1
United States
Environmental Protection
Agency
EPA, Region II
Office of Policy and Management
Environmental Impacts Branch
New York. N Y T0278
SEPTEMBER 1986
Water
¦SEPA Draft
Environmental Impact
Statement for the
Designation of Ocean
Dredged Material Disposal
Sites for Arecibo,
Mayaguez, Ponce, and
Yabucoa, Puerto Rico
67°00'
66°30*
66°00'
65°30'
ATLANTIC OCEAN
18°30'
18°15'
CARIBBEAN SEA
17°45
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION li
26 FEDERAL PLAZA
NEW YORK. NEW YORK 10278
SEP 3 1986
To All Interested Government Agencies and Public Groups:
This is to inform you that the Draft Environmental Impact Statement (EIS) for
the Designation of Ocean Dredged Material Disposal Sites for Arecibn. MavamiP?.
Ponce, and Yabucoa, Puerto Rico will be available for onhl"r
following locations:
U.S. Environmental Protection Agency
Environmental Impacts Branch
26 Federal Plaza, Room 702
New York, New York
U.S. Environmental Protection Agency
Caribbean Field Office
1413 Avenida Fernandez Juncos - Stop 20
Santurce, Puerto Rico
U.S. Environmental Protection Agency
Public Information Reference Unit
Rocm 2904 (Rear)
401 M Street, S.W.
Washington, D.C.
U.S. Army Corps of Engineers
Jacksonville District Office
400 W. Bay Street
Jacksonville, Florida
U.S. Army Corps of Engineers
San Juan Area Office
400 Avenida Fernandez Juncos
San Juan, Puerto Rico
This draft environmental impact statement (DEIS) was prepared by the U.S.
Environmental Protection Agency (EPA) - Region II, with the assistance of JRB
Associates, Inc., an environmental consulting firm. This document has been
prepared in accordance with the regulations for implementation of the National
Environmental Policy Act (NEPA), and in accordance with EPA's procedures for
voluntary preparation of EISs on significant regulatory actions (39 FR 37119).
Puerto Rico Department of
Natural Resources
Oficina 204
Centro Gubernanental
Avenida Rotarios
Arecibo, Puerto Pico
Puerto Rico Department of
Natural Resources
Oficina A
Centro Corrercial
2 Alturas de Mayaguez Carr.
Mayaguez, Puerto Rico
Puerto Rico Department of
Natural Resources
5 Calle Celenia
Humacao, Puerto Rico
Puerto Rico Department of
Natural Resources
Hospital Sub-Regional
Ponce, Puerto Rico
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2
An EIS is a decision-making document. This DEIS was prepared for the purpose
of evaluating the environmental impacts associated with the designation of sites
for ocean disposal of dredged material from the harbors of Arecibo, Mayaguez,
Ponce, and Yabucoa, Puerto Rico, and utilizes this evaluation in proposing
particular sites for designation.
This document is in two volumes. Volume I includes the following: an executive
summary plus chapters on the purpose of and need for the action, alternatives,
selection of alternate sites and proposed actions, characteristics of the
affected environments, and environmental consequences for each disposal site.
Volume II includes eight appendices that contain detailed analyses used to
evaluate the effects of the proposed action.
Corrments concerning the content of this DEIS may be submitted to the EPA for
consideration. All ccmnents nust be received within 60 days after the date of
publication of the Notice of Availability for this DEIS in the Federal Register,
which is expected to be Qct.nhpr 10. 1986 Please address all comments to
Ms. Barbara Pastalove, Chief, Environmental Irrpacts Branch, Roan 702, U.S.
Environmental Protection Agency, 26 Federal Plaza, New York, NY 10278.
If you require additional information regarding this DEIS, please contact
Mr. Robert Witte, Project Monitor, at (212) 264-5396.
Sincerelv.
Christopher J. Daggett
Regional Administrator - Region II
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ABSTRACT
-------
ABSTRACT
The proposed action addressed in this Environmental Impact Statement
(EIS) is the designation of ocean dredged material disposal sites for Puerto
Rico. The purpose of the action is to provide environmentally acceptable
alternatives for disposal of dredged material from the four harbors of
Arecibo, Mayaguez, Ponce, and Yabucoa.
Locations of presently used interim sites are:
• Arecibo - 1.5 nautical miles (2.7 km) north of the harbor
• Mayaguez - 5 nautical miles (9.3 km) northwest of the harbor
• Ponce - 4 nautical miles (7.4 km) south of the harbor
• Yabucoa -4.5 nautical miles (8.3 km) east of the harbor.
Two alternate sites for Arecibo and three alternate sites each for Mayaguez,
Ponce, and Yabucoa were identified using a site selection methodology
developed by the Environmental Protection Agency and the U.S. Army Corps of
Engineers.
The analysis conducted for the EIS indicated that at Arecibo the interim
site, located approximately 1.5 nautical miles north of the harbor, should be
designated as the ocean site for dredged material disposal. At Mayaguez,
alternate site 1, approximately 8 nautical miles west of the harbor, should be
designated as the ocean site for dredged material disposal. At Ponce, alter-
nate site 1, about 5 nautical miles south of the harbor, should be designated
as the disposal site. At Yabucoa, alternate site 2, approximately 6 nautical
miles east of the harbor, should be designated as the disposal site.
Alternate land-based disposal methods considered in the analysis included
placement of dredged material as hydraulic fill, use of dredged material to
create wetlands, and use as cover material in landfills or barren areas. For
Arecibo, land-based alternatives are not as environmentally acceptable as the
ocean sites for dredged material disposal. For Mayaguez, Ponce, and Yabucoa,
suitable areas limited in size may exist, but a lack of site-specific field
data prevents an assured determination of the environmental impacts that would
result from disposal at those sites.
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Draft
Environmental Impact Statement
for the Designation of Dredged Material
Disposal Sites for the Harbors of
Arecibo, Mayaguez, Ponce, and
Yabucoa, Puerto Rico
U.S. Environmental Protection Agency
Region II
Environmental Impacts Branch (2PM-EI)
26 Federal Plaza
New York, NY 10278
SEPTEMBER 1986
-------
Draft Environmental Inpact Statement
for the Designation of Ocean Dredged Material Disposal
Sites for Arecibo, Mayaguez, Ponce, and
Yabucoa, Puerto Rico
June 1986
Prepared by
Environmental Protection Agency - Region II
Abstract: In accordance with the National Environmental Policy Act (NE h)^
and the regulations of the U.S. Environmental Protection Agency (EPA), we have
prepared a draft environmental impact statement (DEIS) for the designation o
four ocean dredged material disposal sites for Puerto Rico. The purpose of the
proposed action is to provide environmentally acceptable alternatives for
disposal of dredged material from the harbors of Arecibo, Mayaguez, once, a
The four interim ocean disposal sites (one for each harbor) currently in use
were analyzed. In addition, two alternate sites for Arecibo an t ree a er
nate sites each for Mayaguez, Ponce, and Yabucoa, as well as other alternatives
(including land-based disposal methods), were identified and analyzed. The
analyses conducted for the DEIS indicated that for Arecibo, the interim site,
located approximately 1.5 nautical miles north of the harbor, should be desig-
nated as the ocean site for dredged material disposal. For Mayaguez,^an^alter-
Yabucoa, Puerto Rico.
as the disposal site. For Yabucoa, an alternate site, approximately 6 nautical
miles east of the harbor, should be designated as the isposa si e.
• ^ A _ C L n 1_ 1a a iW 1 « ^ ^ 4" 1 /N
if
"t
!.**-•** XV^J. rw f I V N— TT rk • V •
!.**-•** XV^J. rw f I V N— TT 1% • v •
VJitte, Project Monitor, at (212) 264-5396.
Regional Administrator
Date
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EXECUTIVE SUMMARY
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EXECUTIVE SUMMARY
This draft environmental impact statement (EIS) evaluates the environ-
mental consequences of designating an ocean dredged material disposal site
(DMDS) for each of the harbors of Arecibo, Mayaguez, Ponce, and Yabucoa,
Puerto Rico. The draft EIS identifies alternate ocean disposal sites for each
harbor, characterizes the affected environments and types of materials to be
released at the sites, and analyzes potential consequences of the proposed
action.
PURPOSE AND NEED FOR THE ACTION
The proposed actions discussed in this draft EIS are the final designa-
tions of environmentally acceptable ocean disposal sites for materials dredged
from the harbors and surrounding areas of Arecibo Harbor, the Port of Ponce,
the Port of Mayaguez, and Yabucoa Harbor (all referred to subsequently as
"harbors"). The purpose of the proposed actions is to designate final dredged,
material disposal sites in accordance with the requirements of the Marine
Protection, Research and Sanctuaries Act of 1972 (MPRSA) and the U.S. Envir-
onmental Protection Agency's (EPA's) implementation of the Ocean Dumping
Regulations (40 CFR 220-229).
The harbors of Arecibo, Mayaguez, Ponce, and Yabucoa are essential to
the continued commercial and industrial growth of Puerto Rico. Ocean-going
ships require channels, berths and turning basins that are, at a minimum, 10
meters deep. Each harbor is subject to gradual shoaling and filling in as a
result of sediment inputs from rivers and storm waves. Periodic maintenance
dredging is essential for the continued use of these harbors.
Since 1977, the U.S. Army Corps of Engineers (COE) has disposed of
materials from dredging operations in Puerto Rico at dredged material disposal
sites (DMDSs) designated by EPA on an interim basis. In 1980, the National
Wildlife Federation filed suit against the EPA and COE in an attempt to per-
S-l
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suade them to designate ocean dredged material disposal sites. Although thes
four Puerto Rico interim disposal sites are not included in the Consent Order
resulting from that suit, EPA is responding to the Corps of Engineers' need t
have designated ocean dredged material disposal sites and has initiated the
necessary studies to select, evaluate, and designate the most suitable sites
for the ocean disposal of dredged materials. This draft E1S was prepared to
provide information needed to assess the impacts associated with the final
designation of a dredged material disposal site (DMDS) for each harbor.
ALTERNATIVES INCLUDING THE PROPOSED ACTION
The proposed action is for the final designation of ocean dredged
material disposal sites for Arecibo, Mayaguez, Ponce, and Yabucoa, Puerto
Rico. The alternatives for each area include the following: no-action
(continued use of the interim site), non-ocean disposal, designation of the
interim site, and designation of one of the alternate sites.
Selection of the no-action alternative would result in EPA refraining
from designating ocean disposal sites. This is unacceptable, since continued
use of some of the interim sites would result in adverse environmental impacti
to reef and beach areas.
The non-ocean disposal alternatives evaluated include land disposal,
recycling and re-use options. The dredged material from the four harbors i6
primarily fine-grained material (silt and clay). This limits the land-based
disposal alternatives to the following options:
• Placement as hydraulic fill
• Formation of wetland habitats
• Use as cover material in landfills or barren areas.
Use of these land-based disposal alternatives would be hampered by the
limited number and size of potential disposal sites near the harbors and by
the possibility that sites with suitable location, topography, and geohydro-
logic characteristics cannot be acquired.
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At Arecibo, there are significant disadvantages associated with all of
the land-based alternative disposal options. Hydraulic fill locations are
likely to be limited in size and very expensive. Wetland production would be
hindered by climatic conditions (high wave energies) and lack of suitable
sites. Application of dredged material on land as a cover material could
degrade ground water quality in the area, particularly at sites far from the
coast. The only option that may be technically, environmentally, and economi-
cally feasible is use of one of the barren areas, if site specific studies
verify the presence of abandoned sand pits at the site.
The use of land-based disposal alternatives near Mayaguez may be tech-
nically feasible. No potential sites for hydraulic filling were identified;
however, one potential marsh production site, one or two landfill sites, and
one barren area site were identified. Prior to the use of any of these sites
for the disposal of dredged materials, an extensive site-specific field study
would be required.
The use of land-based disposal alternatives near Ponce may be technically
feasible. One potential diked containment area for placement of hydraulic
fill and one potential wetland formation area were identified. No landfills
were found suitable, but four small sand mining pits could be suitable if
found to be permanently unused because of sand depletion. Prior to the use of
any of these sites as dredged material disposal sites, an extensive site-
specific field study would be required.
The use of land-based dredged material disposal alternatives at Yabucoa
may be technically feasible. Sites suitable for hydraulic fill may be avail-
able, although no specific sites for diked containment areas were identified.
There is sufficient land of suitable topography for diked containment areas
near the coast in the Yabucoa Valley, however use of this land might be in
competition with its use as farmland. No sites suitable for wetland forma-
tion, landfill cover material application, or barren area cover material
application were identified near Yabucoa.
S-3
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From this analysis, it would appear that non-ocean alternatives would be
feasible only on a short-term basis, due to limited capacity and potential
conflicts with other uses for any possible sites.
Alternate ocean dredged material disposal sites to be evaluated by the
EIS were selected using a screening methodology developed by EPA and the COE.
A brief description of the phases of EPA/COE's recommended site-designation
process follows:
• Phase 1: Establish Zones of Siting Feasibility (ZSF's)
- A preliminary screening of environmental factors, based on
evaluation factors specified in MPRSA Section 102a and the
specified in the Ocean Dumping Regulations (ODR, Part 228)
eliminate areas of known conflict with protected resources
existing uses of the ocean
• Phase II: Select Alternate Sites
Evaluate interim dredged material disposal sites, and identify
other possible ocean disposal sites believed to be in accordance
with the ocean dumping criteria
• Phase III: Evaluate Interim and Alternate Sites
Evaluate the suitability of each of the sites and select, based on
ODR criteria, a site for designation as the DMDS for continuing
use.
The locations of the interim sites and the alternate sites selected
according to the EPA/COE methodology are indicated below:
• Arecibo
Interim Site
LAT
18 "30'30"N
(Figure S-l)
LONG
66 "43116"W
Alternate Site
#1
LAT
LONG
18 "31134"N
66°44'24"W
Alternate Site
n
LAT
LONG
18°31'48"N
66°46'00"W
• Mayaguez
Interim Site
LAT
18" 15'00"N
(Figure S-2)
LONG
67 °14'00"W
Alternate Site
#i
LAT
LONG
18"15,00"N
670 15 '42"W
the nine
criteria
to
and
S-4
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66°50'
66°A0'
66° 30*
-------
67° 30'
67°20'
67°10'
ZE
18
25'
18
20'
18
15'
18
10'
18
05'
18
00'
\
am gz)
m
/ *
/ *
100 fn'
Nautical Miles
(TTTTT1
18l
13
20'
Id"
15'
MAYAGUEZ
18
10'
13'
05'
;3°
JO'
67°30'
67°20'
FIGURE S-2. INTERIM AND ALTERNATE SITES FOR MAYAGUEZ
S-6
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• Ponce
(Figure S-3)
• Yabucoa
(Figure S-4)
Alternate
Site
#2
LAT
18oi5,06"N
LONG
67 "16'
148"W
Alternate
Site
#3
LAT
18°131
1 54"N
LONG
67 °16'
124"W
Interim Site
LAT
17"551
00"N
LONG
66°381
1 54"W
Alternate
Site
#1
LAT
17 ° 531
20"N
LONG
66°371
52"W
Alternate
Site
#2
LAT
17 ° 52'
00"N
LONG
66 °38'
54"W
Alternate
Site
#3
LAT
17 ° 52104"N
LONG
66037'42"W
Interim Site
LAT
18°02 1
06"N
LONG
65°45 '
00"W
A1ternate
Site
#1
LAT
18°01'
18"N
LONG
65°44'48"W
Alternate
Site
#2
LAT
18°031
12"N
LONG
65°42'
18"W
Alternate
Site
#3
LAT
IS'OS'SO"^
LONG
65°39'
16"W
ENVIRONMENTAL CONSEQUENCES
Continuing use of the interim dredged material disposal site for Mayaguez
or Yabucoa Harbors is likely to result in deposition of sediments at levels
harmful to corals in reef areas adjacent to the sites. It is not expected
that there will be any adverse effects on coral reefs from the use of any of
the alternate sites for Mayaguez, alternate sites 2 or 3 for Yabucoa, or the
interim or alternate sites for Arecibo or Ponce.
Copepods, fish eggs, and perhaps bivalve eggs can be seriously affected
by suspended sediment concentrations such as those immediately resulting from
the disposal of dredged materials. However, because of the transient nature
of suspended sediment plumes in the deep-water, open-ocean environments of all
considered sites, such planktonic organisms would not be exposed to the sedi-
ments for time periods long enough to have significant effects.
S-7
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66°00'
65°50
65O40'
-------
There should be no measurable increases in sediment concentrations at any
beaches or shorelines because of dredged material disposal at any of the
interim or alternate sites for Arecibo or Mayaguez. Use of alternate site 2
or 3 at Ponce or alternate site 1 at Yabucoa would cause a detectable increase
in ambient sedimentation levels at the shoreline.
There should be no effects on mineral resources, natural reserves, com-
monwealth forests, mangrove nursery areas, critical wildlife areas, or any
endangered species' habitats from disposal at the interm or alternate sites
for any of the four harbors. Therefore, no unreasonable degradation of the
marine environment is expected to occur as a result of the proposed action.
CONCLUSIONS
There is a confirmed need to dispose of large quantities of dredged
material from the ports and harbors of Puerto Rico. Land-based disposal
methods are not considered viable alternatives to ocean dredged material dis-
posal except on a short-term basis. Thus, the proposed action is designation
of dredged material disposal sites (DMDS) for continued use. For one harbor,
the proposed DMDS is the interim site. For the other three harbors, an alter-
nate site is proposed.
Of the disposal sites considered for Arecibo, the interim site is the
proposed site, 1.5 nautical miles (nmi) north of the harbor.
The proposed site for Mayaguez is alternate site 1. This site is 7 nmi
west of the harbor. The interim site was eliminated from consideration
because it is in relatively shallow water close to shore, where released
dredged materials are likely to be transported into a coral reef area.
The proposed site for Ponce is alternate site 1, which is located 5.5
nmi south of the harbor. The interim site was eliminated from consideration
because plumes of suspended sediments from the site are expected to reach the
shorelines, beaches, and coral reefs near a commonwealth forest natural
reserve area.
S-10
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The proposed site for Yabucoa is Alternate Site No.2, 6 nmi east of the
harbor. The interim site was not selected because it includes a very shallow
area inhabited by corals, and because sediment plumes from the interim site
could be carried close to shorelines and into an important nearshore
commercial fishing area.
S-ll
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TABLE OF CONTENTS
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TABLE OF CONTENTS
Page
EXECUTIVE SUMMARY S- 1
1. PURPOSE OF AND NEED FOR ACTION 1- 1
1.1 PURPOSE OF ACTION 1-1
1.2 ARMY CORPS OF ENGINEERS NEED FOR ACTION 1- 1
1.3 CORPS OF ENGINEERS LOCAL NEED FOR ACTION 1- 7
1.3.1 Need for Dredging, Arecibo 1- 7
1.3.2 Need for Dredging, Mayaguez 1-8
1.3.3 Need for Dredging, Ponce 1- 8
1.3.4 Need for Dredging, Yabucoa 1- 9
1.4 ENVIRONMENTAL PROTECTION AGENCY'S NEED FOR ACTION 1- 9
1.5 INTERNATIONAL CONSIDERATIONS 1-10
2. ALTERNATIVES INCLUDING THE PROPOSED ACTION 2- 1
2.1 NO-ACTION ALTERNATIVE 2- 1
2.2 NON-OCEAN DISPOSAL ALTERNATIVE 2- 1
2.2.1 Introduction 2- 2
2.2.2 Justification for Evaluation of Land Based
Disposal 2- 2
2.2.3 Available Land-Based Disposal Methods 2- 2
2.2.3.1 Factors Affecting Selection of Land-
Based Disposal Alternatives 2- 3
2.2.3.2 Land-Based Disposal Options for Fine-
Grained Sediments 2- 6
2.2.4 Land-Based Options for Each Harbor 2- 9
2.2.4.1 Land-Based Disposal Options for Arecibo... 2- 9
2.2.4.2 Land-Based Disposal Options for Mayaguez.. 2- 9
2.2.4.3 Land-Based Disposal Options for Ponce 2-12
2.2.4.4 Land-Based Disposal Options for Yabucoa... 2-12
2.2.5 Conclusions Concerning Options for Land Disposal... 2-15
2.3 SELECTION OF ALTERNATE OCEAN DISPOSAL SITES 2-15
2.3.1 The EPA/COE Protocol for Ocean Dredged Material
Disposal Site (DMDS) Designation 2-15
2.3.1.1 Criteria for Evaluating Interim Sites and
Selecting and Evaluating Alternate Sites
from the Ocean Dumping Regulations 2-16
i
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TABLE OF CONTENTS
(continued)
2.3.1.2 Phase I: Establish Zones of Siting
Feasibility 2-17
2.3.1.3 Phase II-Select Alternate Ocean
Disposal Sites 2-18
2.4 PROPOSED ACTION FOR ARECIBO 2-24
2.4.1 Characteristics of the Dredged Material - Arecibo.. 2-24
2.4.1.1 Grain Size of Material 2-24
2.4.1.2 Existence of Contaminants as Indicated
by Elutriate Tests 2-24
2.4.1.3 Existence of Contaminants as Indicated
by Bioassay 2-26
2.4.2 Detailed Consideration of the Alternate Sites 2-26
2.4.3 Summary: Proposed Site for Arecibo 2-32
2.5 PROPOSED ACTION FOR MAYAGUEZ 2-33
2.5.1 Characteristics of the Dredged
Material - Mayaguez 2-33
2.5.1.1 Grain Size of the Material 2-33
2.5.1.2 Existence of Contaminants as Indicated
by Elutriate Tests 2-35
2.5.1.3 Existence of Contaminants as Indicated
by Bioassay 2-35
2.5.2 Detailed Consideration of the Alternate Sites 2-35
2.5.3 Summary: Proposed Site for Mayaguez 2-41
2.6 PROPOSED ACTION FOR PONCE 2-42
2.6.1 Characteristics of the Dredged Material - Ponce.... 2-42
2.6.1.1 Grain Size of the Material 2-42
2.6.1.2 Existence of Contaminants as Indicated
by Elutriate Tests 2-44
2.6.1.3 Existence of Contaminants as Indicated
by Bioassay 2-44
2.6.2 Detailed Consideration of the Alternate
Sites 2-46
2.6.3 Summary: Proposed Site for Ponce 2-52
ii
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TABLE OF CONTENTS
(continued)
2.7 PROPOSED ACTION FOR YABUCOA. . . 2-52
2.7.1 Characteristics of the Dredged Material - Yabucoa.. 2-52
2.7.1.1 Grain Size of the Material 2-52
2.7.1.2 Existence of Contaminants as Indicated
by Elutriate Tests 2-54
2.7.1.3 Existence of Contaminants as Indicated
by Bioassay 2-54
2.7.2 Detailed Consideration of the Alternate Sites 2-56
2.7.3 Summary: Proposed Site for Yabucoa 2-62
3. CHARACTERISTICS OF AFFECTED ENVIRONMENTS 3- 1
3.0.1 Soft-Bottom Benthic Communities 3- 1
3.0.2 Ecological Characteristics of Puerto Rican Corals
and Associated Fish Communities 3- 3
3.0.3 Mangroves: Special Breeding and Nursery Areas 3- 5
3.0.4 Fisheries 3- 6
3.1 CHARACTERIZATION OF THE AFFECTED ENVIRONMENT FOR ARECIBO.. 3- 7
3.1.1 Oceanographic and Climatological Characteristics... 3- 7
3.1.1.1 Bathymetry 3- 7
3.1.1.2 Climatology 3- 7
3.1.1.3 Hydrography 3- 9
3.1.1.4 Circulation 3- 9
3.1.2 Geologic and Geochemical Characteristics 3-14
3.1.2.1 Surficial Geology 3-14
3.1.2.2 Sea Floor Characteristics and Sediment
Textures 3-17
3.1.2.3 Sediment Mineralogy 3-18
3.1.3 Water Quality... 3-19
3.1.3.1 Turbidity............ 3-19
3.1.3.2 Dissolved Oxygen 3-19
3.1.3.3 Nutrients 3-22
3.1.4 Biota 3-25
3.1.4.1 Benthic Invertebrates 3-25
3.1.4.2 Coral Reefs 3-25
3.1.4.3 Mangrove, Breeding and Nursery Areas. 3-27
3.1.4.4 Preserves and Reserves 3-27
3.1.4.5 Threatened and Endangered Species 3-27
iii
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TABLE OF CONTENTS
(continued)
3.1.5 Recreational Areas 3~3o
3.1.6 Shipping Lanes 3-3q
3.1.7 Mineral Resources 3-31
3.1.8 Shipwrecks or Other Features of Historical or
Cultural Importance 3-31
3.1.9 Fisheries 3-31
3.2 CHARACTERIZATION OF THE AFFECTED ENVIRONMENT
FOR MAYAGUEZ 3~32
3.2.1 Oceanographic and Climatological Characteristics... 3-32
3.2.1.1 Bathymetry 3-32
3.2.1.2 Climatology 3-32
3.2.1.3 Hydrography 3-34
3.2.1.4 Circulation 3-38
3.2.2 Geologic and Geochemical Characteristics 3-38
3.2.2.1 Surficial Geology 3-38
3.2.2.2 Sea Floor Characteristics and Sediment
Textures 3-41
3.2.2.3 Sediment Minerology 3-43
3.2.3 Water Quality 3-44
3.2.3.1 Turbidity 3-44
3.2.3.2 Dissolved Oxygen 3-44
3.2.3.3 Nutrients 3-46
3.2.4 Biota 3-49
3.2.4.1 Benthic Invertebrates 3-49
3.2.4.2 Coral Reefs 3-50
3.2.4.3 Mangrove, Breeding and Nursery Areas 3-50
3.2.4.4 Preserves and Reserves 3-53
3.2.4.5 Threatened and Endangered Species 3-53
3.2.5 Recreational Areas 3-53
3.2.6 Shipping Lanes 3-55
3.2.7 Mineral Resources 3-55
3.2.8 Shipwrecks or Other Features of Historical or
Cultural Importance 3-55
3.2.9 Fisheries 3-55
iv
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TABLE OF CONTENTS
(continued)
3.3 CHARACTERIZATION OF THE AFFECTED ENVIRONMENT FOR PONCE 3-56
3.3.1 Oceanographic and Climatological Characteristics... 3-56
3.3.1.1 Bathymetry 3-56
3.3.1.2 Climatology 3-57
3.3.1.3 Hydrography 3-56
3.3.1.4 Circulation 3-61
3.3.2 Geologic and Geochemical Characteristics 3-64
3.3.2.1 Surficial Geology 3-65
3.3.2.2 Sea Floor Characteristics and Sediment
Textures 3-65
3.3.2.3 Sediment Minerology 3-67
3.3.3 Water Quality 3-68
3.3.3.1 Turbidity 3-68
3.3.3.2 Dissolved Oxygen 3-68
3.3.3.3 Nutrients 3-72
3.3.4 Biota 3-72
3.3.4.1 Benthic Invertebrates 3-75
3.3.4.2 Coral Reefs 3-77
3.3.4.3 Mangrove, Breeding and Nursery Areas 3-77
3.3.4.4 Preserves and Reserves 3-79
3.3.4.5 Threatened and Endangered Species 3-79
3.3.5 Recreational Areas 3-79
3.3.6 Shipping Lanes 3-81
3.3.7 Mineral Resources 3-81
3.3.8 Shipwrecks or Other Features of Historical or
Cultural Importance 3-81
3.3.9 Fisheries 3-81
3.4 CHARACTERIZATION OF THE AFFECTED ENVIRONMENT FOR YABUCOA.. 3-82
3.4.1 Oceanographic and Climatological Characteristics... 3-82
3.4.1.1 Bathymetry 3-82
3.4.1.2 Climatology 3-82
3.4.1.3 Hydrography 3-84
3.4.1.4 Circulation 3-88
3.4.2 Geologic and Geochemical Characteristics 3-90
v
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TABLE OF CONTENTS
(coat inued)
3.4.2.1 Surficial Geology 3-92
3.4.2.2 Sea Floor Characteristics and Sediment
Textures 3-92
3.4.2.3 Sediment Minerology 3-94
3.4.3 Water Quality 3-95
3.4.3.1 Turbidity 3-95
3.4.3.2 Dissolved Oxygen 3-97
3.4.3.3 Nutrients 3-98
3.4.4 Biota 3-102
3.4.4.1 Benthic Invertebrates 3-102
3.4.4.2 Coral Reefs 3-102
3.4.4.3 Mangrove Breeding and Nursery Areas 3-104
3.4.4.4 Preserves and Reserves 3-104
3.4.4.5 Threatened and Endangered Species 3-107
3.4.5 Recreational Areas..... 3-107
3.4.6 Shipping Lanes 3-108
3.4.7 Mineral Resources 3-108
3.4.8 Shipwrecks or Other Features of Historical or
Cultural Importance 3-108
3.4.9 Fisheries 3-108
3.5 IDENTIFICATION OF ORGANISMS 3-109
4.0 ENVIRONMENTAL CONSEQUENCES 4-1
4.1 METHODS FOR EVALUATING EXPECTED TRANSPORT OF SEDIMENT
PLUMES FROM DISPOSAL SITES 4-1
4.2 SENSITIVITIES OF MARINE ORGANISM OTHER THAN CORALS
TO SUSPENDED SEDIMENTS 4-2
4.3 SENSITIVITY OF CORAL COMMUNITIES TO SEDIMENTS IN THE
ENVIRONMENT 4-5
4.3.1 Types of Sediment Impact on Reef Communities 4-5
4.3.2 Effects of Turbidity and Impact Threshold Levels... 4-6
4.3.3 Effects of Sedimentation and Impact Threshold
Levels 4-6
4.3.4 Effects of Burial 4-7
4.3.5 Conclusion: Coral Sensitivity Thresholds to
Sedimentation 4-8
4.4 ENVIRONMENTAL CONSEQUENCES OF DREDGED MATERIAL DISPOSAL
FOR ARECIBO 4-8
vi
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TABLE OF CONTENTS
(continued)
4.4.1 Impacts on Beaches and Shorelines 4-8
4.4.2 Impacts on Coral Reefs 4-10
4.4.3 Impacts in Preserve or Reserve Areas or
Mangrove Nursery Areas 4-10
4.4.4 Effects on Threatened and Endangered Species 4-10
4.4.5 Shipping Lanes 4-11
4.4.6 Mineral Resources 4-11
4.5 ENVIRONMENTAL CONSEQUENCES OF DREDGED MATERIAL DISPOSAL
FOR MAYAGUEZ 4-11
4.5.1 Impacts on Beaches and Shorelines 4-11
4.5.2 Impacts on Coral Reefs 4-11
4.5.3 Impacts in Preserve or Reserve Areas or Mangrove
Nursery Areas 4-16
4.5.4 Effects on Threatened and Endangered Species 4-16
4.5.5 Shipping Lanes 4-16
4.5.6 Mineral Resources 4-16
4.6 ENVIRONMENTAL CONSEQUENCES OF DREDGED MATERIAL
DISPOSAL FOR PONCE 4-17
4.6.1 Impacts on Beaches and Shorelines 4-17
4.6.2 Impacts on Coral Reefs 4-17
4.6.3 Impacts in Preserve or Reserve Areas, or
Mangrove Nursery Areas 4-20
4.6.4 Effects on Threatened and Endangered Species 4-20
4.6.5 Shipping Lanes 4-20
4.6.6 Mineral Resources 4-21
4.7 ENVIRONMENTAL CONSEQUENCES OF DREDGED MATERIAL DISPOSAL
FOR YABUCOA 4-21
4.7.1 Impacts on Beaches and Shorelines 4-21
4.7.2 Impacts on Coral Reefs 4-21
4.7.3 Impacts in Preserve or Reserve Areas, or
Mangrove Nursery Areas 4-23
4.7.4 Effects on Threatened and Endangered Species 4-23
4.7.5 Shipping Lanes 4-23
4.7.6 Mineral Resources 4-23
4.8 SUMMARY: CONSEQUENCES OF PROPOSED
SITE DESIGNATIONS FOR ALL HARBORS 4-25
4.8.1 Irreversible and Irretrievable
Commitment of Resources for All Harbors 4-25
4.8.2 Steps to Minimize Adverse
Effects to the Environment for All Harbors 4-25
vii
-------
TABLE OF CONTENTS
(continued)
A.8.3 Relationship Between Short-Term Use of the
Environment and Long-Term Use of the
Environment for All Harbors 4-26
5. CONTRIBUTORS TO THE EIS 5-1
6. COORDINATION WITH OTHER GOVERNMENT AGENCIES, NON-GOVERNMENT
ORGANIZATIONS, AND PERSONS 6-1
6.1 GLOSSARY 6-1
6.2 LIST OF ABBREVIATIONS AND ACRONYMS 6-6
6.3 UNIT CONVERSION TABLE 6-8
7. REFERENCES 7-1
viii
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APPENDICES (VOLUME TWO)
APPENDIX A - GLOSSARY, LIST OF ABBREVIATIONS, UNIT CONVERSION TABLE...A-l
APPENDIX B - DREDGING HISTORY OF ARECIBO, MAYAGUEZ, PONCE, AND
YABUCOA, PUERTO RICO B-l
APPENDIX C - ANALYSIS OF LAND-BASED DISPOSAL ALTERNATIVES C-l
APPENDIX D - ASSESSMENT OF CHEMICAL AND PHYSICAL EFFECTS ON BIOTA... D-l
APPENDIX E - THE EFFECTS OF DREDGED MATERIAL DISPOSAL ON CORAL
COMMUNITIES E-l
APPENDIX F - OCEANOGRAPHIC AND CLIMATOLOGIC CHARACTERISTICS
PONCE AND YABUCOA F-l
APPENDIX G - DREDGED MATERIAL TRANSPORT AND FATE MODEL G"1
APPENDIX H - STORM-INDUCED SEDIMENT TRANSPORT MODEL H-l
ix
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LIST OF FIGURES
-------
LIST OF FIGURES
Figure Page
S-l Interim and Alternate Sites for Arecibo S-5
S-2 Interim and Alternate Sites for Mayaguez S-6
S-3 Interim and Alternate Sites for Ponce S-8
S-4 Interim and Alternate Sites for Yabucoa S-9
1-1 Base Map for Arecibo Study Area 1-2
1-2 Base Map for Mayaguez Study Area 1-3
1-3 Base Map for Ponce Study Area 1-4
1-4 Base Map for Yabucoa Study Area 1-5
2-1 Locations of Mangroves, Landfills and Barren Areas
Near Arecibo 2-10
2-2 Locations of Mangroves, Landfills and Barren Areas
Near Mayaguez 2-11
2-3 Locations of Mangroves, Landfills and Barren Areas
Near Ponce 2-13
2-4 Locations of Mangroves, Landfills and Barren Areas
Near Yabucoa 2-14
2-5 Zone of Siting Feasibility for Arecibo 2-19
2-6 Zone of Siting Feasibility for Mayaguez 2-20
2-7 Zone of Siting Feasibility for Ponce 2-21
2-8 Zone of Siting Feasibility for Yabucoa 2-22
2-9 Interim and Alternate Sites for Arecibo 2-25
2-10 Interim and Alternate Sites for Mayauez 2-34
2-11 Interim and Alternate Sites for Ponce 2-43
2-12 Interim and Alternate Sites £or Yabucoa 2-53
3-1 Bathymetric Profile Offshore from Arecibo 3-8
3-2 Averaged Seasonal Temperature Profiles off
Punta Manati, 1973 and 1974 3-10
x
-------
LIST OF FIGURES (Continued)
Figure Page
3-3 Averaged Seasonal Salinity Profiles, by Season, off Punta
Manati, 1973 and 1974 3-11
3-4 Averaged Water Density Profiles, by Season, off Punta
Manati, 1973 and 1974 3-12
3-5 Surface Layer Transport, Arecibo Study Area 3-13
3-6 Subsurface and Near-Bottom Transport, Arecibo Study Area 3-15
3-7 Sediment Sampling Points and Identified Sea-Floor
Sediments off Arecibo 3-16
3-8 Secchi Disc Readings in Meters for Nearshore Waters Off
Barceloneta, July 1971 3-20
3-9 Averaged Dissolved Oxygen Depth Profiles, by Season, at
Punta Manati, 1973 and 1974 3-21
3-10 Averaged Reactive Phosphate Depth Profiles, by Season, at
Punta Manati, 1973 and 1974 3-23
3-11 Plot of Nitrate Vs. Standard Depth for the Fall Season
at Punta Manati, 1974 3-24
3-12 Living Marine Resources Near Arecibo 3-2d
3-13 Recreational Areas, Preserves and Shipwrecks Near Arecibo 3-29
3-14 Bathymetric Profiles Offshore from Playa Grande and
Punta Arenas 3-33
3-15 Averaged Temperature Profiles, by Season, off
Punta Higuero, 1973 and 1974 3-35
3-16 Averaged Salinity Profiles, by Season, off
Punta Higuero, 1973 and 1974 3-35
3-17 Averaged Density Profiles, by Season, off
Punta Higuero, 1973 and 1974 3-37
3-18 Surface Layer Transport, Mayaguez Study Area 3-41
3-19 Subsurface and Near-Bottom Transport, Mayaguez
Study Area 3-40
3-20 Sediment Sampling Point9 and Identified Sea-Floor
Sediments off Mayaguez 3-43
xi
-------
LIST OF FIGURES (Continued)
Figure Page
3-21 Averaged Dissolved Oxygen Depth Profiles, by Season, at
Punta Higuero, 1973 and 1974 3-45
3-22 Averaged Reactive Phosphate Depth Profiles, by Season, at
Punta Higuero, 1973 and 1974 3-47
3-23 Plot of Nitrate Vs. Standard Depth for the Fall Season,
at Punta Higuero, 1974 3-48
3-24 Living Marine Resources Near Mayaguez 3-52
3-25 Recreational Areas, Preserves and Shipwrecks Near Mayaguez 3-54
3-26 Bathymetric Profiles Offshore from Punta Cucharas and
Punta Pastillo 3-57
3-27 Averaged Temperature Profiles, by Season, off
Punta Verraco, 1973 and 1974 3-58
3-28 Averaged Salinity Profiles, by Season, off
Punta Verraco, 1973 and 1974 3-59
3-29 Averaged Density Profiles, by Season, off
Punta Verraco, 1973 and 1974 3-60
3-30 Surface Layer Transport, Ponce Study Area 3-62
3-31 Subsurface and Near-Bottom Transport, Ponce
Study Area 3-63
3-32 Sediment Sampling Points and Identified Sea-Floor
Sediments off Ponce 3-66
3-33 Secchi Disk Readings in Meters for Nearshore Waters
off Ponce, September 1971 3-69
3-34 Secchi Disk Readings in Meters for Nearshore Waters
off Guayanilla, October 1971 3-70
3-35 Averaged Dissolved Oxygen Depth Profiles, by Season, at
Punta Verraco, 1973 and 1974 3-71
3-36 Averaged Reactive Phosphate Depth Profiles, by Season, at
Punta Verraco, 1973 and 1974 3-73
3-37 Averaged Nitrate Depth Profiles, for the Summer and Fall
Season, at Punta Verraco, 1973 and 1974 3-74
3-38 Living Marine Resources Near Ponce 3-78
xii
-------
LIST OF FIGURES (Continued)
Figure Page
3-39 Recreational Areas, Preserves and Shipwrecks Near Ponce 3-80
3-40 Bathymetric Profiles Offshore from Punta Tuna and
Punt a Yeguas 3-83
3-41 Spring and Seasonal Temperature Profile for Deepwater Site,
Cabo Mala Pascua and Punta Verraco 3-85
3-42 Spring and Seasonal Solubility Profile for Deepwater Site,
Cabo Mala Pascua and Punta Verraco 3-86
3-43 Averaged Water Density Profiles, by Season, Offshore from
Cabo Mala Pascua, 1973 and 1974 3-87
3-44 Surface Layer Transport, Yabucoa Study Area 3-89
3-45 Subsurface and Near-Bottom Transport, Yubucoa
Study Area 3-91
3-46 Sediment Sampling Points and Identified Sea-Floor
Sediments off Yabucoa 3-93
3-47 Suspended Particulate Matter Concentrations and Turbidity
Profiles at the Roosevelt Roads Naval Station Disposal Site.... 3-96
3-48 Averaged Dissolved Oxygen Depth Profiles, by Season, at
Cabo Mala Pascua, 1973 and 1974 3-97
3-49 Averaged Reactive Phosphate Depth Profiles, by Season, at
Cabo Mala Pascua, 1973 and 1974 3-99
3-50 Averaged Nitrate Depth Profiles, for the Summer and Fall
Season at Cabo Mala Pascua, 1974 3-100
3-51 Composite Silica Depth Profiles of all University of
Puerto Rico OTEC Cruises, September 1975 to May 1976 3-101
3-52 Living Marine Resources Near Yabucoa 3-105
3-53 Recreational Areas, Preserves and Shipwrecks Near Yabucoa 3-106
4-1 Maps of Recreational Areas and Public Resources for the
Interim and Alternate Sites Near Arecibo Showing Sediment
Deposition Concentration 4-9
4-2 Sediment Deposition Relative to Arecibo Living Resources 4-12
xiii
-------
LIST OF FIGURES (Continued)
Figure Page
4-3 Maps of Recreational Areas and Public Resources for the
Interim and Alternate Sites Near Mayaguez Showing Sediment
Deposition Concentration 4-13
4-4 Sediment Deposition Relative to Mayaguez Living Resources 4-15
4-5 Maps of Recreational Areas and Public Resources for the
Interim and Alternate Sites Near Ponce Showing Sediment
Deposition Concentration 4-18
4-6 Sediment Deposition Relative to Ponce Living Resources 4-19
4-7 Maps of Recreational Areas and Public Resources for the
Interim and Alternate Sites Near Yabucoa Showing Sediment
Deposition Concentration 4-22
4-8 Sediment Deposition Relative to Yabucoa Living Resources 4-24
FIGURES IN APPENDIX VOLUME
C—1 Locations of Possible Land-Based DMDS Near Arecibo C-20
C-2 Locations of Possible Land-Based DMDS Near Mayaquez C-28
C-3 Locations of Possible Land-Based DMDS Near Ponce C-37
C-4 Locations of Possible Land-Based DMDS Near Yabucoa C-44
D-l Sequence of Evaluation Procedures and Toxicity Testing for
Proposed Discharge of Dredged Material into Ocean Waters D-4
E-l Coral Species Richness as a Function of Sedimentation Rate,
Guam E-l 6
F-l Bathymetric Profiles Offshore from Punta Cucharas and
Punta Pastillo
F-2 Seasonal Variation of Temperature and Salinity off
Punta Verraco, 1973 and 1974
F-3 Averaged Salinity Profiles, by Season, off
Punta Verraco, 1973 and 1974
xiv
-------
APPENDIX FIGURES (Continued)
Figure Page
F-4 Averaged Water Density Profiles, by Season, off
Punta Verraco, 1973 and 1974 F-8
F-5 Averaged Temperature Profiles, by Season, off
Punta Verraco, 1973 and 1974 F-9
F-6 Cross-Shelf Density Sections off Ponce, September 1971 F-10
F-7 Cross-Shelf Sections off Guayanilla, October 1971 F-ll
F-8 Surface Layer Transport, Ponce Study Area F-16
F-9 Subsurface Current Profile (Station 42) Near Ponce Harbor
Dredged Material Disposal Site F-17
F-10 Geostrophic Velocity from Puerto Rico to Venezuela
Along 67°W, October 1972 F-19
F-ll Subsurface and Near-Bottom Transport, Ponce
Study Area F-20
F-12 Bathymetric Profiles Offshore from Punta Tuna and
Punta Yeguas F-21
F-13 Annual Frequency Distribution of Significant Wave Heights
and Wave Periods, Area 23, Viegues, Puerto Rico F-23
F-14 Wave Height Versus Wind Speed, Area 23, Viegues, Puerto Rico... F-24
F-15 Temperature-Salinity Plot for All University of Puerto Rico
OTEC Cruises F-27
F-16 Averaged Water Density Profiles, by Season, off
Cabo Mala Pascua, 1973 and 1974 F-29 ~
F-17 Spring and Seasonal Salinity Profile for Deepwater Site,
Cabo Mala Pascua, and Punta Verraco F-30
F-18 Spring and Seasonal Temperature Profile for Deepwater Site,
Cabo Mala Pascua, and Punta Verraco F-31
F-19 Seasonal Variations of Mixed Layer Depth off Punta Tuna,
Puerto Rico F-32
F-20 Surface Layer Transport, Yabucoa Study Area F-37
F-21 Subsurface and Near-Bottom Transport, Yabucoa Study Area F-39
xv
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APPENDIX FIGURES (Continued)
Figure Page
F-22 Subsurface Current Profile (Station 41) Near Yabucoa Harbor
Dredged Material Disposal Site F-41
F-23 Dynamic Height Fields (cm) for May 1980 and September 1980 F-43
xv i
-------
LIST OF TABLES
-------
LIST OF TABLES
Table Page
2-1 Comparision of Representative Costs for Ocean and
Non-Ocean Disposal Options 2-4
2-2 Comparative Summary of Environmental Consequences of
Land-Based Alternatives 2-5
2-3 Summary of Land-Disposal Site Suitability at Arecibo,
Mayaguez, Ponce, and Yabucoa 2-7
2-4 Comparison of Ocean Dredged Material Disposal
Sites for Arecibo 2-26
2-5 Comparison of Ocean Dredged Material Disposal
Sites for Mayaguez 2-36
2-6 Results of Bioassays Conducted on Three Sediments from
Ponce Harbor 2-45
2-7 Comparison of Ocean Dredged Material Disposal
Sites for Ponce 2-47
2-8 Results of Bioassays Conducted on Three Sediments
from Yabucoa Harbor 2-55
2-9 Comparison of Ocean Dredged Material Disposal Sites
for Yabucoa 2-57
3-1 Correlation Matrix for Sediment Grain Size, Biological
Parameters, and Station Depth Offshore of Arecibo 3-26
3-2 Correlation Matrix for Sediment Grain Size, Biological
Parameters, and Station Depth Offshore of Mayaguez 3-51
3-3 Correlation Matrix for Sediment Grain Size, Biological
Parameters, and Station Depth Offshore of Ponce..... 3-76
3-4 Correlation Matrix for Sediment Grain Size, Biological
Parameters, and Station Depth Offshore of Yabucoa 3-103
3-5 Taxonomic List of Species Identified in the Study Area
of the Puerto Rico Dredged Material Disposal Sites 3-110
3-6 Taxonomic List of Threatened and Endangered Species
Identified in the Study Area of the Puerto Rico Dredged
Material Disposal 3-113
4-1 Summary of the Adverse Effects of Suspended Sediments on
Marine Organisms
xvii
-------
LIST OF TABLES (CONTINUED)
5-1 Contributors to the Environmental Impact Statement 5-2
TABLES IN APPENDIX VOLUME
B-l Summary of Dredging Frequencies and Volumes of Material
Dredged B-2
B-2 Dredging History, Arecibo Harbor B-4
B-3 Dredging History, Mayaguez Harbor B-7
B-4 Dredging History, Ponce Harbor B-10
B-5 Dredging History, Yabucoa Harbor B-13
C-l Comparison of Representative Costs for Ocean and Non-ocean
Disposal Options C-2
C-2 Potential Problems from the Use of Diked Containment
Areas (Hydraulic Fill) for DM Disposal C-7
C-3 Characteristics of Landfills Near Arecibo C-22
C-4 Characteristics of Barren Areas Near Arecibo C-23
C-5 Characteristics of Landfills Near Mayaguez C-29
C-6 Characteristics of Barren Areas Near Mayaguez C-32
C-7 Characteristics of Landfills Near Ponce C-38
C-8 Characteristics of Barren Areas Near Ponce C-39
C-9 Characteristics of Landfills Near Yabucoa C-45
E-l Relative Sensitivities to Sedimentation of Some
Common Caribbean Coral Species E-8
E-2 Summary of Studies Evaluating the Impact of Burial on Corals... E-9
E-3 Summary of Studies Evaluating the Impact of Sedimentation
on Corals E-ll
E-4 Summary of Studies Evaluating the Impact of Turbidity on
Coral E-19
F-l Summary of Hydrographic Data, Ponce F-4
F-2 Seasonal Variation of Pycnocline Depth, Ponce F-12
xviii
-------
LIST OF TABLES (CONTINUED)
F-3 Summary of Circulation Data, Ponce F-14
F-4 Sources of Hydrographic Data, Yabucoa F-26
F-5 Summary of Circulation Data, Yabucoa F-34
F-6 Mean Current Speed and Direction Offshore of Punta Tuna
and Yabucoa F-40
H-l Feeding Types of Polychaetes at Station 2
(Mayaguez Interim DMDS) H-2
H-2 Feeding Types of Polychaetes at Station 3
(Mayaguez Interim DMDS) H-3
H-3 Feeding Types of Polychaetes at Station 1
(Ponce Interim DMDS) H-4
H-4 Feeding Types of Polychaetes at Station 7
(Ponce 1 nmi South of Alternate Site 2) H-5
H-5 Feeding Types of Polychaetes at Station 8
(Ponce 1 nmi East of Alternate Site 2) H-6
xix
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1. PURPOSE OF AND NEED FOR ACTION
-------
1. PURPOSE OF AND NEED FOR ACTION
1.1 PURPOSE OF ACTION
The harbors of Arecibo, Mayaguez, Ponce, and Yabucoa are important to the
commercial and industrial development of Puerto Rico. Access of ships to the
harbors depends on periodic dredging to maintain the authorized depths. In
the past, materials from these dredging operations was disposed of at interim
designated ocean disposal sites. In 1980, the National Wildlife Federation
(NWF) challenged the practice of using interim ocean disposal sites pending
completion of long term studies and final designation pursuant to the Marine
Protection, Research and Sanctuaries Act of 1972 (MPRSA), as amended (86 Stat.
