HomeMy Public PortalAboutFl Inland Nav. Dist. (FIND) Development & Annex AgmtJones, Foster, Johnston 6 Stubbs, P.A.
505 Santh Flagler rive
West Palm Beach ,L 33401
WILL CALL #85 ✓/ XT -20-1994 11:54am r?4-35 31 ,
091294-10 OPO 8472 Pg 914
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DEVELOPMENT AND ANNEXATION AGREEMENT -�y� /
This Development and Annexation Agreement is entered into this -c / e!I
day of S�PrE.yt3c�, 1994, between the FLORIDA INLAND NAVIGATION
DISTRICT, a political subdivision of the State of Florida ("FIND")
and the TOWN OF GULF STREAM, a Florida municipal corporation
("Town").
WITNESSETH:
WHEREAS, FIND is the owner of a parcel of real property located
in unincorporated Palm Beach County, Florida, which parcel is more
particularly described on Exhibit "A" attached hereto and made a
part hereof by reference ("Annexation Parcel"); and
WHEREAS, the Annexation Parcel is contiguous with the municipal
boundary of the Town; and
WHEREAS, the Town is seeking to annex the Annexation Parcel into
the Town; and
WHEREAS, annexation of the Annexation Parcel is not inconsistent
with the Town's Comprehensive Plan; and
WHEREAS, Town and FIND agree that, among other things, lack of
certainty in the approval of development by Town can result in a
waste of economic and planning resources, discourage sound capital
planning and financing, escalate the cost of housing and
ORB E;4> Ps X05
development, and discourage commitment to comprehensive planning,
and therefore Town and FIND enter into this Agreement; which is
prepared consistent with and in compliance with the provisions and
intent of the "Florida Local Government Development Agreement
Act," Section 163.3220 et seq., Florida Statutes ("Development
Agreement Act");
WHEREAS, FIND desires to obtain the privileges and benefits
which accrue to and flow from annexation into the Town, among
which, given its present and potential future use, include
appropriate future designation of the Annexation Parcel in the
Comprehensive Plan and Zoning Maps, and the benefit of having such
Town services as, among others, parks and recreation, emergency
services, fire and police protection; and
WHEREAS, the Town desires that the purposes stated above for the
Annexation Parcel be accomplished and the Town desires to obtain
the additional benefits which may accrue if the Annexation Parcel
is annexed, including among others, expanded markets for various
of its municipal services; and expansion of the Town's boundaries;
and
WHEREAS, the desires of FIND and Town can best be achieved to
their mutual satisfaction by the execution of this Agreement which
expressly states their mutual rights, privileges and obligations
if the Annexation Parcel is annexed; and
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WHEREAS, FIND is also the owner of a parcel of real property
located within the boundaries of the Town which parcel is more
particularly described on Exhibit "B" attached hereto and made a
part hereof by reference ("Existing Parcel") (the Annexation
Parcel and the Existing Parcel shall be referred to, collectively,
as the "FIND Property"); and
WHEREAS, FIND has the statutory duty to, among other things,
develop long-range plans and acquire and manage sites for
maintenance of the intracoastal waterway and for dredged material
management; and
WHEREAS, the Town directly and indirectly benefits from the
activities of FIND; and
WHEREAS, the FIND Property is an integral part of FIND's plans
and, as such, it is in the best interest of FIND and the Town to
make appropriate provisions to assure the availability of the FIND
Property for dredged material management (as more fully set forth
in those certain reports prepared by Taylor Engineering, Inc.
dated March, 1992 and April, 1992, respectively, att
as Exhibit "C" and incorporated herein by reference); a
WHEREAS, the Town has determined that this A(
consistent with and promotes the achievement of the goals and
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objectives of the Comprehensive Plan of the Town of Gulf Stream,
Florida.
NOW, THEREFORE, in consideration of and in reliance upon the
mutual promises, covenants and recitals herein, the Town and FIND
agree as follows:
Section 1. Incorporation of Recitals.
The foregoing recitals are true and correct and are
incorporated into this Agreement by reference.
Section 2. Real Property Subject to this Agreement.
The real property subject to this Agreement is more
particularly described in Exhibit "A" and Exhibit "B" attached
hereto and made a part of this Agreement by reference.
Section 3. Annexation of Property.
FIND agrees to the annexation of the Annexation Parcel into
the Town and Town agrees to adopt an annexation ordinance in
accordance with the terms and conditions contained in this
Agreement.
Section 4. Duration of Agreement.
The duration of this Agreement shall be the maximum duration
allowed by law. This Agreement may be renewed by mutual consent
of FIND and Town to the extent that any such renewal is not
contrary to law.
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Section 5. Application for Annexation; Application of Current and
Future Town Laws; Procedures; and Policies; General
Duty to Approve Development Permits; vested Rights.
5.1 Application for Annexation.
Town has applied for annexation of the Annexation Parcel
and will continue to pursue the annexation at Town's expense.
5.2 Application of Current Town Laws, Procedures and Policies.
As provided in Section 163.3233, Florida Statutes, and
except as otherwise provided in this Agreement, Town shall,
during the duration of this Agreement, apply to the FIND
Property only those local laws, ordinances, administrative
orders and procedures, and policies governing development of
land which were adopted, in force and a matter of record on
the effective date hereof.
5.3 Application of Future Town Laws, Procedures, and Policies.
To the extent that this Agreement does not specifically
provide to the contrary, Town may apply to the FIND Property
those local laws, ordinances, administrative orders and
procedures and written policies governing development of land
adopted after the effective date hereof, however it may do so
only to the extent and in the manner provided in Section
163.3233(2), Florida Statutes.
5.4 Submission of Applications and Expeditious Review.
It is the intention of the parties that Town or its
authorized representatives shall prepare and, subject to
approval by FIND, which approval shall not be unreasonably
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withheld, submit to the Town such applications and other
documentation and shall comply with such other procedures as
may be normally, reasonably and customarily required by the
Town for Comprehensive Plan amendments and rezonings. The
Town agrees to process all such submissions, applications and
development requests expeditiously.
5.5 Permitted Development Uses.
For the duration of this Agreement,
the development uses
permitted on the FIND Property shall be
limited to dredged
material management and uses accessory or
ancillary thereto,
such as passive parks or other uses not
in conflict with the
FIND Property's use for dredged material
management and which
are consistent with the Zoning Code of the Town, as well as
any other uses authorized by an amendment
to this Agreement
pursuant to Section 10 hereof. No other uses
shall be allowed
except with the Town's consent. Dredged
material management
activities on the Find Property shall
be in substantial
conformity with Exhibit "C".
5.6 Public Facilities Serving FIND Property.
The parties recognize that dredged material management
use does not create a demand for new public facilities.
5.7 Local Development Permits.
FIND or its agents, contractors, assignees or designees
shall apply for and obtain all local development permits, if
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any, required for the development of the FIND Property, except
as provided in Sections 6.2 and 7.1, below, and subject to the
provisions of Section 5.2 , 5.3 and 7.3. The Town agrees that
any local development permits issued by the Town shall not be
unreasonably withheld or delayed.
Section 6. Comprehensive Plan Status.
6.1. Consistency with Comprehensive Plan.
Town agrees that its entering into and approval of this
Agreement are consistent with and are in no way precluded by
the Comprehensive Plan and Land Development Regulations of the
Town of Gulf Stream.
6.2 Application for Comprehensive Plan Amendment.
Town Staff shall prepare, file and process to completion
an application with the Town, at Town's expense, for amendment
of the Town Comprehensive Plan conferring upon the FIND
Property a land use designation which is consistent with its
use as a dredged material management site, within eighteen
(18) months of the enactment of the ordinance annexing the
Annexation Parcel into the Town.
Section 7. Zoning Status.
7.1 Application for Rezoning.
At the time Town Staff applies for an amendment to the
Town's Comprehensive Plan as provided in Section 6.2, above,
Town Staff shall prepare and file a concurrent application to
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establish the zoning of the FIND Property, at Town's expense.
Town Staff shall request and Town shall approve a rezoning to
a zoning district in which dredged material management is a
permitted use by right and which is consistent with the Town's
Comprehensive Plan and/or as that Comprehensive Plan may have
been amended pursuant to Section 6.2., above.
7.2 Amendment of Land Development Regulations.
In the event that the Town's Land Development Regulations
do not provide a zoning district as contemplated by Section
7.1 above, then the Town shall amend the Land Development
Regulations to authorize such zoning district or to amend an
existing zoning district, at the earliest opportunity,
whereupon the FIND Property shall be rezoned as contemplated
by Section 7.1 above, such rezoning to be effective within
thirty (30) days of a final order by the Department of
Community Affairs or the Administration Commission finding the
Comprehensive Plan Amendment as provided in Section 6.2. above
to be "in compliance."
7.3 No Restrictions upon Dredged Material Management Use.
Town shall not enact, adopt or enforce any ordinance
applicable to the FIND Property which prohibits or would have
the effect of prohibiting the use of the FIND Property as
dredged material management sites. Town shall not designate
the FIND Property in the Town Comprehensive Plan, Town Land
Development Regulations, or otherwise, or take any other
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action that would result in the designation or use of the FIND
Property as a conservation area, preserve area, habitat for
rare, threatened or endangered plant or animal species, or
species of special concern, or any other designation which
would substantially limit the use of the FIND Property for
dredged material management. Specifically, and without
limiting the generality of the foregoing, the provisions of
Chapter 58, Article IV of the Town Code of Ordinances shall
not apply to the FIND Property.
7.4 Effect of Failure to Amend Comprehensive Plan and/or
Rezone FIND Property.
In the event that the Comprehensive Plan is not amended in
accordance with Section 6.2, above, and/or the FIND Property
is not rezoned in accordance with Section 7.1, above, within
the time limitations provided therein or as extended by mutual
agreement of the parties, FIND may notify Town of its election
to terminate this Agreement. Upon receipt of the FIND's
notice of intent to terminate, Town shall take all necessary
action to rescind the annexation ordinance, whereupon this
Agreement shall terminate. The annexation ordinance
contemplated by Section 3, above, shall specifically provide
for rescission under the circumstances described above.
Section 8. Effect of Agreement on Town Ordinances• Effect of
Subsequent Changes in Law.
8.1 Effect of Agreement on Town Ordinances.
Except as otherwise specifically provided herein, nothing
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contained in this Agreement shall be deemed to limit in any
manner whatsoever the right of the Town, now or in the future,
to amend its Comprehensive Plan, Zoning Code, Building Code or
other land development codes or ordinances to protect the
public health, welfare, safety and conveniences in a manner
that it could otherwise do if this Agreement were not in
existence. Except as otherwise specifically provided herein,
none of the provisions herein shall be deemed to amend, modify
or otherwise change any provision of the regulations or
ordinances of the Town or any other governmental agency.
Except as provided in Section 5, above, any matter not
specifically addressed or modified by this Agreement shall
comply with the laws, ordinances, and regulations of the
Town. The failure of the Agreement to address a particular
permit, condition, term or restriction shall not relieve FIND
of the necessity of complying with the law governing said
permitting requirements, conditions, term or restriction.
8.2 Changes in Town Ordinances and Policies.
Town agrees that the Property shall be governed by
subsequent changes in Town ordinances and policies only to the
extent provided in Section 163.3233, Florida Statutes and in
Section 5, above.
8.3 Changes in Countywide. State or Federal Law.
If changes in countywide, state or federal law enacted
after the execution of this Agreement prevent compliance
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herewith by either party, Town and FIND agree that the
Agreement shall be modified or revoked as necessary to comply
with the applicable state or federal law as provided in
Section 163.3241, Florida Statutes.
Section 9. Agreement to Run With Land.
This Agreement, and the benefits and burdens thereof, shall
run with the land (i.e., the FIND Property) and shall inure to the
benefit of, and be binding upon, FIND and its successors and
assigns.
Section 10. Amendment or Termination of Agreement.
This Agreement may be amended or terminated by mutual consent
of the parties or as provided in Section 163.3237, Florida
Statutes.
Section 11, Recording.
This Agreement is to be recorded by Town in the Public Records
of Palm Beach County, Florida. Town shall forward a copy of the
recorded Agreement to the Florida Department of Community Affairs.
Section 12, Notice.
Notices required to be given by this Agreement shall be in
writing sent by certified United States Mail, return receipt
requested, addressed to the person to whom it is intended at the
place specified for giving notice, or at such other place as shall
be designated by written notice specifically referring to this
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Agreement. The parties designate the following as the respective
places for giving notice:
For the Town: Town of Gulf Stream, Florida
Town Hall
100 Sea Road
Gulf Stream, Florida 33483
ATTN: Town Manager
For FIND: Florida Inland Navigation District
1314 Marcinski Road
Jupiter, Florida 33477
ATTN: Executive Director
Section 13. Entire Agreement.
This Agreement constitutes the entire contract between the
parties hereto and supercedes all prior understandings, if any.
There are no other oral or written promises, conditions,
representations, understandings or terms of any kind as conditions
or inducements to the execution hereof and none have been relied
on by either party. Any subsequent conditions, representations,
warranties or agreements shall not be valid and binding upon the
parties unless they are in writing signed by both parties and
executed in the same manner as this Agreement.
Section 14. Severability.
In the event any term or provision of this Agreement shall be
held invalid, such invalid term or provision shall not affect the
validity of any other term or provision hereof and all such other
terms and provisions hereof shall be enforceable to the fullest
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extent permitted by law as if such invalid term or provision had
never been a part of this Agreement.
Section 15. Jurisdiction and Venue.
This Agreement shall be construed, and the rights and
obligations of Town and FIND hereunder shall be determined, in
accordance with the laws of the State of Florida. Venue of any
litigation pertaining to the subject matter hereof shall be
exclusively in Palm Beach County, Florida.
Section 16. Attorney's Fees.
In the event of the bringing of any action or suit by a party
hereto against another party hereunder by reason of any breach of
any of the covenants, agreements or provisions on the part of the
other party arising out of this Agreement, the prevailing party
will be entitled to recovery from the non -prevailing party of all
costs and expenses of the action or suit, including without
limitation, reasonable attorney's fees, including appellate and
post -judgment proceedings, witness fees and any other reasonable
professional fees resulting therefrom.
Section 17. Enforcement.
This Agreement shall be enforced as provided in Section
163.3243, Florida Statutes.
Section 18. Effective Date.
This Agreement shall become effective upon its recordation
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ORB $4-7-? Pn 9-1
with the Clerk of the Palm Beach County Circuit Court by the Town
promptly after its approval by the local government and upon
thirty (30) days having passed from it having been received from
the Town by the Florida Department of Community Affairs.
IN WITNEgSJ,Sli7 WHEREOF th parties have executed this Agreement as
of the O.( day of , 1994.
