United States Region 4 EPA 904/6-84 121
( Environmental Protection 345 Courtland Street, NE June 1984
Agency Atlanta. GA 30365
&EPA Supplement To Final Draft
Environmental Impact
Statement
Final Designation
Georgetown Ocean Dredged
Material Disposal Site
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DRAFT SUPPLEMENT TO FINAL
ENVIRONMENTAL IMPACT STATEMENT
IMI
FINAL DESIGNATION GEORGETOWN OCEAN DREDGED MATERIAL DISPOSAL SITE
/ Prepared by
U.S. Environmental Protection Agency
Region IV
Atlanta, Georgia 30365
Cooperating Agency
U.S. Army Corps of Engineers
Charleston District
APPROVED BY:
rles R. Jeter """" I
'gional Administrator
Date
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TABLE OF CONTENTS
SUMMARY
I PURPOSE OF AND NEED FOR ACTION
II ALTERNATIVES (Including the proposed action)
Mid-shelf or Shelf Break Region
Nearshore Sites in Same General Area as Existing ODMDS
EPA Does Not Designate An ODMDS for Georgetown
Corps Seeks Designation
No Dredging
Upland Disposal
Disposal in "Waters of the U.S."
Ill AFFECTED ENVIRONMENT
Mid-shelf and Shelf Break Areas
Nearshore Environment
Existing ODMDS and "Control" Site
Graphic and Tabular Summaries of Selected
Physical, Hydrographic, Chemical, Sedimentological,
and Biological Information on the South Atlantic
Bight and the Nearshore Waters and Existing ODMDS
in Particular
IV ENVIRONMENTAL CONSEQUENCES AND MINIMIZATION OF
ADVERSE IMPACTS
The Existing ODMDS
The Nearshore Area, Other Than the ODMDS and "Control" Site
Mid-shelf and Shelf Break Regions
Upland Disposal Sites and "Waters of the U.S."
V. PREPARERS AND REVIEWERS OF THE EIS
APPENDIX A
Graphic and Tabular Summaries of Beam Trawl Data
From the Existing ODMDS, "Control Site, and "Down
Current" Sites, Collected by the South Carolina
Wildlife and Marine Resources Department During
The Winter and Summer of 1983
APPENDIX B
Graphic and Tabular Summaries of Benthic Grab Data
From the Existing ODMDS, "Control" Site, and "Down
Current" Sites, Collected by the South Carolina
Wildlife and Marine Resources Department During the
Winter and Summer of 1983
APPENDIX C
Draft Ocean Dredged Material Disposal Site Designation
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SUMMARY
This supplement to the Final EIS for Savannah, Ga.,
Charleston, S.C., and Wilmington, N.C. Ocean Dredged Ma-
terial Disposal Site Designation (ODMDS) considers permanent
designation of a similar site for the Georgetown Harbor area,
which lies within the South Atlantic Bight region described
in the Final EIS.
The Port of Georgetown, although considerably smaller
than Charleston in terms of shipping commerce, contributes to
the overall economy of the State. For over 30 years, the
Charleston District, Corps of Engineers, has dredged material
from the Georgetown Harbor entrance channel and deposited the
material on nearby, predominantly sandy substrate. The
impacts of harbor maintenance were discussed in the Corps'
March 1976 Final EIS for Georgetown Harbor. Since 1977 the
currently used Georgetown ODMDS has been designated by
EPA as an interim site, pending study and final designation
in accordance with the Marine Protection, Research, and
Sanctuaries Act of 1972 (MPRSA). In October 1983, EPA filed
a Final EIS for the permanent designation of Savannah, Ga.,
Charleston, S.C., and Wilmington, N.C., ODMDS's. Originally,
as recorded in the 9 December 1980 Federal Register (Vol. 45,
No. 238), the Georgetown ODMDS was to have been part of this
multiple-site designation, and the studies that supported the
designation EIS covered, both geographically and topically,
the portion of the South Atlantic Bight in which the Georgetown
ODMDS is located.
The maps, descriptions, and explanations that appear in the
Final EIS for Savannah, Charleston, and Wilmington ODMDS's
and the site-specific evaluation of the Georgetown ODMDS
(summarized in Chapter 3) show that the rationale used to
reject mi'd-shelf and shelf break alternative sites for
Savannah, Charleston and Wilmington also apply to Georgetown.
Upland disposal of material is not feasible because of the
excessive pumping costs and because all of the land near the
entrance channel is part of the Thomas Yawkey Foundation or
the Belle W. Baruch Foundation holdings which are managed for
wildlife preservation, and research.
The designation of a nearshore Georgetown ODMDS other than
the existing site is possible but was rejected because of the
following reasons:
(1) Previous use of the existing ocean site has failed
to cause any problems such as mounding, significant alteration
of substrate or benthic communities or water quality degradation,
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(2) Arbitrary selection of another nearby site might
result in unforseen problems not encountered at the existing
site.
(3) There are no plans in the forseeable future to
ocean dump materials different than those now being deposited
in the Georgetown ODMDS.
(4) Permanent designation of the interim site based on
current and planned uses would in no manner imply that all
material dredged in the future could be dumped at this
location. A separate analysis of each type of dredged
material, the quantity proposed for disposal, and the
compatibility of the material with the ODMDS would be required.
If a newly proposed material does not satisfy the criteria
established pursuant to Section 102(a) of the MPRSA, it can
not be dumped at the designated site.
(5) The interim (existing) site is relatively close to the
entrance channel. Relocation of the site even three of four
miles away would greatly increase hauling and operating costs.
The affected environment of the nearshore waters around
Winyah Bay includes the existing ODMDS and the shallow (less
than 20m) area seaward to the mid-shelf region, 10 nautical
miles from shore. Nearshore waters are greatly influenced by
the large discharges through Winyah Bay, salt marshes, and
the North Santee River; by strong tidal action, which alters
longshore currents; and by seasonal weather patterns.
Sediments in and around the existing ODMDS are medium to
coarse sands with little «1%) silt and clay. No hard bottom
areas have been found in or near the existing ODMDS; however,
the nearshore of South Carolina is typically variable and
hardbottom sites may exist elsewhere. Several commercially
important finfish and shellfish species migrate through
nearshore areas to adjacent coastal areas. Two endangered
marine species, the short-nosed sturgeon and the loggerhead
turtle are known to be present along this section of the coast
at certain times of the year. Suspension feeders dominate
the benthic infauna. Pelecypods, polychaetes, amphipods, and
bryozoans are the most numerous; polychaetes are the most
diverse taxonomic group.
Short summaries of the mid-shelf, shelf break, inland
waters, and uplands that were briefly considered as alternatives
appear in Chapters II and III. Because these sites were rejected
early for economic and environmental reasons, the summaries
are not repeated here.
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Consequences of the proposed action (designation of the
existing ODMDS) are limited mainly to smothering of aquatic
organisms by burial and temporary increases in turbidity.
Detailed examination of the ODMDS after repeated use shows
no significant adverse long-term effects due to mounding or
changes in water quality, substrate type, or benthic communities
Hauling dredged material to mid-shelf, shelf break,
inshore waters ("of the U.S.") or upland sites would increase
costs by about ?157,000 per mile (round trip). Environmental
impacts of ocean dumping at mid-shelf and shelf break areas
could be greater than at the existing ODMDS because the
substrate, water quality, and benthic organisms at the off-
shore sites would be different and less compatible with heavy
suspended sediment loads. The impacts of disposal in Winyah
Bay, nearby wetlands, or uplands now managed for wildlife
preservation and research are not acceptable.
Dumping material at nearshore sites, even a few miles
away from the entrance channel, would greatly increase costs.
For much of the nearshore area, environmental consequences
would probably be similar to those at the existing ODMDS, but
they would be greater at certain landward locations and could
be greater at some less well studied sites.
EPA knows of no controversies or outstanding issues with
this proposal. There is no reason to incur the additional
costs of hauling dredged material to more distant sites where
the environmental impacts may be greater or are less well
understood. If, at some later date, materials not suitable
for disposal at the existing ODMDS are proposed for dumping,
disposal of this material may be denied, the ODMDS may be
moved, or a new ODMDS may be designated.
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I. Purpose and Need
This document presents the environmental evaluation of
alternatives for permanent designation of an ocean dredged
material disposal site for Georgetown, South Carolina. The
Marine Protection, Research and Sanctuaries Act (MPRSA)
authorizes EPA to designate a permanent disposal site when a
need has been established and an environmentally suitable site
is available. Section 102(a) of this act requires EPA to
establish criteria for the ocean dump sites and for material
which can be disposed at these sites. These criteria are
presented in EPA's Final 1977 Ocean Dumping Regulations (40
CFR, Part 227, Subpart C).
Pages 1-5 through 1-19 of the Final EIS for Savannah,
Charleston, and Wilmington ODMDS designations contain a
thorough discussion of the Marine Protection, Research, and
Sanctuaries Act, a history of the Act's implementation,
including regulations, establishment of dumping and designation
criteria, and international considerations. That discussion
is incorporated by reference rather than repeated here.