1052, 33 USCA Part 1401 et seq., 45 Fed. Reg 3053 Jan 16, 1980). In resolving
the law suit, the EPA and the U.S. Army Corps of Engineers (COE) entered into
a consent decree with the NWF to take steps to designate final ocean dredged
material disposal sites (DMDSs) for certain sites with interim designation.
Although these four Puerto Rican interim disposal sites were not covered by
the consent decree, EPA is responding to COE's need to have designated ocean
dredged material disposal sites in Puerto Rico. EPA is undertaking studies
preparatory to designating a final DMDS at each harbor.
The action proposed in this environmental impact statement (EIS) is the
final designation of environmentally acceptable ocean disposal sites for
materials dredged from the harbors and areas surrounding Arecibo, Mayaguez,
Ponce and Yabucoa. The environmental studies and final designation are being
conducted in accordance with the requirements of MPRSA; EPA's implementation
of the ocean dumping regulations (ODR) and ODR criteria (40 CFR 220-229); the
National Environmental Policy Act (NEPA); and other applicable Federal legis-
lation. Figures 1-1 through 1-4 show the study areas and interim ocean
disposal sites for each harbor.
1.2 ARMY CORPS OF ENGINEERS NEED FOR ACTION
Approvals of private permit requests and COE-initiated projects for the
ocean dumping of dredged material are made by the U.S. Secretary of the Army
in accordance with regulatory criteria established by EPA. Section 103 of
1-1
-------
66°30'
* Depth* In fathoms
FIGURE 1-1. BASE MAP FOR ARECIBO STUDY AREA
1-2
-------
* Depths in fathoms
FIGURE 1-2. BASE MAP FOR MAYAGUEZ STUDY AREA
-------
66°30'
aeao
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* D«ptha In fathoms
FIGURE 1-3. BASE MAP FOR PONCE STUDY AREA
1-4
-------
66°00'
* Depths In fat
boas
FIGURE 1-4. BASE MAP FOR YABUCOA STUDY AREA
1-5
-------
MPRSA requires COE to consider the effects of ocean disposal of dredged
material on human health and welfare, or amenities, and on the marine environ-
ment, ecological systems, or economic potentialities. The 1977 Ocean Dumping
Criteria gave EPA and COE three years to complete studies on 127 dredged
material ocean dumpsites. EPA initiated studies on sites, and in 1980 pub-
lished an amendment to the criteria extending the interim designation of 46
unstudied dumpsites for up to three more years. The amendment also extended
the interim designation of 85 additional unstudied dredged-material dumpsites
for an indefinite period of at least three years.
In February 1980 the NWF filed suit against the EPA and the COE in an
attempt to persuade them to take steps to complete ocean dumpsite designation
for the identified sites. These did not include the four sites considered by
this EIS. The lawsuit was settled by a stipulation of settlement and dismis-
sal in which COE agreed to issue a guidance memorandum directed to district
and division engineers specifying procedures to be followed in determining
whether to issue an ocean dumping permit for disposal of dredged material at
interim designated dumpsites. The directive from COE Headquarters required
the district engineer, before authorizing dumping at interim-approved dump-
sites, to assess reasonable availability of alternatives to dumping there.
Specifically, the engineer should consider:
• The feasibility and practicability of using a finally designated site
or a more fully studied dumpsite in lieu of an unstudied dumpsite.
• The feasibility and practicability of deferring the decision on ocean
dumping at the proposed site until site study and/or final designation
efforts have been completed, and
• The availability of practicable alternative locations, and methods of
disposal or recycling (i.e., land based alternatives) of the material
proposed to be ocean-dumped.
Since 1977, the COE in Puerto Rico has used ocean dredged material dis-
posal sites designated by EPA on an interim basis. Use of these sites has
been an essential element of COE compliance with the requirements of MPRSA and
its ability to carry out its statutory responsibility for maintaining safe
navigation in the harbors of Puerto Rico. To continue to maintain these
1-6
-------
waterways COE considers it essential that EPA identify, evaluate and perma-
nently designate environmentally acceptable ocean dredged material disposal
sites. These sites will be used after reviews of each project and permit
application have established that the proposed activity is in compliance with
the criteria and requirements of EPA and COE regulations.
1.3 CORPS OF ENGINEERS LOCAL NEED FOR ACTION
The harbors of Arecibo, Mayaguez, Ponce, and Yabucoa are essential to the
continued commercial and industrial growth of Puerto Rico. Ocean-going ships
require channels, berths and turning basins that are, at a minimum, about 6
fathoms (10 meters deep). Periodic maintenance dredging is essential for the
continued use of these harbors. Each harbor is subject to gradual shoaling
and filling in as a result of sediment deposition from rivers and storm-waves.
Without dredging, the harbors would eventually become inaccessible to large
commercial vessels. Future dredging actions may include both maintenance
dredging and harbor channel deepening.
The following sections discuss the specific dredging needs of each
harbor.
1.3.1 Need for Dredging, Arecibo
Arecibo is subject to flash flooding during the rainy season. The Rio
Grande de Arecibo and its tributaries, which flow into the harbor, contribute
heavily to sediment deposition from May to October. In addition, Arecibo is
subject to periodic shoaling because of its exposure to the periodic heavy
wave conditions characteristic of the north coast.
Arecibo is an important harbor for ships transporting pharmaceutical
supplies and products from a number of pharmaceutical plants located southeast
of the port. The amount of dredged material to be removed is likely to be on
the order of 75,000 to 150,000 cubic meters (100,000 to 200,000 cubic yards)
every three to five years (these estimates are based on data presented in
Appendix B).
1-7
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1.3.2 Need for Dredging, Mayaguez
Flash flooding during the rainy season contributes heavily to sediment
deposition in the Mayaguez coastal embayment. The Port of Mayaguez is the
principal harbor on Puerto Rico's west coast. A total of 321,764 tons of
freight traffic moved through the harbor in 1983 (COE 1981). Dredging volumes
in this harbor have varied in past years; the amount of dredged material to be
removed is expected to range from 15,000-114,000 cubic meters (20,000 to
150,000 cubic yards) every two to five years (Appendix B).
1.3.3 Need for Dredging, Ponce
Ponce is one of the three principal Puerto Rican harbors able to receive
large ocean-going commercial vessels; only the harbor of San Juan handles more
tonnage. A total of 854,651 tons of freight traffic (five percent of the
waterborne commerce of the island) moved through the Port of Ponce in 1981
(COE, 1983).
There are public and private port facilities at Ponce. The municipal
pier and bulkhead area have six ship berths owned and operated by the
Municipal Port Authority of Ponce. Five of the berths have depths of about 30
feet and are from 350 to 500 feet long. Adjacent to the municipal bulkhead
are a variety of commercial facilities that depend on the port: seven muni-
cipal warehouses, a private tuna packing plant, and a 1.6 hectare (4 acre)
cargo storage area (COE 1975).
Two rivers, Rio Matilde and Rio Portuques, empty into Ponce Harbor, and
the mouth of a third, the Rio Bucana, is about one mile east of the port.
These river basins are among the steepest on the island. Therefore, the
short, intense showers of the wet season (May through October) result in
floods that transport large volumes of sediments to Ponce.
The amount of dredged material that may have to be removed is expected to
be on the order of 75,000 to 150,000 cubic meters (100,000-200,000 cubic
yards) of sediment every three years (Appendix B). In addition, COE may need
to dispose of an unknown quantity of dredged materials from the neighboring
1-8
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Guayanilla Bay, a harbor whose dredged materials have in the past been dumped
at the Ponce DMDS. At Guayanilla, dredging is necessary to keep the harbor
open to ocean-going petroleum tankers and local oil barges (COE 1981a).
1.3.4 Need for Dredging, Yabucoa
Yabucoa is the only commercial harbor in southeastern Puerto Rico. Un-
like the other three harbors addressed in this EIS, Yabucoa is maintained and
operated by the Puerto Rico Port Authority. Cargos at the harbor are mainly
crude oils destined for the Sun Oil refinery in Yabucoa.
The amount of dredged material that may have to be removed is expected to
be on the order of 380,000 to 450,000 cubic meters (500,000 to 600,000 cubic
yards) every five to six years (Appendix B). In addition, the Puerto Rico
Port Authority will need to dispose of an unknown quantity of materials from
the neighboring harbor and channel at Puerto Las Mareas (Guayama Harbor) (COE
1981b), and the COE will need to dispose of materials from the harbor channels
of the Roosevelt Roads naval base (EPA 1981).
1.4 ENVIRONMENTAL PROTECTION AGENCY'S NEED FOR ACTION
The transportation and dumping of materials in ocean waters is regulated
under Title I of the Marine Protection, Research and Sanctuaries Act of 1972
(MPRSA). Title I requires that the EPA Administrator and the U.S. Secretary
of the Army establish permit programs to exclude from the ocean all dredged
and nondredged material that might result in unreasonable degradation or
endangerment of the marine environment or human health. COE is responsible
for dredged-material permits. EPA is responsible for all other wastes. Title
I requires EPA to establish criteria, based on the nine evaluation factors
specified in MPRSA Section 102(a), to review and evaluate requests for per-
mits. Section 102(c) of Title I authorizes EPA to consider these criteria in
designating ocean disposal sites or times for dumping dredged and nondredged
material. The statute provides for the case-by-case evaluations of ocean
dumping permit applications, and dumping is approved only when there is an
affirmative showing of no unreasonable degradation.
1-9
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To meet its responsibilities under MPRSA, EPA developed Ocean Dumping
Regulations (ODR) and criteria (1973) and revised them in January 1977 (40 CFR
220-229). These regulations set forth procedures and criteria for:
• Evaluating dredged material disposal permit applications (Part 225),
• Enforcing permit conditions (Part 226),
• Evaluating proposed actions for environmental impacts (Part 227), and
• Designating and managing disposal sites for ocean dumping (Part 228).
Part 228 establishes the five general and eleven specific criteria that
are used to evaluate the environmental acceptability of potential DMDSs.
To carry out its statutory responsibility of maintaining the nation's
navigation waterways while complying with the provisions of MPRSA and other
applicable federal statutes, COE needs designated DMDSs in Puerto Rico.
In response to this need, EPA has initiated the necessary studies to
select, evaluate, and designate the most suitable sites for the ocean disposal
of dredged material from the above four harbors. This document has been pre-
pared to provide relevant information needed to assess the impacts associated
with the final designation of an DMDS for each harbor.
1.5 INTERNATIONAL CONSIDERATIONS
The principle international agreement governing ocean dumping is the
convention on the Prevention of Marine Pollution by Dumping of Wastes and
Other Matter, commonly known as the London Dumping Convention (LDC), which
became effective in August 1975 upon ratification by 14 contracting countries
including the United States (26 UST 2403: TIAS 8165). There are now 44 con-
tracting parties. Designed to control dumping of wastes in the ocean, the
Convention specifies that contracting nations will regulate disposal in the
marine environment within their jurisdiction and prohibit disposal without
permits. Disposal of certain hazardous materials (e.g., radiological, bio-
logical, and chemical warfare agents, and high-level radioactive matter) is
1-10
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completely prohibited. Certain other materials (e.g., cadmium, mercury,
organohalogens and their compounds, oil, and persistent synthetic or natural
materials that float or remain in suspension) are also prohibited as other
than trace contaminants unless they are rapidly rendered harmless by physical,
chemical, or biological processes in the sea. Other materials (e.g., arsenic,
lead, copper, zinc, cyanides, fluorides, organosilicon, and pesticides) not
specifically prohibited will require the issuance of a special permit. The
nature and quantities of all ocean-dumped material, and the circumstances of
disposal, must be periodically reported to the Inter-Governmental Maritime
Consultative Organization (IMCO) which is responsible for administration of
the Convention.
The criteria of the U.S. Ocean Dumping Regulations are based on the pro-
visions of the LDC and include all the considerations listed in Annexes I, II,
and III of LDC. Agreements reached under the LDC allow exclusions from bio-
logical testing for dredged material from certain locations. These agreements
are also reflected in the U.S. ocean dumping criteria. Thus, when a material
is found to be acceptable for ocean dumping under the U.S. ocean dumping
criteria, it is also acceptable under the LDC.
1-11
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2. ALTERNATIVES INCLUDING THE PROPOSED ACTION
-------
2. ALTERNATIVES INCLUDING THE PROPOSED ACTION
2.0 INTRODUCTION
The proposed actions are the permanent designations of ocean dredged
material disposal sites at Arecibo, Mayaguez, Ponce, and Yabucoa, Puerto Rico.
Alternatives to the proposed action must be evaluated to meet the
requirements of the National Environmental Policy Act (NEPA).
Alternatives considered for each harbor were:
• No-Action: The no-action alternative to final designation is to
refrain from designating ocean disposal sites. This would result in
continued disposal at the interim ocean disposal sites.
• Non-Ocean Disposal: The non-ocean disposal alternatives to be evalu-
ated include land disposal, recycling, and reuse options.
• Designation of the interim ocean disposal site as the site for con-
tinuing use.
• Designation of one of several alternative ocean disposal sites as the
site for continuing use.
2.1 NO-ACTION ALTERNATIVE
The no-action alternative to the proposed action would be to refrain from
designating ocean sites for the disposal of dredged material from the harbors
and areas surrounding Arecibo, Mayaguez, Ponce, and Yabucoa, Puerto Rico. COE
uses an interim designated site for each harbor. By selecting the no-action
alternative COE would not have EPA-designated ocean disposal sites available,
but would continue to use the interim designated sites.
2.2 NON-OCEAN DISPOSAL ALTERNATIVE
Dredged material from the harbors is primarily fine-grained material
(silt and clay). The land-based alternatives for the disposal of fine-grained
material that were evaluated included:
2-1
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• Placement as hydraulic fill
• Formation of wetland habitats, and
• Use as cover material in landfills and barren areas.
This section discusses the need for evaluating land-based dredged
material disposal, the types of disposal options available, and the poten-
tially suitable sites at each of the four harbors.
2.2.1 Introduction
Disposal of dredged material on land is sometimes technically, economic-
ally, and environmentally preferable to disposal at sea. In Puerto Rico,
dredged material has been disposed of by both methods. The predominant land-
based disposal method has been hydraulic filling, which was used to produce
land for industrial development and to fill in wetlands (COE 1975, Colon
1984).
2.2.2 Justification for Evaluation of Land Based Disposal
The action proposed in this EIS is the final designation of environ-
mentally acceptable ocean disposal sites for dredged materials. As required
by 40 CFR Part 6 — Implementation of Procedures on the National Environmental
Policy Act of 1969, an EIS must evaluate possible alternatives to the proposed
action. The only possible alternative (other than no-action) to the designa-
tion of ocean disposal sites would be land-based disposal. Land-based options
are examined in the following sections of this chapter.
2.2.3 Available Land-Based Disposal Methods
Disposal of dredged material on land in Puerto Rico is more expensive
than ocean disposal. Suitable sites near the harbors are limited and expen-
sive because of their potential commercial value. Each proposed disposal
action would need a site-specific impact assessment and engineering study.
There is a high potential for environmental damage if the disposal area is
improperly designed, constructed, or operated.
2-2
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2.2.3.1 Factors Affecting Selection of Land-Based Disposal Alternatives
The suitability and availability for land-based disposal options depend
on:
• The costs of land, site preparation, and transportation of material to
the site.
• The characteristics of the dredged material.
• The environmental and socioeconomic conditions near the harbor.
Table 2-1 compares the dredged material disposal costs of various dis-
posal alternatives. These general data indicate that several land-based
alternatives can be cost-competitive with ocean disposal if suitable sites can
be located, and if land prices at the sites are lower than the average prices
for commercial land near the harbors. However, land is at a premium in Puerto
Rico, and land near the harbors considered in this EIS is expensive, ranging
from $15 to $30 per square meter, ($60,000 to $120,000 per acre, Franciscas
Realty 1984). It is specifically outside of the scope of an EIS to evaluate
relative dollar values of environmental resources, or impacts upon those
resources, except for the purposes of establishing absolute feasibility of a
disposal option.
Land values in this range indicate that land disposal will not be a
feasible option in most Puerto Rican locations, and that particularly low-cost
land disposal options such as use of barren areas, or abandoned mining pits,
or productive disposal options such as valuable wetland creation, are the only
feasible land-based alternatives. An evaluation of environmental acceptabil-
ity and availability of such alternatives in the regions surrounding the four
harbors is presented below. A summary of the conclusions of these evaluations
is given in Section 2.2.4.
United States Geological Survey (USGS) topographic maps of the four
harbors, and studies of waste disposal in Puerto Rico were used to locate
sites near each harbor that meet the appropriate disposal site criteria. The
results of this analysis are presented in Table 2-2.
2-3
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TABLE 2-1. COMPARISON OF REPRESENTATIVE COSTS FOR OCEAN AND
NON-OCEAN DISPOSAL OPTIONS
DM Disposal Technique
Partial Cost
Hod i f ication
Fu 11 Disposal Cost
cy
Ocean Dispoaal-
* Clamshell dredge and barge acow
(Mayaquez, PR)
0.7I512'
to 2.00 cy/nmi
Assuratng I
tt.5 nmi to
DHDS
5 to
ocean
Representee ive cost
"~5/cy (2)
$3.00 cy to
b .Ott/ c y
•
COE hopper dredge (national average)
(4)
$0.20/cy/nmi
Assuming 1
b.5 nmi to
DMDS
5 to
ocean
0.45 to $ I . 70/c y
a
Barge acow or hopper dredge, unspecified
$0 . 1 59 3/c y/nmi^
^Assuming
8.5 nmi to
DHDS
.5 to
ocean
0.24 to $1 . J5/cy
Land Disposal-
•
Use of diked containment areas on land
2.5 t icnea cost of
open water dia^j
posal is depen
dent on transport
distance and site
size.
Representative costs
•
Harsh production, without revegetation
Dikes coat from
$30,000 to $5 million
for sites 10 acres
to 2500,acres in size
in 1972
$0.29-0 . 7(t/cy( 1 '
•
Marsh production, with revegetation
$4.50("*
•
Dewatering at a regional site, then
use as landfill cover material
$13 to $21/cyll)
•
Pipeline transport to landfill or
or barren area
1 mile, without
booster to 2 miles,
with booster pump.
$ 1 .bS to SJ.ua/cy15'*
•
Use for beach nourishment via pipeline
to beach, transport 10 nmi or less
2600 feet of P>PSJ
1 ine S 1. 1 22/cy
$2.70 to h.JO/cy
using transport costs
given above
•
Use of DH to produce containment islands
2 to 3 1/2 times
cost of ocean
d i sposal
OD * 2 -
0D x 3.5 -
0.50 to 21.JO/cy
Source!:
(1) Coch et al. 1983
(2) Peri. coon. Gerald Atman, COE Jacksonville, FL, June 26, 1984
(3) EPA 1981 (Vieques EIS)
(4) Pers. cm. Dave Mathis, COE Ft. Belvoir, VA, June 20, 1984
(5) Brady, 1976
(6) Pers. com. Dave Mathi9, COE Ft. Belvoir, VA, June 29, 1984
(7) Knutson 1976
* Converted from original (outdated) coat by using factors presented in Englesnidnn (1984)
2-4
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TABLE 2-2. COMPARATIVE SUMMARY OF ENVIRONMENTAL CONSEQUENCES OF
LAND-BASED ALTERNATIVES
Evaluation
Criteria
Placement as
Hydraulic Fill
Formation of
Wetlands
Use as Cover
Material in
Landfills
Use as Cover
Material In
Barren Areas
Air Impacts
Emission of
pollutants (CO,
particulates,
hydrocarbons,
NO and SO )
X X
from fuels
used by earth-
moving equipment
during dike con-
struction. Dust
from unvegetated
dry hydraulic fill.
Possible dust
from dry dredged
material prior
to establish-
ment of complete
vegetative cover.
Dust emissions
during and after
cover material
placement likely
until vegetative
cover established
Dust emissions
during and after
cover material
likely until
vegetative cover
established.
Water Impacts
Surface water
impacts minor if
effluent is dis-
charged into salt
water and if dikes
remain structurally
sound; groundwater
impacts minor if
site overlies
saline or brackish
groundwater.
Surface water
impacts minor if
effluent is dis-
charged into salt
water and if dikes
remain structurally
sound; groundwater
impacts minor if
site overlies
saline or brackish
groundwater.
Surface water
impacts likely
because most
landfills are
not near salt
water. Ground-
water contam-
ination with
salt is likely
because most
landfills over-
lie nonsaline
water
Surface water
impacts likely
because most
landfills are
not near salt
water. Ground-
water contam-
ination with
salt Is likely
because most
landfills over-
lie nonsaline
water
Land Impacts
Would require
long tern (10
year or more)
commitment of
2 to 37 acres
per harbor.1
Would require
decreasing
size of nearby
lagoons or
protected,
shallow-water
by 4 to 37 acres
per harbor.
May cause
substantial
Increase in
use rates of
existing land-
fills.
Would fill
In and cover
abandoned or
mined-out
portions of
quarries or pits,
and allow some
types of land re-
use after fill
material has
consolldated.
(1) Assuming a dredged material volume of from fi9,100 to 600,000 cubic yards and a dredged material
depth of from 10 to 20 feet (3 to 6 meters).
(2) Assuming a dredged material volume of from 69,100 to 600,000 cubic yards and a dredged material
depth of from 6 to 10 feet (2 to 3 meters).
2-5
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An analysis was conducted to determine the specific requirements for
land-based dredged material disposal sites, using various dredged material
disposal techniques. These requirements are described in detail in Appendix
E.
The site-suitability analysis was intended only to locate potentially
suitable sites for dredged material disposal. The analysis did not account
for the possibility that suitable sites may not be available for use because
of owner opposition or incompatible current land use, or that local opposition
may preclude the use of certain dredged material disposal techniques.
Table 2-3 also lists the number of suitable sites near each harbor for
these potential disposal options. At Arecibo and Yabucoa, there are suitable
sites for only one of the four disposal options. At Mayaguez and Ponce three
of the four options are considered feasible.
2.2.3.2 Land-Based Disposal Options for Fine-Grained Sediments
The dredged material from all of the harbors is primarily fine-grained
material (containing high percentages of silt and clay); this factor limits
the land-based disposal alternatives to the following options:
• Placement as hydraulic fill
• Formation of wetland habitats
• Use as cover material in landfills or barren areas.
The disposal process for each of these methods are described below. Data
on historical use of each method and their respective advantages and disadvan-
tages are presented in Appendix C.
Placement as Hydraulic Fill — Hydraulic filling is a dredged material
disposal method that involves placing the dredged material as a slurry in a
contained area on land. Hydraulic filling requires the construction of dikes
around a large, flat area that is close to a navigable waterway. The dike
must also contain an adjustable dam called a weir. The dredged material is
2-6
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NJ
I
TABLE 2-3. SUMMARY OF LAND-DISPOSAL SITE SUITABILITY AT ARECIBO, MAYAGUEZ, PONCE AND
YABUCOA
Harbor
Number of
Potentially Suitable Sites for Each Land-Based Disposal Method
Placement
Hydraulic
Fill
as Formation
of Wetlands
Cover Material
for Landfills
Cover Material for
Barren Areas
Arecibo
0
0
0
1
Mayaguez
0
1
1-2
1
Ponce
1
1
0
4
Yabucoa
1
0
0
0
-------
pumped as a slurry into the diked containment area and the solids are allowed
to settle out of the water. The clear water flows out over the weir and into
a nearby water body. If the dredged material is sandy, the solids settle out
rapidly; the water flows out readily and a stable material results. If the
dredged material is clay, the solids settle out very slowly, and sufficient
drainage to produce a stable material can take decades (Harrison and Chisolm
1974, McCarthy 1977).
Formation of Wetland Habitats — This disposal option involves careful
site selection, preferably at an elevation within the tidal range, near
existing marshes, and in areas protected from high wave energies (Patin 1976;
Holloway 1976; Smith 1976). To form a marsh, dikes are built along the
perimeter of the site to an elevation that is higher than the highest tide
plus a few feet of freeboard to prevent dike erosion by storm waves. The
dredged material is hydraulically placed and the site may eventually be
revegetated, after sufficient dewatering has occurred. Mangroves are a common
type of vegetation used in the formation of wetland habitats in Puerto Rico.
Other types of emergent vegetation can be used as well.
Use as Cover Material in Landfills or Barren Areas — The use of dredged
material as a cover material for landfills or barren areas has been suggested
as a feasible alternative to ocean disposal. A study of disposal alternatives
for dredged material from the New York Harbor area describes two processes by
which the dredged material could be handled. In one process, the material
could be transported as a slurry through a pipeline from the barge to the
landfill or barren area (the disposal site) if the disposal site is within
5 miles of a navigable waterway, and if the topography between the barge off-
loading point and the disposal site is not too variable or steep. Once at the
disposal site, the dredged material would have to be placed in a diked con-
tainment area or in thin layers over large areas to allow drying, prior to
vegetating (Coch et at. 1983).
The second possible process requires the use of a large diked containment
area. The dredged material would be partially dried at this facility using
COE-developed dredged material drying techniques. The material would then be
trucked to landfills or barren areas (Coch et al. 1983).
2-8
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2.2.4 Land-Based Options for Each Harbor
The availability of land-disposal options is evaluated in this section
independently for each harbor. A summary of conclusions for all harbors is
given in Section 2.2.5.
2.2.4.1 Land-Based Disposal Options for Arecibo
The locations of the mangroves, landfills, and barren areas identified
near Arecibo are shown in Figure 2-1. The appropriateness of each site was
evaluated, taking into account the site's location relative to Arecibo, its
distance from the coast, its elevation, its geohydrology, and other factors.
Details of these analyses are presented in Appendix C.
There are significant disadvantages associated with all of the possible
alternative disposal options. Hydraulic fill locations, if any suitable sites
can be located and acquired, are likely to be limited in size and very expen-
sive. Wetland production would be hindered by ocean conditions (high wave
energies) and lack of suitable sites. Application of dredged material on land
as a cover material could degrade groundwater quality in the area particularly
at sites far from the coast. The only option that might be technically,
environmentally, and economically feasible would be use of one of the barren
areas, if this site does contain a series of abandoned sand pits, as indicated
in one reference map (as discussed in Appendix C, p. C-21). Environmental
studies would have be done to determine whether that barren area would have
the capacity to receive Arecibo dredged material, and it is likely that
environmental and economic factors would mitigate against use of this
alternat ive.
2.2.4.2 Land-Based Disposal Options for Mayaguez
The locations of the mangroves, landfills, and barren areas identified
near Mayaguez are shown in Figure 2-2. Appendix C presents details of site
evaluat ions.
The use of land-based disposal alternatives near Mayaguez may be techni-
cally feasible. No potential sites for hydraulic filling were identified,
2-9
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ATLANTIC OCEAN
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m
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^ i#r
LANDFILL ~
PIT OR QUARRY ^
MANGROVE SWAMP jvf-
OTHER SWAMP
MIMI «_
Kilo-n««»r< 0 1 » 3
CONVERSION TABLE
A kilometer it approximately 5/8 of a mil*
a a 4 s
-V-
» to
CUADRO OE CONVERSIONES
Un Kilomctro aauivala a Vg <*• una millai
Ik Kliomtiroa
FIGURE 2-1. LOCATIONS OF MANGROVES, LANDFILLS AND BARREN AREAS NEAR ARECIBO
Source: Torrez-Gonzalez and Gomez-Gomez (1982);
USGS (1982 d); USGS (1982 e).
2-10
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LANDFILL
PIT OR QUARRY
MANGROVE SW AMP \f
OTHER SWAMP
CONVERSION TABLE
A kilometer ie approximately */g of a mile
2 3 4 5
J— k, I —
4 5 10
CUADRO OE CONVERSIONS
Un Kilometro eouivale e V| «*• una mille
10 Millet
I ' J
IS Kilometroe
FIGURE 2-2. LOCATIONS OF MANGROVES, LANDFILLS AND BARREN AREAS NEAR MAYAGUEZ
Source: I orrez-Gonzalez and Gomez-Gomez (1982);
USGS < 1964); IJSGS (1966).
2-11
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however, one potential marsh production site, one and possibly two landfill
sites, and one possible barren area (quarry) site were identified. Prior to
the use of any of these sites as dredged material disposal sites, site-
specific field study would be required.
In addition, site-specific evaluation of dredged material disposal and
monitoring costs would be necessary to determine the economic feasibility of
each potential location as a dredged material disposal site.
2.2.4.3 Land-Based Disposal Options for Ponce
The locations of the mangroves, landfills, and barren areas identified
near Ponce are shown in Figure 2-3. The result of an analysis of the suit-
ability of each site are presented in Appendix C.
The use of land-based disposal alternatives near Ponce may be technically
feasible. One potential diked containment area site for hydraulic fill and
one potential wetlands formation area were identified, no landfills were found
suitable, and four small sand mining pits could be suitable if permanently
inactive. Prior to the use of any of these sites as dredged material disposal
sites, an extensive, site-specific field study would be required.
2.2.4.4 Land-Based Disposal Options for Yabucoa
The locations of the mangroves and landfills found near Yabucoa are pre-
sented in Figure 2-4. No sand or gravel pits or quarries were identified in
this area. The results of the analyses to determine site suitability are
presented in Appendix C.
The use of land-based dredged material disposal alternatives at Yabucoa
may be technically feasible. Sites suitable for hydraulic fill may be avail-
able, although no specific sites for diked containment areas were identified.
There is sufficient land of suitable topography for diked containment areas
near the coast in the Yabucoa Valley. However, this use of these low-lying
coastal locations would compete with the use of undeveloped areas as farmland.
No sites suitable for wetland formation, landfill cover material application,
or barren area cover material application near Yabucoa were identified.
2-12
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LANDFILL
PIT OR QUAKK\
MANGROVE SWAMP
OTHER SWAMP
S-
CONVERSION TABLE
A kilometer it aop'onmaialy V« ot a mil#
Mil* a 0
1 » ) 4 i
10 Mill**
Hilomdtra 1
2 3 4 5 10
13 Kllomairoa
CJAORO OE CONVERSIONS
Un Kiiomairo •qui»«l» a 3/§ d* una milla
FIGURE 2-3. LOCATIONS OF MANGROVES, LANDFILLS AND BARREN AREAS NEAR PONCE
Source: Torres-Gonzalez and Gomez-Ciomez (1982)
DSGS (1982 f); USGS (1982 k>; USGS (1982 h); HSGS (1982 j).
2-13
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LANDFILL
PIT AND QUARRY
~
T
Milaa 0
CONVERSION TABLE
A hilomtltr it appionmauiy &/, of « mil*
1 t J « ft
10 Millet
MANGROVE SWAMP
OTHER SWAMP
M-#
S~#
Kilomalara 0
» i « i io
CUADRO DE CONVERSIONS
Un Kiiomtiro *quival« • dt una milta
1ft Kilomairot
FIGURE 2-4. LOCATIONS OF MANGROVES, LANDFILLS AND BARREN AREAS NEAR YABUCOA
Source: Torrej-Gonzale< and Gomez-Gome/ (1982);
USGS (1982 j); USGS (1982 k).
2-14
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2.2.5 Conclusions Concerning Options for Land Disposal
For Arecibo and Ponce, the small number of potentially usable land-
disposal areas identified indicates that, even if field studies revealed that
sites in those areas were environmentally acceptable as disposal locations,
there would still probably not be sufficient regional capacity to meet the
maintenance dredging needs of the two harbors.
For Mayaguez and Yabucoa, the possibility of finding usable land-disposal
locations cannot be entirely ruled out. Because a number of potentially
serious environmental problems can occur from land disposal in inappropriate
areas, the absence of site-specific field data for the locations in question
means that detailed field studies would be needed before acceptability of any
land-disposal site could be established. However, the general information
that is available regarding land costs in the region suggests that costs may
in fact be prohibitive. For these reasons, it can be concluded that land-
based disposal options are not assured in any harbor region, and that evalua-
tion of ocean-based disposal options is thus warranted for each of the four
harbors .
2.3 SELECTION OF ALTERNATE OCEAN DISPOSAL SITES
Because environmentally acceptable and technically feasible disposal
sites on land were found to be very limited in number and perhaps prohibi-
tively expensive, evaluation of the environmental acceptability of existing
interim ocean disposal sites and alternate ocean sites is warranted. The
methodology used to select the alternate ocean sites, and to evaluate the
interim and alternate ocean sites, is described below.
2.3.1 The EPA/COE Protocol for Ocean Dredged Material Disposal Site (DMDS)
Designation
In 1983, EPA and COE developed a handbook (EPA/COE 1983) recommending a
protocol to be followed in implementing the ocean dumping regulations (ODR)
for designating ocean dredged material disposal sites. This protocol is based
on the "tiered" site-selection screening approach of Pequegnat, et al. (1981).
For technical guidance, the protocol draws from the approach to biological
2-15
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hazard and effects assessment described in a 1983 EPA workshop report on DMDS
evaluation techniques (Reed and Bierman 1983). A brief description of the
phases of EPA/COE's recommended site-designation process follows.
• Phase I: Establish Zones of Siting Feasibility (ZSFs)
- A preliminary screening of environmental factors, based
on the nine evaluation factors specified in MPRSA
Section 102a and the criteria specified in the Ocean
Dumping Regulation (Part 228), to eliminate areas of
known conflict with protected resources and existing
uses of the ocean.
• Phase II: Select Alternate Sites
- Evaluate interim dredged material disposal sites, and
identify other possible ocean disposal sites believed to
be in accordance with the ocean dumping criteria.
• Phase III: Evaluate the Interim and Alternate Sites
- Evaluate the suitability of each of the sites and
select, based on ODR criteria, a site for designation as
the DMDS for continuing use.
2.3.1.1 Criteria for Evaluating Interim Sites and Selecting and Evaluating
Alternate Sites from the Ocean Dumping Regulations
EPA's 1977 Ocean Dumping Regulations establish five general and eleven
specific criteria for evaluating the environmental suitability of ocean dis-
posal sites for dredged materials and other wastes.
Provisions of the general criteria state that:
1) Sites be selected to minimize interference with other activities in
the marine environment.
2) Any elevated pollutants concentrations that occur upon dumping must be
reduced to either ambient or undetectable levels before reaching any
beach, shoreline, marine sanctuary, or geographically limited fishery.
3) The EPA should limit site size so as to localize impacts and facili-
tate monitoring.