WITNESSES:
.�
Typed or Printed Name
(z)
Typed or Printed Name
STATE OF FLORIDA )
COUNTY OF PALM BEACH )
FLOR
a po
Stat
By:
IGF,VON DISTyt7T,
isUn of nth /
to
Typed 0&1
d Name
Title
(CORPORATE SEAL)
� �o�r to and subscribed be ore me Ahi «7- day
of .x��-I , 1994, byfn/i �I�O[
as of FLORIDA INLAND NAVIGATION DISTRICT, a
political subdivision of the State of Florida, on behalf of the
District, and who is:
personally known to me, OR
has produced
V"'14 CINDYLSOLM
(NOTARY STA M * neycO"� Cr361023
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as identification.
Notary N e: /NDt/ OLES
Notary PYiblic t
Serial (Co ssion) Number
(if any) C 3S/DZ 3
38408
S!4 s9 jSj;6fx 99C,
(SEAL)
STATE OF FLORIDA
COUNTY OF PALM BEACH
ORB 8472 FT Q18
TOWN OF GULF STREAM, FLORIDA,
a Florida m co po tion
ByY�
7�1-lliam F. Koch.' Jr.
Mayor
ATTEST:
own Clerk
BEFORE ME, the undersigned authority, personally appeared
WILLIAM F. KOCH, JR. and RITA L. TAYLOR, the Mayor and Town Clerk
respectively of the TOWN OF GULF STREAM, who are personally known
to me, and they acknowledged before me that they executed the
foregoing instrument as such officers of the Town of Gulf Stream,
duly authorized for the purposes therein expressed.
WITNESS my hand and seal in the County and State last
aforesaid this /Y day of ac% � , 1994.
nature of Notary Pu
nted Name of Notary
LZ' a7f,?Il
imi.ssion aumner
S u
NOTARY PUBLiC, STATE OF FLORIDA.:
161Y COMMISSION EXPIRES: Jan. 27, 1995.
•y •,,
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BONDED TBRU NOTARY PUBLIC UNDERWRITERS.
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3840B
ORB 8472 Ps 919
MSA 641A
(Two Tracts)
Tract No. 1 - Lying in the Southwest Quarter of the Southeast
Quarter of the Southeast Quarter, Section 4, Township 46 South Range
43 East.
Commencing at the Southeast corner of Section 4, Township 46 South,
Range 43 East, as a point of reference; thence along the South boundary
line of said Section 4, South 89048'05" West; 1344.47 feet to an inter-
section with the Westerly right-of-way line of the hereinbefore mentioned
Intracoastal Waterway; thence along said Westerly right-of-way line North
11°36'46" East, 73.05 feet to an intersection with the west line of the
Southeast Quarter of the Southeast Quarter of said Section 4, to the
Point of Beginning, identical with the Point of Beginning of a tract of
land known as Maintenance Spoil Area 641 and recorded in Deed Book 506,
at Page 92, of the said public records of Palm Beach County, Florida;
thence along the West line of said Maintenance Spoil Area 641 identical
with the West line of said southeast quarter of the Southeast Quarter
of Section 4, Township 46 South, Range 43 East, North 1038'32West,
616.56 feet to the North line of the Southwest Quarter of the Southeast
Quarter of the Southeast Quarter of said Section 4; thence along said
North line North 89046' 14" East, 144.45 feet to the Westerly right-of-
way line of the Intracoastal Waterway; thence along said Westerly right -
of -Way line South 11°36'46" West, 629.82 feet to the Point of Beginning,
containing 1.02 acres, more or less.
Tract No. 2 - Lying in the Southeast Quarter of the Southwest Quarter
of the Southeast Quarter, Section 4, Township 46 South Range 43 East
The Point of Reference and the Point of Beginning being identical
with those of the hereinabove described Tract No. 1.
From said Point of Beginning run along the hereinbefore mentioned
Westerly right-of-way line of the Intracoastal Waterway from Jacksonville
to Miami, Florida, South 11036'46" West, 73.05 feet to the South boundary
line of Section 4, Township 46 South, Range 43 East, thence along said
South boundary line South 89048'05" West, 647.10 feet to the Southwest
corner of the Southeast Quarter of the Southwest Quarter of the Southeast
Quarter of said Section 4, marked by a concrete monument; thence along
the Westerly line of said Southeast Quarter of the Southwest Quarter of
the Southeast Quarter, North 1029136" West, 687.72 feet to the North
line of said Southeast Quarter of the Southwest Quarter of the Southeast
Quarter, said North line being identical with the Westerly prolongation
of the hereinbefore mentioned North line of the Southwest Quarter of the
Southeast Quarter of the Southeast Quarter of Section 4; thence along
said North line North 89046'14" East, 662.06 feet to the Northwest corner
of the hereinbefore described Tract No. 1; thence along the West line
of said Tract No. 1, South 01038'32" East, 616.56 feet to the Point of
Beginning.(containing 10.46 acres, more or less.
ORB 8472 Pe ?20
EXHIBIT "B"
MSA 640A
All that certain tract or parcel of land situated in the Southeast
Quarter of the Northeast Quarter of Section 4, Township 46 South, Range
43 East, Palm Beach County, Florida, more particularly described as follows;
Commence at the Southeast corner of said Section 4 as a point of
reference; thence North 01° 56' 23" West, 2755.62 feet along the Easterly
boundary of said Section 4 to the Quarter Section Corner; thence South
890
40 42 West, 685.06 feet along the Southerly boundary of the Southeast
Quarter of the Northeast Quarter of Section 4, Township 46 South, Range
43 East, to a point on the Westerly right of way line of the Intra-
coastal Waterway from Jacksonville to Miami, Florida, as said right of way
line is shown on a map recorded in the Public Records of said Palm Beach
County in Plat Book 17, at Page 14-A; thence continuing South 89040'42"
West, 367.95 feet along the aforesaid South boundary of the Northeast
Quarrer Section line as a point of beginning.
Thence from the point of beginning above described, continuing
along aforesaid Quarter Section line North 89040'42" West, 260.31 feet
to a pipe marking the Southwest Corner of the Southeast Quarter of the
Northeast Quarter of aforesaid Section 4; thence North 01039'28" West,
452.82 feet along the Westerly boundary of the Southeast Quarter of the
Northeast Quarter of said Section 4; thence North 89140'42" East, 735.03 feet
to a point on the Westerly right of way line of the above mentioned Intra-
coastal Waterway; thence continuing along said Westerly right of way line
South 11°36'46" West, a distance of 100.00 feet; thence South 89°40'42"
West, 367.95 feet; thence South 11036'46" West, 362.70 feet to the point
of beginning. I
Containing 4.09 acres, more or less.
MSA 640
That portion of the South 355 feet of the SE4 of the NEq of
Section 4, Township 46 South, Range 43 East, Palm Beach County, Florida,
embraced in a zone 360 feet wide when measured at right angles to'and
lying West of and immediately adjoining the West right of way line of
the Intracoastal Waterway from Jacksonville to Miami, Florida, as that
right of way line is shown on the plat recorded in Plat Book 17, at Page
14-A, of the public records of said Palm Beach County, Florida.
Containing 3.00 acres, more or less.
R
UM 84-12 Pe V21
EXHIBIT "C"
Engineering Narrative
MSA 641A Disposal Area
This narrative summarizes the documents comprising the permit application package for the
development of the MSA 641A dredged material containment area. Site MSA 641A will be a permanent
facility to service the maintenance requirements of Reach IV of the Intracoastal Waterway (ICWW) in Palm
Beach County, Florida from the S.R. 812 bridge in Lantana, to the southern county line (ICWW mile
291.72 to mile 310.22).
The submission of this application package represents an intermediate step towards completion of the
second phase of a two phased program element addressing the maintenance requirements of the Intracoastal
Waterway in Palm Beach County, Florida. This element is part of a fifteen year program sponsored by the
Florida Inland Navigation District to develop a long-term dredged material management plan for the
Intracoastal Waterway along the entire east coast of Florida. Phase I of the Palm Beach County program
element, which is documented in two reports included as Attachments I, and 2 to this permit application,
developed basic plan concepts for the continuing management of maintenance material dredged from the
Intracoastal Waterway in Palm Beach County, defined short and long term program needs based on a
comprehensive examination of historical dredging records for the project area, and identified suitable
centralized sites which satisfy these needs based on preliminary environmental, engineering, and operational
criteria. Phase II consists of the gathering of detailed, site specific information required for the preparation
and submission of permit applications for the eight primary containment sites identified in Phase I. In
addition, Phase II also addresses the preliminary design of the site containment facilities; the acquisition of
these sites (where appropriate), through negotiated purchase or condemnation, by the Florida Inland
Navigation District; and the construction and continuing operation and maintenanee of these sites as
permanent dredged material management facilities.
No attempt is made in this narrative to recount, in detail, the information contained in the documents
which accompany the permit application. Rather, this narrative is designed to assist the reviewer in
organizing this information, while emphasizing the engineering considerations and design specifications
presented in the attached permit drawings (Attachment 3). In addition to the permit drawings and the Phase
I reports already mentioned, the permit application package for Site MSA 641A includes: Attachment 4, a
topographic survey, documenting pre -construction topography and drainage patterns, and providing
information necessary for site design, volumetric calculations, and grade analysis; Attachment 5, the sub-
surface and soils report, identifying site foundation conditions and in-situ construction material suitability,
as well as locating the water table on-site; Attachment 6, the environmental report, documenting existing
ORB 8-47 Ps 92
DOROTHY H. WIL KENT CLERK PB COUNTY! Fl.
THE FULL TEXT OF EXHIBIT "C" IS ON FILE WITH
THE CLERK OF THE TOWN OF GULF STREAM AND MAY
BE REVIEWED AT THE GULF STREAM TOWN HALL, 100
SEA ROAD, GULF STREAM, FLORIDA.
EXHIBIT "C" APPLIES TO MSA 641A DISPOSAL AREA
AND MSA 640/640A DISPOSAL AREA
Engineering Narrative
MSA 640/640A Disposal Area
This narrative summarizes the documents comprising the dredge and fill permit application package
for the development of the MSA 6401640A dredged material containment area. Site MSA 640/640A will
be a permanent facility to service the maintenance requirements of Reach IV of the Intracoastal Waterway
(ICWW) in Palm Beach County, Florida from the S.R. 812 bridge in Lantana, to the southern county line
(ICWW mile 291.72 to mile 310.22).
The submission of this application package represents an intermediate step towards completion of the
second phase of a two phased program element addressing the maintenance requirements of the Intracoastal
Waterway in Palm Beach County, Florida. This element is part of a fifteen year program sponsored by the
Florida Inland Navigation District to develop a long-term dredged material management plan for the
Intracoastal Waterway along the entire east coast of Florida. Phase I of the Palm Beach County program
element, which is documented in two reports included as Attachments 1, and 2 to this permit application,
developed basic plan concepts for the continuing management of maintenance material dredged from the
Intracoastal Waterway in Palm Beach County, defined short and long term program needs based on a
comprehensive examination of historical dredging records for the project area, and identified suitable
centralized sites which satisfy these needs based on preliminary environmental, engineering, and operational
criteria. Phase II consists of the gathering of detailed, site specific information required for the preparation
and submission of permit applications for the eight primary containment sites identified in Phase I. In
addition, Phase II also addresses the preliminary design of the site containment facilities; the acquisition of
these sites (where appropriate), through negotiated purchase or condemnation, by the Florida Inland
Navigation District; and the construction and continuing operation and maintenance of these sites as
permanent dredged material management facilities.
No attempt is made in this narrative to recount, in detail, the information contained in the documents
which accompany the permit application. Rather, this narrative is designed to assist the reviewer in
organizing this information, while emphasizing the engineering considerations and design specifications
presented in the attached permit drawings (Attachment 3). In addition to the permit drawings and the Phase
I reports already mentioned, the permit application package for Site MSA 640/640A includes: Attachment
4, a topographic survey, documenting pre -construction topography and drainage patterns, and providing
information necessary for site design, volumetric calculations, and grade analysis; Attachment 5, the sub-
surface and soils report, identifying site foundation conditions and in-situ construction material suitability,
as well as locating the water table on-site; Attachment 6, the environmental report, documenting existing
environmental conditions, including vegetation communities and wildlife habitats, and serving to guide the
configuration of the containment area within the site so as to avoid, to the greatest extent possible, the most
sensitive environmental areas; and Attachment 7, a site specific management plan, insuring that the
containment area will continue to be operated in an efficient manner without undue conflicts with adjacent
off-site land use, and allowing the site to be maintained as a permanent facility.
Site MSA 640/640A comprises two contiguous parcels, MSA 640 and MSA 640A, owned by the
Florida Inland Navigation District with a total area of 7.09 acres. The site is located near the city of
Boynton Beach, on the western shore of the ICWW (Attachment 3, Sheet 1 of 3). It is bounded on the north
and south by residential developments, and on the west by a parcel of undeveloped land. Soils on the site
consist predominantly of an Arents-Urban complex, which is a poorly drained sandy fill overlying organic
soil. No historical or archaeological sites are recorded for this property, based on a review of the Florida
Master Site File.
Vegetation in the northern portion of the site consists mainly of Brazilian pepper (422) and Australian
pine (437) communities. A variety of residential landscaping species have been planted in the disturbed
southern portion of the site including St. Augustine grass, cabbage palms and Washington palms. Other
species occurring in this area are frog fruit, crowgrass, and hairy spurge. The northeast corner of the site,
which extends into the ICWW, is submerged, however no other wetlands are present on site. Detailed
environmental information for Site MSA 6401640A is provided in the attached environmental report
(Attachment 6).
The preliminary site design layout includes a buffer area surrounding the containment area, separating
it from adjacent properties (Attachment 3, Sheet 2 of 3). The buffer on the north, south, and west sides of
the site will be approximately 50 ft wide, while the eastern buffer will vary in width from 25 to 60 ft. A
portion of this buffer will consist of undisturbed vegetation occurring along the site perimeter.
The proposed containment area is defined by earthen dikes to be constructed of material excavated
from the site interior. The existing mean elevation of the projected containment area was determined from
topographic survey (Attachment 4) to be +6.07 feet NGVD. Specific soil and foundation information
(soils/sub-surface report, Attachment 7) confirm the utility of the preliminary facility design as being well
within the range of standard COE practice for similar sites and materials. Design dike specifications include
2
an initial dike crest height of 6.0 ft above grade (+12.07 ft NGVD), a side slope of 1V:3H, and a crest
width of 12.0 ft, yielding a dike width at grade of 48 ft. As measured at the crest centerline, the dike
perimeter is 1,812 ft, requiring 10,822 c.y. of material to construct. The containment basin will provide
a capacity of 18,382 c.y., which is approximately 12 per cent of the projected 50 yr disposal requirement
(158,000 c.y.) for Reach IV. The remainder of the reach requirement will be met by the utilization of three
additional dredged material management sites located elsewhere in the reach.