On the average, over 500,000 tons of commerce are shipped in
deep draft vessels through the Georgetown Harbor entrance
channel each year. The Port of Georgetown is essential to
the continued operation of the biggest industries in the
Georgetown area, Georgetown Steel and International Paper
Companies. Other items, such as hardwood lumber, are shipped
through the port and contribute to the economy of the larger
S.C.- N.C. region. The significance of the port to the local
economy was detailed in a March 1979 "Georgetown Navigation
Project Study," prepared by Enviroplan, Inc., for the South
Carolina State Ports Authority. The per capita income for
Georgetown County is among the lowest and the unemployment
rate is the highest in South Carolina, a state that routinely
ranks near the lowest and near the median, respectively, in
the country for these two statistics.
The Georgetown Harbor entrance channel is maintained at 27
feet, a depth that limits navigation to relatively small
ocean-going vessels. In order to maintain the benefits
attributed to navigation, dredging in the entrance channel is
necessary, on the average, once per year, and an average of
450,000 cubic yards is removed during each dredging effort.
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II. Alternatives (including the proposed Action)
The proposed action is the designation of the existing ocean
dredged material disposal site (ODMDS) for Georgetown Harbor.
This rectangular shaped site covers approximately one square
mile and lies three miles off the entrance to Winyah Bay on
the south side of the channel, in 20 - 36 feet of water
(MLW). In order to understand the significance of the proposed
action and the range of alternatives to this action, one must
be aware that the Marine Protection, Research, and Sanctuaries
Act (MPRSA) requires two separate procedures to be followed
before material can be dumped at an ocean site. The first is
a designation of the site to be used, based upon its
environmental suitability as a dump site. The suitability is
determined by application of criteria developed pursuant to
Section 102(a) of the Act. The designation may include
restrictions as to the time and type of material to be dumped,
if necessary to protect critical areas. The second procedure
following the site designation is the process described in
Section 103(b) of MPRSA which is an evaluation of a proposed
harbor dredging project. Assessments are then made of the
particular types and quantities of materials to be dumped,
the compatibility of the materials with the substrate and
biota at the ocean disposal site, and the impacts of the
proposed disposal on "human health, welfare, or amenities, or
the marine environment, ecological systems, or economic
potentialities." The site designation proposed in this
Supplement will in no manner p\ermit the disposal of any and
all materials at the site without the second assessment procedure,
Alternatives to the proposed action are:
\r
(1) Designation of an ODMDS considerably farther from
shore (mid-shelf or shelf break region) than the existing site.
(2) Designation of another ODMDS in the same general
area as the existing ODMDS.
(3) Not designating any ODMDS for Georgetown. Options
then available to the Corps of Engineers and any other
potential ODMDS user would be:
(a) Dispose of materials at an upland site.
(b) Dispose of materials in "waters of the U.S."
(regulated by Section 404 of the Clean Water Act).
(c) Stop dredging (no disposal site required).
(d) An agency or individual proposing ocean disposal
might, itself, seek designation of an ODMDS, rather than use
an ODMDS recommended by EPA. In this case, the range of
ocean dump sites would be the same as that available to EPA,
and this option is not further discussed here.
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Designation of an ODMDS in the Mid-shelf or Shelf-break Region
Mid-shelf and shelf-break alternatives were considered in
pages 2-11 through 2-33 of the Final EIS for Savannah,
Charleston, and Wilmington ODMDS designation, which has been
incorporated into this Supplement by reference. In the Final
EIS, the mid-shelf and shelf-break regions were broadly
characterized, and the Georgetown offshore area lies within
the portion of the South Atlantic Bight (SAB) so characterized.
With the exception of a few parargraphs dealing specifically
with Charleston, Savannah, or Wilmington, the broad descriptions
apply equally well to Georgetown. Figures 4,5,9-11, and 17-
19 in Chapter 3 of this Supplement are reproduced from the
Final EIS.
The Final EIS described the mid-shelf and shelf break regions
as follows:
"The mid-shelf extends from approximately 10 to 50
nautical miles from shore. In general, bottom depths
on the shelf increase gradually from 20 to 60 m, with
an average slope of 36 cm/km. The shelf-break occurs
at depths of 50 to 70 m, from approximately 50 to 70
nautical miles from shore."
"Physical and biological characteristics of the mid-
shelf region of the SAB are influenced by seasonal
oceanographic and climatic patterns, and episodic Gulf
Stream intrusions. The mid-shelf is covered with medium-
grained sands with scattered low to moderate relief,
hard-bottom terrain. Rocky reefs support diverse and
productive invertebrate assemblages, and demersal and
pelagic finfish species. Consequently, reefs are
important to commercial and recreational fisheries.
Primary productivity in mid-shelf waters is limited by
nutrient inputs from Gulf stream intrusions and upwelling.
Soft-bottom, benthic communities have high biomass
relative to nearshore areas, especially in areas
contiguous with reefs;11
"The physical and chemical characteristics (seawater
temperatures, salinities, nutrients, and trace metal
concentrations) of the Shelf break region of the SAB
are strongly influenced7 by the Gulf Stream. Extensive
but discontinuous Lithothaminon and Black Rock Reefs
occur at depths of 100 to 200m, and are productive
areas for invertebate and demersal finfish species
(Pequegnat, 1978). Sandy-mud bottom regions are
characterized by depauperate, but heterogenous infaunal
assemblages."
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A mid-shelf and shelf break site alternative to the nearshore
proposed ODMDS were not specifically investigated. However,
sites in these offshore zones would be expected to be quite
similar to those considered in the Final EIS for Savannah,
Charleston and Wilmington. Available environmental data lead
to the findings in the Final EIS which support the rejection
of mid-shelf and shelf break ODMDS1s in the South Atlantic
Bight (SAB) and show that the rationale presented in the
Final EIS for their rejection is applicable to Georgetown
without change:
"No dumping has occurred previously in either region
(mid-shelf or shelf break) of the SAB.
Baseline studies would be needed to provide data on
water quality, ecology, and the presence or absence
of sensitive, natural, or cultural resources.
The additional costs of transporting materials further
would be significant.
Dredged sediments are not physically similar to either
mid-shelf or shelf break sediments, thus the probability
of altering sediment texture and adversely affecting
benthic organisms is higher.
Monitoring and surveillance would be more difficult due
to the greater depths and distances from shore.
The probability of inadvertent dumping of dredged materials
on sensitive hard-bottom areas during rough weather is
higher."
Designation of Another ODMDS in the Same General Area as the
Existing ODMDS
The nearshore environment in the South Atlantic Bight is
shallow (less than 20m) and strongly influenced by coastal
processes: "runoff from rivers and salt marshes, longshore
sediment transport, winter storm effects, and anthropogenic
inputs" (Final EIS). In the vicinity of the Georgetown ODMDs,
tidal currents strongly affect nearshore current direction
and velocity, and wave action extends throughout the water
column to the bottom. The Final EIS generally characterized
the nearshore bottom sediments as "fine to very fine-grained
sands with some river-derived silts." In the Georgetown
ODMDS and in the "control" site on the northern side of the
entrance channel (Figure 1), the bottom sediments, possibly
winnowed by wave and current activities, are moderately to
poorly sorted clean coarse sand. Sediments "down current"
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(to the southwest) are finer, but the differences are not
statistically significant. To the north of Winyah Bay and in
other scattered locations, even finer-grained sands mixed
with silt are encountered.
As part of a study* under contract to the Charleston District,
Corps of Engineers, the South Carolina Wildlife and Marine
Resources obtained information on the nearshore coast of
Georgetown. Figures 2, 3, 6-8, 12-14 in Chapter III and figures
in Appendices A and B to this Supplement are reproduced from
this SCVvMRD report, also incorporated into the Supplement by
reference. .
Because of the large freshwater discharge through Winyah Bay
and strong tidal action, water quality is highly variable but
within the ranges normally encountered along the South Carolina
coast (SCWMRD Georgetown ODMDS report). Figure 16 of this
Supplement shows a massive turbidity plume caused by this
discharge engulfing the existing ODMDS. Some water quality
parameters have been graphically summarized in the next
chapter.
The Final EIS described the nearhsore biological communities
of the SAB as "characterized by benthic infaunal assemblages
with low abundances and high diversity, productive penaeid
shrimp and anadromous fish species, and hard-bottom assem-
blages." The SCWMRD site-specific study of the Georgetown
ODMDS and surrounding area documented the "large seasonal and
spatial variability in species composition and abundance,
which is typical for nearshore environments throughout the
South Atlantic Bight". However, the SCWMRD study differed
from the Final EIS in reporting greater number of species and
a dominance by suspension feeders rather than by small-bodied
deposit feeders. Shrimp and sturgeon are two of the many
commercially and ecologically significant nektonic species in
the nearshore area which must be considered in the selection
of an ODMDS and, more importantly, in the determination of
the types and quantities of material to be dumped at the site.