4) The EPA should choose sites beyond the "continental shelf" (depths of
200 meters, or approximately 100 fathoms).
2-16
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5) The EPA should select previously used disposal sites whenever pos-
sible .
The eleven specific criteria (40 CFR 228.6) to be considered in addition
to the general criteria described above are as follows:
• Geographical position, depth of water, bottom topography, and distance
from the coast;
• Location in relation to breeding, spawning, nursery, feeding, or pas-
sage areas of living resources in adult or juvenile phases;
• Location in relation to beaches and other amenity areas;
• Types and quantities of wastes proposed to be disposed of and methods
of release, including methods of packing the waste, if any;
• Feasibility of surveillance and monitoring;
• Dispersal, horizontal transport, and vertical mixing characteristics
of the area, including prevailing current direction and velocity, if
any;
• Existence and effects of current and previous discharges and dumping
in the area (including cumulative effects);
• Interference with shipping, fishing, recreation, mineral extraction,
desalination, fish and shellfish culture, areas of special scientific
importance and other legitimate uses of the ocean;
• The existing water quality and ecology of the site as determined by
available data or by trend assessment or baseline surveys;
• Potential for development or recruitment of nuisance species at the
disposal site;
• Existence at or in close proximity to the site of any significant
natural or cultural features of historical importance.
This EIS characterizes each of the study sites with respect to these
criteria.
2.3.1.2 Phase I: Establish Zones of Siting Feasibility
In October of 1983, EPA conducted a preliminary siting feasibility study
(Task 1 report in support of the EIS), in accordance with procedures recom-
mended in the EPA/COE site-designation protocol (EPA/COE 1983). In this
2-17
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approach, the preparers of the assessment develop a series of maps from his-
torical data. The maps deal with important resources (e.g. natural reserves,
nursery areas, corals, historic sites) and use categories (e.g. navigation,
commercial fishing, recreation) addressed in MPRSA 102(a) and the ODR (Section
228). The maps are used in an overlay technique to successively eliminate
sensitive or questionable areas from further analysis. The final composite
map serves to define the zone of siting feasibiliity (ZSF) for the study area.
The ZSF indicates an area free of sensitive resources or incompatible compet-
ing use. The ZSF1s for the Puerto Rican study areas are presented in Figures
2-5, 2-6, 2-7 and 2-8. Factors considered in establishing each ZSF included
information available at the time on physical oceanographic characteristics,
such as surface and deep currents, or degrees of density stratification in the
water columns that would affect the transport of disposed materials from the
point of release to their settling locations. Practical factors set an upper
limit of approximately 15 nmi, or 28 km, on the feasible distance between a
potential ocean DMDS location and the principal dredging location. This limit
is based on estimates that typical speeds of loaded barges operating in a
variety of weather conditions average about 5 knots (nmi/hour), and that the
disposal operation may require one to two hours. Fifteen nmi is thus a
reasonable estimate of the maximum one-way distance that a barge can travel to
complete disposal and return on the same working day. Since numerous environ-
mentally suitable potential DMDS locations were identified within 15 nmi of
each harbor, it was not necessary to consider locations beyond that limit.
2.3.1.3 Phase II-Select Alternate Ocean Disposal Sites
Once the ZSF was determined, EPA staff scientists developed a survey
cruise plan to gather representative data from the interim designated site and
other likely alternate sites. Sites to be considered as alternatives to
interim sites were selected from the previously identified ZSF's, with the
exception of sites in the Ponce study area. Information obtained in intensive
literature searching completed after the Phase I feasibility study provided a
more complete characterization of the physical transport conditions in the
Ponce region. Because of the scarcity of physical oceanographic data avail-
able during the Phase I study, and the consequent lack of assurance that dis-
posal closer to shore would not result in transport into fishing areas east of
2-18
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66°50'
66°40'
66°30*
66°50'
66°40'
66°30*
-------
67°30'
67°10'
18
25'
18
20'
18
15'
18
10'
18
05'
18
00'
100 fm'
18°
25'
18
20'
Nautical Miles
(TTTTTl
T
67°30'
X
67°20'
18
15'
MAVAGUE2
67°10'
18
10'
18
05'
18
00*
FIGURE 2-6. ZONE OF SITING FEASIBILITY FOR MAYAGUEZ
2-20
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-------
66°00'
65°50'
65°401
65 50'
65 40'
-------
Ponce, the nearshore border of the Ponce ZSF had originally been placed about
15 km (8 nrai) offshore. The availability of additional data (Wood et al.
197 5f, and Puerto Rico Department of Public Works 1974, as cited in Chapter 3
of this report) permitted improved estimation of expected transport conditions
in the area. This indicated that disposal in some locations inshore from the
original ZSF would not necessarily result in sediment transport into the sen-
sitive fishing regions to the east. Alternate disposal site considered for
the Ponce area are thus inshore from the original Ponce ZSF.
In March 1984, the EPA oceanographic survey vessel Antelope collected
biological, geological, and chemical data from locations off Arecibo,
Mayaguez, Ponce and Yabucoa. A detailed description of data collections and
analyses is provided under separate cover in the survey cruise data reports
(JRB 1984). Samples were taken at evenly spaced intervals along cruise tracks
that were arranged across the ZSF and approximately parallel to the downward
slope of the bottom topography. Where isobaths (lines connecting locations of
equal depths) were markedly curved (e.g. Mayaguez Bay and off Yabucoa) the
cruise tracks ran at acute angles to one another.
Following preliminary analysis of the survey cruise data, alternate sites
were selected using the following criteria:
• Depth—The Ocean Dumping Regulations general criteria stipulate that
ocean disposal sites must be located beyond the shelf when possible.
This condition could be met in Puerto Rico if sites were about 200
meters (or approximately 100 fathoms) deep, or deeper.
• Seafloor Sediment Composition—Preference was given to sites where the
bottom sediment composition (grain size) was similar to the typical
sediment composition of the material dredged from that harbor.
• Data Availability—If several choices of sites were available that met
the first and second criteria, a site was selected that was centered
around EPA Survey Cruise Sampling Points.
• Monitoring—Preference was given to sites shallow enough to be moni-
tored using equipment typically available to the EPA. This stipula-
tion sets a 925-1,000 meter limitation unless there are special
circumstances requiring deeper disposal sites.
2-23
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• Representative Depths—Where possible within the 1,000-meter limit,
sites should represent the range of depths available in each ZSF.
• Distance from Dredging Site to Disposal Site—If several sites met all
the previous criteria, selections were made that minimized the
distance from the dredging site to the disposal site.
Three alternate sites were selected for detailed evaluation in the
Mayaguez, Ponce and Yabucoa ZSF's. Two sites were selected for Arecibo. A
third site was considered unnecessary because of the uniformity of sea floor
topography and current patterns along the coastline.
Locations and depths of the alternate sites for each harbor are described
in the following sections.
2.4 PROPOSED ACTION FOR ARECIBO
The proposed action for Arecibo is to designate the interim DMDS (Figure
2-9) as the DMDS for continuing use. The characteristics of the dredged
material at this harbor, and the environmental characteristics of the proposed
site and alternate sites considered, are summarized in this section of the
EIS. More detailed descriptions of the environment and expected impacts are
given in Chapters 3 and 4.
2.4.1 Characteristics of the Dredged Material - Arecibo
2.4.1.1 Grain Size of Material
Sediment characteristics from four cores collected in Arecibo Harbor were
analyzed by the COE (Hilton, 1984). The harbor sediments are predominantly
sand. The average specific gravity is 2.53, the average percent moisture is
41.1%, and the average bulk density is 1.91.
2.4.1.2 Existence of Contaminants as Indicated by Elutriate Tests
The elutriate test was developed by EPA and COE to assess the environ-
mental impact of the sediment contaminants. The test was designed to simulate
the physical-chemical processes that occur during dredged material disposal to
2-24
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66°50*
66°401
66°30'
(—(
O
C3
S
KJ
1
VO
SS
H
W
>
f
H
M
SO
H
CO
t-l
i-3
m
u
~n
o
f0
s
n
M
09
o
18
45'
18"
40'
18
35*
18
30'
66°50*
66°40'
66°30'
-------
evaluate the potential release of soluble contaminants. An elutriate test
conducted by Caribtec Laboratories, Inc. (1980a) measured levels of ammonia
(less than 0.3 ug/1), mercury (less than 0.1 ug/1), PCBs (less than 10 ug/i)>
cadmium (less than 0.001 ug/1) and oil and grease (less than 0.001 ug/l) in
four sediment samples collected from Arecibo Harbor. The test values are not
significantly different from ambient concentrations.
2.4.1.3 Existence of Contaminants as Indicated by Bioassay
No bioassay tests have been conducted on sediments taken in or around
Arecibo Harbor. EPA evaluations of need for such testing have indicated that
the sediments do not contain chemical contaminants, and are of a grain-size
compatible with that of the interim DMDS, and thus a need for bioassays is not
indicated under Part 227 of the ODR (Appendix D describes these requirements).
However, in accordance with Part 227, a determination will be made regarding
the need for bioassay testing at the time of each individual permitting
action.
2.4.2 Detailed Consideration of the Alternate Sites
The proposed site and two alternate sites were evaluated according to
site selection criteria listed in Part 228 of the ODR. The alternate sites
were selected to be in accordance with the 5 general ODR criteria (see Section
2.3.1.1 of this EIS). The proposed and the alternate sites were then evalu-
ated under the 11 specific ODR criteria. A summary of the results of these
evaluations is presented in Table 2-4, and described below.
(1) GEOGRAPHIC POSITION, DEPTH OF WATERr BOTTOM TOPOGRAPHY AND DISTANCE FROM
COAST
The proposed DMDS for Af©0'-'50 (the interim DMDS) and the alternate sites
considered are shown in Figure 2-9. Table 2-4 describes the position, bottom
depth, range and average bottom slope of the proposed DMDS and each of the
other sites. Also described are che distance from the nearest coast and the
distance from the harbor entree. The proposed DMDS lies 2.7 km (1.5 nmi)
north of Arecibo, about 1.8 1^ nmi) northwest of Punta Morillos, the
closest point on shore. The has an area of 2.8 km^ (0.9 nmi^), and is
2-26
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TABLE 2-4
COMPARISON OF OCEAN DREDGED MATERIAL
DISPOSAL SITES FOR ARECIBO
COMPARISON FACTOR
EIS
SECTION
INTERIM
SITE
ALTERNATE
SITE 1
ALTEKNATb
SITfc I
Site Characteriseica
• Latitude
e Longitude
• Water Depth (it)
(ft)
t Average bottom
s 1 ope
• Distance from
nearest coast (nmi)
• Distance from harbor (nni)
2.3.2
2.3,2
2.3.2
2.3.2
2.3.2
18° 30' 30" N
66° 43" 16" W
145 - 416 m
474 - 1368 ft
15.42
1.0 N (1.8 km)
1.5 N (2.7 km)
18° 311 34" N
66° 44' 24" W
275 - 537 n
900 - 1770 ft
s ite is off
the shelf
14.9Z
2.5 N (4.5 Ian)
3-5 N (6,5 km)
18° 31* 48" N
66* 46' 00" W
210 - 412 m
690 - 1360 ft
site is off
the shelf
11.5*
2.0 N (4-0 km)
6.0 N (11.0 km)
Site Location Relative to:
• Breeding, spawning,
nursery, feeding or
passage areas
3.1.4.3
1 - 2 nni N
2 - 3 nmi NW
J-4 nmi NW
• Beaches and other
amenity areas
3.1.5
5 -6 nmi NW
6 - 7 nmi NW
8 - 9 nmi NW
Waste. Characteristics
• Types
• Typical Barge Load
• Quantities/Frequency of
Dredging
• Discharge methods
2.4,1.1
1.3.1,
App. B
1.3.1,
App. B
Sand
2000-4000 cy
150,000 cy/3-5 yra
Side or bottom
dumping from
hopper dredges,or
clamshell unloading
f rom scow
Sane as for
Interim Sice
Sane as for
Interim Site
Feasibility of Surveillance
and Moni tor i ng
Feas ible
Feasible
Feasible
Subsurface Transport Characteristics
3.1.1.4
Ve loc i t y ( cej>/ s)
Direction ( True)
Near Bottom Velocity (cra/s)
Direction (True)
Effects of Dredged Material
Disposal in Area
4
2 70°
<5
270
4
2 70°
<•5
27U
4
i 70°
<5
27U
• Previous operations
• Prpupnt operations
L
t
UL
UL
UL
UL
Potential Effects on Human
Uses of the Area
•* Shipping lanes
• Fishing
• • Rec reation
- Beaching
- Diving areas
• Areas of Scientific
- importance
• Mineral Resource's
UL
UL
UL
UL
UL
UL
UL
UL
UL
UL
UL
UL
Potential Effects on
Sit« Ecology
e Marine saisials and
threatened or endangered
' specica
• Critical areas
- Mangroves
- Coral reefs
- Critical wildlife habitats
UL
UL
UL
UL
UL
UL
UL
UL
UL
UL
UL
UL
Potential Effects on
Cultural and Historic
Resources
• Shipwrecks
UL
UL
UL
L • Line!/
P " Possible
UL - Unlikely
2-27
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centered at 18°30'30" N, 66043'16" W. The bottom has an average 15 percent
slope to the north, and is otherwise relatively uniform in topography, Bott
depths range from 145 to 416 meters (474 to 1,368 ft).
Alternate site 1 is located 6.5 km (3.5 nmi) northwest of the harbor
mouth. The site is centered at 18"31'34" N, 66°44'24" W; it has an area of
9 9
2.8 km (0.9 nmi ). Depth at this site ranges from 275 to 537m (900 to
1770 ft).
Alternate site 2 is located 9 km (6 nmi) northwest of the harbor mouth.
2 2 o
The site has an area of 2.8 km (0.9 nmi ) and its center is at 18°3l'48" N}
66"46'00" W. Depth at this site ranges from 210 to 412 m (690 to 1360 ft).
(2) LOCATION IN RELATION TO BREEDING, SPAWNING NURSERY, FEEDING, OR PASSAGE
AREAS OF LIVING RESOURCES IN ADULT OR JUVENILE PHASES
Breeding, spawning, and feeding of fish or shellfish may be assumed to
occur in any coastal marine waters, including those of the proposed DMDS and
the alternate sites. It may also be assumed that many kinds of pelagic (free
swimming) animals such as fish, shrimp, or squid, as well as marine mammals,
seabirds or sea turtles may pass through waters of the sites. There is, how-
ever, no evidence to suggest that the proposed site or any of the alternate
sites have any unique importance to activities of marine animals.
Nursery areas are areas where young organisms are able to find parti-
cularly high concentrations of food and/or shelter and protection from
predators. Typically, nursery areas are associated with semi-enclosed waters
such as estuaries, bays, or mangrove swamps, from which young organisms are
not likely to be transported out to the open sea. Therefore neither the pro-
posed DMDS nor the other sites are likely to serve as nursery areas because
they are all in open-ocean locations well flushed by currents.
2-28
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(3) LOCATION IN RELATION TO BEACHES AND OTHER AMENITY AREAS
The proposed DMDS is about 1.8 km (I nmi) off Punta Morillos, the nearest
shoreline point. It is about 9 to 11 km from the closest recreational beach
area. Alternate sites 1 and 2 are 2 km and 5 km farther from that area. No
dredged material transport into those areas would be expected to occur as a
result of using any of the disposal sites considered.
(4) TYPES AND QUANTITIES OF WASTES PROPOSED TO BE DISPOSED OF, AND PROPOSED
METHODS OF RELEASE, INCLUDING METHODS OF PACKING THE WASTE, IF ANY
Identical types and volumes of dredged material would be released at any
of the alternate sites. The volume of dredged material that will have to be
dredged from Arecibo Harbor annually will vary, depending on rainfall, the
prevalence of storms, high surf, and other environmental factors.
The cumulative amount of material deposited over the full time period of
a dredging and disposal operation is important in evaluating impacts of the
material once it settles to form a deposition mound. Historically, the
harbors have been dredged once every three to five years, with an average
amount of 114,000 cubic meters (150,000 cubic yards) of material being removed
from the harbor during each dredging operation. The short-term effects of
disposal, such as turbidity and increased rates of sedimentation, depend on
the amount of materials released on each trip. Thus, the quantity of disposed
material of concern in evaluating impacts from suspended sediment transport is
2000 to 4000 cubic meters (about 2500 to 5000 cubic yards), the amount con-
tained in a single hopper-dredge or scow load.
(5) FEASIBILITY OF SURVEILLANCE AND MONITORING
Surveillance of dumping operations at the proposed site could be accom-
plished by placing observers aboard disposal vessels or by helicopter observa-
tions. Because the site is close to shore, aerial or ship observations would
not be logistically difficult.
Environmental monitoring of the water column and the benthos at the pro-
posed site should present no problems. Monitoring surveys of the site were
2-29
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successfully conducted by the EPA ocean survey vessel Antelope in 1984. The
site is 3 to 4 km from Arecibo Harbor and has bottom depths of 1^5 to 416
meters. Sampling of the water column thut> presents no problems since the site
is close to Arecibo Harbor in water depths that are easily sample •
(6) DISPERSAL, HORIZONTAL TRANSPORT AND VERTICAL MIXING CHARACTER I ST ICR qg
THE AREA, INCLUDING PREVAILING CURRENT DIRECTION AND VELOCITY IF ANY
The significant difference between the sites is the water column depth
and the bottom profile in the direction of transport relative to the depth to
which the dredged material sinks immediately after disposal (about 350—400 m).
Currents typically flow in a westerly direction along the coastline, at slow
to moderate speeds (3-5 cm/sec). The weak net transport will significantly
influence the mixing and dilution of dredged material discharged at the
interim and the alternate sites. Bottom profiles at all the sites gradually
become shallower (approaching depths of 2)0-300 m) within 2-4 km of the sites.
The interaction of weak, currents with a progressively more shallow sea floor
will result in rapid bottom deposition of the dredged material within short
distances. Concentrations of deposited sediments will therefore tend to be
high within small regions of impact. The disposal of dredged material at
either the proposed site or the alternate sites is therefore expected to
result in containment of the material in a limited area.
(7) EXISTENCE AND EFFECTS OF CURRENT AND PREVIOUS DISCHARGES AND DUMPING IN
THE AREA (INCLUDING CUMULATIVE EFFECTS)
Dredged materials have historically been dumped at the proposed site for
Arecibo. No information has been found to indicate that dumping has occurred
at any of the alternate sites. Analyses of data from benthic sampling at the
proposed site and alternate sites by the 1984 survey cruise indicate that
disposal at the proposed site in the part has resulted in an increased per-
centage of silty sand, as compared to the silt or clayey silt that make up
most of the sea floor at equivalent depths off Arecibo. Benthic organisms
present at the site reflect this changed sediment type, as will be discussed
in point (9) below.
2-30
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(8) INTERFERENCE WITH SHIPPING, FISHING, RECREATION MINERAL EXTRACTION,
DESALINATION, FISH AND SHELLFISH CUL' URE, AREAS OF SPECIAL SCIENTIFIC
IMPORTANCE AND OTHER LEGITIMATE USES OF THE OCEAN
There are no fish or shellfish cult' e operations or desalination near
the proposed site or any of the other coisidered sites. There will be no
interference with shipping lanes because there are no designated shipping
lanes in Puerto Rican waters.
There are some potentially exploitable magnetite sands to the south of
the proposed site, close to the Arecibo Harbor entrance. No exploitation of
these has occurred in the past and there are no known plans to begin mining
these sands. It is not expected that use of the proposed site would result in
transport of dredged material onto these £ lands.
No interference with commercial fish-.ng is expected. There are no exten-
sive fishing operations in the area. The great majority of Puerto Rico's
fishermen fish from 20-foot wooden boats, and winds and waves are particularly
forceful at many times of year on this side of the island, so that fishing
from the small boats is often not possible. A principal form of fishing along
the coast to the east of Arecibo is beach seining, which would not be affected
by disposal operations at the site. No transport of dredged materials to the
beach would be expected from any of the sites considered for this harbor.
Because beaches will not be reached by any sediment released at the
disposal sites there will be no effects on recreational swimming, diving, or
fishing at the shore. There are several natural preserve areas (two protected
mangrove swamps and the Guajataca Cliffs critical habitat area) within the
24 km (15 mile) Arecibo study area, but none would be affected by use of the
proposed site.
(9) THE EXISTING WATER QUALITY AND ECOLOGY OF THE SITE AS DETERMINED BY
AVAILABLE DATA OR BY TREND ASSESSMENT OR BASELINE SURVEYS
Water quality in the general area of this site and the other considered
sites is good, as is typical of well-flushed open water conditions throughout
Puerto Rican coastal areas. The waters are usually optically clear, with
2-3
-------
little suspended material, except for shallow locations closer to shore than
the proposed site. There is no evidence of organic enrichment or eutrophica-
tion. Oxygen concentrations are high and nutrient concentrations are low.
Benthic organisms present at the proposed site reflect the increased sand
content of the site over that of the surrounding area (which presumably
reflects past disposal of Arecibo's sandy dredged materials at this site).
Among polychaete worms, the most abundant organisms present, as well as among
crustaceans, there is a higher percentage of species and individuals present
of ecological types suited to sandy environments than is the case at the
alternate sites or other locations in the ZSF. The fauna at the proposed site
are thus better adapted to survive future disposal operations than are the
fauna at the alternate sites.
(10) POTENTIAL FOR THE DEVELOPMENT OR RECRUITMENT OF NUISANCE SPECIES IN THE
DISPOSAL SITE ~~ "
The proposed site and the alternate sites are in deep ocean waters well
flushed by currents. Nutrients and decaying organic matter in the dredged
materials will therefore not accumulate in sufficient high concentrations to
create eutrophication and resulting blooms of potentially noxious phyto-
plankton. Any human disease organisms that may be present in the dumped
materials are very unlikely to survive and reproduce in the cold, highpressure
environment of the sea floor at the site.
(11) EXISTENCE AT OR IN CLOSE PROXIMITY TO THE SITE OF ANY SIGNIFICANT NATURAL
OR CULTURAL FEATURES OF HISTORICAL IMPORTANCE1
No such features have been identified at the site or in areas that will
be affected by disposal at the site.
2.4.3 Summary: Proposed Site for Arecibo
It is proposed that the existing interim DMDS for Arecibo be designated
as the DMDS for continuing use. The site meets all the criteria of the ODR.
Very little transport of materials away from the proposed DMDS is expected.
Materials released at this site will tend to be deposited on the sea floor,
2-32
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rather than dispersed, because currents are somewhat weak and the sea floor is
not deep enough for prolonged transport of sinking materials to occur. No
adverse effects are expected on living or mineral resources, or socio-economic
and cultural aspects of the environment from the continuing use of this site.
There have been no problems in conducting surveillance and monitoring activ-
ities at this site in the past, and none would be expected in the future.
Benthic sampling indicates that previous use of the site for disposal of
Arecibo's sandy dredged materrials has resulted in an increased percentage of
silt and sand being present at and near the site than is common in the sea
floor off Arecibo. This has apparently had some effect on the bethic ecology
of the site, with a small increase occurring in the numbers of animals adapted
to living in coarser-grained sediments rather than in strictly clay/silt
environments. This indicates that the proposed designation and use of the
interim DMDS as the DMDS for continuing use should result in less of a change
in the ecology of the site than would result from use of any other site in the
zone of siting feasibility.
2.5 PROPOSED ACTION FOR MAYAGUEZ
The proposed action for Mayaguez is to designate alternate site 1 (Figure
2-10) as the DMDS for continuing use. The characteristics of the dredged
material at this harbor, and the environmental characteristics of the proposed
site and the other sites considered, are summarized in this section of the
EIS. More detailed descriptions of the environment and expected impacts are
given in Chapters 3 and 4.
2.5.1 Characteristics of the Dredged Material - Mayaguez
2.5.1.1 Grain Size of the Material
Sediment characteristics from five cores collected in Mayaguez Harbor
were analyzed by COE (Hilton, 1984). The harbor sediments are mixed sand,
silt, and clay. The average specific gravity is 2.53, the average percent
moisture is 53.0 percent, and the average bulk density is 1.72.
2-33
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67°30'
67°201
67°10'
18
25'
18
20'
181"
15*
18
10' |—
18
05'
18
00'
I
Zone of Siting
Feasibillty
> »
100 fm'
Nautical Mllca
rrrm
DDQ Q3_
a
MAYAGUEZ
67°30'
67°20'
67°10'
_ 18
25'
18
20'
18°
15*
18
10'
18
05'
18
00'
FIGURE 2-10. INTERIM AND ALTERNATE SITES FOR MAYAGUEZ
2-34
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2.5.1.2 Existence of Contaminants as Indicated by Elutriate Tests
An elutriate test conducted by Caribtec Laboratories, Inc. (1980b)
measured ammonia (less than 0.3 ug/1), mercury (less than 0.1 ug/1), PCBs
(less than 10 ug/1), cadmium (less than 0.001 ug/1) and oil and grease (less
than 0.001 ug/1) in four sediment samples collected from Mayaguez Harbor. The
test values are not significantly different from ambient concentrations.
2.5.1.3 Existence of Contaminants as Indicated by Bioassays
No bioassay tests have been conducted on sediments taken in or around
Mayaguez Harbor. EPA evaluations of the need for such testing in the past
have indicated that the sediments did not contain chemical contaminants and
were of a grain-size composition compatible with that of the interim site, so
that a need for bioassays was not indicated under Part 227 of the ODR
(Appendix D describes these requirements). However, in accordance with Part
227, a determination will be made regarding the need for bioassay testing at
the time of each individual permitting action.
2.5.2 Detailed Consideration of the Alternate Sites
The proposed site, two other alternate sites, and the interim site were
evaluated according to site selection criteria listed in Part 228 of the ODR.
The three alternate sites were selected in accordance with the 5 general ODR
criteria (see Section 2.3.1.1 of this EIS). Results of the evaluations
according to the specific criteria of the ODR are summarized in Table 2-5 and
described below.
(1) GEOGRAPHIC POSITION, DEPTH OF WATER BOTTOM TOPOGRAPHY AND DISTANCE FROM
COAST
The proposed DMDS for Mayaguez (alternate site 1), the interim site and
the other sites considered are shown in Figure 2-10. Table 2-5 shows the
position, bottom depth range, and average bottom slope of each of the sites.
Also described are the distance from the nearest coast and the distance from
the harbor entrance. The proposed DMDS lies 13 km (7 nmi) northwest of
Mayaguez Harbor, about 8 km (4.5 nmi) from the nearest coast. The site is
2 • 2
centered at 18°15'00" N, 67#15'42" W, and has an area of 2.8 km (0.9 nmi ).
2-35
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TABLE 2-5
COMPARISON OF OCEAN DREDGED MATERIAL
DISPOSAL SITES FOR MAYAGUEZ
COMPARISON FACTOR
EIS
SECTION
INTERIM
KITE
ALTERNATE
SITE 1
ALTERNATE
SITE 2
ALTERNATE
SITE 3
Site Characteristics
• Lat itude
• Long itude
• Water Depth (m)
(ft)
• Average Bottom
s 1 ope
• Distance from
nearest coast (nmi)
• Distance from harbor (nmi)
Site Location Relative to:
• Breeding, spawning,
nursery, feeding
or passage areas
• Beaches and other
amenity areas
Waste Characterise ics
• Types
• Typical Barge Load
• Quantitie«/Frequency of
Dredging
¦ Discharge methods
Feasibility of Surveillance
and monitoring
Subsurface Transport Charactgristics
Velocity (c«/s)
Direction ( True)
Near-bottom velocity (c«/s)
Direction (True)
Potent i a 1 Effects on Hunan
Use9 of the Area
• Sh I pp i ng
• Fishing
• Rec reat ion
- Beaching
- Diving aread
• Areas of Scientific
import ance
• Mineral resources
Potential Effects on
Site Ecology
• Marine man*njls and
threatened or endangered species
• Cr i t ical areas
- Mangroves
- Coral reefs
- Critical wildlife habitats
Potential Effects on
Cultural and Historic
Resource*
• Shipwrecks
2.3.3
2.3.3
2.3.3
2.3.3
2.3.3
3.2.4.3
3.2.3
2.5.1.1
I .3.2,
App. B
1.3.2,
App. B
Feasible
3.2.1-**
18° 15' 00" N
bl° H' 00" W
90 - 300 m
290 - 990 ft
121
2.5 W (4.5 km)
*>.0 W (0 km)
2-3 nmi W
2-3 nmi SW
Sand,slit,clay
2000-4000 cy
69,l(J0-cy/2 yrs
Side or bottom
dumping from
hopper dredges,or
clamshell unloading
from scow
Feasible
!bo°
\lo°
UL
UL
L
UL
UL
UL
L
UL
18 15' 00" N
67° 15* 42" U
350 - 380 m
1150 - 1260 ft
1.7*
3.5 W (6.5 ten)
7.0 W (13 km)
4-5 nmi W
4-5 nmi SW
Same as for
Interla Site
Feasible
iiV
iiV
UL
UL
UL
UL
UL
UL
UL
UL
18 15* 00" N
67° 16' 48" W
420 - 440 m
1380 - 2640 ft
1.4*
4.0 W (7.5 k»)
fl.o w (15 tan)
5-6 nmi W
5-6 nmi SW
Same as for
Interla Site
Feasible
i,V
«v
UL
UL
UL
UL
UL
UL
UL
18 13' 54" H
67° 16' 24" W
325 - 380 m
1070 - 1254 ft
3.1*
5.0 W (9 km)
6.5 W (12 las)
5-6 tml SM
5*6 n«» bw
Same as for
Interla Site
i,V
UL
UL
UL
UL
UL
UL
UL
UL
UL
L ¦ Line ly
P » Poaiiole
UL » Unl ikely
2-36
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The sea floor has an average slope of 1.7 percent to the west, and is other-
wise relatively uniform in topography. Bottom depths range from 350 to 380 m
(1150 to 1260 ft).
The Mayaguez interim site is located 9 km (5 nmi) northwest of the harbor
.2 2
mouth. The site has an area of 0.9 nmi (2.8 km ); it is centered at
18°15;00" N, 67°14'00" W. Depth at this site ranges from 90 to 300 m (290 to
990 ft).
Alternate site 2 is located 15 km (8 nmi) northwest of the harbor mouth.
2.2 o
The site has an area of 2.8 km (0.9 nmi ) and is centered at 18°15'06" N,
67°16'48" W. Depth at this site ranges from 420 to 440 m (1380 to 2640 ft).
Alternate site 3 is located 12 km (6.5 nmi) west-northwest of the
2 2
harbor mouth. The site has an area 2.8 km (0.9 nmi ) and is centered
18°13'54" N, 67°16'24" W. Depth at this site ranges from 325 to
380 m (1070 to 1254 ft).
(2) LOCATION IN RELATION TO BREEDING, SPAWNING NURSERY, FEEDING, OR PASSAGE
AREAS OF LIVING RESOURCES IN ADULT OR JUVENILE PHASES
Breeding, spawning, and feeding of fish or shellfish may be assumed to
occur in any coastal marine waters, including those of the proposed site and
the alternate sites. It may also be assumed that many kinds of pelagic
animals such as fish, shrimp, or squid, as well as marine mammals, seabirds or
sea turtles may pass through waters of the sites. There is however no evi-
dence to suggest that the proposed site or any of the other considered sites
have any unique importance to marine animals. As was the case in the Arecibo
study area (see Section 2.4.2), neither the proposed DMDS for Mayaguez, nor
the other sites considered, are likely to serve as nursery areas, because they
are all in open-ocean locations well-flushed by currents.
There should be no adverse effects on corals or their associated fish
communities from the disposal of dredged materials at the proposed site or the
other alternate sites. Use of the interim site, however, is likely to result
2-37
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in deposition of sediments at levels harmful to corals in the reef areas just
south of the site. Use of any of the alternate sites is expected to result in
sediment plumes that disperse and then settle out before reaching any of the
area's reefs. Use of the interim site, however, will not typically result in
dispersion of the dredged materials in an extended plume. The bottom at this
site is sufficiently shallow that the mass of released materials will land on
the sea floor before reaching the state of dynamic collapse and dissipation.
Consequently, sediment deposition concentrations at or near the site will be
high, well above the value found to cause mortality in some common Puerto
Rican corals.
The location of the sediment mound predicted from the model is actually
between 1 and 2 km (0.5 and 1 nmi) away from the nearest charted coral reef
area (see Section 4.5.2). However, uncertainties about current speed, direc-
tion, and exact point of release mean that the actual mound location could be
displaced by such a distance from the predicted location. Therefore, it is
possible, and in fact likely over a period of years involving numerous dis-
posal operations, that conditions could create unacceptably high levels of
sediment deposition on the reefs adjacent to the interim site.
(3) LOCATION IN RELATION TO BEACHES AND OTHER AMENITY AREAS
There will be no measurable increases in sediment concentrations at any
beaches or shorelines because of dredged material disposal at the interim site
or alternate sites 2 and 3. Sedimentation plumes from disposal at any of the
sites would not be expected to reach the waters of the shoreline anywhere in
this area.
(4) TYPES AND QUANTITIES OF WASTES PROPOSED TO BE DISPOSED OF, AND PROPOSED
METHODS OF RELEASE, INCLUDING METHODS OF PACKING THE WASTE, IF ANY
Identical types and volumes dredged material would be released at any
of the considered sites. The volume of dredged material that will have to be
dredged from Mayaguez Harbor annually will be variable, depending on rainfall,
the prevalence of storms, high 8ur^» and other factors.
2-38
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The cumulative amount of material that is deposited over the full time
period of a dredging and disposal operation is important in evaluating impacts
of material once it settles to form a deposition mound. Historically, the
harbors have been dredged once every 2 years, with an average amount of 53,500
cubic meters (70,000 cubic yards) of material being removed from the harbor
during each dredging operation. The short-term effects of disposal depend on
the amount of materials released on each trip. Thus, the quantity of disposed
material of concern in evaluating impacts from transport of suspended sedi-
ments is 2000 to 4000 cubic meters (about 2500 to 5000 cubic yards), the
amount contained in a single hopper-dredge or scow load.
(5) FEASIBILITY OF SURVEILLANCE AND MONITORING
Surveillance of dumping operations at the proposed site could be accom-
plished by placing observers aboard disposal vessels or by helicopter obser-
vations. Because the site is close to shore, aerial or ship observations
would not be logistically difficult.
Environmental monitoring of the proposed site should present no problems.
Monitoring surveys of the site were successfully conducted by the EPA ocean
survey vessel Antelope in 1984. Benthic monitoring with a box core sampler is
feasible since the depth range of the site is from 350 to 380 meters, less
than the practical limit for box core sampling.
(6) DISPERSAL, HORIZONTAL TRANSPORT AND VERTICAL MIXING CHARACTERISTICS OF
THE AREA, INCLUDING PREVAILING CURRENT DIRECTION AND VELOCITY IF ANY
Depth is the primary difference between the proposed Mayaguez DMDS and
the three alternate sites. With a depth range of 90 to 300 m, the interim
site is considerably shallower than alternate sites, which range from 350 to
400 meters deep as a group. At the shallower interim site, the dredged
material would be deposited on the bottom in higher concentrations over a
smaller area than at the alternate sites. Because of tidal influences, near-
shore currents tend to flow northward on the flood tide and southward at ebb
tide. However, there are eddies and flow reversals in the nearshore area
because of complex bottom topography, tidal forcing, winds and surface runoff.
Offshore currents flow predominantly to the north.
2-39
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(7) EXISTENCE AND EFFECTS OF CURRENT AND PREVIOUS DISCHARGES AND PUMPING TN
THE AREA (INCLUDING CUMULATIVE EFFECTS)
It is not known whether disposal of dredged materials has occurred in the
past at the proposed Mayaguez DMDS or any of the other alternate sites.
Dumping has occurred at approximately 2-year intervals at the interim site.
Analyses of data from benthic sampling at the proposed site and alternate
sites by the 1984 survey cruise did not reveal any effects of previous dis-
posal on the sediment grain sizes and biota of the proposed site.
m INTERFERENCE WITH SHIPPING, FISHING, RECREATION MINERAL EXTRACTION.
nF.SAT.TNATTON. FISH AND SHELLFISH CULTURE, AREAS OF SPECIAL SCIENTIFIC
IMPORTANCE AND OTHER LEGITIMATE USES OF THE OCEAN
There are no fish or shellfish culture operations or desalination near
the proposed site of any of the alternate sites. There will be no interfer-
ence wth shipping lanes because there are no designated shipping lanes in
Puerto Rican waters.
Fish catches in the Mayaguez area are primarily made up of reef fishes
and other species of fish and shellfish that depend on coral reef systems for
food. Reef fishes such as grunts, snappers, and groupers make up a large
percentage of the catch. It is not expected that disposal of dredged
materials at the proposed DMDS would damage coral reefs or their associated
fish or shellfish assemblages. It is possible that disposal at the existing
interim site will damage or even kill corals in the nearshore area south of
the site, as discussed in Section 4.5.2. Such damage to corals in this near-
shore area could perhaps decrease the productivity of local fishery resources.
(9) THE EXISTING WATER QUALITY AND ECOLOGY OF THE SITE AS DETERMINED BY
AVAILABLE DATA OR BY TREND ASSESSMENT OR BASELINE SURVEYS
Water quality in the general area of the proposed DMDS and the alternate
sites is good, as is typical of well-flushed open water conditions throughout
Puerto Rican coastal areas. The waters are usually optically clear, with
little suspended material, except for shallow locations closed to shore than
the proposed site. There is no evidence of organic enrichment of eutrophica-
tion, oxygen concentrations are high and nutrient concentrations are low, as
, , , „ , • frnnical waters such as these,
would be expected in tropin™
2-40
-------
Sediments at all of the sites are primarily silts and clays. Taxonomic
analyses of the fauna collected at the proposed site reveal that the great
majority of the taxa (taxonomic groups) present at all sites are deposit-
feeders, an ecological type well-adapted to living in high-turbidity such as
might be created by dredged material disposal. Other common ecological types
present were carnivores and herbivores, ecological types also able to live in
turbid environments. Analyses of the biological data for other groups indi-
cate that they share the basic ecological characteristics of the majority of
polychaetes in being well adapted to turbidity. It is not likely, therefore,
that continued use of the site will have a detrimental effect on benthic
communities outside of the immediate burial mound.
(10) POTENTIAL FOR THE DEVELOPMENT OR RECRUITMENT OF NUISANCE SPECIES IN THE
DISPOSAL SITE
Because the proposed site, and all considered sites, are in deep ocean
waters well flushed by currents, any nutrients or decaying organic matter in
the deposited dredged materials will not accumulate in sufficient high con-
centrations to create eutrophication and resulting blooms of potentially
noxious phytoplankton. Any human disease organisms that may be present in the
dumped materials are very unlikely to survive and reproduce in the cold, high-
pressure environment of the sea floor at the site.
(11) EXISTENCE AT OR IN CLOSE PROXIMITY TO THE SITE OF ANY SIGNIFICANT NATURAL
OR CULTURAL FEATURES OF HISTORICAL IMPORTANCE
There is one shipwreck in the nearshore area close to the interim site.
Disposal at the proposed site will not affect this feature.
2.5.3 Summary: Proposed Site for Mayaguez
The proposed action for Mayaguez Harbor is the final designation of
alternate site 1 as the dredged material disposal site for continuing use.
The proposed Mayaguez DMDS meets all ODR criteria. It is not proposed that
the formerly used interim DMDS be re-designated for continuing use, because of
the proximity of that site to coral reefs. It is expected that disposal
operations at the interim DMDS will result in exposure of the coral reefs that
2-41
-------
begin 1 to 2 km southeast of the site to increases in sedimentation rates
sufficient to damage living corals and decrease reef productivity* in addi-
tion, the interim site does not meet the general ODR criterion of being off
the shelf: The depth range at the site is 90 to 300 meters (49 to
fathoms), while the limit on the depth of the shelf is conventionally defined
as 200 meters (approximately 100 fathoms).
No adverse effects are expected on living resources such as corals,
fisheries, or nursery grounds from use of the proposed DMDS. It has rio unique
ecological or environmental characteristics, being similar in sediment type
and in its benthic biological community to most other sites in the Mayaguez
study area.
No effects are expected on any mineral resources, or socio—economic and
cultural aspects of the environment from use of the proposed site. There
should be no problems conducting surveillance activities, and the ability to
conduct environmental modeling was demonstrated by the successful sampling
operations of the 1984 OSV Antelope survey cruise.
2.6 PROPOSED ACTION FOR PONCE
The proposed action for Ponce is to designate alternate site 1 (Figure
2-11) as the DMDS for continuing use. The characteristics of the dredged
material at this harbor, and the environmental characteristics of the proposed
site and the other sites considered, are summarized in this section of the
EIS. More detailed descriptions of the environment and expected impacts are
given in Chapters 3 and 4.
2.6.1 Characteristics of the Dredged Material - Ponce
2.6.1.1 Grain Size of the Material
The material to be dredged from Ponce Harbor is predominantly silt (COE
1980c). Results of 17 borings taken from the harbor (COE 1983) indicated that
materials in the northeast corner of the Municipal Bulkhead Turning Baain are
composed of 4 m (14 ft) of fill material underlain by silt through a depth of
2-42
-------
-------
11 m (36 ft) below mean low water. The fill material is soft cement waste and
is considered an inorganic silt. The underlying material is a dark gray, very
soft, somewhat plastic, inorganic silt with small amounts of sand and shell.
In the remainder of the core borings, the material is silt from the surface
through 11 m. The silt is dark gray, very soft, slightly sandy in 8ome areas,
slightly plastic, with a small amount of clay.
2.6.1.2 Existence of Contaminants as Indicated by Elutriate Tests
Chemical analyses were conducted on receiving water from the Ponce
interim disposal site and interstitial water from Ponce Harbor sediment (COE
1983). Test results were compared with Goldberg values (typical sea-water
values). Receiving-water concentrations at the interim disposal site were
found to be similar to Goldberg values except for elevated concentrations of
chromium and lead. Interstitial water had a higher concentration of cadmium,
copper, and zinc than water at the interim DMDS.
