Citation
Midtown beach nourishment project in Palm Beach, Florida

Material Information

Title:
Midtown beach nourishment project in Palm Beach, Florida October 1995 to August 1996
Series Title:
UFLCOEL-97001
Alternate title:
Monitoring report
Creator:
Dean, Robert G ( Robert George ), 1930-
University of Florida -- Coastal and Oceanographic Engineering Dept
Place of Publication:
Gainesville Fla
Publisher:
Coastal & Oceanographic Engineering Dept., University of Florida
Publication Date:
Language:
English
Physical Description:
v, 8, 48 leaves : ill. ; 28 cm.

Subjects

Subjects / Keywords:
Beach nourishment -- Florida -- Palm Beach ( lcsh )
Shore protection -- Florida -- Palm Beach ( lcsh )
Genre:
non-fiction ( marcgt )

Notes

General Note:
"February 24, 1997."
Statement of Responsibility:
prepared for town of Palm Beach ; prepared by Robert G. Dean.

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
The University of Florida George A. Smathers Libraries respect the intellectual property rights of others and do not claim any copyright interest in this item. This item may be protected by copyright but is made available here under a claim of fair use (17 U.S.C. §107) for non-profit research and educational purposes. Users of this work have responsibility for determining copyright status prior to reusing, publishing or reproducing this item for purposes other than what is allowed by fair use or other copyright exemptions. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder. The Smathers Libraries would like to learn more about this item and invite individuals or organizations to contact Digital Services (UFDC@uflib.ufl.edu) with any additional information they can provide.
Resource Identifier:
36846219 ( OCLC )

Full Text
UFL/COEL-98/012

MONITORING REPORT MIDTOWN BEACH NOURISHMENT PROJECT IN PALM BEACH, FLORIDA October 1995 to April 1998 by
Robert G. Dean

July 11, 1998
Prepared for: Town of Palm Beach West Palm Beach, Florida 33401




MONITORING REPORT

MIDTOWN BEACH NOURISHMENT PROJECT IN PALM BEACH, FLORIDA
October 1995 to April 1998
July 11, 1998
Prepared For:
Town of Palm Beach Suite A
951 Old Okeechobee Road
West Palm Beach, Florida 33401
Prepared by:
Robert G. Dean
Department of Coastal and Oceanographic Engineering
University of Florida
Gainesville, Florida 32611




TABLE OF CONTENTS
INTR O D U CTIO N .......................................................... I
R E SU L T S ................................................................ 3
B each Profiles ........................................................ 3
Longshore, Distributions of Shoreline Change and Volume Density ................ 12
Changes in Total Volumes and Plan Areas .................................. 12
Changes in Shoreline Position and Volume Density Along the North Beach Area ..... 12 Borrow Area D efinition ................................................ 18
SUMMARY AND CONCLUSIONS .......................................... 21
M idtown Nourishment Area ............................................. 21
N orth Beach Area .................................................... 21
B orrow A rea ........................................................ 21
RE FERE N CE S ........................................................... 21




LIST OF FIGURES

FIGURE PAGE
1 Location Map of Project Area Showing Borrow and Nourishment Areas. (Adapted
from ATM Drawing)................................................. 2
2 Profiles at DNR Monument R-96D Located Approximately One-Quarter of
Nourished Length From North End of Project ...............................4
3 Profiles at DNR Monument R-97CI126 Located Approximately Midway Along
Nourished Project................................................... 5
4 Profiles at DNR Monument R-98G Located Approximately Three Quarters of
Nourished Length From North End of Project ...............................6
5 Profile at DNR Monument R-78.5 Located Approximately 3,000 Feet South of South
Jetty, Through Borrow Area........................................... 7
6 Profiles at DNR Monument R-79 Located Approximately 3,500 Feet South of South
Jetty, Through Borrow Area........................................... 8
7 Profile at DNR Monument R-79.5 Located Approximately 4,000 Feet South of South
Jetty, Through Borrow Area........................................... 9
8 Profiles at DNR Monument R-80 Located Approximately 4,500 Feet South of South
Jetty, Through Borrow Area.......................................... 10
9 Profile at DNR Monument R-80.5 Located Approximately 5,000 Feet South of South
Jetty, Immediately South of Borrow Area .................................11
10 NGVD Shoreline Changes Due to Nourishment Project .......................13
11 Volume Changes Due to Nourishment Project ..............................14
12 Percentage Total Volume and Plan Area Remaining in Placement Area ............ 15
13 Cumulative Volumes of Sand Added by Sand Bypassing Plant ...................16
14 Shoreline Changes Due to Nourishment Project in the North Beach Area ........... 17
15 Volume Changes Due to Nourishment Project in the North Beach Area ............ 19
16 Depth Contours (feet, NGVD) in Vicinity of Borrow Area ..................... 20