An additional feature of the containment structure is a ramp to allow ingress and egress of heavy
equipment to and from the interior of the diked area. Ramp details are shown in the permit application
drawings (Attachment 3, Sheets 2 and 3 of 3). The outside of the ramp and the supporting toe maintain the
same 1V:3H slope as the main dike. The ascending/descending grade is 5 per cent. These ramps will
facilitate the regrading of material deposited in the containment basin to promote complete dewatering and
ensure proper stormwater collection and drainage. In addition, the ramps will provide an efficient means
of removing the material for use as detailed in the site-specific management plan (Attachment 9), as
prevailing restrictions and market conditions dictate.
The total volume of material initially required for the ramp construction is 603 c.y. which, when
added to the initial dike requirement of 10,822 c.y., yields a total construction material requirement of
11,425 c.y. This is to be provided by the uniform excavation of the containment area interior to an average
depth of +2.55 ft NGVD (3.20 ft below grade), maintaining the 1 V:3H dike slope and a 20 foot excavation
setback from the interior toe of the dike. Allowing for 2 ft of freeboard, and an additional 2 ft of ponding
depth at the completion of final dredging operations (Le, filling the containment area to 4 ft below the dike
crest, or 5.20 ft above the excavated interior grade elevation) yields an initial site disposal capacity of 18,382
cy. Also to be noted is the existence of the on-site water table located at a mean elevation of +1.81 ft
NGVD, or 0.74 ft below the mean excavation grade, at the time of the sub -surface survey. Therefore, a
sump and/or pumping of groundwater seepage may be required during construction, due to the close
proximity of the water table to the finished interior grade.
Inlet pipeline access to the site from the Waterway will be located approximately 30 ft south of the
northern site boundary (Attachment 3, Sheet 2 of 3). The inlet pipeline will be routed along the northern
side of the containment dike, entering the basin near its northwest corner by passing over the dike crest
(Attachment 3, Sheet 2 of 3).
3
Decanting of the ponded water will be accomplished by a parallel arrangement of three (3) corrugated
metal half -pipes, located in the southeast corner of the containment area, diagonally opposite the slurry inlet
(Attachment 3 Sheet 2 of 3). Each half -pipe will provide for the release of effluent over a sharp -crested weir
section of minimum length of 8 ft, for a total minimum crest length of 24 ft. The weir crest height will be
adjustable by means of removable flash boards from the excavated basin interior grade to 6.9 ft above the
interior grade. The minimum weir crest elevation facilitates the control of stormwater runoff prior to
disposal operations, while the maximum elevation facilitates control of the final elevation of the deposition
layer surface. The three weirs are to be connected by a manifold, with a single outlet pipe passing under
the dike and extending approximately 60 ft to the ICWW.
The specification of a minimum weir crest length of 24 ft is based on U.S. Army Corps of Engineers
guidelines related to the dredge equipment. For this and all project calculations, it has been assumed that
an 18 inch O.D. dredge, (discharge velocity of 16 ft/sec, a volumetric discharge of 3,560 c.y./hr, and a
20/80 solids/liquid slurry mix) would be used for future channel maintenance. Analysis of weir performance
based on nomograms developed at the COE Waterways Experiment Station (WES) under the Dredged
Material Research Program (DMRP) (Walski and Schroeder, 1978) indicates that these design parameters
may be expected to produce an effluent suspended solids concentration of 0.45 g/1, assuming a minimum
average ponding depth of 2 ft. Translation of suspended solids concentration to a measure of turbidity on
which Florida water quality standards are based is highly dependent on the suspended material
characteristics. However, WES guidelines (Palermo, 1978) indicate that the estimated effluent suspended
solids concentration of 0.45 g/I correlates to an acceptable level of turbidity. Should effluent quality
deteriorate below the ambient conditions of the receiving waters, steps shall be taken to decrease effluent
turbidity. These may include intermittent dredge operation, increased ponding depth, or the use of turbidity
curtains surrounding the site outlet weirs.
Road access to the site will be provided via a separate road easement, connecting the site to Federal
Highway (U.S. 1), which lies approximately 600 ft west of the western site boundary (Attachment 3, Sheet
2 of 3). The access road connection will enter the site near the southwest property corner.
A system of perimeter ditches will be constructed at a 20 ft setback from the outside toe of the
containment dike to control stormwater runoff from the exterior face of the containment dike, perimeter
road, and portions of the buffer area. These ditches will also provide a means for intercepting any
al
horizontal migration of saltwater from the interior of the containment area. Preliminary analysis indicates
that at a minimum depth of 2.8 ft, the ditches will provide adequate conveyance for the 25 yr storm runoff.
Finally, as part of this application an analysis of containment area efficiency was performed. No data
are available to characterize the channel sediments in Reach IV of the ICWW in Palm Beach County.
Therefore, the analysis was based on a conservative estimate that the sediment to be encountered within this
reach includes up to 25 per cent silt, that is, up to 25 per cent of the material would pass a #200 sieve. This
estimate is supported by the experience of the Jacksonville District Corps of Engineers. From the estimated
silt content of the sediment to be dredged, a characteristic zone settling velocity was determined from an
empirical relationship between silt content and settling behavior. This relationship was developed from
Corps of Engineers sediment data characterizing the silt content of a variety of ICWW channel sediments
and the corresponding settling behavior of slurry concentrations similar to those typically encountered in
dredging operations (Attachment 7). The resulting zone settling velocity for the sediment to be placed in
Site MSA 640/640A was determined to be 0.5 cm/min. This settling velocity was then used to determine
the retention time needed to provide adequate sedimentation within the containment basin.
Analysis of the hydraulic characteristics of the proposed containment basin indicates that a 2 ft
ponding depth provides a maximum retention time of 3.03 hours during the period in which flow over the
weir balances the liquid discharge of the dredge. In comparison, the time required for the suspended
sediment to settle out of the withdrawal layer of 2 ft is 2.03 hours, based on the zone settling velocity
derived above. Research by the U.S. Army Waterways Experiment Station (WES) under the Dredged
Material Research Program (DMRP) (Shields et al., 1987) indicates that to account for field conditions, the
required settling time should be multiplied by a safety factor of 2.25. This corrected settling time of 4.57
hrs exceeds the calculated maximum retention time of 3.03 hours produced by the minimum ponding depth
of 2 ft. Therefore, it is recommended that a minimum operational ponding depth of 4 ft be maintained
whenever possible. This would result in a basin retention time of 6.06 hours which is sufficient to maintain
the required effluent quality. Moreover, DMRP research indicates that under field conditions the depth of
withdrawal may be significantly less than that predicted by the WES Selective Withdrawal Model referenced
above. Therefore, providing the recommended operational ponding depth of 4 ft should eliminate the
possibility of resuspension, as well as doubling the retention time over that provided by a 2 ponding depth.
This should ensure that the turbidity of the effluent released from Site MSA 640/640A meets state water
quality standards. In order to achieve the maximum capacity of the containment basin, it will be necessary
to reduce the ponding depth to less than the recommended depth of 4 ft during the final stages of disposal
5
operations. At this time, additional measures may be required to maintain adequate water quality. These
include installing turbidity screens or floating baffles around the weirs, or requiring the dredge plant to shut
down until the surface water quality reaches acceptable limits.
C1]
REFERENCES
Palermo, M.R., R.L. Montgomery, and M.E. Poindexter, "Guidelines for Designing, Operating, and
Managing Dredged Material Containment Areas",Technical Report DS -78-10, Dec. 1978, U.S. Army
Engineer Waterways Experiment Station, CE, Vicksburg, MS.
Walski, T.M. and P.R. Schroeder, "Weir Design to Maintain Effluent Quality from Dredged Material
Containment Areas", Technical Report D-78-18, May 1978, U.S. Army Engineer Waterways
Experiment Station, CE, Vicksburg, MS.
7
80°0230 0
SPOSAL
TE MSA 640/640A
80°02301
l 1
0 2000,
_ . fc+
TAYLOR ENGINEERING INC C-9005
— Location of FIND MSA 640/640A
9086 CYPRESS GREEN DRIVE
JACKSONVILLE, FLORIDA 32256 Dredged Material Disposal Site 1 ora
Palm Beach County, Florida ° ` Mar., 1992
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ENVIRONMENTAL SITE DOCUMENTATION
FOR
PROPOSED DREDGED MATERIAL DISPOSAL AREAS
IN PALM BEACH COUNTY
VOLUME IV - MSA 640
Report Prepared Under Contract to:
TAYLOR ENGINEERING, INC., for the
FLORIDA INLAND NAVIGATION DISTRICT
Prepared by:
E. Lynn Mosura
WATER AND AIR RESEARCH, INC.
Gainesville, Florida
February 1991
File: 75301
TABLE OF CONTENTS
Table
1.0 INTRODUCTION
2.0 METHODOLOGY
3.0 VEGETATION COMMUNITIES
3.1 INTRODUCTION
3.2 BRAZILIAN PEPPER (422)
3.3 AUSTRALIAN PINE (437)
3.4 STREAMS AND WATERWAYS (510)
3.5 DISTURBED LAND (740)
3.6 ROADS AND HIGHWAYS (814)
3.7 ENDANGERED AND THREATENED PLANTS
4.0 WILDLIFE COMMUNITIES
4.1 WILDLIFE HABITAT
4.2 ENDANGERED AND THREATENED ANIMALS
5.0 WETLAND JURISDICTIONS
6.0 PIPELINE ACCESS
7.0 REFERENCES
FIND.17[WP]MSA640TC.1
02/08/91
Page
1-1
3-1
3-1
3-1
3-1
3-6
3-6
3-6
LIST OF FIGURES
Figure
FIND.17[WP]MSA640TC.2
02/08/91
Pape
1-1 Location of MSA 640 Proposed Dredged Material Disposal 1-2
Site, Palm Beach County, Florida
3-1 Land Use and Vegetation of MSA 640 Proposed Dredged Material 3-2
Disposal Site, Palm Beach County, Florida
LIST OF TABLES
Table
Pape
3-1 Approximate Acreage of the Florida Land Use, Cover and 3-3
Forms Classification System Found at the MSA 640 Proposed
Dredged Material Disposal Site, Palm Beach County, Florida
3-2 Vegetation Species by Community Type Found at the MSA 640 3-4
Proposed Dredged Material Disposal Site, Palm Beach
County, Florida
3-3 Status of State or Federally Listed Endangered and Threatened 3-7
Plants that May Occur at the MSA 640 Proposed Dredged
Material Disposal Site, Palm Beach County, Florida
4-1 Vertebrates and Invertebrates Observed at the MSA 640 4-2
Proposed Dredged Material Disposal Site, Palm Beach
County, Florida
4-2 Status of State or Federally Listed Endangered or Threatened 4-4
Wildlife that May Occur on the MSA 640 Proposed Dredged
Material Disposal Site, Proposed Pipeline Access, or Adjacent
Waters, Palm Beach County, Florida
1.0
FIND.17[WP]640-1-0.1
02/25/91
1.0 INTRODUCTION
A 50 -year dredged material management plan is being developed for the
Intracoastal Waterway (ICWW) along Palm Beach County, Florida. The plan
concept was developed during Phase I of the project (Bromwell and Carrier
1989). Potential sites were screened for dredged material disposal, and a
total of eight primary sites were selected after consideration of
environmental, engineering, and operational factors.
During the current Phase II effort, primary sites will undergo further
environmental scrutiny to assure the selection of sites with minimal
environmental constraints. This document reports the results of the
environmental survey carried out at one of these sites.
Site MSA 640 is located approximately 2 miles north of State Road 806
(Atlantic Ave.) and east of U.S. 1 along the western side of Lake Worth Creek
(ICWW) near Delray Beach (Figure 1-1). The 7.1 -acre site is adjacent to an
undeveloped parcel of land that fronts U.S. Highway 1. Property to the north
and south of the site is single family residential.
The soils on the site are predominantly Arents-Urban land complex. This soil
type is a somewhat poorly drained sandy fill that was placed over organic
soils in low, wet areas bordering the ICWW. The site elevation ranges from
below 5 feet along the ICWW to above 5 feet National Geodetic Vertical Datum
(NGVD) on the western side of the site.
A review of the Florida Master File indicates no historical or archaeological
sites known for this property.
The proposed pipeline route enters Site MSA 640 directly from the ICWW channel
located east of MSA 640.
1-1
80002'30" o
— r9i
IISPOSAL
ITE (MSA 640)
80°02 30'
REFERENCED
USGS DELRAY BEACH,FL.
QUADRANGLE 1962, PHOTO- I Y� I
REVISED 1969 AND1973.
0 2000'
FIGURE 1-1 Location MSA 640 "°""
TAYLOR ENGINEERING INC Proposed Dredged Material °i�L
9086 CYPRESS GREEN DRIVE Disposal Site, Palm Beach "
JACKSONVILLE, FLORIDA 32256
County, Florida
1-2
0
u
N
2.0 METHODOLOGY
FIND.17[WP]640-2-0.1
02/08/91
2.0 METHODOLOGY
A Water and Air Research, Inc. (WAR), biologist ground-truthed the site to
assess vegetation and wildlife conditions on September 5, 1990. During this
visit, incidental wildlife sightings were recorded and vegetative conditions
were noted.
Blueline aerial photography (1986 and 1989) at a scale of 1"=200' was used to
identify pertinent land use and vegetation features prior to the pedestrian
survey. During the field survey, all noted photographic signatures were
visited and plant species at these locations were identified or collected for
subsequent examination. Vegetation mapping was done on 1989 blueline aerials
(1"=200'). The frequency of occurrence of each plant species within each
identified community was determined using a qualitative ranking system.
Designations include abundant (A), locally abundant (LA), common (C), locally
common (LC), occasional (0), rare (R), and trace (X). The site was reviewed
for the presence and location of possible wetlands using the blueline aerial
photography mentioned above, as well as 1984 color infrared aerial photography
(1"=2,000'). The County Soil Survey and USGS topographic maps were also
consulted to locate possible wetlands on site.
The occurrence of wildlife species on site was documented during visits to
each vegetation community. Efforts were made to visit locations of high
wildlife habitat value. Areas that were likely to yield animal signs were
sought out (i.e., muddy roads/wetland edges). Indirect evidence (nests, scat,
and tracks) and direct observation (calls and visual sightings) were utilized
to confirm species present. All ecological surveys were conducted during
daylight hours, hence nocturnal wildlife observations were not made.
