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UFL/COEL-98/019
MONITORING REPORT
MIDTOWN BEACH NOURISHMENT PROJECT IN
PALM BEACH, FLORIDA
October 1995 to August 1998
by
Robert G. Dean
December 15, 1998
Prepared for:
Town of Palm Beach
Palm Beach, Florida 33480
MONITORING REPORT
MIDTOWN BEACH NOURISHMENT PROJECT
IN PALM BEACH, FLORIDA
October 1995 to August 1998
December 15, 1998
Prepared For:
Town of Palm Beach
Post Office Box 2029
360 South County Road
Palm Beach, Florida 33480
Prepared by:
Robert G. Dean
Department of Coastal and Oceanographic Engineering
University of Florida
Gainesville, Florida 32611
TABLE OF CONTENTS
INTRODUCTION ..........................................................
RESULTS ............................................ .......................3
Beach Profiles ................................ .......................3
Longshore Distributions of Shoreline Change and Volume Density ................. 3
Changes in Total Volumes and Plan Areas ................................... 8
Change in Volume Along the North Beach Area .............................. 11
SUMMARY AND CONCLUSIONS ........................................... 11
REFERENCES ............................................................. 11
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-97C126 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 NGVD Shoreline Changes Due to Nourishment Project ........................ 7
6 Volume Changes Due to Nourishment Project .............................. 9
7 Percentage Total Volume and Plan Area Remaining in Placement Area ............ 10
LIST OF TABLES
TABLE PAGE
1 Dates of Monitoring Surveys .............................................. 3
2 Changes in Total Volumes and Plan Areas ................................. 8
MONITORING REPORT
MIDTOWN BEACH NOURISHMENT PROJECT
IN PALM BEACH, FLORIDA
October 1995 to August 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 planform of the nourished beach. Sea Systems, Inc has conducted a pre-nourishment
survey and six 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 seven 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 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 August 1998 survey. Previous monitoring
results, presented in Dean (1997a, 1997b, 1997c and 1998a), provide details on aspects of the
nourishment project not addressed in the present report.
Borrow Area
R-87 OCEAN I I
-88 0 1.0
-89 Scale (Miles)
S-90
-91
-92
S-93 Typical Groin, One of Eleven
c r-9, Numbered From Sl at the North to
S 11 at the Southern End
R- Project Site
-- 00
i -^98
Figure 1. Location Map of Project Area Showing Borrow and Nourishment Areas.
(Adapted from ATM Drawing).
Table 1
Dates of Monitoring Surveys
Survey Number Type of Survey Dates
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
7 Post-Nourishment August 17-31, 1998
RESULTS
The results are presented in various forms, including samples of beach profiles, longshore
distribution of additional beach width for several surveys, longshore distribution of additional
volume for several times, and total additional areas and volumes as functions of time. In addition,
the volume change over the latest intersurvey period in the north beach monitored area is reported.
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 second post-nourishment survey (August 1996), the
fourth post-nourishment survey (August 1997) and the most recent survey (August 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.
Longshore Distributions of Shoreline Change and Volume Density
Figure 5 presents the longshore distribution of shoreline change within the nourishment area for the
first post-nourishment survey (April 1996) and for all subsequent August surveys. There was
20
^ 0 i-----------------I---
SOctober 1995
1 0 -- - - ------ ---- ---- ........ A pril 1996
> -------.- August 1996
. ------- August 1997
Z .. --- August 1998
-- -- -- -- - .. .. .. .. .. .. .. .. .. .
0
-10
>K -2 0 - -- - -- -- - -- --....... \...... .r-: . . ............ : ..................................
.0 -
..3..................... .. .. ...........................
"U -30 .----------------------------------- ------------ -----------------
W -40
0 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
10 ...... ....- .- ---..i- --.-----..... .........------- October 1997 -
--- October 1998
1
.. . . . . . .
S-20 -------------- -
-30
0 1000 2000 3000
Seaward Distance from Monument (ft)
Figure 3. Profiles at DNR Monument R-97C126 Located
Approximately Midway Along Nourished Project
20
SOctober 1995
> 10 .............. .............. ................ ... April1996
10 --- ----- -- .. ... .. April 1996
.-------- August 1996
------- August 1997
0 ................................... ......... .............. - August 1998
-10 "..%. A----------------
r0)
-10
O -20
il-3 0 ---** -* - --- ----------- - ----- -I ------------ -- - --------- .. .. .. .. .. .. .. .
