-
heads have shorter life spans in warmer rupted and/or lost due to construction
climates. Deterioration of wooden struc- activities. Damage to fish and wildlife
tures from decay, insects, and marine resources depends upon the type of hab-
borers is accelerated, as is the corro- itat in the area prior to construction,
sion of steel structures. Collier (1975) where the structure is placed on the
related one instance in Florida where a shoreline, its size, and construction
temporary wood work trestle, built from methods. The bulkhead and associated
450 untreated pine piles, was rendered backfilling bury established terrestrial
unsafe for work after only 3 mo of ser- and intertidal flora and fauna. The
vice due to shipworms. The life span heavy equipment used during construction
of steel structures may be less than 10 disturbs vegetation behind the structure
yr in warm marine environments if the (Knutson 1977). In areas where bulkhead-
steel is not coated or of a resistant ing and backfilling are used to create
chemical composition (Collier 1975). shorefront real estate, bulkhead con-
struction impacts represent the first
Very little data are available to step in a chain of events which lead to
assess the actual durability of various larger losses due to land development
bulkhead types. However, several au- behind the bulkhead. Benthic habitat,
thors have pointed out that bulkheads in addition to terrestrial and inter-
do not provide a long-term permanent tidal habitat, is also lost if dredging
solution to shoreline erosion because the is used to obtain fill material or to
beach will continue to recede (Coastal create a channel up to the bulkhead.
Plains Center for Marine Development
Service 1973, U.S. Army Corps of Eng-
ineers 1964, 1971b). This recession may Construction activities will cause
even be accelerated as a result of wave local erosion and new sediment deposits
reflection from the bulkhead(Figure 28). in the vicinity of the bulkhead due to
disturbance of bottom sediments during
Summary of Physical and Biological dredging, pile driving or jetting, and
Impacts backfilling. New sediment deposits are
often silty and can destroy spawning
Construction effects. Construction areas, smother benthic organisms, and
of sheet pile bulkheads involves trans- reduce bottom habitat diversity and food
porting materials to the site, driving or supply (Carstea et al. 1975b).
53

4TI

NE,
I

Figure 28. Old bulkhead line on a beach that has continued to erode in
Skunk Bay, Washington. Photograph by C. A. Francisco.

Several authors have pointed out absorbing tidal marshes with impermeable
that disturbance of substrate and ero- bulkheads (Gosselink et al. IP73, King
sion during bulkhead construction leads 1972). A bulkhead restricts movement of
to turbidity and water quality degrada- sand to and from beach and dune areas
tion (Boberschmidt et al. 1976, Carstea (Georgia Department of Natural Resources
et al. 1975a, 1976, Environmental Qual- 1075, Gifford 1977). This, coupled with
ity Laboratory, Inc.1977, Gantt i975, ongoing reflected wave energy from bulk-
U.S. Army Engineer District, Baltimore heads, inhibits the recovery of sedi-
1975,Virginia Institute of Marine Science ments to storm eroded beaches.
1976). However, biological impacts from
tu rbidity and changes in water quality Bulkheads may also promote erosion
have not been well documented. Con- of adjacent beaches (Bellis et al. 1975,
stru ctio n activities w hic h cause the Carstea et al.1@75a, Gantt 1975, Georgia
greatest increases in tu rbidity are Department of Natural Resources 1975,
dredging and filling, and pile driving Herbich and Schiller 10,76, Pallet and
or Jetting. Resuspension of bottom sed- Dobbie 1969,U.S. Army Engineer District,
iments from these and other construc- Baltimore 1975). Erosion of adjacent
tion activities may release trapped nu- beaches may be accelerated until a new
trients, heavy metals,and other toxic geohydraulic equilibrium is reached.
substances into the water. Suspended This erosion may result from alterations
sediments reduce light penetration in water circulation patterns or from
which may lead to a temporary decrease the structure intruding into the litto-
in primary productivity. Suspended ral zone and obstructing littoral drift
materials also may interfere with respi- (Bauer 1975, Carstea et al. 1975a, Gantt
ratory and feeding mechanisms of the 1975, Georgia Department of Natural
fishes, zooplankton, and benthic organ- Resources 1975).
isms.
Bulkheads, like revetments, can af-
Chronic effects. Bulkheading has fect the plant and animal communities in
often been described as a relatively im- the upper foreshore and backshore zones.
permanent means of separating land Bulkheads, constructed in wetland areas,
from water, especially in areas where can cause extensive damage to fish and
the shoreline is eroding (Coastal Plains wildlife habitat. Construction and asso-
Center 'for Marine Development Service ciated backfilling destroy wetlands by
1973, U.S. Army Corps of Engineers covering up narrow fringe marshes, by
1-064, 1971b, Warnke 1973). Bulkheads, covering up the waterfront edge, and by
like revetments, protect upland areas altering water circulation in larger
directly behind the structure from the shorefront marshes. Wetlands are highly
eroding action of waves and currents. productive areas which filter upland
However, they do not protect adjacent runoff and function as nutrient and sed-
beaches or the foreshore. iment traps. Destruction of shorefront
wetlands eliminates waterfowl feeding,
A bulkhead often promotes erosion nesting, and resting habitats and de-
of the foreshore (Bauer 1975, Bruun stroys the habitat for other birds, rep-
and Manohar 1963, Coastal Plains Center tiles, and small mammals (Boberschmidt
for Varine Development Service 1973, et al. 1976, Carstea et al. 1975a,
King 1972, Massachusetts Coastal Zone Herbich and Schiller 1976).
Management Program undated a, Pallet
and Dobbie 1969, Schultz and Ashby The construction of a bulkhead
1967, Slaughter 1967, U.S. Army Corps eliminates much of the intertidal zone.
of Engineers undated). Erosion of the If the structure is built below the mean
foreshore is caused by an increase in high waterline, it eliminates the tran-
v@ave energy due to waves reflecting off sition zone between the intertidal and
the face of the structure (Figure 21). adjacent subtidal areas. This region is
the most productive zone in estuaries
Foreshore erosion is p a rtic ula rly (Lindall 1973, Odum 1970, Stockley
severe during storms. Damage inland 1974). This transitional zone, replaced
from hurricanes and storms often is in- with a vertical bulkhead, provides lit-
creased due to replacement of energy tle productive habitat. At most a wooden

bulkhead provides a new habitat for a and natural estuarine habitats have
few sessile and marine boring organ- shown natural areas to be more produc-
isms, such as barnacles , hydroids, tive (Mock 1966, Trent et al. 1976).
gribbles, and shipworms. These differences have been attributed
to low abundance of organic detritus and
The newly created deep water zone benthic macroinvertebrates, deeper wa-
in front of a bulkhead often has a lower ter, and loss of intertidal vegetation
concentration of detritus, lower phyto- in bulkheaded areas.
plankton production, and fewer benthic
organisms than adjacent unbulkheaded Bulkheads also can affect fish
areas (Massachusetts Coastal Zone Man- spawning, feeding, and nursery habitat.
agement Program u n dated b, Odum For example, bulkheads have been shown
1970). The turbulence and scouring to alter salmon fry behavior in Puget
action in front of bulkheads from re- Sound, Washin ton (Heiser and Finn 1970,
flected wave energy often prohibits Stockley 1974T Vertical bulkheads cause
vegetation from reestablis hin g (Gantt an abrupt habitat change with few shal-
1975, Knutson 1977) and may destroy low water areas. Salmon fry tend either
existin g grass flats (Gifford 1977). to go out into deeper water when con-
fronted with a bulkhead or to concen-
Ellifrit et aL (1972) studied clam trate near bulkheads and not go around
populations in bulkheaded and adjacent them. Both circumstances make salmon
natural areas in Hood Canal, Washing- fry extremely vulnerable to predation.
ton. Twice as many clams were found Stair-step design bulkheads or riprap
on natural beaches at three out of the revetments on a 45 or les,s degree angle
four sites studied. At two sites signif- were found to provide protective habitat
icantly more Japanese littleneck clams, for salmon fry (Heiser and Finn 1970)
Venerupis Japonica, were found in up- In another study, (Millikan et al. 1974@
per intertidal regions. Differences in bulkheads extending down below the mean
size and distribution were noted. Clams high waterline were found to bury and
in the lower intertidal regions appeared destroy smelt spawning substrate in
unaffected by bulkheads. The authors Puget Sound and Hood Canal, Washington.
concluded that these differences pro- As a result of this study, State bulk-
bably were due to changes in current head criteria for surf smelt spawning
patterns as sociated with bulkheads. beaches were modified to protect upper
Bulkheads appeared to produce less fa- intertidal and sand-fine gravel beach
vorable conditions for settling and sur- areas.
vival of clam larvae and may have caus-
ed reduction in availability of nutrients Cumulative effects. Physical and
and food. biological impacts from the construction
of a number of bulkheads in a coastal
Moore and Trent (1971) studied area may have a cumulative effect, how-
settling, growth,and mortality of oysters ever, no pertinent studies were found.
in two areas in West Bay, Texas. The Irregular alignment and patchy bulkhead-
first area was a dead end canal that ing along a shoreline often create ero-
had been created by dredging, bulk- sion pockets between bulkheads on natu-
heading, and filling of a coastal marsh. ral beaches (Bauer 1975). Extensive
The second area was a dead end bayou bulkheading of wetlands on the shores of
in an unaltered part of the same marsh. estuaries and bays can severely reduce
The settling of oysters was 14 times fish and wildlife habitat and impact es-
greater in the natural marsh than in tuarine related fisheries of a whole re-
the canal area. Faster growth rates gion, as well as waterfowl populations.
and lower annual mortality rates charac- For example, Lindall (1973) identified
terized oysters in the natural marsh. bulkheading of south Florida's estuarine
The authors attributed these differences shorelines and the resulting destruction
to the poor water circulation, plankton of the nursery grounds as a threat to
blooms, low levels of dissolved oxygen, the estuarine-dependent fisheries (about
and high nutrient levels in the canals. 85% of the area's commercial fisheries)
of that region. Clearly, examination of
Studies of shrirnp in bulkheaded the physical and biological impacts of

bulkhead construction on a case-by-case and the, consequent loss of variable
basis ignores a' host of potential cumula- depths and intertidal zones which exist
tive physical, chemical, and biological on natural shorelines. The alternatives
impacts (Fetterolf 1976). which best protect these features are
either beach nourishment to maintain a
Structural and Nonstructural Alterna- natural-like shoreline or revetments. A
tives revetment will provide protection to a
specific site and, if designed properly,
The design of bulkheads can be al- will allow variable depths and inter-
tered, or they can be used in conjunc- tidal zones to be retained.
tion with other structures, to modify
their impact. Bulkheads can be stepped Regional Considerations
back in a series of low vertical walls
which will provide some variation in Along the north Pacific coastline
depths in front of the structure. When (Coastal Region 1), bulkheading is most
enough steps are provided, the struc- frequently encountered in Puget Sound.
ture becomes a revetment. (There is Bulkheads have been shown to alter sal-
no exact definition which differentiates mon fry behavior in Puget Sound, Wash-
a stepped bulkhead from a revetment.) ington, and in the Columbia River estu-
Another alternative is to use a bulkhead ary (Heiser and Finn 1970, Stockley
landward of mean high water to protect 1974). Vertical bulkheads often elimi-
u plan ds from higher wave conditions nate shallow water regions, and salmon
and use a sloping revetment or vegeta- fry behavior in the vicinity of such
tion to protect the foreshore or inter- structures makes them extremely vulner-
tidal area. able to predation. Stair-step design
bulkheads or riprap revetments on a 45
The alternatives must correspond or less degree angle were found to pro-
to the intended function of the struc- vide protective habitat for the salmon
tu re. If the function of the bulkhead fry (Heiser and Finn 1970). Another con-
is to protect the backshore land area cern in Puget Sound and vicinity is the
and prevent sliding, an alternative destruction of surf smelt spawning hab-
structural solution is to build a revet- itat by bulkheading spawning beaches.
ment. Offshore breakwaters can also State bulkhead criteria for surf smelt
be used to reduce the wave attack on spawning beaches were recently modified
the land. Buildin up the beach (to to protect upper intertidal sand-fine
protect the uplandsl by groins or beach gravel beach habitat (Millikan et al.
nourishment is also an alternative to 1974).
bulkheads. Another alternative is to
let the land erode and move or abandon Bulkheads built at the bottom of
upland structures. (See also Revet- sea cliffs are one attempt to control
ments. cliff erosion in southern California
(Coastal Region 2). They frequently are
If the bulkheading is needed to found in conjunction with small boat
achieve a vertical interface between wa- harbors in this region. Areas of the
ter and land, then alternatives must re- Gulf of Mexico (Coastal.Regions 3 and 4)
spond. to the need for the vertical in- have been extensively bulkheaded. In
terface. If the vertical face is for moor- Mississippi, from Biloxi Bay westward,
ing vessels, the same function can be including the eastern half of Hancock
achieved by building a pier at right County, the entire shoreline has been
angles to the shore or placing mooring altered by bulkheading and artificial
buoys offshore. If the vertical interface beach nourishment (Virginia Institute of
is needed for recreational or aesthetic Marine Science 1976). Bulkheads are also
purposes (to allow people to get close prevalent along the Atlantic coast
to the water), a pier or structure pro- (Coastal Regions 6 and 7). They are
jecting into the water presents a logical found almost continuously along northern
alternative. New Jersey shorelines (Yasso and Hartman
1975).
The predominant criticism of bulk-
heads relates to their vertical design A common practice in Galveston Bay,
Texas, and in southern Florida (Coastal
57

Regions 3, 4, and 5) has been to build REVETMENTS
bulkheads along vegetated shorelines
and then to ba@kfill the area to create Definition
wat-2rfront real estate (Lindall 1973).
The natural shoreline is usually altered A revetment is a sloped structure
by channelization, bulkheading, and fill- built to protect existing land or newly
ing. Houses are built on narrow strips created embankments against erosion by
of land' which are separated by a series wave action, currents, or, weather. Re-
of dead-end channels (hence the name vptments are usually placed parallel to
"finger-type" development). The biolog- the natural shoreline. Riprap (randomly
ical effects of this type of development placed stones) and gabions (a wicker-
in bays and estuaries have not been like basket which can be filled with
well researched. However, several stud- stones) can be included in this defini-
ies do give some indications of potential tion.
impacts. Physical chances in estuaries
and bays include: reduction in acreage Structure Functions
of shore and marsh vecietation, chanoes
in marsh water circulafion patterns a-nd The primary function of most revet-
nutrient input into the bay or estuary, ments is to protect the area landward of
changes in water depth and substrates, the revetment from erosion or scour due
and the conversion of aquatic areas to to waves or currents. This protection
upland areas with a resulting decrease is due to the armoring characteristics
in water area in the bay or estuary of the revetment and its ability to dis-
(Corliss and Tre'nt 1,071, Cronin et al. sipate wave energy. Revetments are nor-
1971). mally used where it is necessary to re-
tain the shore in a more seaward posi-
The ecology of one finger-type tion relative to adjacent lands, where
housing development in W est Bay, there is little or no protective beach
Texas, has been studied extensively. in front of the land to be protected, or
Phytoplankton production (Corliss and where it is desired to maintain a cer-
Trent 1971, Trent et al. 1976), sub- tain depth of water in front of a struc-
strates, and hydrology (Trent et al. ture. Revetments are especially useful
1976)were studied in an open bay area, at the mouths of waterways where erosion
in a bulkheaded canal area in the de- is frequently severe (Coastal Environ-
velopment, and in an adjacent natural ments, Inc. 1976). They may also prevent
marsh area. In oeneral, productivity undermining from wave erosion when plac-
was higher in the marsh than in canal ed along the seaward slope of eroding
areas and lowest in the open bay. The dunes or cliffs (Yasso and Hartman
plankton blooms followed by low levels 1975). Revetments are often used to pro-
of dissolved oxygen, high nutrient lev- tect the foundations of structures, such
els, fish kills, and lowered production as bulkheads or buildings (Figure 29),
of oysters, benthic macroin vertebrates, from erosion. Figures 30 and 31 give
and shrimp in summer months indicated examples of riprap and concrete revet-
the presence of eutrophic conditions in ments. Revetments are generally used
the canal areas of the housing develop- where there is the potential for high
ment. Similar eutrophic conditions have wave energy. Bulkheads can function in
been reported in housing developments a similar capacity, but offer far less
in Florida (Lindall 1973, Taylor and energy dissipation.
Saloman 1968). T rent et al. (1972)
noted that standing crops of benthos, Site Characteristics
fis h, and crustaceans were relatively
high in the canal areas in spite of ap- Revetments are c!enerally built to
parent eutrophic conditions. The au- protect eroding shorelines. They are
thors were unsure if this was due to found in many types of coastal habitats
canal areas in the housing development including areas with eroding embankments
being self-supporting in terms of vege- or cliffs and little or no protective
tative production or whether productiv- beach. Their most common occurrence is
ity relied upon the detritus carried in in developed areas where the shorefront
from the adjacent marsh by tidal action. property is endangered by erosion.

AA6

it,

A
Ji@

ORR,

Figure 29. This riprap revetment functions to limit erosion of the
parking lot at the Kingston, WashingtoN ferry terminal. Picture was
taken at low tide. Light and dark colored bands on the revetment are
due to biological zonation. Photograph by C. A. Francisco.

Afm

A
M? A,
-N@41
7M

@v R,

Idd

C71

0 AN
HEEP (1119
THE ROCAS

Figure 30. Riprap revetment protects the U.S. Coast Guard Light Station at Point
No Point, Washington. Large drifting logs, such as the ones pictured in the fore-
ground, make the use of gabion revetments impracticable in much of Puget Sound.
Photograph by C. A. Francisco.

@, -e5

Figure 31. Concrete revetment along U.S. Highway 98 in the
vicinity of Port St. Joe, Florida. Note the toe protection
at the base of the revetment. Photograph by E. L. Mulvihill.

Conventional revetments typically Toe protection is necessary to pre-
provide protection from well above the vent scouring at the base and to protect
mean high water line to well below the the structure against changing beach
mean low water line. Conventional re- profiles. Revetments possess very little
vetments thus extend from the terres- internal stability, relying on the un-
trial zone to the subtidal zone. Upper derlying beach which they protect (Fig-
beach revetments extend from above the u re 32). Undermining of the structure
mean high water line to an area between at its toe can lead to -failure of the
the mean high water line and the mean entire structure. Wave energy is de-
low water line. This type of revetment flected both landward and seaward as
generally lies within the region extend- waves break against revetments. Wave
ing from middle intertidal zone to the energy which is deflected seaward can
terrestrial zone. Revetments can also cause scouring of material at the foot
be used entirely above the mean high of revetments (U.S. Army Corps of Engi-
water line for protection against storm neers 1973b). Factors affecting the
generated tides. Revetments are usual- amount of toe scour include slope, per-
ly constructed parallel to the natural meability and roughness of the revet-
shoreline. ment, water depth, hypothetical surface
of wave reflection, wave height and
Placement Constraints steepness,and beach sand size (McCartney
1976, Sato et a]. 1968).
Engineering Several factors should
be considered when evaluating the de- In ceneral, rougher, flatter, and
sign of a revetment. Design considera- the more permeable revetment surfaces
tions include design life of structure, cause less toe scour and require less
design wave, seasonal changes in beach toe protection. Structural failure due
profile, water level range (e.g. changes to scour may be avoided by incorporating
due to tides, storms, and for the Great adequate toe protection into the design
Lakes seasonal lake level), beach compo- of revetments. Common toe protection
sition,and beach use (McCartney 1976). methods are addressed in the construc-.
Once these site conditions are known, tion materials section.
alternate types of revetments may be
evaluated. Armor facing requirements, The supporting materials under
wave runup heights, toe scour depth, structures may also be washed away if an
toe protection needs, revetment slope, adequate filter is not used. A filter
revetment length, and filter require- prevents undermining of the revetment,
ments vary with different types of re- distributes armor unit Weight, and pro-
vetments. vides for relief of hydrostatic pres-
sures (Collier 1975, McCartney 1976).
Revetment slope length and place- Ideally, a filter layer prevents scour-
ment on the shoreline should be such ing of supporting shore material and al-
that waves do not overtop the structure lows water drainage. The amount and type
and erode away the supporting beach or of filter material needed is determined
saturate the soil and cause structural by beach composition, water depth, type
failure due to the hydraulic processes. of armor units, and current velocities.
Wave runup, an important factor in the In areas of heavy wave action, armor
determination of revetment slope length, units are often placed on a scour pad of
depends upon water depth at the toe of plastic filter material (filter cloth)
the structure, slope of the beach in and stone. Special care must be taken
front of the structure, and the slope, in design and construction of imperme-
shape, roughness, and porosity of the able revetments to prevent excessive
revetment (U.S. Army Corps of Engi- landward hydrostatic pressure. Design-
neers 1973b, McCartney 1975). Other ing the structure with gravel or with
factors which determine revetment slope rock weep holes are ways to help prevent
length include water level range, beach this potential problem (McCartney 1976).
slope, toe scour depth, and minimum
water depth allowed at the toe of the Materials used for armor facings
structure (McCartney 1976). should be designed to remain intact

141 ALA
IM
pw

AN*

'Vry

Figure 32. Failure of this interlocking concrete block
revetment was primarily due to settling and erosion of
supporting beach material. Due to its flexibility, this
structure still affords some protection. Photograph
courtesy of Florida Department of Natural Resources.

under anticipated environmental condi- or concrete slabbing because of their
tions. Armor facings constructed of resemblance to the natural stonework
materials such as riprap or rubble (Docks and Harbor Authority 1965). A
should have components which are rock revetment which was to be built at
dense and heavy enough not to be mov- Sunset Cliffs, San Diego County, Cali-
ed by waves. Revetments with perme- fornia, was viewed as more aesthetically
able armor units (such as gabions) or acceptable than a more formal structure
interlocking armor units rely less on (U.S. Army Engineer District,Los Angeles
mass of the individual structural compo- 1970). Bellis et al. (11375) point out
nents to withstand wave energy than do that "the availability of 'free' mate-
more solid type revetments (Docks and rials such as demolished buildings, old
Harbor Authority 1965). More detailed tires, Junked cars, and other debris all
discussions of the various types of ar- too often leads to really bizarre shore-
mor units, their advantages and disad- lines..." An example of such a shore-
vantages, are found in the Shore Pro- line is found in Figure 33. Some au-
te ctio n M a n u al (U.S. Army Corps of thors, however, view any type of revet-
Engineers 1973b) and the Survey of ment as an artificial intrusion that is
Coastal Revetment Ty p es (McCartney an aesthetic affront to the shore envi-
1976). ronment. Ba *uer (1975) made the following
comment with reference to riprap revet-
Socioeconomic. Social and economic ments:
considerations can affect the location
and type of structure built at a site. "The most negative feature of rip-
Local laws, costs of structural alterna- rap, however, resides in the of-
tives, historical points of interest, cur- fending visual impact and environ-
rent and future uses of the area, and mental degradation of the shore
aesthetic values are some of the criteria resource. The use of such rock
which influence the placement of a re- heaps, Just as in the case of the
vetment. Current and future uses of streambank revetments, has now
an area help to determine the need for mushroomed into a serious shore
a revetment at a given location. Beach despoilage - a syndrome that is
use influences the type and location of lining our beautiful beach environ-
the structure on the shoreline. ments with ugly, incompatible bor-
ders and backdrops of rubble."
The design life of a temporary re-
vetment to protect an exposed embank- Economic feasibility often deter-
ment during construction activities mines the number and types of structural
would be shorter than the design life of alternatives available for a given loca-
a revetment built to protect a shore- tion. Initial construct-ion and mainte-
front dwelling from damage due to nance costs for the design life of the
beach recession. Revetments can se- proJect vary depending upon site condi-
verely affect waterfront recreational tions, qeographic region, and materials
activities, such as swimming, boating, used. Initial construction costs can
and shell-fishing. McCartney (1976) range from $25.00 to $200.00 or more per
points out that a beach used "for re- linear foot of protection. While revet-
creation and other purposes may dictate ments tend to be less expensive than
use of upper beach revetment to contain bulkheads, those constructed along the
runup and sandfill on the beach face open coasts or to protect barrier beach-
seaward of the revetment." es are expensive to build and maintain
relative to those built in semiprotected
Several authors have commented on and protected environments. Local avail-
the visual impact revetments have on ability of the suitable construction
the shoreline. Structures which resem- materials influences cost of the struc-
ble and follow the natural shoreline ture. The cost of maintenance depends
seem to have less adverse impact on the upon the labor expenses, material costs
scenic or aesthetic values of an area. and frequency of repair. For example,
For example, gabions are sometimes nylon bag and polyethylene tube revet-
viewed as a more aesthetically pleasing ments are relatively inexpensive to in-
type of revetment than either brickwork stall, but may be expensive to maintain.

.01

1-77@

Figure 33. Pictured is a junk car revetment in Florida.
Due to corrosion, the life span of car body revetments
generally is less than 5 years in brackish water. There
are also aesthetic considerations regarding this type of
revetment. Photograph courtesy of Florida Department of
Natural Resources.