2.6.1.3 Existence of Contaminants as Indicated by Bioassay
Bioassays are used during the permit process to determine whether or not
a dredged material is environmentally acceptable for ocean dumping. Bioassay
tests provide a measure of the potential impacts of the dredged material on
the marine ecosystem. ODR requirements are that the liquid phase, suspended
particulate phase and solid phase of the dredged material must be analyzed
separately. The toxicological methods used to evaluate dredged materials are
described in Appendix D.
Bioassay data from a study conducted by Jones, Edmunds, and Associates,
Inc. (1979) on sediments collected from three locations in Ponce Harbor are
presented in Table 2-6. The study concluded that the limiting permissible
concentrations (LPC) based on the liquid phase or suspended particulate phase
bioassays would not be approached during ocean disposal of the three sedi-
ments. The conditions under which this evaluation was made was not specified
in the report. In the solid phase bioassays, none of the three sediments was
toxic to the test organisms. Survival of the polychaetes (Neanthes arenaceo-
dentata) in sediment 2 was significantly different from the control (p"0.05),
2-44
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TABLE 2-6. RESULTS OF BIOASSAYS CONDUCTED ON THREE SEDIMENTS FROM PONCE
HARBOR
Sediment 1 Sediment 2
Sediment 3
•
Liquid phase (;; control survival/--' test survival)
Menidia menidia
30/30
28/24
28/28
F ish
Mvsidopsis bahia
30/26
30/28
30/30
Mysid shrimp
23/20^
Palaeomonetes pugio
28/29
30/29
Grass shrimp
•
Suspended particulate phase (-'/ control survival/-'/ test survival)
Menidia menidia
30/29
30/30
30/30
F ish
Mvsidopsis bahia
30/27
30/27
30/29
Mysid shrimp
Palaeomonetes pugio
28/27
28/24
28/28
Grass shrimp
•
Solid phase (% control survival/% test survival 1
Neanthes arenaceodentata
100/99
100/94(1)
100/98
Folychaete worm
Mercenaria mercenaria
100/100
100/100
100/100
Clam
Palaeomonetes pugio
100/98
100/100
100/98
Grass shrimp
•
Bioaccumulation Potential
-Mercenaria mercenaria
(up,/g)
Control Sediment 1
Sediment 2
Sediment 3
Petroleum hydrocarbons
ND ND
ND
N'D
Mercury
0.027 0.0257
0.0219
0.0332
Cadmium
0.034 0.038
0.052
0.38
Notes: (1) Significantly different from control (p=0.05)
ND-Not detectable: limit of detection - 2 ug/g
Source: Jones, Edmunds and Associates, Inc. 1979
2-45
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but did not differ from control survival by greater than 10 percent and there-
fore, does not exceed the LPC. Bioaccu»ulation teat, conducted with cla».
• ^ nn t-endency to accumulate mercury, cadmium, or
(Mercenaria mercenaria) showed no tenaem-y
petroleum hydrocarbons.
2.6.2 Detailed Consideration of the Alternate Sites
The proposed site, the interim site and two other alternate sites were
evaluated according to site selection criteria listed in Part 228 of the ODR.
The alternate sites were selected to be in accordance with the 5 general ODR
criteria (see Section 2.3.1.1 of this EIS). Results of the evaluations
according to the 11 specific ODR criteria are summarized in Table 2-7, and
described below.
(1) GEOGRAPHIC POSITION. DEPTH OF WATER BOTTOM TOPOGRAPHY AHP^gTAMCE FROM
COAST
The proposed DMDS for Ponce (alternate site 1), the interim site, and the
other sites considered are shown in Figure 2-11. Table 2-7 shows the posi-
tion, bottom depth range and average bottom slope of each of the sites. Also
shown are the distance from the nearest coast and the distance from the harbor
entrance. The proposed DMDS lies 10 km (5.5 nmi) south of Ponce, about 8^km
(4 nmi) from the nearest coast. The site has an area of 2.8 km (0.9 nmi )
and is centered at 17°53'20" N, 66-37'52" W. The bottom has an average 12
percent slope to the south-southwest. Bottom depths range from 330 to 540
meters (181 to 295 fathoms).
The Ponce interim site is located 7.5 km (4 nmi) southwest of the harbor
mouth. The site has an area of 2.8 km2 (0.9 nmi2) and is centered at
17°55'00" N, 66°38'54" W. Depth at this site ranges from 237 to 490 (780 to
1620 feet).
Ponce alternate site 2 is located 12 km (6.5 nmi) south of the harbor
mouth. The site ha, an area of 2.8 km2 (0.9 nmi ); it is centered at
17"52'00" N, 66°38'54" W. Depth at this site ranges from 51 to 700 (1680 to
2310 feet).
2-46
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TABLE 2-7
COMPARISON OF OCEAN DREDGED MATERIAL
DISPOSAL SITES FOR PONCE
COMPARISON FACTOR
CIS
SECTION
INTERIM
SITE
t ALTERNATE
SITE I
ALTEKNAlb
S I ft 2
ALI'EkNhI t
airt >
Site Characteristics
• Latitude
• Longitude
• Water Depth (m)
(ft)
m Average Bottom
8 lope
• Distance from nearest
coast (nmi)
• Distance from harbor (nmi)
2.3 .4
2.3.4
2.3.4
17° 55' 00" N
66° 38' 54" W
237 - 490 m
780 - 1620 ft
17° 53' 20" N
66° 37* 52" U
330 - 540 m
1086 - 1770 ft
17° 52' 00" N
66° 38' 54" W
510 - 700 m
1680 - 2310 ft
17° 52' 04" N
66° 371 42" W
330 - 625 a
1090 - 2060 ft
2.3.4
2.3.4
14.41
3.0 S (5.5k*)
4.0 S (7.5 km)
124
4.0 S (7.5 km)
5.5 S (10 km)
10.8*
6.0 S (11 km)
6.5 S (12 km)
16.87
6.0 S (11 km)
6.5 S (12 km)
Site Location Relative to:
o Breeding, spawning,
nursery, feeding or passage areas
3.3.4. 3
3-4 nmi SE
6 - b nmi SE
6 - J nmi b
g - 7 nmi SE
Waste Characteristics
• Types
+ Typical Barge Load
• Quantities/Frequency of
Dredging
• Discharge methods
2.6.1.1
1.3.3,
App. B
1.3.3,
App. B
Silt
2000-4000 cy
250,000-290,000
cy/3 yrs
Side or bottom
dumping from
hopper dredges.or
clamshell unloading
from scow
Same as for
Interla Sice
Same as for
Interim Site
Same as for
Interlis Site
Feasibility of Surveillance
and Monitor ing
Feasible
Fe a s i b I e
Feasible
Feasible
Sub surface Transport Characteristics
Veloc i t y (eg/s)
Direction ( True)
Near-bottom (cm/s)
Di rec t i on (True)
3.3.1 .4
2V10
Joi-"
>
Potential Effects on Human
Use* of the Area
• Shipping
• Fishing
• R»»c r«»at ion
- Beaching
- Diving aread
• Ar#as of Scientific
importance
• Mineral Resource
11L
til
L
UL
UL
III.
UL
UL
UL
UL
11L
UL
L
UL
UL
UL
UL
I.
UL
UL
Potential Effects on
Site Ecology
• Marine mammals and
threatened or endangered species
• Critical areas
- Mangroves
- Coral reefs
- Critical wildlife habitats
UL
UL
UL
UL
UL
UL
UL
UL
UL
UL
UL
UL
t'L
UL
UL
UL
Potential Effects on
Cultural and Historic
Resources
• Shipwrecks
UL
UL
UL
UL
L ¦ Linely
P ¦ Po » s i d I e
UL • Un l lice ty
2-47
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T is located 11 km (6-5 ™»i) south of the harbor
Ponce alternate site j is locateu
mouth. The site is centered at 17°52'04" N, 66°37'42" W and has an area of
2.8 km2 (0.9 nmi2). Depth at this site ranges from 330 to 625 m (l090 to 2060
feet) .
_n -opFlUNT SPAWNING NURSERY, FEEDING. OR PASSAGE
(2) ^^1^^
A fooHlne of fish or shellfish may be assumed to
Breeding, spawning, and feeding or
including those of the proposed site and
occur in any coastal marine waters, inc
J •. „ TC mav also be assumed that many kinds of pelagic
the other considered sites. It may also
^ nr qmiid. as well as marine mammals, seabirds or
animals such as fish, shrimp, q
~U .wrh uafers of the sites. There is however no evi-
sea turtles may pass through waters or
op,t that the proposed site or any of the other sites have any
dence to suggest that tne f
• rP(>;irds to such activities of marine animals,
special characteristics in regards to
* nnr the other considered sites are likely to
Neither the proposed site nor tne
thev are all in open-ocean locations well
serve as nursery areas, because they ar
flushed by currents.
, . ,-rrn.T to TiFftrHFI AN" OTHER AMENITY AREAS
(3) LOCATION IN RELATION TO BEACHEd
^ nfhpr stretches of shoreline would be affected by the
Several beaches and other stretcne=
i -Aar- t-vnical oceanoeraphic conditions at Ponce,
sediment plumes from disposal under typical ug v
Ponce Harbor. The closest of these is
There are several beach areas west of Ponce
„ , , »«nrn*imatelv 7 km (4 nmi) from the interim site,
beyond Punta Cucharas, approximately
~ ^ i tn 3 km (0.5-1-5 nmi) to the west of Punta
Other beaches are located 1 to 3 km vu.-»
tl;n„ nf che Guanica Commonwealth Forest. Concen-
Verraco, and along the coastline of tne u
jrpas would not be measurably increased as a
trations of sediments m these areas wou
¦ 1 Ji.nnsal at the proposed site. However, it is
result of dredged material disposal at t« v
in chp beach areas off Punta Verraco and Guanica
expected that concentrations m
VI Crossed by disposal operations at any of the
Forest would be measurably in
other sites considered.
2-48
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(4) TYPES AND QUANTITIES OF WASTES PROPOSED TO BE DISPOSED OF, AND PROPOSED
METHODS OF RELEASE, INCLUDING METHODS OF PACKING THE WASTE, IF ANY
Identical types and volumes of dredged material would be released at any
of the alternate sites. The volume of dredged material that will have to be
dredged from Ponce Harbor annually will vary, depending on rainfall, the
prevalence of storms, high surf, and other environmental factors.
The cumulative amount of material deposited over the full time period of
a dredging and disposal operation is important in evaluating impacts of
material if it settles to form a deposition mound. Historically, the harbors
have been dredged once every three years, with an average amount of 190,000 to
220,000 cubic meters (250,000 to 290,000 cubic yards) of material being
removed during each dredging operation. The short-term effects of disposal,
such as turbidity and increased sedimentation rates, depend on the amount of
materials released on each trip. Thus, the quantity of disposed material of
concern in evaluating impacts from suspended sediment transport is 2000 to
4000 cubic meters (about 2500 to 5000 cubic yards), the amount contained in a
single hopperdredge or scow load.
(5) FEASIBILITY OF SURVEILLANCE AND MONITORING
Surveillance of dumping operations at the proposed site could be accom-
plished by placing observers aboard disposal vessels or by helicopter observa-
tions. Because the site is close to shore, aerial or ship observations would
not be logistically difficult.
Environmental monitoring of the water column and the benthos at the pro-
posed site should present no problems. Monitoring surveys of the site were
successfully conducted by the EPA ocean survey vessel Antelope in 1984.
Benthic monitoring with a box core sampler is feasible since the depth of
range at the site is 330 to 540 meters, less than the practical limit for box
core sampling.
2-49
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(6) DISPERSAL, HORIZONTAL TRANSPORT AND VERTICAL MIXING CHARACTERISTICS OF
THE AREA, INCLUDING PREVAILING CURRENT DIRECTION AND VELOCITY IF ANY
At the Ponce sites, depth is not the major determinant of bottom deposi-
tion. The major difference affecting sediment deposition at the sites con-
sidered is related to their distances away from shallow, nearshore shelf
areas. Dredged material released at the interim site has the greatest poten-
tial for bottom deposition on the insular shelf of any of the considered sites
because this flow is expected to carry sediments in significant concentrations
into nearshore areas. Disposal at the proposed site is least likely to result
in transport into nearshore areas.
(7) EXISTENCE AND EFFECTS OF CURRENT AND PREVIOUS DISCHARGES AND DUMPING IN
THE AREA (INCLUDING CUMULATIVE EFFECTS)
No information has been found to indicate that dredged material disposal
has occurred at the proposed Ponce DMDS or any of the other alternate sites.
Dumping has occurred at approximately 3-year intervals at the interim site.
Analyses of data from benthic sampling at the proposed site, interim site and
other alternate sites by the 1984 survey cruise did not reveal any effects of
previous disposal on the sediment grain sizes or the biota of the proposed
site.
(8) INTERFERENCE WITH SHIPPING, FISHING, RECREATION MINERAL EXTRACTION,
DESALINATION, FISH AND SHELLFISH CULTURE, AREAS OF SPECIAL SCIENTIFIC
IMPORTANCE AND OTHER LEGITIMATE USES OF THE OCEAN
There are no fish or shellfish culture operations or desalination near
the proposed site of any of the alternate sites. There will be no interfer-
ence wth shipping lanes because there are no designated shipping lanes in
Puerto Rican waters.
Principal commercial fishing grounds in the Ponce area are on the broad
shelf area to the east. Fishing occurs throughout the shelf area, particu-
larly at coral reefs and near the offshore islands. Specific information was
not found concerning the amount of fishing at the large reefs west of the
Port. If fishing does occur in that area, then the impact of sediments
carried into the area from disposal at Alternate Sites 2 or 3 or the interim
Site would perhaps affect numbers of fish available to fishermen.
2-50
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(9) THE EXISTING WATER QUALITY AND ECOLOGY OF THE SITE AS DETERMINED BY
AVAILABLE DATA OR BY TREND ASSESSMENT OR BASELINE SURVEYS
Water quality in the general area of the proposed Ponce DMDS and at the
alternate sites is good, as is typical of well-flushed open water conditions
throughout Puerto Rican coastal areas. The waters are usually optically
clear, with little suspended material, except for shallow locations closer to
shore than the proposed site. There is no evidence of organic enrichment or
eutrophication; oxygen concentrations are high and nutrient concentrations are
low.
Sediments at all of the sites are primarily silts and clays. Taxonoraic
analyses of benthic organisms collected at the proposed site reveal that the
majority of the taxa (taxonoraic groups) present are deposit-feeders, an eco-
logical type well-adapted to living in high turbidity such as might be created
near the sea floor by dredged material disposal. Other ^common ecological
types were carnivores and herbivores, also able to live in turbid environ-
ments. It is not likely, therefore, that use of the site will have a
detrimental effect on the benthic community outside of any immediate burial
mound that might be formed if immediate deposition, rather than transport and
dispersal, were to occur.
POTENTIAL FOR THE DEVELOPMENT OR RECRUITMENT OF NUISANCE SPECIES IN THE
DISPOSAL SITE ~~~
Because the proposed site, and all considered sites, are in deep ocean
waters well flushed by currents, any nutrients or decaying organic matter in
the dredged materials will not accumulate in sufficiently high concentrations
to create eutrophication and resulting blooms of potentially noxious phyto-
plankton. Any human disease organisms that may be present in the dumped
materials are very unlikely to be able to survive and reproduce in the cold,
high pressure environment of the sea floor at the site.
(11) EXISTENCE AT OR IN CLOSE PROXIMITY TO THE SITE OF ANY SIGNIFICANT NATURAL
OR CULTURAL FEATURES OF HISTORICAL IMPORTANCE
No such features have been identified at the site or in areas that will
be affected by disposal at the site.
2-51
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2-6.3 Summary: Proposed Site for Ponce
The proposed action for Ponce is che final designation of alternate site
1 as the DMDS for continuing use. The proposed Ponce DMDS meets all ODR
criteria. It is not proposed that the formerly used interim DMDS be re-
designated for continuous use, because it is expected that transport of
suspended materials from disposal at that site may result in increased sedi-
mentation rates in beach, coral reef, end preserve areas along the coast west
of Ponce, in violation of general criterion Number 2 of the ODR.
No adverse effects are expected on living resources, including corals,
fisheries, and nursery grounds, from use of the proposed DMDS. It has no
unique ecological or environmental characteristics, being similar in sediment
type and in its benthic biological community to most other sites in the Ponce
study area.
No effects are expected on any mineral resources, or socio-economic and
cultural aspects of the environment from use of the proposed site. There
should be no problems conducting surveillance activities, and the ability to
conduct environmental monitoring was demonstrated by successful sampling
operations during the 1984 OSV Antelope survey cruise.
2,7 PROPOSED ACTION FOR YABUCOA
The proposed action for Yabucoa is to designate Alternate Site 2 (Figure
2-12) as the DMDS for continuing use. The characteristics of the dredged
material at this harbor, and the environmental characteristics of the proposed
site and the other sites considered, are summarized in this section fo the
EIS. More detailed descriptions of the environment and expected impacts are
given in Chapters 3 and 4.
2.7.1 Characteristics of thg Dredged Material - Yabucoa
2.7.1.1 Grain Size of Material
Samples taken from Yabucoa Harbor indicate that the sediment is composed
of silt and sand (COE, 1980d)- The uppermost deposit is reported to consist
of fine silt. Below a depth 14 m (47 ft) the sediment is 3Q£ Band.
2-52
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-------
2.7.1.2 Existence of Contaminants as Indicated by Elutriate Tests
An elutriate test conducted by Laboratorio de Analisis Ambiental, Inc.
(1980) measured mercury (less than 0.1 ug/1), cadmium (less than 10 ug/1), DDT
(less than 1.0 ug/1), and PCBs (less than 1.0 ug/1) in three sediment samples
collected from Yabucoa Harbor. The test values are not significantly dif-
ferent from ambient concentrations. Petroleum hydrocarbon concentrations in
elutriate from Yabucoa Harbor sediments ranged from 10 ug/1-15 ug/1.
2.7.1.3 Existence of Contaminants as Indicated by Bioassays
Bioassay data from a study conducted by Caribtec Laboratories, Inc.
(1980c) on sediments collected from the Yabucoa Harbor Entrance Channel are
presented in Table 2-8. Results of the liquid phase tests indicate that test
organism survival was significantly different (p=0.05) from control survival
in two of the three organisms tested. Results of the suspended particulate
phase tests indicated that test organism survival was significantly different
(p=0.05) from control survival in all three of the organisms tested with LC50
values as low as 12.5 percent. Results from those five bioassays must be
evaluated in terms of initial mixing before a determination of potential
impact from disposal of the dredged materials can be made. Results of the
solid phase bioassays indicated that no environmental impact would be expected
from disposal of that phase. Results of the bioaccumulation studies for
mercury, cadmium, and petroleum hydrocarbons indicated some potential for
uptake. Any such indication is a potential cause for concern. According to
the federal criteria and procedures for bioassay testing, if a greater than 10
percent average mortality occurs in the control organisms, the test data must
be discarded and the experiment repeated (EPA/COE 1977). Therefore, these
bioassay test results have been included in the DEIS for information purposes
only. They would not be acceptable for a permitting action.
The Laboratorio de Analisi9 Ambiental, inc. (1980) conducted two bio-
assays on the liquid phase of sediments from the Sunoil Entrance Channel.
They conducted a gamete fertilization rate bioassay which looks at effects on
the fertilization rate of echinoid gametes (Tripneustes esculentua - white sea
urchin) and a diatom bioassay that measures effects on diatom population
2-5^
-------
TABLE 2-8. RESULTS OF BIOASSAYS CONDUCTED ON THREE SEDIMENTS FROM
YABUCOA HARBOR
Liquid Phase
Suspended Particulate
Phase
Mvsidopsis bahia
(96-hr TL50)
Mvsid shrimp
Skeleconema coscaturn
(96-hr EC50)
Alga
Haemulon flavineatum
LOO?;
70%
(1)
(96-hr TL50)
Fish
Mercenaria mercenaria
Clam
Nereis virens
Polychaete worm
Merita tesselata
Snail
70%(1)
Solid Phase (% Survival)
Control
98%
68%
79%
Bloaccumulation (mg/kg)
Mercury
Cadmium
Mercenaria
mercenaria
Clam
Nereis virens
Polychaete worm
N'erita tesselata
Snail
1.22
2.56
6.0
5.26
4.20
4.33
(1)
0.74
1.9
2.3
0.68
3.4(1)
2.1
13/.
y (1)
, --(I)
l 2.5 ;r
68%(1)
Exposed
99%
75%
77%
Control Exposed Control Exposed
Petroleum Hydrocarbons
Control Exposed
270
ND
ND
NT)
ND
Notes: (1) Significantly different from control (p»0.05)
ND - Not detectable: insufficient tissue weight precluded analysis
Source: Caribtec Laboratories, Inc. 1980
2-55
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growth rates (Skeletonema costatum). Results of the gamete fertilization and
diatom bioassays indicate that there was no toxicity even at an elutriate
concentration of 100 percent. The authors therefore concluded that the liquid
phase of the proposed dredged material would not have any significant adverse
ecological impact on water quality or marine biota.
2.7.2 Detailed Consideration of the Alternate Sites
The proposed site, the existing interim site, and two other Alternate
Sites were evaluated according to site selection criteria listed in Part 228
of the ODR. The Alternate Sites were selected to be in accordance with the 5
general ODR criteria (see Section 2.3.1.1 of this EIS).
The proposed DMDS and the Alternate Site were then evaluated under the 11
specific ODR criteria. Results of these evaluations according to the specific
ODR criteria are summarized in Table 2-9, and described below.
(1) GEOGRAPHIC POSITION, DEPTH OF WATER BOTTOM TOPOGRAPHY AND DISTANCE FROM
COAST
The proposed DMDS for Yabucoa (alternative site 2), the interim site, and
the other sites considered are shown in Figure 2-12. Table 2-9 shows the
position, bottom depth range and average bottom slope of each of the sites.
Also shown are the distance from the nearest coast and the distance from the
harbor entrance. The proposed DMDS lies 11 km (6 nmi) east of Yabucoa Harbor,
about 8 km (4.5 nmi) from the nearest shoreline. The site has an area of 2.8
km^ (0.9 nmi^), and is centered at 18 03 '12" 65°42'18" W. The sea floor
has an average slope of 15 percent to the east. Bottom depths in this site
range from 788 to 1052 meters (431 to 575 fathoms).
The Yabucoa interim site is located 8 kn» (4.5 nmi) east of the Yabucoa
harbor mouth. The site is an irregularly shaped 4-sided polygon with sides
measuring 3.2 km (1.7 nmi), 2.4 km (1-3 nmi)t 3,7 km (2 nmi), and 3.7 km
2 2
(2 nmi); and totalling an area of approxll»ately 3.3 nmi (10 km ). The site
is centered at 18e02'06" N, 65°45'00" W. Depth at this site ranges from 27 to
909 m (90 to 3000 ft).
2-56
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TABLE 2-9
COMPARISON OF OCEAN DREDGED MATERIAL
DISPOSAL SITES FOR YABUCOA
COMPARISON FACTOR
EIS
SECTION
INTERIM
SITE
ALTtKNATE
SUK 1
ALTtKNATE
sire 2
AL 1'tKNAl b
bll't J
Site Characteristics
• Lat i tude
• Longitude
• Water Depth (m)
(ft)
• Average Bottom
s lope
• Distance from nearest
coast (nmi)
• Distance from harbor (nni)
2.3.5
2 . 3.5
2. J. 5
2.3.5
2.3.5
18° 02' 06" N
65° 45' 00" W
27 - 909 m
90 - 3000 ft
1 7.3*
3.5 E (6.5 km)
4.5 E (8 km)
18° or 18" N
*5° 441 48" W
40* - 910 m
1340 - 3000 ft
2tt. U
4.0 E (7.5 km)
5.0 I (9 kn)
18° 03' 12" N
65° 42' 18" U
788 - 1052 m
2586 - 3450 ft
m
4.5 E (8 kn)
fi.O F. <11 km)
18° 03 * 50" N
65° 39' 16" W
732 - 938 oi
2420 - 4000 ft
u. n
5.5 E (10 kin)
8.5 E (IS Vn)
Site Location Relative to:
• Breeding, spawning, nursery,
feeding or passage areas
• Beaches and other
amenity areas
3.4.4.1
3.4.5
none ident i f led
within 15 mile
radius
4-5 ntn \ t
none identified
within 15 mile
radius
4 - 5 nm t
none identit i«d
vi tit in 15 mile
radius
1 - a nmv Nfc
none i4«ntiti«tt
within 15 mile
rdti ius
\\i - U Ht
Waste Characteristics
2.7,1.1
Silty sand
Sane as for
Interlsi Site
Sane as for
Interim Site
Sane as for
Interim Site
• Typical Rarge Load
• Quant it lea/Frequency of
Dredging
• Discharge methods
Feasibility of Surveillance
and Honitoring
1 .i.4,
App. B
1.3.4,
App. B
2000-4000 cy
500,000-600,000/
5-6 yT»
Side or bottom
dumping from
hopper dredges,or
clamshell unloading
from scow
Feas ible
Feasible
Feasible
Feasible
Subsurface Transport Characteristic*
3.4.1 .4
Veloc i t y (c*/*)
Direction ( True)
Near-bottom^velocity (cm/s)
Direction ( True)
15
250°
5-10 Q
225 - 250
250°
5-10 „
225 - 250
25 „
200
5-10 0
225 - 250
£«•
i.\ - 45°
Potential Effects on Human
Uses of the Area
• Shipping
• Fishing
• Recreation
- Beaching
- Diving areas
• Areas of Scientific Importance
• Mineral Resources
UL
L
L
L
UL
*'L
L
L
UL
UL
UL
UL
UL
UL
UL
UL
Ul
UL
UL
UL
Potential Effects on
Site Ecology
• Marine mama Is and threatened
or endangered species
• Critical areas
- Mangrove#
* Coral reefs
- Critical wildlife habitats
UL
UL
L
UL
UL
HL
L
UL
UL
UL
UL
UL
UL
iJL
UL
l'L
Potential Effects on
Cultural and Historic
Resources
• Shipwreck*
P
UL
UL
UL
L • Likely
P " Possible
UL ¦ Unlikely
2-57
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Yabucoa Alternate Site 1 is located 9 km (5 nrai) southeast of the Yabucoa
habor mouth. The site has an area of 2.8 km2 (0.9 nmi ) and is centered at
18°0ri8" N, 65°44'48" W. Depth at this site ranges from 406 to 910 m (1340
to 3000 feet).
Yabucoa Alternate Site 3 is located 15 km (8.5 nmi) east of the Yabucoa
harbor mouth. The site covers an area of 2.8 km (0.9 nmi ) and is centered
at 18°03150" N, 65°39'16" W. Depth at this site ranges from 732 to 938 m
(2420 to 4000 feet).
(2) LOCATION IN RELATION TO BREEDING, SPAWNING NURSERY, FEEDING, OR PASSAGE
AREAS OF LIVING RESOURCES IN ADULT OR JUVENILE PHASES
Breeding, spawning, and feeding of fish or shellfish may be assumed to
occur in any coastal marine waters, including those of the proposed site and
the other considered sites. It may also be assumed that pelagic animals such
as fish, shrimp, or squid, as well as marine mammals, seabirds or sea turtles
may pass through waters of the sites. There is however no evidence to suggest
that the proposed site or any of the Alternate Sites have any unique import-
ance to the activities of marine animals. Neither the proposed site nor the
other sites considered are likely to serve as nursery areas, because they are
all in open-ocean locations well flushed by currents.
The northwest corner of the interim site is over very shallow water; this
is an area characterized by hard bottom, and some corals were found to be
present by the 1984 survey cruise. Disposal at this site would therefore be
likely to result in damage to corals* Disposal at Alternate Site 1 would
perhaps also result in such damage to corals in nearby shelf areas.
(3) LOCATION IN RELATION TO BEACHjjLs _AND OTHER AMENITY AREAS
Several beaches and stretches of shoreline would be reached by the sedi-
ment plumes created by disposal under typical oceanographic conditions at
Yabucoa. Beach areas southwest of Yabucoa Harbor could be affected. The
closest of these is Playa Maunabo, approximately 18 km (10 rani) from the
interim site. Another is located to the southwest off Cabo Mala Pascua. Con-
2-58
-------
centrations from disposal at the interim site or alternate site 1 are expected
to cause unacceptable effects on nearshore water quality. Use of either of
these disposal sites for a typical disposal operation might cause an increase
in ambient sediment levels at the shoreline, which is unacceptable under ODR
criteria.
(4) TYPES AND QUANTITIES OF WASTES PROPOSED TO BE DISPOSED OF, AND PROPOSED
METHODS OF RELEASE, INCLUDING METHODS OF PACKING THE WASTE, IF ANY
Identical types and volumes of dredged material would be released at any
of the alternate sites. The volume of dredged material that will have to be
dredged from Yabucoa Harbor annually will be variable, depending on rainfall,
the prevalence of storms, high surf, and other factors.
The cumulative amount of material deposited over the full time period of
a dredging and disposal operation is important in evaluating impacts of
material if it settles to form a deposition mound. Historically, the harbors
have been dredged once every three to five years, with an average amount of
114,000 cubic meters (150,000 cubic yards) of material being removed from the
harbor during each dredging operation. The short-term effects of disposal
depend on the amount of materials released on each trip. Thus, the quantity
of disposed material of concern in evaluating impacts from transport of
suspended sediments is 2000 to 4000 cubic meters (about 2500 to 5000 cubic
yards), the amount contained in a single hopper-dredge or scow load.
(5) FEASIBILITY OF SURVEILLANCE AND MONITORING
The proposed site is characterized by deep water with depths ranging from
788 to 1052 meters (2600 to 3450 feet). Transit distances to the site are not
so large as to prevent surveillance. The sea floor is deep, which may present
some problems for monitoring activities. However, monitoring of the pre-
viously used interim DMDS also has presented problems in the past. In areas
closer to shore than the proposed site, including at the interim site, hard
bottom was struck by the box-core sampler, which was damaged, and there were
difficulties in achieving successful coring operations in other shallow por-
tions of the ZSF. Because of the very steep escarpment that forms the shelf
2-59
-------
edge throughout the Yabucoa area, all off-shelf sites in the area will contain
deep-water locations. Sampling was successfully accomplished at the center of
the proposed site on the 1984 cruise, because sufficient cable has been
installed on the OSV Antelope to permit deep-water box core deployment.
(6) DISPERSAL, HORIZONTAL TRANSPORT AND VERTICAL MIXING CHARACTERISTICS OF
THE AREA, INCLUDING PREVAILING CURRENT DIRECTION AND VELOCITY IF ANY
The principal difference between the interim site and the three alternate
sites is their depth ranges. The interim site is located over the shelf-break
with the northwest corner of the site in shallow water (20-40 m) and the
southeast corner of the site over the continental slope in water as deep as
900 m. In contrast to the alternate sites where depths are no less than 400
m, at the interim site significantly higher concentrations of dredged material
would be deposited on the bottom, because of the shallowness of portions of
the site. Disposal operations at the three alternate sites would tend to
result in southwesterly offshore transport over deep water with dispersion of
the dredged material to negligible concentrations in the water column and on
the bottom.
Current measurement data are available from numerous previous studies to
characterize surface and subsurface transport patterns over the deep ocean off
Yabucoa. Subsurface currents are strongly influenced by the complex bottom
topography of the region with rapid flow along the steep escarpment over the
slope. Subsurface flow is characterized by eddies on the order of 20 km wide,
extending to depths of 400 m. Disposal of dredged material at alternate site
2 and to a lesser extent at alternate site 3 would tend to result in rapid
dispersion of the waste plume over a long distance over deep water. Expected
environmental concentrations of suspended sediments from dredged material
disposal at those sites would be negligible.
(7) AND EFFECTS OF CUR^ PREVIOUS DISCHARGES AND DUMPING IN
THE"AREA (INCLUDING CUWULAii.vE EFFECTS)
No information has been found to indicate that disposal has occurred at
the proposed site or either of the other alternate sites. Data on sediment
types from benthic sampling at the proposed site, the interim site, and
2-60
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alternate sites by the 1984 survey cruise did not reveal any effects of pre-
vious discharges at the interim site; where soft-bottom was found, sediments
were similar in composition to those throughout the Yabucoa study area.
(8) INTERFERENCE WITH SHIPPING, FISHING, RECREATION MINERAL EXTRACTION,
DESALINATION, FISH AND SHELLFISH CULTURE, AREAS OF SPECIAL SCIENTIFIC
IMPORTANCE AND OTHER LEGITIMATE USES OF THE OCEAN
There are no fish or shellfish culture operations or desalination near
the proposed site of any of the alternate sites. There will be no interfer-
ence with shipping lanes because there are no designated shipping lanes in
Puerto Rican waters.
A principal fishing area of the Yabucoa region is the very narrow shelf
south of Cabo Malo Pascua. Because of the very deep waters in this region,
suitable shallow fishing areas are very limited and fishermen concentrate
their efforts along this coastline. Use of alternate site 1 or the interim
site would be expected to result in transport of some dredged materials into
this area. It is possible that such increased turbidity would decrease
availability of fish to fishermen by causing periodic movement out of the
area.
(9) THE EXISTING WATER QUALITY AND ECOLOGY OF THE SITE AS DETERMINED BY
AVAILABLE DATA OR BY TREND ASSESSMENT OR BASELINE SURVEYS
Water quality in the general area of this site and the alternate sites is
good, as is typical of well-flushed open water conditions throughout Puerto
Rican coastal areas. The waters are usually optically clear, with little
suspended material, except for shallow locations closed to shore than the
proposed site. There is no evidence of organic enrichment of eutrophication,
oxygen concentrations are high and nutrient concentrations are low.
Sediments in soft-bottom sites of the Yabucoa ZSF are primarily silts and
clays. Taxonomic analyses of the fauna collected at the proposed disposal
site and other locations throughout the ZSF reveal that the majority of the
taxa (taxonomic groups) present at all sites are deposit feeders, an eco-
logical type well-adapted to living in high-turbidity environments. Other
2-61
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common ecological types were carnivores and herbivores, also able to live in
turbid areas. It is not likely, therefore, that use of the proposed DrtDS will
have a detrimental effect on soft-bottom benthic communities of the area.
(10) POTENTIAL FOR THE DEVELOPMENT OR RECRUITMENT OF NUISANCE SPECIES IN THE
DISPOSAL SITE
Because the proposed site, and all considered sites, are in deep ocean
waters well flushed by currents, any nutrients or decaying organic matter in
the dumped dredged materials will not accumulate in sufficient high concen-
trations to create eutrophication and resulting blooms of potentially noxious
phytoplankton. Any human disease organisms that may be present in the dumped
materials are unlikely to be able to survive and reproduce in the cold, high
pressure environment of the sea floor at the site.
(11) EXISTENCE AT OR IN CLOSE PROXIMITY TO THE SITE OF ANY SIGNIFICANT NATURAL
OR~CULTURAL FEATURES OF HISTORICAL IMPORTANCE"
One shipwreck has been identified, near alternate site 1 and the interim
site. Use of the proposed site will have no effect on thi9 feature.
2.7.3 Summary: Proposed Site for Yabucoa
The proposed action for Yabucoa Harbor is the final designation of alter-
nate site 2 as the DMDS for continuing use. This site meets all ODR criteria.
It cannot be recommended that the interim DMDS or alternate site 1 be desig-
nated as the DMDS for continuing use. The interim DMDS includes a very
shallow, shelf area, and thus does not meet the second general criterion of
the ODR (see page 2-17). Live corals have been identified within the interim
site and adjacent to alternate site 1. Finally, transport modeling indicates
that disposal at either of these two sites is likely to result in transport of
suspended sediments into the shoreline areas to the southwest, where the very
narrow shelf is an important fishing area.
No adverse effects are expected on living resources, including corals,
fisheries, and nursery grounds, from use of the proposed DMDS. It has no
unique ecological or environmental characteristics, being similar in sediment
2-62
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type and in its benthic biological community to most other locations of the
similar depth in the Ponce study area.
No effects are expected on any mineral resources, or socio-economic and
cultural aspects of the environment from use of the proposed site. There
should be no problems conducting surveillance activities, and the ability to
conduct environmental monitoring was demonstrated by successful sampling
operations at this site during the 1984 OSV Antelope survey cruise.
2-63
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3. CHARACTERISTICS OP AFFECTED ENVIRONMENTS
-------
3. CHARACTERISTICS OF AFFECTED ENVIRONMENTS
3.0 INTRODUCTION
This chapter describes the natural and man-made (socioeconomic) environ-
ments of the four study areas (Arecibo, Mayaguez, Ponce and Yabucoa). These
descriptions include only those elements of the environments that may be
affected by use of the interim dredged material disposal site, or any of the
alternate sites being evaluated in the EIS.
The different elements of the environments are described with differing
levels of detail, depending on their relative importance to the selection of a
recommended site for each harbor. Thus, benthic biology, coral reef ecology,
and the effects of ocean currents on sediment transport and dispersal are dis-
cussed in more detail than other components of the ecosystem.
Section 3.0 discusses aspects of protected resources that are applicable
to all four harbor areas. Sections 3.1, 3.2, 3.3 and 3.4 present information
specific to Arecibo, Mayaguez, Ponce and Yabucoa respectively.
3.0.1 Soft-Bottom Benthic Communities
This section discusses certain general characteristics of benthic
organisms that affect their sensitivity to turbidity or burial by dredged
material disposal. These characteristics apply equally to benthic communities
in the zones of siting feasibility (ZSF's) at each harbor. Specific charac-
teristics of the benthic biota of the ZSF's will be described in Sections
3.1.4, 3.2.4, 3.3.4, and 3.4.4, for Arecibo, Mayaguez, Ponce and Yabucoa, res-
pectively.
Animals that inhabit similar sediment types (i.e., sediments with similar
mixes of particle sizes, ranging from muds to coarse sands) will be similar in
their susceptibility to harm from increased turbidity or burial under
deposited sediments. There is a close relationship between habitat grain size
and the sensitivity of organisms to dredged material impacts. Based on this
relationship, sediment and biological data collected from the four ZSF's by
the EPA 1984 Survey Cruise, and biological data from historical sources can be
3-1
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used to determine the principal feeding strategies and other ecological char-
acteristics in the soft—bottom benthic communities within sediment-transport
distance of interim and alternate disposal sites. The information can be used
to predict dredged material impacts on benthic organisms following release at
potential disposal sites.
Areas with f ine-graitied sediments (muds and fine silts) will typically
have relatively high turbidity levels, especially near the sea floor, and
therefore tend to be colonized by turbidity-resistant benthic organisms,
whereas other types will be eliminated. Suspension-feeders, animals that trap
food particles from water passed through filtering mechanisms of various
kinds, are often not able to survive in turbid water because their feeding
organs become blocked or clogged by accumulations of fine sediment particles.
Examples of suspension feeders common in most nearshore waters are some
bivalve molluscs (such as many clams, oysters and scallops) and members of
groups of polychaete worms, such as the families Sabellidae, Serpulidae, or
Chaetopteridae, that use particularly delicate filtering structures to trap
food. The deposition of fine-grained dredged materials (muds or even fine
silts) in the habitats of such organisms will either impair or destroy their
feeding capabilities, and may in some cases destroy respiratory organs as
wel 1.
In contrast, deposit feeders, typically burrowing animals that either
ingest materials buried in sediments, or ingest the sediments themselves and
absorb attached organic matter, will be affected very little by increases in
turbidity. Deposit feeders include a large variety of animals, such as worms
of many kinds representing over a dozen major taxonomic groups, tiny burrowing
crustaceans, some bivalves, and certain snails. Such animals will typically
not be harmed by inputs of suspended mud or fine silts to their areas. How-
ever, the deposition of sand or coarse silts can have a devastating effect on
deposit feeders. Many of these burrowing animals may be unable to move
properly through, or will be abraded by, coarse or mixed sediments, or will be
abraded by or unable to survive ingestion of coarse sand particles.
Because deposition of sediments unlike those already present in an area
may damage or kill many of the resident benthic invertebrates, and then pre-
3-2
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vent recolonization by animals of the same or similar kinds, EPA and COE have
recommended that dredged materials be disposed of in areas with similar sedi-
ment characteristics to the materials being dumped. Thus, an important factor
considered in the selection and evaluation of potential dredged material dis-
posal sites (DMDSs) is how well the sediment type and associated biological
community at and surrounding each potential site match the characteristics of
sediments most likely to be dredged from the principal harbor(s) of the region
served by that site.
Characterizations of sediments from each harbor are given in Section 2.4.
Descriptions of the biota and sediment types present in the areas of proposed
disposal sites for each of the four harbors are given in Sections 3.1.4,
3.2.4, 3.3.4, and 3.4.4.
3.0.2. Ecological Characteristics of Puerto Rican Corals and Associated Fish
Communities
Features common to coral reefs throughout the harbor areas considered in
this EIS are summarized in this section. Locations of corals at or near pro-
posed disposal sites for each harbor are discussed in Chapter 4 and shown in
Figures 4-1 through 4-8. Coral reefs are exceptionally productive marine
habitats second only to certain seagrass flats in the production of organic
materials by living organisms (Levinton 1982). Because of the relatively low
productivity of surrounding tropical seas, coral reefs in all areas of the
world are important in their ability to trap and rapidly recycle available
nutrients to their associated plant and animal communities. The highly pro-
ductive nature of Puerto Rican coral reefs has been confirmed by Odum,
Burkholder and Rivero (1959) and Glynn (1964). Puerto Rican coral reefs also
play an important role in supporting the island's small-scale (artisanal)
fisheries.
Coral reefs are common along all coasts of Puerto Rico with the exception
of the north coast, where they are generally absent. They are present along
the coastlines at or adjacent to the dredged material disposal sites for
Mayaguez, Ponce and Yabucoa. The absence of coral reefs on the north coast,
where Arecibo is located, has been attributed to the influx of waters from the
3-3
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four largest Puerto Rican rivers (the Arecibo, Manati, Plata and I^iza), which
empty into the sea off the north coast. The influence of these rivers results
in reduced salinities and high turbidities, both of which are unfavorable to
the growth of corals. Normally heavy seas that constantly resuspend sediments
a factor in creating turbidity that prevents
along this coast may also be a tacior j.u j y
successful coral colonization (Glynn 1973).