Prior to the field survey, lists of endangered and threatened species and
species of special concern possibly occurring on site were compiled based on
the range of the species and their environmental requirements. The locations
of sensitive species found on site were recorded and observations about
population size and habitat use were noted.
2-1
3.0 VEGETATION COMMUNITIES
FIND.17[WP]640-3-0.1
02/08/91
3.0 VEGETATION COMMUNITIES
3.1 'NTRODUCTION
Vegetation communities and land uses identified at Site MSA 640 and mapped in
Figure 3-1 include Brazilian pepper (422), Australian pine (437), streams and
waterways (510), disturbed land (740) and roads and highways (814). The
vegetation and land uses have been categorized to Level III of the Florida
Land Use, Cover and Forms Classification System (FDOT 1985). Acreages of the
various map units were determined by the use of a digitizer and are reported
in Table 3-1. Table 3-2 is a list of the vegetation species by community type
found at the site.
3.2 BRAZILIAN PEPPER (422)
The western portion of the site is vegetated by predominantly Brazilian
pepper. A few cabbage palm occur in this area, as well as live oak and
strangler fig. Ground cover is sparse in some areas because of the dense
Brazilian pepper cover, but where it occurs, it consists of Boston fern,
Virginia creeper and balsam apple.
3.3 AUSTRALIAN PINE (437)
Most of the site is covered with the exotic hardwood, Australian pine. Other
tree and shrub species found within this community include Brazilian pepper,
strangler fig, papaya, and cabbage palm. Along the ICWW a few mangroves occur
under the Australian pine canopy. They are scattered along the steeply sloped
shoreline and do not cover sufficient area to be mapped separately. Seaside
mahoe is also found occasionally near the ICWW.
Ground cover is dominated by a variety of rapidly invading exotic plant
species including Asian sword fern, philodendron, oyster plant, wandering jew,
and Madagascar periwinkle.
3.4 STREAMS AND WATERWAYS (510)
A small area of the ICWW occurs within Site MSA 640. This area is unvegetated
open water.
3-1
0 100 200 400
SCALE IN FEET
FIGURE 3-1. Land Use and Vegetation of MSA 640 Proposed Dredged Material
Disposal Site, Palm Beach County, Florida
Water and Air Research, Inc.
3,2
Consulting Environmental Engineers, SclentlsU, and Planner
T r r T t 1,}}{{{
n 4 4 4 4 4 4 4 4### 4
4 4 4#
4 4 4
P4Q4444444144444444#44510
4 4 4
q.422� 4 4#4#4 4#41437#+##
4#
04 # #####44###44#44444444#+
0
P 444+44#4444
814
U
O
422.
# 4 4 4
444
v
740
O
4
LEGEND
0 4 Q
422
BRAZILIAN PEPPER
#
437
AUSTRALIAN PINE
510
STREAMS AND WATERWAYS
740
DISTURBED LAND
814
ROADS AND HIGHWAYS
0 100 200 400
SCALE IN FEET
FIGURE 3-1. Land Use and Vegetation of MSA 640 Proposed Dredged Material
Disposal Site, Palm Beach County, Florida
Water and Air Research, Inc.
3,2
Consulting Environmental Engineers, SclentlsU, and Planner
FIND.17[WP]640-3-1.1
02/08/91
Table 3-1. Approximate Acreage of the Florida Land Use, Cover and Forms
Classification System Found at the MSA 640 Proposed Dredged
Material Disposal Site, Palm Beach County, Florida
Map I.D. No.
Name
Approximate
Acreage
422
Brazilian Pepper
1.0
437
Australian Pine
3.2
510
Streams and Waterways
0,2
740
Disturbed Land
2.7
814
Roads and Highways
T
TOTAL
7.1
* T — Trace
Source: WAR 1990.
3-3
FIND.17[WP]640-3-2.1
02/08/91
Table 3-2. Vegetation Species by Community Type Found at the MSA 640
Proposed Dredged Material Disposal Site, Palm Beach County,
Florida (Page 1 of 2)
Species Common Name Occurrence
BRAZILIAN PEPPER (422)
Trees and Shrubs
Ficus aurea Strangler fig R
Quercus virpiniana Live oak R
Sabal palmetto Cabbage palm 0
Schinus terebinthifolius Brazilian pepper C -A
Herbs and Ground Covers
Momordica sp. Balsam apple (E) R
Nephrolepis sp. Boston fern 0
Parthenocissus puinpuefolia Virginia creeper R-0
Philodendron sp. Philodendron X
AUSTRALIAN PINE (437)
Trees and shrubs
Araucaria excelsa
Norfolk island pine
X
Avicennia zerminans
Black mangrove
X -R
Brassaia actinophylla
Schefflera
X
Carica papaya
Papaya
0
Casuarina epuisetifolia
Australian pine
0-A
Cycas circinalis
Queen sago
R
Ficus aurea
Strangler fig
0
Laeuncularia racemosa
White mangrove
X
Roystonea sp.
Royal palm
X
Sabal palmetto
Cabbage palm
0
Schinus terebinthifolius
Brazilian pepper
LC -C
Thespesia populnea
Seaside mahoe
0
Washinetonia robusta
Washington palm
R
Herbs and Ground Covers
Bidens Pilosa
Begger-ticks C
Catharanthus roseus
Madagascar periwinkle 0
Cereus sp.
X
Cereus undatus
Night -blooming cereus R
Cissus trifoliata
Sorrel vine C
Ipomea batatus
Sweet potato X
Kalanchoe sp.
Mother of thousands R
3-4
FIND.17[WP]640-3-2.2
02/08/91
Table 3-2. Vegetation Species by Community Type Found at the MSA 640
Proposed Dredged Material Disposal Site, Palm Beach County,
Florida (Page 2 of 2)
Species Common Name Occurrence
Melothria pendula
Creeping cucumber
0
Momordica sp.
Balsam apple
R
Nephrolepis multiflora
Asian sword fern
LC
Nephrolepis sp.
Boston fern
LC
Parthenocissus quinquefolia
Virginia creeper
R -O
Philodendron sp.
Philodendron
LC -O
Poinsettia cyathophora
Painted -leaf
R -O
Rhoeo spathacea
Oyster plant
LC
Sansevieria thvrsiflora
Bowstring hemp
LC
Stenotaphrum secundatum
St. Augustine grass
LC
Tradescantia tricolor
Wandering jew
LC
DISTURBED LANDS (740)
Trees and Shrubs
Ficus aurea Strangler fig x
Sabal palmetto Cabbage palm R-0
Washinetonia robusta Washington palm C
Herbs and Ground Covers
Catharanthus roseus Madagascar periwinkle R -O
Chamaesvice hirta Hairy spurge 0
CyRerus sp. Sedge R
Dactyloctenium aegypti Crowfoot grass 0
Lippia nodiflora Frog fruit A
Poinsettia cyathophora Painted -leaf R
Stenotaphrum secundatum St. Augustine grass A
Occurrence:
A v Abundant; C v Common; LC e Locally Common; 0 — Occasional; R — Rare;
X — Trace.
Source: WAR 1990.
3-5
FIND.17(WP)640-3-0.6
02/08/91
3.5 DISTURBED LAND (740)
Along the southern portion of Site MSA 640 is an area that was cleared prior
to February 1986. Aerial photographs taken at that time show a newly cleared
portion of the site with little vegetation cover.
Existing vegetation consists of grasses and low -growing herbs that tolerate
regular mowing. Common species observed include St. Augustine grass, frog
fruit, crowfoot grass, and hairy spurge. A number of Washington palms have
been planted in the area and a few cabbage palms occur there as well.
3.6 ROADS AND HIGHWAYS (814)
A dirt road enters the site from the unimproved parcel to the west. This
cover type is unvegetated and the road surface consists of sand.
3.7 ENDANGERED AND THREATENED PLANTS
The endangered and threatened plants that may occur at Site MSA 640 are listed
in Table 3-3. Only one state endangered and threatened plant was found on
Site MSA 640. Night -blooming cereus was observed within the Australian pine
community. It is likely that this plant originated from ornamental stock that
was introduced to this site. A variety of escaped ornamental plants dominate
this site. Another species of Cereus was observed as well. It could not be
identified to species, but the evaluation of a sterile sample has eliminated
the possibility of it being tree cactus, a state and federally endangered
plant.
E,
FIND.17[WP]640-3-3.1
02/06/91
Table 3-3. Status of State or Federally Listed Endangered and Threatened
Plants That May Occur at the MSA 640 Proposed Dredged Material
Disposal Site, Palm Beach County, Florida
Species
Status
State FCREPA Federal
Cereus robinii E E E,II
Tree cactus
Cereus undatus * T II
Night -blooming cereus
Phlebodium aureum T
Golden polyplody
Tillandsia fasciculata CE
Common wild pine
Tillandsia flexuosa T
Twisted wild -pine
Tillandsia simulata T T
Wild pine
* confirmed on site
State: Florida Department of Agriculture; E = Endangered; T = Threatened;
CE — Commercially exploited.
FCREPA: Florida Committee on Rare and Endangered Plants and Animals
(Unofficial); E — Endangered; T — Threatened.
Federal: United States Fish and Wildlife Service; E — Endangered.
Convention on International Trade in Endangered Species of Wild
Fauna and Flora; II — Appendix II species.
Source: FGFWFC 1990.
Nesmith 1990.
WAR 1990.
3-7
4.0 WILDLIFE COMMUNITIES
FIND.17[WP]640-4-0.1
02/08/91
4.0 WILDLIFE COMMUNITIES
Table 4-1 lists species of wildlife observed during field surveys and
identifies habitats in which they were observed. Wildlife habitats on site
include all of the communities listed in Table 3-1.
4.1 WILDLIFE HABITAT
The wildlife value of this site is moderately poor. Site MSA 640 is small,
bordered on two sides by residential areas, and is covered by non-native
plants that provide few food resources for wildlife. However, thick
vegetation provides good cover for wildlife, and the proximity to both the
ICWW and an undeveloped parcel containing better wildlife food resources tend
to offset some of the poor wildlife habitat characteristics of the site.
The site provides some habitat for reptiles and amphibians. The Cuban
treefrog, squirrel treefrog, and southern toad are likely to be found in low
numbers on the site. Ground skinks may be found in the Australian pine
litter.
Mammals that may utilize the upland habitats include raccoon, armadillo, and
opossum. Mice and rats may also be found commonly in these areas. Birds
common in suburban areas were observed in the tree canopy. These include
northern cardinal, mockingbird, and red -bellied woodpecker. A variety of
other birds such as common crow, bluejay, and common grackle may occur on the
site. Some migrants such as yellow-rumped warbler, and black and white
warbler will use Australian pine canopies, but not to the same extent as
native woodlands. Because most of the tree canopy consists of Australian
pine, food resources for birds are seriously limited.
The shoreline drops off sharply into the ICWW and discourages the formation of
fringing, emergent wetlands used as foraging habitat by wading birds.
Foragers that may take advantage of a variety of small fish in the ICWW
include osprey, pelican, and cormorant.
4-1
FIND.17[WP]640-4-1.1
02/08/91
Table 4-1. Vertebrates and Invertebrates Observed at the MSA 640
Proposed Dredged Material Disposal Site, Palm Beach County,
Florida
Scientific Name
REPTILES AND AMPHIBIANS
Anolis s. san¢rei
BIRDS
Cardinalis cardinalis
Melaneroes carolinus
Mimus nolyclottos
Polioptila caerulea
INVERTEBRATES
Cardisoma Raunhumi
* 437 — Australian pine
Source: WAR 1990.
Common Name
Vegetation
Community
Cuban anole 437
Northern cardinal 437
Red -bellied woodpecker 437
Mockingbird 437
Blue -gray gnatcatcher 437
Great land crab 437
4-2
FIND.17[WP]640-4-0.3
02/08/91
Burrows of the great land crab were observed along the sandy, steeply sloped
banks bordering the ICWW.
4.2 ENDANGERED AND THREATENED ANIMALS
Table 4-2 lists protected species that are, or may be found at the MSA 640
proposed dredged material disposal site or adjacent waters. Various protected
birds, such as herons, egrets and wood stork may find limited perching and
foraging habitat in the estuarine waters of the ICWW. In addition, least
tern, pelican, and osprey utilize the waters of the ICWW for foraging.
Manatees and sea turtles may move through the waters of the ICWW. However good
foraging opportunities for these species do not occur near Site MSA 640
because of the lack of submerged aquatic vegetation.
Migrating raptors that may forage over terrestrial and/or aquatic habitats
include American kestrel, Cooper's hawk, merlin, and peregrine falcon.
4-3
FIND17[WP]640-4-2.1
02/08/91
Table 4-2. Status of State or Federally Listed Endangered or Threatened
Wildlife That May Occur on the MSA 640 Proposed Dredged Material
Disposal Site, Proposed Pipeline Access, or Adjacent Waters, Palm
Beach County, Florida (Page 1 of 2)
Species
REPTILES AND AMPHIBIANS
Caretta caretta
Atlantic loggerhead turtle
Chelonia m das
Atlantic green turtle
BIRDS
Accioiter coonerii
Cooper's hawk
Bueto brachvurus
Short -tailed hawk
Casmerodius albus
Great egret
E rg etta caerulea
Little blue heron
EQretta thula
Snowy egret
E rg etta tricolor
Tricolored heron
Eudocimus alba
White ibis
Falco columbarius
Merlin
Falco Pere rims
Perigrine falcon
Falco sparverius Paulus
Southeastern kestrel
Status
State FCREPA Federal Occurrence
T T
T,I
OV
E E
E,I
OV
4-4
SSC
OV
R
OV
SSC
OV
SSC
SSC
OV
SSC
SSC
OV
SSC
SSC
OV
SSC
OV
II
OV
E
E
T
OV
T
T
C2, II
OV
4-4
FIND17[WP]640-4-2.2
02/08/91
Table 4-2. Status of State or Federally Listed Endangered or Threatened
Wildlife That May Occur on the MSA 640 Proposed Dredged Material
Disposal Site, Proposed Pipeline Access, or Adjacent Waters, Palm
Beach County, Florida (Page 2 of 2)
Status
Species State FCREPA Federal Occurrence
Falco soarverius soarverius II OV
American kestrel
Pandion haliaetus T II OV
Osprey
Pelecanus occidentalis SSC T OV
Brown pelican
Sterna antillarum T OV
Least tern
K"Y-4I;M1F�
Trichechus manatus E T E,I OV
West Indian manatee
* Confirmed on site
State: Florida Game and Fresh Water Fish Commission; E — Endangered; T —
Threatened; SSC = Species of Special Concern.
FCREPA: Florida Committee on Rare and Endangered Plants and Animals
(Unofficial); E — Endangered; T — Threatened; SSC — Species of
Special Concern; R — Rare.