LIST OF TABLES
TABLE PAGE
I Dates of M onitoring Surveys ............................................. 3
2 Changes in Total Volumes and Plan Areas .................................. 18




MONITORING REPORT

MIDTOWN BEACH NOURISHMENT PROJECT IN PALM BEACH, FLORIDA
October 1995 to April 1998
INTRODUCTION
During the period October 18, 1995 to December 10, 1995, approximately 880,000 cubic yards of sand were dredged from a borrow area extending from approximately 2,000 feet south to 4,800 feet south of the south jetty at Lake Worth Entrance and placed along portions of the Midtown Beach section in the Town of Palm Beach, Florida. As shown in Figure 1, the cross-shore dimensions of the borrow area varied from 1,600 feet at its northern end to 2,500 feet at its southern end. The original depths at the borrow area site varied from 25 to 35 feet and the maximum dredged depths were approximately 40 feet deep. The dredged sand was placed along the Midtown Beach as nourishment extending from via Bethesda at the north end to via Marina at the south end, a distance of approximately 5,400 feet. To provide stability to the nourishment project, eleven groins were constructed. The locations of these groins are shown in Figure 1 along with the borrow area and the approximate planforin of the nourished beach. Sea Systems, Inc has conducted a pre-nourishment survey and five post-nourishment surveys to document the performance of the project. The purpose of this report is to present the results of an analysis of these six surveys.
The dates of the surveys are presented in Table 1. Although the placement of material was completed in December 1995, as can be seen from Table 1, the first post-nourishment survey was not completed until April 9, 1996 due to the activities related to groin construction. During the period between completion of nourishment and the first post-nourishment survey, a significant northeaster occurred (March 8-10, 1996) which undoubtedly caused the transport of some sand from the nourished beach. Thus, since the first post-nourishment survey post-dated the March storm, the first post-nourishment survey does not reflect the total amount of sand placed.
This report updates the monitoring results through the April 1998 survey. Additionally, this report presents an analysis of the shoreline and volume changes at the north end of the study area in the vicinity of the borrow area and presents data relating to the borrow area, which were obtained in part, from three additional survey lines that were conducted in the April 1998 survey for this purpose. Previous monitoring results, presented in Dean (1997a, 1997b, and 1997c), provide details on aspects of the nourishment project not addressed in this report.




Borrow Area

R-a7 OCEAN I I
R-88 0 1.0
-89 Scale (Miles)
1-90
-92
-93 Typical Groin, One of Eleven
-94 Numbered From S I at the North to
S I1 at the Southern End
_Project Site
Figure 1. Location Map of Project Area Showing Borrow and Nourishment Areas.
(Adapted from ATM Drawing).




Table 1
Dates of Monitoring Surveys

I Survey Number J Type of Survey IDates
1 Pre-Nourishment October 13-21, 1995
2 Post-Nourishment April 1-9, 1996
3 Post-Nourishment August 12-25, 1996
4 Post-Nourishment March 31 to April 8, 1997
5 Post-Nourishment August 27-30, 1997
6 Post-Nourishment April 22-27, 1998
RESULTS
The results are presented in various forms, including examples of beach profiles, longshore distribution of additional beach width as a function of time, longshore distribution of additional volume as a function of time, and total additional areas and volumes as functions of time.
Beach Profiles
Figures 2, 3 and 4 present examples of beach profiles in the nourishment area. Figures 2, 3 and 4 are located at approximately one-quarter, one-half and three quarters of the distance from the northerly to the southerly limits of the beach nourishment project, respectively. In order to maintain the number of surveys presented reasonable, only the pre-nourishment survey (October 1995), the first post-nourishment survey (April 1996), the third post-nourishment survey (April 1997) and the most recent survey (April 1998) are presented on these plots. It is seen from inspection of these figures that the northern most profile has been eroded the most, whereas the profiles located midway and near the southern end of the Project have experienced less erosion. This is consistent with the southerly direction of net longshore sediment transport.
Figures 5, 6, 7, 8, and 9 are profiles in the vicinity of the borrow area. For those profiles that have been surveyed previously (Profiles R-78 and R-79), the same survey dates are presented as for the profiles in the nourishment area. Profiles R-78.5, R-79.5 and R-80.5 were surveyed for the first time during the April 1998 survey to provide a better definition of the borrow area. Figure 5, representing the profiles at DNR Monument R-78.5 is located approximately 3,000 feet south of the south jetty and is the most northerly profile which indicates the presence of the borrow area. Figures 6 and 8 document that there has been only minor filling of the borrow area since the April 1996 survey.