Reefs characteristic of the Puerto Rican coast include fringing-reef
communities of shallow areas, dominated by the coral Porites furcata.
Dominant species inhabiting Porites, communities include the mantis shrimp,
Gonodactylus oerstedii; the green crab, Mithrax scul£tus; the crab, Petro^
listhes galathinus; the echinoid, Echingmetra lucunter; the sea cucumber,
Holothuria parvula; and the brittle star, Ophiothrix anfiulata. Young spiny
lobsters (Panulirus argus) are often found in Porites furcata reefs (Glynn
1964). In addition to fringing reefs, all three coasts also have deeper off-
shore bank reefs. A prominent coral of Puerto Rican offshore reefs is the
golden brown elkhorn coral Acropora, ^almata ¦ Elkhorn coral contains numerous
indentations and holes, which provide refuges for large numbers of spiny
lobsters of all sizes.
e f^ohormen in Puerto Rico are individual small-boat
The great majority of tisnerme" m
11 aDDroximately 6 million pounds per year of
operators, who collectively land appi"* r «-
. , . ,ic- u u „f „hi ch is harvested from coral reef environments
finfish and shellfish, much ot whic»
p ,-iture 197 5, 1980, 1981). The catches are in
(Puerto Rico Department of AgricuL
i f fishes and other species that live near reefs and
large part composed of reet tisnes
depend on coral re.f systems for food (P.rri.h and Zimernan 1977) and pro-
tection (Baku. 1966). ReeJ-associated ff*" such as grunt., .n.pper. and
u - norppnt of the catch Qf Puerto Rico's fishermen
groupers make up about 51 percent
/ , jr. o u « iQftfi) Not only re®f-related species derive
(Weiler and Suarez-Caabro 19BU,). r
, community' er*thic invertebrates and fishes of
nourishment from the coral reet co»
„ L „ J. so well' Betithic invertebrates of these sand
adjacent soft-bottom areas do so
fiiibstantial energy from reef-derived detritus
or mud environments receive suds
. , e^als) They p*38 this energy through the food chain
(particulate organic materials;.
i • a f Homersal fishes °m-feeding) that typically feed
to the various kinds of detnersai * t> jv
_ as well as C e reef-associated fishes that
on sand and mud communities, as w
n r aae> nn neiahboring flat8 tl8h and Zimmerman 1977).
occasionally forage on neig»"
3-4
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Adult reef fishes often migrate to the shelf edge or non-reef areas to
spawn; possibly because this increases the chance of keeping the eggs and
young larvae out of the reach of reef predators (Colin 1982). Recruitment
(the metamorphosis and settling of juvenile aquatic animals into their adult
habitats) may follow a strictly planktonic larval existence, or may be pre-
ceded by intermediate periods spent in shallow, nearshore habitats.
The following section discusses the importance of one kind of nearshore
environment that shelters the young of some species of reef fishes as well as
other open-water fishes.
3.0.3 Mangroves: Special Breeding and Nursery Areas
Recruitment and settling of juvenile fish and shellfish into their adult
habitats often follows a larval and early juvenile period spent in protected
nearshore environments. In Puerto Rico, as in many other tropical coastal
areas, mangroves are particularly important in serving this purpose. Mangrove
swamps and estuaries are the feeding areas for the juveniles of such commer-
cially valuable Puerto Rican fish as the yellow fin mojarra and many snapper
(lutjanid) and grunt (pomadasyid) species (Austin and Austin 1971; Ogden
1982). Interdependences between the fishery-supporting coral reefs and
nearby coastal mangroves make it important to evaluate the potential for
impact8 from dredged material disposal on both habitats.
In Puerto Rico, and the tropics in general, mangrove forests consist of a
series of zones, each characterized by a predominant species of tree. Forests
bordering quiet, open water at elevations that may be flooded by spring tides
are composed primarily of the red mangrove, Rhizophora mangle, while the next
zone towards higher ground is dominated by the black mangrove, Avicennia
tomentosa. Mangroves send breathing roots upwards for a meter or more from
the mud surface. A diverse and particularly productive community of marine
organisms inhabits the submerged root and sediment ecosystem of the primarily
black-mangrove swamps of protected shorelines. Characteristic shellfish and
other benthic animals of Puerto Rican mangrove communities include the edible
oyster, Crassostrea rizophorae; the crab, Aratus pisonii; the shrimp, Stenopus
hispidus; the spotted sea cucumber, Stichopus badionotus; the tunicate,
3-5
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Ascidia nigra; the marine snail, Littorina angulifera; the sea anemone,
Bartholomea annulata; and the large polychaete worm, Sabellastarte magnifica.
There are also highly productive phytoplankton and zooplankton assemblages,
supported by the rapid input of nutrients from land run-off and the recycling
of decaying plant litter and other mangrove and algal debris.
The variable salinity and temperatures of the shallow waters of mangrove
swamps and mangrove-lined estuaries, together with their limited depth and
spatial extent, make them unsuitable as permanent habitats for adult fish of
most species. But the abundance of small-scale refuge areas, and the rich
concentrations of food organisms and high organic-content detritus, make them
particularly good habitats for larval and juvenile stages of many species of
fish and shrimp. Mangrove systems thus ultimately provide energy to open-
water marine food chains through the emigration of young fish and shrimp that
achieved their early growth by feeding on the high densities of prey organisms
in the mangrove communities. Information on the species of fish in Puerto
Rico that use mangrove nursery grounds and would potentially be affected by
use of the various dredged material disposal sites under consideration is
presented in the following section, and later for each harbor area.
3.0.4 Fisheries
The entire Puerto Rican shelf out to bottom depths of 0 to 40 fathoms
(0-72 meters), also referred to as the "platform", is heavily used by commer-
cial and recreational fishermen, especially on the east, south and west areas
of the island (Caribbean Fishery Management Council 1984). As of 1982,
CODREMAR (an abbreviated acronym for the Corporation for Development of
Fluvial, Lacustrine and Marine Resources of the Puerto Rico Department of
Natural Resources) reported a total of 1,872 fishing boats under operation in
Puerto Rico (Caribbean Fishery Management Council 1984). The majority of the
boats are small, one-man wooden boats with limited ranges (O'Connor 1983).
Exploited fishes are thus mainly reef fishes, which are the most concentrated
and abundant fishes in the neaf^ore area8 accessible to these artisanal
(small-boat) fishermen. Commercially important reef fishes throughout the
island include groupers, mojarr«. Porgies, snappers and grunts. Fishes from
^nntituted 51 percent of the 1978 Puerto Rico landings
these three groups const it"
^..hra 1980, as Clted ^ O'Connor 1983).
3-6
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Total landings in Puerto Rico were 4.7 x 10 lbs. for the period from
October 1982 to July 1983 (Caribbean Fishery Management Council 1984).
Highest landings were off the west coast (2.3 x 10^ lbs.), followed by those
for the south coast (1.2 x 10 ) and the east coast (8 x 10 ). Fishing is
least productive on the north coast (5 x 10"*), in part because of the high
seas that generally limit small boat operations, but also because of the
limited number of coral reefs (see Section 3.0.2).
3.1 CHARACTERIZATION OF THE AFFECTED ENVIRONMENT FOR ARECIB0
3.1.1 Oceanographic and Climatological Characteristics, Arecibo
3.1.1.1 Bathymetry
The shelf (the sea floor out to depths of 200 meters) is a fairly con-
stant 2 to 3 kilometers wide along the north coast of Puerto Rico near Arecibo
(Figure 3-1 and 1-1). The width of the slope from 180-meter (100-fathom)
depths to 900-meter (500-fathom) depths is more variable. The slope is nar-
rowest (7 kilometers) directly north of Arecibo Harbor. West of the harbor,
the 900-meter (500-fathom) depth is reached about 12 kilometers offshore.
East of the harbor, it is reached at about 9 kilometers. The bottom has a 6°
gradient to the north at the interim and alternate sites.
3.1.1.2 Climatology
The climate of Arecibo is dominated by the easterly trade winds. Data
gathered in Barceloneta, about 16 km (10 miles) west of Arecibo, from July-
December 1974, show an average wind velocity of 4.2 m/s, with an average
maximum velocity of 6.7 m/s between 1230 and 1530 hours and an average minimum
velocity of 3.1 m/s between 0630 and 0930 hours (Black & Veatch 1975). The
surface of the nearshore ocean near Arecibo is choppy from mid-day to 1600
hours; otherwise, the surface is generally calm. Sea waves commonly run three
meters in height and may reach seven meters or greater several times a year
(Black and Veatch 1975).
3-7
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0
100
—r
-
200
¦ !
-
300
• % j
-
400
¦ ;r% |
ARECIBO:
¦
500
Rio Grande
1 (~) .
I
Alternate Site
600
'~v"
m
700
800
5 10
15 20
2
Distance
(km)
FIGURE 3-1. BATHYMETRIC PROFILE OFFSHORE FROM ARECIBO, RIO
GRANDE TO ALTERNATE SITE 1
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3.1.1.3 Hydrography
Figure 3-2 shows temperature data gathered from six deep-water sampling
stations at Punta Manati, approximately 21 km east of Arecibo (Wood et al.
1975b). The maximum seasonal difference in surface water temperatures was
2.6°C, and little seasonal temperature change occurred below 250 meter depths.
A deeper thermocline (the depth of the sharpest temperature change between
surface and deeper waters) occurred in winter and spring than in summer and
fall.
The salinity data from the same study (Figure 3-3) reveal an increase in
salinity from the surface to about 150 m, with a slight decrease at greater
depths. The highest surface salinity occurs in the spring, due to dry-season
evaporation; wet-season dilution causes minimum surface salinity in the fall.
Salinity at 50-100 m reaches a minimum in the winter, when low salinity sur-
face water is mixed down by storms. It increases steadily throughout the rest
of the year.
The density profiles resulting from these temperature and salinity values
for the Punta Manati area are shown in Figure 3-4. The winter and spring pro-
files show a shallower pycnocline (the depth of the greatest density gradient)
than in summer and fall. In winter and spring, pycnocline depths are about
125 m with an average density gradient of 9 x 10 ^/m. In comparison, summer
and fall are characterized by a pycnocline depth of 60-80 meters and an
average density gradient of 2 x 10 ^/m. These depths will affect the depth to
which released dredged materials will sink in the initial, rapid descent
phase, and therefore affect the amount of time sediments will spend in the
water before settling out. This information is used in the sediment transport
model used to predict ultimate transport distances and deposition concentra-
tions (Section 4-1).
3.1.1.4 Circulation
Surface currents on the north shore of Puerto Rico generally travel
parallel to the shore from east to west, with a small net drift to the west.
Deeper currents tend to travel opposite to the surface currents. As shown in
Figure 3-5, measurements at the Isolte site (Puerto Rico Nuclear Center 1975),
3-9
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TEMPERATURE *C
16 18 20 22 24 26 28
FIGURE 3-2. AVERAGED SEASONAL TEMPERATURE PROFILE OFF PUNTA
MANATI, 1973 AND 1974
Source: Wood et al. 1975b.
3-10
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SALINITY %o
34 35 36 37
FIGURE 3-3. AVERAGED SEASONAL SALINITY PROFILES OFF PUNTA
MANATI, 1973 AND 1974
Source: Wood et al. 1975b.
3-11
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0
100
D
E
P
T
H
m
200
300
FIGURE 3-4. AVERAGED WATER DENSITY PROFILES, BY SEASON, OFF
PUNTA MANATI, 1973 AND 1974
Source: Wood et al. 1975b.
DENSITY Ot
20 22 24 26 28
_l I L2 LI 1 I I I I J
1
1 1 »
PMA
Winter 1
Spring 2
f
Summer 3
Fall 4
I
• 1 <
1— i_ .
3-12
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u>
I
66*50' 66*40' 66*30'
i i i
J
SURFACE LAYER TRANSPORT (cm/s)
I (DEPTHS OF OBSERVATION IN METERS)
18*45"
I » * ®
E = EBB TIDE F - FLOW TIDE
® PUERTO RICO DPW (1974) 7/71, 10/71
18*45'
ir4»'
(2) BLACK « VEATCH (1975) 10-11/74
(3) PUERTO RICO NUCLEAR CENTER (1975) PRNC-182, 10/72
© PUERTO RICO NUCLEAR CENTER (1975) PRNC-197, 1-2/74
© O'CONNOR (1903)
18*40'
11*35'
-
18*35'
irar
^ 340
.-'•Of— ~~\
^ t J , ^£5 jui v^^- » ^ j17"*
• ^
ARKC1BO
18*30'
NAUTICAL MILES
l 1 1 1 1 1
0 1 2 3 4 5
1 I 1
66*50' 66*40' 66*30'
FICURE 3-5. SURFACE LAYER TRANSPORT, ARECIB0 STUDY AREA
-------
/\i nA at. _i iQ7 5b) and at Barceloneta (Black and
the Punta Manati site (Wood et al. iv/io),
Veatch 1975) all show maximum velocities of about 30 cm/sec. The maximum
velocities are westward during ebb flow and eastward during flood flow. The
literature indicates that net drift velocities average 3-5 cm/sec. The study
at the Isolte site found that the net drift direction seemed to have a
seasonal pattern, with eastward net drift during the summer and westward net
drift during the winter. Onshore net drift was observed in October 1971 at
Arecibo (Puerto Rico DPW 1974), while Black and Veatch found a net offshore
drift at Barceloneta in October-November 1974. The Isolte study also showed
deep-water currents (Figure 3-6) that resulted in a subsurface net drift to
the east, while the surface net drift was to the west.
3.1.2 Geologic and Geochemical Characteristics, Arecibo
The interim and alternate sites at Arecibo have similar bottom types and
sediment characteristics. The following sections describe the surficial
geology, the bottom types, grain size distributions, and geochemical charac-
teristics at each of the sites.
3.1.2.1 Surficial Geology
Along the north coast of Puerto Rico, the basement rock is predominantly
limestone. Outcrops commonly occur near shore with the number diminishing in
deeper waters (EPA 1982). Beach rock deposits (sand that has been cemented
with iron oxides and/or precipitated calcium carbonate) are also common within
the Arecibo study area (Guillou and Glass 1957).
Overlying the limestone and beach rock are several meters of sediments
derived from land and marine sources. In areas of rapid currents or extensive
wave action, such as in the beach zones adjacent to Arecibo (Figure 3-7), the
sediments are predominantly coarse-grained materials, composed of quartz
particles or shell fragments. Quartz grains originating from rock weathering
and alluvial transport are found near river mouths along this coast (EPA
1982). Sediments composed mostly of shell fragments and other calcium
carbonate materials formed by marine organisms are more typically present in
offshore areas.
3-14
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18*45"
J
O
W50'
~~r~
66"40'
66*30'
SUBSURFACE AND NEAR-BOTTOM TRANSPORT (cm/s)
(DEPTHS OF OBSERVATIONS IN METERS)
18*45'
18*40'
E = EBB TIDE F » F1X)W TIDE
® PUERTO RICO DPW (1974) 7/71. 10/71
(2) BLACK & VEATCH (1975) 10-11/74
(5) PUERTO RICO NUCLEAR CENTER (1975) PRNC-197 1-2/74
I **40'
18*35'
18*35'
300 fm
»,/¦
-100 fm x
irjo-
\ J3K-'
-s/
.15 35.1 S\_ ^ /
18*30*
ARKCIBO
NAUTICAL MILES
I I I 1 1 1
0 1 2 3 4 5
66*50'
66*40'
66*30'
FIGURE 3-6. SUBSURFACE AND NEAR-BOTTOM TRANSPORT, ARECIB0 STUDY AREA
-------
46*50* 66*40' 66*30'
FIGURE 3-7. SEDIMENT SAMPLING POINTS AND IDENTIFIED SEA-FLOOR
SEDIMENTS OFF AREC1BO
-------
Fine grained sediments are found where currents are relatively slow and
where sediment-laden rivers discharge into the sea. At Arecibo, the Rio
Grande de Arecibo frequently floods and causes extensive sedimentation and
shoaling in Arecibo Harbor (COE 1980e). Fine-grained sediments replace the
nearshore sand along the coast within 1 to 2 nmi of the harbor, reflecting the
river's influence.
3.1.2.2 Sea-Floor Characteristics and Sediment Textures
Sediment sampling off Arecibo during the 1984 Survey Cruise indicates
that the bottom is soft past the 100-fathom depth (Figure 3-7). This verifies
earlier studies (Schneidermann et al. 1976) of bottom types on the Puerto Rico
shelf.
The 22 samples collected in the Arecibo area contained approximately 60
percent silt, 30 percent clay, and less than 10 percent sand. The measurement
scale used is the Wentworth scale (Levinton 1982), in which silt is composed
of particles from 0.0039 to 0.0313 mm in longest dimension. Sand particles
are larger, ranging from 0.0625 to 1.0 mm. Clay particles are much smaller,
ranging from 0.00024 to 0.00195 mm in longest dimension.
Interim Site - The sediments at the Interim Site are more coarse grained
(e.g., sandier) than in other areas adjacent to the site. Samples collected
within the Interim Site contained from 53 to 68 percent sand. This probably
reflects the predominantly sandy nature of the material dredged in the past
from Arecibo Harbor and dumped at the Interim Site (COG 1980e).
Alternate Site 1 - The sediments are predominantly silty, ranging from 59
to 85 percent silt, less than 10 percent sand, and the remainder clay. The
sediments appear to be uniformly silty within this site.
Alternate Site 2 - The bottom sediments are predominantly silty with 55
to 70 percent silt, 25 to 33 percent clay, and 8 to 19 percent sand.
3-17
-------
3.1.2.3 Sediment Mineralogy
Mineral compositions of the sediments at the interim and alternate sites
are correlated with the sediment sources and particle size distributions at
the sites.
The sand-sized material is likely to be composed of over 60 percent
quartz, magnetite particles, and possibly hornblende particles that have been
weathered from rocks on the island (Schneidermann et al. 1976; Guillou and
Glass 1957; Kaye 1959). The other 40 percent of this sand fraction is calcium
carbonate particles from shell fragments and other marine skeletal materials
(Schneidermann et al. 1976). Sand particles can be considered relatively
inert; they do not react chemically with each other or with the sea water to
any great extent.
The silt fraction contains organic matter derived from marine and
terrestrial sources. Silt particles are not cohesive or sticky, and their
tendency to absorb metals or contaminants is very limited when compared to
clay particles. The clay fraction of mixed sediments such as those at Arecibo
has several properties that determine the general texture, transport behavior,
and density of the sediments. First, a very small percentage by weight of
clay in the sediment can have a marked effect on the physical properties of
the sediment. Clays and partially clayey sediments are more cohesive than
non-clayey sediments. Second, clays exhibit high degrees of cation exchange
capacity, the capacity to temporarily adsorb ions onto the electrochemically-
charged surfaces of the clay particles. For this reason, clays are more
likely than other sediments to adsorb innocuous ions, such as potassium, or
toxic ions, such as cadmium or other heavy metals from the water column
(McCarthy 1977). Sediments of 25 to 33 percent clay, such as those found at
alternate site 2 for Arecibo, will exhibit substantial increases in density
and cohesiveness compared to sediments of adjacent locations which contain a
smaller percentage of clay. Sediment characteristics will affect the type of
benthic organisms inhabiting the site, and thus may influence the magnitude of
ecological disturbance that may occur if dredged material is released at a
given site (see discussion of soft-bottom benthos, earlier in this chapter).
3-18
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3.1.3 Water Quality
Surface waters throughout the Arecibo study area are clear, warm, oxygen-
saturated and nutrient depleted. Below the surface mixed layer, oxygen
remains undepleted, and nutrient levels become very high. In summary, water
quality in the area of the interim and alternate sites is excellent, and is
typical of tropical open-ocean conditions.
3.1.3.1 Turbidity
Secchi disc depth readings taken from shallow (<15 m) nearshore waters
(<2 nmi from shore) near Barceloneta (8 to 11 nautical miles east of Arecibo)
are presented in Figure 3-8 (Puerto Rico Department of Public Works 1974).
Secchi depths range from 5-24 m. Nearshore readings taken in studies of a
proposed North Coast Nuclear Plant Unit No. 1 Site adjacent to Punta Las Tunas
(5-7 miles east of Arecibo) ranged from 7-20 m (Puerto Rico Nuclear Center
1975). The lower values, indicating turbid water, were found at sites closest
to shore; the higher values, indicating greater clarity, were found further
from shore. The turbidity levels for Barceloneta are associated with runoff
from the Rio Grande de Arecibo and the Rio Grande de Monati (Puerto Rico
Department of Public Works, 1974). Transparency measurements indicated a
transmission of 97-100% per 10 cm at all times.
3.1.3.2 Dissolved Oxygen
Dissolved oxygen concentrations are consistently at or near saturation
levels in the surface water (Wood et al. 1975b). Figure 3-9 presents the
average dissolved oxygen depth profiles by season at Punta Manati, 11 miles
east of Arecibo, for 1973 and 1974. Some super-saturation was measured at
depths of 25-75 m because of photosynthesis. Oxygen levels decrease slightly
with depth. The greatest average dissolved oxygen values, except for the
winter season, were found around 100 m (5.0 ml/1). The oxygen minimum
occurred at about 225 m (4.0 ml/1) for all seasons except fall, when a
distinct minimum was measured at 150 m (4.0 ml/1). Generally, there is very
little seasonal change in dissolved oxygen.
3-19
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• J OUT
7 JULY
WBARCCLONETA /
I
NAUT Ml
FIGURE 3-8. SECCHI DISK READINGS IN METERS FOR NEAR SHORE WATERS NEAR BARDRLONETA, JULY 1971
Source: Puerto Rico Department of Public Works 1974.
-------
DISSOLVED OXYGEN ml/1
3 4 5 6
FIGURE 3-9. AVERAGED DISSOLVED OXYGEN DEPTH PROFILES, BY SEASON,
AT PUNTA MANATI, 1973 AND 1974
Source: Wood et al. 1975b.
3-21
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3.1.3.3 Nutrients
Nutrient levels in surface waters exhibit little seasonality, reflecting
the relatively stable marine conditions associated with Puerto Rico's tropical
climate. Surface waters are typically low in nutrients (phosphate, nitrate,
and silicate), but concentrations increase with depth below the pycnocline.
Seasonal concentrations of reactive phosphate measured near Punta Manati
are presented in Figure 3-10 (Wood et al. 1975b). Surface water concentra-
tions, although typically very low (0.05 ug-at P/l) throughout the year, vary
from a summer low of 0.02 ug-at P/l to a winter high of 0.09 ug-at P/l).
There is little seasonal variation in phosphate levels. Phosphate values are
constant throughout the upper mixed layer and through the pycnocline to about
200 m. Peak values at the deepest point sampled were about 0.5 ug-at P/l. A
similar pattern was observed at the North Coast Nuclear Plant #1 site loca-
tion. Surface layer concentrations of phosphate at this site were below ug-at
P/l and remained constant to approximately 150 m. Below 150 m, phosphate
concentration gradually increased with depth (Puerto Rico Nuclear Center
1975).
Fall concentrations of nitrate measured near Punta Manati are presented
in Figure 3-11 (Wood et al. 1975b). At the deepest station sampled (Station
C), the surface nitrate concentration was 0.3 ug-at N/1. The concentration
remained constant to approximately 100 m and then gradually increased to
14 ug-at N/1 at 300 m. At the North Coast Nuclear Plant #1 site (Puerto Rico
Nuclear Center 1975) nitrate concentrations at the deepwater site increased
almost linearly with depth from nearly 0 at 100 m to 27.9 ug-at N/1 at
1,000 m. This profile is typical for the North Atlantic Ocean (Puerto Rico
Nuclear Center 1975).
Studies conducted off Barceloneta, about 8 to 11 nmi east of Arecibo
(Puerto Rico Department of Public Works 1974), measured silica concentrations
ranging from 0-0.23 mg/1 S/l in surface waters. No data on subsurface silica
concentrations were found for thi8
3-22
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REACTIVE PHOSPHATE |jg-at. P/l
0 0-1 02 03 04 0-5 06
FIGURE 3-10. AVERAGED REACTIVE PHOSPHATE DEPTH PROFILES, BY SEASON,
AT PUNTA MANATI, 1973 AND 1974
Source: Wood et al. 1975b.
3-23
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Nitrate pg-at.N/l
2 4 6 8 10 12 14 16 18
100
D
E
P
T
H
m
200-
300-
PMA-3
Oct. 31,1974
A - Nearshore Station
B - Depth about 125 m
C - Depth about 325 m
FIGURE 3-11. PLOT OF NITRATE VS. STANDARD DEPTH FOR THE FALL
SEASON, AT PUNTA MANATI, 1974
Source: Wood et al. 1975b.
3-24
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TTAXA
SCNT
SHNWVR
PIELOU
GRAVEL
SAND
SILT
CLAY
FINES
OPFT
e . 36007
0.0651
27
0.49266
0.0090
27
-0.44761
0.0192
27
-0.35742
0.0672
27
-0.49332
0.0089
27
-0 38064
0.0501
27
0.20736
0.2993
27
0.42428
0.0274
27
-0.35797
0 0668
27
-0.35017
0.0734
27
-0.42362
0.0277
27
-0 40209
0.0376
27
0 . 24168
0.2246
27
0. 50053
0.0078
27
-0.42463
0.0273
27
-0.40919
0.0341
27
-0.49971
0.0080
27
-0.40204
0.0376
27
0.15529
0.4392
27
0.46601
0.0143
27
-0.37337
0.0551
27
-0.41512
0.0313
27
-0.46442
0.0147
27
-0.37936
0.0510
27
Table 3-1 Correlation Matrix for Sediment Grain Sice, Biological Parameter*
and Station Depth from the March, 1984 EPA/JRB Survey Offshore of
Arecibo , Puerto Rico. (Correlation coefficients are listed first
with significance levels listed second and the number of comparison*
third). TTAXA ¦ total number of taxa, SCNT ¦ total numbar of
individuals of all taxa. SHNWVR ¦ Shannon - Weaver Diversity
Index, PXSLOU ¦ Pielou'a Iveness Index.
3-26
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3.1.4.3 Mangrove Breeding and Nursery Areas
Commercially important marine fish of Puerto Rico's north coast, such as
pompano, mullet, and mojarra, use mangrove estuaries as breeding areas and
nursery grounds (Austin 1971). Mangrove environments, with their variable
salinities and temperatures and limited spatial extents, are not primary
year-round habitats for adult fish of most species. However, they are very
suitable for the development of juveniles (Austin 1971). The north coast has
several particularly extensive mangrove areas. One of these, the red mangrove
area along Cano Tiburones, is immediately adjacent to Arecibo (see Figure
3-12).
According to Austin and Austin's 1971 study of fish feeding habits in the
Cano Tiburones area, "a very large invertebrate population is present; in par-
ticular, the crustacean Macrobrachium carcinus" (the commercially valuable
fresh or brackish-water prawn). The authors noted that, "All of the carni-
vorous fish examined, which feed on crustaceans, had consumed primarily
juvenile M^_ carcinusindicating that as a juvenile this mangrove crustacean
is an important component of the food chain supporting commercially important
fish. Thus, there is evidence to suggest that Cano Tiburones provides impor-
tant productivity inputs to open-water marine food chains, including those of
commercially important species, around Arecibo Harbor.
3.1.4.4 Preserves and Reserves
As discussed previously, some mangroves that provide nursery areas for
commercially valuable fish are located along the Arecibo coast (see Figure
3-13). There are three coastal areas near Arecibo designated by the
Commonwealth of Puerto Rico as critical wildlife areas. These are the
Guajataca Cliffs critical habitat area, 9-11 miles along the coast to the west
of the harbor, the Carrizales Mangrove Swamp, 4 miles west of the harbor and
the Cano Tiburones Swamp, 1-8 miles to the east.
3.1.4.5 Threatened and Endangered Species
Two general types of animals with marine or semi-marine habitats in
Puerto Rico include these federally designated endangered species: Sea
turtles and the brown pelican.
3-27
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66°50'
J
[N1
LEGEND
Important Commercial
Fishing Areas
- Important Sport
Fishing Areas
06- ,~ ¦ Coral Reefs/Bottom
Areas
J J J « Nursery Areas
ARECIBO
Cano Tiburones
Nautical Miles
TTTT1
66°50' 66°40'
FTGimK 3-12. LIVING MARINE RESOURCES NEAR ARECIBO
66°30*
-------
66°50'
66°AO'
66°30'
18
45'
18
40'
18
35'
18
30'
LEGEND
- Public Beaches
- Other Beaches
- Marinas
•.*.***••* - Wildlife Areas
• • • •
¦y^rV " Co*»nwealtta Forests
~ - Wrecks
A » Diving and Spearfishing
- Surfing Areas
18
45*
18
40'
18°
35'
100f»%_,''
13 (T)
lttjil.--
Guajataca
Cliffs
Carrizales
Mangrove
18"
30'
ARECIBO
Tiburones
Swamp
Nautical Miles
oTTTTl
66°50' 66°40' 66°30'
FIGURE 3-13. RECREATIONAL AREAS, PRESERVES AND SHIPWRECKS NEAR ARECIBO
-------
Hawkbill sea turtles (Eretmochelys imbricata), green turtles (Chelonia
mydas), leather back turtles (Dermochelys coriacea), and loggerheads (Caretfca
caretta) forage in the mangroves and seagrass beds of the Puerto Rican coast
and nest along the beaches. It has not been reported whether sea turtles
forage in the mangrove areas or nest on the beaches near Arecibo.
The brown pelican historically nested on Enrique Key and Turrumote Key.
They often live in mangrove habitats and only rarely move offshore. It has
not been reported to what extent brown pelicans inhabit shoreline areas
adjacent to the Arecibo study area.
A list of threatened or endangered species identified in the Arecibo
study are is presented in Table 3-6.
3.1.5 Recreational Areas
With the exception of some important game-fish fishing areas, which will
be discussed in Section 3.1.9, few recreational areas exist within a 15-mile
radius of Arecibo. There are three swimming beaches to the east of Arecibo,
with the closest approximately 8 miles from the harbor (see Figure 3-13).
Although there is large surf along much of the north coast, recreational
surfing on this coast is limited primarily to areas beginning 40 miles to the
east of Arecibo, near San Juan. In general, most recreational establishments
for scuba diving, snorkeling, and sailing on the north coast are located near
the prime tourist area of San Juan. According to the Puerto Rico Coastal
Management Plan (DOC 1978), no marinas are located along the Arecibo
coastline.
3.1.6 Shipping Lanes
Between 1979 and 1981, the Seventh Coast Guard District evaluated the
need to establish formal shipping lanes for Puerto Rico. Their report (46 FR
48376, October 1, 1981) concluded that in some areas vessel traffic had been
divided naturally into directional lanes according to prevailing currents. In
other areas, traffic density and use conflicts did not warrant the designation
of specific lanes. Therefore, there are no formal shipping lanes off Arecibo
or other areas of Puerto Rico.
3-JO
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3.1.7 Mineral Resources
Although some seismic exploration for oil and gas has been conducted
along the north coast of Puerto Rico, including the Arecibo ZSF, no oil or gas
deposits have been identified within the ZSF or at the sites under considera-
tion (PR Geological Survey 1983).
Quartz (siliceous) sands are in demand in Puerto Rico as constituents of
concrete. Calcareous sands (from coral, limestone, and shell fragments) are
used in plasters. The supplies of quartz sands in the islands are limited.
Most mineable sand dunes have been mined out, and mining of the beaches is
prohibited. As a result of these shortages, the USGS performed a survey to
locate offshore sand resources. The survey located sources sufficient to meet
the needs of the island (USGS 1983).
There are known deposits of magnetite sands south of the ZSF. No data
were currently found describing the northward extent of these sands. Thus, it
is possible that the deposits may extend into the sourthern part of the ZSF
near the mouth of the Rio Grande de Arecibo closest to the interim site.
There has been interest in using offshore quartz sand deposits to alleviate
shortages, but'mining of these sands is not presently considered to be
economically feasible, even though the sands may contain up to 25 percent
magnetite (PR Geological Survey 1983; Guillou and Glass 1957). No quartz
deposits have been identified at any site in the Arecibo ZSF.
3.1.8 Shipwrecks or Other Features of Historical or Cultural Importance
No shipwrecks have been identified in the Arecibo study area (University
of Puerto Rico 1974). No other features of historical or cultural importance
have been identified in the study area.
3.1.9 Fisheries of the Arecibo Area
The bulk of the Puerto Rican commercial fishing fleet consists of small
boats fishing for reef-associated species on the islandic shelf (see Section
3.0.4). The north coast is generally the least active fishing area in Puerto
Rico, because heavy seas and relatively high winds make small-boat fishing on
3-31
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this coastline impractical on many occasions. Also, corals are poorly
developed on this coastline (see Section 3.0.2). Beach seining is a common
fishing method used along the northern shore (particularly in the area shown
as a "commercial fishing area" in Figure 3-12). On occasions when "blue-
water" (clear water, typical of offshore conditions) occurs within about 3
miles of the coastline, sport fishing boats search for marlin and other large
game fish (CODREMAR* 1983; Bird 1960). Therefore, there is some sport fishing
within the ZSF and near the interim and alternate sites at various times
throughout the year.
3.2 CHARACTERIZATION OF THE AFFECTED ENVIRONMENT FOR MAYAGUEZ
3.2.1 Oceanographic and CIimatological Characteristics
3.2.1.1 Bathymetry
The width of the shelf along the west cqast of Puerto Rico is quite
variable (as seen in Figures 3-14 and 1-2). The shelf extends approximately
16 km from the shoreline south of Mayaguez, but narrows to approximately 5
km directly north of the harbor. It narrows gradually to about 2 km width at
Punta Cadena, about 10 nmi to the north, and then remains about 1 to 2 km wide
as far as Punta Higuero, 16 km north of Mayaguez. The zone of siting feasi-
bility (Figure 2-6) is thus bordered by shallow waters to the south and by
land on the north, where the coastline turns in an east-west direction out to
Punta Higuero. To the northwest, the bottom slopes at a 2° gradient to a
maximum depth to the west of 850 m; and then becomes more shallow as it
approaches Isla Desecheo, about 25 km from site 2.
3.2.1.2 Climatology
As in most of Puerto Rico, there are only small seasonal and diurnal
variations in the climate near Mayaguez. Because hurricanes typically travel
~Corporation for the Development of Fluvial, Lacustrine, and Marine Resources,
Commonwealth of Puerto Rico, Department of Natural Resources.
3-32
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Distance (km)
FIGURE 3-14. BATHYMETRIC PROFILES OFFSHORE FROM PLAYA GRANDE AND
PUNTA ARENAS
3-33
-------
from east to west over Puerto Rico, the number of severe storms is less on the
west coast than at eastern locations such as Yabucoa. Wind data from Ramey
Field (32 km north of Mayaguez) for the period 1940-1953 show surface winds
predominantly from the east or northeast, with an annual hourly maximum
velocity of 7.0 m/s and an annual hourly minimum of 3.3 m/s (Puerto Rico Water
Resources Authority, 1959). Near Mayaguez, however, the sea breeze can be
opposite to the easterly trade winds, frequently becoming dominant and result-
ing in on-shore westerly winds (Puerto Rico DPW 1974).
3.2.1.3 Hydrography
Temperature data were gathered from six deep-water sites at Punta Higuero
(Wood et al. 1975a), 22 km (12 nmi) north of Mayaguez (Figure 3-15). The
maximum seasonal surface temperature variation is 2°C, and little seasonal
change occurs below depths of 150 m. The thermocline in winter and spring is
deeper than the summer and fall thermocline.
Salinity profiles from Punta Higuero show an increase in salinity from
the surface to 150 m, and a slight decrease below 150 m (Figure 3-16). This
pattern does not change seasonally. The highest surface salinity occurs in
the spring due to dry season evaporation; wet season dilution causes minimum
surface salinity in the fall. In the 50-100 m depth range, the salinity is a
minimum in the winter, when storms cause this subsurface water to mix with the
low salinity surface water, and increases steadily throughout the rest of the
year. As mentioned earlier, no significant seasonal effects are observed
below depths of 150 m.
The density profiles resulting from these temperature and salinity values
for the Punta Higuero area are shown in Figure 3-17. The winter and spring
profiles show a deeper pycnocline and a smaller density gradient than in
summer and fall. The figure shows a mixed surface layer of approximately 100
meters and an average density gradient of 9 x 10 ^/m. In comparison, summer
and fall are characterized by a mixed surface layer of 50 m and an average
density gradient of 2 x 10 ^/m.
3-34
-------
TEMER4TURE °C
16 18 20 22 24 26 28
FIGURE 3-15. AVERAGED TEMPERATURE PROFILES, BY SEASON, OFF PUNTA
HIGUERO, 1973 AND 1974
Source: Wood et al. 1975a.
I
3-35
-------
34
D
E
P
T
H
m
100-
200-
300-
SALINITY •/••
35 36
J L
PHI
Winter 1
Spring 2
Summer 3
Fall 4
37
_j
FIGURE 3-16. AVERAGED SALINITY PROFILES, BY SEASON, OFF PUNTA
HIGUERO, 1973 AND 1974
Source: Wood et al. 197 5a.
3-36
-------
DENSITY Ot
20 22 24 26 28
n
u
3V41I I2
«
100-
iNaSay
D
\NA
E
P
T
H
%
m
*
200-
1
PHI 1
Winter 1 l\2
Spring 2 11
Summer 3 3II
Foil 4 1
300-
FIGURE 3-17. AVERAGED DENSITY PROFILES, BY SEASON, OFF PUNTA
HIGUERO, 1973 AND 1974
Source: Wood et al. 1975a.
3-37
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3.2.1.4 Circulation
Surface currents north and south of Puerto Rico generally travel toward
the west due to the easterly trade winds. The current along the south coast
turns northward through Mona Passage and is typically to the north off the
west coast of the island. However, numerous eddies and reversals occur in the
nearshore waters due to complex bottom topography, tides, wind fluctuations,
and surface runoff (Wood et al. 1975a).
Surface currents in the Mayaguez study area tend to flow northward at
flood tide and southward at ebb tide. Figure 3-18 shows nearshore surface
current data near Mayaguez and Punta Ostiones (Puerto Rico DPW 1974) and near
Punta Higuero (Wood et al. 1975a). The surface-current data at both sites
show seasonal differences in current direction, with flow always roughly
parallel to the shore. Net surface current speeds at Punta Higuero are
approximately 30 cm/sec; data near Mayaguez showed net velocities of about
15 cm/sec. Subsurface and near-bottom current measurements at nearshore loca-
tions monitored for the Punta Ostiones study were generally parallel to the
shore at about 15 cm/s. Other subsurface current measurements are shown in
Figure 3-19. Directions were south or southeastward, at speeds of about 15
cm/sec.
3.2.2 Geologic and Geochemical Characteristics
The interim and alternate sites at Mayaguez all contain areas of soft
bottom composed of fine-grained sediments. The following sections describe
the surficial geology, the bottom types, grain size distributions, and geo-
chemical characteristics of sites in the Mayaguez.
3.2.2.1 Surficial Geology
The basement rock underlying most of the Mayaguez ZSF is limestone, with
numerous geologic faults (Morelock et al. 1983; Briggs and Akers 1965). Over-
lying the limestone in most areas of the ZSF is a thick blanket of sediments.
Seismic profiles indicate sediment thicknesses of 100 to 200 meters (Morelock
et al. 1983).
3-38
-------
67*20' 6VW
FIGURE 3-18. SURFACE LAYER TRANSPORT, MAYAGUEZ STUDY AREA
3-39
-------
67*20' 67°10'
FIGURE 3-19. SUBSURFACE AND NEAR-BOTTOM TRANSPORT, MAYAGUEZ STUDY AREA
3-40
-------
Much of the area is covered by sediments of terrestrial rather than
marine origin. Three major rivers discharge sediments into the ZSF. The
largest river, the Aftasco River, drains an area covering about 340 square
kilometers. Five major floods from this river have occurred since 1889. Dur-
ing these major floods and the smaller annual floods, large quantities of
sediments are moved from the estuaries into Aflasco Bay, in the eastern part of
the ZSF. Two smaller rivers (Yaguez River, which flows through Mayaguez, and
the Guanajibo River to the south) also contribute sediments to the western
coast, but in far smaller volume than the Arfasco (Morelock et al. 1983).
3.2.2.2 Sea Floor Characteristics and Sediment Textures
Acoustic surveys during the 1984 survey cruise indicated several areas of
hard bottom within the ZSF (Figure 3-20). Preliminary acoustic data indicated
that 10 of the 22 stations occupied by the ship in the ZSF were hard bottom
locations. These data do not preclude the possibility of thin (less than
10 cm) layers of soft sediments overlaying the hard substrate. In areas along
the western coast where sediment inputs are relatively high, most of the
bottom is likely to be covered with redistributed sediments. Even so, hard
bottoms can occur on topographic highs and in areas having high current
energies. The presence of hard substrate is not surprising because sediment-
covered or partially sediment-covered patch reefs are common in this part of
the western coast, and wave refractions and current patterns along this coast
are complex (Morelock et al. 1983), which could result in scouring bottom
currents. These factors could account for the absence of a thick sediment
cover over old reefs or bedrock outcrops in parts of the ZSF.
Samples taken from the alternate sites indicated soft bottom conditions;
however, one sample on the eastern part of the interim site indicated a hard
bottom.
The 22 sediment samples collected in the Mayaguez ZSF were predominantly
silt. The samples contained an average of 76 percent silt, 40 percent clay,
and 13 percent sand. Sediments collected at the various sites were as
follows:
3-41
-------
FIGURE 3-20. SEDIMENT SAMPLING POINTS AND IDENTIFIED SEA-FLOOR SEDIMENTS
IN MAYAGUEZ ZSF
3-42
-------
Interim Site - The sediments at the interim site are fine-grained mix-
tures of silts and clays. They range in composition from 5 to 26 percent
sand, 58 to 61 percent silt, and 17 to 36 percent clay. On the eastern part
of the interim site, one sample test indicated a hard bottom. Depths range
from 43 to 143 fathoms.
