• TABLE OF CONTENTS
HIDE
 Front Cover
 Title Page
 Executive summary
 Table of contents
 List of Figures
 List of Tables
 Introduction
 Characteristics of channel deepening...
 Methods
 Historical shoreline changes
 Sediment analysis
 Recommended initial project characteristics...
 Biological considerations
 Recommendations
 Appendix I. Preliminary monitoring...
 Appendix II. Governing equations...






Group Title: UFL/COEL (University of Florida. Coastal and Oceanographic Engineering Laboratory) ; 88/016
Title: Recommendations for placement of dredged sand on Perdido Key Gulf Islands National Seashore
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Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00076128/00001
 Material Information
Title: Recommendations for placement of dredged sand on Perdido Key Gulf Islands National Seashore
Series Title: UFLCOEL
Physical Description: 51 leavles : ill. ; 28 cm.
Language: English
Creator: Dean, Robert G ( Robert George ), 1930-
University of Florida -- Coastal and Oceanographic Engineering Dept
United States -- National Park Service
Publisher: Coastal and Oceanographic Engineering Dept., University of Florida
Place of Publication: Gainesville Fla
Publication Date: 1988
 Subjects
Subject: Shore protection -- Florida   ( lcsh )
Dredging spoil -- Florida   ( lcsh )
Gulf Islands National Seashore (Fla. and Miss.)   ( lcsh )
Coastal and Oceanographic Engineering thesis M.S
Coastal and Oceanographic Engineering -- Dissertations, Academic -- UF
Genre: non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by Robert G. Dean.
General Note: "January 12, 1988."
General Note: Prepared for: National Park Service.
Funding: This publication is being made available as part of the report series written by the faculty, staff, and students of the Coastal and Oceanographic Program of the Department of Civil and Coastal Engineering.
 Record Information
Bibliographic ID: UF00076128
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 26104342

Table of Contents
    Front Cover
        Front Cover
    Title Page
        Page 1
    Executive summary
        Page 2
        Page 3
    Table of contents
        Page 4
        Page 5
    List of Figures
        Page 6
    List of Tables
        Page 7
    Introduction
        Page 8
        Page 9
    Characteristics of channel deepening project and other relevant information
        Page 9
        Page 10
    Methods
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
    Historical shoreline changes
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
    Sediment analysis
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 30
    Recommended initial project characteristics and evolution of the planform
        Page 36
        Page 35
    Biological considerations
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
    Recommendations
        Page 44
        Page 45
        Page 43
    Appendix I. Preliminary monitoring program to quantify physical effects of beach nourishment on Perdido Key
        Page 46
        Page 47
        Page 48
        Page 49
    Appendix II. Governing equations for beach planform evolution
        Page 50
        Page 51
Full Text



UFL/COEL-88/016


RECOMMENDATIONS FOR PLACEMENT OF
DREDGED SAND ON PERDIDO KEY
GULF ISLANDS NATIONAL SEASHORE





By



Robert G. Dean


January 12, 1988






Prepared for:

National Park Service
75 Spring Street, SW
Atlanta, GA 30303

















RECOMMENDATIONS

FOR

PLACEMENT OF DREDGED SAND ON PERDIDO KEY

GULF ISLANDS NATIONAL SEASHORE






January 12, 1988








Prepared For:



National Park Service

75 Spring Street, SW

Atlanta, GA 30303






Prepared By:



Robert G. Dean

Coastal and Oceanographic Engineering Department

University of Florida

336 Weil Hall

Gainesville, FL 32611










EXECUTIVE SUMMARY


This study has evaluated the volumes of beach quality material available
from the dredging planned for the deepening of the Pensacola Bay Entrance
Channel. Recommendations have been made for volumes and configurations of
placement on portions of the Perdido Key Unit of Gulf Islands National
Seashore.

The historical shoreline changes and behavior of the 1985 beach
nourishment have been analyzed to provide an improved basis for developing
recommendations for and predictions of the evolution of any future
nourishment. The following summarize the results and recommendations.


1. The dominant sand transport direction along Perdido Key is from east to
west and in a natural state; the sand supply to the eastern end of Perdido
Key was from Santa Rosa Island across a relatively shallow outer bar.


2. Dredging of the Pensacola Bay Entrance commenced in the 1880's. This
previous deepening has caused an erosional stress on the eastern end of
Perdido Key. Florida Department of Natural Resources data from 1974 to
1984 document erosion rates on the order of 5 ft. per year amounting to at
least 250,000 cubic yards per year. This erosional effect is typical of
shorelines located downdrift of modified entrances.


3. Based on analysis of limited shoreline change data collected by Rutgers
University, it appears that the 1985 nourishment project is performing in
an expected manner with erosion of sand in the region placed, and material
transported to and deposited on adjacent beaches.


4. Results from analysis of aerial photographs are consistent with 2 and 3
above.


5. Based on a field trip and analysis of sediment samples, there do not
appear to be any significant adverse effects as a result of the 1985
nourishment project, with the nourished region revegetating naturally.










6. Based on an analysis of Vibrocore data along the entrance channel, the
material quantities and qualities have been determined as presented in
Tables III and IV.


7. It is recommended that consideration be given to placement of
approximately 5,000,000 yd3 of sand distributed over a beach segment
length of 4.5 miles. After the beach profile has equilibrated, this
should advance the shoreline gulfward by a maximum of approximately
270 ft. This material is of high to excellent quality.


8. In some areas of the dredging, the distribution of high quality material
was not adequately defined by the cores. In these areas it will be
necessary to monitor carefully the dredging operations. If this level of
field vigilance is not considered practical, it is recommended that the
volume placed be reduced to 3,600,000 yd3


9. The recommended initial planform of the placed material is presented in
Figure 12 for a volume of 5,000,000 yd3. The anticipated evolution is
shown in Figure 13.


10. It is recommended that the results of this project be monitored and if the
results document losses in the placed area and transport to the west as
expected, consideration should be given to placing all future maintenance
dredging of good quality material on the eastern end of Perdido Key so as
to reinstate the sediment transport that existed under natural conditions.
A preliminary monitoring plan is presented as Appendix I.











TABLE OF CONTENTS

EXECUTIVE SUMMARY .... ............ .. ...........2.......................... 2

LIST OF FIGURES ............................................ 6
LIST OF TABLES ............................................................ 7
INTRODUCTION........................ ....... ......... ...................... 8
OBJECTIVES AND CRITERIA... .............. ......... ......................... 8

Objectives............................................................ 8
Criteria ........................ ...... ...... .. ...... .......... ...... 8
CHARACTERISTICS OF CHANNEL DEEPENING PROJECT AND OTHER RELEVANT
INFORMATION ....................... .......... ............................. 8
METHODS................... .......... ................................. .... 11

Sand Quality and Quantity.. .............. ...... ........ .... ........... 13
Amount of Acceptable Material Available............................. 15
Station 207+60N to Station 107+90N.............................. 15
Station 107+90N to Station 61+50N................................ 15
Core 26.. .................. ........................... .... 15
Stations 61+50N through Station 23+60N......................... 19
Stations 23+60N through Station 7+60S.......................... 19
Station 7+60S to 41+50S. .......................... .............. 19
Station 41+50S to Station 92+50S................................. 19
Station 92+50S to Station 112+60S................................. 20
Station 112+60S to Station 196+50S.............................. 20
Summary of Available Material Quality........................ ......... 20
HISTORICAL SHORELINE CHANGES.................................. ......... 21

Florida Department of Natural Resources (1974-1984)................... 21
Beach Restoration, Summer 1985....................... ... ............... 21
Shoreline Changes. ....... ............. .. ...... ................ 24
Aerial Photography...................... ............................. 26
SEDIMENT ANALYSIS. ... ...... ...... ...... .......... ..... ...... ............. 30
RECOMMENDED INITIAL PROJECT CHARACTERISTICS AND EVOLUTION OF THE
PLANFORM. .............. ................. ............... ................... 35
Initial Planform........................................... .......... 35
Planform Evolution .. ................................................ 36
Beach Profile................................................. ...... 36
BIOLOGICAL CONSIDERATIONS............. ...... ...... .... ....... ........ .... 36
Emerita Talpoida (Mole Crabs)....................................... 40
Donax (Coquina Clams)..................... ... ............. ... ....... 41
Ocypode Quadrata (Ghost Crabs)....................................... 41











Panama City Studies .................. ............................ 42
Summary Regarding Biological Effects of Beach Nourishment............. 43
RECOMMENDATIONS........................................................... 43
REFERENCES................................................................ 44
APPENDICES
I Preliminary Monitoring Program to Quantify Physical Effects
of Beach Nourishment on Perdido Key.............................. 46
II Governing Equations for Beach Planform Evolution................. 50