Although a nearshore ODMDS, other than the existing site, was
an alternative that received considerable attention during
the field studies and evaluations that were conducted prior to
the preparation of the draft EIS supplement, it has since
been eliminated from serious consideration.
* "Benthic and Sedimentological Studies of the Georgetown
Ocean Dredged Material Disposal Site," January, 1984. South
Carolina Wildlife and Marine Resources Department. Robert
Van Dolah et.al. authors.
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Downgrading of this alternative was due mainly to findings of
Charleston District surveys and the SCWMRD study of the
existing ODMDS, which showed that 30 years deposition of
entrance channel materials have not caused significant long-
term changes such as mounding, degradation of water quality,
or significant alteration of substrate or benthic communities.
Based on these findings, there is no reason to relocate the
ODMDS to a nearby area where there is no history of previous
use, and there are several reasons why such a move might
result in adverse impacts:
-Relocation of the ODMDS considerably closer to shore
might adversely affect loggerhead turtle nesting,
shellfishing areas, or other landward resources.
-A detailed study of an area to the north of the en-
trance channel (originally chosen for a "control"
site; see Figure 2) showed differences in sediments
between the "control" and the existing site, but the
differences were not significant.
-A survey of existing data shows that although the
Georgetown nearshore area is fairly typical of the
South Carolina coast, there exists some variability
within the area. Less well studied sites might not be
as suitable as the existing site.
-The Landsat photograph (Figure 16) and field data show
that an area around the entrance channel receives
large amounts of freshwater runoff heavily laden with
suspended sediments. Dumping-of dredged material out-
side this plume area might result in greater impacts
to water quality and marine fauna, since sites outside
the plume are not directly and frequently subjected to
influxes of these sediment-laden waters.
-Movement of the ODMDS away from the entrance channel
would increase costs by about $0.35/c.y. per mile
(about $157,500 for a typical contract). The biggest
increase would be in operating costs (equipment,
salaries, per diem, etc.) due to the non-productive
time when the hopper dredge is hauling material rather
than dredging.
No changes in current disposal practices are anticipated for
Georgetown Harbor. If significantly different materials are
proposed for ocean dumping, this alternative can be reconsidered
in the required Section 103 evaluation. At present, there is
no reason to incur the added costs or to take a chance that
unforseen adverse impacts might occur at sites which have not
received dredged material in the past and have not been
studied in as much detail as the existing ODMDS and the
"control site".
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The approximate quantities of material dredged from Georgetown
Harbor Entrance Channel over the last ten years are as follows:
Date Gross Cubic Yards
1973 (Sept) 255,000
1974 (Sept) 389,000
1975 441,000
1976 (Jun-Aug) 476,000
1977 (Dec) 200,000
1978 NONE
1979 (Jan-Feb) 170,000
1980 (Jan-Apr) 546,000
1981 NONE
1982 (Jul-Aug) 538,000
1983 NONE
1984 (May) 425,000
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Do Not Designate Any ODMDS for Georgetown
If EPA failed to designate an ODMDS for Georgetown, the Corps
of Engineers probably would seek permanent designation of the
existing ODMDS. The proposed action and the alternatives
would not be substantially different than the EPA action;
however, failure by EPA at this stage to designate an ODMDS
as originally proposed would greatly extend the process, and
would probably result in the entrance channel not being
maintained at authorized project depth until the designation
process is complete.
A permanent halt to dredging in the entrance channel would
result in permanent loss of the navigation benefits attributable
to the project. Since the Georgetown Harbor project has been
authorized by Congress and continues to be vital to the local
economy, a halt to dredging is not a practical option.
Disposal of entrance channel materials on upland sites is
also not practical. Hauling and/or pumping costs, together
with mobilization costs, would be prohibitive. The nearest
upland sites are part of the Thomas Yawkey Foundation or the
Belle W. Baruch holdings. Since these lands are generally
managed for preservation, wildlife and research, disposal of
sandy material and salt water on these lands would be
incompatible with most of the present land uses. Disposal
upland is not being permanently set aside in favor of ocean
disposal. Each applicant for an ocean disposal permit must
fully evaluate the availability and environmental impact of
feasible upland sites. For the Georgetown area, there are
designated upland sites which are reserved for poor quality
dredged spoil from inner harbor areas.
Disposal of dredged materials into "waters of the United
States," including Winyah Bay and nearby streams and wetlands,
is generally prohibited when there are reasonable alternatives.
Wetlands and open waters regulated under Section 404 .of the
Clean Water Act are protected because of their roles as
spawning, breeding, and nursery areas for many marine and
estuarine species; their tunction in maintaining water quality;
the habitat provided to wildlife; recreation and other uses.
In the case of Georgetown Harbor, ocean disposal at the
existing ODMDS is a proven and superior alternative to disposal
in estuarine or wetland areas. Further, the cost of hauling
and/or pumping the dredged material to landward waters would
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be much greater than hauling it the short distance to the
existing site.
III. AFFECTED ENVIRONMENT
The affected environment of the South Atlantic Bight was
described in Chapter 3 of the Final EIS and is incorporated
into this Supplement by reference. Chapter II of the SCVvMRD
report on the Georgetown ODMDS reviewed existing information
on the South Carolina coastal environment and the Georgetown
area in particular. Chapter IV of that same report provided
detailed evaluations of the bottom sediments, hydrography,
and benthic communities in the existing ODMDS, in a similarly
sized site to the north of the entrance channel ("control"
site), and in three stations to the southwest of the existing
ODMDS. These chapters are also incorporated into the Supplement
by reference, with the notation that the recommendations and
suggestions at the end of Chapter IV are those of the SCWMRD
and are not necessarily those of the Corps of Engineers or EPA.
Mid-Shelf and Shelf Break Areas
A brief verbal summary of the mid-shelf and shelf break areas
appears in Chapter II , of this Supplement. Graphic
summaries of selected environmental data appear in Figures 4,
5, 9-11, and 20-22 which follow. For further information,
the reader is directed to the two documents referenced above.
Rather than paraphrase the large amount of data in these two
reports, they have been made readily available.
Nearshore Environment
A brief verbal summary of the nearshore ocean area appears in
the preceeding chapter of this Supplement. The figures ana
tables that follow summarize further some of the environmental
data collected or reviewed in the Final EIS and the SCWMRD
study. Sources for the figures and tables and additional
information on nearshore waters can be found in these two
documents. when any differences appear between the broad
descriptions of the Final EIS and the site-specific information
in the SCVvMRD study, the latter should be considered more
precise. (E.g., the SCWMRD study reported a larger mean,
grain sediment size, a higher number of benthic faunal species,
and a predominance of suspension feeders over small-bodied
filter feeders.)
Of the commercially important fisheries, the SCWMRD report
emphasized the Atlantic sturgeon (Acipenser oxyrhynchus) and
shrimp because of their proximity to the ODMDS during certain
times of the year. The shortnose sturgeon (Acipenser
brevirostrum) and loggerhead turtle were mentioned as endangered
species sometimes in the vicinity of the ODMDS.
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The Existing ODMDS and "Control" Site
Prior to the SCVvMRD study of the Georgetown ODMDS, it was
thought that if significant changes to the bottom substrate
and benthic community had taken place as a result of 30 years'
ocean disposal, the effects would be most easily detected at
the ODMDS and "downcurrent" (based upon the generally southerly
direction of nearshore currents) stations. Analysis of SCVvMRD
study data indicated that there were no significant long-term
changes in the benthos due to dumping and that the differences
observed between the existing ODMDS and "control" site were
probably due to substrate differences not related to dumping.
The use of the site to the north of the channel as a "control"
site was, therefore, greatly diminished, but the detailed
data permits an accurate evaluation of this site as an
alternate nearshore ODMDS. The following is from the SCWMRD
report.
"Standard hydrographic factors, which included temperature,
salinity, dissolved oxygen, and turbidity were within
the limits normally encountered along the South Carolina
coast. Some seasonal and spatial differences were
discerned for each factor. High runoff via Winyah Bay
resulted in reduced salinities and increased turbidities
at some sites. Moderately high turbidities in summer
may have been the result of frequent shrimp trawling in
the area. Currents in the DMDS appear to be largely
tidal, although some evidence of a southerly nearshore
current was noted. Trace contaminants in water samples
were within or below ranges noted in other areas of the
South Atlantic Bight. Many trace metals were below
detection limits, as were PCBs and all pesticides
tested."
"Sediment analyses indicated that bottom sediments at
most of the sampling sites consisted of medium to coarse
sands with very little «1%) silt and clay. Stations
to the south of the DMDS had consistently finer-grained
sediments than those in the DMDS and control areas, but
no statistically significant differences were noted
among sites. Sediments were low in trace metal and
organic contaminant concentrations. Comparisons with
other studies indicated that sediments in and near the
Georgetown DMDS cannot be considered polluted. No hard
bottom areas were found in the entire study area."