Sandbags and tubes may easily be cut pour the concrete. A concrete revet-
open by vandals (Marks and Clinton ment is depicted in Figure 34. Compo-
1974) and deteriorate quickly, thus re- nents of armor unit revetments include
quiring frequent repair. an armor face, filter, and protective
toe (McCartney 1976)-.
Biological. The Buffalo Army Engi- The armor face is the outer layer
neer M-E-trict (U.S. Army Engineer Dis-
trict, Buffalo undated a) in issuing a of the structure which serves to dissi-
general permit for shore protection in pate wave energy as waves are deflected
Lake Erie listed several biological con- landward. Materials commonly used as
straints on the revetment construction armor facing are shown in Table 2
which may be applied to all coastal re- (McCartney 1975, 1976; U.S. Army Corps
gions: of Engineers 1973b). Riprap revetments
are illustrated in Figures 30 and 31. A
0 Armor unit revetments should Nami ring revetment and an interlocking
be made of clean, non-pollut- concrete block revetment are shown in
ing material. Any material Figures 35 and 36.
contaminated with grease,
phenol, lead, or other toxic A filter serves as an interface be-
elements should not be used. tween the armor facing and the native
soils which the structure protects. Some
0 Revetments should not be commonly used filters include gravel,
constructed during the fish quarry spalls, filter cloth, and combi-
spawning periods. nations of gravel and a filter cloth,
and quarry spalls and a filter cloth.
0 Revetments should not be
constructed in wetlands; in Toe protection is necessary to pre-
areas serving as habitat for vent scouring at the base of revetments
threatened or endangered and to protect the structure against
s pecies; in im porta nt fis h changing beach profiles in front of the
spawning areas; or in signi- structure. Common types of revetment
ficant waterfowl or shorebird toe protection include aprons which will
nesting, feeding, and resting sag into any scour hole that develops,
areas. buried toes, toes weighted with extra
layers of armor units (armor units are
Revetments with facings that are not necessarily the same as those used
highly irregular (such as riprap) and on the rest of the structure), flexible
have a shallow slope have a greater abi- mats such as gabions or filter cloth
lity to support marine life (Gantt 1975). filled with sand, bag or rock sills
Although revetments do provide a new placed seaward of the toe to trap sand
irregular habitat which does support and bury the toe, sand or gravel stock-
greater marine life than vertical sea piles, cutoff walls, and anti-erosion
walls, there is an initial loss of organ- rings (McCartney 1976).
isms and habitat by placement of revet-
ments. Expected Life Span

Construction Materials The expected life span of revet-
ments rances from 5 to 30 yr or more.
There are two structural classes of Expected life span will vary depending
revetments (U.S. Army Corps of Engi- upon construction materials, the wave
neers 1973b): rigid, cast-in-place, and height and period the structure was de-
flexible or articulated armor unit revet- signed to withstand, and the climatic
ments. Rigid, cast-in-place types of conditions to which the structure is ex-
revetments are constructed of cement, posed. Damage to rubble-mound structures
asphalt, or bitumen grouted stone. A is generally progressive, and the Shore
concrete revetment is very effective Protection Manual (U.S. Army Corps of
against wave attack, but water must be Engineers 1973b) recommends considering
removed from the construction area to both the frequency of damaging waves and

RMOR FACING

FILTER
LAYER
DESIGN WATER LEVEL

FILL MATERIAL

TOE
&%'@PROTECTION

BEACH SLOPE

Figure 34. Profile of a revetment. Construction materials, dimensions and details are determined by
particular site conditions. %

Table 2. Types of revetment armor facings.

TaU _r@@ _1 Fa_t7@@i a I s Manufactured units Other materials

Riprap Gabion (stacked or mat) Rock overlaying a thin layer
Uniform rock overlay Woven wire fence mats filled of asphalt
Veaetation with rocks, bricks', sand- Tires filled with sand cement
bags, etc. Nylon fabric mat, bags, or
Cast concrete armor un4lts tubes filled with concrete,
(tribars, tetrapods, sand, etc.
dolosses, quadripods, Stairstep sand cement lifts
etc.) Fiberglass, steel, or aluminum
Interlocking concrete blocks, mat
(lok-gard, shiplap blocks Nylon filter cloth
etc.) Rubble (dumped concrete, asphalt,
00 Gobi blocks bricks, building blocks, etc.)
Concrete cellular blocks Automobiles
Cinder or concrete building
blocks
Nami rinqs

Figure 35. A Nami Ring revetment was constructed in 1974 at
Little Girls Point on Lake Superior as part of the Michigan
State Demonstration Erosion Control Program. Damage to this
structure was extensive after two years of service. Photo-
graph courtesy of the Michigan State Department of Natural
Resources.

"@AMTI
A611V

Figure 36. An interlocking concrete block revetment forms a
checkerboard pattern on the shoreline. Vertical structure at
top of revetment is a reinforced concrete wave screen. Photo-
graph courtesy of Portland Cement Association.

the costs for installation, protection, Habitat is lost due to the struc-
and maintenance when selecting the de- ture being placed over the previously
sign wave. On the Atlantic and Gulf existing substrate (Gantt 1975). Estab-
coasts of the United States, hurricanes lished intertidal flora and fauna are
may provide the design wave criteria; often buried during the revetment con-
whereas on the north Pacific coast, it struction (Coastal Plains Center for Ma-
may be provided by annually occurring rine Development Service 1973). All
severe storms (U.S. Army Corps of plant and animal communities from behind
Engineers 1973b). It may not be econom- the revetment to beyond the revetment
ically feasible, however, to design a toe are therefore affected by the con-
structure which will withstand a hur- struction of revetments. However, in
ricane which may occur once every 20 many cases, such as the construction of
to 100 yr. Structures located in areas riprap revetments, a new and different
with frequent storms should be built to type of habitat is created.
withstand the storms and to avoid high
annual maintenance costs. McCartney Construction activities will cause
(1975) selected the relatively short de- local erosion and new sediment deposits
sign life of 5 to 10 yr for the upper in the vicinity of the revetment (Orto-
beach revetments discussed in his lano and Pill 10,72). This will occur
stu dy. This design life is economical from disturbance of bottom sediments and
and "compatible with erosion p rotectio n erosion of exposed substrate. New sedi-
needs for high lake levels in the Great ment deposits are often silty and can
Lakes" (McCartney 1975). Gantt (1975) "destroy spawning areas, smother benthic
has described riprap revetments,if cor- organisms, and reduce bottom habitat di-
rectly designed and constructed, as be- versity and food supply" (Carstea et al.
ing relatively permanent structures. 1975).
However, very little quantitative data
are available to assess the actual dura-
bility of riprap or other revetment Several authors noted that distur-
types. bance of bottom sediments and erosion
results in increased turbidity and water
Summary of Physical and Biological quality degradation (Boberschmidt et al.
I m pacts 1976; Carstea et al. 1975b; U.S. Army
Engineer District, Buffalo undated a;
Construction effects. Construction Virginia Institute of Marine Science
of revetments involves transporting ma- 1976). Resuspension of bottom sediments
terials to the site, preparing the em- may release trapped nutrients, heavy
bankment to be protected, laying filter metals, and other toxic substances into
materials, placing armor units, and pro- the water column. Suspended materials
viding toe protection. These activities can also interfere with respiratory and
involve a truck for material transport feeding mechanisms of aquatic organisms.
and a front-end loader for construction. The extent of impacts from construction
This heavy equipment causes noise, vi- activities has not been well documented.
bration, and air pollution at the site. The type of revetment, 'its location on
Carstea et al. (1975a) noted that con- the shoreline, construction methods, and
struction time is relatively short for type of substrate all play a role in de-
structures such as riprap revetments. termining construction effects. For ex-
'They also commented that air pollution ample, turbidity from construction ac-
is well below Federal air quality stand- tivities is greater and lasts longer in
ards and that noise from construction areas with finer sediments (Carstea et
activities will only have an effect on al. 1975a). Even with a fine grain type
areas within about 100 ft (30 m) of the of substrate, riprap revetment construc-
site. However, construction noise and tion should not lead to levels of the
activity may be sufficient to disrupt resuspended sediments which exceed those
waterfowl which may be nesting or rest- required for the protection of aquatic
ing at or near the site. Construction life (Carstea et al. 1975a). The effects
activities also disrupt vegetation direct- of revetment construction must be evalu-
ly behind revetments (Knutson 1977). ated in light of the duration of the

construction period and the severity of Construction of a revetment is a
distu rba n ce. physical alteration of the shoreline
which brings with it many biological
Chronic effects. The presence of a re- changes. The structure itself buries
vetment in an area leads to a number of established flora and fauna. The revet-
physical and biological changes at the ment facing affords a new and different
site and in the surrounding shoreline. type of substrate. A revetment thus pro-
A revetment, when adequately designed vides a new habitat for various terres-
and constructed, will c6ntrol erosion of trial, benthic, and aquatic organisms.
the shoreline on which the structure The plant and animal communities which
sits; however, it will- not stabilize ad- colonize a revetment will have a commu-
jacent bea'ches or the foreshore in front nity structure which is different from
of the structure. the one in existence prior to construc-
tion.
Alterations in the foreshore follow-
ing revetment construction are site-spe- The diversity and abundance of or-
cific and difficult to predict. Unlike the ganisms living in and around a revetment
groins, revetments generally do not fa- will vary, depending upon the type of
cilitate beach accretion in either the revetment facing, energy conditions, its
backshore or foreshore regions and way location on the beach, and the type of
promote beach erosion in front of the substrate on which the revetment was
revetment (Brater 1950, Michigan Sea built. In some instances, a revetment
Grant Advisory Program undatei).Fore- can increase species diversity and abun-
shore erosion, however, will be less dance compared to what was previously in
from a revetment than if a bulkhead or the area. An example of such an area is
seawall had been constructed because Rincon Island, an offshore man-made is-
wave energy tends to be dissipated land in California which is protected by
rather than reflected as waves run up rock and tetrapod revetments. Rincon
revetment faces (Pallet and D ob bie Island's revetments support a diverse
1969). In fact, construction of revet- population of over 225 species of plants
ments on severely eroding shorelines and animals while the mainland, an area
can actually improve water quality by one-half mile distant with sandy beach-
reducing tu rb ulence ( C arstea et al. es, has fewer than 12 species (Brisby
1975a, U.S. Army Engineer District, 1977). Prior to construction, about 20
Buffalo undated a). Erosion of the fore- to 25 different species lived in the
shore can result from toe scour,increas- Rincon Island area (Keith and Skjei
ed backwash during severe storm s 1974). In general, revetment facings
(Brater 1950), and seasonal and long- that are highly irregular and have a
term fluctuations in the beach profile in shallow slope are favored biologically
front of the structure. Gifford (1977) over structures with smooth and/or
has noted bottom changes in front of steeply sloped surfaces. Such structures
revetments in Florida which usually in- tend to dissipate wave energy better and
volve deepening near the shore and have greater ability to support various
parallel offshore bar formation. organisms (Gantt 1975).

Well-designed and properly placed A change in beach substrate, as a
revetwents typically do not promote the result of revetment construction, may
beach growth as they offer very little alter the types of aquatic organisms
obstruction to littoral drift. Poorly de- which are able to utilize the area for
signed or placed revetments can cause growth, food, reproduction, and protec-
increased erosion of adjacent beaches tion. For example, fish species requir-
( Herbich and Ko 1968, Herbich and ing rocky substrates for spawning will
Schiller 1976). Erosion of acLiacent be favored in the riprapped areas over
beaches may result from alterations in those requiring sand, gravel, or vege-
water circulation patterns or from the tated substrates (U.S. Army Engineer
structure intruding into the littoral District, Buffalo undated a). Heiser
zone and obstructing littoral drift (Car- and Finn (1970), in a study of chum and
stea et al. 1975a, Gifford 1977). pink salmon in marinas and bulkheaded

areas in Puget Sound, found that the There are numerous alternative
spaces between rocks in riprap revetted structures and materials available for
areas provided protection for salmon fry building revetments. They are described
avoiding predators. earlier in this section and more com-
letely in the Shore Protection Manual
Revetments also affect the plant N.S. Army Corps.of Engineers 1973b) and
and animal communities in the upper the Survey of 'Coastal Revetment Types
foreshore and backshore zones. R evet- (McCartney 1976). in addition to the
ments constructed in wetland areas can alternative designs and---materials for
cause extensive damage to wildlife habi- revetments, eithbr offshore breakwaters,
tat. Carstea et al.(1975a) have describ- groins, or bulkhea-ds may constitute al-
ed wetland destruction as the "most ternatives depending on.the conditions
significant ecological impact of riprap at the site.
construction. " Revetments can damage
or destroy wetlands by covering up A revetment generally protects the
narrow fringe marshes and altering wa- landward area from erosion or scour due
ter circ ulatio n in larger s h orefro nt to waves or currents. An offshore break-
marsh areas. Wetlands are highly pro- water may accomplish this; same purpose
ductive areas which filter upland runoff by dissipating the wave energy before it
and function as the nutrient and sedi- strikes the eroding land area. A break-
ment traps. Destruction of shorefront water may secondarily interrupt the
wetlands eliminates waterfowl feeding, longshore littoral transport of sedi-
resting, nesting, and nursery habitats ments. This can buildup the beach which
and destroys the habitat for other further protects the adjacent uplands.
birds, reptiles, and s mall mammals Objections to a breakwater as an alter-
(Boberschmidt et al. 1976, Carstea et native to a revetment are the cost, the
al. 1976, Herbich and Schiller 1976). interruption of longshore transport and
possible impact on adjoining land areas,
Cumulative effects.No studies were and the visual impact. In addition, a
found that investigated cumulative phys- breakwater might constitute a hazard to
ical and biological impacts due to the navigation.
existence of a number of revetments
within a coastal area. Revetments are A groin or system of groins might
relatively small in size. The effects of indirectly accomplish the same function
a single revetment may be relatively in- as a revetment by causing the accurrula-
significant in a coastal area due to the tion of littoral drift which widens the
,size of the structure, the size of adja- beach cross section and ultimately pro-
cent undisturbed areas, and even re- tects uplands from wave attack. The
cruitment into the revetment- produced groins, might reduce wave attack depend-
h a bitat. The physical and biological ing on spacing, height of the groi,ns
impacts from the construction of a num- and angle of wave attack. The groins
ber of revetments in a coastal area may can cause undesirable side effects due
have a synergistic effect. For example, to their tendency to interrupt longshore
extensive riprap revetting of a sandy transport with the resultant impact on
coastline will change what once was a downdrift beaches. Erosion problems are,
sandy habitat into a rocky intertidal in some instances, only displaced by
habitat. Examination of the physical groins.
and biological impacts of revetment con-
struction on a case-by-case basis ig- A bulkhead or seawall could be used
nores a host of potential cumulative as an alternative to a revetment. How-
physical, chemical,and biological impacts ever, due to the greater expense and
(Fetterolf 1976). No information was lack of environmental advantages, bulk-
found regarding the cumulative effects heads would normally not be selected as
of revetments in connection with other alternatives to revetments. The circum-
shoreline structures. All structures in stances under which bulkheads are used
an area should be evaluated concomi- are described in another section of this
tantly. report.

Structural and Nonstructural Alterna- There are a number of nonstructural
tives procedures which may constitute viable
72

alternatives to the revetments depend- land to allow relocation of the endan-
ing on the site specific circumstances. gered building and a structure which can
be economically moved. This remedial
Beach nourishment from onshore or action miqht have to be repeated in the
offshore locations can be used to widen future.
and raise the beach profile. T his, in
turn, will dissipate the wave energy Regional Considerations
and may reduce erosion of the upland
areas. This solution is temporary as Riprap revetments are a common
the wave energy causing erosion will be means of protecting eroding shorelines
focused on the new beach and, in time, in Puget Sound (Coastal Region 1). They
transport the sand either offshore or are also common in estuaries and harbors
alongshore, thus re-exposing the erod- along the coast of Washington, Oregon,
ing area. Beach nourishment can also and northern California. Riprap revet-
be used in conjunction with groins as ments are used to protect railroad
an alternative to revetments. tracks, roadbeds, residential lots, and
uplands from erosion. Heiser and Finn
Vegetation can also be used to re- (1970) studied chum and pink salmon in
tard erosion. Vegetation is particularly marinas and bulkheaded areas in Puget
suitable against wind- or rain-caused Sound. These authors recommended using
erosion. V egetatio n cannot withstand riprap revetments with irregular, 40' or
constant action of waves or currents less angle facings in lieu of vertical
and would need to be supplemented by bulkheads as this type of revetment pro-
other structures, or means, to prevent vides protective habitat for young sal-
erosion. Vegetation is often used well mon.
above the surf zone for stabilization
and accretion of sand on dune areas. No information sources concerning
In areas of relatively low wave energy, revetments unique to Coastal Regions 2,
the establishment of a fringe marsh 6, 7, or 8 were found. Physical and bio-
might be an alternative to revetment logical impacts are similar to those
construction. previously described.

Most structures exposed to sea Limited quantitites of hard igneous
conditions are ultimately subject to ero- rock in peninsular Florida (Coastal Re-
sion and failure. Th-is problem can be gions 3, 4, and 5) make riprap revet-
avoided by zoning against development ments expensive as rock must often be
of foredunes, cliffs, or other areas sub- shipped in from other states. Coquina
ject to erosion by the sea. Setback reg- rock, mined from quarries in the St.
ulations are another means of assuring Augustine area,has proven to be a dur-
that structures will not be threatened able construction material for marine
by shoreline erosion at a future date. structures; however, this source of sup-
One problem is that it is not always ply is almost exhausted. Limited sup-
possible to forecast the extent of possi- plies of hard native limestone are
ble erosion over the life of the struc- available in the Tampa area (Collier
ture. This is particularly true in cases 1975).
where groins, jetties, and breakwaters
are being constructed in adjacent areas RAMPS
which might lead to rapid accretion or
erosion of the shoreline. Also, unusual Definition
storm and wave conditions can have
drastic effects on a shoreline that has A ramp is a uniformly sloping plat-
been reasonably stable in the previous form, walkway, or driveway. The ramp
years. Assuming an upland building or commonly seen in the coastal environment
facility is threatened by an eroding is a sloping platform for launching
shoreline, an alternative to revetting small craft. A launching ramp will nor-
the shoreline is to move the building or mally slope continuously from above the
facility back on the lot, leaving the high water line to below the low water
forward part of the land to erode. line to allow launching of boats or air-
This, of cou rse, req uires sufficient planes under varying tidal or water
73

level conditions. A launching ramp may Dunham and Finn(1974) recommend
be surrounded by additional structures, that the ramp be paved to about 5 ft
such as pilings or piers, and may be (1.5 m) below extreme low water level.
protected by a breakwater. There should be a level shelf of loose
aravel at the end of the ramp to prevent
Structure Functions a vehicle from sliding into the water if
there is a loss of traction or brakes.
A*Iaunching ramp provides a means
to set afloat and retrieve boats which The most common construction tech-
are usually mounted on ru b ber-tired nique uses a gravel foundation covered
trailers. However, airplanes also use by a layer of concrete. The thickness of
ramps. Launching ramps will usually these layers ranges from 3 to 6 in (8 to
be accompanied by parking lots for 15 cm). Deep, square-shouldered grooves,
automobiles and trailers and will be con- perpendicular to the slope, should be
structed in conjunction with a landing pressed into the concrete during con-
pier or other shoreline structures, such struction (Dunham and Finn 1974). This
as pilings or breakwaters. not only provides greater traction, but
the ramp will last longer than one with
A ramp has many of the same phy- a course finish without deep grooves.
sical characteristics as a revetment;
however, its function is different. Re- Submerged ramps, constructed of
vetments are usually installed in high precast slabs, have provided the most
energy environments, whereas ra m p s satisfactory results. One construction
are installed in relatively q uiescent method uses precast 6- by 12-in slabs
areas. placed 3 in (7.5 cm) apart. The gaps are
filled with coarse gravel (Dunham and
Site Characteristics and Environmental Finn 1974). Other methods have not prov-
Conditions en as successful. Large concrete bricks
and building blocks often dislodge if
Ramps extend into the water, per- the suborade is soft. Asphalt paving
pendicular to the shorelines and slope will not hold up well if used on the
at an angle of 12% to 15% from the ter- submerged part of the ramp, while unpav-
restrial zone to below the low intertidal ed ramps will deteriorate (Dunham and
zone. They are usually constructed in Finn 1974).
areas where there is fairly deep water
close to shore and where there is a rea- Sufficient pier space should be
sonable amount of protection from winds provided for boardinq and for holding
and waves. Ramps are often associated the boat while launching. Piers are
with marinas and would, therefore, be usually located on both sides of the
placed in similar environmental condi- ramp. Dunham and Finn (1974) recommend
tions. that a sincle-lane ramp be at least 15
ft (4.6 M) wide. They suggest that on a
Placement Constraints multiple-lane ramp,raised divider strips
or marked lanes are not necessary and
Engineerinq. The design of a may reduce optimum usage during peak
launching ramp may vary depending on hours.
expected usage and site characteristics.
Figures 37 and 38 show examples of two Proper drainage should be provided
different ramp designs. Ramps range for washdown facilities which are often
in width from 10 ft to over 50 ft (3 to used in saltwater areas. Oil, arease,
15 m ). Length may vary to over 60 ft and other pollutants may be washed off
(18 m). The slope of a ramp should be when cleaning the boat and trailer. For
between 12% and 15%. If the ramp slope this reason, drains should be connected
is flatter than 12%, trailer wheel hubs to a sewer system rather than returned
have to be submerged while launching. into the water.
Slopes steeper than 15% can be danger-
ous unless the driver is very skilled Ramps should be placed in reason-
(Dunham and Finn 1974). ably quiet waters to minimize the number

j6k .4L.A.- 14

14 SKI

vs
1jrPAw;"A
dW It

7@t

Figure 37. An elaborate launching ramp in Coos Bay, Oregon. Floating piers held in
place by piles accompany the ramp. Photograph courtesy of CH2M Hill, Inc.

-71

-AW

Figure 38. A simple launching ramp in the vicinity of Panama City, Florida. Photo-
graph by E. L. Mulvihill.

of protective structures required. They grating, asphalt, or any other material
should be placed in well-flushed areas with a reasonable degree of structural
to avoid the buildup of exhaust, petro- integrity and resistance to decay in an
chemicals, and other pollutants. To fa- aquatic environment.
cilitate launching, it is desirable that
currents be minimal. Ramps have many Expected Life S_p.@n -
of the same placement constraints as so-
lid-faced revetments. The section of The literature did not provide the
this report on revetments should be re- specific information on the expected
viewed before evaluating the environ- life span of ramps. Unpaved or submerged
mental compatibility of a ramp. Struc- asphalt ramps generally will not last as
tures located around the ramp, such as long as concrete ramps.
jetties, breakwaters and piers, should
be designed to prevent adverse envi- Summary of Physical and Biological
ronmental impacts. LM2@ _Ct S

Socioeconomic. Community use of Construction effects. The construc-
a ramp is encouraged over individual tion of a ramp can cause suspension of
ow ners hip. This will help to limit the sediments causing increased turbidity,
number of ramps. One ramp usually reduction in productivity, smothering of
causes minimal adverse impacts. As the benthic organisms, release of toxic sub-
number of ramps in an area increases, stances, and altered bottom habitat. A
the impacts become more intense. specified area of shoreline habitat is
removed from the aquatic system and is
Poured concrete is probably the replaced, in most cases, by less produc-
easiest, least costly, and most popular tive habitat,particularly if the launch-
method of ramp construction. For the ing ramp area is used heavily.
submerged rarrp section, precast slab is
less costly than poured concrete and The use of construction equipment
provides better results (Dunham and will increase noise and air pollution.
Finn 1974). However, these impacts are usually-
slicht and short in duration. Construc-
Secondary socioimpacts should be tion equipment can also disturb a wet-
considered when evaluating the environ- land edge zone by causing soil compac-
mental compatibility of a ramp. T hese tion, which can have lasting adverse
include all the impacts associated with effects.
increased human usage, such as conges-
tion, littering, and discharging pollu- Chronic effects. The greatest im-
tants. pacts are usually caused by related
activities, such as dredginq, protective
_Pj21o,qical. Disturbance of wetlands structures, channel deepening, parking
should be minimized. During construc- facilities, and increased human usage in
tion, matting or vehicles designed to the area. Boats and planes cause in-
prevent soil compaction should be used. creased turbulence as well as petrochem-
Extra filling of the wetlands should be ical and noise pollution which can af-
avoided. Turbidity control devices fect the diversity of fish and wildlife
should be used when necessary to pre- inhabitina the area. Ramps can make for-
vent adverse impacts on the local aqua- merly inaccessible areas accessible to
tic community. Ramps should be con- fishermen and sightseers. This increased
structed in areas where minimal or no accessibility may result in modifica-
dredging is required. Review of the tions to existing populations of organ-
section on revetments in this report isms. It is also possible that the
would help to determine the biological greater freq'uency of boat wakes may
placement constraints for ramps. initiate or increase shoreline erosion
along the waterway, causing a need for
Construction Materials other protective structures.