LIST OF FIGURES


FIGURE


1. Channel Layout Showing Three Dredging Reaches..................... 10
2. Interior and Gulf Channel Cross-sectional Characteristics......... 12
3. Locations of Vibrocores............................. ........... 14
4. Distribution of Required Total Dredging Pensacola Homeport.
Includes Advance and Allowable Overdepth Dredging Quantities...... 16
5. Distribution of Required Total Dredging Pensacola Homeport and
Quality of Material. Includes Advance and Allowable Overdepth
Dredging Quantities............................................... 17
6. Shoreline Change Rates for Escambia County, January 1974 to
October 1984. Based on Florida DNR Surveys. Note Shoreline
Change Rates Shown Have Been Smoothed by a Five Point Running
Average ........................................................... 22
7. Locations of DNR Monuments and Segment Nourished in 1985.......... 23
8. Example of Evolution of Initially Rectangular Beach Planform
on a Long Uninterrupted Shoreline................................ 25
9. Average Shoreline Changes Over DNR Ranges 61-64 Encompassing
Shoreline Segment of 1985 Nourishment............................. 28
10. Shoreline Position as Determined from Aerial Photography
Analysis.................................... ..................... 31
11. Shoreline Changes in Vicinity of 1985 Beach Nourishment. Based
on Analysis of Aerial Photographs................................. 32
12. Location and Characteristics of Recommended Beach Nourishment..... 37
13. Calculated Evolution of Recommended Nourishment Planform for
Stable and Eroding Beaches. ........................................ 38
14. Recommended Characteristics of Nourished Profile. Illustrated
for DNR Monument No. 48... .................... ............. 39
I-1. Recommended 31 Profile Locations and Location of Directional
Wave Gage......................................................... 48










LIST OF TABLES


TABLE PAGE


I Chronology of Pensacola Bay Entrance Channel Dimensions............. 11
II History of Maintenance Dredging Pensacola Entrance Channel
1975-1987.................... ............... ................ ...... 13
III Summary of Available Material Quality and Quantity Pensacola Bay
Channel Deepening.................... .............................. 18
IV Overall Summary of Material Quantities and Qualities................ 20
V Shoreline Change Data Furnished by Rutgers (Distances in Meters).... 27
VI Plan Area Changes Associated with 1985 Nourishment.................. 29
VII Characteristics of Aerial Photography Used in this Report........... 29
VIII Summary of Sediment Size and Calcium Carbonate Characteristics...... 34
IX Characteristics of Sediment Samples Inside and Outside of 1985
Nourishment Limits................... ........... .............. 35
X Initial Planform Characteristics.................................... 36










RECOMMENDATIONS
FOR PLACEMENT OF DREDGED SAND ON PERDIDO KEY
GULF ISLANDS NATIONAL SEASHORE


INTRODUCTION

Perdido Key is one of a series of barrier islands along the
Florida/Alabama coastline. Under natural conditions the sediment supply for
these islands was maintained by transport from the east and the sand was moved
across channel entrances by waves and currents acting on broad relatively
shallow outer bars of sand. As needs for deeper and more stable navigational
channels developed, these channels were deepened and in some cases stabilized
by jetties which served to train the tidal flows. These modifications
interrupted the natural sediment transport pathway noted above with a
resulting erosion of the downdrift shorelines. This scenario applies to the
eastern end of Perdido Key, where measurements conducted by the Florida
Department of Natural Resources over the 1974-1984 period document rather
severe erosion extending more than 8 miles from the eastern island end. The
forthcoming deepening of the entrance channel to Pensacola Bay to serve as a
homeport for the aircraft carrier Kitty Hawk may further alter natural
processes but also provides the opportunity to compensate for past losses
through placement of fairly large quantities of good quality sand on the
eastern end of Perdido Key. This would be a one-time placement through sand
available from channel deepening. Additionally, based on experience, it is
likely that good quality maintenance material will be available periodically
to serve to reinstate the natural sediment supply. It is important to the
quality of Perdido Key to identify the appropriate amounts and placement
locations of the sand available from the channel deepening and maintenance
dredging. The criterion, consistent with National Park Service policy, is to
reinstate, in as natural a manner as possible, the longshore sand flow to the
island and to regain a reasonable amount of the sand eroded due to past
modifications and dredging practices in the entrance channel.










OBJECTIVES AND CRITERIA
Objectives

The objectives of the present study are:


(1) To review the shoreline change history at the eastern end of Perdido Key.


(2) To quantify that portion of shoreline changes associated with past
channel maintenance and sand management practices.


(3) Consistent with National Park Service policy, to develop recommendations
for the amounts and placement locations of sand resulting from: (a) the
channel deepening, and (b) periodic maintenance dredging.


Criteria

The broad criteria employed in approaching the objectives above are:


(1) To utilize an appropriate amount of the forthcoming channel deepening
material to reestablish the island in the condition that would have
prevailed if the long-term dredging had not occurred.


(2) Within existing constraints, to reinstate the natural sand transport
quantities in the vicinity of the eastern end of Perdido Key. This
criterion would apply primarily to the maintenance dredging.


CHARACTERISTICS OF CHANNEL DEEPENING PROJECT AND OTHER RELEVANT INFORMATION

The Pensacola Bay Entrance Channel has been a Federally authorized
channel since 1881. Table I presents the dates associated with various
authorized and excavated channel depths and widths.

The channel associated with the Kitty Hawk homeporting extends from the
berthing docks inside Pensacola Bay westward then southward around the western
end of Santa Rosa Island and finally south-southwest to a natural water depth
of 48 ft. As presented in Figure 1, the total channel length is approximately
7.7 miles and extends an approximate distance of 4 miles gulfward of the
Perdido Key shoreline. Two channel cross-sections are incorporated into the
design. From the berthing area to slightly east of the western tip of Santa










OBJECTIVES AND CRITERIA
Objectives

The objectives of the present study are:


(1) To review the shoreline change history at the eastern end of Perdido Key.


(2) To quantify that portion of shoreline changes associated with past
channel maintenance and sand management practices.


(3) Consistent with National Park Service policy, to develop recommendations
for the amounts and placement locations of sand resulting from: (a) the
channel deepening, and (b) periodic maintenance dredging.


Criteria

The broad criteria employed in approaching the objectives above are:


(1) To utilize an appropriate amount of the forthcoming channel deepening
material to reestablish the island in the condition that would have
prevailed if the long-term dredging had not occurred.


(2) Within existing constraints, to reinstate the natural sand transport
quantities in the vicinity of the eastern end of Perdido Key. This
criterion would apply primarily to the maintenance dredging.


CHARACTERISTICS OF CHANNEL DEEPENING PROJECT AND OTHER RELEVANT INFORMATION

The Pensacola Bay Entrance Channel has been a Federally authorized
channel since 1881. Table I presents the dates associated with various
authorized and excavated channel depths and widths.

The channel associated with the Kitty Hawk homeporting extends from the
berthing docks inside Pensacola Bay westward then southward around the western
end of Santa Rosa Island and finally south-southwest to a natural water depth
of 48 ft. As presented in Figure 1, the total channel length is approximately
7.7 miles and extends an approximate distance of 4 miles gulfward of the
Perdido Key shoreline. Two channel cross-sections are incorporated into the
design. From the berthing area to slightly east of the western tip of Santa





























































Channel Layout Showing Three Dredging Reaches


Figure 1.










TABLE I
CHRONOLOGY OF PENSACOLA BAY ENTRANCE
CHANNEL DIMENSIONS

Channel Dimensions Authorized
Year
Depth (ft.) Width (ft.) or Actual

1881 24 80 Authorized

1885 22.5 80 Actual

1890 24 120 Actual

1896 30 300 Authorized

1902 30 500 Authorized

1935 32 500 Authorized

1959 37 800 Actual

Present 44 800 Authorized



Rosa Island, the nominal depth is 42 ft below MLW; for the remainder of the
channel length to its Gulf terminus, the nominal depth is 44 ft. The actual
dredged depths will include an additional 2 ft for "advance maintenance" and
an additional 2 ft for "allowable overdredging". Thus, as presented in Figure
2a and 2b the dredged depths for the two cross-sections will be 46 ft and 48
ft. The total anticipated dredging for the project is in excess of 13.3
million cubic yards. It is anticipated that the deepening project will
commence in October 1988 and continue through 1990. A maintenance dredging
project of approximately 200,000 yd3 was conducted in November-December, 1987
with offshore placement. Table II presents the history of maintenance
dredging over the period 1975 to 1987.


METHODS

The overall methods included a site visit, review and analysis of prior
studies in the area including data collected by Rutgers, and computations of
the behavior and effects of sand placement. The detailed methodology employed
and results obtained are presented in the following sections of this report.








Ambient Bottom
(Varies in Elevation)





I--- 800ft ---800 t
5 5
.--------------------------------. 42 ft Project Depth
--- 44 ft Includes 2 ft Advance Maintenance Dredging
i -46 ft Including 2 ft Allowable Overdredging

a) Interior Channel Characteristics



[10-
0 i1




I. 0 200
S______Horizontal and
81 t 1 Vertical Scales
In feet
5 5
---------------------------------- ----44 ft Project Depth
44 ftProject Depth
46 ft Includes 2 ft Advance Maintenance Dredging
... .. .. .. .. .. i-.- 48 ft Including 2 ft Allowable Overdredging

b) Gulf Channel Characteristics


Figure 2. Interior and Gulf Channel Cross-sectional Characteristics.