"Benthic epifauna and fishes captured in beam trawl
collections were typical of those from sand bottom
habitat of South Carolina coastal waters. Community
structure was influenced by season, and the number of
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species was significantly higher in summer. Species
assemblages were noticeably different in winter than
in summer, with several species occurring during only
one season. Although the total number of species was
lowest in the disposal area, comparison of species
composition among the sites indicated that lower diver-
sity resulted from fewer sessile species, mainly bryo-
zoans and cnidarians. This suggests that less substrate
was available for colonization by sessile organisms in
portions of the disposal area, although, lesser amounts
of hard substrate (i.e., wood, shell) in the DMDS were
probably not related to past disposal activities.
Tissue analysis of whelks (Busycon carica) collected in
and near the DMDS did not reveal any high concentrations
of contaminants."
"The infauna collected in grab samples at the 13 off-
shore stations were numerically dominated by pelecypods,
polychaetes, amphipods and bryozoans. Polychaetes were
the most diverse taxon. Of the 357 species collected,
many were limited in abundance of frequency of occur-
rence. The dominant species, however were generally
ubiquitous throughout the study area and exhibited
considerable temporal and spatial variation. No signi-
ficant differences could be attributed to past disposal
activities with respect to species composition or faunal
density among the control, disposal and "down current"
sites. Unlike the deposit-feeding communities previously
described for the SCW-DMDS, the Georgetown DMDS and
vicinity were characterized by a seasonally variable,
diverse community of suspension-feeding organisms.
Numerical classificatin of the data illustrated some
differences in similarity between stations in the
control site versus those in the disposal and "down
current" areas, particularly during winter. These
difference probably were not related to previous disposal
practices. Rather, they were most likely due to natural
variability in sediment composition. Cluster analysis
also indicated that most of the abundant and frequently
occurring species were widely distributed throughout
the study area."
-------
•Ol
»07 «IO
CONTROL SITE(CS)
( «02 »05 •OB «l| «l'4
I »03 »06 909 »I2 •H5
JETTY
WIN YAH BAY ENTRANCE
*07
. DISPOSAL SITE (OS)
' «O2 «OB •OS •!) «f
I »03 «0e »09
• 03 «OI
DOWN CURKENT SITES (DC)
• 02
Oiitanca
I Km
Figure 2 Map showing location of the 15 possible sampling locations
In the control and DMDS sites, as well as the location of
"down current" and channel sampling locations.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
-17-
Figure 3 Three-dimensional plot of bottom survey data collected in the
Georgetown DMDS by the U.S. Army Corps of Engineers, April 1983.
Rectangular boundaries represent the DMDS boundaries and dots
represent the stations sampled during winter and summer in the
present study. The vertical scale is greatly exaggerated relative
to the horizontal scale.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
-18-
• NEAKSHORE
• MID-SHELF
A SHELF BREAK
WILMINGTON
QEORGETOVV
SAVANNAH
81'
80*
78*W
33'
32'
31'N
Figure U Nearshore, Mid-Shelf, and Shelf-Break Alternative Areas
Source: Final EIS on Savannah, Charleston, and Wilmington ODMDS designation
-------
-19-
— 34'
COASTAL CURRENTS
^ MAICH
SEPTEMBER
WILMINGTON
GULF STREAM
APFIOXIMATE AXIS OF
MAXIMUM SPEED
— 31'N
Figure 5 Surface Currents Over the South Atlantic Bight Shelf
Source: BLM, 1978
Source: Final EIS on Savannah, Charleston, and Wilmington ODMDS designation
-------
"BLACK
RIVER
HTDROCSAPHIC STDBY AUAS
ma 4,6,7,8,9.13
I* "1 Off«bor«
L_±l 1.2,3.5,8,10.11^
S^ *
12,14
SDRTACSCT11CDLATI ON»
1974
V>-4.%+4
\ — • • r -r T, -r -r -r T» TTT-TTTTT
r ^^ 4* + + + 4* +, + + 4" 41* 4'^4> + + 4> + H
* * * + +• 4- +V+ •*• * *\t- 4" 4- 4- * 4- 4- f
**4-4-4-4>4''> 4-Jt * + 4. 4- + 4. 4. 4.* +
£\4.^4-^4-^4-^1. 4- 4- «4.*-X4.'*'4.+'*S|^*4.'l'4.'f4.'l'4.'1'
1T + + + + + +.4-+-4' 4-*+ 4-*4."f4- 4-*4.*4.'t'4.'1'
'4"4-4-4.^4>4-4'4'4'4'4"4-4'4'4'4.4.4»
»• 4- *• 4- -AMH 4- 4- 4>_4- 4-4-4-4-4-4-4-4-4-4.
+ 4> i*. 4> ~«W 4- 4> + + + + + + 4> + + 4>4>4
, 4- 4- 4J 4- 4*^- T».4> 4.4.4-4.,4.4-4.4.4.4.» 4.
' * 4. 4- It- 4- T.* +>*4.4.4.|. + 4.4.4.4.4.4.
* + 4l 4- •*••+>*« * *^* 4.4-I4-4.4.4.4-4.4.4.
, 4.4.4-U.4-4-4-V4. *Kt 4- k-^f 4- 4- 4- 4- 4- 4-
* * 4l 4- 4- 4- 4- », 4- 4- ^—f'< 4> 4- + 4- 4- 4- 4.
J 4.4-+*4'4.4-4'-»4.4-4-l*.4.4.4>-(-4-4.4-4
**4T****4-\*4-A4.4>4.4>4-4-4.4-
t-»4.4-4-4'4.4'4-»4- +ft- 4- + *4-4-4-4-4
4-4»4- + 4-4>4.4.4-«»4-j4.4.4.4.4.4.4. 4-
>-*4-4-4.4-4>4-4.4-*J- 4>lb- 4- 4> 4- 4- 4- 4- 4-
4>4>4-4-4'4>*4'4' +• 4- •r4-4-4-4-^4>4-4>
H* + + * + + + + 4--S4. 4-V 4> 4- + 4- 4- 4-
4-4.4- + 4-4-4-4. + 4-4J + 4>^4> 4> 4> 4> 4> 4- 4.
»'4' + *'4'4'4'4'4' + 4.»4-4.4>4.4.4.4.4.4
h-»4-* + 4>4'4.4-4.4'4-».
. * + 4> 4> 4> 4> +• 4>| I I 1
/+* + + 4-4-4>* _ 4- 4-
t4. + 4.4> + + 4-4'
\4-4.4.4-4-4-4.4-
J + 4>4>4' + 4' + 4>
i.4-4>4-4> + 4>4-4- \ - \ 4.4.4.
*t.*4.* + * + * + * + .* \ SOUTH N. • 4- 4- 4|
4.4-4.4.4-4-4- V CA«OUMA . / ^
Arrows are approximations
and do not represent current^
•elocities or specific data
loints.
4- + 4- 4- 4- 4> 4.
/4-4. + 4>4.4-4-4-4.
4'4'4'4'4'4'4-4-
4-4- + 4>4'4>4'4'4'
4-4. + + + 4-4.4-
4> 4- 4- 4- 4- 4-
^4- 4> 4. 4> 4- 4- 4
+ 4- 4> 4- 4- 4>
H 4- 4- 4- 4- 4 4- 4|Q ».
/4»4-4-4.4-4-4-4- M
4.4-4-4-4-4-4-4- 4-Ji
Hounoat Mita*
Figxore 6 Location of hydrographic study areas and surface circulation
patterns: ^-Bureau of Land Management (BLM), 1981; 2Mathews and
Pashuk, 1977; %tethevs and Pashuk, 1982; *Allen, et al., 1982;
SChurgin and Halminski. 1974; 6Hinde, ec al., 1981; 7Johnson,
1970; 8Jones, Edmunds and Assoc., 1979a, 1979b, 1979c; ^Mathews
et al., 1981; 10Minerals Management Service (MMS), 1982;
^Science Applications Inc. (SAI), 1981a, 1981b; 12SAJ, 1983a,
1983b; IJShealy, 1974; 14south Carolina Wildlife and Marine
Resources Dept., 1979.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-20-
-------
DOWN CURRENT SITES
Current velocity
(knoti) 0
Depth
— Surface
- — Bottom
Tidal Phot*
I Flood
S Slacktlhr
Figure 7 Current velocities and directions for the 13 stations
sampled during the winter in and near the Georgetown
Harbor DUDS.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
IN3
I—>
I
-------
SUMMER
WINY AH BAY ENTRANCE
Dltlanca
I K«
Current velocilw
(knots) 0 1
I\/S ££JUROL SITES
i* t~ T^ i
'______vt--j
DISPOSAL.
i«s ^.-^ \
„
5 •(
DOWN CURRENT SITES
Deptf
— Surface
- Bottom
Tidal Phase
- Flood
S Slack* I hr
Figure 8 Current velocities and directions for the 13 stations sampled
during the summer in and near the Georgetown Ilarhor DMDS.