Construction materials may consist Cumulative effects. Construction
of gravel, shell, wood, concrete, steel of a ramp will replace some interfidal

area. The associated parking facilities changes,"and also recommended that ramps
should be placed on the uplands. The be located in between "drift sectors" or
impact of one ramp may be minimal. If "independently operating erosion-trans-
the area becomes an attractive launch- port-accretion beach systems."
ing area, then it may attract commercial
facilities.The habitat alterations increase In the New Orleans District of the
accordingly. U.S. Army Corps of Engineers in the
Coastal Region 3, the most common type
Structural and Nonstructural of ramp consists of compacted gravel or
Alternatives shell covered by concrete (Carstea et
al. 1976). These authors gave the di-
The purpose of most ramps is the mensions of a typical boat ramp as 10 to
launching and retrieval of small craft. 12 ft (3 to 4 m) wide and 40 ft (12 m)
This same function can also be perform- long. A typical seaplane ramp is 25 to
ed by a hoist which can pick the boat 30 ft (8 to 9. m) wide and 55 to 60 ft
off a trailer and swing it into the wa- (17 to 18 m.) long. Concrete and timber
ter. Such a device usually requires a seaplane ramps are similar to the boat
pier or other structure to allow access ramps.
to water of sufficient depth. A sling
would be more applicable in areas where Shore profiles encountered in the
there is relatively deep water close to various coastal reoions will determine
shore. the design and feasibility of ramps and
the desirability of utilizing alternate
A marine way (dolly) is another structures, such as slings and dollies.
viable alternative which avoids the nec-
essity of constructing a pier and/ or PIERS, PILINGS AND OTHER SUPPORT
dredging to reach water of sufficient STRUCTURES
dept@ (Figure 39). This launching tech-
nique involves lifting the boat with a Definitions
sling onto a platform mounted on rails
(the dolly). Launching is achieved by A pier is a structure, usually of
running the boat down the railed struc- open construction, extendinc into the
ture and into water of sufficient depth. water from the shore. It serves as a
This technique has the advantage of al- landing and mooring place for vessels or
lowing launching in areas with shallow for recreational or commercial uses.
slopes or at low tides. It is generally This definition of a pier includes tres-
not feasible to cross extensive tidal tles, platforms, and docks extending
flats with a ramp. into the water for similar, purposes. The
definition does not include bridge
Regional Considerations piers. Floating structures anchored with
pilings are sometimes called floating
Most of the literature contained in- piers. Sometimes jetties, groins, and
formation applicable to all of the coastal other structures built 'primarily for
regions. There was some information coastal protection purposes are incor-
specific to the north Pacific and Gulf rectly called piers.
coast (Coastal Regions 1 and 3). In
the Puget Sound area of Coastal Region A pile is a long heavy timber,
1, siting ramps on "accretional or roll- steel, or reinforced concrete post that
back dry beaches" should be avoided has been driven, Jacked or jetted, or
due to possible changes in beach profile cast vertically into the ground to sup-
(Bauer 1973). Less than 4% of the port a load. A pile structure will nor-
shoreline in this area consists of dry mally be an open structure where water
beaches. If ramps are placed in this can circulate between the individual
area, the protective structures should piles or pile clusters. Sheet piles are
be constructed so they do not interfere. steel or concrete sheets or slabs which
with "beach drift action." Bauer (1973) are driven edoe to edge in a straight
suggests considering "flexible-contour row to form a bulkhead or wall. They
bolt and hinge segmented ramp pads can also be driven in circles, squares,
that can be adapted to beach profile or in other closed shapes to form bridqe

Figure 39. Marine way at Point No Point beach resort in Puget Sound, Washington.
Photograph was taken at low tide. Photograph by C. A. Francisco.

piers, cofferdams, or caissons. U nlike Placement Constraints
individual piles, use of sheet piles nor-
mally will not result in an open struc- Engineering. A typical residential
ture. fixed pier is 40 to 60 ft (12 to 18 m)
in length. For a marina complex it is
Structure Functions common for a pier to extend 200 to 250
ft or 61 to 76 m (Carstea et a]. 1975).
A pier usually functions as a land- Piers may be straight or have "L" or "T"
ing and mooring place for vessels. Such configurations (Figure 42).
a pier might also be used for loading or
discharging cargo. Another function is Piles are driven to a depth which
to provide access to deep water from will provide stability. This depends on
land. This is usually in conjunction the bottom characteristics of the site,
with a landing or mooring place. A pier as well as the lateral forces working
can also be used for boat launching and against the structure. For example, a
retrieval by means of a hoisting mech- pier used for mooring purposes would be
anism located on the pier. A pier way subjected to the forces of a vessel
also provide recreational usage, as for striking the side and would, therefore,
fishing or sight-seeing. Used for these have to support a greater lateral load
purposes, a pier might also serve as a than a pier used solely for fishing.
platform for restaurants or other com- The length of pile extending above the
mercial ventures. wat-er is dependent on wave height and
tide. According to Carstea et al. (1976)
Separately or in clusters, pilings enough pile should be exposed to allow
can perform several functions including: the decking to remain at 'least 3 ft (0.9
m) above the water and provide 3 to 4 ft
0 Mooring vessels, anchoring floating (0.9 to 1.2 m) for moorino or handrails.
rafts or floating platforms (Figure
40); Pile dimensions vary greatly. A
mooring pile is usually around 10 in (25
0 Supporting aids to navigation,such cm) in diameter with 8 to 10 ft (2.4 to
as lights, ranges, day markers, 3.0 m) exposed above Mean high water
channel markers, or reflectors (Carstea et al. 1975a). A dolphin is
(Figure 41); usually constructed with a center pile
approximately 12 to 14 in (30.5 to 35.6
0 Serving as the fenders or protec- cm) in diameter, surrounded with piles
tive features for piers, landings, from 8 to 10 in (20.3 to 25.4 cm) in
b rid ges, or other structures. diameter. A heavy wire rope is generally
used to bind them together (Carstea et
Pilings are also the basic element al. 1975a).
in many larger structures used for the
mooring vessels and providing coastal Wood pilings should be treated to
p rotectio n. prevent decay and destruction due to
marine borers (Figure 43). Treatment
Site Characteristics and Environmental may include toxic surface coatings, pile
Conditions sheathing, or creosote-coal tar impreg-
nation. In areas where gribbleLimnoria,
Piers extend into the water from a and marine clam,Pholas, attack are com-
bulkhead or from the natural shoreline. mon, the American Wood-Preservers' Asso-
They may extend in different directions ciation (AWPA) C3 Standard recommends a
to various depths, depending on naviga- dual treatment for wood pilings (Henry
tional requirements or their designated and Webb 1974). The addition of an
function. The location of a single pile insecticide may retard infestation
or piling is also dependent on function. (Lindgren 1974). Methods of protection
are updated by the AWPA and should be
Piers, pilings, and pile-supported consulted periodically.
structures freq ue ntly occur with the
marinas which are often located in estu- An open-pile structure is recom-
aries and bays. mended over a solid-fill structure. The

Aii
AAL,

00
A-,

-41

-WAS
7-A

-'414

Figure 40. Floating pier at Kingston Marina, Kingston, Washington. Note rubble
mound breakwater in background. Photograph by C. A. Francisco

2X:

V
4

Figure 41. Piling in Key West, Florida supports navigational aids. A
concrete capped pile pier is also noticeable in the picture. Photograph
by E. L. Mulvihill.

mom
h qI"
00
4"

k
J, ""'Mmm
-ski 11

Figure 42. Open-pile pier near Hansville, Washington. Note the floating pier at the
end. Photograph by C. A. Francisco.

_A(

A It
lk,

Figure 43. Gribble damage to a mooring dolphin in Key West,
Florida can be seen near the water level. Photograph by
E. L. Mulvihill.

advantages include fewer adverse envi- Socioeconomic. The number and size
ronmental impacts and ease of removal if of P supported structures and piers
so desired. Open-pile structures are should be minimized in a given area.
also advantageous where substrate con- The use of over-water locations for non-
ditions are unstable. Adequate spacing water-dependent structures should be
of piles is important to prevent inter- discouraged (Carstea et al. 1975a). To
ference with water and sediment move- limit the number of piers,it is suggest-
ment (Bauer 1973). ed that single piers be used coopera-
tively by the community. This is par-
Site characteristics should influ- ticularly stressed for subdivisions,
ence the design of a pier. According motels, and multiple dwellings (South
to the Coastal Plains Center for Marine Carolina Marine Resources Division
Development Service (1973), floati n g 1974). Structure size should be re-
piers can affect beach sand movement. stricted to that which is necessary for
They recommend open pile piers in the designated purposes. Piers should not
areas of significant littoral transport hinder public use of the water,
and longshore currents. Floating piers navigation, or adjacent shoreline. Ex-
are suggested for areas where visual tension of the structure beyond the mean
impacts should be minimized and where high water line should be avoided (Car-
boat traffic would not be hindered by stea et al. 1976). The socioeconomic
their presence. impacts of public, private, or joint use
of a pier should be considered.
Another factor to consider is tidal
range. Where the tidal range is above Biological. During construction,
4 ft (1.2 m), floating piers are recom- turbidity shoula be kept to a minimum
mended because they provide easier ac- and turbidity control devices should be
cess to boats throughout the tidal cycle used when necessary. Alterations of
(Ayers and Stokes 1976). Floats can be shoreline and littoral habitat should be
removed in the winter to avoid ice dam- avoided (Florida Game and Freshwater
age (Carstea et al. 1975a). Fish Commission 1975). The placement of
the structure relative to the sun, as
During the life span of pilings or well as the height and width of the
a pile-s u p ported structure, several deck, are important factors to consider.
changes usually occur which should be The structure should be placed high
considered in the desion.These changes enough above the water or marsh surface
alter the impact of forces acting on the to prevent shading. A narrow pier ex-
structure. As marine growth increases tending from north to south would not
on the pile, the diameter, roughness, produce as much shade as a wide pier
and concomitant drag coefficient will in- running from east to west(Gifford 1977).
crease. Scouring at the base of the pile The damage to wetlands can be minimized
will decrease pile support. Also, as by constructing an elevated boardwalk to
piles are attacked by wood borers or as provide access to the dock or pier (En-
they corrode, structural damage will de- vironmental Quality Laboratory Inc.
crease pile strength. (See U.S. Army 1977). The size, number, and placement
Corps of Engineers 1973b for further of piling should be evaluated relative
information and calculations). to the various biological zones over
which the pier will extend.
The type of wave force occurring
in the area should also be considered in Construction Materials
the design. For example, breaking
waves create a greater force on the pile Piers, pilings, and structure sup-
than do nonbreaking waves. (U.S. ports are,generally constructed of wood,
Army Corps of Engineers 1973b should concrete, or steel. Decking, stringers,
be consulted for further information and bents, and caps are made from wood,
calc ulatio ns. The size, number, and steel, or concrete members of various
placement of piling should be correlated sizes (Figure 44). Construction materi-
to the various energy zones in which als that do not release toxic substances
the pier is located. are preferred.

DECKING

,,@STRINGER
+-r(- A P

*-r-PILE

DESIGN WATER LEVEL

EXISTING BOTTOM

Figure 44. Cross-sectional view of a typical pier. Dimensions and details to be determined by particular
site conditions.

Water quality should be considered Conflicts may arise concerning adjacent
when choosing construction materials. land uses and area aesthetics. In areas
Areas with poor water quality will gen- where longshore currents, tides,and lit-
erally not support populations of grib- toral transport are influential, float-
bles or borers. If materials that are ing piers can alter beach sand movement
not resistant to their attack are utilized patterns (Coastal Plains Center for
and water quality is significantly im- Marine Development Service 1973).
proved, there may be problems with
premature structural failure. Shading from pile-supported struc-
tures may modify the water temperature
Expected Life Span and wetland habitat. Depending on the
amount of shading, there may be a reduc-
Pilings of wood, steel, or concrete tion or absence of algae and grasses
will generally have a life expectancy of under piers (Gifford 1977). But it
30 yr or more if they are treated. The should also be noted that piling and
environmental factors of an area greatly piers offer substrate for alcae growth
affect deterioration rates. Conditions in some areas where algae di@ not for-
of high salinity and high temperature, merly grow because the bottom was below
along with the boring organisms, will the photic zone or presented unstable
likely increase the deterioration process sediment conditions. White (1975) indi-
to some degree. cated that single residential piers in
fresh water are not likely to cause a
Plans for removing the piling and significant reduction in phytoplankton
other support structures after their ef- production.
fective life span should be submitted
when structure is proposed for con- Increased use of the area causes
struction. There are severe navigational related impacts. Boat exhaust and do-
problems in many areas of the United mestic emissions can decrease water
States,such as in New York Harbor due quality (Carstea et al. 1975b). Impacts
to the chronic decay and drifting away may also be caused by increased fishing
of pieces of old support structures. and litter disposal (Gifford 1977).
Piles or portions of piles remaining just
below the water level also present navi- Unless treated, the pilings and
gational hazards. other structures provide suitable sub-
strate for algae and new attachment sur-
Summary of Physical and Biological faces for invertebrates. These struc-
Impacts tures also provide cover and feeding
sites for fishes and may be used by var-
Construction effects. Construction ious birds for nesting or perching
causes increased turbidity and sedimen- (Carstea et al. 1976). Sessile organisms
tation which, depending on severity, on the exposed surfaces of a piling or
may reduce primary productivity, inter- other structure as well as the presence
fere with respiration of fish, alter the of the structure can attract motile or-
s uita bility of spawning areas, reduce ganisms, such as fishes, which feed upon
b otto m habitat diversity, and smother the organisms or use the structure for
benthic organisms(Carstea et al.1975b). shelter. Such areas generally offer very
Resuspended bottom sediments may re- good fishing. Piles offer resting places
lease toxic substances. Noise and vibra- and feeding observation posts for coast-
tion, along with turbidity, may tempo- al or marine birds, such as pelicans,
rarily drive fish or invertebrates from kingfishers, herons, egrets, and cormo-
the area or cause behavioral modifica- rants (Carstea et al. 1976). The use of
tions. However, in some instances fish- piles and piers by gulls seems to be a
es have been attracted to construction universal phenomenon. Channel markers
sites due to the suspension of benthic are frequently used as nesting platforms
organisms. by osprey.

Chronic effects. Docks and piers Cumulative effects. As the number
can cause navigational problems and in- of pile s pported structures increase in
terfere with public use of the water. a given area, the impacts on that area

will increase. The magnitude of adverse 0 Use the launching ramps or other
impacts may be dependent on the char- launching structures. Provide up-
acteristics of the site and on the type land storage of vessels. This,
of structures in the area. Open pile of course, is limited to smaller
structures do not impede water or sedi- size vessels which can be conven-
ment movement unless the pilings are iently removed and transported on
spaced very closely. Sediment deposits dry land.
will build up if too many pilings are lo-
cated in a poorly flushed area or in one 0 Forr community marinas to elimi-
of slow water flow. The shoreline will nate single piers at each water-
stop littoral drift, filling with sediment front lot.
(Carstea et al. 1976). Aside from the aesthetic consider-
The impact from shading increases ations, loss of navigable water area,
as the area being shaded increases in and-i-n rare instances-interference with
size. Water temperature modifications sand movements, the impacts of open pier
and reduced primary productivity may structures are minimal. Solid pier
have an adverse impact on the food structures are generally less desirable
chain. The absence of algae and grass- and more costly. Elimination of piers
es eliminates hiding areas for fish and by multiple use of existing piers or
other organisms, but this may be offset launching facilities appears to be the
by the new habitat created on the sub- best alternative.
merged structures (Figure 45). Reqional Considerations
Structural and Nonstructural
T_11@_rnatives Very little information was found
regarding regional specific aspects of
The commonly noted function of a piers, pilings, and other support struc-
pier is to serve as a landing place for tures. The types of materials utilized
vessels. Piers, due to their open struc- will vary according to availability
ture, disrupt water circulation and bot- within each region. The length of piers
tom dwelling species much less than al- may vary depending on the distance to
ternative solid structures, such as walls deep water which is generally quite dif-
or sheet pile caissons. ferent on the Gulf coast (Coastal Region
3) and in the Chesapeake Bay (Coastal
The most common alternatives for Region 6) as compared to areas in Puget
piers are: Sound (Coastal Region 1) and in New Eng-
land (Coastal Region 7). The length of
0 For mooring vessels, an anchor or piles may also vary depending on the na-
mooring buoy could be used. This ture of sediments encountered in a re-
is more common in New England gion. In areas where bedrock is close to
and areas of extreme tidal range. the water body floor, piles would be
shorter. The length of friction-type
0 For mooring vessels and providing piles will also be affected by sediment
access to the shore, a floating pier characteristics.
could be used. This alternative
might be aesthetically more desir- Infestation of piles by marine bor-
able but will probably cause in- ers tends to vary geographically. Grib-
creased shading and affect littoral bles (@@imnori@a) breed only in tempera-
transport. tures above 570F (14"C) and are preva-
lent in southern California (Coastal Re-
If the objective is to eliminate the gion 2) and from the Gulf coast to the
pier, there are two nonstructural alter- middle Atlantic (Coastal Regions 3, 4,
natives available: 5, and 6) (Lindgren 1974). The abundance
and growth rate of shipworms (Teredo)
0 Combine the purpose of the pro- also varies geographically. Within a
posed pier with that of piers in region, factors other than temperature
the vicinity to reduce the overall affect marine borer populations. Heavily
number of piers. polluted areas may not be habitable by

,im

Figure 45. Submerged structures offer substrate for the
attachment of various types of marine organisms. Photograph
by C. A. Francisco.

borers. In such areas, pilings will not fishing supplies. Larger platforms used
have to be replaced as frequently as in for construction or drilling would nor-
nonpolluted areas. Fluctuating quanti- mally be considered as ships, barges, or
ties of fresh water in an estuary can hulls.
also affect populations. If the salinity
decreases sufficiently, borer populations Site Characteristics and Environmental
will decrease. Physical factors may also Conditions
have an effect on population density.
A pile subject to high wave action will Buoys are utilized in all types of
not support the population of gribbles energy environments, wh i 1 e floatinq
that a pile in quiet waters will support platforms are usually used in relatively
(Hochman 1967). Constant high salinity sheltered areas.
and tropical temperatures accelerate the
decomposition of chemicals used in creo- Placements Constraints
sote treatment (Lindgren 1974); there-
fore, piling in such areas are more sus- Engineering. The sizes and shapes
ceptible to attack. of buoys and floating platforms depend
on the function. For example, buoys or
B U 0 Y S A N D FLOATING PLATFORMS floats used in swimming areas or for
mooring recreational craft would be
D efi nitio n s smaller and of lighter construction than
a buoy or float used in open water.
A buoy is an anchored or moored
floating object intended as an aid to The site and method of placement
navigation, for attachment of vessels or should be considered carefully. It is
instrumentation, or to mark the position important that buoys and platforms be
of something underwater. If the buoy properly anchored according to their
is to be used primarily for mooring ves- size and weight. Areas where bottom
sels, it is called a mooring or anchor sediments frequently shift should be
buoy. avoided. Water level fluctuations
should be considered when designing an
A platform is a horizontal flat sur- anchor system. Platforms, buoys, and
face usually higher than the adjoining attached vessels should not interfere
area. A floating platform is a structure with navigation.
that floats on water and is held in place
by anchors or piles or other mooring Socioeconomic. Platforms and buoys
devices. A series of platforms in a line should not interfere with public use of
extending from the shoreline to deeper the waterway. It is advisable to design
water would be considered a floating them so that they are clearly visible to
pier. boaters. The presence of buoys and
floats is generally accompanied by in-
Structure Functions creased human usage of an area. The
secondary impacts of the human usage
Buoys are most commonly used as should be considered.
navigational aids to mark channels,
shoals, harbor entrances, etc. Some- Biological. If drums or barrels
times buoys have lights, reflectors, or are utilized as floats,those once con-
horns mounted on them. Buoys are also taining toxic substances are not suit-
used as markers for sunken objects and able. It is advisable to coat foam
for suspending analytical instrumenta- floats to prevent chips and flakes from
tion, such as current, wave, or water littering the water. To avoid contami-
quality monitoring equipment. nation, all coatings must be dry before
placing floats in the water. The sub-
Floating platforms are flat struc- merged surfaces of buoys and floats and
tures which are generally larger buoys the anchor system offer habitat for var-
or floats.They are used for recreational ious types of attached organisms. They
purposes,such as swimming and diving, also supply refuge for various types of
or commercial purposes such as selling fishes.

Construction Materials of the installation of buoys and float-
ing platforms is minimal.
The flotation material for floating
platforms and buoys generally consists Chronic effects. Shaded areas caus-
of polystyrene, ployurethane or hollow ed by floating structures and the areas
steel, aluminum, fiberglass, or concrete occupied by their anchors are usually
structures. The most popular type of small and generally would not be expect-
floats are polystyrene and polyurethane ed to result in measurable effects.
foam. They should be coated with a pre- Shading from platform decking may result
servative to prevent deterioration and in a small decrease in primary produc-
attachment of marine flora and fauna. tivity. The impact is dependent on the
The coating may consist of polyvinyl- size of the structure. Buoys and plat-
acetate emulsion or dense polyurethane forms provide habitat for sessile organ-
(for polystyrene), fiberglass and resin isms and cover for fish. Pelagic game
for polyurethane), plaster, or concrete fish are attracted to buoys and floats.
Nunham and Finn 1974). When using They are, therefore, popular sport fish-
polyurethane, the monocellular type ing spots.
should be used, as it is the only type
that is nonabsorbent. Extruded polysty- Cumulative effects. Cumulative
rene (Styrofoam) is totally impermeable effects were not considered in the lit-
by water and may be preferred over erature. It is apparent, however, that
expanded-pellet polystyrene (bead- there can be aesthetic and navigational
board), which is more susceptible to problems created if the number of float-
water penetration (Dunham and Finn ing objects is allowed to proliferate.
1974). Polyurethane is naturally hydro-
carbon-resistant. Polystyrene can be Structural and Non-Structural
made hydrocarbon resistant. T his is an Alternatives
important factor to consider when locat-
ing structures in an area susceptible to One alternative to buoys used for
petroleum products. In the past, hollow navigation aids or markers would be pile
floats or fiberglass or metal were used. structures. flooring buoys could be re-
Hollow-shell floats are more susceptible placed by fixed structures such as dol-
to leakage and are being replaced by phins or piers. The necessity for buoys
shells filled with foam. Wood flotation could be eliminated by installing a
devices are used in some areas of the launching ramp and requiring land stor-
country, such, as the Pacific Northwest. age of the boats.
Platform decks may be constructed from
wood, concrete and plastic materials. Regional Considerations
Anchor systems may be made from rope,
cable, or chain. Anchors can be patent- Most of the information in the lit-
ed anchors of steel or can be made of erature is applicable to all of the
concrete blocks and various makeshift coastal regions of the United States.
things, such as junk auto parts. The Buffalo District of the U.S. Army
Corps of Engineers (undated a) (Coastal
Expected Life Span Region 8) proposed that general permits
be issued for navigation, mooring, and
The life span of buoys and floating special purpose buoys and floating plat-
platforms was not addressed in the lit- forms in New York State. Specific re-
eratu re. Materials treated against ma- strictions for that area included limit-
rine growth and corrosion will last long- ing a Veck sTace area to not more than
er than untreated materials. The sever- 200 ft (61 m ) and restricting platform
ity of environmental conditions where extension to no more than 100 ft (30.5
they are utilized will greatly affect m) waterward from the high water line.
their longevity. HARBORS FOR SMALL CRAFT
Summary of Physical and Biological
Impacts Definition

Construction effects. The effect A harbor is a protected water area

offering a place of safety to vessels. 0 A system of piling, floats, piers,
Natural harbors are those where the anchor buoys, or other devices for
protection is provided by the natural mooring small craft.
geography of the area. Artificial har-
bors are those where natural protection A small craft harbor might also in-
does not exist (i.e., on an open coast clude the following items:
lin e) or where substantial structures
are required to provide adequately pro- 0 Special facilities, such as piers
tected water areas. Small craft harbors for fueling and taking on provi-
are protected areas whose depth and sions;
maneuvering area limit usage to small
craft. Harbors specifically designed or 0 A ramp or launching device for
constructed for fishing boats are includ- placing small craft in the water
ed in the general definition of small and removing them;
craft harbors. Marina is used synony-
mously with small craft harbor,but oen- 0 Backup land for parking vehicles
e rally refer to harbors for pleasure and providing access to the harbor
craft. facilities.

Although the word port is some- There is no exact definition as to
times used interchangeably with harbor, how many of the above features are im-
it is clearer to use port to signify a plied by "small craft harbor." But, many
place, usually both a harbor and town, of the structures considered in this re-
suitable for landing people or goods. port are common components of small
craft harbors (Figures 46, 47, and 48).
Technically, a harbor for small
craft could be the water surface in a Small Craft Harbor Functions
naturally or artifically protected area in
a bay, lake, or estuary. However, as The function of a small craft har-
commonly used in the United States, a bor is to provide shelter for small
small craft harbor also includes the nec- boats and, in some cases, to supply sup--
essary features for the safe navigation port facilities for the activities car-
and mooring of small craft. This would ried out by the boats.
include the following features:
Site Characteristics and Environmental
0 A natural or man-made entrance Conditions
channel of sufficient width and
depth for traffic use; Small craft harbors usually occupy
several tidal zones extending from the
0 A natural or man-made basin of terrestrial zone through the subtidal
sufficient depth and size for an- zone when the accompanying parking fa-
choring or mooring craft; cilities, launching ramps, and breakwa-
ters or jetties are included.
0 A break water su rrou n din g the
basin to provide protection from Small craft harbors are more com-
natural waves and swells from monly located in bays, estuaries, inlets
passing vessels. It can also pro- or coves, rather than on open coasts.
vide p rote ctio n from s w ift cur- Due to recent concern over construction
rents. The breakwater might con- in the intertidal and near intertidal
currently function as a jetty to zones and the diminishing number of
assist in maintaining depth in the feasible sites,marinas are now frequent-
entrance channel or as a groin to ly dug out of upland areas (Carlisle
prevent sediment or sand from en- 1977).
tering the basin. The breakwater
might in ci d e ntally serve as an Placement Constraints
access road or path to the harbor
or to the waterway in which the En 'ineering. Environmental condi-
harbor is located; tions of the specific site should be

%
&

ons

Figure 46. Crescent City, California inner boat basin. Photograph courtesy
Wooster Engineering Corporation.

-Ox!t,

.............

4t:-

SAM.

Fi gure 47. Winchester Bay, Oregon. Photograph courtesy of CH2M Hill, Inc.