Federal: United States Fish and Wildlife Service: E — Endangered;
T — Threatened; C2 — A candidate for federal listing, with some
evidence of vulnerability, but for which not enough data exists
support listing.
Convention on International Trade in Endangered Species of Wild
Fauna and Flora; I — Appendix I species; II — Appendix II species.
Occurrence Code: OV — Occasional Visitor (migrants, accidentals, or may be
within part of home range of this species).
Source: FGFWFC 1990.
Nesmith 1990.
WAR 1990.
4-5
5.0 WETLAND JURISDICTIONS
FIND.17[WP]MSA640-5.1
02/08/91
5.0 WETLAND JURISDICTIONS
There are no wetlands located within Site MSA 640. There are a few scattered
fringing mangroves located along the ICWW; however, they consist of a
discontinuous band along a steeply sloped shoreline.
5-1
6.0 PIPELINE ACCESS
FIND.17[WP]MSA640-6.1
02/08/91
6.0 PIPELINE ACCESS
The pipeline will enter the disposal site directly from the ICWW located to
the east. It may cross through a patchy mangrove margin that borders the ICWW
on Site MSA 640.
6-1
7.0 REFERENCES
FIND.17[WPJMSA610-7.1
02/08/91
7.0 REFERENCES
Ashton, R.E. Jr. and R.S. Ashton. 1978, 1981, 1982. Handbook of Florida
Amphibians and Reptiles Vols. I -III. Windward Publishing, Miami, Florida.
Bromwell and Carrier, Inc. 1989. Phase One: Long-range Dredged Material
Management Plan Atlantic Intracoastal Waterway, Palm Beach County,
Florida. Lakeland, Florida.
Florida Department of Transportation (FDOT). 1985. Florida Land Use, Cover
and Forms Classification System. FOOT, State Topographic Bureau,
Tallahassee, Florida.
Florida Game and Fresh Water Fish Commission (FGFWFC). 1990. Official Lists
of Endangered and Potentially Endangered Fauna and Flora in Florida.
Compiled by Don A. Wood.
Florida Natural Areas Inventory and Florida Department of Natural Resources.
1990. Guide to the Natural Communities of Florida.
Kale, H.W. (ed.) 1978. Rare and Endangered Biota of Florida, Volume II,
Birds. Florida Committee on Rare and Endangered Plants and Animals,
University Presses of Florida, Gainesville, Florida.
Kale, H.W. and D.S. Maehr. 1990. Florida's Birds. Pineapple Press,
Sarasota, Florida.
Layne, J.N. (ed.) 1978. Rare and Endangered Biota of Florida, Volume I,
Mammals. Florida Committee on Rare and Endangered Plants and Animals,
University Presses of Florida, Gainesville, Florida.
Long, R.W. and 0. Lakela. 1971. A Flora of Tropical Florida. University of
Miami Press, Coral Gables, Florida.
McCollum, S.H., O.E. Cruz, L.T. Stem, W.H. Wittstruck, R.D. Ford and F.C.
Watts. 1978. Soil Survey of Palm Beach County Area, Florida. United
States Department of Agriculture, USDA Soil Conservation Service.
McDiarmid, R. (ed.) 1978. Rare and Endangered Biota of Florida, Volume III,
Amphibians and Reptiles. Florida Committee on Rare and Endangered Plants
and Animals, University Presses of Florida, Gainesville, Florida.
Nesbitt, S.A., J.C. Ogden, H.W. Kale III, P.W. Patty and L.A. Rowse. 1982.
Florida Atlas of Breeding Sites for Herons and Their Allies: 1976-78.
FWS/OBS-81/49.
Nesmith, K. 1990. Personal Communication. Florida Natural Areas Inventory,
Tallahassee, Florida.
7-1
FIND.17[WP]MSA610-7.2
02/08/91
Sprunt, A., Jr. 1954. Florida Bird Life. Coward -McCann, Inc., and National
Audubon Society.
Stevenson, H. 1976. Vertebrates of Florida, Identification and Distribution.
University Presses of Florida, Gainesville, Florida.
Water and Research, Inc. (WAR). 1990. Collected Data. Gainesville, Florida.
7-2
Management Plan
MSA 640/640A Disposal Area
March, 1992
Management Plan
MSA 640/640A Disposal Area
Prepared For:
FLORIDA INLAND NAVIGATION DISTRICT
by:
R. Bruce Taylor
William F. McFetridge
Taylor Engineering, Inc.
9086 Cypress Green Drive
Jacksonville, Florida 32256
(904) 731-7040
TABLE OF CONTENTS
LIST OF FIGURES ................................................. iii
1.0 INTRODUCTION ............................................. 1
2.0 PRE -DREDGING SITE PREPARATION AND DESIGN FEATURES ...........
4
2.1 Site Design ..............................................
4
2.1.1 Site Capacity ........................................
4
2.2 Site Preparation ..........................................
4
2.3 Additional Design Features ...................................
7
2.3.1 Inlet ..............................................
7
2.3.2 Ponding Depth .......................................
8
2.3.3 Weirs .............................................
9
2.3.4 Interior Earthworks ...................................
13
2.3.5 Ramps ............................................
14
2.3.6 Perimeter Ditches .....................................
14
2.3.7 Dike Erosion and Vegetation ..............................
15
2.3.8 Site Security ........................................
15
3.0 OPERATIONAL CONSIDERATIONS DURING DREDGING ................ 17
3.1 Placement of Pipelines ...................................... 17
3.2 Inlet Operation ........................................... 18
3.2.1 Monitoring Related to Inlet Operation ....................... 19
3.3 Weir Operation ........................................... 20
3.4 Monitoring of Effluent ...................................... 22
3.5 Groundwater Monitoring .................................... 23
4.0 POST -DREDGING SITE MANAGEMENT ............................. 25
4.1 Dewatering Operations ...................................... 25
4.2 Gradin the Deposition Material ............................... 27
4.3 Material Rehandling/Reuse................................... 28
4.4 Monitoring of Containment Area Performance ...................... 29
I
TABLE OF CONTENTS CONT...
4.5 Continuing Monitoring Requirements ............................ 30
4.6 Mosquito Control ......................................... 30
4.7 Site Security ............................................. 32
REFERENCES ............................................... 33
ii
LIST OF FIGURES
Figure 1-1: Location of FIND MSA 640/640A Dredged Material Disposal Site, Palm Beach
County, Florida ......................................... 2
Figure 2-1: Disposal Area Site Plan, Site MSA 640/640A, Palm Beach County, Florida .... 5
Figure 2-2: Typical Dike and Ramp Sections, Vegetation Plan, Site MSA 640/640A, Palm
Beach County, Florida ..................................... 6
Figure 2-3: Zone Settling Velocity of Intracoastal Waterway Channel Sediments ........ 12
Figure 4-1: Disposal Area Vegetation Map Site MSA 640/640A, Palm Beach County,
Florida.............................................. 31
iii
1.0 INTRODUCTION
A key element in the long-term utilization of any dredged material containment site is the
development and implementation of a site-specific management plan. The management plan for Site
MSA 640/640A, outlined in this report, is intended to provide guidance for the development and
operation of the containment area so that optimum efficiency is achieved in both effluent quality and
containment area service life while minimizing the impact of the site on the environment and adjacent
areas. Addressed are those facets of site design and operation which directly influence site efficiency or
reduce off-site conflicts. These include elements of site preparation prior to the initial dredging and
deposition of maintenance material, techniques of decanting and dewatering the maintenance material
during and immediately following a maintenance event, and criteria for post -dredging site operation and
maintenance. Throughout, the goal of each aspect of site management is to assure that the site not only
achieves its minimum design 50 -year service life, but that it also fulfills its potential as a permanent
operating facility for the intermediate storage and re -handling of maintenance material dredged from the
Intracoastal Waterway (ICWW).
Site MSA 640/640A (Figure 1-1) is one of eight maintenance material containment sites selected
to provide long-term dredged material containment capacity for the Intracoastal Waterway (ICWW) in
Palm Beach County, Florida. Specifically, Site MSA 640/640A comprises two contiguous parcels
owned by the Florida Inland Navigation District. It is intended to serve that portion of the ICWW
designated as Reach IV by Taylor (1990), extending 18.50 miles from the Vicinity of Lantana (S.R. 812
Bridge) (ICWW mile 291.72) to the southern county line (ICWW mile 310.22). Records of the
Jacksonville District Corps of Engineers indicate that no maintenance dredging has been performed
within this reach since the establishment of the 10 foot project depth in 1966. However, 1987 and 1988
reconnaissance surveys revealed the presence of excessive shoaling in several locations. Based on this
information, the projected 50 year containment requirement of the reach is approximately 158,000 cubic
yards (cy)(Bromwell and Carrier, Inc., 1989). The total site area of MSA 640/640A is 7.09 acres, of
which approximately 2.63 acres will lie outside of the containment dike. Vegetation in portions of this
area adjacent to the property boundaries will remain undisturbed, providing a natural buffer zone along
the site perimeter. The projected initial site containment capacity of 18,382 cubic yards (cy) is adequate
to meet twelve per cent of the 50 -year reach containment requirement. The remaining eighty-eight per
cent of the required capacity will be obtained by utilization of two other sites, MSA 641A and MSA
684A, and a beach nourishment area south of Boynton Inlet (Taylor, 1990).
_ TAYLOR ENGINEERING INC
9086 CYPRESS GREEN DRIVE
JACKSONVILLE, FLORIDA 32256
80°0230° o
I —r4i
0
N
ISPOSAL
ITE MSA 640/640A
80°02'30°
0 1L
2000,
Faure I - I
Location of FIND MSA 640/640A
Dredged Material Disposal Site
Palm Beach County, Florida
As stated above, beyond satisfying an initial capacity requirement, the management objectives for
MSA 640/640A are to efficiently process (i.e. decant and dewater) the dredged material, and to operate
the facility so as to extend its usefulness beyond the design service life. The potential long-term
efficiency of the containment area is established by the design and construction of the facility, while the
degree to which this potential is realized is largely determined by operating procedures. Specific
elements of site design and site operation during and following disposal activity will be discussed in turn
as they relate to site efficiency and local impacts. However, design features and construction practices,
beginning with site preparation, provide the foundation for the project, both physically and figuratively,
and should therefore reflect the level of effort that has gone into the selection of Site MSA 640/640A, as
well as the substantial long-term commitment of state and federal funds that this project represents. The
plan document begins in Section 2.0 with a discussion of site preparation and design. Site operational
considerations during dredging are discussed in Section 3.0. Post -dredging site management is addressed
in Section 4.0.
2.0 PRE -DREDGING SITE PREPARATION AND DESIGN FEATURES
2.1 Site Desien
No attempt will be made here to address, in detail, all elements of site design. These are
described elsewhere in the permit documentation. Rather, the present discussion will be limited to those
aspects of site design which directly influence site operation and maintenance.
2.1.1 Site Capacity
The 50 year disposal requirement of Reach II is 158,000 cy, based on present patterns of
shoaling, (Bromwell and Carrier, Inc., 1989). As stated in Section 1.0, the projected disposal capacity
of Site MSA 640/640A is approximately 18,382 cy. To obtain this capacity within the 4.46 acre dike
footprint, it is necessary to construct containment dikes to a crest elevation of 6.0 ft (+12.07 ft NGVD)
above the existing mean site elevation of +6.07 ft NGVD (Figures 2-1, 2-2). Based on a conservative
dike cross-sectional design including side slopes of 1V:3H and a crest width of 12 ft, 10,822 cy of
material are required to construct the dikes. An additional 603 cy are required for ramps to provide
equipment access to the interior of the containment basin. When the containment basin is filled to
capacity, the surface of the deposition layer will be a minimum of 4.0 ft below the dike crest, thereby
providing an additional 2.0 ft of freeboard and 2.0 ft of ponding depth.
2.2 Site Preparation
Site preparation required for the MSA 640/640A disposal area will include the clearing of
vegetation, and the alteration of the existing topography within the proposed containment area prior to
dike construction. Historically, containment area construction has often been accomplished without any
interior site preparation. Moreover, it is recognized that clearing and grubbing vegetation and uniformly
excavating and grading the site interior adds significantly to the initial construction cost of the facility,
and should not be undertaken without the expectation of significant benefits. However, it is felt such
measures are warranted in the present situation. Regarding the clearing of vegetation, it has been
established (Haliburton, 1978; Gallagher, 1978) that although a limited growth of herbaceous vegetation
or native grasses can improve sedimentation by filtration, woody vegetation (i.e. brush and small trees)
can constrict or channelize the flow through the containment basin, resulting in short-circuiting, reduced
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retention times, resuspension of sediment through increased flow velocities, and the deterioration of
effluent quality. Additionally, failure to clear existing vegetation will result in an increase in the organic
content of the fill, rendering it less suitable for removal and re -use as construction grade material.
Therefore, the containment area should be cleared and grubbed prior to construction.
Similarly, the existing topography within the containment area, if allowed to remain will cause
the flow from inlet to weir to channelize. This would lead to a reduced effective sedimentation area,
increased flow velocities, and again, decreased solids removal efficiency. Moreover, irregular
topography will produce irregular deposition, which, in turn, will result in the ponding of surface water,
thereby inhibiting the drying of the deposition layer and making initial attempts at surface trenching
more difficult. For these reasons, it is important that a uniform grade be provided from inlet to weir as
part of the initial construction of the facility, with an adequate slope on the order of 0.2 per cent. It is
also recognized that given an initially level surface, differential settling of varying grain size fractions
(i.e., rapid precipitation of the coarser fractions nearer the inlet with increasingly finer sediments
deposited nearer the outlet) will quickly establish a deposition surface sloping downward from inlet to
weir once disposal operations begin.
Preliminary site design assumes that most of the material for dike construction will be obtained
from the excavation of the containment area interior. To provide the volume of material required to
construct the dike it will be necessary to excavate 3.20 ft below the existing grade to an average
elevation of +2.55 ft NGVD, allowing for a 20 ft excavation setback from the interior toe of the dike.
Limited data obtained at the time of the soil survey showed the on-site water table at a mean elevation of
+1.81 ft NGVD, or 0.74 ft below the excavation grade. Therefore, a sump and/or pumping of seepage
may be required during construction because of the close proximity of the groundwater surface to the
excavated basin interior grade.