ro
r\>
i
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
-23-
FEBRUARY
MAY
AUGUST
NOVEMBER
Figure 9 Frequency of Waves Greater Than 12 ft (3.6m)
in Height in the South Atlantic Bight
Source: BLM, 1978
Source: Final EIS on Savannah, Charleston, and Wilmington ODMDS designation
-------
-24-
WILMINCTON
CHARLESTON
SAVANNAHS
• • "•*
ZONED SEDIMENT LITHOFACIES
MEDIUM TO COARSE TERRIGENOUS
SANO AND GRAVEL
FINE TERRIGENOUS SANO
COARSE CALCAREOUS
SANO AND GRAVEL
FINE CALCAREOUS SANO
j FINE CAMONATE SAND
MUD
— 30*N
rrw
Figure 10 Areal Distribution of Sediment Lithofacies;
Cape Remain to Cape Canaveral
Source; Pilkey et al., 1979
Source: Final EIS on Savannah, Charleston, and Wilmington ODMDS designation
-------
-25-
GRAIN SIZE DISTRIBUTION
COAISC SANO (OJ to 1 Jt mm)
MEDIUM SANO (&2S to 0-S mm)
FINE SANO (0.12 to 0^3 mm)
— 30-N
Figure 11 Areal Distribution of Mean Grain Size;
Cape Ronain to Cape Canaveral
Source: Pilkey et al., 1979
Source: Final EIS on Savannah, Charleston, and Wilmington ODMDS designation
-------
-26-
Figure 12 Area! distribution of mean grain size: t>ilkey et al., 1979;
2MMS, 1982.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
-27-
CH01X?
MEAN GRAIN SEDIMENT SIZE
JETTY
CH02
kfljrtL~siTj~_~_
jtmr
WINY AH BAY ENTRANCE
V^C.-r-n^Sv^1
1 • • ; %t$rt**S.9S<7t°• »^/
•„*:% •/;\riJ
Co*r«« S«nd<0.0-1.0+)
Medium 3*nd( 1.0-2.0*)
V«ry Fin* Sand
(3.0-4.0*)
Coirs* Sllt(4.0-5.0*)
Figure 13 Distribution of mean grain size of sediments collected
from the Georgetown DIIDS and vicinity.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
-28-
25%,
75%
Clayey Sand
CH02*
50%
.25%
12 Remaining
25%
50%
75%
Figure 14 Shepard's classification of sediment types at stations in
the Georgetown DMDS and vicinity.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
-29-
% CALCIUM CASBONATE
jrrnr
JETTY
WINYAH BAY- ENTRANCE
Figure 15 Distribution of percent calcium carbonate content of
sediments collected from the Georgetown DMDS and vicinity,
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
-30-
Figure 16 Landsat photograph of Winyah Bay and nearshore coastal waters. Note
the large plume of turbid water which encompasses the DMDS area.
Lighter area at bottom of photograph is reflection of the sun.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
Table 1 Oceanographic parameters of water collected from the 7 winter and 9 summer stations sampled
in and near the Georgetown Harbor HMDS.
WINTER
S II M M E R
Station
DSOJ
nsi3
CS02
OS 17
DC01
r<:o2
I1C03
Station
Depth Depth
8.0 Surface
Middle
Bottom
11.0 Surface
Middle
Bottom
9.5 Surface
Middle
Bottom
11.0 Surface
Middle
Bottom
8.73 Surface
Middle
Bottom
8.25 Surface
Middle
Bottom
6.5 Surface
Middle
Bottom
Temp.
(C)
8.
8.
8.
8.
8.
8.
9.
8.
8.
8.
9.
8.
9.
9.
9.
9.
9.
9.
8.
8.
8.
7
7
8
5
6
7
2
9
9
9
0
9
4
4
3
0
0
0
5
7
9
Salinity
(°/oo)
27.2
33.6
33.8
29.7
34.1
34.1
30.0
33.9
33.9
32.2
34.0
34.0
33.1
33.2
33.6
29.6
30.7
33.6
21.9
33.3
33.6
!).().
(rng/1)
10.4
10.1
9.5
9.3
9.1
9.2
9.2
9.4
9.5
9.4
9.2
9.3
9.0
9.0
9.1
9.2
9.0
9.9
9.8
8.8
9.2
Turbidity
(FTU)
5.5
3.8
42.0
4.8
3.8
5.2
4.6
5.3
11. 0
2.1
2.8
6.1
2.0
2.3
2.8
4.3
6.5
13.0
8.0
12.0
27.0
Station
Station Depth Depth
USD 3 8.5 Surface
Middle
Hot torn
DS13 12.0 Surface
Middle
Bottom
CS02 9.5 Surface
Middle
Bottom
CS13 10.5 Surface
Middle
Bottom
DC01 9.5 Surface
Middle
Bottom
DC02 7.3 Surface
Middle
Bottom
DCO) 7.5 Surface
Middle
Bottom
CHOI 7.5 Surface
Middle
Bottom
CII02 9.5 Surf. ire
Middle
Hot Lorn
Temp .
(C)
26.8
26.5
26.7
27.0
27.2
27.1
27.4
26.7
26.8
27.8
27.3
27.0
27.8
27.0
27.1
27.3
26.8
26.7
27.5
27.0
27.4
29.0
29.0
28.9
27. 1
27. 1
26.9
Salinity
C'/oo)
33.7
34.4
34. J
34.5
34.5
34.5
32.3
34.2
34.3
27.9
33.7
34.3
34.3
34.3
34.4
32.6
34.3
33.8
34.2
34.2
34.1
12.1
13.5
14.5
33.6
37.7
34.1
n.o.
(l»ti/ 1 )
5.9
5.5
5.8
5.8
5.8
5.7
5.8
5.5
5.6
5.9
6. 1
6.2
6.1
6.0
5.8
6.2
5.8
5.5
5.9
6.0
6.0
7V.2
6.4
5.6
5.8
5.5
5.4
Turblill ly
(1 HI)
2.(>
J.8
24.0
6. 7
l.fl
1.6
4. 7
5.H
H.8
5.6
1.6
4.8
». J
).7
5.4
2.9
11.0
1 1.0
2.8
J.5
8.8
7.7
10.0
21). (I
5.8
1 ).()
28.0
I
OJ
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
-32-
Table 2 Maximum concentrations of various substances measured in
sediment, water, and tissue samples collected from the
vicinity of the Georgetown DMDS.
PARAMETER
Oil and grease
Nitrate as NOj
Nitrite as N02
Total Kjeldahl
Nitrogen
Soluble Phosphorus
as P04
Total Phosphorus
as P04
Total Organic
Carbon
Cadmium
Arsenic
Chromium
Nickel
Copper
Iron
Lead
Mercury
Zinc
Pesticides
Total resolved
Hydrocarbons
SEDIMENT
CH02
CS13
CHOI
DC01
DS03
DC 01
DC 01
ND
CS13
ND
ND
DC03
DC03
ND
DS08
CH02
ND
CS02
687 mg/kg
533.33 mg/kg
106.28 mg/kg
994 mg/kg
1.72 mg/kg
53.13 mg/kg
0.810% mg/g
1.47 ug/8
4.02 yg/g
15,473 ug/g
0.61 ug/g
41.04 ug/g
8.95 ug/g
WATER
DS,DC 4.0 mg/1
NA
NA
NA
NA
NA
NA
CS05 7.1 mg/1
CS05 92.8 mg/1
CS05 5.3 mg/1
ND
ND
ND
ND
ND
CHOI 265 mg/1
ND
CHOI 416.63 mg/1
TISSUE
ND
•ND
ND
ND
ND
ND
ND
ND
DS
ND
ND
DS
ND
ND
ND
DS
ND
ND
2.34 mg/g
9.65 mg/g
53.61 mg/g
ND - Not Detectable
NA - Not Analyzable
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
Tdble 3
Comparisons of geocheiulcal analyses of sediments for Georgetown and Charleston Harbor areas.
CHANNEL
PCUs Aroclor
1254 Mg/g
DDE Mg/g
TOC X
Oil and
grease mg/kg
Nitrate as
N03 mg/kg
Nitrite as
N02 mg/kg
Total Kjeldahl
Nitrogen mg/kg
Soluble Phosphorus
as POA mg/kg
Total Phosphorus
as P04 mg/kg
Cadmium |ig/g
Arsenic MR/g
Chromium Mg/g
Nickel Mg/g
Copper Mg/g
Iron Mg/g
Lead Mg/g
Mercury Mg/g
Zinc Mg/g
ND
ND
0.086 -
< 6 -
57.97 -
10.0 -
40 -
1.20 -
8.43 -
< 0.
1.38 -
1.25 -
<0.5 -
<0.1 -
5,075 -
< 0.