0
z
0
Co
0
a,
w

20 10
0
-10
-20
-30
-40

October 1995 ..................... ..........................Apri1996
- - - . .A p ril 1 9 9 7
----- April 1998 ," :. .. ........ .... . . . .. ...... .. ... .. .. .... .. .... ... .. . .. . ... ...... . . .. . . .. . ...

1000

2000

3000

Seaward Distance from Monument (ft)
Figure 2. Profiles at DNR Monument R-96D Located Approximately
One-Quarter of Nourished Length From North End of Project

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




_ 20
October 1995
o .... April 1996
>10 ...............................................................--- April 1997
(19............. ------------------------------------------- April------1998 --Co
a
40 2
W -30
0 1000 2000 3000
Seaward Distance from Monument (ft)
Figure 3. Profiles at DNR Monument R-970126 Located
Approximately Midway Along Nourished Project




_20
October 1995
10 ................ ......................... ......... April 1997
----- April 1998
z K . ...................................................
0
C
0
0 1000 2000 3000
Seaward Distance from Monument (ft)
Figure 4. Profiles at DNR Monument R-98G Located Approximately
Three Quarters of Nourished Length From North End of Project




20

20
0 1 0 ............................... ........................... .
I

------- April 1998

-Si

Z 0 ... .. ... ... ......................................................................................
2
0%%
% %
> 1 .. . ............. --------------................................................................
> -10n...............'I
n ," 2 0 .... .... ... .... .... .... ...i ...:..-- .. ... ....................................................
4 3 ........ . . .. . . ....................................4 ...................................
W. -40,
0 1000 2000 3000
Seaward Distance from Monument (ft)
Figure 5. Profile at DNR Monument R-78.5 Located Approximately
3,000 feet South of South Jetty, Through Borrow Area




20
October 1995
o10 ------- ------............................... ......... April 1996
> ------- April 1997
0 '11.....................................
Co
0
4. -30 .............................. ----........%:.... .................
CU.
0 1000 2000 3000
Seaward Distance from Monument (ft)
Figure 6. Profiles at DNR Monument R-79 Located Approximately
3,500 feet South of South Jetty, Through Borrow Area




20
April 1998
o 10 '0
0)4
> 1 l . . .... ...... . . . . . . . . . .. . . . . . . . . .
CU
a)
WoC -20 ......... .........
0 1
W -4 -%0 1000 2000 3000
Seaward Distance from Monument (ft)
Figure 7. Profile at DNR Monument R-79.5 Located Approximately 4,000 feet South of South Jetty, Through Borrow Area




20

-
October 1995
1 0 ................................. .................................. ......... A pril 1996
>, X ------- April 1997
(D- -- -- ------- April 1998
Z 0 .............................. .................................. .................................
A..
-10 S..
Ca
a) -2 0. ... ...-.. ... ...:..,..... ..:
0 -2 0 ........ .... .... .... ...
U)t
"- .. .. . ..
WU -401'' :'''"
0 1000 2000 3000
Seaward Distance from Monument (ft)
Figure 8. Profiles at DNR Monument R-80 Located Approximately 4,500 feet South of South Jetty, Through Borrow Area




_20
April 1998
. . . . . . . . . . . . . . . . .
00
.. .. . .. ...a.. .. . -1 . .
CU -30........................... ..........................
W -40
0 1000 2000 3000
Seaward Distance from Monument (ft)
Figure 9. Profile at DNR Monument R-80.5 Located Approximately 5,000 feet South of South Jetty, Immediately South of Borrow Area