4Vr
A

WIN-

*77. "U, An

Figure 48. Charleston Harbor, Oregon. Photograph courtesy of CH2M Hill, In

considered in the design of a s mall suggests that the shape of a boat basin
craft harbor. The design should be should fit water flow patterns of the
appropriate for local weather conditions, area. This means avoiding square-shaped
including precipitation, wind, ice, and basins that create deadwater areas.
fog for both durability and safety rea- Deadend canals or basins are not advis-
sons (Dunham and Finn 1974). Waves, ed. Basins should not be deeper than
shoaling, and geoloqical factors should the access channel (Florida Game and
also be considered. Freshwater Fish Commission 1975). Heiser
and Finn (1970) recommend the "flow-
According to Clark (1974), a site through desions" and cite Shilshole
with maximum natural protection will Marina as a good example (Figure 6).They
minimize alterations and the concomitant also suggest reducing stagnation by fac-
adverse impacts. Alterations, such as ing the entrance away from prevailing
dredging and contin ual maintenance, summer winds. According to Stockley
can be avoided by selecting a location (1974), open pile and floatinq breakwa-
with the maximum natural physical ben- ters allow the most water circulation in
efits (Florida Department of Natural Re- a marina. Proper circulation would mean
sources 1973). Bauer (1973) recommends the marina should be designed in length,
that marinas be located "...at the end width, and depth so that a large per-
of, or between drift sectors,or on self- centage of the water can be exchanged
contained pocket beaches..."to minimize each tidal cycle. Stagnant areas where
impact. exchange will not occur should be avoid-
ed. Culverts have been used in harbor
A concept presented by Ketchum construction to enhance circulation. If
(1972) states that one way of reducing proper circulation is not designed into
adverse impact on bay or inlet habitat the marina, then some type of flushing
is to construct the marina inland, con- mechanism should be provided. If dis-
necting it to the sea by canals. T his solved oxygen levels become too low,
is presently being done in some areas mechanical aeration may be necessary
of the United States (see Regional Con- (Environmental Quality Laboratory, Inc.
siderations). Inland marinas should 1977) although it is expensive and not
leave adjacent wetland communities un- as reliable as avoiding the situation in
disturbed (Florida Game and Freshwater the first place.
Fish Commission 1975). The Florida De-
partment of Natural Resources (1973), Several sources recommend alterna-
in their list of recommendations on ma- tives to bulkheading in marinas. Accord-
rina location and design, recommends ing to Carlisle (1977), rock breakwaters
that marinas caterin rimarily to craft with moorace along the piers in deeper
smaller than 24 ft ?7.P3 m) should use water are- preferable to bulkheaded
upland dry-storage facilities, rather areas. Slawson (1977) suggests that
than occupy water space. mooring piers be run into the water from
riprap edges rather than using bulkheads
The entrance channel should be at the water's edge. The section on
designed for safe navigation for vessels bulkheads should be consulted for fur-
expected to use the harbor. Sailboats ther information. With increased use of
may require different design conditions the harbor area, water quality may be
from power b oats. Narrow win ding threatened. Small craft harbors should
channels should be avoided and bends not be located near sewage or industrial
should be gradual (Dunham and Finn waste outlets (Heiser and Finn 1970).
1974). T raffic during busy periods Proper disposal of litter, sewage, and
should not cause excessive congestion runoff should be provided. Discarding
or danger. scrapfish, unused bait, and fish remains
in marina waters should be prohibited
One of the problems consistently (Heiser and Finn 1970). Regulations
mentioned in the literature was that of limiting the amount of toxic materials
proper water circulation and flushing that can enter the water from boats or
within a harbor. When designing a small marine structures should be enforced.
craft harbor, it is important that water Fuel should be stored and handled care-
circulation is assured. Wick (1973) fully to prevent spillage. Methods for

cleaning up accidental spills should be Expected-Life Span
provided ( Coastal Plains Center fo r
M a r! n e D ev elop m e nt Service 1973). The expected life span of a small
boat harbor was not discussed in the
Socioeconomic. Small craft harbors literature. The life span of a harbor
can be more economically placed in the is dependent on the durability of the
areas of low wave energy requiring few- various structures that make up the har-
er protective structures (Bauer 1973). bor, particularly breakwaters or jetties
This type of environment, which includes which protect the entrance channel and
estuaries, bays, and marshes, is also basin. Specific sections of this report
highly productive for natural resources. dealing with breakwaters and jetties
Therefore, the economic and biological should be consulted.
costs and be n efits must be weighed
when siting a marina. Summary of Physical and Biological
Impacts
Biological. During construction and
operation of a marina, any unnecessary Construction effects. Numerous ac-
disturbance of adjacent areas should be tivities can be involved in harbor con-
avoided. Wetland and marsh h a bitat struction depending on the features of
should be protected. Turbidity control the harbor. One should consult the ap-
devices should be used when necessary. propriate section of this report for in-
Vehicles designed to minimize soil com- formation pertaining to the impacts of a
paction should be used when working in specific structure. Major considerations
wetlands. Shellfish beds are mentioned are turbidity and the release of trapped
often as a p@rticular area of concern toxicants from sediments.
(Coastal Plains Center for Marine Devel-
opment Service 1973, Florida Department Chronic effects. The impacts of a
of Natural Resources 1973, Snow 1973). small craft harbor are dependent on site
Shoreline vegetation should be left in characteristics, the design of the har-
place and used to aid in shoreline sta- bor, and the extent of alterations that
bilization (Florida Bureau of Environ- were made on the environment (Clark
mental Protection 1975). Wetland areas 1974). Carlisle (1977) states that there
should be avoided as sites for fill and is generally no normal benthic succes-
surfacing (Clark 1974). sion, poor substrate, and poor water
quality in harbors. Ross (1977), on the
Giannio and Wang(1974) recommend other hand, maintains that marinas do
using dredge spoils from the marshes to not necessarily produce poor water cir-
establish new marshes elsewhere. Ef- culation and anoxic conditions. Although
forts should be made to create new hab- opinions varied in the literature, water
itats if possible. For example, riprap is quality should be considered during har-
recommended over bulkheading because bor design.
it provides better habitat for sessile
organisms. Biological impacts due to the
various structures contained in small The function of a small craft har-
boat harbors should be considered in bor dictates the need for calm water
the total harbor evaluation. (Refer to which can lead to stagnation and con-
the sections on Breakwaters, Piles and comitant water quality problems. Dead
Piers, Buoys, Floating Platforms, Ramps, end canals or basins with inadequate
Groins, Jetties, Bulkheads and Revet- flushing create stagnant water. This
ments. staanant water can experience larger
tem@erature and salinity changes than
Construction Materials adjacent areas. Wick (1973) st;tes that
the "square-shaped boat basins require
Harbors may contain one or more dredging and filling, and create dead
of the various small structures discuss- water areas - all adversely affecting
ed in other sections of this report. The the natural flow system." Poor circula-
other sections should be consulted for a tion of the water can lead to a buildup
discussion on the various types of con- of organic sediments and depletion of
stru ctio n materials used in harbors. dissolved oxygen.

R eis h (1963), in his studies of into deep water, predation is increased
Alamitos Bay Marina, discovered a drop (Rickey 1971). The loss of shallow wa-
in the benthic population in the basin ter areas for spawning and for nursery
area approximately one year after con- areas is of concern. However, according
struction. No significant drop occurred to Stephens (1977) harbors produce a
in the channel area. Reish (1963) sug- 'Imodified bay-like environment" condu-
gested that the decrease in the popula- cive to fish habitation. The breakwa-
tion was a result of limited water circu- ters, groins, jetties, and riprap are
lation. In this case the dissolved oxy- all considered to provide increased hab-
gen content decreased and the gray itat for fish or for the organisms on
odorless substrate became black and which they feed. Another possible advan-
had a strong sulfide odor. Carlisle tage is that harbor waters tend to be
(1977) explains a problem where har- warmer and may be preferred by the juve-
bors act as water traps creating condi- nile fish (Stephens 1977). Heiser and
tions suitable for dinoflagellate blooms. Finn (1970) observed that pink and chum
These blooms die off,causing a decrease salmon fry concentrated inside marinas.
in the dissolved oxygen levels resulting They also noted that the fry were more
in massive fish kills which in turn per- adaptable to this type of environment
petuate the lack of oxygen. and more resistant to predation than was
previously thought. Rather than school-
Water quality in a harbor is fur- ing and moving to shallower water when
ther affected by boating activities. Pe- disturbed in undeveloped beach areas,
troleum products are released into the the fry were observed to dive 3 to 5 ft
water from boats and trailers. The clar- (0.9 to 1.5 m) and swim away. When the
ity of the water is influenced by boat fish moved into deeper water to swim
traffic to varying degrees, depending around breakwaters or bulkheads, preda-
on the depth of the water (Bowerman tion was increased. However, Heiser and
and Chen 1971). A study of Marina Del Finn (1970) state that predation may
Ray by Bowerman and Chen (1971)show- have been less within the marina than in
ed that the shallower basins were gen- smaller natural beach areas due to the
erally not as clear as the deeper mid- increased "activities which tended to
channel water. The increased cloudiness discourage birds and larger fish species
can reduce light penetration, resulting' from attacking the salmon juveniles."
in reduced photosynthesis and oxygen
production. Cumulative effects. Cumulative ef-
fects of small craft harbors constructed
General increased usage can cause in wetland areas may include the elimi-
adverse effects in the area. P ote ntial nation of such areas as productive habi-
pollution problems exist from oil spills, tats. The impact on the environment
sewage disposal, land runoff, and ero- increases as the area covered by these
sion (U.S. Department of Commerce facilities increases. Decreased water
1976). Copper contamination can result quality and increased human activity
from protective paints on boats, floats, over a large area is not conducive to
and other marina structures or by the natural productivity.
treatment of hulls with copper-based
toxica nts. These factors, in addition to Structural and Nonstructural
a lack of water circulation, can create Alternatives
serious water quality problems. Accord-
ing to Clark (1974) the aquatic biota is Structural alternatives to the
endangered by the inability -of harbor small craft harbor can best be under-
waters to rid themselves of the "marina- stood by evaluating the individual com-
source contaminants." Noise and air ponents making up the harbor. A harbor
pollution may also disturb the aquatic can consist of breakwaters, bulkheads,
and terrestrial inhabitants of the area. piers, ramps, revetments, and other
structures, and each of these components
There is some question on the ad- has potential alternatives described
vantages and disadvantages of small elsewhere in this report. There are,
craft harbors in relation to fish. W here however, alternatives to the entire har-
harbors cause migrating fry to move bor which are described below.

One alternative to the harbor is Only 10% of California coastal wet-
the upland storage of small craft. This lands (Coastal Regions I and 2) remain
can either be accomplished by the indi- and much of the loss is attributed to
vidual owner retaining possession of the marinas (Slawson 1977). California laws
craft or a central storage facility being can prevent most wetland development, so
constructed. Such a facility would nor- marinas are now being built on uplands
mally be near a launching point. A with canals leading to the open water
means of launching is required before (Carlisle 1977).
upland storage is a viable alternative.
A ramp for use by trailer mounted craft There have been heavily contested
is most commonly used,but a crane sys- proceedings over the construction of
tem mou nted on a pier is also feasible. marinas and marina/residential develop-
The main constraint of upland storage ments in Florida (Coastal Regions 3, 4,
is that it is time consumino. It is also and 5).
quite expensive to launch larger ves-
sels. Upland storage is generally an BRIDGES AND CAUSEWAYS
alternative for small craft which trailer
easily. Definition

Alternatives for the larger vessels A bridge is a structure erected to
are individual piers or mooring buoys span natural or artificial obstacles,
located in protected areas. Generally, such as rivers, highways, or railroads.
a single well-placed boat harbor would A bridge supports a footpath or roadway
be a preferable alternative to a prolif- for pedestrian, highway, or railroad
eration of single moorages, but such a traffic (Figure 49). A bridge normally
decision can only be made after a site is built from steel, concrete, or wood.
examination. Bridges are supported by piers and abut-
ments. A bridge pier is a support struc-
Placement of small craft harbors ture in the water and should not be con-
inland of wetlands and tidal zones, with fused with other marine structures of
access by a dredged channel, may pre- the same name which serve as a landing
sent a desirable alternative as far as place for boats. An abutment is the
location is concerned. Again, all bio- structure supportinq the bridge at the
logical, economic, and navipation factors point where the lan-d meets the water as
must be weighed to make such a deter- distinguished from a pier which is whol-
mination. ly in the water.

Regional Considerations A causeway is a way of access, or
Most of the information in the lit- raised road, typically across marshland
or water (Figure 50). A causeway nor-
erature can be applied to all the coastal mally consists of a continuous solid
regions. There are some considerations, fill embankment constructed of earth,
however, that were mentioned in refer- sand, or rock dredged or dumped in the
ence to particular coastal regions. The water or on marshy land with a roadway
effect of small craft harbors on salmon or pathway on it. A causeway can have
migration was studied in the north Paci- culverts on open channels to allow cir-
fic (Coastal Region 1). This information culation and equalization of the water
may also be applicable to the Great heights on both sides of the structure.
Lakes (Coastal Region 8) where salmon
have been introduced. Salmon fry will Structure Functions
not go through culverts, so it is recom-
mended that gaps be provided in break- The basic function of both bridges
waters or other structures to allow the and causeways is to support some form of
passage of salmon fry to all tidal levels land transportation, such as foot traf-
without forcing the fry to enter water fic, highway, or railroad tracks. Where
over I ft (0.3 m) deep where predation the obstacle to be crossed is water or
may be increased (Heiser and Fin n marshy land, either structure can per-
1970). form the function satisfactorily. The

mown,

Figure 49. Many of the older bridges (top, center) along the Overseas
Highway to Key West, Florida,are being replaced by new structures (bottom).
Photographs by E. L. Mulvihill.

100

.map"

Figure 50. A bridge and causeway system
crosses Apalachicola Bay on the Gulf coast
of Florida. Photographs by E. L. Mulvihill.

101

-D

Figure 51. A silt curtain is used to contain sediment
produced by causeway work on the Overseas Highway in
Florida. Note the difference in water clarity on both
sides of the curtain. Photograph by E. L. Mulvihill.

102

choice between the two will usually be Where fill is used for support, the
based on economic, environmental, or ditches constructed throuah the causeway
hydraulic factors. In general, bridges may be an effective means to facilitate
will be used where there is deeper wa- tidal inundation. However, the movement
ter to cross, or where navigation or of water into and out of the wetlands
water passage and circulation must be behind the causeway may be altered as
maintained . Causeways will usually be compared to natural conditions due to a
economically attractive across ma rs hy loss of hydraulic drag. This condition
land or the shallow water portions of has probably occurred in the Florida
estuaries. Everalades due to channelization of wet-
land areas (Davis 1977). Clewell et al.
Causeways can be used in conjiunc- (1976) suggest considering the use of
tion with bridges. For instance, a many small culverts as opposed to ditch-
causeway can be used in the shallow ing to achieve natural flooding and
portion of a waterway and a bridge in drainage of a marsh area. Ditching will
the deeper portion where a causeway generally cause faster drainage of the
would be uneconomical or cause unac- marsh than would occur under natural
ceptable side effects to navigation or circumstances.
water circulation.
Socioeconomic. According to Gosse-
Site Characteristics and Environmental link et al. (undated), bridges through
Conditions marsh areas are more expensive than
causeways. They stated that the cost of
The environmental conditions in constructing a bridge is about four
which bridges and causeways are con- times that of constructing filled high-
structed are variable. The literature re- ways. When the estimated value of marsh
ferred to structures constructed across destruction. is added to the cost of a
marshes, tideflats, estuaries, and chan- causeway, they become one-half to three-
nels; but construction is not limited to fourths as costly as bridges. However,
these locations. Brldqes and causeways in view of hydrologic considerations,
extend from one shoreline to another more extensive use of bridges may be
over the terrestrial zone, through the justified (Gosselink et al. undated).
tidal or subtidal zone, and back to the Both bridoes and causeways may have a
terrestrial zone. significant aesthetic impact on the
coastal environment. Bridges and cause-
Placement Constraints ways are the major access modes from
mainland areas to barrier islands and
Engineering. Bridges and cause- beaches which are utilized heavily for
ways should be designed to minimize recreation.
changes in water circulation and flow.
Piers or pile support structures are Biological. When designing a road-
recommended over solid fill. Clear spans way, wetland areas should be avoided
are recommended over piers, if possible whenever possible. Existing dikes and
(Clark 1974). The inclined approaches levees should be used if feasible. If
should also be supported by piles as wetlands cannot be avoided, than care
opposed to fill to allow for "hich-stage must be taken to minimize biological im-
water passage" (Sauer 1973) or high pact. According to Gosselink et al. (un-
water caused by storms. Bridge piers dated),bridges cause less marsh destruc-
should be as streamlined as possible tion than causeways because bridges have
and piles should be adequately spaced less effect on water circulation. Steep-
to minimize the interference with water er causeway and bridge approach slopes
flow. According to Clark (1974), it may might also aid in reducing habitat de-
be necessary to enlarge the watercourse struction (Bailey 1977).
area to maintain the original cross sec-
tional area. * Bauer (1973) recommends Environmental disturbances should
locatin g bridges across straight chan- be minimized during construction. Mat-
nels rather than across meandering or ting and/or vehicles designed to prevent
shifting channel systems to avoid inter- soil compaction are recommended for use
ference with the dynamics of such a in wetlands. The turbidity control de-
system. 103 vices should be used if construction is

expected to result in the significant in- shifting due to stress. The potential
creases in turbidity (Figure 51). Con- exists for shiftina of sediments due to
struction roads should be designed to the weight of materials deposited during
cause the minimal adverse effects and causeway construction. In some cases, a
should be removed when construction is mud wave had been created which advanced
finished. The bottom grade should be ahead of the causeway construction.
restored to what it was before alteration
(Florida Game and Fresh Water Fish Chronic effects. The most prominent
Commission 1975). Dredging and filling chronic effects of bridges and causeways
should be kept minimal. Clark (1974) mentioned in the literature are an al-
advises segmental construction to avoid teration in current, velocity, and water
dredging for access. Gosselink et al. circulation patterns resulting from de-
(undated) also recommend against ac- creased cross sectional area. Salinity
cess canals. When solid fill causeways may be affected in estuarine environ-
are constructed, Gosselink et al. (un- ments and other areas subject to tidal
dated) recommended side casting to re- flow. Marsh circulation may also be af-
duce water quality degradation, long- fected. Concomitant alterations in the
term environmental damage, ad verse flora and fauna will be dependent on the
aesthetic impacts, and the time required degree of salinity change. Scour pits
for revegetation. If hydraulic dredges and deposition behind abutments may re-
are used they recommend disposal in sult where current velocity is increased
diked waste areas to facilitate settling by bridge piers and approaches (McAllis-
of suspended materials. ter 1977). Blocking of longshore cur-
rents and sedimentation may result from
Construction Materials causeways. This is shown dramatically
in Figure 52 where the silt laden water
Construction materials for bridges of the Fraser River is directed offshore
include steel, concrete, or wood. A by the deadend Roberts Bank Causeway in
causeway embankment may be construct- British Columbia. An atypical unturbid
ed from soil, sand, or rock. environment results between the Roberts
Bank Causeway and the more southerly
Expected Life Span Tsawwassen Ferry Terminal. This can be
highly detrimental to filter feeding
Information was not found in the benthos (Rounsefell 1972). Impoundment
literature about the expected life span of water upstream from a causeway can
of bridges and causeways. Both of adversely affect marsh vegetation, re-
these structures should be considered ducing the amount of plant biomass for
as extremely long lived and essentially the food webs and decreasino the value
a permanent change to existing condi- of the marsh as wildlife habitat (Sipple
tions. 1974a). The impoundment of water above a
causeway can lead to secondary environ-
Summary of Physical and Biological mental alterations, such as stream chan-
Impacts nelization to prevent flooding. A study
of the causeway in the Strait of Canso,
Construction effects. Construction Nova Scotia, revealed that the once dom-
activities are likely to cause increased inating tidal currents were superseded
turbidity and sedimentation, particularly by wind driven currents as a result of
when excavation and spoil disposal are the causeway. The currents were not only
involved. Spoil disposal may cause hab- slower, but also more variable. Salinity
itat loss, change in species composition, and temperature stratification were also
and water quality deterioration (Gosse- altered (Vilks et al. 1975).
link et al. undated). Revegetation is
almost impossible where sandy spoil is The weight of material used for
deposited and is slow and varia'ble when causeway fill can cause changes in the
spoil is tdken from brackish or saline elevation in adjoining areas. Marshlands
marshes ( G osselin k et al. u n dated are especially vulnerable to these types
of changes due to their relatively
Many aquatic and terrestrial sedi- spongy composition. Most wetland plants
ments are spongy and are subject to are very sensitive to changes in their

104

Jit

A@,

4@'

IVII

Vit.
to,

-77"

Figure 52. ;he Roberts Bank Causeway in British Columbia effectively divert
0
River silt laden water away from the shoreline. The causeway is about 2 mi
long. An environment atypical of the rest of.the delta has developed down c
of the causeway. The letter A marks the Roberts Bank Causeway, and B marks
Tsawwassen Causeway. The letter C indicates the Fraser River silt plume. T
denotes direction of flow. Photograph by the United States Geological Surve

elevation relative to water level. Such T here are several n onstructu ral
chanqes can affect marsh plant ecology. alternatives to bridges. One, of course,
An example is the different elevation is routing of the highway or railway
requirements of Spartina alter niflora over existing bridges or by circuitous
and S pa rtin a patens in northeastern routing not requiring a bridge. Another
marshes. nonstructural alternative is to use a
ferryboat instead of a bridge.
Causeways may possibly result in
disruption of fish and whale migration. Tunnels and rerouting are also al-
According to Brisby (1977), whale mi- ternatives to the causeways, although a
gration was slightly disrupted by the tunnel is so much more costly than a
causeway leading to Rincon Island, causeway that it is a theoretical rather
C alifor nia. than a practical alternative. Since the
causeways normally cross marshes or
Cumulative effects. The cumulative shallow water, it is unlikely that a
effects of bridges and causeways are ferryboat would present a viable alter-
referenced in the literature about the native in many instances. Structures
Florida Keys. The case study of this associated with ferryboats, such as
area should be consulted. piers, also have environmental impacts.
In addition, the convenience of a bridge
Structural and Nonstructural relative to a ferryboat is obvious.
TH-ernatives
Regional Considerations
Bridges and causeways can be de-
signed to respond to the physical and The only specific regional consid-
environmental surroundings in which erations mentioned in the literature
they are built. Bridges can be placed were in reference to the Overseas High-
on piling or piers shaped and spaced to way through the Florida Keys in Coastal
provide minimum interruption of altera- Region 4. The case study should be
tion of water flow. B rid ge spans can consulted for further information.
be designed with longer lengths to re-
duce the number of piers or support
structures in the water; however, a
long span length may make the struc-
ture more costly to build. Causeways
can be designed with culverts or open
channels through the structure to allow
water circulation. Causeways can be
replaced by open pile structures instead
of fill to allow nearly unhindered circu-
lation of water.

Besides various methods of design-
ing and building a bridge to alter the
impact,there are some alternatives avail-
able. The most common structural alter-
native to a bridge is a tunnel. After
construction,a tunnel provides no inter-
ference to water flow or circulation and
no interference with the substratum or
inter-tidal zone. If the tunnel is placed
in a dredge trench,there might be sub-
s ta ntial alteration of the substratum
during construction, as well as other
problems normally associated with the
dredging or underwater excavation. As
a general rule, tunnels are significantly
more expensive than bridges.