Alternate Site 1 - The sediments are silty clays with more than 60 per-
cent silt, more than 25 percent clay, and 5 percent or less sand. The depth
in the center of the site is 180 fathoms and the bottom slopes westward.
Alternate Site 2 - The sediments are silty clays very similar in composi-
tion to those from alternate site 1. The depth is about 23 fathoms in the
center of the site, and the bottom slopes to the northwest.
Alternate Site 3 - The fine-grained sediments at this site consist of 10
percent or less sand, about 70 percent silt, and 20 percent clay. The depth
ranges from over 150 fathoms to over 180 fathoms, and the bottom slopes to the
northwest.
3.2.2.3 Sediment Mineralogy
Sediments of terrestrial origin in the ZSF come from weathered volcanic
and metamorphic rocks that have been transported via rivers into coastal
waters (Meyerhoff 1932; Morelock et al. 1983).
The sand fraction from Anasco River consists of quartz from andesitic and
granitic intrusive rocks, along with associated resistant minerals such as
feldspar. Other minerals from volcanic aBh, tuff, pyroclastics, and conglo-
merates may also be present. Sands from the Yaguez River are dark, due to
their volcanic derivation. They contain minor amounts of chromite derived
from serpentine (Morelock et al. 1983; Schneidermann et al. 1976; Guillou and
Glass 1957). About 97 percent of the sand fraction on the shelf off the
Anasco Bay is of terrestrial origin; the remainder is carbonaceous skeletal
material (Morelock et al. 1983).
3-43
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The silt-sized particles are composed of very fine river sands and
organic materials, derived primarily from terrestrial plants (Morelock et al.
1983).
The clays found in the Afrasco River and Anasco Bay are kaolinite,
montmorillonite, chlorite, and illite (Morelock et al. 1983). It is likely
that smaller volumes of the similar clays are discharged from Yaguez River as
well. Montmorillonite has a very high cation exchange capacity, a measure of
a clay's ability to adsorb positively charged ions onto the electrochemically
charged surfaces of the crystal structure (McCarthy 1977). The clay particles
in the sediments can adsorb toxins from the water column. Because of this
property, clays could contribute to the contaminant binding properties of
sediments at various sites.
3.2.3 Water Quality
Surface waters throughout the Mayaguez study area are clear, warm, oxygen
saturated and nutrient depleted. Below the surface mixed layer, oxygen
remains undepleted, and nutrient levels become very high. In summary, water
quality in the area of the interim and alternate sites is excellent, and is
typical of tropical open-ocean conditions.
3.2.3.1 Turbidity
Secchi disc depth readings taken from shallow (<15 m) nearshore waters,
less than 2 nm offshore near Mayaguez, ranged from 6-29 m (Puerto Rico
Department of Public Works 1974). The lower values, indicating turbid water,
were taken at sites closest to shore; the higher values, indicating greater
clarity, were found further from shore. Based on these measurements, it
appears that the waters in the ZSF are optically clear and contain little
suspended material (EPA 1981).
3.2.3.2 Dissolved Oxygen
Dissolved oxygen concentrations are consistently at or near saturation
levels in the surface waters (Wood et al. 1975a; Puerto Rico Nuclear Center
1974). Figure 3-21 presents the average dissolved oxygen depth profiles by
3-44
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DISSOLVED OXYGEN ml/1
0
100
D
E
P
T
H
m
200
300
FIGURE 3-21. AVERAGED DISSOLVED OXYGEN DEPTH PROFILES, BY SEASON,
AT PUNTA HIGUERO, 1973 AND 1974
Source: Wood et al. 1975a.
3-45
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season at Punta Higuero, approximately 9 miles north of Mayaguez, for 1973 and
1974. Little change in surface dissolved oxygen concentration by season can
be observed. Oxygen levels decrease slightly with depth, but remain high (on
the order of 4.0-4.5 ml/1). Some supersaturation waa measured at depths of
25-75 m, apparently as a result of increased photosynthesis. The greatest
dissolved oxygen values (4.7—5.0 ml/1) were measured at approximately 100 m.
Minimum dissolved oxygen concentrations were measured at around 250 m for all
seasons except winter, when minima were recorded at around 150 m. With the
exception of the winter minimum, there was very little seasonal change in
surface or deeper water dissolved oxygen concentrations.
3.2.3.3 Nutrients
Nutrient levels in surface waters exhibit little seasonality, reflecting
the relatively stable marine conditions associated with Puerto Rico's tropical
climate. Surface waters are typically low in nutrients (phosphate, nitrate,
and silicate), but concentrations increase with depth below the pycnocline.
Seasonal concentrations of reactive phosphate measured near Punta Higuero
are presented in Figure 3-22 (Wood et al. 1975a). Surface water concentra-
tions are typically low (0.05 ug-at P/l) throughout the year. Slightly higher
values were measured during the spring season (surface water 0.11 ug-at P/l),
with concentrations up to 0.13 ug-at P/l at 50 m. Phosphate values are
generally constant throughout the upper mixed layer and through the pycnocline
to about 100 m. The phosphate concentration steadily increased with depth
below 100 m. Peak values at the deepest point sampled occurred in the spring
(0.57 ug-at P/l) and were lowest in the fall (0.37 ug-at P/l).
Summer and fall concentrations of nitrate measured near Punta Higuero are
presented in Figure 3-23. The nitrate concentration was less than 1 ug-at N/1
from the surface down to 75 m in the summer and 35 m in the fall. Nitrate
values were greater in the fall (between 50 and 150 m) than in the summer.
Little seasonal difference was found below 150 m. The concentrations of
nitrate increased with depth, ranging from 2 ug-at N/1 at 100 m to greater
than 13 ug-at N/1 at 300 m.
3-46
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FIGURE 3-22. AVERAGED REACTIVE PHOSPHATE DEPTH PROFILES, BY SEASON,
AT PUNTA HIGUERO, 1973 AND 1974
Source: Wood et al. 1975a.
3-47
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FIGURE 3-23. NITRATE DEPTH PROFILE FOR THE SUMMER AND FALL SEASONS
AT PUNTA HIGUERO, 1974
Source: Wood et al. 1975a.
3-48
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Studies conducted in nearshore waters off Mayaguez measured silica con-
centrations ranging from 0 to 0.33 mg/1 in surface waters (Puerto Rico
Department of Public Works 1974). No data on subsurface silica concentrations
were available for this area.
3.2.4 Biota
Species identified in the Mayaguez study area are included in the species
list presented in Table 3-5.
3.2.4.1 Benthic Invertebrates
Information presented here is based on analyses of the biological sampl-
ing conducted on EPA's 1984 survey cruise in Puerto Rico (JRB Associates).
The hard-bottom communities, as observed in bottom photographs, were
sparse, consisting of sponges, gorgonians and unidentified encrusting
organisms. These communities appeared to be limited in distribution by
generally high levels of fine-sediment cover.
The soft-bottom community in the Mayaguez region was dominated by
polychates (174 taxa), followed by crustaceans (71 taxa), molluscs (51 taxa,
primarily gastropods and pelecypods), 14 minor taxa (primarily sipunculids)
and echinoderms (10 taxa). The majority of the 320 total taxa were deposit
feeders, typical of fine-grained sedimentary environments generally occurring
at the Mayaguez site. The mean number of taxa per sample (station and repli-
cate) was relatively high (50). The number of individuals per sample for each
taxon was relatively low, the majority occurring in densities of only one to
2
five individuals per 0.065 m . The species having the highest densities were
the polychaetes Levinsenia uncinata, Melinna sp. Euchone sp. D and prionospio
sp. F; the pelecypod Nuculana sp. F; and the sipunculid Golfingia
tricocephalad.
The soft-bottom community was dominated by deposit feeding organisms
(primarily polychaetes) typical of the fine-grained sediments occurring at the
site. The number of taxa and number of individuals per sample were quite
variable, as indicated by the variability of diversity values among the
3-49
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different samples. The types of taxa were relatively different among samples,
suggesting a patchy distibution of many organisms. Two station groups were
observed based on the results of cluster analysis (Table 3-2); however, the
groups did not correspond to any obvious trends in sediment grain size
distribution and were not indicative of any influence from past dredged
material disposal at the Ponce DMDS.
3.2.4.2 Coral Reefs
Coral reefs are well-developed along the middle and southern portions of
Puerto Rico's west coast (Almy and Carrion Torres 1963). None of the alter-
nate sites are directly over any of the major reefs known to exist in the
Mayaguez study area (see Figure 3-24). The alternate sites were selected to
exclude all hard-bottom areas that were tentatively identified in other parts
of the ZSF by acoustic measurements during the 1984 survey cruise. However,
the eastern half of the interim site is adjacent to the most seaward of the
three major coral reefs off Mayaguez (Figure 3-24).
3.2.4.3 Mangrove Breeding and Nursery Areas
Commercially or recreationally important species of marine fish, such as
ladyfish, pompano, mullet, and mojarra, use the mangrove estuaries in the
Mayaguez study area as nursery grounds (Austin 1971). The mangrove environ-
ment, while inhospitable to many adult fish, is suitable for the development
of juveniles (Austin 1971). The west coast, and the Mayaguez area in parti-
cular, have many rivers and streams and a large volume of freshwater drainage
to the sea because of heavy rainfall in the adjacent mountains. Many of these
drainages form deep brackish-water estuaries bordered by mangroves. An impor-
tant mangrove habitat is located 4.5 half miles south of Mayaguez (Figure
3-24) where the Guanajibo River flows into Mayaguez Bay. A second mangrove
habitat, Joyuda Lagoon, is located about 5 miles south of the harbor. The
mouth of the Anasco River, 4 miles north of Mayaguez, also has limited
mangrove growth.
3-50
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TTAXA
SCNT
SHNWVR
PIELOU
GRAVEL
-0.1864 1
0.6646
19
-0.09862
0.6879
19
-0.05493
0.8233
19
-0.02387
0.9227
19
SAND
ft. 07749
0.7525
19
-0.07734
0.7530
19
-0.07158
0.7709
19
-0.14833
0.5445
19
SILT
0. 13186
0.5905
19
0.23651
0.3296
19
0.24607
0.3099
19
0.29366
0.2224
19
CLAY
-0.95935
0.2836
19
1341.7
0.5839
19
-0.15382
0.5295
19
-0.08749
0.7217
19
FINES
-0.07654
0.7555
19
0.07804
0.7508
19
0.07193
0.7698
19
0.14835
0.5444
19
DPFT
-0.35236
0. 1390
19
-0.45368
0.0511
19
-0.50116
0.0288
19
-0.55726
0.0132
19
Table 3-2 Correlation Matrix for Sediment Grain Size, Biological Parameters
and Station Depth from the March, 1984 EPA/JRB Survey Offshore of
Mayaguez, Puerto Rico. (Correlation coefficients are listed first
with significance levels listed second and the number of comparisons
third). TTAXA ¦ total number of taxa, SCNT ¦ total number of
individuals of all taxa, SHNWVR • Shannon - Weaver Diversity
Index, PIELOU ¦ Pielou's Eveness Index.
3-51
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67°30'
67°20'
67°10'
T
i i
i >
< »
• lOOfm .
Tourmaline
Reef
LEGEND
Important Commercial
Fishing Areas
Las
Coronas
- Important Sport
Fishing Areas
##,~» Coral Reefs/Bottom
Areas
• • • " Nursery Areas
Nautical Miles
(TTTTTl
18°
25'
18°
20'
18°
15'
18
10'
18
05'
18°
00'
67°30'
67°20'
67°101
FIGURE 3-24. LIVING MARINE RESOURCES NEAR MAYAGUEZ
3-52
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3.2.4.4 Preserves and Reserves
Critical Wildlife Habitats along the Mayaguez coast include the Sabanetas
Swamp, about 5 nmi north, and Pta. Guanajibo, about 4 nmi southwest of the
Port (Figure 3-25).
Other areas designated as special planning areas by the Puerto Rico
Office of Coastal Zone Management (U.S. DOC 1978) include the Tourmaline Reefs
Reserve, about 11 nmi southwest of the port areas, and the Joyuda Mangrove
Reserve, about 5 miles southward along the coast (see Figure 3-24).
3.2.4.5 Threatened and Endangered Species
Threatened and endangered marine species in Puerto Rico include several
species of sea turtle and the brown pelican (see species list in Section
3.1.4.4). The Cabo Rojo region, about 7 to 15 miles south of Mayaguez, is an
important sea turtle habitat and nesting area.
No data were obtained on the frequency of occurrence or population
density of brown pelicans near Mayaguez. Boqueron State Forest, 13 to 14
miles south of Mayaguez, supports large numbers of pelicans (U.S. DOC 1978).
A list of threatened and endangered species identified in the Mayaguez
study area is presented in Table 3-6.
3.2.5 Recreational Areas
The recreational areas within a 15-mile radius of Mayaguez include
several heavily used bathing beaches (Puerto Rico Tourism Company 1983) and
one publicly maintained beach at AJiasco, due east of the interim site (Figure
3-25).
Other popular swimming areas are located at Playa Grande, approximately
2 nmi east of the interim site and a little further north, near Rincon.
Popular Rincon area beaches such as Punta Higuero are 5 to 6 nmi north of the
interim and alternate sites. Punta Higuero, 2 miles north of Rincon, is
especially popular for surfing.
3-53
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67°30'
67°20'
67°10'
18
25
18
20
18
15'
18
10'
18l
05'
18
00'
*
•lOOfm'
LEGEND
¦ Public Beaches
- Other Beaches
- Marinas
V.V.V - Wildlife Areas
• » * •
- Commonwealth Forests
¦fr " Wrecks
* Diving and Spearflshing
- Surfing Areas
Nautical Mllaa
(TTTTT1
as %
s
Sabanetas
Swamp
|18°
25'
118"
20"
118°
15'
18
10*
18°
05'
18°
00'
67°30'
67°20'
67°10'
FIGURE 3-25. RECREATIONAL AREAS, PRESERVES AND SHIPWRECKS NEAR MAYAGUEZ
3-54
-------
The large number of coral reefs inshore and south of the interim site are
likely recreational sites for scuba, snorkeling, and recreational fishing. No
information was found to indicate how frequently these sites are used.
3.2.6 Shipping Lanes
There are no formally established shipping lanes for Puerto Rican ports
and harbors. A two-year study conducted by the Seventh Coast Guard District
(46 FR 48376, October 1, 1981) determined that such lanes were not warranted
by the movements of vessel traffic near the island.
3.2.7 Mineral Resources
Quartz sand and metallic mineral deposits occur in the offshore portions
of the Mayaguez ZSF. A large quartz sand deposit occurs in the western half
of the Mayaguez ZSF (Cox and Briggs 1973). There are no known oil and gas
deposits or important concentrations of magnetite sands or mineral resources
in the study area (Guillou and Glass 1957; Alonso 1983; Cox and Briggs 1973;
Schneidermann et al. 1976). A salt-producing solar evaporator is located in
southwestern Puerto Rico about 15 nmi south of Mayaguez (White and Tuchman
1982).
3.2.8 Shipwrecks or Other Features of Historical or Cultural Importance
One shipwreck is immediately adjacent to the Mayaguez interim site
(Figure 3-25, University of Puerto Rico 1974). No wrecks have been identified
at or near any of the Alternate Sites. No other features of historical or
cultural importance have been identified in the Mayaguez ZSF.
3.2.9 Fisheries
A large part of the Puerto Rican commercial fishing fleet consists of
small boats fishing for coral-reef associated species on the islandic shelf.
The west coast is the most productive fishing region of the island, with
48 percent of the total landings between October 1982 and July 1983 (Caribbean
Fishery Management Council 1984). Most of the west coast harvest is taken on
the broad shelf area to the south of Mayaguez. The principal fishermen's
cooperative organization for this area, in the municipality of Cabo Roja, is
typically responsible for over 40 percent of Puerto Rico's total annual catch.
3-55
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Four large reefs lying just offshore of Mayaguez are commonly used by
local fishermen (Figure 3-24). The interim site is less than 1 nrai to the
northwest of the most seaward of these reefs. Heavy fishing also occurs about
9 nmi southwest of Mayaguez, around the Tourmaline reef, and further south
around the Las Coronas reefs.
3.3 CHARACTERIZATION OF THE AFFECTED ENVIRONMENT FOR PONCE
3.3.1 Oceanographic and Climatologic Characteristics
3.3.1.1 Bathymetry
Bottom topography in the central south coast of Puerto Rico off Ponce is
characterized by a narrow shelf about 1 to 3 nmi wide (Figures 1-3 and 3-26a).
Distinct submarine canyons extend to the south arid southwest of Punta Verraco
and Punta Guayanilla. East of the interim and alternate disposal sites, the
shelf becomes very broad (4 to 10 nmi out to the 200-m isobath). Off the area
of Punta Cabullon and Punta Pastillo (Figure 3-26b) the shelf is particularly
shallow (<20 m) and relatively broad (6-7 nmi).
3.3.1.2 Climatology
The southern coast of Puerto Rico has a tropical-marine climate dominated
by persistent easterly trade winds. Air temperature and wind patterns vary
only slightly on a seasonal basis. Mean monthly air temperatures for Ponce
range from 25°C (February) to 28°C (August). Infrequently, tropical storms or
the remnants of a winter cold front interrupt the easterly trade winds. Mind
records indicate average speeds of 4-6 m/sec from the east-southeast about 40
percent of the time (COE 1975).
3.3.1.3 Hydrography
The waters of the Caribbean Sea south of Puerto Rico are characterized by
four distinct water masses: (1) Tropical Surface Water, (2) Subtropical
Underwater, (3) Antarctic Intermediate Water, and (4) Venezuelan Bottom Water.
Vertical temperature, salinity, and density profiles for the region are shown
in Figures 3-27, 3-28, and 3-29, respectively. The upper water mass, Tropical
3-56
-------
(a)
(b)
FIGURE 3-26. BATHEMETRIC PROFILES OFFSHORE FROM PUNTA CUCHARAS AND
PUNTA PASTILLO
3-57
-------
temperature #c
16 18 20 22 24 26 28
FIGURE 3-27. AVERAGED TEMPERATURE PROFILE, BY SEASON, OFF PUNTA
VERRACO, 1973 AND 1974
Source: Wood et al. 1975f.
3-58
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SALINITY %•
34 35 36 37
FIGURE 3-28. AVERAGED SALINITY PROFILE, BY SEASON, OFF PUNTA VERRACO,
1973 AND 1974
Source: Wood et al. 1975f.
3-59
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20
0
D
E
P
T
H
m
100
200-
300
DENSITY a;
22 24 26
28
4i 3
2|1
2\\ \
7^4
Wl *
PVE
\1
11 m
Winter
1 1
Spring
2 1
Summer
5 1
Fall
4 1
2'"3
14
» i
FIGUPE 3-29. AVERAGED WATER DENSITY PROFILES, BY SEASON, OFF PUNTA
VERRACO, 1973 AND 1974
Source: Wood et al. 1975f.
3-60
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Surface Water (TSW), extends to a pycnocline at approximately 75 m. In this
upper layer, temperatures range from 25 to 29°C and salinity from 33 to 36
°/oo. The Subtropical Underwater (SUW) extends below the pycnocline from
approximately 100 to 200 m, and is characterized by a relatively more saline,
cooler layer (20-25°C, 36.8-37.2 °/oo). Vertical mixing between the upper
layer and the SUW layer below the pycnocline is sharply restricted as a result
of the strong density gradients across that boundary resulting from the dif-
ferences in temperature and salinity. Information on the depths of water mass
boundaries in the Ponce area is given in more detail in Appendix F, Section 1.
The information is not very complete for this area, as little direct current
measurement has been done here. The data that are available have been incor-
porated into the model used to predict sediment transport patterns from the
potential disposal sites, the results of which are presented in Chapter 4.
The SUW layer is deeper (from 200 to 600 m) and gradually changes to cooler
water (20-70°C), with salinity ranging from 35-36.8 °/oo. Antarctic Inter-
mediate Water (AIW) at 600-800 m is cold water (6-7°C) with a constant
salinity (34.8 °/oo). Venezuelan Bottom Water, with temperatures of 4-5°C and
salinities of about 35 °/oo, is found below about 100 meters. Such depths are
reached along this steeply sloping coastline within 7 nmi of shore, 2 to 3 nrai
south of alternate sites 2 and 3 (Atwood et al. 1976).
3.3.1.4 Circulation
The dominant large-scale transport regime off the southern coast of
Puerto Rico is the warm Caribbean Current (26-29°C). This current flows in a
general westerly direction parallel to the coastline. At some times, a
counter current is observed close to shore along this coast, suggesting a
relatively small, transient bight (loop current) off the main westward flow
(Atwood et al. 1976). Comprehensive large-scale summaries of the region's
surface drift indicate that the surface velocity ranges from about 15 to 40
cm/sec in a westerly direction (Wust 1964; U.S. Naval Hydrographic Office
1972). Specific features of surface and subsurface flow in the Ponce region
are presented in Figures 3-30 and 3-31.
3-61
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66*50' 66*40* 66*30' 66°20'
FIGURE 3-30. SURFACE LAYER TRANSPORT, PONCE STUDY AREA
-------
66*50' 66*40' 66»30' 66*20'
FIGURE 3-31. SUBSURFACE AND NEAR-BOTTOM TRANSPORT, PONCE STUDY AREA
-------
Tidal and Diurnal Wind Influences
The tidal cycle near Ponce is mixed-diurnal. The diurnal tide moves from
east to west past Ponce and Punta Verraco with a tidal height range of about
20 _+ 15 cm (Wood et al. 1975f). Nearshore studies near Guayanilla and Punta
Verraco indicate that since the total tidal height range is small, wind-driven
circulation processes would be dominant over tidal effects in the region near
Ponce (Hernandez-Avila et al. 1979). When wind stress influences are removed
mean tidal velocities on the south coast of Puerto Rico are: Ebb tide (6
cm/sec, SSE), and flood tide (10 cm/sec, WNW) (Hernandez-Avila et al. 1979).
Continuous surface layer current measurements suggest that there is net
transport at speeds of 5-20 cm/sec toward the southwest (Punta Verraco, Punta
Guayanilla), with significant diurnal variation resulting from the land-sea
breeze effect (night speeds decreasing in relation to daytime speeds,
Hernandez-Avila et al. 1979).
Subsurface Transport
Deep water current reversals have been reported east of Ponce in the
vicinity of Punta Tuna (Oser and Freeman 1969; Burns and Car 1975). jn the
northern Caribbean Sea, Atwood et al. (1976) used dynamic height calculations
to infer deep-water flow reversals. Subsurface current profiles (made in
October over the 1000 m isobath at Station 41) offshore from the alternate
disposal sites clearly indicate flow reversals of from 250 to 500 m (U.S.
Naval Oceanographic Office 1972). Within depth layers of 140-250 m, flow is
cross-slope to the northeast at 8-9 cm/sec. In contrast, at about 500 m,
transport is to the west at about 5 cm/sec. The deep current measurement (5
cm/sec, 500 m) at Station 41 is consistent with the speed and direction (5
cm/sec, W) of geostrophic calculations along 67°00' W at 500 m using data from
October 1972 (Atwood et al. 1976).
3.3.2 Geologic and Geochemical Characteristics
The sediments at the Ponce interim and alternate sites are soft silts and
claya that are primarily derived from land-based sources. This section
describes the basement rock, seafloor characteristics, sediment textures, and
sediment mineralogy for sites in the Ponce ZSF.
3-64
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3.3.2.1 Surficial Geology
The southern coast of Puerto Rico is characterized by very permeable
limestones covered by a sediment layer of variable thickness (Morelock et al.
1977). Although few limestone outcrops occur, areas of consolidated sand and
consolidated gravel are relatively common. Many of these occur as hardened
offshore sand bars or low tide deposits (Guillou and Glass 1957). The most
common sediment type that overlies the limestone on the shelf is described as
a brown mud that is low in calcium carbonate. This mud deposit is bordered on
the east and west by calcareous sands and gravels (Schneidermann et al. 1976).
Near shore, the sands are lower in calcium carbonate. They consist of dark-
colored siliceous, volcanic sands and andesitic gravels (Guillou and Glass
1957; Kaye 1959).
Sediment from land sources comes principally from the Portugues and
Bucana Rivers that flow through Ponce. These rivers flood frequently and
deposit sediment and debris into the Port of Ponce (COE 1975). The sediment
from the rivers moves westward (Kaye 1959).
Flood control projects have been initiated by the COE and include re-
inforcement of river banks, installation of debris basins, and channelization
of some sections of the rivers (Dichiara, 1984). These efforts should reduce
the long-term sediment input to the waters south of Ponce.
3.3.2.2 Sea Floor Characteristics and Sediment Textures
Within the Ponce ZSF, soft bottom was encountered in 23 of 24 sediment
samples (Figure 3-32). At the interim and alternate sites, the bottom is soft
and consists of fine-grained sediments.
The 21 sediment samples collected in the Ponce ZSF were predominantly
silt, with an average of 60 to 65 percent silt, 20 to 25 percent clay, and
less than 15 percent sand.
Interim Site - Samples are more clayey and lesB silty than sediments from
the alternate sites. Clay contents ranged from 21 to 43 percent, silt was 56
to 68 percent, and sand was 1 to 10 percent. This site has a minimum depth of
3-65
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FIGURE 3-22. SEDIMENT SAMPLING POINTS AND IDENTIFIED SEA-FLOOR SEDIMENTS
IN PONCE ZSF
-------
about 150 m and slopes to the south to a depth of about 500 m. The average
degree of slope across the site is 14.5 percent.
Alternate Site 1 - sediments are clayey-silts, averaging about 60 percent
silt and 35 percent clay, with less than 10 percent sand. The minimum depth
is about 366 m, and the site slopes westward to a depth of over 500 m. The
degree of slope is about 8 percent.
Alternate Site 2 - Samples taken in and near this site are over 60 per-
cent silt, less than 10 percent sand, and about 20 percent clay. The depth
ranges from about 450 to about 650 m, and the slope averages 6 to 7 percent.
Alternate Site 3 - The sediments are also predominantly silt, with over
60 percent silt, 15 to 30 percent clay, and less than 10 percent sand. Depths
range from 475 to 600 m and the slope averages 5.5 to 6 percent.
3.3.2.3 Sediment Mineralogy
Most of the sediment within the Ponce ZSF is apparently land-derived
material that was discharged from rivers near Ponce (Schneidermann et al.
1976). The fluvial sediment moves westward along the coast and becomes mixed
with marine calcareous material (Kaye 1959; Guillou and Glass 1957).
The sand fraction near shore occurs in narrow beaches, and consists of
quartz sand and dark-colored andesitic gravel that is more cobbly east of
Ponce and more sandy west of Ponce (Kaye 1959; Guillou and Glass 1957). There
are occasional outcrops of consolidated aand (beach rock) or consolidated
gravel (Guillou and Glass 1957). Farther offshore, the sand fraction is
dominated by calcium carbonate. On the southern Puerto Rico shelf, the sand
fraction averages 70 to 85 percent calcium carbonate, which is derived from
mollusc shells, coral fragments and other biogenic sources (Schneidermann et
al. 1976).
The silt fraction contains very fine sands and organic materials. At
Ponce, large quantities of organic matter are discharged by two sewage treat-
3-67
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ment plants, a tuna processing plant, and several sources of untreated sewage
(COE 1975).
The clay fraction consists of clay minerals, amorphous silica, hydrous
oxides of iron and aluminum, and colloidal organic matter. All of these
materials exhibit some degree of cation exchange capacity, through which
nutrients or contaminants can be temporarily adsorbed by the sediments
(McCarthy 1977). No data were found describing the types and relative amounts
of clay minerals in sediments near Ponce.
3.3.3 Water Quality
Surface waters throughout the Ponce study area are clean, warm, oxygen
saturated and nutrient depleted. Below the surface mixed layer, oxygen
remains undepleted, and nutrient levels become very high. In summary, water
quality in the area of the interim and alternate sites is excellent, and is
typical of tropical open-ocean conditions.
3.3.3.1 Turbidity
Secchi disc depth readings taken from shallow (<15 m) nearshore waters,
less than 2 nmi offshore near Ponce and Guayanilla are presented in Figures
3-33 and 3-34. Secchi depths ranged from 1 to 24 m. The lower values, indi-
cative of turbid water, were from sites closest to shore, and higher values,
indicating greater clarity, were taken further from shore. Based on these
measurements it appears that the waters in the ZSF are optically clear and
contain little suspended material (EPA 1981).
3.3.3.2 Dissolved Oxygen
Dissolved oxygen concentrations are consistently at or near saturation
levels in surface waters (Wood et al. 1975e). Figure 3-35 presents the
average dissolved oxygen depth profiles by season at Punta Verraco, 11 miles
west of Ponce, for 1973 and 1974. There is little seasonal change in surface
dissolved oxygen concentration. Oxygen levels decrease slightly with depth,
but still remain high at lower depths (on the order of 4.5 ml/1). The highest
dissolved oxygen values were measured in winter. The lowest dissolved oxygen
3-68
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plava de ponce
24
16
Of
NAUT Ml
29
FIGURE 3-33. SECCHI DISK READINGS IN METERS FOR NEARSHORE WATERS NEAR
PONCE, SEPTEMBER 1971
Source: Puerto Rico Department of Public Works 1974
3-69
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-------
DISSOLVED OXYGEN ml/I
D
E
P
T
H
m
100
200
300
a
| ¦
4
1 :
•
i/p pA
a
m
\\ \\
¦
pve
Winter 1
\\ I
Spring 2
Summer 3
Foil 4
23
¦
FIGURE 3-35. AVERAGED DISSOLVED OXYGEN DEPTH PROFILES BY SEASON, AT
PUNTA VERRACO, 1973 AND 1974
Source: Wood et al. 1975f.
3-71
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values occurred at about 200 m in all seasons except spring, when they
occurred at about 160 m. The lowest single dissolved oxygen value was about
3.9 ml/1 at 200 m during the winter season.
3.3.3.3 Nutrients
Nutrient levels in the surface waters show little seasonality, reflecting
the relatively stable marine conditions associated with Puerto Rico's tropical
climate. Surface waters are low in phosphate, nitrate, and silicate. Concen-
trations of these nutrients increase with depth below the pycnocline.
Seasonal concentrations of reactive phosphate measured in the vicinity of
Punta Verraco are presented in Figure 3-36. Surface water concentrations are
very low (0.05 ug-at P/l) throughout the year. There is little seasonal
variation in phosphate levels. Phosphate values are generally low throughout
the upper mixed layer and through the pycnocline to about 200 m. Peak values
at the deepest point sampled were about 0.33 ug-at P/l. In winter the concen-
tration begins to increase at 100 m and reaches about 0.38 ug-at P/l at 300 m.
Seasonal concentrations of nitrate are presented in Figure 3-37. The
concentration of nitrate was less than 1 ug-at N/1 from the surface to about
75 m in the summer and to 35 m in the fall. Nitrate values between 30 and
125 m were higher in the fall than in the summer. Little seasonal difference
was found below 125 m. The concentration of nitrate increased with depth from
about 2 ug-at N/1 at 100 m to greater than 13 ug-at N/1 at 300 m.
Surface silica values are low. Studies off Ponce and off Guayanilla, 10
miles to the west (Puerto Rico Department of Public Works 1974), found silica
concentrations ranging from 0.03 to 0.10 mg/l in surface waters. No data on
subsurface silica concentrations were found for this area.
3.3.4 Biota
Species identified in the Ponce study area are included in the species
list presented in Table 3-5.
3-72
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REACTIVE PHOSPHATE pg-at. P/l
FIGURE 3-36. AVERAGED REACTIVE PHOSPHATE DEPTH PROFILES, BY SEASON,
AT PUNTA VERRACO, 1973 AND 1974
Source: Wood et al. 1975f.
3-73
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NITRATE pg-at. N/l
O 2 4 6 8 10 12 14 16
FIGURE 3-37. AVERAGED NITRATE DEPTH PROFILES FOR THE SUMMER AND FALL
SEASONS, AT PUNTA VERRACO, 1974
Source: Wood et al. 1975f.
3-74
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3.3.4.1 Benthic Invertebrates
Information presented in this section is based on analyses of the bio-
logical samples conducted on EPA's 1984 DMDS survey cruise in Puerto Rico (JRB
1984).
The benthic community at the proposed site was dominated by deposit feed-
ing organisms (primarily polychaetes) typical of the fine-grained sediments
occurring at the site. The number of taxa and number of individuals per taxon
were low for most samples, although the types of taxa were relatively dif-
ferent among samples suggesting a patchy distibution of many organisms. Six
potential station groups were observed based on the results of cluster
analysis, however, the groups did not correspond to any obvious trends in
sediment grain size distribution and were not indicative of any influence from
past dredged material disposal at the Ponce DMDS (Table 3-3).
The total number of individuals per sample (all taxa combined) at all
sampling locations off Ponce were also corespondingly low, with a mean of 87
and a range of 26 to 176 individuals. Only nine of the 357 total taxa
occurred in more than half of the samples, with only two taxa (the pelecypod
Vesicomya pilula and the rhynchocoels) occurring in more than 20 samples (24
and 23, respectively). Of these nine taxa, only four (V. pilula, the
sipunculid Golfingia tricocephala, pelecypods, and members of the polychaete
family Ampharetidae) were found in abundances greater than 10 individuals per
sample. These data indicate similar low numbers of individuals for most taxa,
but also suggest dissimilarity in the types of taxa occurring among different
samples.
Polychaetes were the most abundant benthic organisms in all locations off
Ponce (143 taxa), followed by crustaceans (98 taxa), molluscs (92 taxa, pri-
marily gastropods and pelecypods), 17 minor taxa (primarily sipunculids and
rhynchocoels), and echinoderms (17 taxa). The majority of the 357 total taxa
found in the region were deposit feeders typical of fine-grained sedimentary
environments such as that generally occurring at the proposed site. The
average number of taxa per sample (station and replicate) was relatively low
(38) ranging from 16 to 55 taxa. The number of individuals per sample for
3-75
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TTAXA SCNT SMNWVR PIELOU
GRAVEL
SAND
SILT
CLAY
FINES
0 . 03509
0 8566
29
0.04823
0 8038
29
0 . 00715
0 9707
29
-0.12220
0.5277
29
-0.04891
0.8011
29
0.05796
0.7651
29
-0.06403
0.7414
29
0.13340
0 4903
29
-0.09191
0.6354
29
0.06087
0 7538
29
0 .04627
0.8116
29
-0.10559
0.5857
29
0. 13970
0.4698
29
-0.00958
0.9007
29
0. 10229
0.5975
29
0.03420
0.8602
29
-0.18144
0.3462
29
0.20457
0.2871
29
0.04833
0.8034
29
0.17754
0.3569
29
OPFT
-0.
1 1098
.5816
27
-0.27236
0.1693
27
-0.25750
0. 1947
27
-0.30853
0.1174
27
Table 3-3 Correlation Matrix for Sediment Grain Size, Biological Parameters
and Station Depth from the March, 1984 EPA/JRB Survey Offshore of
Ponce, Puerto Rico. (Correlation coefficients are listed first with
significance levels listed second and the number of comparisons third).
TTAXA = total number of taxa, SCNT = total number of individuals
of all taxa, SHNWVR = Shannon - Weaver Diversity Index, PIELOU =
Pielou's Eveness Index.
3-76
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each taxon was also low, with the majority occurring in densities of only one
2
to three individuals per 0.065 m . The species having the highest density (30
2
individuals per 0.065 m ) was the pelecypod (a bivalve mollusc) Nuculana
sp., occurring in one replicate sample collected at the interim site. A high
density of pelecypods also occurred at a location about 7 km (4 nmi) southeast
of the proposed site, where one taxon had a density of 35 individuals per
2
0.065 m (however this taxon may comprise several species). The two stations
with high pelecypod densities were at approximately the same depth (370 m, or
1200 ft). The similarity in the bivalves present at the interim site and this
other similar-depth site where no disposal has occurred is in accordance with
the general lack of significant faunal differences between the Ponce interim
site and other similar sites in the region. This suggests that disposal at
the Ponce site in the past has resulted in deposition that did not make major
changes in the benthic ecology of the site, or did not result in substantial
deposition at the site. The latter is a reasonable possibility, given the
potential for dispersion by horizontal transport and mixing before deposition
can occur at deepwater sites such as this.
3.3.4.2 Coral Reefs
Small reefs occur in great abundance all along the south coast of Puerto
Rico, including the Ponce Study area (Almy and Carrion-Torres 1963). Coral
reefs important to fishing occur around Caja de Muertos Island and Berberia
Key (see Figure 3-38). Other commercially important reefs occur about 10 nmi
directly west along the coast, in the coastal waters just outside Guayanilla
Bay.
3.3.4.3 Mangrove Breeding and Nursery Areas
Mangrove swamps and estuaries are important nursery areas for commer-
cially valuable marine fish such as lady fish, pompano, and several varieties
of snapper (Austin 1971). Organically rich mangrove root systems not only
offer protection to juvenile fish, but also support the productivity of the
invertebrates and algae upon which many of them feed. There is extensive
mangrove growth near the Ponce study area, including large stretches of coast-
line near Guayanilla Bay and Guanica Harbor. Guayanilla, one of the largest
3-77
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'/// ~ Important Commercial
Fishing Areas
Important Sport
Fishing Areas
,~ ¦ Coral Reefs/Bottom
Areas
18
00'
17
55'
17"
50'
17
45'
17
40*
• • •
• • •
Nursery Areas
Nautical Miles
1 1 1 1
2 3 4 5
66°50'
66°30'
FIGURE 3-38. LIVING MARINE RESOURCES NEAR PONCE
-------
bays in southern Puerto Rico, is the closest to Ponce, lying approximately 8
miles westward along the coast (see Figure 3-38). The Yauco River drains into
this bay. A very high year-round population of portunid crabs (principally
Callinectes danae), provides an excellent food source for juvenile fish in
Guayanilla Bay.
3.3.4.4 Preserves and Reserves
Critical wildlife habitats in the Ponce study area include the Guanica
Forest Reserve about 12 nrai west of Ponce, and Punta Cabullones, 2 to 3 nmi to
the east. In addition, the Caja de Muertos Reserve, composed of Caja de
Muertos Islands and nearby Berberia Key, lies from 4 to 9 nmi east of alter-
nate site 1 and 3 (see Figure 3-39).
3.3.4.5 Threatened and Endangered Species
Threatened and endangered marine species in Puerto Rico include several
sea turtles and the brown pelican. Caja de Muertos Island, a natural reserve
4 nmi east of Alternate Site 3, is a nesting ground for sea turtles (DOC 1978,
and Figure 3-39). Very high densities of turtles occur on beaches of this
island.
It is not known to what extent pelicans inhabit the Ponce coastal area.
If they are present, they will be primarily in the nearshore areas of the
mainland and perhaps at Caja de Muertos. Pelicans typically remain close to
land, making only short trips over offshore waters, except when migrating.
They feed principally along the coast where the small fish they eat are
relatively abundant.
A list of threatened and endangered species identified in the Ponce study
area is presented in Table 3-6.
3.3.5 Recreational Areas
There are several beach areas to the west of Ponce (Figure 3-39). The
closest of these is just past Punta Cucharas, approximately 4 nmi from the
interim site. Another is located further to the west, off Punta Verraco and
two others are located within the Guanica Forest area.
3-79
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66°50' 66°40' 66°30'
FIGURE 3-39. RECREATIONAL AREAS, PRESERVES AND SHIPWRECKS NEAR PONCE
-------
There is a marina east of Ponce near Punta Cabullones. This facility
supports some of the extensive commercial fishing that occurs to the east and
west. It is also used as a base for recreational boating and fishing.
3.3.6 Shipping Lanes
There are no formally established shipping lanes for Puerto Rican ports
and harbors. A 2-year study conducted by the Seventh Coast Guard District (46
FR 48376, October 1, 1981) determined that such lanes were not warranted by
the amount and direction of vessel traffic near the island.
3.3.7 Mineral Resources
There are no known deposits of oil, gas, high-magnetite sands, or quartz
sands at any of the potential disposal sites or near the Ponce ZSF (Alonso
1983; Guillou and Glass 1956; Schneidermann et al. 1976). There is no solar
salt production in this area (White and Tuchman 1982).
3.3.8 Shipwrecks or Other Features of Historical or Cultural Importance
There are no shipwrecks at or immediately adjacent to any of the poten-
tial disposal sites for Ponce. The only known wrecks are in the shore zone,
over 3 nmi away from the interim site (Figure 3-39, University of Puerto Rico
1974). No other features of historical or cultural importance have been
identified in the Ponce ZSF.
3.3.9 Fisheries
The bulk of the Puerto Rican fishing industry consists of small boats
fishing for reef-associated species over the shelf. Records of fish landings
for October 1982 through July 1983 show the south coast harvest as the second
largest portion of the island's fish and shellfish landings (1.2 x 10^ lbs.,
25 percent of the total, Caribbean Fishery Management Council 1984) .
Commercial fishing activities of municipalities throughout the central
south coast are concentrated on the shelf, particularly the broad area just
east of the Ponce ZSF extending eastward along the shelf boundary for 10 to 15
miles (Figure 3-38). Commercial species commonly landed from this area
3-81
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include grunts, porgies, goatfish, mackerel, groupers, snappers, squirrel
fish, ballyhoo, barracuda, triggerfish, parrot fish, spiny lobster, sea
turtles, conch, and octopus. Major sport fishes include tarpon, king
mackerel, and various sharks (COE 1975).
3.4 CHARACTERIZATION OF THE AFFECTED ENVIRONMENT FOR YABUCOA
3.4.1 Oceanographic Characteristics
3.4.1.1 Bathymetry
Bottom topography of the southeastern coast of Puerto Rico is charac-
terized by a pronounced change from north to south. To the north of Yabucoa
there is a broad shallow shelf (Figure 1-4). The sea floor then drops off
rapidly (from less than 30 m down to 800 m or more) just south of Punta
Guyanes and Vieques Island. The insular shelf to the south, at Punta Yeguas,
and continuing to the west, past Punta Tuna, is very narrow (2 to 3 nmi) with
the slope dropping off sharply to depths of 800-1000 m over distances of less
than 2 km from the coast (Figure 3-40 and 1-4). Bottom depths then slope
gently (15° slope) from south of Yabucoa to the 2000 m depth of the Virgin
Islands Trough about 40 km to the south-southeast. A prominent topographic
feature is Grappler Bank ( 80 m depth), about 18 nmi southwest of the interim
disposal site.