TABLE II
HISTORY OF MAINTENANCE DREDGING
PENSACOLA ENTRANCE CHANNEL
1975-1987

Year Volume Dredged Type Dredge Disposal Area
(yd3)

1975 1,100,000 Hopper Gulf Disposal
1981 647,000 Hopper Gulf Disposal
1983 114,000 Hopper Gulf Disposal
1984 917,000 Hopper Gulf Disposal
1985 2,433,000 Pipeline Perdido Key
1987 200,000 Hopper Gulf Disposal
(approx.)


Sand Quality and Quantity

As a first determinant of the amount of sand to be placed during the
channel deepening phase, an effort was carried out to quantify the amount of
good quality sand available which could feasibly be placed on Perdido Key.
This would represent the upper limit of material to be recommended. Sand
quality as used here is based on grain size and visual evidence, primarily
color which is a good indicator of organic content.

The bases for determination were the vibrocore data and quantities to be
dredged. Figure 3 presents the overall layout of the channel and the
locations of the vibrocores. The quality of material in each of the cores was
defined by: (a) logs or general description from visual inspections of the
cores, (b) size analyses at several depths along the cores, and (c) color
photographs along the entire length of the cores. The latter proved to be
invaluable.

Prior to discussing available sand characteristics, it is relevant to
note that, as shown in Figure 1, the entrance channel had been defined in
three reaches, with the central reach, Reach 2, as that reach which could
provide sand to Perdido Key. The boundary between Reach 1 and Reach 2 had
been established earlier based on material quality, reportedly in discussions
with the State of Florida. The boundary between Reach 2 and Reach 3 was based
on economic considerations, i.e. seaward of this juncture it is considered to


I


































































Figure 3. Locations of Vibrocores.


14










be less costly to transport sand seaward than to Perdido Key. Figure 4
presents an estimate of the volumetric distribution of sand dredging required
as a function of position along the channel.


Amount of Acceptable Material Available

As described briefly previously, the amount of acceptable quality
material expected to be available for placement on the beach was developed
primarily through examination of vibrocore information at the 48 locations
shown in Figure 3.

As might be expected, it would always be helpful to have more information
to define completely the distribution of acceptable material in the planned
dredge area. However, it is believed that with the data presently available
it is possible to identify sufficient quantities of good quality sand to meet
the objectives of this study. In those limited areas where uncertainties
remain, it will be necessary to maintain flexibility in the field operations
with special monitoring during dredging. If the Corps/Navy is unwilling to
maintain this flexibility and field vigilance, it will be recommended that
these areas of uncertainty be deleted from further consideration.

Figure 5 is an annotated version of Figure 4 and includes description of
the quality of the material. Several areas can be grouped as presented below
and summarized in Table III.

Station 207+60N to Station 107+90N The material characteristics within
these stations are described by cores 1-19 and although there is some good
material in this area, the locations of acceptable material are somewhat
spotty and it is recommended that all of this material in this segment be
regarded as unacceptable. It is noted that this length of undesirable
material is greater than previously identified as Reach 1.

Station 107+90N to Station 61+50N The quality of material within this
4,640 ft segment is defined by Vibrocores 20 through 25. The material
contained in these cores is uniformily good down to an elevation of -48 ft
which is the greatest dredging depth considered in this segment. The amount
of material expected to be dredged in this segment is 1,250,000 yd3

Core 26 This vibrocore was taken on the westerly side of the
navigational channel and is uniformily very poor. Referring to Figure 4, it



















I'.1
50-


W
0 ,

500-


200 100 0 100 200


Station South

---- Reach 3


Station North


Reach 2


F"`


Distribution of Required Total Dredging Pensacola Homeport. Includes Advance and Allowable
Overdepth Dredging Quantities.


Pensacola Naval Air Station

240(7 S25+60N


Perdido
Key


Reach 3


Sta. 196+50S


Figure 4.


Reach 1


~I~






















W




0,

500-


All Acceptable
ve Elevation: 41 ft


Unacceptable
(Core 26)


200 100 0 100 200
Station South Station North


Reach 2


Reach 1


Distribution of Required Total Dredging Pensacola Homeport and Quality of Material. Includes Advance
and Allowable Overdepth Dredging Quantities.


Pensacola Naval Air Station

2400 Ste.125+60N
VReach2 \


Island


Reach 3


Sta. 196+50S


-- Reach 3


Figure 5.


_I_


F B










TABLE III
SUMMARY OF AVAILABLE MATERIAL QUALITY AND QUANTITY
PENSACOLA BAY CHANNEL DEEPENING


Stations Material Quality Volumes of Material
Defined by Cores in Segment (yd3) Comments
From To From To Total Acceptablet
From To From To Total Acceptable


4,540,000



1,250,000
330,000


1,070,000
1,490,000

1,000,000
1,590,000
470,000

270,000


220,000


220,000
70,000
negligible


0



1,250,000
0


1,070,000
600,000

1,000,000
1,590,000
260,000

270,000


160,000


220,000
0
negligible


All material unacceptable. Segment
limits expand those previously defined
for unacceptable material.
All material uniformily good.
All material unacceptable. Limits not
well-established.
All material acceptable.
Only material above -41 ft elevation
recommended for beach placement.
All material of good quality.
All acceptable.
Material above elevation -44
unacceptable, remainder acceptable.
All of good quality, but probably too
localized for beach placement.
Top 2 ft of poor quality, rest
acceptable.
Good quality.
All of poor quality.
Top 7 ft of acceptable quality,
remainder unacceptable.


207+60N



107+90N



61+50N
23+60N

7+60S
41+50S
92+50S




112+60S


107+90N



61+5 0N



23+6 0N
7+60S


41+50S
92+50S
112+60S




196+50S


I










is seen that this core corresponds to an area of maximum dredging. For
purposes of estimation at this location, one-half of the material has been
considered as characterized by Core 26 and one-half by Cores 25 A and B. This
is an area where better definition would be desirable and it will be necessary
to recognize that a portion of the material in this section of the channel
will be acceptable and a portion will not be suitable for placement on the
beach. With the definition allowed by the present cores, this determination
must be made in the field. This will require special consideration and field
care in this area; if it is not practical to retain this flexibility, it is
recommended that the material in this segment be deleted from consideration
for beach placement.

Stations 61+50N through Station 23+60N The material in this segment as
defined by Vibrocores 27 through 28 is consistently good. It is estimated
that 1,070,000 yd3 of material, all suitable for beach placement, will be
yielded in this segment.

Stations 23+60N through Station 7+60S The material in this segment is
described by Vibrocores 29 through 32. The material in the upper portions of
each of these four cores is of good quality but that below elevations ranging
from -41 ft to -45 ft is unacceptable. Two possibilities are present here.
The first would be to place that material above the -41 ft horizon on the
beach and to dispose of the additional material elsewhere. The alternative
would be to place none of this material on the beach. It is estimated that
600,000 yd3 of good quality sand could be produced above the -41 ft horizon.

Station 7+60S to 41+50S Vibrocores 33 36 define the material
characteristics in this segment. All of this material is acceptable. The
southerly limit of this segment was defined by the earlier established
boundary between Reach 2 and Reach 3. It is recalled that this had been
determined as the break-point south of which it would be more economical to
dispose of the material at sea. The estimated quantity of good quality
material in this segment is 1,000,000 yd3

Station 41+50S to Station 92+50S The material characteristics in this
segment are described by Vibrocores 37 41 and are uniformily good down to
the base channel elevation. It is estimated that 1,590,000 yd3 of high
quality material are available in this segment.










Station 92+50S to Station 112+60S The material characteristics in this
segment are defined by Vibrocores 42 and 43. There is a top layer of poor
quality material underlain by good sand. The elevation of the interface
ranges between -42 to -44 ft and for this situation, it would be feasible to
remove the top layers, say down to -44 ft, with disposal offshore and place
the underlying material on the beach. It is estimated that the volume of
acceptable material is 260,000 yd3

Station 112+60S to Station 196+50S The total quantity of material in
this segment is relatively small (760,000 yd3) and is fairly irregular in
quality. In particular, all of Core 44 is of good quality. The top 2 ft of
Core 45 is of poor quality yet the remaining material is acceptable. Core 46
appears good, Core 45 is all of poor quality, Core 48 is of good quality for
the top 7 ft and poor for the underlying layers and finally Core 48 appears
uniformily bad. It is recommended that none of this material be placed on
Perdido Key.


Summary of Available Material Quality

Table III presents a summary of material quality along the channel and
Table IV provides additional summarized information.


TABLE IV
OVERALL SUMMARY OF MATERIAL QUANTITIES AND


QUALITIES


Description of Material Characteristics Total Volume (yd3)


Total volume to be dredged 13,300,000
Total volume acceptable 6,420,000
Total volume acceptable within Reach 2 3,920,000
Total volume acceptable in Reach 2 without
special care 3,320,000
Total volume acceptable if extend limits of
Reach 2 to 92+50S 5,510,000
Total volume acceptable without special care if extend
limits of Reach 2 to 92+50S 3,660,000


I










HISTORICAL SHORELINE CHANGES


This section reviews various sources of data from which one can infer
historical rates of shoreline change.