Figure 9, which presents a survey of a profile located some 5,000 feet south of the south jetty, shows only a minor indication of the borrow area. More detailed plots of profiles R-78 and R-79 through the borrow area are presented in Dean, 1997c.
Longshore Distributions of Shoreline Change and Volume Density
Figure 10 presents the longshore distribution of shoreline change within the nourishment area. There was considerable decrease in beach width during the last year, although, on average, there is still approximately 85 feet of additional beach width as a result of the beach nourishment project. Part of the decrease in beach width will be shown to be due to sand being transported offshore rather than due to a volume loss. This seaward transport is a normal process due to steep winter waves and much of this sand is expected to return with the occurrence of the milder summer waves. Figure I I presents the additional volume density along the Project area. As noted, there is a significantly smaller volume decrease than beach width supporting the statement of seaward sediment transport. There is still an average of approximately 120 cubic yards per foot of beach of additional sand volume within the project area as a result of the nourishment project.
Changes in Total Volumes and Plan Areas
Table 2 presents the total changes in volumes and plan areas from the pre-nourishment survey to the five post-nourishment surveys. The statements regarding the greater changes in beach width are evident in the reduction in total plan area compared to the relative small decrease in total volume during the last survey period.
Figure 12 presents the history of percentage change in total volume and plan area. It is seen that as of April 1998, there is approximately 53% of the placed plan area remaining and 7 1 % of the volume placed remaining in the placement area. Although the placed plan area was not determined (prior to the March 1996 storm) it was estimated to be 20.5 acres.
Changes in Shoreline Position and Volume Density Along the North Beach Area
Since initiation of the Midtown Beach Nourishment Project, sand has been transferred by the sand transfer plant located on the north jetty of Lake Worth Entrance from the north to the south side of the Entrance. Figure 13 shows the cumulative volumes placed. Sand transfer commenced in May 1996 with the refurbished transfer plant and discharge line. As of April 1998, approximately 370,000 cubic yards of sand had been transferred.
Figure 14 shows the shoreline changes along the North Beach relative to the first survey of shoreline positions in October 1995. As a result of the transfer of significant volumes of sand to the North Beach Area, all of the post-nourishment surveys except the first survey in April 1996 document an advanced shoreline over the first 3,400 feet south of the entrance relative to the October 1995 position.




- -

300

1000

2000

3000

4000

5000

6000

7000

8000

Distance South of Monument R-94E (ft)
Figure 10. NGVD Shoreline Changes Due to Nourishment Project

200
100
0

0
-D
I.
0
L
03

-100

April1996
-------- April 1997
------- April 1998
...... .... .. . ... .. .. . . --,, O ) C/) C/C) C/) C) U)
: j Lmt
Project Limits
I
I i I I I. .




300 Ari 199
April 1996
----- April 1997
- April 1998
Vo X' Cn q-j LO(0 1,--0*
-
0 1000 2000 3000 4000 5000 6000 7000 8000
Distance South of Monument R-94E (ft) Figure 11. Volume Changes Due to Nourishment Project




c100
8 0 -- - - - -I-- - -- .. . . . . . . Volum es
........ Plan Areas
50 ........'.......;
C
U 4 0 1.. . . . . . 2D 3D
Years~ ~~,* AfeCopltoDfNorsmn
Figure..... 12 Percentage... Total.... Volume... an lnAe
30 ~ ~ Rminn in------- Placement. Area W




co0.5
0
CD)
0
~0
CU
EI
=0.0 o 0 1 2 3
Years After October 1995
Figure 13. Cumulative Volumes of Sand Added
by Sand Bypassing Plant




LO 200~ April 1996
....... August 1996
U) .April 1997
0l August 1997
100 *April 1998
U) 0 %
C
a)
00
a)
-C
Distance South of Monument R-77 (ft)
Figure 14. Shoreline Changes Due to Nourishment Project
in The North Beach Area