-30
-40
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
300
/
- -- -- -- -- - -
.~~ ~ ...... .
V
r-
c-
C)
C3
0
r-c
I
I I
1000
2000
3000
I I
4000
5000
6000
Distance South of Monument R-94E (ft)
Figure 5. NGVD Shoreline Changes Due to Nourishment Project
200
100
0
Project Limits
April 1996
August 1996
\ugust 1997
\ugust1998
-100
LI
7000
8000
-"
------ /
./--/
* > 4
7
considerable decrease in beach width during the last year, although, on average, there is still
approximately 90 feet of additional beach width in the Project area 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. Figure 6 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 115 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
six 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 7 presents the history of percentage change in total volume and plan area. It is seen that as
of August 1998, there is approximately 55% of the placed plan area remaining and 67% 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. As noted from Figure 7, there was
a small increase in the plan area between April 1998 and August 1998. This recovery in plan area
was anticipated in the previous report.
Table 2
Changes in Total Volumes and Plan Areas
Period Change in Volume (yd3) Change in Plan Area (Acres)
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* (+620,500) +11.1* (+10.6)
October 1995 to August 1998 +628,600* (+593,300) +11.8* (+11.2)
*Notes: These changes are from Monument R-94I to R-100C, a longshore distance of 6,100 feet.
The numbers in parentheses represent the changes over the 5,400 feet constructed
Project length.
300
April 1996
August 1996
------- August 1997
.200 i ... i.....--- ---- ~ August 1998 -
Ca 10 0 - -- ---
-o 3 O: D 1 ,- o0
E
o 0 ; Project Limits
-1001
0 1000 2000 3000 4000 5000 6000 7000 8000
Distance South of Monument R-94E (ft)
Figure 6. Volume Changes Due to Nourishment Project
g1 100
S................... .Volum es
E. ......... Plan Areas
80 ----------
S0 :......... .. .-. ..................... ....-'::: ............ ..-
0) -" IA
U 70 I I-- -
E 2 0 : .......... = ..... ... .... ....... .... ...... ......... .. ....... ....
0 60 -
S 1 0 . . ..... ....... ... ... ...... ... .... .. .. . .. .. ....-. ..... .. .. ...
0: 5 0 --- - - - - - -
-- - -- - - Q \----------------------------------------------------------
4 0 -- - - -
S 0 1 2 3
Years After Completion of Nourishment
Figure 7. Percentage Total Volume and Plan Area
Remaining in Placement Area
1 0 -- - - -
Remaining in Placement Area
Change in Volume Along the North Beach Area
Since initiation of the Midtown Beach Nourishment Project, sand has been deposited by the sand
transfer plant located on the north jetty of Lake Worth Entrance from the north to the south side of
the Entrance. Sand transfer recommended in May 1996 with the refurbished transfer plant and
discharge line. As of August 1998, approximately 370,000 cubic yards of sand had been transferred.
Of this amount, approximately 164,000 cubic yards is documented to remain within the 4,376 feet
north beach monitoring segment. The volume change within this segment over the April to August
1998 monitoring period is +43,600 yd3. This is interpreted as accumulation resulting from the
northerly directed sediment transport which occurs dominantly during the summer season.
SUMMARY AND CONCLUSIONS
This report has presented an analysis of the changes occurring in the Project area associated with the
Midtown Beach Nourishment Project. Nourishment of this project commenced 2.8 years and was
completed 2.6 years prior to the most recent survey in August 1998.
Based on the six post-nourishment surveys representing approximately 2.8 years since nourishment,
the Midtown Beach project has performed quite well. Of the 880,000 cubic yards placed, there are
some 593,300 cubic yards remaining in the placement area. As shown from Figure 7, the volume has
decreased only slightly during the last intersurvey interval. The additional plan area has increased
slightly during the last intersurvey interval, from 10.6 acres to 11.2 acres. This area is relative to the
pre-nourishment condition when there was almost no beach. As of the August 1998 survey,
approximately 67% of the volume placed remained in the placement area and 55% of the dry beach
plan area was present.
The monitored north beach area accumulated approximately 43,600 yd3 during the most recent
intersurvey period.
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-97/001.
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-97/013.
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-97/015.
Dean, R. G. (1998) "Midtown Beach Nourishment Project in Palm Beach, Florida: October 1995 to
April 1998", University of Florida, Department of Coastal and Oceanographic Engineering
Department, Report No. UFL/COEL-98/012.
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