Florida Department of Natural Resources (1974-1984)

The Division of Beaches and Shores of the Florida Department of Natural
Resources maintains a monumented baseline along those 24 counties in Florida
which have predominantly sandy shorelines. The monuments are at nominal
spacings of 1,000 ft and provide an excellent base from which to conduct
repetitive measurements of shoreline position. In Escambia County, complete
sets of measurements have been conducted in 1974 and 1984. The results are
presented for the eastern end of Perdido Key in terms of annual rates of
shoreline changes in Figure 6. The monument locations along Perdido Key and
Santa Rosa Island are presented in Figure 7. The results, which have been
smoothed, show an average erosion rate on the order of 4 to 5 ft. per year
decreasing toward the west. Near DNR monument 64, there is an area where
accretion had occurred during the 10 year period. This area is located in the
vicinity of Caucus Shoals and it is believed that this is an anomalous
feature. Within the seven mile region shown in Figure 6, the loss in plan
area is approximately 150,000 ft2/year, which using a conventional "rule for
thumb" suggests an approximate volumetric loss of 150,000 cubic yards
annually. Although not shown in Figure 6, the additional loss rate west of
DNR monument 30 is at least 100,000 cubic yards per year. This is consistent
with prevailing estimates of the net annual longshore sediment transport in
this area at approximately 200,000 yd3/year toward the west.


Beach Restoration, Summer 1985

In July, 1985, in conjunction with maintenance dredging, approximately
2.4 million cubic yards of generally good quality sand was placed along the
eastern end of Perdido Key. Placement occurred over approximately 4,000 ft of
shoreline length. At the time of placement, the eastern end of Perdido Key
was in a fairly advanced state of erosion as a result of the impact of
interruption of the natural littoral transport from the east by dredging of
the navigational channel. Unfortunately, there has been no concerted effort
to document the performance of this project; however, in conjunction with












+5.0

t


-5.0


30 40 50 60


FLORIDA DNR MONUMENT NUMBER


Shoreline Change Rates for Escambia County, January 1974 to October 1984.
Florida DNR Surveys. Note Shoreline Change Rates Shown Have Been Smoothed
Point Running Average.


Figure 6.


Based on
by a Five

























N





I o de
Figure 7. Locations of DNR R40Monuments and Segment Nourished in 1985.
-.zo Beach Segm
RIO 0 Nourished in





Figure 7. Locations of DNR Monuments and Segment Nourished in 1985.










their National Park Service responsibilities, investigators from Rutgers have
conducted limited measurements, the analysis of which will be discussed in
later paragraphs. Hurricane Elena occurred in September, 1985, shortly after
completion of the project. Although the effects of this hurricane on Perdido
Key were substantial, it is believed that the eastern end of Perdido Key would
have suffered much more degradation if the restoration project had not been in
place.

Shoreline Changes Information provided by Rutgers included shoreline
position measurements at 33 locations of monuments maintained by the Florida
Department of Natural Resources. These monuments are numbered 34 through 66
and are approximately 1,000 ft apart; see Figure 7. The 1985 restoration
segment encompassed Monuments 61 through 64. Rutgers provided survey
information for the following dates


October 1984
April 1985 (Pre-nourishment)*
September 1985 (Post-nourishment and post Hurricane Elena)
May 1986
September 1986
February 1987
July 1987
(*Note: Nourishment occurred in July 1985)


Prior to presenting the analysis of the Rutgers results, a brief
presentation will be made of the expected behavior of an idealized beach
restoration project on a long straight shoreline. Figure 8 presents as a bold
line an idealized initial rectangular planform distribution of a nourishment
project. For the idealized case of an infinitely long coastline, a simplified
solution (summarized in Appendix II) is available for the evolution of this
planform. An example of the solution is presented as the additional lines in
Figure 8. It is seen that the sand spreads laterally, nourishing the adjacent
beaches as a result of sand transported out of the nourished area. The rate
at which this evolution occurs depends on the wave height raised to the 2.5
power, and inversely on the project length. As mentioned, actual project
behavior deviates from the idealized results presented above; however, the
idealized treatment provides a framework against which to evaluate actual
















0
Or
o


M 00 -
0 0=

y(ft) M o m_
0

O C
7:'
_________/3 __
.- / ,/./4 0- |


0 20"
.... I:, ,-



-2.0 -1.0 0 1.0 2.0

ALONGSHORE DISTANCE (miles)


Figure 8. Example of Evolution of Initially Rectangular Beach Planform on a Long Uninterrupted Shoreline.










performance. Detailed results from the idealized solution will be used to
evaluate the 1985 nourishment project.

The Rutgers' tabulated results for shoreline position are presented as
Table V. Prior to analyzing these data, several features are noted. The
positions are presented for the NGVD (National Geodetic Vertical Datum)
contour, which is approximately the mean sea level contour. All positions are
relative to April, 1985. Although a separate column is not presented for the
April survey, if it were, all entries would be zeros, since these are the
reference values.

It is evident, examining the September 1985 survey, that the nourishment
took place over DNR monuments 61-64 a distance of approximately 4,000 ft.

As a visual indication of the evolution of the beach fill over time, the
average shoreline change over FDNR ranges 61-64 has been plotted in Figure 9.
It is seen that the shoreline eroded an average of about 82 ft from October
1984 to April 1985, followed by an increase of approximately 525 ft due to the
nourishment project. During the subsequent 1.8 years (September 1985 to July
1987), the shoreline within Ranges 61-64 eroded approximately 197 ft.

An additional simple and informative result is obtained by establishing
the percentage loss of sediment within the area placed. Considering sand to
have been placed in the area represented by FDNR range monuments 61-64, the
results presented in Table VI are obtained.

Based on the results of Table VI, by July 1987 approximately 35% of the
material present in September 1985 was transported out of the nourished
segment. Using results from the idealized analysis described in Appendix II,
an effective wave height of approximately 1.1 ft can be determined as a
mobilizing agent for the placed sand. This effective wave height will be
useful in later calculations of evolution of a nourishment project.


Aerial Photography

Aerial photography of the area was provided by the U.S. Army Corps of
Engineers for the periods 1969, 1976, 1985 and 1986. In addition for purposes
of this study, additional black and white and color photography was flown in
October, 1987. The dates, scales and other information relevant to this
photography are presented in Table VII.








TABLE V


SHORELINE CHANGE DATA
(Distances


FURNISHED BY RUTGERS
in Meters)


ngvd change Apr 85 (datum)
DNR
monument oct 84 sep 85 may 86 sep 86 feb 87 jul 87


34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66


8.390
-8.800
-20.470
-1.910
-17.720
-3.920
-0.340
-6.300
-20.650
-3.350
-12.880
-2.490

-2.840
-17.430
-8.880
-5.250
-0.650
-7.620
7.540
9.080
19.790
5.860
4.880
13.760

-2.480
16.660
25.690
33.020
30.220
-9.990
15.620


-2.840
4.130
-10.850
-9.400
-7.030
-10.470
0.300
-0.010
-0.160
-2.530
-1.690
-3.270

-5.660
-9.390
-8.030
-9.310
17.720
-20.260
-8.070
-3.200
-8.000
-5.520
-21.470
-19.150
11.650
53.260
117.560
169.810
186.070
175.740
-0.580
-9.910


-19.320
-14.220
-21.550
-18.150

-18.790

-14.780
-14.950
-8.650
-19.590
-16.620

-27.090
-22.900
-13.060
-22.760
-25.190
-17.940
-21.540
-19.890
-15.480
-12.880
-25.590
-5.890
18.240
40.680
101.080
131.900
148.530
129.620


-16.110
-10.160
-18.750
-22.550


-9.520
-15.280
-14.340
-3.120
-19.200
-14.140


-13.320
-9.870
-12.000
-27.280
-21.030
-22.620
-23.130
-10.750
-13.860
-9.910-

0.960
33.420
68.000
132.970
143.430
146.980
121.080
-1.080
20.140


-1.660
-8.150
-21.130
-11.890
-18.100
-3.910
-7.350
-10.030
-23.460
-15.000
-24.650
-17.420

-21.670
-22.370
-4.370
-12.380
-5.070
-11.060
10.850
7.160
-4.280
-1.410
-9.130
-8.580
18.700
45.780
97.300
107.770
107.090
119.640
2.750


-12.85
-12.61
-22.73
-19.11
-20.72
-13.01
-8.25
-12.12
3.61
-8.31
-7.43
-3.87


-3.17
-7.42
-1.81
-14.2Q.
-11.71
-31.38
-11.06
-8.91
-5.8
-3.07
-8.95
3.51
28.32
54.71
97.36
114.70
113.37
94.09
-12.56


'

















0


It
IT-.
wE

Oc
0 o
ro

x o

a
4e.
g! |
<1c


600

500-


400

300-

200

100


0


a 100


Hurricane
Elena



I 0. o

z
I


- i


S200 J F MAMJ J ASO ND J FMA MJ J A SOUND J FM AMJ J AS ONDJ FMA MJ J AS
1984---- -1985 ---1986 --1987


Figure 9. Average Shoreline Changes Over DNR Ranges 61-64 Encompassing Shoreline Segment of 1985
Nourishment.