3.4.1.2 Climatology
This area is characterized by a tropical-marine climate with persistent
easterly trade winds. The monthly mean air temperature varies only slightly
(1.5°C) from the annual mean of 27°C (Atwood et al. 1976). Seasonal changes
result in a transition in the predominant wind direction from north-northeast
in winter to east in the summer. Wind observations indicate average speeds of
4.5-5 m/sec in autumn, 6-8 m/sec in summer and stronger northerly winds of
greater than 14 m/sec occurring occasionally (about a 2% frequency) during the
winter and spring (Atwood et al. 1976).
Wave regimes in the coastal region of southeastern Puerto Rico are
strongly influenced by the prevailing wind patterns. Frequency statistics,
3-82
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I 1 1 1 I '
0 2 4 6 8 10 KM.
FIGURE 3-40. BATHYMETRIC PROFILES OFFSHORE FROM PUNTA TUNA (A)
AND PUNTA YEGUAS (B)
Source: Atwood et al. 1976.
3-83
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compiled by the U.S. Naval Weather Service Command (1974), have been summar-
ized by Hernandez-Avila et al. (1979) and Atwood et al. (1976). Average wave
height is 1 m with an average wave period of 5.9 sec. Wave heights range from
0.3-1.4 m with wave periods less than 6 sec during 79% of the year. The rela-
tionship of wave height to wind speed for the Vieques/Yabucoa area indicates
that for a typical summer/autumn windspeed of 4-8 m/sec, the corresponding
wave height is about 0.3-1.2 m.
Hurricanes occur in the Caribbean, principally between June and November.
Bret Schneider (1977) has estimated that the "most probable" hurricanes will
have windspeeds of greater than 41 m/sec, with waves averaging over 7 m in
height.
3.4.1.3 Hydrography
The waters of the Caribbean Sea off southeastern Puerto Rico are charac-
terized by four distinct water masses: (1) Tropical Surface Water; (2) Sub-
tropical Underwater; (3) Antarctic Intermediate Water and (4) Venezuelan
Bottom Water. Temperature, salinity and density profiles from the region are
shown in Figures 3-41, 3-42 and 3-43 respectively. The upper-layer water
mass, Tropical Surface Water (TSW), extends to a depth of 75 m with tempera-
ture ranging from 25°-29° C and salinity varying from 33-36°/oo. The Sub-
tropical Underwater (SUW) below the pycnocline at about 100 to 200 m is
characterized by a more constant density (temperature of 20-25°C, salinity of
26.8-37.2°/oo) than the TSW layer. The strong density differences between the
two layers results in minimum vertical mixing between them. Between 200 and
600 m, temperatures drop from 20 to 7°C and salinity ranges from 36.8 to 35
°/oo. Antarctic Intermediate Water (AIW) at 600 to 800 m is characterized by
cold temperatures (6-7°C) and salinity of 34.8%. Below this layer, North
Atlantic Deep Water and Venezuelan Bottom Water (4-5eC, 35°/oo salinity)
extend from 800 m to the bottom. (Atwood et al. 1976; Hernandez-Avila et al.
1979; Lopez and Tilly 1983).
Inspection of seasonal density profiles off Cabo Mala Pascua about 9
miles southwest of Yabucoa suggests a pycnocline depth of about 50-75 m in the
summer/autumn and about 100 m in the winter/spring. The most probable
seasonal depths are 100 m (February-March) and 40-50 m (September-November).
3-84
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TEMPERATURE CO
1
i
16 18 20 22 24 26 28
0 | I l l l l I I I I I 1 I
100
z
H
I 200
300
> DflPWATH SITi
CAIO MALA PASCUA
MJNTA VEMACO
¦ ¦ ¦ ' I I I I I I—I L.
SPRING TEMPERATURE
TEMPERATURE CO
.16 18 20 22 24 26 28
0 r-i—i—i—i i i i i—i—i—ft
J
J
s
Si 200
Q
300
CAIO MALA PASCUA
— SPtING
SUMMCI
— — — MU
WINTIt
J L-J * iii i i i i
SEASONAL TEMPERATURE
FIGURE 3-41. SPRING AND SEASONAL TEMPERATURE PROFILE FOR DEEPWATER
SITE, CAB0 MALA PASCUA AND PUNTA VERRAC0
Source: EG&G 1978.
3-85
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SALINITY (O/oo)
34 35 36 37
—
i i i i i n u i—i—i—i
¦
il
-
"
-
-
¦
ockpwatii srn fj
¦
CAIO MALA PASCUA jf
—PUNTA VIBBACO A
"
NO DATA hj
I 1 1 1
-
SPRING SALINITY
SALINITY (O/oo)
Figure 3-42. SPRING AND SEASONAL SALINITY PROFILE FOR DEEPWATER
SITE, CABO MALA PASCUA AND PUNTA VERRACO
Source: EG&G 1978.
3-86
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100
D
E
P
T
H
m
200-
DENSITY Ot
22 24 26
300-
FIGURE 3-43. AVERAGED WATER DENSITY PROFILE, BY SEASON, OFFSHORE
OF CABO MALA PASCUA, 1973 AND 1974
Source: Wood et al. 1975e.
3-87
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3.4.1.4 Circulation
The dominant large scale transport regime off the south coast of Puerto
Rico is the warm (26-29°C) Caribbean Current. This current, driven by the
predominant northeasterly trade winds of low latitudes, flows in a westerly
direction. Comprehensive summaries of the surface-layer net transport of the
Caribbean are presented in Wiist (1964) and Lee et al. (1978). In general,
surface drift near Yabucoa is on the order of 18-40 cm/sec towards the west
and southwest. Surface and subsurface current patterns in Yabucoa are
particularly complex, possibly due to "island effects", which are typically
observed when a major current is deflected by the corner of a large island
(Lopez and Tilly 1983).
Tidal and Diurnal Wind Influences
The tidal cycle near Yabucoa is a mixed-diurnal cycle. The diurnal tide
moves from east to west past Yabucoa and Cabo Mala Pascua, with a tidal height
range of about 25 15 cm (Wood et al. 1975).
Over the shelf region of the Vieques Passage, between the east coast and
the island of Vieques, tidal forcing is a dominant component of the circula-
tion. Tidal transport tends to flow parallel to the coastline. Ebb tide flow
is towards the northeast and east at speeds of 20-36 cm/s while flood tide
flow is towards the southwest at 20-30 cm/s (Figure 3-44). Maximum tidal
excursions in the passage are about 9 km (EPA 1981).
Northeast of the interim site, surface tidal currents are about 20 cm/s
with net transport to the northwest, while subsurface tidal currents are about
7 cm/s or less with net flow to the south-southeast (EPA, 1981). Surface cir-
culation in deep water is dominated by wind driven currents. Offshore surface
transport is generally towards the west-southwest at speeds of 5-40 cm/s (Wust
1964; Burns and Qar 1975; Lee et al. 1978). Within the nearshore region of
the narrow continental shelf, surface flow ranges from 5-25 cm/s towards the
southwest and the northeast, parallel to the coastline. The open ocean
westerly flow appears to separate into two flows near the southeast comer of
Puerto Rico with transport towards the southwest (as at Cabo Mala Pascua) and
towards the northeast (as at Punta Tuna and Punta Yeguas) (Wood et al. 1975d).
3-88
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66*00*
65*50'
18*10* -
18*00' -
- 18*10'
- 18*00'
66*00'
65*50'
65*40'
FIGURE 3-44. SURFACE LAYER TRANSPORT, YABUCOA STUDY AREA
-------
Subsurface Transport
Few current meter measurements have been made in the region at interme-
diate depths where potential disposal sites for Yabucoa are located. The few
deepwater measurements (1000-2000 m) offshore of Yabucoa and Punta Tuna do
provide some information on subsurface circulation features in the vicinity,
which allows some extrapolation of what the general subsurface circulation
patterns at the sites may be (Figure 3-45).
Available data from deepwater current-meter arrays suggest the presence
of sub-surface currents that follow bottom isobaths within the depth layer
of 100-300 m (Burns and Car 1975; Oser and Freeman 1968). At 600 m the
cross-slope transport in the vicinity of Alternate Sites 2 and 3 is to the
northeast, towards Vieques Island (Oser and Freeman 1968).
Based on a series of hydrographic sections off Punta Tuna and Punta
Yeguas in 1980, Lopez and Tilly (1983) demonstrated the presence of eddies on
the order of 5 to 15 nmi (10-25 km) in radius, located about 9 to 15 nmi south
and southwest of the interim and alternate disposal sites (Figure 3-45). In
addition to the anti-cyclonic (counter-clockwise) eddy shown, cyclonic (clock-
wise) eddies were also observed south of Jobos Bay to the west of the Yabucoa
region. The eddies, coherent to depths of 100-400 m below the upper mixed
layer, are indicative of the high potential in this area southeast of Puerto
Rico for flow in directions opposite to the large-scale general circulation
patterns. In general, subsurface transport processes are considerably more
complex and less well understood than surface flow, and are strongly
influenced by the steep bottom topography of the region. Subsurface currents
offshore vary with depth, and with flow reversals and large-scale eddies.
Typical flow within nearshore waters 100-300 m deep was usually to the south-
west or west, parallel to isobaths, at speeds ranging from 5-25 cm/sec.
3.4.2 Geologic and Geochemical Characteristics
The sediments at the Yabucoa interim and alternate sites are silty but
somewhat coarser than the sediments near the other three harbors. The geology
and sea floor characteristics near this harbor also differ from that of the
other harbors. This section describes the geology, sea floor characteristics,
sediment textures and sediment mineralogy in the Yabucoa ZSF.
3-90
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66*00'
3
65°50'
65*40'
18*10*
18*00'
SUBSURFACE AND NEAR-BOTTOM TRANSPORT (cm/s)
(DEPTHS OF OBSERVATIONS IN METERS)
(T) PUERTO RICO DPW (1974) 6/71, 5/71, 1/72
(2) ATWOOD el al. (1976) 9/75
(3) WOOD el al. (1975) 5/71. 6/71, 1/72, 11/72
® OSTERICHER (1967)
(§) WUST (1964)
(6) LOPEZ AND LILLY (1983) 1/80, 3/80,
11/80, 7/80, 9/80, 1/81, 10/81, 2/81
(7) BURNS AND CAR (1975) 3/67, 12/68
(f) LEE el al. (1978)
© OSER AND FREEMAN (1969) 12/68
EPA (1981) EIS 4/78
,
// ^
/
4
VIEQUES
*•100 fm ••••
500 fm
/ 600m
SUBSURFACE EDDIKS KNMOOm
810m
¦6^
© 220m
c
NAUTICAL MILES
I 1 1 1 1 1
X
T
18°10'
18*00*
66*00*
65*50*
65*40'
FIGURE 3-45. SUBSURFACE AND NEAR-BOTTOM TRANSPORT, YABUC0A STUDY AREA
-------
3.4.2.1 Surficial Geology
The city of Yabucoa is in a broad alluvial valley bounded by high
granitic mountains. The bedrock types in this area are granites and diorites
(Meyerhoff 1932). These types of rocks v>eather slowly to produce soils that
are very sandy, with low clay contents. Eroded soils are carried by the
Guayanes and Santiago Rivers and discharged into the Vieques Passage at the
Port of Yabucoa.
The rock types at the interim and alternate sites can be extrapolated
from the rock types of Eastern Puerto Rico and Vieques Island. The rock types
beneath the sediments in the Yabucoa ZSF may include granite and diorite, or
sandstones and siltstones that are comprised of volcanic sediments (e.g. lava,
tuff, and breccia). Small limestone lenses or areas of hydrothermally altered
rock may also occur. These rock types are extrapolated from a hydrogeological
map of Puerto Rico by Briggs and Akers (1965).
3.4.2.2 Sea Floor Characteristics and Sediment Textures
At the 24 stations surveyed in the Yabucoa ZSF, five had hard bottoms.
These hard-bottom areas corresponded to steep portions of the shelf edge, as
shown in Figure 3-46.
The sediment samples in the Yabucoa ZSF were predominantly silt; the
average sand content was 25 to 30 percent. Silt and clay averaged 50 to 60
percent and 15 to 20 percent, respectively.
Interim Site - This site slopes steeply to the south. The southern portion is
extremely steep and is devoid of sediments (EPA 1981). The sediments in the
central and northern portions are sandy (50-80 percent sand), with 20 to 40
percent silt and less than 15 percent clay. The slope in the northern section
is about 6 percent. The depth ranges from less than 180 m in the northern
half to over 650 meters in the southern half.
Alternate Site 1 - The sediments are finer grained than at the interim
site. The average sediment composition is 50 to 60 percent silt, 20 percent
clay and 15 to 30 percent sand. Depths range from about 700 to over 1000 m.
The slope at this site averages 15 percent.
3-92
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temr ts'sv
FIGURE 3-46. SEDIMENT SAMPLING POINTS AND IDENTIFIED SEA-FLOOR SEDIMENTS
IN YABUCOA ZSF
-------
Alternate Site 2 - Sediments contain less than 10 to 40 percent sand.
The higher sand contents are found in the shallower areas and the lower sand
contents are found in the deeper areas. This is likely due to the higher
current velocities in the shallower zones. Depths at the site range from
about 780 to over 1100 m. The slope averages 9 percent.
Alternate Site 3 - Samples taken in and near this site are silty, con-
taining from 50 to 75 percent silt, 10 to 45 percent sand and 10 to 20 percent
clay. As with sediments at alternate site 2, the sandier sediments at this
site are found in the shallower waters. Depths range from about 230 to about
800 m. Slopes range from 22 to 28 percent.
3.4.2.3 Sediment Mineralogy
The sediments in the shallower portions of the Yabucoa ZSF are very
coarse grained and are predominantly marine in origin. The shallow, high
energy areas contain shell fragments with less than 2 percent noncalcareous
material (Schneidermann et al. 1976; Bowman et al. 1975). The deeper portions
of the Yabucoa ZSF accumulate fine-grained, land-derived and marine materials.
The deepest areas contain the more clayey sediments and the areas having
intermediate depths have siltier sediments (1984 survey cruise). Because the
sediments are derived from both marine and land sources, the sand fraction is
likely to contain predominantly calcareous materials, with only minor amounts
of quartz and other minerals that are resistant to weathering. The sand frac-
tion is predominantly calcareous materials on most of the outer shelf of
Puerto Rico (Schneidermann et al. 1976).
The silt fraction is very-fine material, and contains very small amounts
of organic materials. Samples collected in the shallow, high energy areas
north of the Yabucoa ZSF contained less than 1 percent organic material. Most
of this material was plant debris (Bowman et al. 1975). The mineralogy of the
clay fraction is likely to be highly variable. Data on the types of clay
minerals present were not available.
3-94
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3.4.3 Water Quality
Surface waters throughout the Yabucoa ZSF are clean, warm, oxygen satur-
ated and nutrient depleted. Below the surface mixed layer, oxygen remains
undepleted, and nutrient levels become very high. In summary, water quality
in the area of the interim and alternate sites is excellent, and is typical of
tropical open-ocean conditions.
3.4.3.1 Turbidity
Secchi disc depth readings taken from shallow (<15 m) nearshore waters
(less than 2 nmi offshore) near Yabucoa and Humacao, 8-9 nmi north of Yabucoa
Harbor, ranged from 3-42 m (Puerto Rico Department of Public Works 1974). The
lower values, indicating turbid water, were from sites closest to shore and
higher values, indicating greater clarity, were further from shore. Concen-
trations of suspended material in the area of the Vieques deep water disposal
site (in the ZSF) are presented in Figure 3-47 (EG&G 1978). Values range from
0.2-5.7 mg/1 above the pycnocline to 0.1-2.5 mg/1 just below the pycnocline,
and 0-0.48 mg/1 in the near bottom waters. All of the turbidity readings were
well below 1.0 Nephelometric Turbidity Units (NTU), which indicates that water
in this area is optically clear and contains little suspended material.
3.4.3.2 Dissolved Oxygen
Dissolved oxygen concentrations are consistently at or near saturation
levels in the surface waters near Yabucoa (EG&G 1978; Atwood 1976). Figure
3-48 presents the average dissolved oxygen depth profile by season for Cabo
Mala Pascua, about 10 nmi southwest of Yabucoa Harbor. Little change in dis-
solved oxygen concentration by season can be observed. The area is charac-
terized by an oxygen-rich, warm surface layer about 75 m deep. The greatest
average dissolved oxygen values were measured in the winter. The dissolved
oxygen minimum occurred at about 200 m, with slightly shallower depths in the
spring and slightly deeper in the summer. The dissolved oxygen content in the
mid to bottom waters dropped to a minimum of 4.1 ml/1 in the spring. The
majority of the dissolved oxygen values were greater than 4.5 ml/1. A similar
profile showing little seasonal variation was measured off Punta Tuna, about 5
nmi southwest of Yabucoa (Atwood et al. 1976).
3-95
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FIGURE 3-48. AVERAGED DISSOLVED OXYGEN DEPTH PROFILES, BY SEASON, AT
CABO MALA PASCUA, 1973 AND 1974
Source: Wood et al. 1975e.
3-97
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3.4.3.3 Nutrients
Nutrient levels in surface waters exhibit little seasonality, reflecting
the relatively stable marine conditions associated with Puerto Rico's tropical
climate. Surface waters are low in nutrients (phosphate, nitrate and sili-
cate). Concentrations of these major nutrients increase with depth below the
pycnocline.
Seasonal concentrations of reactive phosphate measured near Cabo Mala
Pascua are presented in Figure 3-49 (Wood et al. 1975d). Surface concen-
trations are generally low (0.05 ug-at P/l) throughout the year. Phosphate
values remain low down to nearly 200 m and then increase to 0.30 ug-at P/l at
the deepest point sampled (Atwood et al. 1976). Phosphate profiles in the
vicinity of Punta Tuna exhibited a similar pattern. Values ranged from 0.0-
0.25 ug-at P/l at the surface and increased to 1.7-1.9 ug-at P/l at 1000 m
(Atwood et al. 1976; DOE/EA-0062). There are slight seasonal variations in
phosphate concentration.
Summer and fall concentrations of nitrate measured near Cabo Mala Pascua
are presented in Figure 3-50 (Wood et al., 1975d). Surface nitrate concentra-
tions were low in the upper mixed layer. At 150 m nitrate concentrations
began to increase to 10.5 ug-at N/1 in the summer and 20 ug-at N/1 in the
fall.
Similar nitrate profiles have been observed elsewhere in the Yabucoa
study area. Nitrate concentrations around Punta Tuna increased from 1 micro-
molar at the surface to 26 micromolar at 1000 m (DOE).
Surface silica values are low. Studies in the vicinity of Yabucoa and
Humacao (Puerto Rico Department of Public Works 1974) measured silica con-
centrations ranging from 0.09-0.6 mg/1 in surface waters. Atwood et al.
(1976) measured silicate concentrations in subsurface waters in the vicinity
of Punta Tuna (Figure 3-51). Silicate concentrations in the upper mixed layer
ranged from 1-3 ug-at S/l. Silica concentrations began to increase at 200 m
and reached 27 ug-at S/l at the deepest point sampled (1000 m). The vertical
distribution pattern of silicate did not vary substantially throughout the
study.
3-98
-------
0
100
D
E
P
T
H
m
200
300
FIGURE 3-49. AVERAGED REACTIVE PHOSPHATE DEPTH PROFILES, BY SEASON.
AT CABO MALA PASCUA, 1973 AND 1974
Source: Wood et al. 1975e.
3-99
-------
NITRATE yg-at. Is|/I
0 2 4 6 8 10 12 14 16 18 20
FIGURE 3-50. AVERAGED NITRATE DEPTH PROFILES FOR THE SUMMER AND FALL
SEASONS, AT CABO MALA PASCUA, 1974
Source: Wood et al. 1975e.
3-100
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3-101
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3.4.4 Biota
Species identified in the Yabucoa study area are included in the species
list presented in Table 3-5.
3.4.4.1 Benthic Invertebrates
Information presented in this section is based on analyses of the bio-
logical samples conducted on EPA's 1984 DMDS survey cruise in Puerto Rico (JRB
1984).
The benthic community in the Yabucoa study area is dominated by deposit
feeding organisms (primarily polychaetes) typical of fine-grained sediments
occurring at the disposal site. However, increased numbers of filter feeders
were present, reflecting the relatively heterogenous sedimentary environment
at the Yabucoa site. Two station groups were distinguished based on cluster
analysis. Both groups contain stations representing a broad range of survey
depths (600 to 3300 feet), and are characterized by extremely variable values
for diversity and evenness (Table 3-4).
Polychaetes (185 taxa) were dominant in the Yabucoa study area, followed
by crustaceans (90 taxa), molluscs (57 taxa, primarily gastropods and
pelecypods), 16 minor taxa (primarily sipunculids), and echinoderms (9 taxa).
The majority of the 357 total taxa were deposit feeders, however, filter
feeders, carnivores and herbivores were also common as would be expected from
the relatively heterogenous sedimentary environment. The mean number of taxa
per sample (station and replicate) was relatively low (40) and extremely
variable, ranging from 12 to 77. The total number of individuals per sample
(all taxa combined) was moderate (mean of 87), but was highly variable, with a
range of 18 to 615. The number of individuals per sample fdr each taxon was
low, with the majority of taxa occurring at densities of only one to four
2
individuals per 0.065m .
3.4.4.2 Coral Reefs
Reefs are well developed along the east coast of Puerto Rico, with excep-
tional development found in the fringing reefs around La Cordillera, about 40
3-102
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TTAXA
SCNT
SHNWVR
PIELOU
GRAVEL
SAND
SI LT
CLAY
FINES
DPFT
0.33560
0.1601
19
0 40724
0.0835
19
-0.45420
0.0508
19
-0.30164
0.2095
19
-0.42693
0.0683
19
-0.51951
0 0111
23
0.56375
0.0119
19
0.62189
0.0045
19
-0.66231
0.0020
19
-0.52923
0.0198
19
-0.65298
0.0024
19
-0.10736
0.6258
23
-0.40884
0.0822
19
-0.29218
0.2248
19
0.30607
0.2025
19
0.30079
0.2108
19
0.32089
0.1804
19
-0.32599
0. 1290
23
-0.51382
0.0244
19
-0.47037
0.0421
19
0 . 49415
0.0315
19
0.43724
0.0612
19
0.50161
0.0287
19
-0.17133
0.4344
23
Table 3-4 Correlation Matrix for Sediment Grain Size, Biological Parameters
and Station Depth from the March, 1984 EPA/JRB Survey Offshore of
Yabucoa , Puerto Rico. (Correlation coefficients are listed first
with significance levels listed second and the number of comparisons
third). TTAXA ¦ total number of taxa, SCNT * total number of
individuals of all taxa, SHNWVR ¦ Shannon - Weaver Diversity
Index, PIELOU ¦ Pielou's Eveness Index.
3-103
-------
miles northeast along the coastline from Yabucoa (Almy and Carrion-Torres
1963). As shown in Figure 3-52, one reef is located about 4 nrai northeast of
Punta Guayanes, considerably inshore of the sites under consideration in this
EIS. No corals have been positively identified at any of the alternate sites
or the interim site. However, an unspecified sinuous ridge that has
morphology similar to a coral reef is identified by the NOAA topographic chart
for the region (NOAA 1980) as passing through the central northern, shallow
section of the Yabucoa interim site. At that point the depth of the sea floor
is typically about 36 tn (20 fathoms), with the narrow ridge extending upwards
to a depth below the surface of only 16 m (9 fathoms).
3.4.4.3 Mangrove Breeding and Nursery Areas
No areas of special importance as breeding or nursery areas for juvenile
fish have been described for areas near Yabucoa. Numerous fish species are
especially abundant in the shallow shelf area immediately to the north of the
Yabucoa study area. A literature search did not produce evidence of specific
coastal breeding areas being used preferentially by local fish species. How-
ever, all shelf areas are spawning locations, with perhaps some preference
shown by certain species for spawning near the shelf edge (Colin 1983).
3.4.4.4 Preserves and Reserves
Critical wildlife habitats in the Yabucoa study area include the Ceiba
Forest Reserve, about 11-12 nmi northeast of the Port of Yabucoa and the
Humacao Swamp and Pterocarpus Forest Reserve, about 15 km (8 nmi) to the
northeast (Figure 3-53).
The Ceiba Forest Reserve is inhabited by manatees, an endangered species
that feeds in seagrass beds at the shoreline. There is also a large popula-
tion of the white-cheeked pintail, an endangered duck species. The Ceiba
Forest Reserve also contains the West Indian tree duck, which is on the
Commonwealth of Puerto Rico endangered species list. The heavily forested
Humacao Preserve contains the most extensive remaining tract of the rare
Pterocarpus officinalis.
3-104
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66°00'
65°40'
66°001
'/// " Important Commercial
Fishing Areas
- Important Sport
Fishing Areas
Coral Reefs/Bottom
Areas
Nursery Areas
65°50'
17
55'
Nautical Miles
T—r
3 4
17
50'
65°40'
FIGURE 3-52. LIVING MARINE RESOURCES NEAR YABUCOA
-------
66°00'
65°50"
65°40'
18"
10'
18
05'
18
00'
17
55'
17
50'
18
10'
18
05'
18
00'
17
55'
17
50'
FIGURE 3-53. RECREATIONAL AREAS, PRESERVES AND SHIPWRECKS NEAR YABUCOA
-------
3.4.4.5 Threatened and Endangered Species
Threatened and endangered marine species in Puerto Rico that may be
affected by dredged material disposal include several sea turtles and the
brown pelican. Vieques Island, 13 to 14 nmi east of Yabucoa and 5 nmi east of
alternate site 3, is a nesting ground for sea turtles. No regular sea turtle
habitats have been reported within 5 nmi of the proposed sites.
Any brown pelicans that live on the mainland shore or Vieques Island
would not be expected to frequent areas affected by disposal at any of the
sites; pelicans typically remain close to shore except for brief trips or
while migrating.
A list of threatened and endangered species identified in the Yabucoa
study area is presented in Table 3-6.
3.4.5 Recreational Areas
A number of recreational sites exist within a 15 mile radius of Yabucoa
including the Grappler Bank area, approximately 18 km (10 nmi) southeast of
the Port of Yabucoa, the site of a growing fishery. Another intensively used
sport fishing area is located in the southern and western nearshore waters of
Vieques Island (Figure 3-52).
In general, the east coast of Puerto Rico is most heavily used by
tourists around the resort towns of Humacao and Fajardo (Figure 3-53). Sport
fishermen and divers from Humacao travel from the resort area out to Vieques
Island. A major attraction is snorkeling and diving around the reefs found
along the shelf in this area (Figure 3-52).
Other recreational features of the area include a number of beaches and a
marina (see Figure 3-53). Sailing and windsurfing equipment is available out
of Humacao (Puerto Rico Tourism, CO. 1983).
3-107
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3.4.6 Shipping Lanes
There are no formally established shipping lanes for Puerto Rican ports
and harbors. A two-year study conducted by the Seventh Coast Guard District
(46 FR 48376, October 1, 1981) determined that such lanes were not warranted
by the amount and direction of vessel traffic near the island.
3.4.7 Mineral Resources
There are no oil or gas, magnetite, or other known mineral deposits in
the vicinity of the Yabucoa ZSF or any of the sites (Alanso 1983; Guillou and
Glass 1957; Cox and Briggs 1973). There are no solar salt producers along
this section of the Puerto Rico Coast (White and Tuchman 1982). A major
quartz sand source is located about 5 nmi to the north of the ZSF, beyond the
island of Vieques (Grove and Trumball 1978).
3.4.8 Shipwrecks or Other Features of Historical or Cultural Importance
There is one shipwreck 1 nmi south of the southern corner of the Yabucoa
interim site, and less than a mile southeast of alternate site 1 (Figure
3-53). All other shipwrecks reported in this area are on the shelf area two
or more nautical miles to the south of the ZSF (University of Puerto Rico
1974).
No other features of historical or cultural importance have been identi-
fied in the Yabucoa ZSF.
3.4.9 Fisheries
The bulk of the Puerto Rican fishing industry consists of small boats
fishing over the shelf. The east coast is third among the four coasts in
landings, with 8 x 10 pounds (about 17% of total Puerto Rican landings) for
the period October 1982-July 1983 (Caribbean Fishery Management Council,
4
1984). Of the east coast total, 6.6 x 10 pounds were reported from the
Yabucoa fishing district. This composed about 1.4 percent of the island's
total landings. Figure 3-52 shows coral reefs and fishing grounds in the
vicinity of Yabucoa. The wide shelf area northward from Yabucoa is fished
extensively. The narrow "sill-reef" zone southwards along the coast from
3-108
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Yabucoa is also important for fisheries in this area (Cole 1976). The
Grappler Bank (about 14 ntni southwest of the Port of Yabucoa) is an important
fishing area that lies within the Yabucoa study area but was excluded from the
ZSF (Puerto Rico Department of Agriculture 1980). It is 8 nmi from alternate
site 1.
3.5 IDENTIFICATION OF ORGANISMS
A taxonomic list of scientific names and common names of species identi-
fied in the Puerto Rico dredged material disposal site areas is presented in
Table 3-5. A similar list for Puerto Rican threatened and endangered species
is presented in Table 3-6.
3-109
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Table 3-5. Taxonomic List of Species Identified in the Study Area of
the Puerto Rico Dredged Material Disposal Sites
Animals
Phylum Coelenterata (Cnidaria)
Class Anthozoa
Subclass Zoantharia
Acropora cervicornis — staghorn coal
Acropora palmata — elkhorn coral
Bartholomea annulata — sea anemone
Montastrea cavernosa — cavernous star coral
Pocillopora sp. — coral
Porites furcata — finger coral
Siderastrea siderea — star coral
Stephanaria sp. — coral
Phylum Rhynchocoela (nemertine worms or ribbon worms)
Unidentified spp.
Phylum Mollusca
Class Gastropoda (snails, conchs, etc.)
Littorina angulifera — periwinkle
Class Pelecypoda (bivalves)
Crassostrea rizophorae — oyster
Nuculana sp. — clara
Vesicomya pilula — clam
Class Cephalopoda
Order Dibranchia
Suborder Octopoda (octopi)
Unidentified spp.
Phylum Annelida (segmented worms)
Class Polychaeta
Euchone sp. — a filter feeding Sabellid tubeworm
Levinsenia uncinata — an herbivorous Paraonid
Melinna sp. — a deposit feeding Ampharetid
Prionospio sp. — a filter/deposit feeding Spionid
Sabellastarte magnifica — a filter feeding Sabellid
tubeworm
Phylum Sipunculida
Golfingia tricocephala — peanut worm
-------
Table 3-5. Taxonomic List of Species Identified in the Study Area of
the Puerto Rico Dredged Material Disposal Sites
(continued)
Animals (continued)
Phylum Arthropoda
Subphylum Mandibulata
Class Crustacea
Subclass Copepoda — copepods
Subclass Malacostraca
Order Decapoda
Aratus pisonii — crab
Callinectes danae — a portunid crab
Gonodactylus oerstedii — mantis shrimp
Macrobrachium carcinus — freshwater prawn
Mithrax sculptus — green crab
Panulirus argus — spiny lobster
Petrolisthes galathinus — an anomuran crab
Stenopus hispidus — shrimp
Phylum Echinodermata
Class Ophiuroidea
Ophiothrix angulata — spiny brittle star
Class Echinoidea
Echinometra lucunter — sea urchin
Class Holothuroidea
Holothuria parvula — sea cucumber
Stichopus badionotus — spotted sea cucumber
Phylum Chordata
Subphylum Urochordata (Tunicata)
Class Ascidia
Ascidia nigra — sea squirt
Subphylum Vertebrata
Class Osteicthyes (bony fish)
Subclass Actinopterygii (ray-finned fish)
Order Beloniformes
Family Hemiramphidae — halfbeaks
Hemiramphus sp. — ballyhoo
Order Beryciformes
Family Holocentridae — squirrelfishes
3-111
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Table 3-5. Taxonomic List of Species Identified in the Study Area of
the Puerto Rico Dredged Material Disposal Sites
(continued)
Animals (continued)
Order Clupeiformes
Family Elopidae — tarpons
Elops saurus — ladyfish
Megalops atlanticus — tarpon
Order Perciformes
Family Balistidae — triggerfishes
Balistes sp. — triggerfish
Family Coryphaenidae — dolphins
Coryphaena equiselis — pompano
Family Gerreidae — mojarras
Gerres cinereus — yellowfin mojarra
Family 1stiophoridae — billfishes
Makaira sp. — marlin
Family Lutjanidae — snappers
Lutjanus sp. — snappers
Family Mugilidae — mullets
Mugil sp. — mullet
Family Mullidae — goatfishes
Family Pomadasyidae — grunts
Haemulon sp. — grunts
Family Scaridae — parrotfishes
Scarus sp. — parrotfish
Sparisoma sp. — parrotfish
Family Scombridae — tunas
Scomber sp. — mackerel
Scomberomorus cavalla — king mackerel
Family Serranidae — sea basses and groupers
Family Sparidae — porgies
Archosargus rhomboidalia — sea bream
Family Sphyraenidae — barracudas
Sphyraena barracuda — great barracuda
Plants
Subdivision Angiospermae (flowering plants)
Class Magnoliopsida
Order Cornales
Family Rhizophoracea (mangroves)
Avicennia tomentosa — black mangrove
Rhizophora mangle — red mangrove
3-112
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Table 3-6. Taxonomic List of Threatened and Endangered Species Identified
in the Study Area of the Puerto Rico Dredged Material Disposal Sites
Animals
Phylum Chordata
Subphylum Vertebrata
Class Reptilia
Order Testudines (Chelonia)
Family Cheloniidae (sea turtles)
Caretta caretta — loggerhead turtle
Chelonia mydas — green turtle
Dermochelys coriacea — leatherback turtle
Eretmochelys imbricata — hawksbill turtle
Lepidochelys sp. — Olive Ridley turtle
Class Aves (birds)
Order Anseriforraes
Family Anatidae
Anas bahamenais — white-cheeked pintail duck
Dendrocygna arborea — West Indian tree duck
Order Pelecaniformes
Family Pelecanidae
Pelecanus occidentalis — brown pelican
Class Mammilia
Order Cetacea
Suborder Mysticeti
Megaptera novaeangliae — humpback whale
Order Sirenia
Trichechus manatus — West Indian manatee
Plants
Pterocarpua officinalis — pterocarp tree
3-113
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4. ENVIRONMENTAL CONSEQUENCES
-------
4. ENVIRONMENTAL CONSEQUENCES
4.0 INTRODUCTION
The following sections of this chapter describe general and site-specific
impacts expected from ocean disposal of dredged material. Section 4.1 dis-
cusses the analytical transport model used to estimate distribution patterns
and concentrations of dumped dredged material. Section 4.2 discusses the
sensitivities of various marine animals to elevated sediment levels. Section
4.3 discusses the lethal and sublethal thresholds for reef-building corals.
Site-specific effects are presented in Sections 4.4 through 4.7. Sections 4.8
through 4.10 discuss the consequences of the proposed site designations for
all harbors.
4.1 METHODS FOR EVALUATING EXPECTED TRANSPORT OF SEDIMENT PLUMES FROM
DISPOSAL SITES
An analytical computer model was developed for this EIS to predict the
transport of dredged materials released at the proposed disposal sites off the
coasts of Puerto Rico. The model calculates the water column concentrations
of solids, based on the specific characteristics of the dredged materials and
the oceanographic characteristics existing at each disposal site. The model
is based on the following parameters:
3
• Volume of disposed dredged material (m )
3
• Density of dredged material (kg/m )
• Water content of dredged material (%)
• Subsurface current speed at disposal site (cm/sec)
• Water density profile
• Dredged material grain size distribution
• Bottom depth profile.
Using these data, the following outputs are generated:
4-1
-------
• Dilution 4 hours after dumping (the suspended sediment dilution
factor)
• Bottom sediment concentration distribution (relating to sedimentation
rate)
• Bottom sediment thickness distribution (relating to burial mound
thickness)
The analytical model is based on the three-phase sediment descent scheme
introduced by Koh and Chang (1973). The phases of descent are:
• Convective descent
• Dynamic collapse
• Passive dispersion
In convective descent, the disposed material sinks rapidly, entraining
ambient water as it sinks. If the mass of dredged material and entrained
water reaches the neutral buoyancy depth (where the density of the diluted
dredged material equals the density of the surrounding water), dynamic col-
lapse begins. In dynamic collapse, the dredged material cloud becomes com-
pressed around the neutral buoyancy depth. After a few minutes of dynamic
collapse, passive dispersion begins. At this point, the dredged material
reacts as individual particles subject to advective, dispersive, and settling
forces until the particles land on the sea floor.
The transport model addresses all three descent phases. Appendix G pro-
vides a detailed discussion of the model's development and application to
determine bottom sediment concentration, thickness distributions and suspended
solids concentration of each plume four hours after dumping.
4.2 SENSITIVITIES OF MARINE ORGANISMS OTHER THAN CORALS TO SUSPENDED
SEDIMENTS ——
Stern and Stickle (1978) reviewed the effects of turbidity and suspended
sediments on aquatic organisms. In these studies, lethal or sub-lethal
effects occurred at concentrations of suspended solids as low as 40 mg/1 for
4-2
-------
the copepod Acartia tonsa and as high as 77,000 mg/1 for the euryhaline shrimp
Palaemon-m^crodactylus (Table 4.2.1).
Among the organisms tested, those with the greatest sensitivity to sus-
pended sediment concentrations included two copepods (which were unable to
feed above thresholds of 40 mg/1 and 250 mg/1), fish eggs (which were delayed
in hatching at 100 mg/1), and bivalve molluscs (which had unusually high rates
of abnormal development at 188 mg/1). Adult benthic crustaceans tested showed
tolerances for much higher concentrations of sediments. Results of 200-hour
LC^q tests for these organisms ranged from 32,000 mg/1 for the Dungeness crab
(Cancer magister) to 7 7,000 mg/1 for the euryhaline shrimp Palaemon macro-
dactylus. A 25-day test with a juvenile Dungeness crab resulted in an
value of 9,000 mg/1, the lowest value for any of the tested benthic crust-
aceans .
Comparison of these sensitivity levels to results of the sediment trans-
port modeling described above indicates that only the most sensitive organisms
tested—the copepods, fish eggs, and perhaps some bivalve eggs—would be
seriously affected by environmental suspended sediment concentrations expected
from open-ocean disposal of dredged materials off Puerto Rico. All effects
observed at relevant concentrations in the laboratory tests were chronic
effects, resulting from an exposure of several hours or days to the test con-
centrations of sediments. Because of the transient nature of suspended sed-
iment plumes in well-flushed, open-ocean waters, neither pelagic (free-
swimming) marine animals such as fish, shrimp, and squid, nor plankton will be
exposed for significant time periods to dredged material disposal plumes.
Principal mechanisms that might result in chronic exposures to turbidity
as a result of disposal at deep, open-ocean sites off Puerto Rico are as
follows:
• Settling and resuspension of materials resulting in elevated turbid-
ities in a layer just above the sea floor,
• Trapping of a portion of the sediment plume in a shallow, poorly-
mixed, or semi-enclosed area where it enters shallow waters near a
coastline, or
4-3
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TABLE 4.2.1. SUMMARY OF THE ADVERSE EFFECTS OF SUSPENDED SEDIMENTS ON MARINE ORGANISMS
Species
Crustacean-Zooplankton
Eurytemora affinis
Copepod
Acartla tonsa
Copepod
Crustacean-Benthic
Anisogamnarus confervicolus
Amphipod
Crangon nigromaculata
Spot tailed sand shrimp
Palaemon macrodactylus
Euryhaline shrimp
Cancer magister
Dungeness crab
Cancer magister (juvenile)
Dungeness crab
Mollusc-Bivalve
Crassostrea virginiea
American oyster
Effect
Result
Fi sh
Perca flaveaceng (eggs)
Yellow perch
Aplodinotua grunniens (eggs)
White perch
Horone chrysops (eggs)
Striped bass
Alosa pseudoharengus (eggs)
Alewife
(b)
Decrease in rate of ingestion 250 mg/1 solids
Decrease in rate of ingestion 40 mg/1 solids^'
200 hour-LC
50
200 hour-LC
50
200 hour-LC
50
200 hour-LC
50
25 day-LC
50
Reduction in number of eggs
developing normally
Delayed hatching
Delayed hatching
Delayed hatching
Delayed hatching
35,000 mg/1 Kaolin(b)
50,000 mg/1 Kaolin(b)
77,000 mg/1 Kaolin^bj
32,000 mg/1 Kaolin(b)
9,000 mg/I Kaolin(a)
188 mg/I silt(b)
100 mg/1 suspended sediment'^'
100 mg/1 suspended sediment^'
100 mg/1 suspended aedinent^b^
100 mg/1 suspended sediment^
Sources:
(a) Peddicord et al. (1978)
(b) Stern and Stickle (1978)
4-4
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• Continuous, intensive disposal operations over a period of several
days or weeks, as might occur from large-scale harbor construction
activities, as opposed to typically short duration maintenance
dredging operations.
4.3 METHODS FOR DETERMINING SENSITIVITY OF CORAL COMMUNITIES TO DREDGED
MATERIAL DISPOSAL
Puerto Rico has well-developed coral reefs along its southern, eastern
and western coastlines. Groupers, snappers, mojarras and many of the other
finfishes caught by the small-scale fisheries depend on coral reef systems for
food and protection. This section describes the types of sub-lethal and
lethal damage to coral reefs that can be caused by turbidity and sedimentation
from dredged material disposal at any location. It explains the methods used
in this EIS to evaluate the potential for coral damage from the use of ocean
Dredged Material Disposal Sites (DMDS's). Later sections of the chapter
evaluate the effects of disposal at the particular interim and alternate sites
considered for each harbor.