106

CASE HISTORY STUDIES

This section contains summaries of and another large storm drain outlet is
cases where shoreline structures have located to the south. The parking lot
been installed and the subsequent mod- storm drains e m pty into the basin.
ifications to the environment. Case his-
tories were selected to cover each of Heiser and Finn (1970) indicated
the coastal regions in this study and, that there was evidence of "impound-
where feasible, the structures which ment"; but because of the location of
cause permit review personnel in each the marina and the large entrance, the
region the most difficulty. Some of the tidal exchange was adequate for reason-
case histories are well- docu me nted, and able water quality. Problems might arise
others are very sketchy. In some cases from a spillage of petroleum materials
no information existed and hypothetical within the basin because the materials
case histories were formulated. In each would be held in the marina by winds
instance the case histories reflect the blowing north or south toward the sides
type of concerns that should sur-face in of the breakwaters. Observations by
the permit review process. Heiser and Finn (1970)showed that pink
and chum salmon fry were concentrated
CASE HISTORY - SMALL CRAFT HAR- inside the marina in greater numbers
BORS IN COASTAL REGION I -NORTH than along adjacent natural shorelines.
PACIFIC They do not know if the harbor acted
as a trap for the fry or if they prefer-
Information pertaining to a specific red the confines of the harbor.
harbor and location is not sufficient for
the presentation of an actual case his- Des Moines Marina consists of a
tory in Coastal Region 1. A significant sincle basin with a rubble mound break-
amount of the literature about small water leaving a dredged channel open-
craft harbors in Coastal Region 1 is re- ing facing north. The basin is dredged
lated to marina design and its effect on to -12.6 ft MLLW (-3.8 m). The surface,
water q uality and sal mon migration. area of the marina is approximately 20
Four marinas in the Puget Sound area acres (8 ha) and about 25% of the sur-
of Washington State will be compared to face is shaded by floating piers (Nece
illustrate the impact of marinas in the et al. 1975). Two residential storm
Coastal Region 1. The four marinas are drains and the parking lot drains empty
Edmonds Marina, Des Moines Marina, into the basin. The location of the en-
Kingston Marina, and Shilshole Marina. trance is not conducive to the tidal ex-
Maximum wave height in this area is change. Northerly winds are common in
approximately 6 ft (1.8 m). The tidal the summer and will cause interference
range is around 10 ft (3 m). Northwest- with the outward movement of the water
erly winds are common in the summer (Rickey 1971), resulting in stagnation
(Rickey 1971). at the southern end of the marina basin
(Heiser and Finn 1970).
Edmonds Marina consists of two at-
tached rubble mound breakwaters pro-
tecting two marina basins (Figure 53). Kingston Marina consists of a dog-
The entrance is located between these leg rubble mound breakwater extending
breakwaters. The shoreline is bulkhead- fro m the north shore, then angling
ed and two timber pile breakwaters ex- twice at approximately 45' to protect
tend from this bulkhead shoreward of the front of the marina. The south side
the entrance separating the two basins. of the marina consists of a large en-
The basins are dredged to -12 ft MLLW trance. Because of this large opening,
or -3.7 m (Nece et al. 1975). There the water quality of the marina is rela-
are 825 boat berths in the two basins tively good. The large open area allows
and about 25% to 30% of the surface is adequate tidal exchange and good move-
shaded by floating piers. The munici- ment of surface water out of the marina
pal primary sewage treatment plant out- with northerly winds (Heiser and Finn
let is located just north of the marina 1970). Heiser and Finn (1970) observed

107

PUGET SOUND N N PUGET SOUND

RUBBLE MOUND BREAKWATERS
k@\RUBBLE MOUND
BREAKWATER

TIMBER PILE BREAKWATERS TIMBER PILE
BREAKWATER

BULKHEAD

EDMONDS MARINA DES MOINES MARINA

C)
Co
N
PUGET SOUND R-,,,,DOGLEG RUBBLE PUGET SOUND
MOUND BREAKWATER
N @@,j@DETA HED R 8
W@Bf
MOU B@E T
@NDR AUK AER@

KINGSTON MARINA SHILSHOLE MARINA
Figure 53. Four different marina designs in Puget Sound, Washington. Diagrams are not to scale.

pink salmon fry within the marina in 1975b) Tides are diurnally une?ual
large concentrations. with a range of about 7.5 ft (2 m in
the bay (Terich and Komar 1973). Bay-
Shilshole Marina is designed with a ocea n peninsula, a narrow sand spit
detach ed rubble mound break water. about 4 mi (6 km) long, extends from
This allows for openings at both ends the channel entrance at the north end
of the marina, as well as good tidal ex- of the bay south to Cape Meares, a
change and surface water movement. rocky headland (U.S. Army Engineer
This design also facilitates easy passage District, Portland 1975b). Longshore
for salmon. c u rre nts are southerly from May to
November and northerly from January
Washington State Department of through April. Net littoral transport is
Fisheries (10,71) recommends the use of thought to be near zero. The tidal cur-
open structures, as opposed to solid rents at the inlet are strongly influenc-
fill, to minimize impact on fish and ed by the geometry of the inlet and bay
shellfish in this region. Where solid (Terich and Komar 1973).
structures are used, breaches should
be provided to allow salmon fry passage No prejetty data exist for environ-
without going into water greater than mental conditions at Tillamook Bay. The
12 in (30 cm) deep at all tidal levels. U.S. Army Engineer District of Por-tland
Shilshole and Kingston Marinas are more (1975b) described the present setting in
conducive to salmon fry migration be- its environmental impact statement on
cause they do not restrict passage to dredging and jetty maintenance. Water
the extent of Edmonds and Des Moines quality is moderate to high; local tur-
Marinas. Shilshole Kingston Marina has bidity is sometimes caused by high run-
a particularly favorable design with the off conditions in incoming rivers. No
detached breakwater allowing salmon complete inventories of fish and wildliff-
passage at both ends of the marina. resources of the area exist, although
considerable data are available. B oth
Edmonds Ma rina and Des Moines salt and freshwater fishes are present
Marina are examples of marinas with and the bay is a migration route for
11restrictive breakwaters" (Heiser and anadromous fis h. Herring and other
Finn 1970). They inhibit water circula- fishes spawn in the estuary. Dungeness
tion under normal circumstances and crabs, oysters, clams, and shrimp are
could result in rather serious effects if abundant, providing major recreational
a spillage of toxic materials occurred. activities. Eelgrass beds are found in
Marinas such as Kingston and Shilshole several areas of the estuary.
allow for more rapid dilution which can
reduce such hazards (Heiser and Finn The history of the two Jetties at
1970). Edmonds Marina has an added the mouth of Tillamook Bay, Oregon
disadvantage in that it is located close (Figure 54), is amply documented.
to a sewage outfall. Stockley (1974) Early diaries, photographs, newspaper
recommends that marinas not be located articles, and government documents
closer than one-half mile to primary describe the area before jetty construc-
sewage plant or industrial waste out- tion, following construction of the north
falls. jetty and after construction of the
south jetty. Unfortunately, these sources
CASE HISTORY - JETTY IN COASTAL of information neglect to depict the
REGION 1 - NORTH PACIFIC original biology or to describe biological
changes which have occurred over the
Tillamook Bay, located about 50 mi years. History of physical changes in-
(80 km) south of the mouth of the Co- fluenced by the jetties is easily found,
lumbia River, is Orecon's second larg- but changes in the biota must be infer-
est estuary. It is about 6 mi (10 km) red.
long and varies in width to a maximum
of 3 mi (5 km). Over half the area of A journal of an early explorer,
the estuary can be considered tidelands written in 1788, describes Tillamook Bay
(U.S. Army Engineer District, Portland (Terich and Komar 1973). The entrance

109

IN,

@00

i Ad

Figure 54. Tillamook jetties, Tillamook Bay, Oregon. Bayocean Spit extend
from the south jetty at center of the picture. Photograph courtesy U.S. Ar
Engineer District, Portland, Oregon.

was narrow, with a dangerous shoal and minimize undesirable effects of wave ac-
rapid tides. This situation continued tion on navigation and to eliminate the
through the nineteenth century. In 1888 necessity for artificial channel mainte-
the U.S. Army Corps of Engineers re- nance. The latter is usually achieved
ported that there was no reason to im- by either preventing littoral drift from
prove the channel entrance. Fifteen entering a channel or concentrating ebb
years later, the north jetty was propos- currents so that their natural scouring
ed to control the ebb current (Terich action is enhanced. Apparently neither
and Komar 1973). The north jetty was of these objectives has been achieved
completed to a length of 5,400 ft (1,646 by the Tillamook jetties. The channel
m) in 1917 at a cost of $776,000. It required dredging a few years after the
incorporated 429,000 tons (389,180 met- north jetty was constructed ( Kieslic h
ric tons) of stone. It was extended 300 and Mason 1975). In 1975, the Portland
ft (91 m) in 1933 (Terich and Komar District, U.S. Army Corps of Engineers
1973). No cost information on the exten- prepared an environmental impact state-
sion was found. ment for miscellaneous activities, includ-
ing channel dredging, in Tillamook Bay.
By 1921,four years after the north
jetty was constructed, the channel had Another factor in the construction
migrated to a new position against the of the south jetty was local desire for a
jetty, and dredging was later required means of halting erosion of Bayocean
to keep it open (Kieslich and Mason S pit. Following the extension of the
1975). The hazardous channel conditions north jetty, erosion apparently acceler-
ultimately led to the construction of a ated on the long, narrow sand spit
second, longer jetty on the south side (Terich and Komar 1973). Few records
of the entrance begin ning in 1969 were kept previously, so it is unknown
(Terich and Komar 1973). The south whether or not the construction of the
Jetty, completed in 1974, cost about north jetty increased erosion of the
@11.3 million (Anderson 1975). T otal s pit. It is known that the three-fathom
volume of stone used is not known, but contour moved 1,500 ft (457 m) closer
Anderson (1975) reports that it was to the spit between 1885 and 1939. This
considerably more than had been esti- caused increased nearshore wave energy
mated. This underestimation of material and concomitant erosion potential (Terich
required was largely due to problems and Komar 1973). Historical records
encountered during construction. show definite changes in the shoreline
both up and downdrift of the bay mouth
The jetty was built on the natu ral following construction of the north jet-
sand bottom. Though allowances were ty. Updrift sand accretion occurred
made for moderate sand loss due to the behind the jetty, while the shoreline of
crosscurrent scouring during construc- the downdrift spit retreated due to ero-
tion, the magnitude of this loss was sion (Komar et al. 1976). The spit
grossly underestimated. At the halfway eventually became so narrow that a
point in construction, the entire quan- storm in 1939 opened gaps which allow-
tity of bedding material had been used. ed the sea to enter the bay. In 1952, a
Strong currents around the advancing storm broke through and left a 0.8 mi
end of the jetty were washing out bed- (1.2 km) breach near the broad south
din material and sand to a depth of 30 end of the spit. This was later diked,
ft ?9 m) for about 300 ft (91 m) beyond but for some time there were essentially
the jetty tip. This problem was solved two entrance channels into the bay
in part by eliminating bedding material (Terich and Komar 1973). Recent infor-
and dumping large 200-lb (90-kg) to mation seems to indicate that erosion of
5-ton (4.5-metric ton) core stone direct- the spit has slowed since construction
ly on the sand bottom and by working of the south jetty (U.S. Army Corps of
double shifts to accelerate the construc- Engineers, Portland 1975).
tion process (Anderson 1975).
The effects of the Tillamook jetties
Kieslich and Mason (1975) state on the biota of the area can only be
that design objectives for jetties are to inferred since no quantitative before-

ill

and-after studies were made. Altered and bypassing of sand would serve this
currents within the estuary may have purpose. This would reduce the erosion
caused changes in sedimentation, salin- of the shoreline downdrift and accretion
ity, and water temperature patterns. u p d rift. Whether the weirs would lead
Erosion probably eliminated some sandy to the necessity for more frequent chan-
shore habitats, while accretion created nel dredging would require site-specific
others . The jetties provide a substrate stu dy.
for sessile and cryptic organisms and
fis h com mu nities associated with the Careful studies of potential effects
submerged structures. T u rbidity, caused should be conducted before jetty con-
by scour, may have affected organisms struction is begun. Too often an inlet
in the area, and the confined channel has been stabilized without thorough
may be a less than optimum environment knowledge of effects on other aspects of
for migrating smolts. the local environment.

In relation to the human environ- CASE HISTORY - BULKHEADS IN
ment,the presence of the jetties has ap- COASTAL R E G 10 N 2 - SOUTHERN
parently enhanced the area as a beach CALIFORNIA
recreation and sport fishing area. Stabi-
lization of the entrance channel allows Relatively little information was
fishing boats access to the harbor and available concerning the bulkheads in
the sandy area behind the north Jetty Coastal Region 2, except some general
provides clamming and fishing. The observations on the effects of bulkhead-
jetties are extensively utilized by fish- ing and the other protection measures
ermen. Erosion of the Bayocean Spit (Ploessel 1973, Carlisle 1977).
has been blamed on the presence of the
north jetty, so the loss of habitat and Bulkheads and seawalls are used in
real estate may be a negative impact. California for the same purposes as
elsewhere in the country. They contain
Channel maintenance dredging, in- lan dfill and protect the bulkheaded
clusion of weirs in jetties, bypassing of shoreline from erosion. They also pro-
sand, or no action at all are alterna- vide mooring.
tives to the construction of jetties such
as those of Tillamook Bay. If the inlet Effects of bulkheads and seawalls
is to remain navigable, the no-action on the biota of California are not well
alternative is eliminated from considera- documented, but a high incidence of
tion. Channel maintenance dredging dis- red tide has been observed in harbors
turbs the existing environment. Dispos- which have poor water circulation as a
al of dredge spoils on land or in the result of bulkheading (Carlisle 1977).
estuary is generally considered unac- There is obviously a loss of habitat in
ceptable and sea disposal preferable. areas which are filled, and intertidal
Thus, sand would be permanently lost communities may be severely affected if
from the area. Sand placed on down- a bulkhead is built below mean high
drift beach would cause some temporary water. Scouring at the foot of a bulk-
loss of habitat of intertidal organisms, head is a physical impact which affects
but might slow erosion on the Bayocean the benthic community in the vicinity of
S pit. Turbidity and resuspended sedi- the bulkhead. The vertical wall of the
ments could affect water quality. Fre- bulkhead may also inhibit migration of
quent dredging would be necessary and certain organisms from the water to the
costly. shore (Carstea et al. 1975a) or along
the shoreline.
If an inlet must be stabilized, it
appears that no acceptable alternatives Bulkheads and seawalls can have
to jetties exist. The impact of jetties on significant effects on human use of an
the physical and biological environment area. Bulkheads in industrial or resi-
could be lessened by reducing their in- dential areas may increase boat traffic
terruption of littoral drift. Weirs, plac- by providing mooring facilities. Seawalls
ed at intervals along a Jetty's length, on the open coast may restrict human

112

access to beaches and may result in A considerable amount of informa-
erosion of existing beaches. tio n is available in literature on small
craft harbors in Coastal Region 2. Ben-
The ecological effects of a bulk- thic studies were conducted by Reish
head or seawall may be considerable. (1961, 1962, 1963) from May 1956 to
Shorelines are often inherently unstable April 1962, regarding the benthic fauna
and the structure of their biological and fouling communities in Alamitos Bay
com m u nities reflects this instability. Marina following construction. These
The erosion which bulkheads are de- studies will be used as a base for a
signed to halt is a natural process to case history of Alamitos Bay Marina.
w hich the com m u nities are adapted.
Halting the erosion will alter the natural Alamitos Bay Marina is located in
com m u nities . Alternative structures, Alamitos Bay in Long Beach, California.
such as revetments of riprap, will also The first marina basin was dredged
alter natural communities by providing a from land beginning in late 1955. The
different type of substrate. However, basin was dredged to a depth of -12 ft
riprap has several advantages over sea (-3.7 m) mean low water and had a sur-
walls. Erosion of areas on the borders face area of 12.5 acres (5 ha). In early
of the riprap may not be as severe as 1956, after bulkheads had been con-
with bulkheads or seawalls. The major structed, the basin was filled with
advantage of a vertical structure over a water. Further dredging was conducted
properly installed revetment is the pro- in the central part of the basin. Boat
vision of mooring facilities or cosmetic mooring began in early 1957. Reish
treatment of the shoreline. (1961) reported results of benthic sam-
pling from May 1956 to August 1959.
When the bulkheads or seawalls are
proposed in this coastal region,adequate The substrate of the first basin
consideration must be given to a num- was originally gray clay containing bits
ber of important factors. First of all, of mica. In late 1957, black sulfide mud
given the existing littoral processes, was discovered at one of the sampling
determine where erosion and accretion stations. By summer of 1958, all sample
will occur after installation of the struc- stations had a layer of black mud con-
ture. If erosion or accretion in an im- taining a sulfide odor. This may be at-
portant habitat or navigable waters will tributed to poor circulation causing a
result,then one can anticipate additional decreased oxygen supply. The number
maintenance needs, such as beach nour- of benthic specimens collected varied
ishment or dredging,or the construction quite noticeably during the first 2.5 yr
of additional structures. Secondly, bas- of study with an increase after the ba-
ed on the expected physical impacts of sin filled with water followed by a pre-
the structure, determine which aspects cipitous decline. The lack of water cir-
of the biotic community will be affected culation may have been the cause of the
and the extent of the impact. For in- decrease in population that occurred in
stance, if an area containing the marsh the spring of 1957. Low oxygen levels
grass is to be bulkheaded and filled, were discovered above the basin floor.
many biotic effects can be predicted - Another possible cause of the benthos
such as reduction in the amount of pri- reduction is pollution caused by the
mary productivity by marsh grasses boats in the basin. Benthic species com-
and, consequently, a reduced crop of position within the basin was relatively
living and dead plant tissue for con- constant over the rest of the study pe-
sumption by other organisms. Valuable riod and there was no indication of suc-
spawning or rearing areas might also be cession. Sixty percent of the species
removed. Each situation is unique and and 87% of the specimens collected were
must be considered separately. polychaetes (Reish 1961).

CASE HISTORY - SMALL CRAFT HAR- In 1959, the dredging of three
BORS IN COASTAL REGION 2 - more basins and the main channel be-
SOUTHERN CALIFORNIA gan. Basins were dredged to -12 ft

113

(-3.7 m) mean low water, while the fishes, shellfishes, and other aquatic
channel was dredged to -15 ft (-4.6 m) life in the area.
mean low water. Cement bulkheading
and rock riprap were used for the sides C ASE HISTORY - BULKHEADS IN
of the marina. Benthic studies were COASTAL REGION 3 - G U L F OF
conducted by Reish (1963) from August MEXICO
1959 to April 1962, following the comple-
tion of dredging of the three additional Within the Gulf of Mexico, a num-
basins and the channel. No benthic ber of studies are available documenting
animals were found in the first samples the effects of bulkheads or seawalls on
taken following the dredging; specimens ce rta in components of an ecosystem
were found in samples taken in Septem- (Corliss and Trent 1971, Gilmore and
ber 1959. S pecies numbers increased Trent 1974, Mock 1966, Moore and
rapidly for the first 9 mo after that Trent 1971, Trent et al. 1972, 1976).
time, then held constant in the channel These studies are primarily concerned
for the following 14 wo (Reish 1962). with structures on the coast of Texas,
Over 50% of the species collected were but the results are generally applicable
polychaetes. Over the period of the along the Gulf coast of the U nited
study, no significant decrease in popu- States.
lation occurred after about I yr in the
first basin and in the inward portions The purpose of bulkhead or sea-
of the additional three basins. This wall construction in this region is to
drop in species was related to a drop in provide protection of upland areas from
dissolved oxygen and appearance of sul- erosion and also to provide waterfront
fide odor. These findings reinforced real estate. This latter function is
Reish's theory that poor water circula- achieved by constructing a bulkhead
tio n was the cause of the decrease, along a vegetated shoreline and then
since the water circulation in the chan- filling the area behind the bulkhead to
nel was not restricted. According to provfde land fo r develop me nt. Such
Reish (1963), it apparently takes about artificial creation of real estate is com-
1 yr for the effect of limited water mon in Galveston Bay, Texas, and in
movement to alter the benthic environ- Florida. Bulkheads also provide mooring
ment of a newly established marina. No facilities.
successional patterns of benthos were
observed. The creation of bulkheaded water-
front housing developments in this
Reish (1961) also observed that region has clear socioeconomic signifi-
succession of attached organisms did cance, regardless of the level of envi-
occur on the floats in the marina. The ronmental impact. Their success in pro-
apparent climax community of _@,Lt-qus viding desirable real estate is obvi(u-,.
and Ulva was noted after the floats had Alternate structures are generally not
been in the water for 6 mo. Up to 30 considered because of the economic ben-
associated species might have been pre- efits gained from filling behind a bulk-
sent. Reish (1962) notes that succession head or seawall. Their effects on coast-
on solid substrates in the southern Cali- al processes and the biota require more
fornia waters is more rapid than what detailed study.
has been observed in other geographical
areas.This may be due to longer breed- Trent et al. (1976) studied an area
ing seasons and relatively restricted in the West Bay of Galveston Bay, Tex-
annual water temperature ranges. as, which had been a natural marsh
before bulkheading. The marsh was
Because of the apparent correlation altered by channelization, bulkheading,
between benthic population decrease and and filling. The altered area consisted
poor water circulation, it is recommend- of a series of dead end canals with
ed that measures be taken to maintain houses built on the strips of land sepa-
proper circulation in marinas. Poor wa- rating the canals. Approximately III
ter circulation affects the benthic com- acres (45 ha) of emergent marsh vege-
munity and may also adversely affect tation (primarly Spar6na alterniflora),

114

intertidal mud flats, and subtidal areas organic nitrogen was highest in the
were converted into about 79 acres (32 marsh and may have been due to cattle
ha) of subtidal habitat by the develop- grazing near the marsh. Average total
ment (Trent et al. 1976). phosphorous was highest in the canals
of the housing development, but was
Phytoplankton prod u ctio n, oyster variable across time. Average levels of
production, benthic macroin vertebrates, dissolved oxygen and surface turbidity
fis h, and crustacean abundance were were lowest in the canals, and dissolved
studied in an open bay area, the bulk- oxygen levels dropped to extremely low
headed canal area, and in adjacent nat- levels at sampling stations farthest from
ural marsh area. Primary production of the bay during the summer months.
phytoplankton was higher in canal than
marsh areas, and production in both In general, productivity was high-
areas was much higher than in the bay er in the marsh than in canal areas and
(Corliss and Trent 1971). Oyster set- lowest in the open bay. Plankton blooms
ting was 14 times greater in the natural followed by low levels of dissolved oxy-
marsh than in a canal area. The faster gen, high nutrient levels, fish kills,
growth and lower annual mortality rates and depressed oyster, benthic macroin-
in the natural marsh were also reported vertebrate and shrimp production in the
by Moore and Trent (1971). Benthic summer months indicated the presence
macroin vertebrates were n u merically of eutrophic conditions in canal areas of
slightly more abundant and volumetri- the housing development. Moore and
cally over twice as abundant in the Trent (1971) noted that eutrophic con-
marsh than in the canals. The lowest ditions probably develop more rapidly in
abundance was in the bay. However, housing development canals than in nat-
when individual phyla were considered, ural marsh areas because of high nutri-
numeric and volumetric abundance var- ent levels, increased phytoplankton pro-
ied by area (Gilmore and Trent 13,74). duction, and a reduction in water circu-
More finfishes and crustaceans were lation and exchange.
caught in the marsh than in the canals
and catches were much higher in both Reduced productivity in bulkhead-
areas than in the bay. Brown shrimp ed canals may not be directly attribut-
(@enaeus aztecus), white shrimp (P. able to bulkheads, but rather to the in-
setiferus ) __@_n_ds pot (Leiostomus xan- creased human usage of the area and
thurusFwere most abundant in marsh; the removal of marsh habitat. Human
and largescale menaden (Brevoortia pat- use of bulkheaded and filled areas is
ronus),Atlantic croaker -_ (MicroRo2onias generally increased in terms of housing
i-ndulatus) and bay anchovy (Anchoa and boating.
mitchilliTwere most abundant in canals
7-Trent et al. 1972). These six species From a biological standpoint, bulk-
comprised 89% of the'total catch. Mock heading in this coastal region alters
(1966) compared penaeid shrimp produc- existing communities and may eliminate
tion in a bulkheaded and natural area some species entirely. The energy base
in another area of the Galveston Bay of the community changes considerably
system. He found greater shrimp pro- with the elimination of marsh grasses.
duction in the natural habitat. There are no satisfactory alternative
structures for the creation of new real
Numerous physical differences be- estate. However, existing land may be
tween the altered and unaltered marsh protected from erosion by the use of
areas were noted. Substrates in the revetments or by planting vegetation.
canal areas had a higher silt and clay When placing bulkheads or seawalls, it
content than the marsh, and the amount is desirable to locate them as far upland
of organic detrital materials in marsh as possible, preferably above mean high
substrate was twice that found in the water.
canals (Trent et al. 1972). Average
temperature, salinity, total alkalinity, CASE HISTORY - CAUSEWAYS IN
and pH were similar between the marsh COASTAL REGION 3 - G U L F OF
and canal areas. The average dissolved MEXICO

115

The information available about unculverted fill-road built 38 yr prior
causeways in Coastal Region 3 is very to the study. The roadway has blocked
limited. Clewell et al. (1976) conducted the sheet flow so that the marsh (Levy
a study of seven fill-road sites on the Pond) contains fresher water than the
northern Gulf coast of Florida. Sites tidal creek on the other side of the fill-
were located in five tidal salt marshes road. Photographs taken from years
in Wakulla, Taylor, and Dixie counties. after construction showed that various
This study will be used as a case his- salt-intolerant plant species have grown
tory of causeways in Coastal Region 3. in Levy Pond. No vegetation can be
seen in similar ponds on the seaward
According to Clewell et al. (1976), side of the road. At the time of the
tidal marshes in the area studied exist Clewell et al. (1976) study, Levy Pond
"where waves penetrate only during se- was "completely choked with cattails,
vere storms and hurricanes." Marshes saw grass, and other emergent marsh
are periodically flooded as a result of species, all characteristic of fresh water
tidal sheet flow. The height of high or very slightly brackish h a bitats. "
tide is dependent on lunar positions and The Evans Creek site contains a
is, therefore, variable. A marsh located fill-road,built 38 yr prior to the study,
at a higher elevation may not be inun- that traverses a tidal creek (Evans
dated as often as one at a lower eleva- Creek) approximately 0.5 mi (1.3 km)
tion. The sites that are inundated daily from its mouth. The salt marsh on the
usually have a uniform salinity similar landward side is isolated from the creek
to that found in tidal creeks or rivers. except for a box culvert (5 x 5 ft or
Sites not flooded daily have a higher 1.5 x 1.5 m). The creek was ditched
salinity due to evaporation. Sites high to facilitate tidal inundation of the land-
enough in elevation to receive more ward side of the road. Only slight dif-
fresh water from runoff and rain than ferences in salinity, animal density, and
the salt water inundation have low salin- vegetational zonation were discovered
ities. The vegetation is dependent upon between the landward and seaward side
the salinity levels of the site. of the fillroad, Clewell et al. (1976)
The distribution of three mollusc state that it is uncertain if these dif-
species sensitive to particular regimes ferences are due to the roadway or if
of salinity and inundation were studied. they always existed between the two
These species reacted to disturbances areas. It is suggested that the ditching
by alterations in density. Plant zonation "increased the frequency of tidal flood-
was also determined along with salinities ing but decreased the length of time
and elevations. that the marsh was inundated in each
tidal cycle." They suggest that culverts
The Porter Island site involves a might be substituted for ditching to
paved fill-road built 22 yr prior to the maintain more natural inundation and
study that traverses a 1.5-mi (2.4-km) drainage in such marshes.
long marsh protruding into Apalachee The Cedar Island study involves a
B ay. The fill is not culverted. The north and a south marsh. The two sites
only opening consists of a 25-ft (7.6m) are landward of a fill-road, built 8 yr
long bridge span. Fill canals run along prior to the study, that runs parallel to
the entire length of a roadway on both the coast 0.3 mi' (0.5 km) inland. The
sides. The study revealed that other north site can only be inundated by the
than the presence of the roadway and sheet flow. Only one culvert opens up
canals, the marsh environment was not to the seaward side of the road. A
adversely affected because tidal inunda- ditch and tidal creek flowing into a cul-
tion occurs independently on both sides vert allow inundation at the south site.
of the unculverted marsh since it is The results of the study indicate that
bounded by A palachee Bay on both sheet flow was blocked at the north
sides. marsh except when severe storms occur-
The Levy Pond site consists of a red. This allowed for the invasion of
marsh separated from a creek by an salt-intolerant species. The effects of
116