1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I I I I I I I I I I I I I I I l l I I I I I I


1


0\


m

















TABLE VI
PLAN AREA CHANGES ASSOCIATED WITH 1985 NOURISHMENT

Dates Plan Area Changes (ft2)

April 1985 to September 1985 + 2,128,400 ft2
September 1985 to July 1987 753,400 ft2


TABLE VII
CHARACTERISTICS OF AERIAL PHOTOGRAPHY USED IN


THIS REPORT


Photography Date Scale Type Comments

April 1969 1:12000 Black and White Eastern 8,000 ft of
Island Not Covered

March 1977 1:24000 Color All of Park System
Covered

September 1985 1:12000 Black and White All of Park System
Covered

March 1986 1:12000 Color All of Park System
Covered

October 1987 1:24000 Black and White All of Park System
Covered

October 1987 1:12000 Color All of Park System
Covered










The aerial photographs were digitized, adjusted to a common scale,
plotted and are presented in Figure 10. The correct alignment of the
photographs is critical to an accurate determination of shoreline changes and
for this purpose a road intersection was used on the western end of the region
of interest and an identifiable feature on Fort McRee was used on the eastern
end. As noted in Table VI, the 1969 photography did not include the eastern
8,000 ft of the island. This has resulted in less confidence in the
photography alignment, with these uncertainties greatest toward the east.
Additionally, the generally small scale of all but the 1987 aerial photography
results in relatively low confidence in quantitative shoreline changes.

The aerial photographs were analyzed to determine the shoreline changes
in the vicinity of the 1985 beach nourishment. These results are presented in
Figure 11 for the time intervals 1977 to 1985 and 1985 to 1987. The first
time period includes the 1985 nourishment and Hurricane Elena. It is seen
that the ambient erosion over the 1977 to 1985 period (8.5 years) is on the
order of 150-200 ft., part of which may be attributed to the erosional trend
in this area and part due to the impact of Hurricane Elena. The nourishment
has spread out beyond the limits where it was placed and also more than
compensates for the erosion in the placement area. During the 1985 to 1987
interval, erosion has occurred in the nourished area and the adjacent
shoreline has been relatively stable. This time interval (2.1 years) is too
short to develop quantitative results; however, it is clear that a portion of
the nourished area has eroded and appears to be of benefit to the adjacent
shorelines. In summary, the results of the aerial photography analysis are in
qualitative agreement with the more reliable survey data of Florida DNR and
Rutgers.


SEDIMENT ANALYSIS

During the field visit, 32 sediment samples were taken both within and
outside of the 1985 nourished area. These samples generally extended across
the beach profile and included material from the dune, berm, beach face and
offshore bar. These samples were subsequently analyzed by Thompson
Engineering Testing, Inc. (Job #1666-A87670, Report No. 1) for size
distribution and calcium content. It had been reported that the calcium
carbonate (shell) content of the nourishment material was significantly higher





















Escambia County, Perdido Key Sacle: 1"=4000ft.








S..

I I I I I I I I I I I I I I I I I I I I I II I I I II I I I I I 7
1969/04 Photos
1977/03 Photos
+ = Locations of Florida DNR Monuments 1985/09 Photos
1986/03 Photos
------- 1986/03 Photos
FLORIDA DNR MONUMENT NUMBER 1987/10 Photos

I I I I I I I I I I I 1 i I I I I I I I I I I I I I I


Figure 10. Location and Characteristics of Recommended Beach Nourishment.

















West
<--~


Approximate Limits
,oS 1985 Nourishmept"


I -I

March 1977 to Sept. 1985
(Includes 1985 Nourishment
and Hurricane Elena)



L


\ --NSept. 1985 to October 1987


~~ -


1Iii 1 Mile -1


I I I I I I I I I I I I I I I


DNR RANGE MONUMENT NUMBER


Figure 11.


Shoreline Changes in Vicinity of 1985 Beach Nourishment. Based on
Analysis ot Aerial Photographs.


+500O


-500


- -


-










than the native material and therefore quantification of this parameter was of
interest. The locations of the samples and the median size and calcium
carbonate content are presented in Table VIII. Column 4 indicates whether or
not the sample was located in the 1985 nourishment area. The samples RX-1,2,3
were located adjacent to the Park Headquarters.

In order to determine whether or not the nourished material was
significantly different than the native properties (median diameter and
calcium carbonate), these properties were averaged for common positions across
the beach profile for areas within and outside of the 1985 nourishment
limits. These results are presented in Table IX.

Prior to discussing the averages, it should be noted that there is
significant variability in some of the individual parameters, especially the
calcium carbonate content. Returning to Table IX, the only significant
differences in diameter are for "Near the Dune Line". Presumably the reason
is that outside the fill area, these sediments have been transported by wind;
as a result only the smaller grains have been transported to and deposited in
this area. The similar grain sizes on the beach face could be the result of
the relatively high transport activity in this region. Although the diameters
"midway across the berm" within the fill limits are slightly coarser than
outside, it is somewhat surprising that these differences are not greater.
The diameters at the five foot depth, usually on the bar, are essentially the
same inside and outside of the fill limits. This is due to offshore transport
of the finer material, leaving the coarser material on the more energetic
beach face. With the exception of the beach face and five foot depth, the
average calcium content is substantially higher within the fill limits. This
is consistent with (1) the active transport on the beach face, and (2) the
selective transport of the finer materials offshore and the tendency for the
shells to be coarser than the sand.

In summary, although the sediment properties did exhibit some differences
within and outside of the fill limits, they are not so large as to be regarded
negatively. Moreover, with the beach system exposed to a wider range of storm
and normal wave processes, it is anticipated that any noticeable differences
will tend to diminish with time.










TABLE VIII


SUMMARY OF SEDIMENT SIZE AND CALCIUM CARBONATE CHARACTERISTICS

Sample Percent Median In 1985 Comments
Designation Calcium Size, D50 Nourishment
Carbonate (mm) Area?

R61-1 2.2 0.49 Yes Near Old Dune Line
R61-2 2.8 0.38 Yes Midway on Fill to Water
R61-3 4.5 0.51 Yes Beachface
R61-4 < 0.2 0.31 Yes Bar Crest, Approx. 5 ft
Depth

R62.5-1 0.3 0.49 Yes Near Old Dune Line
R62.5-2 0.5 0.41 Yes Midway on Fill to Water
R62.5-3 5.2 0.50 Yes Beachface
R62.5-4 0.4 0.31 Yes Bar Crest, Approx. 5 ft
Depth

R64-1 0.2 0.33 Yes Near Old Dune Line
R64-2 0.2 0.33 Yes Midway on Fill to Water
R64-3 3.9 0.54 Yes Beachface
R64-4 0.2 0.32 Yes Bar, Approx. 5 ft Depth
R64-5 < 0.2 0.30 Yes Natural Dune

R67-1 < 0.2 0.33 No Near Dune Line
R67-2 < 0.2 0.37 No Midway from Dune to Water
R67-3 1.0 0.33 No Beachface
R67-4 < 0.2 0.37 No Approx. 5 ft Depth, No
Bar

R65-1 < 0.2 0.30 No Near Dune LIne
R65-2 < 0.2 0.31 No Midway from Dune to Water
R65-3 5.4 0.35 No Beachface
R65-4 < 0.2 0.25 No Approx. 5 ft Depth, No
Bar

R57-1 < 0.2 0.36 No Near Dune Line
R57-2 < 0.2 0.37 No Midway from Dune to Water
R57-3 3.3 0.45 No Beachface
R57-4 0.2 0.30 No Outer Bar Crest, Approx.
5 ft Depth

R55-1 < 0.2 0.36 No Near Dune Line
R55-2 < 0.2 0.32 No Midway from Dune to Water
R55-3 4.2 0.50 No Beachface
R55-4 0.2 0.30 No Outer Bar Crest, Approx.
5 ft Depth

RX-1 0.2 0.37 No Beach, No Dune
RX-2 1.9 0.45 No Beachface
RX-3 0.4 0.29 No Outer Bar Crest, Approx.
5 ft Depth










TABLE IX
CHARACTERISTICS OF SEDIMENT SAMPLES
INSIDE AND OUTSIDE OF 1985 NOURISHMENT LIMITS

Beach Profile Median Diameter (mm) Calcium Carbonate Percentage

Feature Inside Fill Limits Outside Inside Fill Limits Outside

Near Dune Line 0.44 0.34 0.9 < 0.2
Midway Across Berm 0.37 0.35 1.17 < 0.2
Beach Face 0.44 0.42 3.3 3.2
Bar Crest or Five
Foot Water Depth
if Bar Not
Present 0.31 0.30 0.3 0.2



RECOMMENDED INITIAL PROJECT CHARACTERISTICS AND EVOLUTION OF THE PLANFORM

Initial Planform

The most relevant parameters of the initial planform are the length, ,
the width, w, and the transition characteristics at the end of the project.
Using accepted procedures, the additional width, w, for various lengths and
nourishment quantities are presented in Table X. To provide a basis for
comparison, the average shoreline advancement associated with the 1985
nourishment was approximately 525 ft.