0.27 -
9.60 -
0.549
687
278.57
106.28
546
1.63
34.72
1
1.44
14.9
9.95
2.49
15,473
5
0.51
41.04
GEOKCETOW
CONTROL
ND
ND
0.047 - 0.529
8 - 206
15.44 - 533.33
0.34 - 8.04
29 - 266
0.231 - 1.01
8.11 - 15.44
< 0.1
0.41 - 1.47
<0.1 - 8.50
< 0. 5
<0.1
2,175 - 8,308
< 0.5
0.11 - 0.38
7.64 - 22.89
N D H D S
DISPOSAL
ND
ND
0.057 - 0.120
< 6 - 105
17.55 - 32.66
0.21 - 81.31
20 - 807
0.849 - 1.72
5.82 - 11.26
< 0.1
.36 - 1.36
1.16 - 2.46
<0.5 - 5.89
<0.1 - 1.02
2,180 - 4,227
< 0.5
0.08 - 0.61
5.38 - 11.14
IEC *
DOWN CHARLESTON
CURRENT ODMDS
ND 0.000492
ND 0.000027 - 0.00005
0.060 - 0.810 0.05 - 12.5
< 10 - 507 9 - 63
50.77 - 392.0 NA
3.96 - 27.45 NA
31 - 994 NA
0.304 - 1.20 NA
5.92 - 53.13 NA
<0.1 NC
1.07-1.38 NA
1.22 - 9.05 NA
< 0.5 NA
<0.1 - 4.02 NA
3.608 - 11,558 NA
< 0.5 NC
0.21 - 0.55 0.001 - 0.005
7.83 - 23.77 NA
SCWMRD **
CHARLESTON
HARBOR
ODA
NA
NA
< 1.0
< 10 - 22
0.2 - 1.9
0.1 - 0.2
1
OJ
< 100 - < 1000 ™
1
< 0.1 - 2.2
700 - 13800
< 0.1 - 0.4
1.1 - 10.0
7.0 - 38.0
< .5 - 7.3
8.0 - 27.0
1,800-6,800
< 0.5 - 2.5
.06 - 1.13
6.0 - 28.0
* Interstate Electronics Corp. (EPA, 1982)
** South Carolina Wildlife and Marine Resources Dept. (1979)
NA - Not Analyzed
ND - Not Detected; Detection Limit is 50 ppb.
NC - Not Comparable; differing analyses.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
A
<*
!v9*
7/
j*
,*»'
,e'
.^o^
4e<>
,r
^
-->T
l?%
^N
:«»
M^
?// fo
w
V c, \
f /
/^/////
^^^ / / 4^*
/x *
At? /
/ ^ & % ^
^
-20m^/
-------
I 1
KNOWN OR rnoiAiu HARO-IOTTOM AREAS
VJ SHAltOW, STRONG REflECTOR O.S-kHz DATA)
R/V FAY 017-10* SEISMIC IINES O.S-kHi DATA)
GEORGETOWN
•$ \
34*00'
•roo-
•O'OO'
79-00'
78*00'
Figure IB Hard-Bottom Areas of the South Atlantic Bight (Identified
from side-scan sonar and seismic profile records)
Source: Henry and, Giles, 1979
Source: Final EI3 on Savannah, Charleston, and Wilmington ODMDS designation
- 33'30'
- 33*00'
- 32*30'
32*00'N
77*00'W
CO
-------
-35-
SHRIMP (BROWN, WHITE, PINK) AND,
INSHORE FISHERIES (BLUE CRAB, SHAO,
STRIPED BASS)
WILMINGTON J
MIDDEPTH COMPLEX (SNAPPER, PORCY)
!-3 DEEPWATER COMPLEX (GROUPER,
SiJ3 PORCY, TILEFISH)
K?1 SCALLOPS
GEORGETOW
CHARLESTON
- 3TN
78'W
Figure 19 Fishing Areas in the South Atlantic Bight
Source: BLM, 1978
Source: Final EIS on Savannah, Charleston, and Wilmington ODMDS designation
-------
-36-
Shriap
66Z Whit*
33Z Brown
~ '
laator*
(Slltt crab,
Sturgeon, cad othar
Scat*
Oyster tad CLj» Grooad"
Ch*rt«r Bo«t and
Figure 20 Location of commercial and recreational fisheries resources:
iDavis, et al., 1980; 2BLM, 1981; 3Moore, 1980; ^Myatt, 1978;
SSmith, 1983.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
MURRELLS INLET
%
Q&WNYAH BAY
m
. . CHARLESTON HARBOR
ENDANGERED SPECIES
O B*ld £•«!«
Brown Pelican Rookery
Loggerhead Turtle Keating
(Moderate)
Loggerheed Turtle
(Hign)
^ Red Coekaded Woodpecker'
k'^//] Shorrnoee icurgeon
MARiaE HISTORICAL FEATURES
• "Sir Robert Peel" 1
Umuaed archeologlcal'
Site
10
SCALE
rss
0
Noutieai
Figure 21 Location of endangered species and marine historical features:
iDavis, et al., 1980; 2BLM, 1981; 3SCWMKD, unpublished.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
10
-37-
-------
• CHARLESTON HARBOR
Figure 22 Location of preserves, wildlife centers, beaches and ports:
iDavis, et al., 1980; 2BLM, 1981.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-38-
-------
-39-
IV. Environmental Consequences
In discussing the environmental consequences of the proposed
action (designation of the existing ODMDS) and alternatives,
it is necessary to recall that the designation process only
recommends ocean sites at which suitable dredged material may
be dumped. Actual impacts would accrue when the disposal
action occurs according to Section 103 of MPRSA. It is
reasonable, therefore, to think of designation as the first
step of a two step process. The impacts of disposal might be
considered a consequence of site designation. No impacts due
to dumping of highly toxic or otherwise unsuitable material
will be considered, since such disposal is not permitted by
law.
The eleven specific site selection criteria required to be
considered by the regulations are presented in the Final EIS.
The evaluations of the proposed ODMDS at Georgetown and mid-
shelf and shelf break alternatives are generally consistent
with that analysis. Further site specific environmental
analysis based on the SCWMRD study is provided in the following
sections.
The Existing ODMDS
The most notable finding of the detailed study of the existing
ODMDS by SCWMRD was that 30 years of disposal failed to
produce any observable long-term effects on the bottom contours,
sediments, water quality, or benthic communities (See pages
Chapter II of this Supplement). No significant long-term
consequences are predicted for the continued use of this site
if present dredging practices are continued.
Concern has been expressed by SCWMRD for the shrimp
and sturgeon fisheries and the endangered loggerhead turtle
and shortnose sturgeon, in regard to the location of ocean
disposal sites. However, data does not exist to support
a conclusion of significant adverse impact from continued use
of the existing site. These are mobile species able to avoid
direct impact. Also, the site is not large enough to block
or greatly hinder sturgeon and shrimp movement into or out of
the estuary nor is the site close enough to shore to obstruct
female turtle movement on to beaches to nest. The sturgeon
tend to gather at the coastal inlets during February and
March, with a commercial fishing season from February 15 to
April 15. It is possible that disposal operations during
this time at the ODMDS could disrupt this fishery. No hard
bottom habitat, artificial reefs or shellfishing ground would
be impacted by use of this ODMDS. With the possible exception
of larval shrimp, none of these species would likely be
-------
-40-
affected even by disposal of finer-grained materials at the
existing site. (See discussion of short-term water quality
impacts below.)
Short-term impacts are normally limited to smothering of
sessile aquatic organisms by burial, temporary increases in
turbidity and the probable introduction of pollutants into the
water column. The existing ODMDS was chosen to avoid hard
bottoms and other areas where the effects of burial would be
severe. The absence of significant impacts attributable to
dredging on the sediments and the benthic organisms of the
Georgetown ocean site, after repeated use, is evidence that
these effects are short term.
Evaluation of the hydrological data collected at the ODMDS
site indicates tidal influence on water circulation to be
greater than ocean currents, which create predominantly
southerly water movement along this area of the coast.
Although dredged spoil is expected to be mostly sand fractions,
finer particles will be suspended in the water and move toward
the beaches or into the inlet under flooding tide conditions.
This is not considered a significant adverse impact. It
should not present conditions adverse to bather health, but
could increase water turbidity at South Island beaches.
Closest major recreational beaches are 15 miles north of
Winyah Bay. Normal tidal and ocean currents are not strong
enough to cause significant shoreward movement of the heavy
deposits of dredged spoil. Only extreme storm events provide
sufficient energy to redistribute the mass of spoil. The
SCWMRD study found no evidence of mounding at the ODMDS.
Short-term effects on water quality were discussed generally
in Chapter 4 of the Final EIS incorporated by reference, from
which the following is taken: "Wright (1978) concluded that
at most dredged material sites increases in turbidity persisted
for only a few hours, and, in addition, 'storms, river
discharge, and other natural phenomena resulted in turbidity
increases of much greater magnitude than those associated
with disposal'." This conclusion appears particularly
applicable to the Georgetown ODMDS where dredged material is
sandy, river discharge is extremely high (Figure 16), tidal
currents that flush Winyah Bay are strong, and even normal
wave action reaches the bottom sediments. Commercial trawling
also creates high turbidity levels, in addition to the direct
mortality of shrimp and incidental catches (including loggerhead
turtles). Because of the area in which trawling takes place
and its duration from May through December, its impacts on
turbidity and substrate disturbance are probably much greater
than those due to ocean dumping.