4.3.1 Types of Sediment Impact on Reef Communities
Coral reefs grow best in clear, well-flushed waters with low concentra-
tions of suspended sediments and low rates of sedimentation. As turbidity and
sedimentation increase, coral reefs undergo reduction in percent cover, reduc-
tion in species diversity, slowed growth rates, and the elimination of
sediment-intolerant species (Bak 1978; Loy, 1976; Roy and Smith 1971).
There is little quantitative information on the effects of dredging or
dredged material disposal on reef-associated fauna other than corals. The
turbidity effect most frequently reported is the migration of fish from the
affected area (Amesburg 1981; Brock et al. 1966; Galvin 1981). A reduction in
the number of mollusc and echinoderm species has also been reported (Brock et
al. 1966; Galvin 1981). Given the lack of quantitative information, it is
difficult to predict specific effects of disposal on components of the com-
munity other than corals. As noted by Johannes (1978), "So central are corals
to the integrity of the reef community, when they are killed migration or
death of much of the other reef fauna ensues. Therefore the environmental
4-5
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tolerances of the reef community as a whole cannot exceed those of its corals,
and this- f^ct provides us with convenient preliminary criteria for setting up
standards for protecting reef communities from pollution."
The principal mechanisms by which dredged material disposal can damage
reef-building corals are: 1) turbidity; 2) sedimentation; 3) burial; 4) abra-
sion; and 5) toxicity. These mechanisms are discussed in detail in Appendix
E. Three in particular, turbidity, sedimentation and burial, probably present
the greatest threat.
4.3.2 Effects of Turbidity and Impact Threshold Levels
An increase in turbidity decreases the coral growth rates and ultimately
causes mortality by reducing the amount of available light. All reef-building
corals require light because the symbiotic algae contained in their tissues
require light as an energy source for photosynthesis. Coral are dependent on
these algae to produce substances needed in the deposition of the coral's
carbonate skeleton. Continued exposure to high levels of turbidity results in
loss of the algae and eventual death of the coral.
Concentrations of suspended sediment chronically in excess of 10 mg/1
result in significant degradation of coral reefs, with reductions in growth
rates typically occurring at lower concentrations (see Appendix E). Nichols
et al. (1972) reported reefs at St. Croix to be severely stressed by dredging
activities that raised suspended sediment concentration to 10 mg/1 and above.
Reefs of Acropora palmata at St. Thomas were near death in an area where sus-
pended matter concentrations were about 20 mg/1 (Grigg et al. undated, as
reviewed by Rogers 1977). For comparison, ambient concentrations of suspended
sediment in nearshore Caribbean waters are typically below 2 mg/1 with high
winds occasionally raising concentrations to 5 mg/1 (Glynn 1976; Griffin 1974;
1976; Rogers 1977).
4.3.3 Effects of Sedimentation and Impact Threshold Levels
Sedimentation (the relatively gradual settling of sediment particles) can
also result in mortality of corals or sublethal responses such as reduced
4-6
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growth rates. Deposition of sediment on reefs or rocky outcrops can also
inhibit fe-h^-settling of coral larvae, so that new reef areas cannot be
established.
Inhibition of growth for some species has been reported at sedimentation
2
rates of about 1 mg/cm /day (Allen and Dodge 1974). On the other hand Kohle-
mainen (1973) found some species to be unaffected after 9 days exposure to
2
150 mg/cm /day though growth rates were not measured. A review of available
2
literature suggests that two sedimentation rates, 10 and 50 mg/cm /day are
appropriate estimates of thresholds for morbidity and mortality of Puerto
2
Rican corals (Appendix E). At sedimentation rates in excess of 50 mg/cm /day,
only a small fraction of available substrate is typically occupied by living
corals and only the most sediment-tolerant forms are capable of surviving
2
(Randall and Birkaland 1978). Sedimentation rates as low as 10 mg/cm /day kill
or exclude some sediment- intolerant species and produce sublethal responses
in those species that are able to survive. Loya (1976) found that reefs in
2
Puerto Rico exposed to sedimentation at a rate of 15 mg/cm /day were charac-
terized by lower coral species diversity and lower coral coverage of the
2
available substrate than reefs typically exposed to 3 mg/cm /day. Lasker
2
(1980) found that Montastrea cavernosa could remove up to 14 mg/cm /day. M.
Cavernosa was reported to be a comparatively efficient sediment remover, so
that many other species will tolerate significantly less sedimentation.
4.3.4 Effects of Burial
Burial is rapid, essentially instantaneous, smothering beneath a large
amount of sediment, as opposed to the more gradual process of sedimentation.
Most corals can survive burial for only a limited period of time. The dura-
tion of survival depends on the particular species. Porites spp. and
Pocillopora spp. tested by Edmondson (1928) survived burial from 12 hours to
24 hours whereas Stephanaria spp. remained alive after five days. Kolehmainen
(1973) studied the effects of burial on Puerto Rican corals and found that
corals buried for less than 24 hours recovered completely, but tissue disinte-
gration resulted if burial continued more than 30 hours.
4-7
-------
A detailed review of available literature (Appendix E) suggests that
2
burial ben&ath 1.5 ¦ of sediment (approx. 200 mg/cm ) is lethal to many of
the more sensitive species. Independent studies on Puerto Rico corals have
found thi9 depth of burial to cause mortality in Siderastrea siderea
(Kolehmainen 1973) andd Acropora palmata (Rogers 1977). Acropora palmata and
PoriteB furcata, are particularly sensitive corals that are abundant in Puerto
Rican reef communities. Another slightly less sensitive species, Acropora
2
cervicornis, (with a threshold sensitivity of 200 mg/cm per day), is also
common in Puerto Rico.
4.3.5 Conclusion: Coral Sensitivity Thresholds to Sedimentation
Based on the discussions of the preceding section and Appendix E, coral
2 2
sensitivity thresholds considered in this EIS are 10 mg/cm per day (0.1 kg/m
2
per day) of sedimentation for sub-lethal effects, and 50 mg/cm per day (0.5
kg/m per day) for lethal effects. In Sections 4.4, 4.5, 4.6, and 4.7, sedi-
ment dispersal patterns predicted from a transport model are compared to these
threshold levels at each of the alternate sites. The results of those com-
parisons indicate whether the use of particular disposal sites would be
expected to kill corals or to inflict sub-lethal damage by increasing sedimen-
tation rates in areas containing living reefs.
4.4 ENVIRONMENTAL CONSEQUENCES OF DREDGED MATERIAL DISPOSAL FOR ARECIBO
This section summarizes the environmental impacts expected from disposal
at each of the sites considered for Arecibo. A summary of the environmental
characteristics and potential impacts at each site, as they pertain to pro-
tection under the ocean dumping regulations, is presented in Chapter 2 (Table
2-4).
4.4.1 Impacts on Beaches and Shorelines
There will be no measurable increases in sediment concentrations at any
beaches or shorelines because of dredged material disposal at the interim site
or any of the alternate sites. Sedimentation plumes from disposal at any of
the sites would not be expected to reach the waters in the shore zone anywhere
in the Arecibo area (Figure 4-1).
4-8
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I
I
«4°»'
» 4 k|/a la • 140 ¦ by 140 • «re*
* 20 k|/*2 1* • 115 a by 11S m ¦(••
-•00 fc ''
rrrm
»•*
r
-100f,
J,
**"*>•
—r~
*
r
Dooiltloc Concentration*
> * kg/a* to an 100 a by 20b ¦ a
> 20 kt/«2 In a 500 • by U> ¦ ar
Alternate Sin 1
, h
nrm
64 50*
64° 30'
> * kf/¦ la i 600 ¦ by *5 s «r*«
> 20 in a 300 » by 7) • ataa
rmn
I
x
X
n-
FIGURE 4-1.
MAPS OF RECREATIONAL AREAS AND PUBLIC RESOURCES FOR THE INTERIM AND ALTERNATE SITES NEAR ARECIB0
SHOWING SEDIMENT DEPOSITION CONCENTRATION
-------
4.4.2 Impacts on Coral Reefs
There are no major coral reefs in the study area.
4.4.3 Impacts in Preserve or Reserve Areas or Mangrove Nursery Areas
There will be no effects on any natural reserve, Commonwealth forest,
mangrove nursery area or critical wildlife area from disposal at the interim
site or any of the alternate sites. The study area contains the Guajataca
Cliffs critical habitat area, 9-11 mi along the coast to the west of the
harbor, the Carrizales Mangrove Swamp, 4 mi west of the harbor and the
Tiburones Swamp, 1-8 mi to the east. Sediment plumes from disposal at any of
the sites would not be expected to reach the water in or immediately adjacent
to any of these areas (Figure 4-1).
4.4.4 Effects on Threatened and Endangered Species
Disposal at any of the sites considered would not affect sea turtle habi-
tats. It is not known to what extent marine turtles feed in the mangrove
areas near Arecibo, or nest on its beaches. However, all potential disposal
sites are well offshore from any possible sea turtle feeding or breeding habi-
tats, and the minimal ocean transport predicted by the model for this area
would not be sufficient to carry released materials at significant concentra-
tions into the nearshore waters (Figure 4-1).
For the same reason, there will be no effect on brown pelicans from dis-
posal at any of the sites. Breeding areas and principal feeding areas for
pelicans are close to shore and released materials would not be transported
into those waters in appreciable quantities. Because there would be no signi-
ficant horizontal transport of the sediment mass before it reaches the sea
floor at any of the potential Arecibo sites, it is unlikely that pelicans
would fly over and feed from waters containing suspended sediments in the
short time period before the disposed materials reached the sea floor.
4-10
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4.4.5 Shipping Lanes
There are no designated shipping lanes in the harbor. No significant
impact to shipping is expected from the disposal of dredged material at any of
the sites.
4.4.6 Mineral Resources
No effects are expected on any mineral resources from disposal at the
interim site or any of the alternate sites. No such features have been iden-
tified in the Arecibo ZSF. There are known deposits of magnetite sands south
of the ZSF and it is possible that these deposits may extend into the southern
part of the ZSF near the interim site. However, sediment plumes from disposal
at any of the sites would not be expected to reach the deposits.
4.5 ENVIRONMENTAL CONSEQUENCES OF DREDGED MATERIAL DISPOSAL FOR MAYAGUEZ
This section summarizes the environmental impacts expected from disposal
at each of the sites considered for Mayaguez. A summary of the environmental
characteristics and potential impacts at each site, as they pertain to pro-
tection under the ocean dumping regulations, is presented in Chapter 2, (Table
2-5).
4.5.1 Impacts on Beaches and Shorelines
There will be no measurable increases in sediment concentrations at any
beaches or shorelines because of dredged material disposal at the interim or
alternate sites. Sedimentation plumes from disposal at any of the sites would
not be expected to reach the waters of the shoreline anywhere in this area
(Figure 4-2).
4.5.2 Impacts on Coral Reefs
There should be no adverse effects on corala from the disposal of dredged
materials at any of the alternate sites. Use of the interim site, however, is
likely to result in deposition of sediments at levels harmful to corals in the
reef areas just south of the Site (Figure 4-3). Use of any of the alternate
sites is expected to result in sediment plumes that disperse and then settle
4-11
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tlGURE
4-2. SEDIMENT DEPOSITION RELATIVE TO ARECIBO LIVING RESOURCES
-------
67°30" 67°20' 67°10' 6?°30' 67°iO' 67°i0'
67°20' 67®10' "'JO* 67°W' *7°10'
FIGURE 4-3. MAPS OF RECREATIONAL AREAS AND PUBLIC RESOURCES FOR THE INTERIM AND
ALTERNATE SITES NEAR MAYAGUEZ SHOWING SEDIMENT DEPOSITION CONCENTRATION
4-13
-------
out before reaching any of the area's reefs. Use of the interim site, how-
ever, will not typically result in dispersion of the dredged materials in an
extended plume. This is because the bottom at this site is sufficiently
shallow that the mass of released materials will land on the sea floor before
reaching the state of dynamic collapse and dissipation. Consequently, sedi-
ment deposition concentrations at or near much of the Site will be very high,
well above the value of 2 kg/m2 found to cause mortality in sedimentsensitive
corals such as Porites furcata and several of the Acropora species, all of
which are quite common in this region. Concentrations lethal to these corals
could be reached at the principal deposition area as a result of release of
one typical barge load of dredged material. Continuous use of the site over a
period of several days would result in sediment accumulation to levels that
would be lethal to even more resistant coral species.
Figure 4-4 incates that the location of the sediment mound predicted from
this model is actually between a half and one nmi away from the nearest
charted coral reef area. However, uncertainties about current speed, direc-
tion, and point of release (e.g. release may not begin in the center of the
Site as was assumed in the model), means that the actual mound location could
be displaced by at least one nmi from the predicted location. Thus, it is
possible, and in fact likely over a period of years involving numerous
disposal operations, that navigational and current conditions would combine to
create unacceptably high levels of sediment deposition on the reefs adjacent
to the interim site.
Disposal at any of the alternate sites would not create high levels of
sediment deposition in any coral area. This is because the sea floor at these
sites is deeper than the level at which the inital mass of released sediments
will reach its depth of neutral density and begin the process of horizontal
mixing in a dispersion plume. Plumes from disposal at each of the alternate
sites will dissipate to levels approximately equal to minimum average near-
shore sedimentation rates in Puerto Rico (0.05 kg/m ) before reaching any
known coral reefs.
4-14
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J
'///¦
Xaportaat Coaaarclal
» laportant Sport
Flatting Araaa
,* - Coral laala/lot torn
Araaa
Sad taant D«po»11Ion Concantratlona
> 4 kg/a* in a 97 a radlut of ale* ctntar
> 20 kg/a* In an 83 ¦ radlu* of alta cantar
Nautical Nllaa
nrrm
67 20'
—r—
9
r
100 fa*
¦MtlMl KtlM
rrrm
* Concentrations ahewn la kg/a'
1«°
X
6? 20'
—1~
100 fB'
NmcImI Nilw
HHi)
17°30'
47*10'
~
NMlttl DUN
(TTTTT1 ' Cl
ii®
•7*20'
FIGURE 4-4. SEDIMENT DEPOSITION RELATIVE TO MAYAGUEZ LIVING RESOURCES
4-15
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4.5.3 Impacts in Preserve or Reserve Areas or Mangrove Nursery Areas
There will be no effects on any natural reserve, Commonwealth forest,
mangrove nursery area, or critical wildlife area from disposal at the interim
site or any of the alternate sites. The only such features within the study
area are the Joyuda Lagoon mangrove reserve, 5 mi along the coast to the
harbor, the Guanajibo River mangrove area, 3 mi to the south, and the Anasco
River mangrove area, 5 mi to the north of the harbor. Sediment plumes from
disposal at any of the sites would not be expected to reach the water in or
immediately adjacent to any of these features (Figure 4-3).
4.5.4 Effects on Threatened and Endangered Species
Disposal at any of the sites would not affect sea turtle habitats.
Marine turtles are reported to nest in the Cabo Rojo region, south of the
Joyuda Lagoon. All potential disposal sites are at least 7 nmi away from this
area, and ocean transport, as predicted by the model, is not sufficient to
carry released materials to this area (Figure 4-3).
For the same reason, there will be no effect on the brown pelican from
disposal at any of the sites. Pelicans are primarily a nearshore species and
would thus only rarely, if ever, fly over and feed from waters in the dredged
material plumes<
4.5.5 Shipping Lanes
There are no designated shipping lanes in the harbor. No significant
impact on shipping is expected from the disposal of dredged material at any of
the sites.
4.5.6 Mineral Resources
There will be no effects on any mineral resources from disposal at the
interim or alternate sites. A large quartz sand deposit is located about 1/2
nmi west of Alternate Site 2 and extends seaward (Cox and Briggs 1973).
Sediment plumes from disposal at site 2 could reach these quartz sand
deposits, but the area likely to be affected is small compared to the total
size of the resource.
4-16
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4.6 ENVIRONMENTAL CONSEQUENCES OF DREDGED MATERIAL DISPOSAL FOR PONCE
This Section summarizes the environmental impacts expected from disposal
at each of the sites considered for Ponce. A summary of the environmental
characteristics and potential impacts at each site, as they pertain to protec-
tion under the ocean dumping regulations, is presented in Chapter 2 (Table
2-7).
4.6.1 Impacts on Beaches and Shorelines
Several beaches and stretches of shoreline would be affected by the sedi-
ment plumes created by disposal under typical oceanographic conditions at
Ponce (Figure 4-5). There are several beach areas west of Ponce Harbor that
could be affected. The closest of these is beyond Punta Cucharas, approxi-
mately 4 nmi from the interim site. Other beaches are located to the west,
one off Punta Verraco and two others along the coastline of the Guanica
Commonwealth Forest, which is designated as a reserve area by the Forestry
Service of the Puerto Rico Department of Natural Resources. Disposal at the
interim site or Alternate Sites Nos. 2 or 3 would result in concentrations in
2
these areas exceeding the threshold sedimentation value of 0.01 kg/m that is
expected to cause unacceptable effects, on nearshore water quality under the
second general criterion of the ODR. Use of either of these disposal sites
for a typical disposal operation would be expected to cause a detectable
increase in ambient sedimentation levels in nearshore waters. Disposal at
Alternate Site No. 1 (the proposed site) is not expected to cause adverse
impacts to beaches and shorelines.
4.6.2 Impacts on Coral Reefs
There should be no adverse effects on corals from the disposal of dredged
materials at any of the evaluated sites. The only large coral reefs are out-
2
side the area of influence of the 0.1 kg/m sediment deposition plume. Al-
though reefs to the northwest may be exposed to lower levels of sedimentation
(Figure 4.6), no adverse effects on corals there are expected.
4-17
-------
FIGURE 4-5. MAPS OF RECREATIONAL AREAS AND PUBLIC RFSOURCES FOR THE INTERIM AND ALTERNATE SITES NEAR PONCE
SHOWING SEDIMENT DEPOSITION
-------
¦p-
I
17°
I
T.
*~*50'
I
T
i (k«n la k|/>
'///* laftrtut CMMveial
ri«kl«| *tiM
- tspartaat Sfort
ri*kt*| Araaa
#•, # - Coral tMf(/Uttra
nrm
klttriiet Sit* 2
b I } i i i
u"
*
T
Alternate Site 1
¦Mtlttl HILm
mrn
tlt*rn(tc Sit* 3
¦Htlai MILm
4 I 1 1 i 1
FIGURE 4-6. SEDIMENT DEPOSITION RELATIVE TO PONCE LIVING RESOURCES
-------
4.6.3 Impacts in Preserve or Reserve Areas, or Mangrove Nursery Areas
There yij.1 be no effects on any natural reserve, Commonwealth forest,
mangrove nursery area or critical wildlife area from disposal at the interim
or alternate sites. Such features within the Ponce study area include the
Guanica Commonwealth Forest and adjacent critical habitat area, 7-12 mi along
the coast to the west of the harbor, the Guayanilla Bay mangroves, 6-7
miles west of the harbor, Cabullan mangroves, 3 miles to the east, Punta
Petrona mangroves and Aguirre Commonwealth Forest, 12 miles to the east. Also
in the study area is the Caja de Muertos Island Reserve, 5 nmi east of alter-
nate site 3, which includes the Berberia Key, 3 nmi to the northeast. It is
possible that disposal at the interim site under certain typical oceanographic
conditions would produce a plume of sediment at above ambient levels that
would be transported into the nearshore waters of the coastal Guanica Common-
wealth Forest and its protected adjacent lands. However, sedimentation levels
in that preserve's coastal waters would not be expected to exceed the minimum
2 ....
0.5 kg/m threshold expected to damage sensitive marine organisms (Figure
4-5).
4.6.4 Effects on Threatened and Endangered Species
Disposal at any of the sites under consideration would not affect sea
turtle habitats. Sea turtles are reported to nest on Caja de Muertos Island.
All disposal sites are to the west of the island, so that the westward flowing
currents typical in the area will tansport dredged materials away from the
island. For the same reasons, there will be no effect on the brown pelican
from disposal at any of the sites. Pelican habitats are close to shore and
released materials will not be transported there in any appreciable
quant it ies .
4.6.5 Shipping Lanes
There are no designated shipping lanes in the harbor. No significant
impact to shipping is expected from disposal of dredged material at any of the
sites.
4-20
-------
4.6.6 Mineral Resources
There .will be no effects on any mineral resources from disposal at the
interim or alternative sites. No mineral resources have been identified in or
near the ZSF.
4.7 ENVIRONMENTAL CONSEQUENCES OF DREDGED MATERIAL DISPOSAL FOR YABUCOA
This section summarizes the environmental impacts expected from disposal
at each of the sites considered for Yabucoa. A summary of the environmental
characteristics and potential impacts at each site, as they pertain to pro-
tection under the ocean dumping regulations, is presented in Chapter 2 (Table
2-9).
4.7.1 Impacts on Beaches and Shorelines
Several beaches and stretches of shoreline would be reached by the sedi-
ment plumes created by disposal under typical oceanographic conditions at
Yabucoa (Figure 4-7). There are several beach areas southwest of Yabucoa
Harbor that could be affected. The closest of these is Playa Maunabo, approx-
imately 10 nmi from the interim site. Another is located to the southwest off
Cabo Mala Pascua. Disposal at Alternate Site 1 would result in concentrations
2
at this site that could exceed the threshold sedimentation value of 0.01 kg/m
that is expected to cause unacceptable effects on nearshore water quality.
Use of this disposal site for a typical disposal operation would under some
typical oceanographic conditions be expected to cause a detectable increase in
sedimentation levels in nearshore waters. Disposal at the interim site and
Alternate Sites 2 and 3 would not result in concentrations that exceed the
threshold sedimentation value and is therefore not expected to cause any unac-
ceptable effects on nearshore water quality.
4.7.2 Impacts on Coral Reefs
Modeling indicates that there would not be adverse effects on corals from
the disposal of dredged materials at Alternate Sites 2 or 3. The principal
2
coral reefs in the area are not within the area of influence of the 0.1 kg/m
sediment deposition plume, although reefs to the southwest may be exposed to
4-21
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eMCMtntlMi tkai .MB k|/a
wlthla tl to mf ik« «lu.
A I J i 4 }
FIGURE 4-7.
U*lM' »5*»' « «•' Woo' »!•»•
MAPS OF RECREATIONAL AREAS AND PUBLIC RESOURCES FOR THE INTERIM AND ALTERNATE SITES NEAR YABUCOA
SHOWING SEDIMENT DEPOSITION
-------
2
lower levels of sedimentation not expected to harm corals (0.05 kg/m ) (Figure
4.8). No adverse effects on coral are expected below sedimentation concentra-
2
tions of 0'. 1 kg/m . However, serious adverse coral impacts may occur from
continued use of the interim site. Live corals inhabiting the shallow north-
western portion of the site were identified by acoustic identification of hard
bottom areas, together with inadvertant collection of portions of live reef
corals during bottom sampling on the 1984 survey cruise. In addition to the
probability that materials released in the site will be deposited on corals
inhabiting the site itself, there is also a high probability that severe storm
conditions at some future time would cause resuspension and transport of
materials away from the original deposition mound and into the shallow areas
inhabitied by corals. Modeling of storm resuspension is described in Appendix
H.
Because disposal at alternate site 1 would also be expected to result in
transport into nearshore waters, it is possible that use of that site would
also result in sediment deposition on corals present in shelf areas.
4.7.3 Impacts in Preserve or Reserve Areas, or Mangrove Nursery Areas
There will be no effects on any natural reserve, Commonwealth forest,
mangrove nursery area or critical wildlife area from disposal at the interim
or Alternate Sites. The Ceiba Commonwealth Forest, 10-12 mi along the coast
to the north of the harbor, the Humacao Mangrove Swamp, 7 mi to the northeast,
and the Vieques Critical Wildlife- Area on the westernmost end of Vieques
Island, 5 nmi northeast of Alternate Site 3, are located within the study
area, but sediment plumes from disposal at any of the sites would not be
expected to reach the water in or immediately adjacent to any of these fea-
tures (Figure 4-7).
4.7.4 Effects on Threatened and Endangered Species
There is no site under consideration where disposal would affect sea
turtle habitats. Rare marine turtles are reported to nest on Vieques Island
13 to 14 nmi east of Yabucoa. All study sites are well offshore of this area,
and ocean transport is not sufficient to convey released material at concen-
4-23
-------
FIGURE 4-8. SEDIMENT DEPOSITION RELATIVE TO YABUCOA LIVING RESOURCES
-------
trations of concern to the critical area (Figure 4-7). For the same reason,
there will be no effect on the brown pelican from disposal at any of the
sites. Breeding and feeding areas for pelicans occur much closer to shore
than the sites considered.
4.7.5 Shipping Lanes
There are no designated shipping lanes in the harbor. No significant
adverse impact will result from the disposal of dredged material at any of the
proposed sites.
4.7.6 Mineral Resources
There will be no effects on any mineral resources from disposal at the
interim or alternate sites. No mineral resources have been identified within
the ZSF. A major quartz sand source is located about 5 nmi to the north of
the ZSF, beyond the island of Vieques (Grove and Trumball 1978). Sediment
plumes from disposal at any of the sites would not be expected to reach this
deposit.
4.8 IRREVERSIBLE AND IRRETRIEVABLE COMMITMENT OF RESOURCES FOR ALL HARBORS
Use of the proposed sites will require expenditure of funds to pay costs
of transporting dredged materials to the site, which will include costs of
fuel, an irretrievable resourcce. Disposal of dredged materials at the sites
will not result in irretrieval cqmmitment of other resources. There will be
changes in the benthic marine ecosystem where dredged materials are deposited,
but these are not expected to have irreversible effects on any marine
resources.
4.9 STEPS TO MINIMIZE ADVERSE EFFECTS TO THE ENVIRONMENT FOR ALL HARBORS
Principal potential environmental effects of dredged material disposal at
the four proposed DMDSs are as follows:
• Reduction of localized water quality during short initial mining
period.
4-25
-------
• Burial of benthic invertebrates in localized sediment deposition
areas. (This is most likely at Arecibo, and less likely in other areas
due.to dispersion of released materials over deep water).
The effects of dumping will be mitigated as long as the barge is in
motion during the disposal operation, to increase dispersion of released
sediments.
4.10 RELATIONSHIP BETWEEN SHORT-TERM USE OF THE ENVIRONMENTAL AND ENHANCEMENT
OF LONG-TERM USE OF THE ENVIRONMENT FOR ALL HARBORS
The designation and use of the proposed Arecibo, Mayaguez, Ponce and
Yabucoa disposal sites will result in short-term changes in benthic ecosystems
where sediments are deposited. Short-term and long-term enhancement of human
uses of the environment in these regions will result because the availability
of sites for dredged material disposal will allow for maintenance dredging of
harbors required to support regional commerce and industries. Ocean disposal
provides an alternative to environmentally less desirable land-disposal
options for each harbor.
4-26
-------
S. CONTRIBUTORS TO THE EXS
-------
5.0 CONTRIBUTORS TO THE EIS
This EIS was prepared with the assistance of the technical and scientific
staff of the Environmental Toxicology and Ecological Assessment Division and
the Water Programs Division of JRB Associates (JRB), McLean, Virginia and JRB
offices in Seattle, Washington and La Jolla, California. Applied Sciences
Associates (ASA) provided a resuspension model for the project. This section
summarizes the backgrounds and qualifications of the primary contributors to
the EIS and indicates the sections to which they contributed.
The EIS was prepared under the direction of Mr. Robert Hargrove of the
Environmental Impacts Branch of the Environmental Protection Agency,
Region II. Mr. Hargrove served as the Government's Work Assignment Manager.
Ms. Linda Comerci of the Region II Water Permits and Compliance Branch
assisted Mr. Hargrove in reviewing the preliminary draft.
Paul Campanella, Ph.D.
Dr. Campanella was the JRB Project Manager for the EIS. He has a Ph.D.
in Ecology/Resource Management from Syracuse University. Dr. Campanella is
the JRB Environmental Toxicology and Ecological Assessment Division manager.
F. Kim Devonald, Ph.D.
Dr. Devonald was the Work Assignment Manager and Technical Coordinator
for the EIS. She has a Ph.D. in Oceanography from the Scripps Institution of
Oceanography. As Work Assignment Manager and Technical Coordinator, Dr.
Devonald has managed the technical staff in the organization and writing of
the EIS.
The technical contributors to individual sections of the EIS are
identified in Table 5-1.
5-1
-------
TABLE 5-1. CONTRIBUTORS TO THE ENVIRONMENTAL IMPACT STATEMENT
RESPONSIBLE
PERSON
CHAPTER
APPENDIX
1
2
3
4
B
C
D
E
F
G
H
MANAGEMENT STAFF
Paul Campanella
Ph.D. Ecology/
Resource Management
X
X
X
X
X
X
X
X
Kim Devonald
Ph.D. Oceanography
X
X
X
X
X
X
X
X
X
X
TECHNICAL STAFF
Vivien Bacaner
M.S. Environmental
Science
X
X
X
X
Terry Grist
B.A. Geography/
Human Ecology
X
X
X
X
Constance Spooner
B.S. Agronomy/
Soil Science
X
X
X
X
X
Andrew Stoddard
Ph.D. Environmental
Engineering
X
X
X
X
Cindy Van Duyne
B.A. Biology/
Environmental
Studies
X
X
Richard Wagner
M.S. Environmental
Engineering
X
X
X
-------
TABLE 5-1. CONTRIBUTORS TO THE ENVIRONMENTAL IMPACT STATEMENT (Continued)
RESPONSIBLE
PERSON
CHAPTER
APPENDIX
1
2
3
4
B
C
D
E
F
G
H
Jeff Weiler
M.S. Resource
Economics/
Environmental Mgmt.
X
X
X
X
Roger Wells
M.S. Ocean
Engineering
X
X
Don Weston
Ph.D. Marine Science
X
X
X
Janet Zuckerman
MPH Water Quality/
Environmental and
Industrial Health
X
X
X
X
ASA (Applied Science
Associates)
Malcolm Spaulding
Ph.D. Ocean
Engineering
X
5-3
-------
GLOSSARY, LIST OF ABBREVIATIONS, AND UNIT CONVERSION TABLE
-------
6.1 GLOSSARY
ABUNDANCE - Relative number of individuals of a species inhabiting an area.
AMBIENT - The existing conditions of an environment.
AMPHIPODS - An order of crustaceans; the two marine groups of amphipods,
hyperiideans and gammarideans, inhabit open ocean waters or are bottom
dwellers.
ASSEMBLAGES - A group of organisms sharing a common habitat.
BATHYMETRY - The bottom topography (distribution of bottom depths) of an
aquatic region.
BASELINE CONDITIONS - The physical, chemical and biological conditions exist-
ing in an environment prior to an activity that might change the condi-
tions of that environment.
BENTHIC - Pertaining to the bottom in an aquatic system, including soft-bottom
and hard-bottom conditions; [organisms]: living in or on the sea floor
or in or on the soft or hard bottom of a fresh or brackish water
environment.
BENTHOS (BENTHIC ORGANISMS) - Marine animals or plants living on or in bottom
sediments.
BIOASSAY - Exposure of a test organism to a sample to determine the lethal
concentration of a pollutant to the organism.
BIOGEOGRAPHIC - Geographic distribution of animal and plant life.
BIOMASS - The mass of living matter, including stored food, present in any
given volume of habitat.
BIOTA - The animal and plant life living within a given area.
BLOOM - High concentration of aquatic plants that results from rapid repro-
duction due to an increase of nutrients.
CALCAREOUS OOZE - A fine-grained pelagic deposit containing more than 30
percent calcium carbonate.
CIRCULATION PATTERN - The general geometric configuration of oceanic currents.
CLAMSHELL DREDGE - A crane-operated device used for dredging in confined
areas. The device consists of two shell-like halves that are lowered in
an open position and then mechanically closed to contain and remove
dredged material.
CLAY - Sediment with particle diameters less than 1/256 mm.
6-1
-------
CONTINENTAL MARGIN - Zone separating continental land masses from the deep sea
floor.
CONTINENTAL SHELF - The zone bordering a continent extending from the line of
permanent immersion to the depth (usually about 180 m) where there is a
rather steep descent toward the great depths.
CONTINENTAL SLOPE - The slope from the outer edge of a continental shelf to
the deep sea floor.
CRUSTACEANS - Animals with jointed appendages and a segmented external
skeleton. The group is primarily aquatic. It includes crabs, shrimps,
lobsters, mysids, amphipods, and microscopic benthic and planktonic
forms.
CURRENT METER - A device used to measure the speed and direction of flowing
water.
CURRENT SHEAR - The measur| of^the spatial rate of change of current velocity
with units of cm-sec m
DEMERSAL - Living in the water near the bottom, and typically finding food on
the bottom.
DIATOMS - Free-floating algae with siliceous external skeletons.
DILUTION - A reduction in concentration.
DISPERSION - The dissemination of discharged material over large areas by
turbulence and currents.
DISSOLVED OXYGEN - Amount of oxygen dissolved in a unit volume of water.
DIVERSITY - A measure of the variety of species in a community.
DOMINANCE - Control by a species or group of species of the energy flow and
environment within a community.
DREDGING - Removal of sediment from the floor of a body of water in order to
maintain an adequate clearance for shipping.
DRY WEIGHT - The weight of remaining biomass after the water has been removed
from a sample.
ECHINODERMS - Principally benthic marine animals having calcareous plates with
projecting spines forming a rigid or articulated skeleton or plates and
spines embedded in the skin. These organisms have a radially symmetri-
cal, usually five-rayedi body and include the sea starfish, sea urchins,
crinoids, and sea-cucumbers.
ECONOMIC RESOURCE ZOljlE - The ocean zone within 200 nautical miles from shore
in which the adjacent coastal state possesses exclusive rights to the
living and non-living ocean resources.
6-2
-------
ECOSYSTEM - An ecological community together with its physical environment,
considered as a unit, each influencing the properties of the other and
both necessary for the maintenance of life.
EDDY - A current of water moving contrary to the direction of the main cur-
rent; typically a circular motion.
EPIPELAGIC - Ocean zone ranging from the surface to a depth of 200 meters.
F0RAMIN1FERA - Single-celled, planktonic protozoans possessing shells, usually
of calcium carbonate.
GASTROPODS - Molluscs with a distinct head, generally with eyes, tentacles, a
broad, flat foot, and a spiral shell.
HOPPER DREDGE - A self-propelled hydraulic dredge that utilizes a trailing
dredge head. Dredged material is deposited in a storage area — "hopper"
— and later dumped or pumped onto a disposal site.
HYDRAULIC FILL - The deposition at a disposal site of dredged slurry by means
of centrifugal pumping action.
ICHTHYOPLANKTON - Fish eggs and weakly motile fish larvae.
INDICATOR SPECIES - A species of organism characteristic of a certain water
mass.
IN SITU - In the natural or original position.
ISLAND MASS EFFECT - A phenomenon in which the abundance or biomass of
organisms in the immediate vicinity of an island is markedly higher than
the surrounding oceanic area.
ISOPODS - The second largest order of crustaceans. These flattened bottom-
dwelling arthropods are generally scavengers.
LC^q - A bioassay or toxicity measure to determine the concentration of pollu-
tant that causes 50 percent mortality in the population of test organisms
during a unit time ("lethal concentration for 50 percent").
MACROZOOPLANKTON - Planktonic organisms with lengths between 200 and 2000
raicra, composed mainly of copepods, chaetognaths, and larval forms.
MER0PLANKT0N - Organisms that spend only a portion of their life cycle as
plankton; usually composed of floating developmental stages (i.e., eggs
and larvae) of the benthos and nekton organisms. Also known as temporary
plankton.
MICRO-NUTRIENT - Substance that an organism must obtain from its environment
to maintain health, though necessary only in minute amounts.
6-3
-------
MICRO-ORGANISMS - Microscopic organisms, including bacteria, protozoans,
yeast, viruses, and algae.
MIXED LAYER - The upper layer of the ocean that is well mixed by wind and wave
activity. Within this layer temperature, salinity, and nutreint concen-
tration values are essentially homogeneous with depth.
NERITIC - Relating to the waters over the continental shelf.
NMI - Nautical mile; the length of one minute of longitude at the equator.
One nmi is equal to 1.151 statute miles.
ORTHO-PHOSPHATE - One of the salts of orthophosphoric acid; one of the compo-
nents in seawater that is of fundamental importance to the growth of
marine phytoplankton.
OXIDATION - The process in which a substance gives up oxygen, removes hydrogen
from another substance, or attracts negative electrons.
PARTICULATE CARBON - Finely divided solid particles of carbon suspended in the
water column.
PELAGIC - Free-swimming: living in water and having sufficient strength of
movement that the major force of movements is due to own actions rather
than to passive transport along with water currents.
PHYTOPLANKTON - Minute passively floating plant life of a body of water; the
base of the food chain in the sea.
PLANKTON - Aquatic animals and plants, usually small and often microscopic in
size, that drift passively with ambient water movements; the plants
(phytoplankton) are unicellular algae, the animals (zooplankton) include
protozoans (unicellular) and a wide variety of tiny multicellular
animals. Multicellular zooplankton are mostly crustaceans, but also
include the larvae of benethic animals, small specialized worms, and
gelatinous animals related to sea squid or jellyfish.
POLYCHAETE WORMS - Segmented worms (of the phylum Annelida), forming a major
group that is primarily aquatic. Among the most diverse and abundant
groups of non-microscopic benthic animals.
PRIMARY PRODUCTION - The amount of organic matter synthesized by organisms
from inorganic substances in a given time in a given volume of water, or
in a given amount of space in a terrestrial system.
PTEROPODA - The sea butterflies, an order of pelagic gastropod molluscs in
which the foot is modified into a pair of large fins and the shell, when
present, is thin and glasslike.
PYCNOCLINE - The depth at which the density of seawater changes maximally.
REACTIVITY - The tendency of a substance to combine with another substance.
6-4
-------
RECRUITMENT - Addition to a population by reproduction of new individuals or
species.
SAND - Sediment with particle diameters ranging from 1/16 to 2 mm.
SEA STATE - Numerical or written description of ocean surface roughness: the
average height of the highest one-third of the waves observed in a wave
train.
SECCHI DISC - A device used to measure the clarity of seawater.
SHOAL - A shallow area within a harbor, river, etc. Shoaling is the result of
deposition of sediment by prevailing currents.
SILT - Sediment with particle diameters ranging from 1/256 to 1/16 mm.
SLURRY - The mixture of sediment and water that is collected by dredging
activities.
TEMPORAL DISTRIBUTION - The geographical range of an organism over time.
TERRIGENOUS - Relating to sediment derived directly from the erosion of rocks
on the earth's surface.
THERMOCLINE - The region of the water column where temperature changes most
rapidly with depth.
TROPHIC LEVELS - Any of the feeding levels through which the passage of energy
of an ecosystem proceeds. Typical marine trophic levels include: phyto-
plankton, zooplankton, fish.
TURBIDITY - The degree of decreased optical clarity of water (due to
suspended or dissolved materials).
UPWELLING - The rising of water toward the surface from subsurface layers of a
body of water. Upwelling is most prominent where persistent wind blows
parallel to a coastline so that the resultant wind current sets away from
the coast. The upwelled water, besides being cooler, is rich in
nutrients, and regions of upwelling are generally also areas of rich
fisheries.
VERTICAL DISTRIBUTION - The frequency of occurrence over an area in the
vertical plane.
WET WEIGHT - The weight of a sample of organisms before interstitial water is
removed.
ZOOPLANKTON - The passively floating or weakly swimming animals of an aquatic
ecosystem.
6-5
-------
6.2 LIST OF ABBREVIATIONS AND ACRONYMS
AS: -Alternate Site
CEC: Cation Exchange Capacity
COE: U.S. Army Corps of Engineers
CODREMAR: Corporation for the Development of Lacustrine, Estuarine, and
Marine Resources (Puerto Rico)
cm: centimeter
cm/sec: centimeters per second
DM: Dredged Material
DMDS: Dredged Material Disposal Site
EIS: Environmental Impact Statement
EPA: Environmental Protection Agency
IS: Interim Site
kg: kilogram
km: kilometers
km^: square kilometer
1: liters
LC50: lethal concentration for 502 of individuals
LPC: limiting permissable concentration
m: meters
3
m : cubic meters
MEC: maximum environmental concentration
mg: milligrams
mg/1: milligrams/liter
mi: miles
ml: milliliters
mm: millimeter
MPRSA: Marine Protection, Research and Sanctuaries Act
6-6
-------
6.2 LIST OF ABBREVIATIONS AND AUKUMIMS
(continued)
NEPA: National Environmental Policy Act
nmi: nautical miles
NWF: National Wildlife Federation
NOAA: National Oceanographic and Atmospheric Administration
ODR: Ocean Dumping Regulations
o/oo: parts per thousand
%: percent
PRDPW: Puerto Rico Department of Public Works
PRNC: Puerto Rico Nuclear Center
USGS: United States Geological Survey
ZSF: Zone of Siting Feasibility
ug-at: microgram-atoms
6-7
-------
6.3 UNIT CONVERSION TABLE
To Convert
To
Muliply By
Length:
inches
cent imeters
yards
meters
miles
kilometers
miles
nautical miles
nautical miles
kilometers
Area:
square inches
square centimeters
square yards
square inches
acres
hectares
Weight:
ounces
grams
pounds
kilograms
tons
metric ("long") tons
Velocity:
miles per hour
knots
knots
centimeters per second
Depth:
centimeters 2.54
inches 0.39
meters 0.90
yards l.ll
kilometers 1.61
miles 0.62
nautical miles 0.87
miles 1.15
kilometers 1.85
nautical miles 0.54
square centimeters 6.49
square inches 1.54
square meters 0.8
square yards 1.25
hectares 0.40
acres 2.47
grams 28.0
ounces 0.04
kilograms 0.45
pounds 2.22
metric ("long") tons 0.9
tons 1.11
knots 0.87
miles per hour 1.15
centimeters per second 51.0
knots 0.02
fathoms
meters
fathoms
feet
fathoms
meters
6
0.55
1.83
Volume:
cubic yards
cubic meters
cubic meters
cubic yards
0.76
1.32
-------
7. references
-------
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