TABLE X
INITIAL PLANFORM CHARACTERISTICS


Project Additional Beach
Volume Placed Length Width
(yd3) (miles) (ft)

4 95 ft
2,000,000 6 60 ft

4 180 ft
4,000,000 6 120 ft

4 285 ft
6,000,000 6 180 ft

5,000,000 4.5 270 ft*
(with tapered ends)

*Recommended Plan










The aerial photographs were digitized, adjusted to a common scale,
plotted and are presented in Figure 10. The correct alignment of the
photographs is critical to an accurate determination of shoreline changes and
for this purpose a road intersection was used on the western end of the region
of interest and an identifiable feature on Fort McRee was used on the eastern
end. As noted in Table VI, the 1969 photography did not include the eastern
8,000 ft of the island. This has resulted in less confidence in the
photography alignment, with these uncertainties greatest toward the east.
Additionally, the generally small scale of all but the 1987 aerial photography
results in relatively low confidence in quantitative shoreline changes.

The aerial photographs were analyzed to determine the shoreline changes
in the vicinity of the 1985 beach nourishment. These results are presented in
Figure 11 for the time intervals 1977 to 1985 and 1985 to 1987. The first
time period includes the 1985 nourishment and Hurricane Elena. It is seen
that the ambient erosion over the 1977 to 1985 period (8.5 years) is on the
order of 150-200 ft., part of which may be attributed to the erosional trend
in this area and part due to the impact of Hurricane Elena. The nourishment
has spread out beyond the limits where it was placed and also more than
compensates for the erosion in the placement area. During the 1985 to 1987
interval, erosion has occurred in the nourished area and the adjacent
shoreline has been relatively stable. This time interval (2.1 years) is too
short to develop quantitative results; however, it is clear that a portion of
the nourished area has eroded and appears to be of benefit to the adjacent
shorelines. In summary, the results of the aerial photography analysis are in
qualitative agreement with the more reliable survey data of Florida DNR and
Rutgers.


SEDIMENT ANALYSIS

During the field visit, 32 sediment samples were taken both within and
outside of the 1985 nourished area. These samples generally extended across
the beach profile and included material from the dune, berm, beach face and
offshore bar. These samples were subsequently analyzed by Thompson
Engineering Testing, Inc. (Job #1666-A87670, Report No. 1) for size
distribution and calcium content. It had been reported that the calcium
carbonate (shell) content of the nourishment material was significantly higher










Planform Evolution

Considering the nourishment to occur over a beach segment encompassed by
FDNR Ranges 40 through 64 (4.5 miles), the recommended planform is presented
in Figure 12 and the anticipated evolution is presented in Figure 13. Figure
13a presents the planform at 2, 5 and 10 years for an otherwise stable shore-
line and Figure 13b presents the planform at the same time periods for the
more realistic case of a shoreline eroding at 5 ft. per year. In Figure 13,
the shoreline has been drawn straight for convenience rather than curved.
Also, the jetty at the northeastern end of Perdido Key (near DNR monument 67
is included).

Beach Profile

The planform characteristics presented in the preceding section and in
Table X have been based on the consideration that one cubic yard of sand along
one foot of beach length will cause a shoreline advancement of one foot.
Thus, this one cubic yard (27 cubic feet) is distributed such that it causes a
uniform profile advancement of one foot over a vertical portion of the profile
of 27 ft. The placement options include placing the material to a shallower
depth which means that the shoreline advancement must be greater. With this
placement strategy, the waves will ultimately redistribute the sand to greater
depths to yield the one foot shoreline advancement per cubic yard of sand per
unit length of beach. Figure 14 shows these two options and the recommended
profile shoreward of the equilibrated position of the initial shoreline. The
purpose of the lower berm (4 to 5 ft.) compared to the natural berm height
(approximately 6 ft.) is to allow the wind and water processes to exert their
respective shaping processes, thereby yielding a more natural profile.

BIOLOGICAL CONSIDERATIONS

No specific studies have been conducted to determine the effect of the
1985 beach nourishment on the biology of Perdido Key. However, monitoring
studies have been conducted of other projects and these results allow the
probable impact to be inferred.

The information below is drawn primarily from an excellent review by
Nelson (1985) of the effects of beach nourishment on the nearshore biota. The
primary focus will be on three common nearshore organisms: (1) Emerita
talpoida (mole crabs), (2) Donax (coquina clams), and (3) Ocypode (ghost
crabs).










TABLE IX
CHARACTERISTICS OF SEDIMENT SAMPLES
INSIDE AND OUTSIDE OF 1985 NOURISHMENT LIMITS

Beach Profile Median Diameter (mm) Calcium Carbonate Percentage

Feature Inside Fill Limits Outside Inside Fill Limits Outside

Near Dune Line 0.44 0.34 0.9 < 0.2
Midway Across Berm 0.37 0.35 1.17 < 0.2
Beach Face 0.44 0.42 3.3 3.2
Bar Crest or Five
Foot Water Depth
if Bar Not
Present 0.31 0.30 0.3 0.2



RECOMMENDED INITIAL PROJECT CHARACTERISTICS AND EVOLUTION OF THE PLANFORM

Initial Planform

The most relevant parameters of the initial planform are the length, ,
the width, w, and the transition characteristics at the end of the project.
Using accepted procedures, the additional width, w, for various lengths and
nourishment quantities are presented in Table X. To provide a basis for
comparison, the average shoreline advancement associated with the 1985
nourishment was approximately 525 ft.


TABLE X
INITIAL PLANFORM CHARACTERISTICS


Project Additional Beach
Volume Placed Length Width
(yd3) (miles) (ft)

4 95 ft
2,000,000 6 60 ft

4 180 ft
4,000,000 6 120 ft

4 285 ft
6,000,000 6 180 ft

5,000,000 4.5 270 ft*
(with tapered ends)

*Recommended Plan










Planform Evolution

Considering the nourishment to occur over a beach segment encompassed by
FDNR Ranges 40 through 64 (4.5 miles), the recommended planform is presented
in Figure 12 and the anticipated evolution is presented in Figure 13. Figure
13a presents the planform at 2, 5 and 10 years for an otherwise stable shore-
line and Figure 13b presents the planform at the same time periods for the
more realistic case of a shoreline eroding at 5 ft. per year. In Figure 13,
the shoreline has been drawn straight for convenience rather than curved.
Also, the jetty at the northeastern end of Perdido Key (near DNR monument 67
is included).

Beach Profile

The planform characteristics presented in the preceding section and in
Table X have been based on the consideration that one cubic yard of sand along
one foot of beach length will cause a shoreline advancement of one foot.
Thus, this one cubic yard (27 cubic feet) is distributed such that it causes a
uniform profile advancement of one foot over a vertical portion of the profile
of 27 ft. The placement options include placing the material to a shallower
depth which means that the shoreline advancement must be greater. With this
placement strategy, the waves will ultimately redistribute the sand to greater
depths to yield the one foot shoreline advancement per cubic yard of sand per
unit length of beach. Figure 14 shows these two options and the recommended
profile shoreward of the equilibrated position of the initial shoreline. The
purpose of the lower berm (4 to 5 ft.) compared to the natural berm height
(approximately 6 ft.) is to allow the wind and water processes to exert their
respective shaping processes, thereby yielding a more natural profile.

BIOLOGICAL CONSIDERATIONS

No specific studies have been conducted to determine the effect of the
1985 beach nourishment on the biology of Perdido Key. However, monitoring
studies have been conducted of other projects and these results allow the
probable impact to be inferred.

The information below is drawn primarily from an excellent review by
Nelson (1985) of the effects of beach nourishment on the nearshore biota. The
primary focus will be on three common nearshore organisms: (1) Emerita
talpoida (mole crabs), (2) Donax (coquina clams), and (3) Ocypode (ghost
crabs).














0 5
1I I I I


Scale(mlles)


Project
Characterists


Recommended Nourishment
in Connection with Channel Dredging


Volume: 5 Million Cu. Yds.
Length: 4.5 Miles
Additional Beach Width: 270 Ft.


Figure 12. Location and Characteristics of Recommended Beach Nourishment.













30(
LU

z
I-
0
Q-n


Scale (miles)


40 50 60
DNR MONUMENT NUMBER

a) Calculated Evolution of Recommended Nourishment If Shoreline Were Stable.


West


Jetty


US
.o J3
*4 g


Initial


40 50 60 Jetty
DNR MONUMENT NUMBER

b) Calculated Evolution of Recommended Nourishment on a Shoreline Eroding at a Rate of
Five Feet Per Year.


Figure 13. Calculated Evolution of Recommended Nourishment Planform for Stable and Eroding
Beaches.


Initial











20




S1 0 Natural Berm Elevation 6 ft
+5ft +4ft
(. +4ft
z "
LU 280oft-
O
m 0

z
SRecommended
P Nourishment Profile
> 10 DNR Profile
W Measured October 31,1984



-20 -
I I I I I I I
0 300 600 900 1200 1500 1800

DISTANCE GULFWARD FROM DNR MONUMENT R-48 (ft)


Recommended Characteristics of Nourished Profile. Illustrated for DNR Monument No. 48


Figure 14.