the fill-road and ditching in the south source of information is "Negative De-
marsh appeared to be similar to the claration State Road 5 (U.S. 1) Bridge
Evans Creek site. Replacements" ( H . W .Lochner, Inc.,
Consulting Engineer 1975).
Two sites were also investigated at
Cow Creek. Both of the sites are land- Around the turn of the century,
ward of a fill-road completed 4 yr prior Henry N. Flagler, one of the founders
to the study and parallelinq the coast. of Standard Oil and builder of the Flor-
What is referred to as the "open area" ida East Coast Railroad from Jackson-
is 1 mi (1.6 km) from the Gulf along ville to Miami, decided to extend his
Cow Creek. The study area is connect- railroad to Key West. The resulting
ed to the seaward side by a 6-ft(I.8-m) single track Overseas Railroad, complet-
wide culvert. Salinity, plant zonation, ed in 1912, covered a distance of 156 mi
and pattern and abundance of molluscs (251 km). In September 1935, a hurri-
were the same on both sides of the road cane washed out the track and roadbed
and are, therefore, assumed to be unaf- in the 30-mi (48-km) stretch from Key
fected by the fill-road. Vaca to Plantation Key. It was decided
that the railroad would not be rebuilt.
What is referred to as the "closed
area" is approximately 0.8 mi (1.3 km) 0 verseas Road and Toll B rid ge
from the Gulf. A 3-ft (0.9-M) wide and Commission purchased the right-of-way
12-ft (3. 7m ) wide culvert facilitates the and the associated physical assets and
drainage. Fill canals are located on both directed their efforts toward converting
sides of the roadway. Sheet flow ap- the remaining rail ro a dstructures to
pears to be restricted from the land- highway structures. The new highway
ward side of the roadway, as evidenced was opened to Lower Matecumbe Key in
by the presence of salt intolerant spe- 1936, to Big Pine Key in 1938, and to
cies. Clewell et al. (1976) state that Key West in 1944. The bridge-causeway
the canals are intercepting much of the system supplies access between mainland
incoming tidal water. and Keys for residents and vacationers..
It carries an aqueduct which assures a
Clewell et al. (1976) conclude that supply of fresh water to the Keys.
if the tidal flow through a fill-road is
unrestricted, marsh will not be signifi- Many of the bridge structures
cantly affected, other than within the have deteriorated severely since con-
area where construction of the fill-road struction more than 30 yr ago. Between
took place. 1963 and 1973, a total of $10,000,000
was spent for bridge repair. This sum
CASE HISTORY-BRIDGES AND CAUSE- equals the original cost of the highway
WAYS IN COASTAL REGION 4 - SOUTH system. It is estimated that maintenance
FLORIDA costs for the period from 1975 to 1985
will be $84,000,000. In 1974, Congress
The State of Florida Department of passed a highway bill which appropriat-
T ra ns portation (FDOT) in cooperation ed $109,200,000 for the replacement pro-
with the U.S. Department of Transpor- ject. In addition to the positive cost-
tation - Federal Highway Administration benefit analyses between replacement
(FHA) contemplates replacing 37 of the and maintenance, there is definite con-
44 bridges along 87 mi (140 km) of the cern that the deteriorating structures
Overseas Highway (State Road 5,U.S.1) might experience structural failure, pos-
from Key West to Key Largo. The local- sibly causing loss of life or serious in-
ized impacts due to construction and jury. It would also result in loss of
operation and regional impacts due to access between the Keys and the main-
cumulative affects of the many bridges land, as well as possible health hazards
and associated causeways make an inter- in the Keys due to a loss of the potable
esting case history study. Impacts dis- water supply.
cussed in this case history study will
be limited to terrestrial and aquatic im- The proposed reconstruction pro-
pacts. U nless otherwise noted, the ject will replace 37 of the 44 bridges
117

which represents approximately 17 mi tem peratu re changes of 10' to 15'F
(27 km) of the 18 mi (29 km) of bridges (5.6' to 8.3 C) during part of the year
in the Overseas Highway. Of the 37 (Davis 1977). This large diurnal tem-
bridges proposed for replacement,27 are perature fluctuation does not occur in
the spandrel arch type, one consists of the ocean. The difference in solar
spandrel arch and pier sections, and energetics in the Bay as compared to
the remaining 9 are composite pile type the ocean is probably also a factor con-
(Figure 49). The proposed bridge re- tributing to the salinity differences.
placement will also involve the recon-
struction of approximately 21 mi(34 km) The Florida Keys contain more
of bridge approach. About 11 to 33 endangered, threatened, and rare plant
acres (5 to 13 ha) of submerged land and animal species than any other re-
will be filled. gion of the State. Thirteen major parks
and wildlife refuges lie partially or
The Florida Keys are composed of wholly within the Florida Keys.
flat limestone formations with elevations
ranging up to 15 ft (4.6 m) above mean The extensive emergent mangrove
sea level. About 95% of the land is less forest and submerged turtle grass beds
than 5 ft (1.5 m) above mean sea level. are vital habitat for the propagation of
Shoal water commonly ranges up to 0.5 commercially and recreationally impor-
mi (1.3 km) offshore. Shoals are gener- tant species of fishes, shellfishes, and
ally composed of the mangrove swamps, wildlife. Availability of habitat is the
submerged turtle grass beds, and ex- limiting factor for these populations.
posed limestone with little or no soil. Protection of habitats is paramount to
protection of plant and animal species.
The islands lie just north of the
Tropic of Cancer, with Key West being After a lengthy series of public
the southermost city of the contiguous hearings, advisory committee meetings
United States. Key West is closer to with concerned residents and Federal,
Cuba (90 mior 145 km) than to Miami State, and local agencies, FDOT and
(154 mi or 248 km). Hurricanes, which FHA issued a "Negative D ecla ratio n
occur frequently in the Florida Keys, State Road 5 (U.S. 1) Bridge Replace-
are probably the most significant clima- ments" (H. W. Lockner, Inc., Consult-
tological feature of the area. ing Engineer 1975).

The chain of 97 islands separates The negative declaration evaluated
Florida Bay on the Gulf of Mexico side each bridge site separately, considering
fro m Florida Straits on the A tla ntic the following alternatives:
Ocean side. Relatively deep channels
between the keys transport water be-
tween the Gulf and Atlantic Ocean. It A. Continue to maintain existing
was estimated that the construction of bridge;
the original railroad system reduced the B. Remove existing bridge and
cross-sectional water area between is- construct new bridqe on or
lands by more than 50% (Bailey 1977), near existing alignment;
which reduced water exchange between C. Composite causeway struc-
Florida and the Atlantic Ocean. Salini- tu re;
ties in the upper portion of Florida Bay D. Construct new bridge on Gulf
are greater than 50 ppt for 9 to 11 mo or Atlantic side of old bridge.
of the year, as compared to 34 to 37
ppt in the Atlantic Ocean (Davis 1977). Alternative A was easily eliminated
There are no historical records, but based on economics and safety. Alter-
reduced flow between Florida Bay and native C was carried to the final eval-
the Atlantic Ocean may be a factor con- uation stage on nine bridges, but was
trib utin g to the salinity difference eliminated based on possible ad verse
(Bailey 1977). Florida Bay system is impact on natural and human environ-
shallow as compared to the contiguous ments. Alternative B or D was chosen
Atlantic Ocean and experiences diurnal for each bridge on a site-specific basis.

118

The environmental impacts address- 0 Construction and maintenance of
ed in the negative declaration were new bridges will be according to
mostly localized in nature. They did, State Standard Specifications for
however, emphasize the role of habitat. "Prevention , Control and A bate-
Features of the project related to ter- ment of Erosion and Water Pollu-
restrial and aquatic ecological impacts tion. "
that were addressed include 0 The use of sediment traps during
co nstru ction will be considered.
0 No unique vegetation will be re- 0 Interim use of webbing, matting,
moved. mulching, and other mechanical
0 Some submerged land will be filled. means of erosion control will be
0 Revegetation will be, considered. provided for.
0 Net impact of filling kept at a min- 0 Consideration will be given to
imum by increasing bridge length s pecial s pecificatio ns fo r b rid g e
and utilizing steep side slopes on de m olitio n and material disposal.
approaches. 0 Consideration will be given to ap-
0 Control of turbidity due to con- p rop riate locatio n of parking.
struction will be studied. 0 Where manoroves are impacted,
0 Borrow from dry land will be pre- th eir associated organisms can
ferred as compared to borrow from move elsewhere.
submerged lands and from the pre- 0 Retaining mangroves on the ocean
viously disturbed areas as compar- side will be more important than on
ed to new areas. the Bay side because of their rela-
0 Offshore dredging for fill in vicin- tive scarcity and wave protection
ity of bridges not anticipated ex- function on the ocean side.
cept where construction dredging
may be required.
0 If submeroed borrow operations Many of the foregoing considera-
were unde@taken, containment of tions can be considerea as directed at
the "dredge plume" would be an localized impacts. After release of the
important concern. negative declaration, FDOT negotiated
0 If dredging of marinas from the with concerned natural resource- agen-
onshore areas is done, no connec- cies about regional considerations.
tion should be opened until turbid-
ity has dropped to safe levels. Several agencies felt that FDOT
0 Holding borrow site depth to ap- was missing a good chance to return
proximately 20 to 25 ft will be con- the circulation patterns between Florida
sidered. Bay and the Atlantic Ocean to the pre-
0 Width of the fill will be minimized vious state that had existed before the
by using steep slopes. Flagler railroad was constructed. As
0 Structural retaining systems w ill m e ntio n e d before, cross-sectional area
be considered in some locations to between islands was reduced more than
reduce the area of bottom filled. 50% by that projject.
Sheet pile walls or tie-back types
will probably not be used due to All concerned individuals seem to
potential washout. agree that the salinity difference is
0 Air quality standards will not be real, but that the contribution of the
violated. causeway to this situation is not known.
0 Where FHWA exterior noise criteria Natural physical differences between the
are expected to be exceeded, ex- two bodies of water are probably a sig-
ceptions will be requested. nificant causative factor. Channelization
0 It is improbable the runoff from of the Everglades in 1962 and resultant
bridge or road sur-faces would vio- alterations of fresh water outflow to the
late State water quality standards. Florida Bay is probably also affecting
0 The possibility of spillage of toxic the salinity regime (Davis 1977).
materials from trucks will be re-
duced because the road will be There is definitely not agreement
safer. on whether increased flow between the

119

two water bodies would result in an of a potential remedial action for the
overall benefit. hypersalinity problem in Florida Bay.
The first phase will include studies to
Davis (1977) stated that there determine the relative contribution to
have been changes in the salinity of the the hypersalinity of the causeway area,
estuarine areas of the Everglades from natural physical processes, channeliza-
0 to 12 ppt prior to 1940, up to 25 to tion of the Everglades, and other fac-
40 p pt presently. This has probably tors. It will also determine the possible
changed the nursery eround function of results of various measures to alleviate
affected areas, but the nature of the the problem. The second phase of the
changes is not known. study will be to project the biological
consequences of possible remedial
Numerous years of data show that actions, such as increasing the flow be-
the year-class strength of redfish in tween the Keys.
Florida Bay proper is positively corre-
lated to high salinities in the spring, Another major concern regarding
whereas the year-class strenoth of sea the project is that valuable turtle grass
trout is positively correlated lo low sa- beds will be directly and indirectly (sil-
linities in the spring. Alterations in tatio n ) affected by dredging. After
sprinotime salinity might constitute a several meetings it was agreed that
tradeoff between the population levels FDOT would mitigate turtle grass losses
of these two fishes. acre for acre (Bailey 1977, Hall 1977).
The FDOT has conducted a study to de-
Pink shrimp and spiny lobster pro- lineate the turtle grass beds as they
vide the two largest comrr-.,ercial catches presently exist. A comparable study
in Florida. They are both highly de- after construction will define the acres
pendent upon Florida Bay as a nursery. of turtle grass that will be mitigated.
Recreational species, such as bonefish
and tarpon, are also very dependent Most of the shoals bordering the
upon Florida Bay as a nursery. The Keys co ntai n flat limestone bottoms
effect of salinity changes in the produc- which do not have unconsolidated sedi-
tion of these important commercial and ments and are, therefore, not suitable
recreational organisms is not known for turtle grass growth. During an in-
(Davis 1977). terview with F. Bingham of the Florida
Department of Transporation, it was
It has been observed by Davis pointed out that some of the best turtle
(1977) that the best coral reefs along grass beds in the Keys are in the old
the Florida Keys occur at the northern borrow pits which resulted from the
extremity where exchange of water with construction of the railroad and original
Florida Bay has always been minimal. causeway (Figure 55). The depth of the
John Pennecamp National U n derwater borrow pits fosters sedimentation of or-
Preserve is known worldwide and is lo- ganic material which serves as an excel-
cated in this area. Coral is known to lent turtle grass substrate. It is n ot
be very sensitive to altered salinities, known, however, how long it takes for
temperature fluctuations, and turbidity the turtle grass to establish itself in
and siltation. Waters flowing from Flor- borrow pits (Hall 1977). The depth of
ida Bay to the Atlantic Ocean through the borrow pit probably affects its suit-
the Keys' channels are high in salinity, ablility for turtle grass growth and the
have large temperature fluctuations and time period necessary for turtle grass
are relatively turbid and silty due to establishment. The acre-for-acre mitiga-
wave action in shallow areas. If water tion of turtle grass beds might possibly
circulation was increased between Flor- be accomplished by dredging a flat lime-
ida Bay and the Atlantic Ocean, there stone bottom and allowing sedimentation
might be resultant impacts u.pon coral and turtle crass establishment.
reef communities.
Environmental concerns surround-
The FDOT has agreed to conduct a ing the bridge replacement are many.
two-phase study of the possible causes Nearfield effects are somewhat classical

120

ROADBED

FILL DESIGN WATER LEVEL

BORROW AREA

SEDIMENTATION
E S @IG N @=A T E @=L E V E @L@@
A4

Figure 55. Cross-sectional view of a causeway constructed with fill material from a nearby borrow area.
The sedimentation in the borrow area can foster seagrass growth in some situations in the Florida Keys.

of construction projects in the coastal dynamics in this coastal region. A
environment. The farfield effects, such hypothetical island is nearly breached
as the potential contribution to hypersa- at one point, so a groin is built down-
linity and associated ecological modifica- drift to cause accretion at the weak
tions, are not as well known. It is a rea. The construction of the groin
probable that potential effects of cause- approximately 50 ft (15 m) long by 5 ft
ways on the marine environment will be (1.5 m) wide causes little environmental
debated for many years. At present damage because it is small. Turbidity,
the key issue controlling the replace- destruction of b otto m habitat, and
ment project is the potential loss of life beach disturbance are minor when view-
or serious injury that could result due ed in light of the extent of nearby
to structural failure. shoreline.

CASE HISTORY - GROINS IN COASTAL There are effects which do not ap-
REGION 5 - SOUTH ATLANTIC pear immediately. The groin interrupts
the littoral transport of sand, causing
Coastal recdon from Cape Canaveral it to accumulate updrift. The beach
to Cape Hatteras is characterized by updrift of the groin grows higher and
barrier islands, marshes, and estuaries extends out nearly the length of the
( Virginia I nstitute of Marine Science structure. The updrift area is protected
1976). The barrier beaches are long, from. erosion forces by a broad expanse
narrow sand beaches separated from 6e of sand. This does little harm to the
shore by embayments of varying widths resident organisms because it is a slow
up to 30 mi (48 km). Mlost of the shore- accumulation process and not different
line lacking barrier beaches is also from that to which they have adapted.
sandy and flat and is broken by estuar- The beach recedes downdrift since its
ies and tidal marshes. The sand is fine normal supply of sand now lies updrift
and is easily transported by the sea. of the groin. If unchecked, it will re-
The natural beac h erosion res ultin g cede until a breach occurs and the sea
from the storms and tides has been ac- flows into the lagoon. The natural pro-
celerated by the often carelessly plan- cess has, therefore, been displaced in
ned placement of shoreline structures, time and space. To protect the human
such as groins, bulkheads, Jetties, and investment, another groin is built and
breakwaters (Bruun and Manohar 1963). another until the barrier beach is en-
tirely protected by a vast groin field.
Some assumptions can be made Each time a minor amount of damace is
about an undisturbed barrier island a done to the environment, a few square
mile or more in length and separated feet of habitat is lost. However, in the
from adjacent islands by wide inlets. mile of barrier beach, there could even-
N atu ral processes will cause erosion tually be as many as 50 groins. The
and accretion of sand at various points; amount of habitat lost becomes more
the storr. winds and tides will break sionificant.
through islands, opening a channel into
the lagoon while the other channels will One little discussed effect of beach
close. The barrier islands will, over stabilization on barrier island systems is
time, change in shape, size, and topo- that of changing the physical and chem-
graphy. The plants and animals found ical characteristics of the estuaries and
there will, as they always have, adapt embayments lying behind the barrier
to these chances. Unfortunately, man is islands. Periodic wave overwash or
often not. tolerant of normal shoreline dune breaching allows seawater to reach
dynamics. Beaches must be stabilized behind the islands, causing salinity var-
to provide recreation, real estate, in- iations. Plants adapted to such an alter-
dustrial sites, or harbors. ed environment survive, while others do
not. When the beach is stabilized, suc-
Insufficient data were available to cession is toward plants not well adapt-
provide a case history, so a hypotheti- ed to oceanic conditions (Dolan et al.
cal situation was developed to demon- 1973). The advantages or disadvantages
strate the effects of groins on shoreline of this situation @epend on what is
.122

desired as an end result for that coast- behind the bulkhead; however, unpro-
al area. The tradeoffs involved are dis- tected areas adjacent to the bulkhead
cussed by Dolan (1966) and Dolan et al. may be eroded, and this can undermine
(1973). Altered salinity regimes in the the bulkhead from the sides. C a rstea
em.bayment can also affect life cycles et al. (1975a) claimed that bulkhead con-
and productivity of various aquatic or- struction would have a positive effect
ganisms, although this has been little on water q uality by stabilizing the
stu died. shoreline and reducing erosion. How-
ever, Gantt (1975) stated that scouring
C A S E HISTORY - BULKHEADS IN may cause erosion at the toe of the
COASTAL REGION 6 - FIDDLE bulkhead and that unprotected adjacent
ATLANTIC shorelines may erode because of the un-
dissipated wave energy resulting from a
Within Coastal Region 6, a number bulkhead. Carstea et al. (1975a) con-
of references are available on effects of ceded that the roughness coefficient will
bulkheads (Carstea et al. 1975a, Gantt indeed decrease slightly with bulkheads
1975, Yasso and Hartman 1975, Chesa- yielding an increase in the velocity and
peake Research Consortium 1974, 1976, the dispersion coefficient of the water,
Givens 1976). Most of the existing in- but stated that, if properly constructed
formation refers to Chesapeake Bay, and maintained, bulkheads will have no
but Yasso and Hartman (1975) discussed sianificant effects upon erosion, sedi-
bulkheads in the New York Bight. The mentation, or deposition. On the other
observations contained in the literature hand, one can expect alterations to lit-
are broadly applicable within this re- toral drift and currents, according to
gion, even though specific flora and Gantt (1975). Carstea et al. (1975a)
fauna will vary from location to loca- maintained that a small timber bulkhead
tio n. would produce no significant increase or
decrease in the storage capacity of the
Bulkheads in this region are used water body and no additional drift pro-
primarily to protect upland areas from blems. The differences in the conclu-
erosion and to stabilize the existing sions of these authors are considerable,
shoreline. Construction of bulkheads but may revolve around a different per-
with either steel or wood sheeting is ception of what constitutes a "signifi-
common. cant effect. " Furthermore, a single
small bulkhead, such as the one consid-
Impacts in this region due to con- ered by Carstea et al. (1975a), will
struction of a typical 150-ft (46-m) tim- have much less of an effect by itself
ber bulkhead and the associated dredg- than will many small bulkheads taken as
in g of 300 y d 3 (274 m 3 ) of fill were a whole.
considered in a theoretical case history
by Carstea et al. (1975a). In this case, Biological impacts of bulkheads are
it was expected that there would be no dependent primarily on the location of
significant impact on water quality. The the bulkhead, with upland locations pro-
increased turbidity would not affect wa- viding the least damage. Construction
ter quality significantly. There would below the mean high water line is more
be minor air quality and noise construc- damaging, and construction below mean
tion impacts, and some organisms would low water is most damaging. Filling be-
be directly eliminated by dredging and hind a bulkhead will destroy organisms
b u rial. located there. Isolation of marsh grass-
An alternative to the bulkhead con- es from tidal waters will cause a loss of
part of marsh grass community (Carstea
struction is the use of a revetment. et al. 1975a). Loss of wetlands will re-
However, bulkheads provide mooring sult in the loss of detritus production,
facilities which may be desirable in some storage, and transfer of nutrients; loss
situations. of feeding, breeding and nursery areas
for fish, shellfish, and the other organ-
Once in place, bulkheads . provide isms; loss of flow regulation and shore
p rote ctio n for upland areas immediately stabilization; and loss of habitat for the

123

waterfowl and terrestrial species. Gantt To afford maximum protection to the
(1975) noted the destruction of fringe coastal ecosystem each bulkhead should
marsh and shoreline when dredging oc- be considered not as a single isolated
curs, along with a reduction in species structure, but rather as an addition to
diversity in the zone near shoreline; an ever-growing complex of shoreline
nutrient cycle changes leading to lower structures.
water quality; high oyster mortality in
the vicinity of the bulkhead; reduction A possible alternative to bulkhead
in invertebrate production; and preven- construction is the placement of riprap
tion of recolonization by scouring action or other types of revetments, but these
in front of the bulkhead. Wolcott (1977) structures also have environmental con-
reported that bulkheads prevented the sequences. If mooring facilities are de-
ghost crab (Ocypode quadrata) from sired, small piers may be substituted.
reaching dune areas where they burrow
during cold weather. C A S E HISTORY - SANDBAG SILL
BREAKWATERS IN COASTAL REGION
A bulkhead provides docking facili- 6 - MIDDLE ATLANTIC
ties; however, it limits recreational ac-
tivities associated with a natural coast-
line (Carstea et al. 1975a). According Sandbag sills are being tested un-
to Carstea et al. (1975a), even a small der the auspices of the Virginia Insti-
bulkhead will cause erosion of sand and tute of Marine Science as alternatives
shallow water on neighboring beaches. to, or complements of, groins in the
Eliminating the littoral zone may reduce Chesapeak Bay (Greer 1976). No quan-
productivity in an area and thus affect titati v e biological stu dies were found
fishing. They estimated that there was and only a minimum of other information
generally little or no socioeconomic im- exists. However, since they ar@e poten-
pact of bulkhead construction in this tially a viable alternative to groins as
region. shore protection devices, their use can
From a biological standpoint, bulk- be expected to increase.
heads are generally not desirable struc- Chesapeake Bay has a long history
tures in this region. Reduction in the of shoreline erosion, primarily resulting
amount of marsh grass (Spartina alter- from wind-generated wave action. Slow-
niflora, S. patens) will result in a tang- ly rising sea level also contributes to
ible los the estuarine productivity. this problem. Greer (1976) reports that
Carstea et al. (1975a) estimated that a the 270 million cubic yards (249 million
150- ft (46-m) timber bulkhead, assum- cubic meters) of material were eroded
ing a width of 20 ft (6 m), would de- from Virginia's Chesapeake Bay shore-
stroy 3,000 ft2 (914 m2 ) of habitat. line between 1850 and 1950. Bulkheads,
This would result in a loss of 1,230 lb revetments, and groins have been used
(558 kg) of detritus per year. This in an attempt to retard or stop this
amount of detritus could support ap- shoreline loss, but they are often un-
proximately 9 lb (.4 kg) of shellfish per successful (Greer 1976). In addition,
year at 125 lb (57 kg) of shellfish sup- navigation channels are clog ged by
ported per acre per year (Carstea et eroded sediment and valuable real estate
al. 1975a, cited by Isard, W. 1972. Eco- is being lost (Greer 1976, U.S. Army
logic-Economic Analysis for Regional De- Engineer District, Norfolk 1977a). The
velopment. The Free Press, New York, constant and often severe erosion of the
New York). shoreline prevents permanent vegetation
It is possible to construct upland from becoming established. What already
bulkheads which preserve wetlands and is present is eventually washed away as
have a relatively minor effect on the the shoreline recedes (U.S. Ar E
coastal ecosystem. Each proposed bulk- neer District, Norfolk undated b . The
head must be evaluated, based on its result is a steady loss of shoreline wild-
potential for damage, in light of com- life habitat and constant turbidity caus-
ed by soil being continually washed into
munity existing at the proposed site. the waterway.
124

Biological impacts of construction thus, loss of wildlife habitat would be
and existence of groins, bulkheads, re- slowed (U.S. Army Engineer District,
vetments, and large breakwaters are Norfolk undated b). The effects on in-
discussed in those sections of this re- tertidal biota would depend, in part, on
port. Data at hand afford no indication the amount of sand deposited, and how
of the possible impacts of sandbag sill rapidly deposition occurred. Since ero-
placement, but some inferences may be sion and accretion are natural process-
made as to type and degree of probable es, many intertidal organisms can adapt
effects. to changing bottom levels. Fish should
be little affected except that reduced
Sandbags sills are long polyvinyl- tu rbidity mjght prove beneficial. With
chloride-coated nylon baos (Dura-bacs) no action, erosion might continue. The
filled with sand. Their dimensions are dredging for beach nourishment is a
13 ft (4 m) long, 5 ft (1.5 m) wide, biologically more harmful alternative, as
and 2 ft (0.6 m) high. They are plac- well as being costly.
ed in the intertidal zone, usually less
than 50 ft (15 m) channelward of the Additional information is being de-
mean high waterline. When filled, each veloped from. ongoing studies at Virginia
bag weighs 4 tons (3.6 metric tons), Institute of Marine Science concerning
which is more than waves in the bay sandbag sills in Chesapeake Say.
can move. Cost is reported as varying
from $50 to $150 depending on whether C A S E HISTORY - PIERS, P I L I N G S ,
professional help was obtained (Greer A N D 0 T H E R SUPPORT STRUCTURES
1976). IN COASTAL R E G 10 N 7 - N 0 R T H
ATLANTIC
No data on the construction effects
were found. Placing the sill breakwaters The literature contains very little
amounts to pumping them full of sand information on piers and pilings in the
and locating them parallel to the erod- Coastal Region 7. Carstea et al. (1975a)
ing shoreline. The area directly beneath present a theoretical case study of a
each bag would be lost as habitat and 200-ft (61-m) timber pier in the north-
the source of sand could cause some de- eastern U nited States. A developers'
pletion elsewhere. Without specific in- handbook which contains some informa-
formation on construction methods, no tion on this topic for Connecticut is
further impacts can be predicted. presented by Carroll (undated).