-------
-41-
Detectable quantities of ammonia are sometimes released during
disposal, but due to the sandy nature of the entrance channel
material and the strong water mixing, any release would likely
be small and quickly diluted. Samples from the channel area
have been tested by Jones, Edmunds, and Associates (1979) for
a recent harbor entrance channel dredging project. Using
chemical bioassay, and bioaccumulation techniques; and chemical
analyses of sediments, water and whelk tissue by SCWMRD the
tests show the dredged material to be unpolluted relative to
surrounding sediments and waters. No significant increase in
dissolved metals, chlorinated hydrocarbons, or other contami-
nants is anticipated if only the entrance channel dredged
spoil is placed in the ODMDS.
The likelihood of affecting cultural resources is remote at
any of the ocean dump sites but is less at the existing ODMDS,
since there is no accumulation of dredged material and little
chance of burial. Areas to be dredged are required to be
surveyed prior to project activity.
A nearby historical feature, the "Sir Robert Peel" wreck is
located just inshore of the ODMDS (Figure 21). Spoil disposed
on the proposed site will not impact this resource.
Disposal in the existing ODMDS near the entrance channel
would consume less energy than disposal in the alternative
sites, and would be the least costly.
There are no known indirect impacts or conflicts between
Federal, or state laws and regulations, or local land use
plans and any of the alternatives except the upland and
inland water sites, which were rejected. Permanent designation
of the existing ODMDS site (the proposed action) is believed
to be consistent with South Carolina's coastal management
program based on correspondence of May 30, 1979 from Duncan
C. Newkirk of the South Carolina Coastal Council to William
H. Brown, District Engineer for the Corps at Charleston
relative to a previous dredging project at Georgetown.
ALTERNATIVES TO THE PROPOSED ACTION
The Nearshore Area, Other than the ODMDS and "Control" Site
Designation and disposal of entrance channel material at
other nearshore sites would, at a minimum, result in the same
short-term environmental impacts described for the existing
ODMDS. In some landward locations, disposal of dredged
-------
-42-
material might cause significant adverse impacts on loggerhead
turtles, shellfish, or other nearshore resources (See Figures
20-21). At other less studied nearshore sites, the impacts
of disposal would be similar to those at the existing ODMDS
but may be more severe. For example, disposal in an area
with different currents or wave action might result in build-
up of the material or alteration of a dissimilar substrate,
with consequent impacts on benthic organisms. Dumping in
nearshore waters which are not as frequently subjected to
heavy suspended sediment loads as is the existing ODMDS might
affect plankton or other biota in the water column differently.
Hauling dredged material even small distances drastically
increases consumption of fuel and dredging costs ($175,000
per mile for a typical contract).
Mid-Shelf and Shelf Break Regions
The one sure consequence of designating and using a mid-shelf
or shelf break ODMDS in the South Atlantic Bight would be a
major increase in dredging costs and consumption of energy due
to the extra hauling distance. If one considers 450,000
cubic yards to be a typical dredging contract effort and
applies the figure of $0.35/c.y. for hauling material to the
mid-shelf and shelf break boundaries listed on page ,
the increase for an average contract would be between $1,000,000
and $7,000,000 for a mid-shelf site and between $7,000,000
and $10,000,000 for a shelf break site. Additional costs
would be required to rig most hopper dredges for operation in
offshore waters. The number of accidents and the severity of
damage to men and equipment would probably increase, since
the hopper would be exposed to a wider range of weather ana
operating conditions and would not always be able to move
quickly to a safe harbor.
Environmental impacts due to ocean dumping at mid-shelf or
shelf break areas would be similar to those generally described
for the nearshore areas but could be more severe. The chance
of inadvertently dumping dredged materials on sensitive hard-
bottom areas and the chance of altering bottom sediments are
greater. The consequences to benthic organisms of altering
sediment texture at mid-shelf and shelf break areas are
largely unknown.
None of the alternatives, with the exception of inland water
site use, would result in the consumption of natural or
depletable resources, other than fuel. However, as described
above and in Chapter 2, fuel consumption to transport dredged
material to mid-shelf, shelf break, inland, and some nearshore
sites was a factor in the rejection of some sites.
-------
-43-
Upland Disposal Sites and "Waters of the U.S."
Because of the high costs, equipment difficulties and
unavailability of suitable sites, these alternatives were
quickly dropped from consideration. A brief discussion of
the rationale for their rejection is found in Chapter 2 and
is not repeated here. Beach enrichment (deposition) adjacent
to the inlet is not desired by the landowners. This alternative
would increase potential adverse impact to the loggerhead
turtle spawning on the beaches.
Mitigative Measures for the Proposed Project
Use of the proposed ODMDS must comply with the EPA Ocean
Dumping Regulations and Criteria. Channel sediment material
is tested prior to dredging to determine compliance with the
criteria. The tests include toxicity to aquatic organisms
and the pollutant's potential for bioaccumulation, and the
presence of human pathogens.
Several measures are recommended which will help minimize
potential adverse environmental impacts when the Georgetown
ODMDS is used.
"Disposal operations should avoid the period of mid-
February through May, which is the time of maximum
Sturgeon activity at the inlet jetties and adjacent
coastal waters.
°Dumping of spoil should be centered within the disposal
site to minimze impact outside the designated area.
The material will spread out after being dumped. The
dredging operator should be required to provide precise
Loran-C coordinates to indicate compliance. Addition-
ally, the operator should be required to buoy the
center of the site during disposal periods to aid
visual monitoring.
"Detailed bathymetric profiles should be obtained for
the ODMDS site immediately following a disposal opera-
tion, and then again at reasonable intervals to assess
mounding and movement of the disposed sediments.
EPA is in the process of evaluating monitoring needs nationwide
for the program. There will be subsequent recommendations
for monitoring individual sites as a result of this evaluation.
In all cases, the EPA requires disposal site monitoring.
When conditions are deemed unacceptable, limitations will be
placed on the use of the site as necessary to reduce impacts
to acceptable levels.
-------
-44-
V. PREPARERS AND REVIEWERS OF THE EIS
This Supplement to the Final EIS for Savannah, Charleston, and
Wilmington ODMDS designation incorporated, directly or by
reference, data, discussions, and certain site rejection
rationale from the parent EIS where such information was
clearly applicable to the Georgetown ocean area. A list of
persons responsible for preparation and review of the parent
EIS appears on pages 5-1 through 5-3 of the EIS and is not
repeated here.
A study of the existing Georgetown ODMDS and surrounding area
was conducted by the South Carolina Wildlife and Marine
Resources Department under contract to the Charleston District,
Corps of Engineers. The purpose of this study was to collect
available information on the conditions and resources in the
Georgetown coastal area that might be affected by ocean
dumping; to make a site-specific examination of the sediments,
water, and benthic communities at the ODMDS and nearby
locations; and to assess the impacts of previous disposal at
the existing ODMDS. A list of authors follows:
Dr. Robert F. Van Dolah, Marine Scientist with SCWMRD and
Principal Investigator for the SCVvMRD study
Dr. Michael Katuna, Geologist and Associate Professor,
College of Charleston
Mr. David M. Knott, Marine Biologist with SCVvMRD
Dr. T.M. Mathews, Marine Scientist with SCWMRD
Dr. E.L. Wenner, Marine Scientist with SCWMRD
Others on the SCWMRD technical staff who contributed
significantly to the study were Mr. Martin Levisen and Ms.
Caroline O'Rourke.
The organization of the information from various sources into
the format of a NEPA Supplement was done by Stephen J. Morrison
of the Charleston District, Corps of Engineers. This task
included preparation of a Scope of Work and administration
of the SCWMRD contact, analysis and summarization of the
SCWMRD report, review of the Final EIS for its applicability
to the Georgetown Harbor ODMDS, delineation of alternative
disposal sites, and development of rationale for permanent
ODMDS selection. Mr. Morrison is a biologist and water
quality specialist on estuarine and ocean waters.
Staff in EPA, Region IV's Environmental Assessment Branch
reviewed and revised the preliminary document written by
-------
-45-
Mr. Morrison. They are:
Mr. Reginald G. Rogers, Ecologist and Region IV Coastal
Zone Management and Ocean Dumping Coordinator
Mr. F. Theodore Bisterfeld, Life Scientist and Project Officer
for EIS Preparation.
EIS Reviewers
The following federal, state and local agencies and private
organizations have been supplied the DRAFT Supplement EIS for
review.