2.3 Additional Design Features
2.3.1 Inlet
The location of the dredge discharge outfall, or pipeline inlet, within the containment basin is the
primary means of regulating the pattern of material deposition. The disadvantage of a single, fixed inlet
is the characteristic mounding of coarse material in the vicinity of the inlet, which if not mechanically
re -distributed, results in reduced retention area. However, the anticipated infrequent requirement for
maintenance dredging in this reach of the waterway cannot justify the cost of a fixed, multiple inlet
manifold system for the MSA 640/640A site. More appropriate is the use of a moveable single inlet
with the flexibility to be repositioned during disposal operations. The single inlet should also be fitted
with a device which breaks the momentum of the jet, such as a flow -splitter or a spoon, to aid in the
distribution of the slurry.
Preliminary analysis of the dredged material settling behavior within the MSA 640/640A disposal
area, discussed in Section 2.3.3, indicates that the maximum available distance between inlet and weir
may be required to meet effluent turbidity standards. Therefore, relocating the inlet must not result in a
significant reduction in the separation distance between inlet and outlet without the implementation of
additional precautions to ensure that water quality standards are met. These may include increasing the
ponding depth, or the use of floating baffles or turbidity screens surrounding the weirs.
2.3.2 Ponding Depth
Ponding depth refers to the height of the water column (with its suspended sediment load)
maintained above the depositional surface during dredging and disposal operations. Ponding depth is
regulated by the height of the weir crest, and to a lesser extent, by the dredge plant output. More of an
operational criterion than a design feature, ponding depth is nevertheless a primary design consideration,
impacting containment area and dike geometry, as well as weir design.
It is advantageous to maintain as great a ponding depth during disposal operations as possible.
Increased ponding depths produce increased retention times and decreased flow velocities through the
containment basin, and are therefore related to improved solids retention and effluent quality. The
limiting consideration for increased ponding depth is the unbalanced head, or hydrostatic pressure, which
the dike can withstand without compromising its structural integrity.
Preliminary design of the containment basin provides for a minimum 2 foot ponding depth plus 2
feet of freeboard when the containment basin reaches its maximum capacity. Analysis of containment
basin efficiency based on the anticipated characteristics of the sediment likely to be dredged indicates that
a ponding depth greater than the 2 foot minimum will be required to provide adequate retention time and
acceptable effluent quality. Therefore, it is recommended that ponding depths be maintained above the 2
foot minimum whenever possible.
The recommended operational ponding depth of MSA 640/640A is 4.0 ft, with a maximum depth
limitation of 5 ft. Care must be taken not to increase ponding depth above the 2 ft minimum too
quickly, a situation that may lead to dike saturation, piping, slumping, and other conditions of dike
instability. However, operational experience has demonstrated that if ponding depth is increased slowly,
or over a series of dredging events, the permeability of the interior dike slopes is reduced as fine
sediments are filtered and trapped by piping through the dike, thereby decreasing the probability of dike
failure. Operational experience has demonstrated that if ponding depth is increased sufficiently slowly,
the permeability of the interior face of the dike slope is reduced as fine sediments are filtered and
trapped by percolation, thereby limiting dike saturation and instability. Restricting ponding depths to the
5 ft maximum should preclude the occurrence of unstable dike conditions and provide a sufficient safety
factor to ensure efficient solids removal.
2.3.3 Weirs
The outlet control structures which maintain the necessary ponding depth, and subsequently the
retention time, consist of a system of weirs. In addition to controlling ponding depth, several aspects of
weir design strongly influence the efficiency of solids retention and the quality of effluent released from
the MSA 640/640A containment area. These include weir type, weir crest length, and the location of
the weirs within the containment area.
The type of weir structure to be employed at Site MSA 640/640A represents a compromise
between considerations of performance, adjustability, maintenance, and economy. A sharp -crested,
rectangular weir is specified to minimize the depth of withdrawal of the supernatant. Sharp -crested
means that the thickness of the weir crest (T) is small in comparison to the depth of flow over the weir
(h); typically h/T > 1.5. Rectangular indicates that the weir crest is straight, and that flow over the
weir is normal to the primary weir axis. Withdrawal depth is the depth to which the inertial forces on a
suspended sediment particle exceed the gravity forces. Reducing the depth of withdrawal to less than the
ponding depth reduces the possibility of resuspending sediment which has settled out of the water
column. Moreover, since the concentration of suspended sediment increases with depth, minimizing the
L"
depth of withdrawal maximizes the retention of solids. Specific expected performance characteristics of
the MSA 640/640A weir system are discussed later in this section.
The minimum weir crest length for Site MSA 640/640A is 24 ft. This specification is based on
results obtained from the Selective Withdrawal Model developed by the U.S. Army Corps of Engineers'
Waterways Experiment Station (WES), and represents the weir crest length required to maintain a depth
of withdrawal which is less than the minimum ponding depth of 2.0 ft. For this and all succeeding
calculations of basin hydraulic characteristics, it has been assumed that a 18 inch O.D. dredge (discharge
velocity, 16 ft/sec; volumetric discharge, 3,560 cy/hr; 20/80 solids/liquid slurry mix) would be used for
future maintenance. This assumption is based on recommendations by the Jacksonville District Corps of
Engineers. The 24 foot minimum length will be provided by three corrugated metal half -pipes, each
with a sharp -crested 8 ft weir section. The three pipes will be connected by a common manifold such
that the effluent will exit the containment area via a single pipe under the dike.
The height of the weir crest is adjustable by means of removable flashboards. The minimum
elevation of the weir crest, +2.10 ft NGVD, will be equivalent to the minimum interior grade elevation,
which occurs in the vicinity of the weirs. This provides a means of releasing ponded run-off prior to the
initiation of disposal operations. The maximum elevation of +9.71 ft NGVD, or 6.90 ft above the
mean excavated grade (3.64 ft above the mean existing site elevation), allows 2.0 ft of freeboard below
the dike crest at the maximum capacity of the containment basin. The flashboards will be made of 4 x 4
stock, interlocked by tongue -and -groove to provide rigidity against hydrostatic pressure, and to minimize
between -board seepage of water with a higher suspended sediment concentration. The use of a
flashboard width of 3 inches (after milling) assures that the minimum adjustment increment will be less
than the projected depth of flow over the weir crest (4.3 inches) during disposal operations after the
maximum ponding depth has been attained. At this point the weir discharge approximately equals the
liquid inflow to the containment area. In this manner the operator is provided with adequate adjustment
resolution to maximize weir performance and effluent quality.
Analysis of weir performance based on nomograms developed at the Waterways Experiment
Station under the Dredged Material Research Program (Walski and Schroeder, 1978) indicates that these
design parameters may be expected to produce an effluent suspended sediment concentration of 0.45 g/1,
assuming an average ponding depth of 2 ft. Increasing ponding depth above this level, as recommended,
should result in a further improvement in effluent quality. Translation of suspended solids concentration
10
to a measure of turbidity on which Florida water quality standards are based is highly dependent on the
suspended material characteristics. However, WES guidelines (Palermo, 1978) indicate that this effluent
quality should be adequate.
The final weir design parameter which was considered is the location of the weirs within the
containment area to maximize the distance from the dredge pipe inlet and minimize the return distance to
the receiving waters. The latter requirement is needed to facilitate the flow of effluent out of the
containment area by gravity. As shown in Figure 2-1, the weirs will be located in the southeast corner
of the containment basin, providing approximately 455 ft from inlet to weir.
Using the above described weir locations, an analysis of containment area efficiency was
performed. However, no data characterizing channel sediments in the reach served by the proposed
MSA 640/640A disposal area are available. Therefore, it was assumed that the sediment to be
encountered within this reach includes up to 25 per cent silt, capable of passing a //200 sieve. This
estimate is supported by the experience of the Jacksonville District Corps of Engineers and is considered
to be conservatively high. With this assumption, an associated zone settling velocity was then
determined from an empirical relationship between silt content and settling behavior developed from
Corps of Engineers sediment data characterizing a variety of ICWW channel sediments (Figure 2-3:
Taylor and McFetridge, 1989). The resulting zone settling velocity for the sediment to be placed in Site
MSA 640/640A was determined to be 0.50 cm/min. This settling velocity was then used to determine
the retention time needed to provide adequate sedimentation within the containment basin.
Analysis of the hydraulic characteristics of the proposed containment basin under equilibrium
flow conditions indicates that a 2.0 foot ponding depth will provide a maximum retention time of 3.03
hrs. By comparison, the time required for the sediment to settle out of the withdrawal layer of 2.0 ft is
2.03 hrs based on the zone settling velocity derived above. However, research by the Army Corps of
Engineers Waterways Experiment Station (WES) under the Dredged Material Research Program
(DMRP) (Shields, Thackston and Schroeder, 1987) indicates that the required settling time of the
dredged material should be multiplied by a correction factor of 2.25 to account for anticpated conditions
in the field. Thus, the corrected settling time of 4.57 hrs exceeds the computed maximum basin
retention time of 3.03 hours produced by the minimum ponding depth of 2 ft. It is therefore
recommended that the ponding depth within the basin be maintained at or above 4 ft at all times during
L.zt
1--
L50
U
1.25
LV
(D 1.0
_Z
J
0.75
W
U)
W 0.50
Z
O
N 0.25
0.0
0 10 20 30 40 50 60 70 80 90 100
PERCENT FINER THAN N0. 200 SIEVE
TAYLOR ENGINEERING INC
9086 CYPRESS GREEN DRIVE
JACKSONVILLE, FLORIDA 32256
Figure 2-3 Zone Settling Velocity
of ICWW Sediments as a Function of
Silt Content (Taylor and McFetridge,
1989)
12
2.3.5 Ramps
Ramps to provide heavy equipment access to the containment area interior have been integrated
into the design of the containment dike (Figure 2-2). This was done to provide the capability of
efficiently removing the dewatered dredged material as containment capacity needs dictate. Thus, the
disposal site is designed to function more as a material processing and rehandling station than as a
permanent storage facility. In this manner, the useful service life of the site may be extended
indefinitely.
The ramps themselves obliquely traverse the containment dike, maintaining the same 1V:3H side
slope as the dike. The recommended ascending/descending grade is 5 per cent, with a road surface
width of 12 ft. The ramps are positioned to facilitate the entry and exit of heavy equipment via a
connection to Federal Highway (U.S. 1) near the southwestern corner of the site (Figure 2-1). In
addition to providing for material removal, the ramps also allow easy entry for equipment to be utilized
in the dewatering process. This is discussed in Section 3.0.
2.3.6 Perimeter Ditches
The migration of saltwater from the interior of the containment basin into the on-site shallow
aquifer is not expected to be a significant problem because of the relatively infrequent periods of short
duration in which saltwater will be present on-site, and because of additional facility design precautions
described here. As discussed elsewhere in this report, ponded saltwater will be present within the
containment area only during actual dredging operations and for a short period immediately following
dredging to allow the clarified effluent to be released back to the ICWW. Such periods are expected to
last approximately four to six weeks, at a frequency of once every 10 to 12 years. Notwithstanding this,
as an added precaution to ensure that the horizontal migration of saltwater on-site is contained at or near
the diked area, a system of ditches will be constructed around the outer perimeter of the dike. These
ditches will surround the landward sides of the containment area, thereby inhibiting the horizontal
migration of water. The ditches will also serve to control the flow of storm runoff from portions of the
site outside of the containment basin. In addition, as discussed. in Section 3.5, shallow wells placed
within the site buffer area will be monitored prior to, during, and following dredging operations to
detect any potential saltwater migration from the dike area. Should elevated chloride levels be observed
14
in the well samples during dredging operations, pumping will be ceased immediately and the ponding
depth within the basin will be decreased.
The perimeter ditches are to be constructed at a 20 ft setback from the outside toe of the
containment dike. To effectively intercept saltwater migration during the initial dredging operation, the
ditch invert must be at or below the adjacent excavated interior grade of the containment basin.
Therefore, the elevation of the ditch bottom will coincide with that of the basin interior. The ditches are
to have a IV: 1H sideslope and a bottom width of 3 ft. Preliminary analysis indicates that a minimum
depth of 2.8 ft will provide adequate conveyance for the 25 year storm runoff from the contributing
drainage area, consisting of the exterior face of the containment dike, the perimeter road, and limited
portions of the buffer area adjacent to the ditches. Control and conveyance of storm runoff from within
the containment basin will be discussed in Section 4.2.1.
2.3.7 Dike Erosion and Vegetation
The stability of the containment dike must also be protected against erosion from rainfall runoff,
and wind. This will be accomplished by vegetating the dike slopes and crest immediately following dike
construction (Figure 2-2). Native grasses will be used (including, but not limited to Paspalum
vaginatum) which quickly form soil binding mats while not rooting so deeply so as to structurally
weaken the dike. Planting will be on maximum 18 inch centers using nursery stock (slips) to ensure
rapid coverage. As an alternative, seeding may be preferred to the use of slips if the scheduling of
construction and maintenance operations provides the additional time required for the vegetation to
become established. In addition to stabilizing the containment dike against erosion, vegetation will also
reduce the visual impact of the containment area.
2.3.8 Site Security
Security should be provided appropriate to the commitment of public funds that this project
represents. Permanent security fencing will be erected around the site perimeter during the initial phase
of construction to control public access to the containment dike and interior. Access to this portion of
the site will be controlled by locked gates. Keys to these gates will be held by FIND and distributed on
an as needed basis to agents of the COE, dredging contractors, and other authorized parties.
15
In addition, on-site operators should be present at all times during active disposal operations, and
decanting operations following a dredging event, or at any time when significant ponded water remains
within the containment area. This is to ensure the proper operation, adjustment, and maintenance of the
weirs, as well as to prevent the premature release of effluent through unauthorized weir operation.
Active on-site operations will be discussed in more detail in Section 3.0.
16
3.0 OPERATIONAL CONSIDERATIONS DURING DREDGING
The primary objectives of site management during disposal operations are: (1) to maintain
acceptable effluent quality during the decanting process; and, (2) to maximize the dewatering rate of the
deposited material by controlling the pattern of deposition. To this end, four elements of site
management are discussed. The first addresses the placement and handling of pipelines to and from the
containment area. The second examines the operation and monitoring of the containment area inlets.
Site operational guidelines and procedures included here are intended to promote the efficient utilization
of the containment area, and to facilitate the achievement of effluent water quality standards. The third
site management consideration addressed, and the one most critical for determining the quality of
effluent released from the disposal site, is weir operation. Lastly, a monitoring program is presented to
ensure that the operation of the containmentarea does not degrade the shallow aquifer groundwater in
the immediate vicinity of the disposal site.
3.1 Placement of Pipelines
Each maintenance and disposal operation over the design life of the MSA 640/640A disposal site
will require the placement and retrieval of a supply pipeline. The route to be used for this purpose is
shown in Figure 2-1. The supply pipeline will enter the site approximately 30 ft south of the northern
site boundary. It will parallel the perimeter ditch, lying between the ditch and the perimeter road along
the northern side of the containment dike. At the northwest corner of the containment dike, the supply
pipeline will pass over the dike crest and enter the basin. Due to the infrequent need for maintenance
dredging in this reach, it is not feasible from the standpoint of economy to allow the supply pipeline to
remain in place between dredging events. Therefore, following the completion of dredging, it will be
removed.