Once placed, sandbaq sills have The construction of a timber pile
shown themselves to be very effective pier is usually of short duration. For
in rebuilding beaches in the Chesapeake example, Carstea et al. (1975a) estimate
Bay. In one case a beach was doubled constrUction time of a 50-ft (15-m) long
in width in three weeks (Greer 1976). pier at 2 to 4 days, using trucks for 3
How this local accretion affects adjacent hr, a piledriver for I hr, and a crane
beaches is not stated. The U.S. Army for 10 hr. A slight increase in water
Engineer District, Norfolk (1977e, un- turbidity and sedimentation may result.
dated b), predicts no adverse effects Increased noise and air pollution levels
due to flood height and drift, reduction are usually not excessive.
of erosion, or accretion on beaches.
They also expect no adverse effects on This region is characterized by
water quality, water supply, or aesthet- numerous types of environments (Vir-
ics. Warning sions are recommended to ginia Institute of Marine Science 1976).
prevent boaters from hitting the sills, Consequently, impacts on the environ-
which are submerged at least during ment due to a specific type of structure
high tide. will vary from place to place. Effects of
a pier on areas such as wetlands, tidal
Prevention of the shoreline erosion flats, grassbeds, breeding n u rseries ,
should have beneficial effects on the wintering and feeding areas, and migra-
biological resources of the area. Upland tion pathways are the most significant
vegetation loss would be reduced and, ( C a rstea et al. 1975a). Productivity
125

will be decreased in the area under the Except for Long Island, little in-
pier. This can include vegetation, formation on jetties in the New England
algal, and shellfish productivity. Grass- area was found. The amount of biologi-
beds will also be affected by resultant cal data was minimal and was generally
boat traffic as will the fish activities. applicable to most of the United States
Carstea et al. (1975a) recommends that coastline (Carstea et al. 1@75a).
grass beds and other areas of signifi-
cant natural resource productivity be Fire Island Inlet on Long Island
avoided as sites for pier construction. has a documented history extending
back to 1825. Fire Island is a long bar-
Wooden structures in this area rie r beach lying off the south shore to
should be properly treated against ma- Long Island. It is broken by a number
rine wood borer attack, although the of inlets, many of which have been sta-
problem of attack against treated wood bilized by jetties. The Fire Island Inlet
piles should not be as extensive as in is unusual in that two sections of the
some of the warmer coastal waters to barrier beach, Fire Island and Oak
the south. The gribble (Limnoria tri- Beach, overlap and the inlet curves be-
punctata), considered to be e species tween them. An irregular channel is
causing the greatest threat to creosote maintained by strong tidal currents in
and coal tar treated piles, only breeds the inlet, but throughout its recorded
where the temperatures are above 57'F history the channel has maintained its
(14'C) and is, therefore, not prevalent S-shape. Over the years both erosion
in Coastal Region 7 (Lindgren 1974). and accretion has occurred so that Fire
Island has grown toward the west and
A single residential pier is not Oak Beach has been cut back (Shepard
likely to have an extensive impact on and Wanless 1971).
recreation in the general area. How-
ever, several piers in the area may re- A jetty was completed at Democrat
strict recreational activities and shore- Point in 1941. This temporarily stopped
line access. Pier size and number like- the westward advance of Fire Island.
wise affect socioeconomics of the area. The outer beach soon filled behind the
Piers used in connection with a launch- jetty on the south side of the island.
ing ramp or marina may cause increased Following this,sand was deposited land-
usage of the area and affect property ward of the north side and caused a
values or ecological relationships. bar to develop. The bar eventually
reached nearly across the inlet to Oak
The possible alternatives to a tim- Beach. As the channel narrowed, the
ber pier used for moorage in this area strength of the tidal currents increas-
would include solid-fill piers, anchor ed, and severe erosion occurred on Oak
buoys, single piles, dolphins, placement Beach. The beach was artificially nour-
of boats in local marinas, or land stor- ished and a new channel cut, but the
age. The use of anchor buoys or piles latter soon filled. A second jetty was
would cause less adverse impact to the built and erosion has apparently stop,
environment. The use of a solid-fill ped; however,an adequate channel does
pier would, in most cases, be an unsat- not exist through the inlet (Shepard
isfactory alternative due to the influ- and Wanless 1971).
ence it would have on water movement
and sediment transport. Jetties, as with other shoreline
structures which interrupt littoral drift,
A single, properly designed and upset the natural beach processes and
constructed open-pile pier would cause cause unwanted and sometimes unfore-
relatively little adverse impact to local seen erosion and accretion (Davis et al.
biota. Most of the impact would be as 1973). This is well illustrated by the
a result of related activities, such as changes in Fire Island Inlet. Not shown
dred gin g or increased usage of the were the effects of these changes on
area. the plants and animals of the area. No
information was given on habitat loss or
CASE HISTORY - JETTIES IN COASTAL alteration. It can be assumed that the
REGION 7 - NORTH ATLANTIC construction and existence of the jetties
126

caused impacts on the biological envi- protect the upland against wave dam-
ronment. Among the effects of jetty age. Bulkheads also provide mooring
construction at Fire Island Inlet, the facilities in many areas. Many unsatis-
following are easily predicted: turbid- factory methods of shoreline protection
ity, destruction of benthic organisms, may be employed prior to installation of
reduction of species diversity and food an adequate structure such as a bulk-
supply, release of toxic sediments, and head (U.S. Army Corps of Engineers
creation of new substrate (Carstea et u n dated
al. 1975a). The validity of these pre-
dictions could be questioned, however. Many possible construction alterna-
Additional study would be required to tives exist. They vary substantially in
discover site specific impacts. cost. A wire mesh, woodpile, or sand-
bag bulkhead may cost no more than
Jetties are designed to stabilize $15 per linear foot (0.3 m), while a
inlets and, according to Kieslich and steel bulkhead may cost as much as
Mason (1975), two objectives must be $330 per linear foot (0.3 m) (U.S.
considered. These are minimizing un- Army Corps of Engineers undated).
desirable effects of wave action on nav- Among the construction alternatives
igation channels and eliminating artifi- which may be considered in addition to
cial maintenance of the channels. These many types of bulkheads are revet-
objectives do not, in any way, consider ments, breakwaters, and groins.
biological impacts of the jetties. In fact,
no source of information was encounter- Construction impacts of bulkheads
ed which dealt with the physical or bio- are similar to those in other areas of
logical impacts of jetties. the country, including increased turbid-
ity and noise, reduced air quality, and
CASE HISTORY - BULKHEADS A N D smothering of some organisms in the
ASSOCIATED DREDGING IN COASTAL backfill area. Resuspension of bottom
REGION 8 - GREAT LAKES sediments will be greater when dredging
is associated with bulkhead construc-
In the Great Lakes region (Coastal tion. The use of diked disposal for
Region 8) there are a number of refer- hydraulic dredge spoils results in siq-
ences dealing with bulkheads, but very nific a ntly les s tu rbidity than many
few dealing with associated environmen- other methods of disposal (Morton
tal impacts. Boberschmidt et al. (1976) 1976).
discussed environmental impact of small
structures in the Chicago District of Bulkheads and seawalls are often
the U.S. Army Corps of Engineers. successful in providing immediate pro-
They provided an analysis of a hypo- tection for areas in which no further
thetical 200-ft (61-m) bulkhead on the bluff recession can be tolerated, but
Fox River in Wisconsin which involved they frequently fail because of toe ero-
no dredging.They also considered main- sion and back pressure (Michigan Sea
tenance dredging at a commercial dock Grant Advisory Program undated). For-
on the Illinois River. Morton (1976) ney and Lynde (1951) document a his-
has provided a comprehensive review of tory of attempts to protect the Presque
the ecological effects of dredging. The Isle peninsula from erosion.
U.S. Army Corps of Engineers (undat-
ed)gives an excellent layman's introduc- The effects of bulkheads on coastal
tion to shoreline protection structures processes are similar to those found in
for the Great Lakes. Because of a lack other coastal regions. Erosion in adja-
of specific information, only generaliza- cent areas which are not bulkheaded or
tions about the effects of bulkheads in otherwise protected can sometimes be
the Great Lakes are contained in this ex pected. Littoral transport may also
case history study. be affected. A lack of dissipation of
wave energy can be expected on the
Bulkheads are constructed in the lakeshore during storms as compared to
Coastal Region 8 to retain, or prevent the unbulkheaded beach (Boberschmidt
the sliding of, land and secondarily to et al. 1976).

127

Biological impacts resulting from Four Mile Park on the Lake Huron
the presence of a bulkhead include some shore in Sanilac County, Michigan, was
reduction in littoral zone productivity. chosen as a test site for the six qroin
Foreshore habitat is likely to be elimi- types (Table 3). The bottom is-clay
nated by construction of a bulkhead. derived from the high clay bluffs along
In rivers,bulkhead construction reduces the shore. Erosion has long been a
cover along the banks (Boberschmidt et problem and homes have been destroyed
al. 1976). Dredging may cause increases as the bluffs eroded (Brater et al.
in suspended solids, reduction in dis- 1974). All six groins have had some
solved oxygen and increased concentra- success in trapping sand at the base of
tion of hydrogen sulfide, and release of the bluffs (Figures 56 to 59); however,
pollutants which may be trapped in the the bluff is continuing to recede (Brat-
sediments (Morton 1976). These factors er et al. 1977).
can be detrimental to fish and other or-
ganisms in the vicinity of the dredging No information on construction im-
operation. pacts was given. However, they can be
assumed to vary from mild turbidity and
Bulkheading may protect certain beach disturbance for the sandbags to
areas from erosion, at least temporarily. somewhat more turbidity and beach dis-
Bulkheads may also provide mooring fac- turbance plus air and water pollution
ilities. However, recreational activities for-- rock mastic structure. These were
requiring unaltered habitat will be re- constructed by pushing the rocks pre-
stricted by bulkhead construction. viously dumped on the beach into place
with bladed tractors anO pouring hot
Because bulkheads may result in asphalt mastic over them (Brater et al.
an increased energy environment and 1974). The effects of construction activ-
erosion of adjacent beach areas, riprap ities on the biota is not known. Since
revetments may be preferred as an al- the shoreline was actively eroding, with
ternative. If the bulkhead is needed, little or no beach, any organisms pres-
riprap revetment may be placed in front ent should be adapted to a disturbed
.of the bulkhead to reduce scour and environment.
biological damages. Exchange of subsur-
face water is facilitated through riprap; The success of the groins in trap-
wave energy is somewhat reduced be- ping sand resulted in a change from a
cause of its increased roughness. Both clay to a sand substrate. This may
revetments and bulkheads may limit ac- have resulted in a change in species
cess to beaches. Groins and breakwa- composition of bottom dwelling organ-
ters can also be considered as alterna- isms. When a beach accumulates enough
tives to preserve a beach by altering sediment to prevent storm waves from
shoreline processes. striking the bluffs and continuing the
erosion, loss of upland vegetation and
CASE HISTORY - GROINS IN COASTAL man-made structures along the bluff
REGION 8 - GREAT LAKES should stop.

The Michigan Demonstration Ero-
sion Control Program is involved in an
ongoing research program to test the
effectiveness of various shore protection
devices. The physical environment at
each test site is known; but, unfortu-
nately, no information is collected con-
cerning the biological environment. The
other sources of information concerned
with groins in the Great Lakes do not
include biological impact data either.
Bioloqical effects must be inferred from
general information.

128

Table 3. Groin types and their performances,
Sanilac County, Michigan (Brater et al. 1974, 11075, 1@-77).

Groin Year Cost/ft Construction Performance Per7formance
type placed of groin problems evaluation 10,74 evaluation 1975

3 longard 1973 $ 55 Installation inter- Intact, no mainte- Intact, no mainte-
tubes, 40- rupted by storms, nance; sand nance; sand
in (102-cm) top tube not placed trapped but trapped but bluff
stacked bank receded still recedes

Longard tube, 1974 $ 71 None Intact, no mainte- Intact, no mainte-
69-in (175-cm) nance, some bank nance; sand
recession, no trapped and only
more successful minor bluff
than 40-in recession
DO
(102-cm) tubes

Sandbaos 1973 $109 None Sand bags lost, Not durable but
torn; sand offers good tem-
trapped porary protection

Rock mastic 1973 $ 111:14 Difficulty obtain- Intact, no mainte- Minor damage, no
ing proper rock nance; sand maintenance; not
trapped attractive

Gabion 1974 $ 3C None stated Too early to
evaluate

Tirnber crib 10.75 $ 30 Difficulties aet- Not installed Too early to
tinc it buift evaluate

`z -14 '40
-00 "0'

LIT

--irk

9w
Figure 56. A 40-in (1-m) Longard tube groin at Sanilac site, Photograph
courtesy Michigan Department of Natural Resources.

6@ @@A

- - - - - - - - - -

Figure 57 Sandbag groin at Sanilac site, showing loss of sandbags at
lake end. Photography courtesy of Michigan Department of Natural Resources.

Figure 58. Gabion groin at Sanilac site. Photograph courtesy of Michigan
Department of Natural Resources.

"4 Ak.,-

Na,

INA
4@

7*
A

X i
NS,
L '6@11
A Ak,
,Figure 59. Rock mastic groin at Sanilac site. Photograph courtesy of
Michigan Department of Natural Resources.

RESEARCH IN PROGRESS
Seven research projects investigat- Byrne and Gary Anderson of Virginia
ing the design of and/or biology associ- Institute of Marine Science are working
ated with shoreline structures are cur- with sills to stop erosion in Chesapeake
rently underway. Generally these pro- B ay. The sills are installed offshore in
jects can be placed in three categories: shallow water.They have used the poly-
vinylchloride-coated nylon Dura-bags
0 Those looking for low-cost shore- filled with sand to construct sills to
line protection measures for use by cause nearshore accretion. The cost for
the 'property owner; each sill was approximately $12.50 per
linear foot (0.3 meter) installed. Pre-
0 State of the art reviews of the liminary results indicate this method of
structure type and/or its effect on erosion co ntrol is very effective in
the environment; parts of Chesapeake Bay.
0 Research about the effects of a Dr. Paul Shuldiner of the Univer-
structure type on either the bio- sity of Massachusetts at Amherst is
logical or p hysical environment. hea din g an investigation of the impact
of highways on wetlands. T his study
Projects investigating various low- is beina conducted for the National Co-
cost protection measures, such as the operative Highway Research Council.
Michigan Demonstration Erosion Control The expected products will be an an-
Program, often include construction of a notated bibliography, a state of the art
structure as well as identification of the review, and six case studies. It began
problems. The other two types of re- in mid-1977 and was expected to be
search usually concentrate on effects of completed by mid-1978.
existing shoreline structures. William Brisby of Moorpark College
The Michigan Demonstration Ero- (Moorpark, California) reports that a
sio n Control Program, initially funded consulting firm is doing a study on the
by the Michigan Department of Natural biota of Rincon Island, California, for
Resources, began in 1973. Since that the U.S. Army Corps of Engineers.
time, it has received funding from the Rincon Island is man-made, located ap-
several @other organizations, including proximately 0.5 mi (0.8 km) offshore.
the Michigan Sea Grant Program. The A causeway runs to the island from
objective of this program was to find shore.
low-cost methods of protecting Michi- J.M. Kieslich and C. Mason (1976)
gan's shoreline which a property owner of the U.S. Army Corps of Engineers
could help construct. Low cost was de- are working on the channel entrance
fined as under $100 (preferably less response to jetty construction. In their
than $50) per square foot of protection. 1975 paper, they generally concluded
Nineteen shore protection demonstration that wave processes contribute more to
installations have been constructed. channel migration near a jetty. than hy-
These include revetments, breakwaters, draulic processes do. Additional work
bulkheads, and groins. Laboratory in- is being performed by them to quantify
vestigations and historical stu dies of the controlling wave and hydraulic pro-
erosion conditions are also being con- cesses. Their results will be presented
structed. It is hoped that by 1978 in a future report.
enough information will be available to
evaluate the effectiveness of each in- Two studies are underway at the
stallation. A detailed engineering-eco- University of Rhode Island at Narragan-
nomic evaluation of the structures will sett. Neil Ross and Gail Chmurg are
be made. Reports are published each conducting a state of the art review of
year discussing data collected during the biological impacts of small boat har-
the previous year. bors. Daniel O'Neil is investigating the
Greer (1976) reported that Robert fouling communities on the floating tire
134

break w ate rs for the Marine Advisory Researcher Structures to
Service. The objectives of O'Neil's be StuTed
stu dy are to i d e ntify and q ua ntify
fouling communities, determine rates of Cole undated breakwater,
growth, look for the biological mechan- harbor
isms of controlling fouling communities,
and study water circulation in small The only results of these proposed
harbors. The study was to be completed studies which were uncovered during
by Fall 1977. the present study are contained in the
articles by Brater et al. (1974, 1975,
Some articles contained in the lit- 1977). These studies were alluded to
erature make reference to studies which in the Marks and Clinton (1974) article.
were planned or underway at the time
of publication of those articles. R efer- It is presumed that there are many
ences published prior to 1975 which in- relevant studies underway that are not
dicated that research was planned or noted in the literature or that were not
underway included determined during interviews or in re-
sponses to questionnaires. In addition,
Researcher Structures to there are most likely numerous studies
be Studied underway that deal with strictly engi-
neering aspects of shoreline structures.
Georgia Depart groin The best sources of information regard-
ment of Natural ing ongoing studies are probably the
Resources 1974 U.S. Army Engineer Coastal Engineer-
ing Research Center in Fort Belvoir,
Marks and Clinton revetments, Virginia, and the U.S. Army Engineer
1974 breakwaters, Waterways Experiment Station in Vicks-
bulkheads, burg, Mississippi.
and groins A large number of studies which
Machemehl and Abad groin are somewhat peripheral to the present
1973 study are also presently underway. Ex-
amples would be the numerous biological
Stone et al. 1973 reef studies on artificial reefs and dredging
effects and engineering studies on mate-
Berg and Watts groin rials, life expectancy, and structure
1971 design.
Riese 1971 groin ENVIRONMENTAL IMPACT ASSESSMENT
METHODOLOGY
Cronin et al. dredge-fill, The majority of studies assessing
1969 jetty, groin the environmental impact of minor shore-
Colley 1967 pilings line structures on the coastal environ-
ment have been nonexperimental. 0 ver
Slaughter 1967 bulkhead 75% of the information sources reviewed
were literature reviews, guidelines, and
Saville et al. 1965 revetment nonexperimental environmental impact
assessments and statements.
Lee 1964 harbors Systematic research studies con-
Scott 1964 jetty ducted before and after the structure
installation were rare, and those con-
Nagai 1961 breakwater ducted were almost exclusively concern-
ed with physical effects or engineering
Brater 1954 bulkhead, considerations. One ongoing research
revetment, program that falls into this category is
groin Michigan Demonstration Erosion Control
135

Program (Brater et al.1974, 1975, 1977;
Marks and Clinton 1974). This study is
limited primarily to physical effective-
ness of low cost groins and revetments.
In another study, historical records
were compared with the existing condi-
tions to discover changes in littoral
drift and the beach erosion after a jetty
was constructed (Dantin et al. 1974).
One series of biological studies was con-
ducted both prior to and after installa-
tion of various parts of a marina in
southern California (e.g., Reish 1961,
1962, 1963).

Another research method involves
systematic studies conducted after the
installation of structures. These studies
primarily described the physical condi-
tions in the presence of a structure.
For instance, Diskin et al. (1970) de-
scribed piling up of water behind low
and submerged breakwaters, and Nagai
(1961) discussed the absorption of wave
energy by concrete facing copponents.
An exception to this generalization has
been a number of biological studies
which have compared the existing bulk-
headed areas to adjacent natural shore-
lines. Examples of this method of study
are found in Corliss and Trent (1971),
Ellifrit et al. (1972), Heiser and Finn
(1970), Millikan et al. (1974), Mock
(1966), Moore and Trent (1971), Trent
et al. (1976), and White (1975).

136

EVALUATION OF EXISTING DATA

INFORMATION OBTAINED B uoys and floatin g platforms
Piers, pilings, and other sup-
555 references were obtained that port structures
were considered potentially applicable to
the objectives of the study. N u merous Based on this classification and the
additional articles were uncovered, but histograms in Figure 60, bridges and
not obtained because they were not ap- causeways, and the small boat harbors
plicable. The 555 articles were consid- would appear to have received a small
ered as potentially applicable, based on amount of study in light of their poten-
their title or on recommendations con- tial impacts. It should be noted, how-
tained in the questionnaires or acquired ever, that the data base contains much
during interviews. These articles were information that is not impact assess-
read and abstracted, and data sheets ment oriented, but directed at engineer-
prepared where appropriate. An article ing constraints.
was assigned a rating only if it was di-
rectly applicable to the present study. Figure 61 contains the number of
About 405 of the articles that were read references obtained by structure type
were considered directly applicable. and coastal region. The general cate-
The remaining 150 articles contained in- gory is for articles that were not spec-
formation that was related, but not di- ific for one coastal region. Much of the
rectly applicable to the study. acq uired information was not region
s pecific. In many cases the histograms
Figure 60 contains histograms of reflect structure prevalence and history
the number of references obtained by of associated difficulties within that re-
structure, category, and rating. It is gion. Examples would be jetties in the
emphasized that the rating was for use- North Pacific (Coastal Region 1) and
fulness to the present study and not bridges and causeways in South Florida
scientific excellence or validity. I nfor- (Coastal Region 4). This is not always
mation of questionable validity is of the case, however, as is exemplified by
questionable usefulness, but information the small boat harbors in South Florida
of high veracity may also be of limited (Coastal Region 4).
usefulness.

The consensus of personnel who
worked on this study was that struc-
tures could be classified as having the
high, moderate, or low potential for
environmental impact as follows:

High impact potential

Small boat harbors
Bridges and causeways
B ulkheads
Breakwaters
Jetties

Moderate impact potential

Revetments
G roins
Ramps

Low impact potential

137

25-

20-

15-

10-

IA 5-

Qj
a) Al.
I+-
4) 1 2 ' 3 4 5 1 2 1 3 1 4 1 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 1 5
ck@ Breakwaters Bridge/Causeway Bulkheads Groins Harbor
4-
25-
00

:3 20-
M

15- U

10-

0 1 7-
1 2 3 1 4 1 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 3 4
Jetty Pier-Piling Buoys/Floating Revetments Rami)s
Platforms

Figure 60. The number of references by structure category and rating that contained information
to
ism

relevant to the present study. A rating of 1 indicated the articles that were most useful.

50-

45-

40-

36-

30-

25-

20-

15-

10-
If
5-

0 H General erall CHI CHICRI CHI(HICRIC RGe,,eral CH RICRICHIC rAIrPIr,,, WA CA rA General
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 7 3 4 5 6 7 8 1 2 3 4 5 6 7 8
4..
W Breakwaters Bridge/Causeway Bulkheads Groins Harbor

50- - - - -

S_
45- - - - -

40@ - - - -

35- - - - -

30- - - - -

25- - -

20- - -

15- - -

10-

5
I R ACIC C. IR C11 JUICH Gne, IR I H VCH CR I H C'.

0 MMI CRF 9CRI ICRTR General
C Hoc ".C R 'CIMRI C" H, C R C Reral C R C R 4 R! fI CH a wal CRICHICHICRICRICRICOCRITMen al -CRICRICHICHICRICHIC11CRGun ral CRICH CR 7 8
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 6 1 2 3 4 5 6
Jetty Pier-Piling Buoys/Floating Pl*atforms Revetments Ramps

Figure 61. The number of references by coastal region and structure that contained information that was
relevant to the present study. The general category is for references that were not specific to one region.

GENERAL COMMENTS ON THE DATA BASE

After evaluation of the existing these impacts are probably minor. T his
data base, several generalizations can syndrome seems to be more prevalent
be made as constructive criticism. for structures with low potential impact.

Much of the available information The o p p osite syndrome is also
was developed for a specific project as evidenced in the literature. An example
support fo r an environmental impact would be concluding no potential impact
assessment. Some of this information is based on a nonexistent data base.
biased in one direction or the other.
Much of the literature is negative
A large amount of the information in natu re. There are wany examples
on the effects of shoreline structures is where structures have had an overall
e ngineeri n g -oriented. There is also a positive impact on an area. Attraction
large body of literature concerning the of fishes to structures is often inter-
distribution and tolerance limits of biota preted as bein g a beneficial impact.
of the coastal zone. Very little informa- B oth p ositi ve and negative aspects
tion exists on the impact of structures should be evaluated.
upon the biota. As a result, most envi-
ronmental impact assessments rely on Much of the literature evaluates a
the ability of individuals to extrapolate structure as if it were in a vacuum.
impacts from what they know of the con- The impact of a single groin will often
struction . procedures, coastal physical be negligible, but that single groin may
processes, and nonstructure related bio- cause a stepwise series of groins to be
looical data. Most of these assessments built, each of which is to mitigate the
are made in a climate of potential litiga- effects of the previous groin. The
tion. The result is an extremely water- socioimpacts caused by bulkheads and
ed-down product that is only marginally the resultant house, or ramps and the
based on fact. The literature on bio- associated boating pressure are other
logical impacts of the minor shoreline examples. Factors such as these should
structures is characterized by these be considered when evaluating the im-
types of assessments. pact of structures.