Emerita Talpoida (Mole Crabs)


This organism is a filter feeder that burrows in the lower foreshore of
the beach and can be very abundant, although the densities tend to be very
irregular. The highly energetic swash zone appears to be the preferred
environment for E. Talpoida probably enhancing the food supply. Densities in
excess of 3,700 animals per square meter have been reported (Bowman, 1981).
The animals tend to be in greatest abundancies in Florida in December to
January.

E. Talpoida are very mobile and apparently have the capability to avoid
being buried by beach nourishing by leaving an area. In a project in which
956,000 m3 sand was placed on the Cape Hatteras beach, Hayden and Dolan (1974)
found no dead animals and they concluded that the affected areas recovered in
less than two weeks. The sand used in this nourishment project was quite
comparable to the native sand. A second project of similar quantity (904,000
m3) at Fort Macon, N.C., was monitored by Reilly and Bellis (1978, 1983);
however the sand was taken from dredged harbor sediments and was not
compatible in size characteristics. Additionally the sediment was from a
reducing enviornment. The monitoring indicated that the E. Talpoida
populations were nonexistent in the project area during material placement but
recolonized rapidly several months later during the spring recruitment
period. A delay of one month during the recruitment period was evident. The
summer after the commencement of nourishment (the preceding December), the
animal densities were the same on the nourished and control beaches. However,
there were significant differences in the size classes with the nourishment
containing exclusively juveniles. The investigators concluded that the adult
mole crabs in the vicinity of the nourished site were killed by turbidity and
that the juvenile animals had populated the area from the adjacent beaches.
Nelson (1985) has suggested that the liberated hydrogen sulfide in the
nourished sediments may also have contributed to the mortality of adult
animals.

In summary of the impact of beach nourishment on E. Talpoida, it is
concluded that these animals are very mobile and are able to vacate an area
unsuitable for their physiology. Moreover, with the return of favorable
conditions, they rapidly recolonize the area. If the material placed is
compatible with that originally on the beach, effects are of quite short










duration. If poor quality sediment is used, recovery is slower, but still
relatively rapid, probably due to the high motility of these animals and the
longshore currents on the beachface.


Donax (Coquina Clams)

This genus of bivalves has two species that have been reported to be
found in the Florida panhandle area. The documented range of Donax Variabilis
is from Virginia Beach, VA to Mississippi. Also Donax Texasianus has been
found in the Florida panhandle.

Most Donax Variabilis migrate up and down the beach with the tide,
presumably to be in the active swash zone where the high velocities ensure
ample quantities of moving water from which these filter feeders obtain
nourishment. However some studies have reported populations that do not
migrate with the tide. The life of Donax is generally 2-3 years with one or
two spawning periods per year. Primary spawning occurs in February and in
Florida a second spawning may occur in June. The peak seasonal abundance
tends to occur in June and July. Maximum densities of Donax Texasianus in
Panama City, Florida was 2,050 animals/m2

Few studies are available documenting the effects of beach nourishment on
Donax. Reilly and Bellis (1978, 1983), reporting on the effects of
nourishment on a North Carolina Beach found that following a December
nourishment event, Donax were not found in the nourished area until the
following July. These were young believed to be transported in by the
longshore currents and it was suggested that the adults were killed by burial
in the offshore area.


Ocypode Quadrata (Ghost Crab)

These animals burrow in the dry beach although they do lay their eggs in
the water. The older crabs tend to burrow higher on the beach than the young
animals. Their diet varies from dead plant and animal material to live Donax
and Emerita. Although seen frequently during the daytime, they are primarily
nocturnal.

Only the studies of Reilly and Bellis (1978, 1983) have evaluated the
effects of beach nourishment on ghost crab populations. Their limited data










indicated that the summer following nourishment, there was a 50% lower
population. Their interpretation was that, since the material was placed
below a level that would cause direct burial and since the crabs could
probably burrow up through placed sand, it is likely that the reduced
population was a result of emigration of the crabs due to a reduced food
supply.


Panama City Studies

Saloman (1976), Culter and Mahadevan (1982) and Saloman, et.al. (1982)
have reported on extensive biological studies in conjunction with the 1976
nourishment of some 300,000 cubic meters along the beaches of Panama City.

Saloman (1976) conducted a pre-nourishment baseline study in 1974-1975
and documented the effects of Hurricane Eloise (September, 1975) on the
biota. It was found that there was no decline in the abundance of intertidal
animals following the hurricane.

Culter and Mahadevan (1982) conducted studies in 1979-1980 to examine
long-term effects of the 1976 nourishment. They concluded


"No long-term adverse environmental effects as a
result of beach nourishment could be detected within
the nearshore zone of the Panama City beaches. There
were also no adverse or stressful conditions present
at the borrow sites."


Saloman, et.al. (1982) carried out a study analyzing data collected
between April 1976 and November 1977. The purpose of the study was to examine
short-term effects of offshore dredging on the benthic community. It was
concluded that there was an immediate decline in the benthic community;
however, the populations rapidly recovered and were virtually at pre-
construction levels within one year. It was noted that the borrow pits were
relatively small and no more than 5 m of sand (vertically) was removed from
each pit. The pits were located in water depths of 6 to 9 m. Initially the
pits filled with material finer than on the adjacent bottom; however, these
differences tended to diminish with further filling.










Summary Regarding Biological Effects of Beach Nourishment


Based on a comprehensive review of published information, Nelson (1985)
has concluded that the intertidal beach organisms are well adapted to this
high energy environment including times of significant erosion and accretion
and fluctuations in turbidity. During and immediately following storms,
massive erosion and deposition occur over segments of beaches long in
comparison to nourishment projects. Thus any adverse effects of beach
nourishment carried out with compatible sand tend to be short-lived as the
animals can either survive the event or are adapted to rapid lateral
recolonization. Nelson notes that although the available evidence indicates
minimal and short-lived biological effects, the present level of understanding
is such that biological monitoring programs are necessary to further document
the quantitative impacts of beach nourishment projects.


RECOMMENDATIONS

The following recommendations are made based on the results of this
study. In conjunction with the construction dredging of the Kitty Hawk
channel, it is recommended that up to a total of 5,000,000 cubic yards of
material be placed along a 4.5 mile segment along the eastern end of Perdido
Key as presented in Figure 12. Based on historical erosion data,
implementation of this recommendation would still fall short of restoring the
shoreline to the condition that would prevail if channel deepening projects
had not interfered with the natural processes. Based on Florida Department of
Natural Resources shoreline change data, this nourishment project would
reinstate the shoreline to its approximate condition some 20 years ago.
Moreover, this project should fill in and "arrest" to some extent the
shoreline erosional wave which is now moving to the west.

Soon after placement of the material, it is recommended that sea oats and
possibly other natural vegetation be planted to enhance dune formation and
early return to a more natural condition.

It is recommended that the above project be monitored to determine the
physical evolution and biological effects. A preliminary description of a
monitoring program to document the physical effects is presented in
Appendix I; it is recommended that the monitoring program continue for at
least five years.










If the project performs as expected with erosion of material in the
region placed and transport to and deposition in the beach segments adjacent
to the placement area, it is recommended that during future channel
maintenance, all beach quality sand up to 300,000 yd3/year be placed on the
beach. The most appropriate placement locations will be established as a
result of the monitoring efforts.


REFERENCES
Bowman, M.L. (1981) "The Relationship of Emerita Talpoida to Beach
Characteristics," M.S. Thesis, University of Virginia, Charlottesville,
Virginia, 106 pp.
Culter, J.K. and Mahadevan, S. (1982) "Long-Term Effects of Beach Nourishment
on the Benthic Fauna of Panama City Beach, Florida," Miscellaneous Report
No. 82-2, U.S. Army Corps of Engineers, Coastal Engineering Research
Center, Fort Belvoir, VA.
Dean, R.G. (1983) "Principles of Beach Nourishment," in Handbook of Coastal
Processes and Erosion, CRC Press, p. 217-231.
Hayden, B. and Dolan, R. (1974) "Impact of Beach Nourishment on Distribution
of Emerita Talpoida, the Common Mole Crab," Journal Waterways, Harbors
and Coastal Engineering Division, ASCE, Vol. 100, WW2, p. 123-132.
Nelson, W.G. (1985) "Guideline for Beach Restoration, Part I: Biological
Guidelines," Report No. 76, Florida Sea Grant College.
Rutgers University (Undated) "Measurements of Shoreline Positions Along
Perdido Key, 1985-1987".
Reilly, F.J. and Bellis, V.J. (1978) "A Study of the Ecological Impact of
Beach Nourishment with Dredged Materials on the Intertidal Zone,"
Institute for Coastal and Marine Resources, East Carolina University,
Technical Report No. 4.
Reilly, F.J. and Bellis, V.J. (1983) "The Ecological Impact of Beach
Nourishment with Dredged Materials on the Intertidal Zone at Bogue Banks,
North Carolina," U.S. Army Corps of Engineers, Coastal Engineering
Research Center, Miscellaneous Report No. 83-3.
Saloman, C.H. (1976) "The Benthic Fauna and Sediments of the Nearshore Zone
Off Panama City, Florida," Miscellaneous Report No. 76-10, U.S. Army
Corps of Engineers, Coastal Engineering Research Center, Fort Belvoir,
VA.