A return pipeline will connect to the weir/manifold system at the point at which it exits under the
dike in the southeast comer of containment basin, and continue eastward a distance of approximately 60
ft to the ICWW. The return pipeline will remain in place to provide a permanent means of draining
ponded rainwater from the interior of the containment area. Utilization of the weir system to control
stormwater runoff will ensure that at any suspended sediment is retained. The removal of run-off is
discussed further in Section 4.2.1.
17
3.2 Inlet Operation
The manner in which the inlet pipe is operated will be primarily determined by the quality of the
sediment to be dredged. Previous estimates of containment area solids retention performance have been
based on information concerning the general characteristics of channel sediments likely to be present in
this reach. Although this information may provide a valid indication of the general quality of sediment
to be encountered, more specific information must be obtained prior to future maintenance operations.
These data will include, at a minimum, core boring logs and a qualitative categorization of each strata of
sediment, laboratory data including sediment size distribution curves and/or Atterberg limits, and
suspended sediment -settling time curves from each boring location.
Subject to this event -specific information which characterizes the quality of the sediment to be
dredged, the following strategy of inlet operation within the containment area is suggested. This
procedure is based on the characteristics of sediments common to this region, which include fine sand
with significant components of organic silt and clay. It makes no attempt to segregate material grain size
fractions by manipulating the inlet. Some segregation will occur naturally as a result of differential
settling behavior, with the coarsest fraction settling out of suspension very rapidly, forming a mound in
the area of the inlet. Successively finer fractions, characterized by lower settling velocities, will be
deposited closer to the outlet weirs. The position of the inlet will be moved during disposal operations,
but only to minimize the mounding of the coarser fraction of sediment, and to distribute the deposited
material more uniformly. For the MSA 640/640A disposal area, this will entail a progressive
southeasterly extension of the supply pipeline from the point where it enters the containment area,
resting each extension on the mound formed by the previous inlet position. A minimum distance of 50 ft
must be maintained between the inlet and the inside toe of the dike to preclude erosion or undercutting
of the interior dike slope. The resulting pattern of deposition will maintain a consistent slope from inlet
to weir, and will minimize dead zones and channelization.
An additional, although secondary, advantage to be gained through extending the inlet pipeline in
the above described manner comes as a result of the dredge plant being necessarily shut -down to allow
each extension section to be added. These operational intermissions, together with temporary shutdowns
to move the dredge, effectively increase the retention time of the containment area, thereby increasing
the solids retention efficiency of the basin. It should be noted, however, that a preliminary analysis of
18
containment area performance indicates that adequate effluent quality can be attained without requiring
intermittent dredge operation.
3.2.1 Monitoring Related to Inlet Operation
During active disposal operations, several monitoring procedures related to inlet operations will
be required. Ponding depth, as previously mentioned, is a critical parameter for the optimization of
containment area performance. It is desirable to maintain as great a ponding depth as possible, thereby
increasing retention time, solids retention, and effluent quality. However, unbalanced hydrostatic forces
resulting from too great a ponding depth under saturated foundation conditions can lead to slope
instability, slumping, and the potential for dike failure. Obviously, the latter situation must be avoided
at all costs. Therefore, ponding depth should only be increased above the 2 foot minimum under close
monitoring by visual inspection of dike integrity. Indications of impending instability include evidence
of foundation saturation and seepage at the outer dike toe, and small-scale slumping. If no effluent is
released at the weirs, the design dredge output (i.e., 3,560 cy/hr slurry at a 20/80 solids/liquid mix, or
2,848 cy/hr liquid) will produce an increase in ponding depth of 0.66 ft/hr, and a rise in the water
surface (i.e. deposition layer plus ponding) of 0.82 ft/hr. These rates are slow enough to allow close
continual monitoring of the entire dike perimeter. However, ponding depth should not be permitted to
increase beyond a maximum of 5 ft. Continuous monitoring of dike stability should be performed
during periods when ponding depth is maintained above the 2 foot minimum.
Optimal containment area operating efficiency requires that flow through the basin approximate
plug flow to the greatest degree possible, thereby minimizing the uneven distribution of flow velocities
and sediment re -suspension, and maximizing retention time. Therefore, the pattern of sediment
deposition should be monitored for indications of irregular distribution, channelization, and short-
circuiting. If evidence of such anomalies is found, the inlet pipe should be repositioned until a more
uniform depositional surface is formed.
Lastly, the dredge plant output should be periodically monitored at the slurry outfall within the
containment area throughout dredging and disposal operations. The object of this monitoring is to
confirm or refine dredge output specifications, including volumetric output and slurry solids content.
These parameters, in combination with the duration of actual dredge operation, can be used as an
independent measure of disposal volume for purposes of determining remaining site capacity.
W
Additionally, the computed disposal volume can be used with pre- and post -dredging bathymetric surveys
of the channel, and topographic surveys within the containment area following disposal and dewatering
of the deposition layer, to refine the bulking factor employed to translate in-situ dredging volume to
required disposal volume. Also, within the same monitoring program the quality of dredged sediment
should be examined by typical techniques of soils analysis including the establishment of grain size
distributions, settling velocities, specific gravity, and Atterberg limits, if appropriate. The results of this
monitoring and analysis, together with measures of effluent quality to be discussed in the following
section, provide a basis for the operational management of containment area performance and efficiency.
3.3 Weir Operation
Once the containment area is constructed and dredging and disposal operations have begun, the
most effective way to control effluent quality is by changing ponding depth and rate of flow over the
weir through adjustments in the weir crest elevation. Prior to the commencement of dredging, the weir
crest elevation should be set as necessary to prevent the early release of effluent. The minimum initial
elevation of the weir crest above the mean interior site grade should be equal to the recommended
operational ponding depth of 4 ft, minus the operational static head (i.e., the height of the water surface
above the weir crest) of 0.42 ft. For Site MSA 640/640A, this will result in an initial weir crest
elevation of +6.13 ft NGVD. The initial containment area interior slope of 0.2 per cent, results in the
elevation of the excavated grade at the weirs being 0.46 ft below the mean excavated grade of the basin
interior. Therefore, the initial height of the weir crest above the excavated grade at the weirs should be
approximately 4.04 ft.
Once dredging begins, the weir crest should be maintained at its initial elevation until the ponded
water surface approaches the weir crest. During this initial phase of operation in which no effluent is
released, the discharge of the dredge plant should result in an increase in ponding depth of
approximately 0.66 ft/hr, and an increase in the ponded water surface elevation (ponding depth plus
deposition layer) of less than 0.82 ft/hr. This relatively slow rise should allow for close continual
monitoring of the entire dike perimeter for indications of slope instability, as discussed in the previous
section. Inspection is most critical during the initial phase of operations, and during subsequent disposal
periods when the ponded water surface is raised above its previous maximum elevation. Experience has
shown that as the ponded water percolates into the interior dike slope, the fine suspended sediment is
911
filtered by the coarser dike material. This reduces the permeability of the dike and decreases the
susceptibility of the dike to piping and saturation.
As ponding depth increases above the recommended operational depth of 4 ft (approximately 4.46
ft at the weirs), the decision must be made to initiate release of the supernatant. It is important to note
that the weirs are only flow control structures and therefore cannot improve effluent quality beyond that
of the surface water immediately interior to the weir crests. Thus, the decision to release must be based
on the results of turbidity testing or suspended sediment concentration analysis conducted on the surface
waters inside the weirs. These tests must reflect conditions at the maximum depth of withdrawal. For
Site MSA 640/640A this was determined from recommended WES procedures to be 2.0 ft, based on a
design weir loading of 0.89 cfs/ft. If the desired water quality is achieved at a ponding depth less than
the recommended 4.0 ft, the water surface should still be permitted to rise to the weir crest provided that
dike integrity is not threatened. If adequate water quality is not achieved at the recommended
operational ponding depth, additional measures may be required prior to the release of effluent. These
may include allowing the ponding depth to increase to the maximum recommended 5.0 ft, installing
turbidity screens or floating baffles around the weirs, or requiring that the dredge plant be shut down
until the surface water turbidity reaches acceptable limits.
Once flow over the weirs has begun and effluent of acceptable quality is being produced, as
indicated by effluent sample analysis, the static head over the weir becomes the most readily used
criterion for weir operation. The static head represents the elevation of the water surface above the weir
crest as measured upstream of the weir at a point where velocities are small (1 to 2 per cent of the weir
loading rate). For a design weir loading of 0.89 cfs/ft, the operational static head has been calculated to
be 0.42 ft or 5.0 inches, based on an empirical relationship developed for sharp -crested weirs.
The actual operating head over the weir can be measured on site by two methods. First, it can be
determined by using a stage gauge, located in the basin where velocities caused by the weir are small (at
least 40 to 50 ft from the weir). The elevation of the water surface can be read directly from the gauge,
with the difference between the gauge elevation and the elevation of the weir crest indicating the static
head. The static head can also be determined indirectly by measuring the depth of flow over the weir.
The ratio of depth of flow over the weir to static head has been shown to be 0.85 for sharp -crested
weirs, yielding a design depth of flow for the MSA 640/640A facility of 0.36 ft or 4.3 inches. If the
head over the weir, as measured by either method, falls below these design values as a result of unsteady
21
dredge output or intermittent operation, effluent quality should increase. However, if the head exceeds
these values, the ponding depth should be increased by adding a flash board, or dredging should be
interrupted to prevent a decrease in effluent quality.
At all times, each of the three weir sections must be maintained at the same elevation to prevent
flow concentration and a decrease in effluent quality related to an increase in weir loading. It is also
important to prevent floating debris from collecting in front of the weir sections. This will result in an
increase in the effective depth of withdrawal and a corresponding increase in effluent suspended solids
concentration.
After dredging has been completed, the ponded water must be slowly released, allowing the flow
over the weir to drop essentially to zero before the next flash board is removed. Monitoring of effluent
quality should continue during this process. If turbidity violates water quality standards the effluent
must be retained until analysis of the interior surface waters indicates the suspended solids concentration
to be within acceptable limits. Because the time of retention is increased during this phase of decanting,
effluent quality is also expected to increase while the ponding depth remains above 2 ft. However,
because the concentration of the suspended sediment contained within the ponded water increases with
depth, unacceptable effluent turbidity may result as the ponded water is drawn down further. The
decanting process should then continue in this manner until all ponded water is released over the weirs.
Continued dewatering through progressive trenching and other post -dredging procedures is discussed in
Section 4.0.
3.4 Monitoring or Ernuent
The monitoring of effluent released from the MSA 640/640A disposal site will be an integral part
of the operation of the facility. The containment area has been designed to produce effluent which meets
the water quality standards for Class HI waters as set forth in Chapter 17-3 of the Florida Administrative
Code. These rules require that site compliance be documented by results obtained from a comprehensive
monitoring program. Therefore, the monitoring program should be in place at all times during active
disposal operations. The minimum recommended sampling frequency is two times per eight hour shift.
Although effluent turbidity is but one of 29 parameters addressed in the Florida state water
quality standards, compliance with these standards has been historically based on turbidity alone for
22
several reasons. To begin, turbidity can be reliably measured in the field, and is the only water quality
parameter over which the containment area operator may exercise direct control. Moreover, turbidity is
a strong indicator of general effluent quality since many contaminants, most notably the toxic metals,
exhibit a strong affinity for fine particles. Thus, reducing turbidity should result in an overall
improvement in effluent quality.
It is recognized, however, that the disturbance of contaminated sediments may result in the
release of other pollutants, predominantly nutrients and hydrocarbons, which do not necessarily associate
with fine particles. Thus, if the in-situ sediments contain elevated levels of these contaminants, turbidity
may be a superficial indicator of effluent quality. Monitoring of effluent should therefore be based on
the results of comprehensive elutriate and dry analysis of the sediment to be dredged prior to the
commencement of dredging. Testing required under the effluent monitoring program should then focus
on those contaminants whose presence in the sediment has been established.
Because effluent turbidity is a primary water quality parameter for disposal site operation,
compliance with turbidity standards will control both the dredge plant output and the release of effluent.
State turbidity standards are expressed in terms of nephelometric turbidity units (NTU), which measure
the optical transparency of the effluent relative to the optical transparency of the receiving water.
Containment area design guidelines published by the U.S. Army Corps of Engineers Waterways
Experiment Station (WES) under the Dredged Material Research Program (DMRP) relate containment
area performance to the suspended solids concentration of the effluent. The translation of solids
concentration (e.g. grams of suspended solids per liter of fluid) to a measure of turbidity is highly
dependent on the characteristics of the suspended material. It would therefore be very useful for the
operation of this site, as well as the design and operation of other similar sites, to use the results of the
effluent monitoring program in combination with known sediment characteristics to relate suspended
solids concentration to the state performance criterion of turbidity or transparency. This should be a
primary objective of the site monitoring program.
3.5 Groundwater Monitoring
Preliminary sub -surface investigations have documented relatively well -drained conditions for
much of Site MSA 640/640A. During a subsurface survey conducted in April, 1991, the water table
was located at a mean elevation of +1.81 ft NGVD, or approximately 4.26 ft below the undisturbed
23
mean site grade. Construction of the containment dikes, as described previously, will require the
excavation of the basin interior to a depth of approximately 3.2 ft below the mean grade of the site, or to
within approximately 0.74 ft of the water table.
Saltwater contamination of the shallow groundwater table outside of the containment dike is
unlikely for two reasons. First, a system of perimeter ditches surrounding the containment basin is
designed to limit the horizontal migration of saltwater. As discussed in Section 2.3.6, these ditches will
extend below the depth of excavation of the basin interior, and will intercept any seepage from the
containment basin, allowing it to drain back into the ICWW. Second, the MSA 6401640A containment
basin will impound brackish water pumped from the ICWW in connection with dredging operations for
relatively short periods of time (on the order of 4-6 weeks), no more than once every 10 to 12 years.
Thus, the risk of saltwater contamination of adjacent groundwater is considered minimal.
Nevertheless, because of the possibility of groundwater impacts, prior to commencement of
construction or disposal operations a groundwater monitoring program should be initiated. Such a
program will require that shallow test wells be sunk within the planned on-site buffer region which
separates the containment basin from adjacent properties. Baseline chloride concentrations will then be
determined for preconstruction conditions, and a regular monitoring program will be established to
document any deviations from these conditions. It should be noted that the developed properties adjacent
to the site receive water from a public utility. However, water for irrigation may be drawn from the
shallow aquifer. Continuing significant demands placed by adjacent properties on local groundwater
supplies could also result in salt water intrusion. Therefore, it is important that an ongoing well
monitoring program be kept in place throughout the design life of the site to distinguish any changes in
groundwater chloride concentrations which are attributable to site operations.