An evaluation of the potential im-
pact of some minor shoreline structures
by a competent biologist often would re-
sult in a negligible impact conclusion.
U nfortu nately, the present regulatory
climate necessitates a lenothy discussion
of potential impacts. In order to pre-
pare such a discussion, seemingly in-
consequential matters are discussed at
such length that everyone starts believ-
ing they are truly problems. Lengthy
discourses of turbidity and sedimenta-
tion effects of rocks landing on a sand
bottom fill the impact assessment litera-
ture. It is doubtful that competent biol-
ogists would project a probable impact
due to fish gills being clogged, fish dy-
ing fram released toxic materials, ben-
thic organisms bein g smothered, and
primary productivity being reduced sim-
ply by the placement of stone in inter-
tidal habitats. However, these state-
ments are rampant throughout the liter-
ature, with the sideline comment that

140

RESEARCH NEEDS

A detailed review of the literature only when it was specific for a particu-
results in the conclusion that the data lar type of structure and a physical,
base available for projecting biological chemical, or biological environmental im-
impacts of minor shoreline structures is pact. Information from the other two
extremely sparse. The research needs data bases was not entered into the
are virtually unlimited for each type of system. During the present study, de-
structure and for each coastal region. scriptions of certain impacts recurred
It would be unreasonable to propose a through the literature. Examples of the
stu dy on each structure type within more significant recurrent impacts are
each coastal region that was designed to
determine the magnitude of each con- 0 Changes shoreline dynamics
ceivable type of impact. We have, there- 0 Affects littoral transport
fo re, proposed avenues of approach 0 Changes wave energy
that will result in timely and cost-effec- 0 Changes sediment composition
tive answers to the questions most fre- 0 Increases turbidity
quently asked. 0 Causes suspension of toxic
chemicals
Data used in determining biological 0 Changes dissolved oxygen,
impacts of the shoreline structures are salinity, or temperature
usually drawn from three data bases. 0 Shades the water
The most applicable data base is the 0 Affects circulation
one containing information on the chem- 0 Alters existing habitat or
ical, biological, or physical impact of a creates new habitat
specific type of structure. Examples 0 Alters species composition
would be articles on chemical releases 0 Affects migration patterns
from resuspended sediments during the 0 Socioeconomic changes due to
jetty construction, fis h attraction to increased area usage
breakwaters, and changes in beach pro-
file due to groins. As is evident in the
text of this report, this type of infor- A study should be per-formed to
mation is scarce. analyze each of the recurrent types of
impacts based on each of the three data
The second data base contains in- bases. For example, the effects of in-
formation on engineering considerations creased turbidity due to any of the
in structure design. Examples would structures would be a valuable study.
be methodologies for calculating wave An impact approach in addition to a
impact, structural integrity, or changes structural approach would result in a
in littoral transport. This information considerable refinement of the conclu-
is often useful in determining biological sions reached in this report.
impact, but is not directly applicable.
Review of available literature un-
The third data base contains infor- covered certain major gaps in the data
mation on biological phenomena that is base. The following recommended stud-
not related to a specific type of struc- ies would help to fill in some of these
ture. Examples of this type of informa- areas where information is lacking.
tion are the attraction of the fishes to
a rtificial reefs and other submerged 0 How are biological communities af-
structures; dredging effects upon ben- fected by structures which stabi-
thos; and succession, diversity, pro- lize shorelines?
ductivity, and biomass of the commun-
ities that foul submerged structures. 0 How do changes in wave energy
This information is useful if it can be patterns affect biological commun-
applied to a specific type of structure. ities ? For example, what are the
differences in communities in front
During the present study, infor- of and behind breakwaters?
mation was entered into the data base

141

0 What are the positive and negative habitat than a bulkhead or con-
effects of chancing the type of crete revetment?
habitat that occurs in the area
(e.g., rock vs sand)? 0 What are the cumulative effects of
0 Does construction-generated tur- many of the same type of struc-
bidit clog fishes' gills or zoo- ture in an area or a combination
y of many types of structures in an
plan kton/filtration mechanisms. Do area? Studies similar to those on
avoidance mechanisms operate to bulkheadinc! in Texas (Coastal Re-
prevent this? gion 3) are needed in the other
coastal regions and about other
0 Can loss of phytoplankton or mac- types of structures.
rophyte primary productivity due
to structure shading constitute a 0 What are the effects of shoreline
threat to an ecosystem? structures on waterfowl and other
0 Can loss of phytoplankton or mac- wildlife?
rophyte primary productivity due Answers to all the above questions
to construction turbidity constitute could be generated through field or lab-
a threat to an ecosystem? oratory studies. There are certain ques-
0 What are the effects of structures tions, however, that could best be an-
swered through a literature review
that protrude into the water or which incorporates all three of the
channelize current upon the migra- aforementioned data bases. The res ults
tion of fishes, mammals, and crus- of the literature review could answer
taceans? the questions or could serve as a firm
0 How do solid structures affect sys- basis on which to design the required
tems through alteration of circula- field or laboratory studies.
tion? The case history studies for each
coastal region were selected based on
0 What are the biological effects of the recommendations of local U.S. Fish
structures such as rubble mound and Wildlife Service personnel. T heir
groins or ri p ra p revetments i n recommendations were based on the most
areas where this type of habitat troublesome structures they encounter
did not formerly exist? when reviewing Corps of Engineers'
permit applications. In several cases,
0 Under natural conditions, is avail- there was not enough information avail-
able habitat one of the most impor- able to write a case history, and theo-
tant factors controlling the produc- retical case histories were constructed.
tivity of a specific organism? In other instances, the data base was
so poor that the majority of the case
0 What are the effects of altered histories was theoretical. Circumstances
wave energy patterns upon sedi- where theoretical information was used
ment c o w, p ositio n and associated would seem to be appropriate topics for
biological productivity? detailed study. These topics were

0 What are the zones of influence of
wave energy altering structures? Southern California
For example, how far away from a Coastal Region 2
bulkhead are the energy altera- Bulkheads
tio ns felt? B otto m profile and
sediment com positio n alterations South Atlantic
are included in this concern. Coastal Region 5
0 What are the effects of various Groins
types of submerged surfaces on South Atlantic
productivity? For example, does Coastal Region 5
a riprap revetment offer a better B ulkheads
142

North Atlantic In summary, there are numerous
Coastal Region 7 studies that would enhance the state of
Piers , piling, and other support the art relative to the prediction of the
structures biological impacts of minor shoreline
structures on the coastal environment.
North Atlantic One avenue of approach that will result
Coastal Region 7 in timely and cost-effective answers to
Jetties many structure-related questions is the
integration of the p u rely biological,
G reat Lakes purely engineering, and structure im-
Coastal Region 8 pact related data bases currently in
Bulkheads and associated existence. In addition to this approach,
dredging there are several field studies which, if
u n de rta ke n, would contribute substan-
Great Lakes tially to the presently available data
Coastal Region 8 base.
Groins (biological)

It was the consensus of prcdect
personnel that small boat harbors had a
high potential for environmental impact.
Small boat harbors can contain all of
the other structures mentioned in this
report. Harbors would, therefore, make
good case studies within each region of
the United States. The effects of num-
erous structures could be stu died at
one location and within the budgetary
constraints of one study. Sites will
have to be carefully chosen, however,
to assure that the effects of one struc-
ture type are not overpowering the ef-
fects of another or that secondary ef-
fects, such as petrochemical pollution,
are not of far greater significance than
the strictly structural effects.

Project personnel also considered
bridges and causeways to have a high
potential for environmental impact. Un-
like many other structures, their effect
can extend over an area much larger
than the immediate vicinity where they
are constructed. Such regional impacts
are discussed in the case history stud-
ies on bridges and causeways in Florida
(Coastal Regions 3 and 4). 0 etail e d
studies on the effects of bridges and
causeways would help to determine if
fears, arising largely from conjecture,
are factually based. It would be very
helpful if several locations could be
studied both before and after construc-
tio n. The effects on tidal circulation,
biological productivity, and flood con-
trol should be prime concerns of the
stu dy.

143

GLOSSARYI

Aerobic
Life processes occurring only in the presence of free oxygen.

Anaerobic
Life processes occurring without the presence of free oxygen.

Anadromous
Fish that reproduce in fresh water, but spend a portion of their life in
salt water.

Backfill
Material used to fill behind a small structure such as a seawall or bulkhead.

Backshore
Zone of beach lying between foreshore and coastline acted upon by waves
only during severe storms.

Barrier beach (also barrier island)
Bar essentially parallel to shore, with crest above normal high water.

Bay
Recess in shore or inlet between two capes or headlands; larger than cove,
smaller than gulf.

Baymouth bar
Bar across the mouth of an embayment.

Benthos
Organisms growing on or associated principally with the water bottom.

Berm
Nearly horizontal part of beach or backshore formed of material deposited
by wave action.

Biota
Animal and plant life of a region.

Biotic
Environmental factors which are the result of living organisms and their
activities.

Bluff
High steep bank or cliff.

Boat basin
Naturally or artifically enclosed or nearly enclosed harbor area for small
craft; see harbor.

Portions of this glossary have been estracted or adapted from Allen (1972) and
Hurme (1974).

144

Boulder
Rounded rock more than 10 in (25.4 cm) diameter; larger than cobblestone.

Breaker zone
Zone of shoreline where waves break.

Breakwater
Structure protecting shore area, harbor, anchorage, or basin from waves;
see jetty.

Bridge
Structure erected to span natural or artificial obstacles such as rivers,
highways, or railroads and supporting a footpath or roadway for pedestrian,
highway, or railroad traffic. A bridge would normally consist of structural
members made of steel, concrete, or wood.

Bridge abutment
Structure supporting the bridge at the point where the land meets the
water as distinguished from a pier which is wholly in the water.

Bridge pier
Structure in the water which supports a bridge.

Bulkhead
Structure or partition built to prevent sliding of the land behind it. It
is normally vertical or consists of a series of vertical sections stepped
back from the water. A bulkhead is ordinarily built parallel or nearly
parallel to the shoreline.

Buoy
A floating object moored to the bottom of a waterway, used for marking,
moorage, etc.

Caisson
A watertight structure used for construction work in water.

Calcareous
Consisting of or containing calcium carbonate.

Canal
Artificial watercourse cut through land area.

Cape
Relatively extensive land area jutting seaward from continent or large
island which prominently marks change or interruption of coastal trend.

Causeway
A way of access, or raised road, typically across marshland or water.
A causeway would normally consist of an embankment constructed of earth,
sand or rock dredged or dumped in place.

Cliff
High steep face of rock.

145

Climax
Final and most stable of series of communities in succession, remaininq
relatively unchanged as long as climatic and physiographic factors remain
constant.

Cobble
Naturally rounded rock, 3 to 10in diameter.

Cofferdam
A temporary watertight structure built in the water and pumped dry for
construction of piers, bridges, dams, etc.

Community
Association of plants and/or animals in given area or region in which
various species are more or less dependent upon each other.

Coquina
A soft porous limestone with high shell and coral content.

Cove
Small, sheltered recess in coast, often inside larger embayment.

Cumulativd effects
Effects which result from an accumulation of a number of structures in
a coastal area.

Current, long shore
Littoral current in the breaker zone moving parallel to the shore.

Deadman
A wooden pile, concrete block or horizontal timber placed landward of a
bulkhead and used to anchor the structure; (see Figure 27).

Delta
Alluvial deposit, triangular or digitate, formed at river mouth.

Design wave height
Wave which is used for designing coastal structures such as revetments,
breakwaters, jetties, or groins. The wave height and period assists the
designer in selecting sizes of armor units and other features of the
structure. The design wave will probably not be the maximum wave for
economic reasons.

Detached breakwaters
Breakwaters standing free of the shore; see breakwater.

Dike
Wall or mound built around low-lying area to control flooding.

Disclimax
Plant community in which species composition is maintained by continuing
disturbance.

146

Dock
Place for loading and unloading of vessels/for small boats; see pier.

Dolos, dolosses (plural)
A type of precast concrete armor unit used for facing rubble mound
structures.

Dolphin
Cluster of piles; see piling , also Figure 43.

Dredge
To deepen by removi no substrate materi al ; al so, mechani cal or hydraul ic
equipment used for excavation.

Ebb tide
Period between high water and the succeeding low water; falling tide.

EIA
Environmental impact assessment (or analysis); the analysis of the poten-
tial impact of a proposed development project upon its immediate and more
distant environment.

EIS
Environmental impact statement; the actual presentation that results
from the EIA.

Embankment
Artificial bank such as a mound or dike, generally built to hold back
water or to carry a roadway.

Embayment
Indentation in shoreline forming open bay.

Endemic
Peculiar to particular region or locality; native.

Erosion
Wearing away of land by natural forces; e.g., by wave action, tidal cur-
rents, littoral currents, deflation.

Estuary
Region near river mouth where fresh river water mixes with salt water of
sea.

Fetch
The distance over unobstructed open water on which waves are generated by
a wind having a constant direction and speed.

Filter
Transitional layer of gravel, small stone, or fabric between fine material
of an embankment and revetment armor.

147

Float
Floating platform or other device moored to bottom of a waterway.

Flood tide
Period between low water and the succeeding high water; rising tide.

Food chain
Dependence of a series of organisms, one upon another, for food; begins
with plants and ends with largest carnivores.

Forb
Herb other than grass.

Foreshore
Part of the shore lying between crest of seaward berrr. and ordinary low
water mark.

Freeboard
Distance between waterline and top deck of a structure or vessel.

Fringe marsh
A narrow wetland at the edge of a body of water.

Gabion
Hollow cylinder filled with earth; see revetment.

Grass 2ats
FPat areas alternately covered and uncovered by tidal action which sup-
port extensive growths of grasslike vegetation.

Gravel
Loose, rounded fragments of rock, 0.75 to 3in (1.8 to 7.6cm) diameter.

Groin., g@-oUne (Bristish)
A rigid structure built at an angle (usually perpendicular) frorr, the shore
to protect it from erosion or to trap sand. A groin may be further defined
as permeable or impermeable depending on whether or not it is designed to
pass sand through it.

Groin field (also groin system)
Series of groins spaced along the shoreline acting together to protect a
section of beach.

Gribbles
Small marine isopod crustacean (Limnoria spp.) that destroys submerged
timber.

Gulf
Large embayment, entrance generally wider than length.

Habit
Characteristic mode of growth or appearance.

148

Habitat
Interacting physical and biological factors which provide at least minimal
conditions for one organism to live or for a group of organisms to occur
together.

Habitat type
All the area that presently supports a community or organisms.

Harbor
Any protected water area affording place of safety for vessels; for the
purposes of this study, includes boat basins, marinas, and moorage.

Headland
High steep-faced promontory extending into sea.

Herb
Seed-producing vascular plant that produces no woody tissue and dies back
at end of growing season.

Hook
Spit or narrow cape of sand or gravel which turns landward at outer end.

Impact
An action producing a significant causal effect or the whole or part of a
given phenomenon.

Impermeable groin
Groin through which sand cannot pass; see groin.

Individual lot pier
One-owner pier usually serving single property.

Inlet
Water passage to an inland water; or a recess in the shore such as a bay.

Internation Great Lakes tidal datum (IGLD)
See tidal datum.

Invertebrate
Animal lacking an internal skeletal structure, e.g., insects, mollusks,
crayfish, etc.

Isthmus
Narrow strip of land, bordered on both sides- by water, connecting two
larger bodies of land.

Jet
To place in ground by means of jet of water acting at lower end.

Jetty
Structure extending into body of water designed to prevent shoaling of
channel by littoral materials and to direct or confine stream or tidal
flow; see breakwater.

149

Key (also cay)
Low insular bank of sand, coral, etc.

Lagoon
Shallow body of water, usually connected to sea.

Levee
Usually manmade dike or embankment to protect land from inundation.

Life cycle (life stage)
The various phases or changes through which an individual passes in
its development from the fertilized egg to the mature organism.

Lightering buoy
Point buoy; tie up for a small craft; see buoys and floats.

Littoral
Of or pertaining to a shore.

Littoral drift
Sedimentary material in littoral zone under influence of waves and cur-
rents.

Littoral transport
Movement of littoral drift by waves and currents; includes movement par-
allel to and perpendicular to shore.

Marina
Small harbor or boat basin providing dockage, supplies, and services for
small pleasure craft, see harbor.

Marine way (also marine railway, Zaunchway)
Railway extending into water used to launch or to pull vessels from
water; see ramp.

Mean high water
Average height of high waters over a 19-yr period (MHW).

Mean low water
Average height of low waters over a 19-yr period (MIHI-J).

Mean sea level
Average height of surface of sea for all stages of tide over 19-yr period
(MISL).

Mean tide level
Plane midway between mean high water and mean low water (also half-tide
level).

Migration
Mass moverrent of animals to and from feeding, reproduction, or nesting
areas.

150

Mole
Massive land-connected, solid-fill structure of earth (generally revetted)
masonry or large stone; see jetty.

Monolithic
Type of construction in which structure's component parts are bound to-
gether to act as one.

Moorage
Place to make a vessel fast with anchors, cables, etc.; see harbor.

Mud
Fluid-to-plastic mixture of finely divided particles of solid material
and water.

Mud flats
Low, unvegetated mud substrate that is flooded at high tide and uncovered
at low tide.

Neap tide
Tide occurring near time of quadrature of moon with sun, usually with
range 10% to 30% less than mean tidal range.

Nekton
Macroscopic organisms swimming actively in water; e.g., fish.

Neritic zone
Relatively shallow water zone which extends from the hich-tide mark to
edge of continental shelf.

Nesting
Pertaining to brooding eggs or rearing young.

Nourishment
Process of replenishing a beach; naturally by longshore transport or
artificially by deposition of dredged material.

Nursery
Area where young are born or cared for.

Nutrients
Elements or compounds essential as raw material for organism growth and
development; e.g., carbon, phosphorous, oxygen, nitrogen.

Outfall
Structure extending into a body of water for the purpose of discharging
an effluent (sewage, storm runoff, cooling water).

Parapet
Low wall built along edge of a structure.

151

Pass
Navigable channel through bar, reef, shoal, or between adjacent
islands.

PeZa c zone
96pen sea, away from the shore.

Periph ton
Aitached microscopic organisms growing on the bottom or on other sub-
merged substrates.

PermeabZq grq-bn
Groin with openings large enough to permit passage of appreciable quan-
tities of littoral drift; see groin.

PhytoFZankton
lanktonic plant life.

Pier
A structure, usually of open construction, extending into the water from
the shore. It serves as a landing and mooring place for vessels or for
recreational uses. Includes trestles, platforms, and docks.

Pile
Long, heavy timber or section of concrete or metal driven or jetted into
earth or seabed for support or protection.

Pile cluster
Dolphin; group of adjacent piles.

Pile dike
Dike construction of piles.

PiZe_, sheet
Pile with generally slender flat cross section, meshed or interlocked
with like members to form wall or bulkhead.
PilinKroup of piles.

Pioneer species
One capable of establishing itself in a barren area.

Plankton
Suspended microorganisms with relatively little power of locomotion that
drift in water and are and are subject to action of waves or currents.

Point
Outer edge of any land area protruding into water, less prominent than
cape.

152

Point buoy
Mooring buoy, usually for single vessel; see buoys and floats.

Port
Place where vessels may discharge or receive cargo.

Productivity
Rate of production of offspring, or fixation of solar energy.

Quay
Stretch of paved bank or solid artificial landing place parallel to
navicable waterway used as loading area.
Ramp A uniformly sloping platform, walkway, or driveway. The ramp commonly
seen in the coastal environment is the launching ramp which is a sloping
platform for launching small craft.

Reef
An offshore chain or ridge of rock or ridge of sand at or near the sur-
face of the water. An artificial reef is a similar chain or ridge built
up by man to resemble a natural reef.

Retaining wall
Wall built to keep bank of earth from sliding or water from flooding;
see bulkhead.

Revetment
A sloped facing built to protect existing land or newly created embank-
ments against erosion by wave action, currents, or weather. Revetments
are usually placed parallel to the natural shoreline.

Ria
Long, narrow inlet with depth gradually diminishing inward.

Riprap
Layer, facing, or protective mound of stones randomly placed to prevent
erosion, scour, or sloughing of structure or embankment; see revetment.

River datum
Reference plane for river; each river has a characteristic datum.

Roadstead (also road)
A place less enclosed than a harbor where ships may ride at anchor.

Rubble
Rough, irregular fragments of broken rock.

Rubble-mound structure
Mound of random-shaped and randorr-p-I aced stones protected with cover
layer of stones or specially shaped concrete amor units.

153

Sand
Rock fraoments less than 0.75in (1.9cm) diameter.

Scouring effect
Removal of underwater material by waves and currents, especially at base
or toe of a structure.

SeawaZI
Structure separating land and water areas, primarily designed to protect
land from wave action; see

Sedimentation
Process of deposition of material, usually soil or organic detritus, in
the bottom of a liquid.

Sessile
Attached to substrate and not free to move about.

ShingZe
Any beach material coarser than ordinary gravel, especially with flat or
roundish pebbles.

ShoreZine, eroding
Shoreline which, by wave action, longshore current, or frequent storm
activity is losing material.

SM., sandbag
A small breakwater used for shore protection which is constructed from
sand filled nylon tubes. Sandbag sills are usually placed parallel to
the shoreline and just below the intertidal zone.

Sizt
Loose sedimentary materials with rock particles less than 0.05 mm
diameter.

Szip
Berthing space between two piers.

SpandreZ (bridge)
A bridge with a series of arches supporting the roadway.

Spawning
Production and deposition of eggs, with reference to aquatic animals.

spit
Small point of land or narrow shoal projecting into body of water from
shore.

Spring tide
Occurs at or near time of new or full moon and rises hichest and falls
lowest from mean sea level.

154

Stone, derrick
Stone heavy enough to require mechanical means of handling individual
pieces, generally 1 ton (0.91 metric ton) and over.

Storm tide
Rise above normal water level on open coast due to action of wind stress
on water surface.

Structure support
Pilinas or other structures with principal function being the support
of a structure which extends over the water.

Substrate
Solid material upon which an organism lives or to which it is attached.

Succession
Sequence of communities which replace one another in a given area.

Taxon (pl taxa)
Any taxonomic unit or category of organism; e.g., species, genus, family,
order, etc.

Terrestrial
Growing or living on or peculiar to the land, as opposed to the aquatic
environment.

Terrigenous
Relating to oceanic sediment derived directly from destruction of rocks
on earth's surface.

Tetrapod
A type of precast concrete armor unit with four leas used for facing
rubble-mound structures.

Tidal datum
Plane or level to which elevations or tide heights are referenced.
These vary for different coastal regions.

Tidal flat
The sea bottom, usually wide, flat, muddy, and unvegetated which is
exposed at low tide; marshy or muddy area that is covered and uncovered
by the rise and fall of the tide.

Tide gate
An opening through which water may flow freely when the tide or water
level is low or high but which will be closed to prevent water from
flowing in the other direction when the water level changes.

Toe, bulkhead
The base of a bulkhead, the lowest part.

155

Tolerance
Relative capacity of an organism to endure or adapt to an unfavorable
environmental factor.

Tombolo
Car or spit connecting an island or structure to the mainland or to
another island.

Toxicant
Substance that kills, injuries, or impairs an organism.

Toxicity
Quality, state, or degree of the harmful effect resulting from alteration
of an environmental factor.

Training works
Structure to direct current flow; see jetty.

Trestle
Braced framework of timbers, piles, or steelwork; see pier.

Turbidity
Deficient in clarity; muddiness, murkiness.

Vertebrate
Animal having an internal skeletel system.

Walers
Horizontal members attached to piles in bulkhead; see Finure 27.

Wave runup
The rush. of water up a structure or beach on the breaking of a wave.

Weep holes
Drainage hole in a structure allowing release of groundwater to prevent
a buildup of water behind the structure.

Weir etty
Xn updrift jetty with a low section or weir over which littoral drift
moves into a pre-dredged deposition basin which is periodically dredged.

Wharf
Structure built on shore so vessels may tie alongside.

Zooplankton
Planktonic animal life.

156 U.S. GOVERNMENT PRINTING OFFICE: 1980-676-972

3
Boston, Mass.
Twin Citi \inn

7.,

--er. Colo.

AlbLiquerque, N. M. A nta, Ga.

Anchorage, Alaska
LEGEND

Headquarters - Office of Biological
Services, Washington, D.C.
0 National Coastal Ecosystems Team,
Slidell. La.
Regional Offices

A Area Office

U.S. FISH AND WILDLIFE SERVICE
REGIONAL OFFICES

REGION I REGION 4 ALASKA AREA
Regional Director Regional Director Regional Director
U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service
Lloyd Five Hundred Building, Suite 1692 Richard B. Russell Building 10 11 E. Tudor Road
500 N.E. Multnomah Street 75 Spring Street, S.W. Anchorage, Alaska 99503
Portland, Oregon 97232 Atlanta, Georgia 30303

REGION 2 REGION 5
Regional Director Regional Director
U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service
P.O. Box 1306 One Gateway Center
Albuquerque, New Mexico 87103 Newton Corner, Massachusetts 02158

REGION 3 REGION 6
Regional Director Regional Director
U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service
Federal Building, Fort Snelling P.O. Box 25486
Twin Cities, Minnesota 5 5 111 Denver Federal Center
Denver, Colorado 80225

OF Tly,
,,t.&T OF
0 DEPARTMENT OF THE INTERIOR"'.
U.S. FISH AND WILDLIFE SERVICE
W1

As the Nation's principal conservation agency, the Department of the Interior has respon-
sibility for most of our,nationally owned public lands and natural resources. This includes
fostering the wisest use of our land and water resources, protecting our fish and wildlife,
preserving the, environmental and cultural values of our national parks and historical places,
and providing for the enjoyment of life through outdoor recreation. The Department as-
sesses our energy and mineral resources and works to assure that their development is in
the best interests of all our people. The Department also has a major responsibility for
American Indian reservation communities and for people who live in island territories under
U.S. administration.

3 6668 00004 5601