Saloman, C.H., Naughton, S.P. and Taylor, J.L. (1982) "Benthic Community
Response to Dredging Borrow Pits, Panama City Beach, Florida,"
Miscellaneous Report No. 82-3, U.S. Army Corps of Engineers, Coastal
Engineering Research Center, Fort Belvoir, VA.
Thompson Engineering Testing, Inc. (1987) "Grain Size Distribution and Calcium
Carbonate Analyses of Sediment Samples," Contract N62467-85-C-0593,
Amendment/Modification No. P00009, Mobile, Alabama.










Summary Regarding Biological Effects of Beach Nourishment


Based on a comprehensive review of published information, Nelson (1985)
has concluded that the intertidal beach organisms are well adapted to this
high energy environment including times of significant erosion and accretion
and fluctuations in turbidity. During and immediately following storms,
massive erosion and deposition occur over segments of beaches long in
comparison to nourishment projects. Thus any adverse effects of beach
nourishment carried out with compatible sand tend to be short-lived as the
animals can either survive the event or are adapted to rapid lateral
recolonization. Nelson notes that although the available evidence indicates
minimal and short-lived biological effects, the present level of understanding
is such that biological monitoring programs are necessary to further document
the quantitative impacts of beach nourishment projects.


RECOMMENDATIONS

The following recommendations are made based on the results of this
study. In conjunction with the construction dredging of the Kitty Hawk
channel, it is recommended that up to a total of 5,000,000 cubic yards of
material be placed along a 4.5 mile segment along the eastern end of Perdido
Key as presented in Figure 12. Based on historical erosion data,
implementation of this recommendation would still fall short of restoring the
shoreline to the condition that would prevail if channel deepening projects
had not interfered with the natural processes. Based on Florida Department of
Natural Resources shoreline change data, this nourishment project would
reinstate the shoreline to its approximate condition some 20 years ago.
Moreover, this project should fill in and "arrest" to some extent the
shoreline erosional wave which is now moving to the west.

Soon after placement of the material, it is recommended that sea oats and
possibly other natural vegetation be planted to enhance dune formation and
early return to a more natural condition.

It is recommended that the above project be monitored to determine the
physical evolution and biological effects. A preliminary description of a
monitoring program to document the physical effects is presented in
Appendix I; it is recommended that the monitoring program continue for at
least five years.










APPENDIX I
PRELIMINARY MONITORING PROGRAM TO QUANTIFY
PHYSICAL EFFECTS OF BEACH NOURISHMENT ON PERDIDO KEY


INTRODUCTION

The purpose of the monitoring program described below is to establish the
physical effects of beach nourishment on Perdido Key. The results of this
program will serve to quantify the performance of the nourishment project and
to establish optimum quantities and location of material placement in future
maintenance programs. The results will be used also to evaluate/improve
methods of predicting performance of such projects, an objective of importance
to both the Corps of Engineers and the National Park Service. Finally, of
special importance will be the evolution of the upper portions of the beach
profile (presented in Figure 14) toward more natural vegetation, profile and
grain size characteristics than would occur otherwise. The biological
monitoring plan will be developed and submitted separately.


MONITORING PROGRAM ORGANIZATION

In accordance with the objectives of the monitoring to be able to
document and predict the performance of the nourishment project, the program
is organized into Past, Present and Future components.


Past

This component comprises a historical study to document the changes that
have occurred to Perdido Key and the modifications of the large scale
"forces", predominantly dredging at the Pensacola Channel and the occurrence
of major storms. The effects of recent storms (Camille, 1969; Frederic, 1979;
Elena, 1985) have been documented rather well and will serve to assist in
quantifying shoreline effects that should be associated with earlier major
storms for which the shoreline effects have not been documented.


Present

This component would concentrate on documenting pre-nourishment
conditions and the effects of the nourishment project.










Future

Results from the Past and Present programs will be combined to predict
evolution of the nourishment project farther into the future. Also the
monitoring results will serve as a basis for evaluating and refining present
prediction calculation methodology. The revised methodology will be used to
evaluate various scenarios for maintenance material placement and through this
process, recommendations developed.


PROGRAM DURATION AND ELEMENTS

The recommended duration of the recommended monitoring program is five
years with one complete set of measurements carried out prior to commencement
of the nourishment project.

The recommended monitoring elements are


(1) Beach and Offshore Profiles All profiles would be carried out at DNR
monument locations. Profiles would be taken at a total of 31 monuments
with:


5 Profiles, Monuments 27-35, Alternate Monuments
10 Profiles, Monuments 36-45, Every Monument
6 Profiles, Monuments 47-57, Alternate Monuments
10 Profiles, Monuments 58-67, Every Monument


These profiles would be taken twice yearly (spring and fall) and after
major storms, extending offshore 1,000 m or to the 8 m contour on the
Gulf side, across the island to wading depth on the bay side. The
bayside profiles need only be conducted during the first survey period
and after storms which affect the dunes and cause washover deposits.
The locations of the profiles are presented in Figure I-1.


2. Sand Sample Collection Samples will be collected in conjunction with
the profiling described above. The samples shall be taken at
representative positions of the profile including: dune, berm, beach
face, depths of 1 m, 2 m, 5 m, 8 m, 10 m on the Gulf side and at the
shoreline and at 1 m and 2 m on the bay side. Samples will be taken

with each set of profiles.















4,


0 1 2
I I I S mil )
Scale(miles)


R-55


Approximate
Westerly Park
Boundary


I I I I ii I I I
I I I I I I I I I

Possible Location of
Directional Wave Gage


I I I


I Iill i Z
I i i
I'
Recommended Beach
Nourishment


NOTE:
R-40 is Florida Department of Natural
Resources Monumented "Range 40"


Figure I-1. Recommended 31 Profile Locations and Location of Directional Wave Gage


R-30










3. Aerial Photographs Black and white and color photography shall be
taken in conjunction with the fall profiling and provided at scales of
1:12,000 (Color) and 1:2400 (Black and White).


4. Directional Wave Gage It is recommended that a directional wave gage
be located in a water depth of approximately 10 m, see Figure I-1.


5. Weather Station A weather station should be installed. The primary
components of the station are: rain gage, recording anemometer (wind
speed and direction) and recording barometric pressure.


6. Ground Photographs Approximately 40 locations of special interest
relative to vegetation growth or shoreline change will be identified
initially and will be photographed on a bimonthly basis.


PROJECT COST

It is envisioned that the physical component of the monitoring program as
described herein would cost approximately $200,000 per year for a total of
$1,000,000. It is planned that where advantageous to understanding and
interpretation, the biological and physical field collection components will
be coordinated.










APPENDIX II
GOVERNING EQUATIONS FOR BEACH PLANFORM EVOLUTION


It can be shown that beach profile evolution along a straight shoreline
is approximately in accord with the following linear partial differential
equation:


-y = B -92 (II-1)
at x2
ax

in which y is the shore-perpendicular distance from a baseline to a particular
contour (which in this case will be mean sea level), x is the alongshore
distance, t is time and B is an "activity" coefficient related to breaking or
shallow water conditions as:

Breaking Wave K Hb5/2gK cos(B-ab
Conditions: B = (11-2)
Conditions: B =-8 (S 1) (1 p) (h + G) (II-2)


2
Deep Water KH gT cos(B a )
Conditions: B = 32w (S- 1) (1 p) (h+ G) (1-3)


in which K is a sediment transport coefficient, usually taken as 0.77, H and T
represent the wave height and period, respectively, g is the gravitational
constant, K is the spilling breaker constant (= 0.8), S is the ratio of
sediment density to water density, p is the porosity, (h* + G) is the vertical
dimension of the portion of the profile partipating in the profile response, a
is the azimuth of the outward shore normal, a is the azimuth of the direction
from which the waves originate and the subscripts "o" and "b" denote
conditions at deepwater and breaking, respectively.

Considering a nourishment project of uniform width, w, over a length, L,
forming a rectangular planform, it can be shown that the solution to Eq.
(II-1) is

w L 2x L 2x
y(x,t) = {erf[--- ( + i)] erf[-- (---- ]}11-4)
2 4/Bt L 4/1

in which "erf" is a mathematical function called the "error function".










The fraction, F, of the fill removed from the region placed due to
longshore sediment transport can be shown to be approximated for early time,
t, by


F = (11-5)
rw L

in which t is the time during which the fill is lost.

Considering that 35% of the fill was transported out of the area placed
in a period of 10 months (September, 1985 to July, 1987, Table VI), an
effective breaking wave height, Hb, can be determined as

2 F
B = --F
4t

ST (4000)2(.35)2 2
4 (685 x 24 x 3600) 0026 ft

and, from Eq. (1-2)

0.4
8B(S 1)(1 p) (h,+ G) 4
Hb [ "]
b K/g/ cos(B ab)


0.4
H = [8(.026)(1.65)(.65)(27)] = 1.1 ft
0.77 f32.2/0.78 1


in which the approximation cos(B ab) = 1.0 has been made.


















51




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