Table 2
Changes in Total Volumes and Plan Areas

Period J Change in Volume (yd') Change in Plan Area (Ars
October 1995 to April 1996 +794,900' (+759,900) +18.4' (+17.9)
October 1995 to August 1996 +790,400' (+754,800) +18.4' (+17.7)
October 1995 to April 1997 +684,100' (+648,200) +14.4' (+14.0)
October 1995 to August 1997 +672,400' (+640,100) +14.4' (+14.0)
October 1995 to April 1998 +657,800' (+640,100) +11.1' (+10.6)
*Notes: These changes are from Monument R-941 to R-1I00C, a longshore distance of 6, 100 feet.
The numbers in parentheses represent the changes over the 5,400 feet constructed
Project length.
Figure 15 presents the volumetric distribution of volume changes per unit beach length along the North Beach Area. With the exception of the first two post-nourishment surveys, the volume changes over the northernmost 3,000 feet are positive. The total volume change documented as of the April 1998 survey is +120,000 cubic yards which suggests that the remainder of the bypassed sand (250,000 cubic yards) has been transported south beyond the monitoring limits of the North Beach Area.
Borrow Area Definition
As noted previously, the borrow area extends from approximately 2,000 feet to 4,800 feet south from the south jetty. The actual borrow area depression was defined through a combination of inspection of the five post-nourishment profiles in the vicinity of the borrow area and examination of a SHOALS survey conducted on February 20, 1997 which encompasses the borrow area. Figure 16 presents the borrow area contours obtained by this approach.




CO
v100
Lo 80
0)
60
Q) 40
a20 0
o20
0
E 0
&- -20
UL
Q) -40
CM)
CO-60
0 -80
a)
E-100
"5 >3

............................................. April 1996
......... August 1996
......... .. -- ... .-- .. ............ ................ .. . . A p ril 1 9 7. .
N Apri1997
------- August 1997
"-"- ".:.-.- ,.. -- April 1998
-- -....................... .......April1998
..."... . ;- -- -- .
. . . . . .. ..... ,
.. .. ..
- ---- ----- -- --- ... .. ..... ... ..
. . .... . ..". .: . .. . . . . . . . .
--- -- ---- -S. -- -
,- . . ....... .
- - .-- - - - --.. . -.. .. . . ..-- - . . .. . . . . .. . . . . . . ... . . . . . . ..
. .. ...... ...... ...... ............ .... .... :.. . ........... . .. . . .. .. ...... .... I .. .. .... .... .. .. .....

1000 2000 3000 4000
Distance South -of Monument R-77 (ft)
Figure 15. Volume Changes Due to Nourishment Project
in The North Beach Area

5000




LAKa Wo aIA ENTRAmcE

Uj
to
o
'3
OC

--8&3 5ooN
-s
'II
g o.
u 16921(i A
OF
Figure 16;. Depth Contours (feet, NGVD) in Vicinity of Borrow Area




SUMMARY AND CONCLUSIONS

This report has presented an analysis of the changes occurring in the monitoring area associated with the Midtown Beach Nourishment Project. Nourishment of this project commenced 2.5 years and was completed 2.3 years prior to the most recent survey in April 1998. Results documenting the changes in the North Beach Area have been presented including the cumulative volumes added to the beach through sand transfer, the additional beach width and the additional volumes documented on the beach. Finally, the contours associated with the borrow area have been presented.
Midtown Nourishment Area
Based on the five post-nourishment surveys representing approximately 2.5 years since nourishment, the Midtown Beach project has performed quite well. Of the 880,000 cubic yards placed, there are some 640,100 cubic yards remaining in the placement area. As shown from Figure 12, the decreases were small even during the last winter storms. The additional plan area has decreased significantly from the last survey, from 14.0 acres to 10.6 acres relative to the pre-nourishment condition when there was almost no beach. Much of the decrease in plan area is expected to return during the next monitoring period as a result of the milder wave action. As of the April 1998 survey, approximately 71% of the volume placed remained in the monitoring area and 53% of the plan area was present.
North Beach Area
The shoreline and volume changes along the North Beach Area are significantly improved relative to the October 1995 survey which preceded the nourishment. This is due to the transfer of approximately 370,000 cubic yards of sand to the North Beach Area.
Borrow Area
The characteristics of the excavated borrow area are presented in Figure 16.
REFERENCES
Dean, R. G. (1997a) "Midtown Beach Nourishment Project in Palm Beach, Florida: October 1995 to August 1996", University of Florida, Department of Coastal and Oceanographic Engineering Department, Report No. UFL/COEL-97/00 1.
Dean, R. G. (1997b) "Midtown Beach Nourishment Project in Palm Beach, Florida: October 1995 to April 1997", University of Florida, Department of Coastal and Oceanographic Engineering Department, Report No. UFL/COEL-97/0 13.
Dean, R. G. (1997c) "Midtown Beach Nourishment Project in Palm Beach, Florida: October 1995 to August 1997", University of Florida, Department of Coastal and Oceanographic Engineering Department, Report No. UFL/COEL-97/0 15.