24
4.0 POST -DREDGING SITE MANAGEMENT
Following the completion of each dredging event the post -dredging phase of site operation begins.
This phase continues until the start of the next maintenance dredging event. During the post -dredging
phase, the dredged material deposited within the containment area is actively managed to increase the
rate at which its moisture content is reduced. In so doing, the material is made suitable for handling and
removal from the site. However, because of the permanent nature of the MSA 640/640A disposal site,
other management procedures between active dredging operations will also be required. These include a
comprehensive monitoring and data collection effort to guide the efficient use and environmental
compliance of the disposal area, the handling of stormwater runoff, the monitoring and maintenance of
site habitat, mosquito control measures, and the provision of permanent site security measures. These
are discussed in the following paragraphs.
4.1 Dewatering Operations
The sediment to be deposited in Site MSA 640/640A is expected to consist predominately of fine
sand, but may also contain a significant component of finer grained material, or silt. Based on the
experience of the Jacksonville Corps of Engineers, the material to be dredged may comprise up to 25 per
cent fine grained materials. Such material may prove difficult to dewater through natural evaporative
drying alone. In addition, the depth of the deposition may further retard drying because of limited
surface area. Therefore, supplementary dewatering techniques may be required to lower the moisture
content of the finer grained fraction of the deposited material, including surface water removal, shallow
trenching to promote continued drainage, and mechanical reworking of the dried deposition layer. Each
of these procedures and its specific application to the present situation are discussed below.
The decanting of all remaining surface water is necessary before significant evaporative drying of
the fine grained material can occur. Most of the ponded water is removed following the completion of
dredging operations by simply continuing to lower the weir crest. However, it is unlikely that all
ponded water can be drained off in this manner because of the topography of the surface of the
deposition layer. As previously discussed, differential settling of the various size fractions of the
sediment results in partial segregation of the dredged material within the containment basin. Coarser
sand and gravel -sized particles are deposited nearer the inlet, while finer particles settle nearer the weirs.
As the fine grained sediment dries, it will consolidate under the pressure of its own weight resulting in
25
the formation of a depression. To remove the ponded water which remains in this area, it will be
necessary to excavate a trench connecting the depression to the weirs. It may also be necessary to
excavate a sump adjacent to the weirs to receive the remaining ponded water. During this phase of
operations, the weir crest must be raised to prevent the premature release of the remaining ponded
water, which as a result of the excavation, will contain high suspended solids concentrations. Clarified
water can then be released over the weirs as soon as effluent turbidity standards are met.
In addition, a system of drainage trenches will be needed to continue lowering the moisture
content of the deposition layer. The area of coarser material near the inlet is expected to be relatively
free -draining; therefore, trenching can be limited to the area of fine-grained material nearer the weirs.
The thickness of the deposition layer (up to 6.0 ft) will require a series of trenching operations to
progressively lower the water content in successively deeper layers of the deposition. Prior to the
formation of crust on the surface of the drying material, an initial perimeter trench can be excavated by
dragline or clamshell operating from the crest of the containment dike. Alternatively, a Riverine Utility
Craft (RUC) developed for the U.S. Navy or a similar amphibious vehicle can be used for the initial
shallow trenching operation. More intensive trenching should wait until a significant crust (greater than
5-6 inches) has developed on the sediment surface, allowing the formation of desiccation cracks, and
retarding additional evaporative drying. A system of radial or parallel trenches should then be
constructed throughout the area of fine deposition. The depth of each trenching operation is dictated by
the resistance to slumping of the semi-liquid layer beneath the crust. As the water table within the
deposition layer is lowered by drainage and evaporation and the thickness of the crust increases, the
trenches must be progressively deepened. Alternatively, the dried surface material can be removed off-
site or simply transferred to a well -drained area within the containment basin. This would expose the
wetter underlayers and restore a relatively high rate of evaporative drying.
The dewatering process will continue until the crust extends over the entire depth of the
deposition layer. The time required to complete this phase of site operation will depend on the physical
characteristics of the sediment, as well as climatic conditions (e.g. rainfall, relative humidity, season,
etc.). During the entire dewatering phase of the site operation, the weirs must be operated to control the
release of residual water and impounded stormwater.
26
4.2 Grading the Deposition Material
If the inlet placement strategy discussed in Section 3.2 results in a deposit of fine material of
sufficient thickness (greater than 1-2 ft) to allow efficient removal by conventional equipment, this
should be done prior to grading. Removal of the fine material at this time offers several advantages.
The primary advantage is the segregation of that fraction of sediment which is least desirable for
recovery and re -use, thereby rendering the remaining coarser material more marketable. Removal of the
fine sediment also prevents the subsequent formation of a depression near the weirs as the finest -grained
material which concentrates in this area continues to consolidate under pressure from succeeding
deposits.
Grading of the deposition layer should begin as soon as possible following either the completion
of dewatering operations or the removal of the fine grained fraction, if appropriate. The grading should
consist primarily of distributing the mounded coarser sediment (sand, shell, gravel, etc.) over the
remainder of the containment area so as to re-establish the initial uniform 0.2 per cent downward slope
from inlet to weir.
As previously discussed (Section 2.1), the grading of the dewatered deposition layer is essential
for the control and release of stormwater runoff. A shallow, uniform slope toward the weirs will ensure
adequate drainage and eliminate the ponding of runoff in irregular depressions. It will also minimize
flow velocities and the risk of channelization and erosion. In compliance with regulatory policy, a sump
or retention area should be constructed adjacent to the weirs of adequate capacity (with the weir flash
boards in place) to retain the runoff from the first one inch of rainfall. For the MSA 640/640A
containment basin interior area of 3.57 acres (from the dike crest centerline inward), a retention pond
with a minimum capacity of approximately 12,950 ft3 will be required. This capacity can be provided
by a circular basin with a radius of 64 ft and an average depth of 1.0 ft. A site operator would then be
responsible for the gradual release of the ponded runoff at intervals to be determined by local weather
conditions. It may also be necessary to provide shallow trenches or swales from the center of the
retention basin to one or more weir sections so that the runoff may be quickly and completely released.
27
4.3 Material Rehandling/Reuse
As discussed in Section 1.0, Site MSA 640/640A is one of eight proposed disposal areas designed
to serve the long-term maintenance requirements of the Intracoastal Waterway within Palm Beach
County. Throughout this report, as well as the accompanying permit documentation, it has been
emphasized that although each site has been designed for a specific service life, the site is to be operated
as a permanent facility for the intermediate storage and re -handling of dredged maintenance material.
Due to the limited capacities of the upland sites in Palm Beach County (including MSA 640/640A), the
dewatered material must be removed on a regular basis for continued operations throughout the 50 year
design life of the program. Therefore, it is essential to develop a plan of action to deal with this
material. The ultimate use of this material is discussed in the following paragraphs.
Based on a comprehensive analysis of dredging records, the bulked disposal volume over the 50 -
year design service life of the eight Palm Beach County facilities is projected to be 5.5 million cubic
yards of predominantly fine to medium quartz sand. Although relatively minor by the standards of some
dredging operations, this volume still represents a significant quantity of potentially valuable construction
material. Even if the possible return on the sale of this material were disregarded, the savings on the
cost of permanent storage alone would justify a concentrated effort on the part of the State of Florida to
determine through a formal market analysis the potential demand for dewatered dredged material.
If such an analysis determines that material resale and/or reuse is practical, it must then be
demonstrated that the engineering properties of the dredged material satisfy the requirements of
commercial interests. It is anticipated that much of the material can be used 'as is', having been
partially segregated through differential settling. However, the feasibility of compartmentalized
segregation of material during disposal or mechanical separation following dewatering should be
explored if market conditions dictate. Portions of the material that are determined to be unsuitable for
fill or other construction purposes because of high organic silt or clay content might be used as capping
material for landfills, or as agricultural material.
If the market analysis determines that resale or reuse is not feasible, it will be necessary to locate
and develop a centralized permanent storage facility. The appropriate location for such a facility would
appear to be inland, where lower real estate values and development potential make permanent storage
Flo
more economically feasible. The optimal distance from the initial containment area to the permanent
storage site would represent a compromise between lower land costs and higher transportation expense.
4.4 Monitoring of Containment Area Performance
Several monitoring programs relevant to site management between successive disposal operations
have already been discussed. These include the monitoring of shallow aquifer groundwater for evidence
of elevated chloride concentrations, and the analysis of the stormwater runoff effluent released over the
weirs. These programs should continue throughout the service life of the site, although the sampling
interval between active disposal operations may be extended to coincide with regular site inspections
required to maintain security.
Additional site monitoring in the form of topographic surveys of the containment area deposition
surface is also recommended. These surveys consist of three basic types. The first is a post -dredging
survey which should be performed as soon as possible following the completion of material dewatering
operations and initial grading of the deposition surface. From this, a refined estimate of the quantity of
material deposited can be obtained. The second type of topographic survey would follow the completion
of material removal and related grading operations. Results from this survey would be used to compute
the quantity of material removed and the remaining site capacity. The third type of recommended
topographic survey is referred to here as a pre -dredging survey. During periods in which no material is
removed between dredging events this survey would be performed prior to the commencement of
disposal operations. Results obtained, in combination with information obtained from the previous post -
dredging survey, can be used to determine the amount of material consolidation which has occurred, and
to compute remaining site capacity.
In conjunction with the monitoring of material consolidation, a series of core borings taken after
the completion of de -watering would further define the progress of consolidation while providing a
means to determine the engineering properties of the dewatered material and its suitability for re -use.
Samples should be analyzed for grain size distribution, Atterberg limits, moisture and organic content,
and other factors which may affect the marketability of the material.
29
4.5 Continuing Monitoring Requirements
As seen in Figure 4-1, vegetation on Site MSA640/640A consists of Brazilian pepper, Australian
pine, and a disturbed area which has been planted in Saint Augustine grass and other landscape species.
Even though these exotic vegetation communities contain few species of environmental significance, their
presence is an essential element of the site layout. Portions of these communities will provide a buffer
around the site perimeter as a means of minimizing the impact of the presence of the containment basin.
Despite the environmental considerations which have gone into the design of Site MSA 640/640A, and
the attempt to limit construction and disposal operations to the area of the containment basin and
surrounding ditches, the possibility exists that the buffer areas may be impacted. Therefore, continuing
efforts should be undertaken to document and identify changes in species occurrence and habitat within
the buffer area. A comprehensive environmental survey of the site will be completed prior to any
construction to establish baseline habitat and vegetation conditions. Periodic re -surveys should continue
throughout the service life of the site. Degradation of habitat related to the interruption of natural
drainage patterns, groundwater impacts, or other possible consequences of site construction or operations
should be noted, corrective actions taken, and guidelines developed to minimize further adverse impact.
Similarly, any beneficial aspects of site management should be recognized and encouraged, and the
lessons learned should be applied to the future operation of this and other comparable disposal areas.
4.6 Mosquito Control
The basic approach of the mosquito control program for Site MSA 640/640A will be physical
control through the minimization of periods during which standing water exists inside of the containment
area. The phase of site operation which provides conditions most favorable for mosquito breeding
occurs during the dewatering of sediment when desiccation cracks form in the crust as the fine sediment
deposits shrink through evaporative drying. Trenching procedures (Section 4.1) will accelerate the
dewatering process by allowing much of the moisture within the cracks to drain to the weirs. However,
adverse climatological conditions could delay the dewatering phase long enough to result in successful
mosquito breeding within the desiccation cracks. This would require a short-term spray program
coordinated through the Palm Beach County Office of Environmental Services.
30
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4.7 Site Security
A key element in the proper management of Site MSA 640/640A is the provision of adequate site
security. Disposal areas have typically been subject to a variety of unauthorized activities including
illegal dumping, vandalism, hunting, and the destruction of dikes through the use of off-road vehicles.
The occurrence of such activities on Site MSA 640/640A will be controlled by the installation of security
fencing around the entire site perimeter. This will restrict the entry of unauthorized parties throughout
the design life of the site. Containment area access gates will remain locked at all times except during
disposal and maintenance operations.
The presence of an on-site operator during all phases of active disposal and de -watering
operations should further discourage unauthorized entry to the site and the occurrence of non -sanctioned
activities. Between disposal operations the site operator will be responsible for carrying out regularly
scheduled inspections. The primary purpose of these inspections will be to perform routine operational
functions, and to ensure that the security of the facility is maintained. Breaches in site security will be
identified and appropriate actions will be taken as quickly as possible to restore the site to a fully
operational standby condition. Other responsibilities of the operator during these visits will include weir
operation and stormwater release, monitoring of stormwater effluent quality and groundwater monitoring
wells, as well as the performance of routine inspections of dike integrity and buffer area conditions.
32
Bromwell and Carrier, Inc., "Long -Range Dredged Material Management Plan, Atlantic Intracoastal
Waterway, Palm Beach County, Florida", December, 1989, Lakeland, Florida.
Gallagher, B.I., and Company, "Investigation of Containment Area Design to Maximize Hydraulic
Efficiency", Technical Report D-78-12, May 1978, U.S. Army Corps of Engineers Waterways
Experiment Station, CE, Vicksburg, Mississippi.
Haliburton, T.A., "Guidelines for Dewatering/Densifying Confined Dredged Material", Technical
Report DS -78-11, September 1978, U.S. Army Corps of Engineers Waterways Experiment
Station, CE, Vicksburg, Mississippi.
Palermo, M.R., R.L. Montgomery, and M.E. Poindexter, "Guidelines for Designing, Operating, and
Managing Dredged Material Disposal Areas", Technical Report DS -78-10, December, 1978,
U.S. Army Corps of Engineers Waterways Experiment Station, CE, Vicksburg, Mississippi.
Shields, F.D., Jr. E.L. Thackston, and P.R. Schroeder, "Design and Management of Dredged Material
Containment Areas to Improve Hydraulic Performance", Technical Report D-87-2, June 1987,
U.S. Army Corps of Engineers Waterways Experiment Station, CE, Vicksburg, Mississippi.
Taylor, R.B., "Letter Report to Art Wilde, Executive Director, Florida Inland Navigation District,
Dated July 12, 1990", Taylor Engineering, Inc., Jacksonville, Florida.
Walski, T.M. and P.R. Schroeder, "Weir Design to Maintain Effluent Quality from Dredged Material
Containment Areas", Technical Report D-78-18, May 1978, U.S. Army Corps of Engineers
Waterways Experiment Station, CE, Vicksburg, Mississippi.
33