Federal Agencies and Offices
Council on Environmental Quality
National Oceanic and
Atmospheric Administration
Federal Maritime Commission
National Science Foundation
Department of Energy
Federal Emergency Management
Agency
Army Corps
Department
U.S. Coast
Department
of Engineers
of State
Guard
of the Interior
Advisory Council on Historic
Preservation
Department of Health and Human
Services
State Agencies
S.C. Ports Authority
S.C. Coastal Council
State Historic Preservation
Office
S.C. Department of Health
and Environmental Control
S.C. Wildlife and Marine
Resources Department
State Archaeologist
State Development Board
S.C. Water Resources Commission
S.C. Division of Administration
Local Agencies
Mayor of Georgetown
Waccamaw Regional Planning and Development Council
Private Organizations
Grice Marine Biological
Laboratory
National Audubon Society
National Wildlife Federation
S.C. Wildlife Federation
Belle W. Baruch Institute
Sierra Club
S.C. Environmental Coalition
-------
-46-
APPENDIX A
Graphic and Tabular Summaries
of
Beam Trawl Data from the Existing ODMDS
"Control" and "Down Current" Sites
Collected by the
South Carolina Wildlife and Marine Resources Department
During the Winter and Summer of 1983
-------
-47-
WINTER
SUMMER
Control
Stations
Disposal
Stations
Down
Current
Stations
Combined
Stations
Decapoda
Pisces
Cnidaria
Bryozoa
Other Arthropoda
Echinodermata
2' t
Ascidiaeea
Echiurida
Figure 23 Percentage contribution, of major taxa to the species composition
of beam trawl collections.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
Table 'f Species ranked according to their frequency of occurrence (F) In > 501 of bean trawl collections.
Ar - Arthropods, Dry * Bryozoa, Ech - Echlnodernata, Mo - Molluscs, Fo - Porlfera, Al - Algae).
(Cn - Cnldarla, Ch - Chordata,
CONTROL STATIONS
DISPOSAL STATIONS
DOWN-CURRENT STATIONS
COMBINED STATIONS
Haleclua sp. (Cn) 5
Brevoortla tyrannus (Ch) 4
Ovsltpes stephenaonl (Ar) 4
Portunus glbbeell ?Ar) 4
HeabranIpors tenuls (Bry) 4
Psrsiimlttlns nit Ids (Bry) 4
Trachypenaeus constrictua (Ar) 3
Pagurua polllcarla (Ar) 3
l.lblnla eaarglnata (Ar) 3
Asterlss forbesll (Ech) 3
WINTER
Ovallpes atephenaonl (Ar)
Portunus glbbeslt (Ar)
Brevoortla tyrannus (Ch)
Trschypenaeus constrictua (Ar)
Ha lee lua ap.
S
4
3
Brevoortla tyrannua (Ch)
Anchoa •Itchllll (Ch)
Oval Ip es atepheneonl (Ar)
OvaFlpea ocellatue (Ar)
Portunus glbbeell (Ar)
Ha lee liia sp. (Cn) 3
UrophycIs reglus (Ch) 2
Etropus croasotua (Ch) 2
Scophthalaus aquoaus (Ch) 2
Symphurua plagulaa (ch) 2
Trachypenaeus constrlctus (Ar) 2
tlblnla enarglnats (Ar) 2
Membranlpora tenula (Bry) 2
Ovallpea Stephenson! (Ar) 12
Portunus glbbeslt (Ar) 11
Haleelug ap. (Cn) 11
Brevoortla tyrannus (Ch) 10
Trachypenaeus conatrlctua (Ar) 8
tlblnla esisrglnsts (Arl 7
Hcmbranlporl tenuls (Bry) 7
SUMMER
00
I
Pagurus polllcarla (Ar)
Ovsttpea stephensonl (Ar)
CsTTIsctlB trlcolor~(Cn)
plans (Ho)
Creplduls
Crepldula fornlcata (Ho)
Lelostoaus xsnthurus (Ch)
Hepstus ephelltlcus (Ar)
Portunus jtlbbeall (Ar)
Balanus venuatus (Ar)
Astropecten dupllcatua (Ech)
Melllta gulnquespertorata (Ech) 4
HembranIpora tenule (Bry) 4
Membranlpora nrborescens (Bry) 4
Prlonotus carolImis (Ch) 3
Scophthalmua aquosua (Ch) 3
Svnphurus plagulss (Ch) 3
Ovallpea ocellatua (Ar) 3
Portunus aplnlaanua (Ar) 3
Cslllnectes sspldus (Ar) 3
Squllla enpuss (Ar) 3
HydractInla echlnsts (Cn) 3
Aatrsngls satrelforala (Cn) 3
Arbncla pjinctulajta (Ech) 3
Paraimlttlna altlda (Mo) 3
Reptadconella hastIngsae (Mo) 3
l.olllguncula brevis (Mo) 3
Ovallpea atephensonl (Ar)
Prlonotua carolInua (Ch)
TAr)
Portunua
Cynosclon regalia (Ch)
Leloatomus xsnthurus (Ch)
Trschypenseus constrtctus (Ar)
Cslllnectes siull^s (ArT~
Haleclun sp. ?CnT
Hell tta qulnqueaperf orata (Ech) 3
HembranIpora tenula (Bry) 3
Hlcropogonlas undulstus (Ch) 3
Prlonotus carol Inus (Ch) 3
ScophthsTmus squosus (Ch) 3
Penaeus sitgcua aztecua (Ar)
Pagurua longlcarpus (Ar)
Pagurua polllcsrls (Ar)
Oval! pee stephensonl (Ar)
Portunus glbfaesH (Ar)
Ba lamia venustus (Ar)
Hell Its qiilnqueaperf orata (Ech)
Memb ran Ipora arborescens (Bry)
Crepldula fornlcats (JifJ 3
Baja'ejiaiiteria (Ch) 2
Larlmus fsscistus (Ch) 2
Stelllfer lanceolatus (Ch) Z
Svjnphurua plagulaa (Ch) 2
Tenaclella obi iqua (po) 2
Trachypenacua constrictua (Ar) 2
Hepatua epheTltlcus (Ar) Z
Ovallpea ocellatua (Ar) 2
Arenneua crlbrarlua (Ar) 2
Lelostoroiia xantlnirua (Ch) 2
Calllnectea apTTArT 2
Qrspyyls Elan* 0*°)
l.iill Iguncula brevja (Mo)
Sargaaaum net an a (Al)
OvalIpea stephensonl (Ar) 13
Portunus glbbesll (Ar) 11
Prlonotua carolInua (Ch) 10
Pagurua poll tear la (Ar) 10
Helllta qulnqueaperforata(Ech)10
Lelostoaus xsnthurus (Ch) 9
Bslanua venuatua(Ar) 9
Membranlpora arboreacena (Bry) 9
Crepldula fornlcata (HoT 9
Scophthalaua aquoaua (Ch) 8
Hepatua ephelltlcus (Ar) 8
Calllactls tricolor (Cn) 8
Meabranlpora tenula (Bry) 8
Crepldula plana (Mo) 8
HlcropoROtilaa undulatua (Ch) 7
Fenacus azteua aztccua*(Ar) 7
Ttachypenaeua conatrlctua (Ar) 7
Pagurua longlcarpua (Ar) 7
OvalIpes ocellatua~(Ar) 7
Lolllguncula brevis (Mo) 7
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
CO
w
>— I
o
w
fe
CO
04
w
60-1
50-
40-
30-
20-
10-
WINTER
SUMMER
STATION
Figure 2-M Number of species collected at each station by beam trawl.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
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-50-
Table 3 Species groups resulting fron numerical classification of data from samples collected
by bean trawl. (Al - Algae; Ar • Arthropoda; Bry « Bryozoa; Ch • Chordata; Cn • Cnidaria;
Ech » Echinoderoata; Mo » Mollusca; Po « Porifera).
Group A
Pilinnnus sayi (Ar)
Telesto fruticulosa (Cn)
Actiniaria A (Cn)
Asterias forbesii (Ech)
Squllla empusa (Ar)
Drophycis regius (Ch)
Busycon carlca (Mo)
Group B
irroratus (Ar)
Neopanope sayi (Ar)
Aplidiua constellatua (Ch)
Group C
Hippoporiaa contracta (Bry)
Hippaliosina rostrigera (Bry)
Centropristis striata (Ch)
Lyt echinus variegatus (Ech)
Asteroidea A (Ech*
Arbacia punctulata (Ech)
Ascropeeten duplicatus (Ech)
Busvcon canaliculata (Mo)
Group D
Reptadecnella hastingsae (Bry)
Parasnittina nitida (Bry)
PortimuS sp-tn-tmanus (Ar)
M«""hranipora tenuis (Bry)
Astrangia astreiformis (Cn)
Etropus crossotus (Ch)
Schizoporella errata (Bry)
Hippoporina verr"m i (Bry)
Chama macerophylla (Mo)
Electra monostachys (Bry)
Group E
Micropogonias undulatus (Ch)
eribrarius (Ar)
Pagurus longlcarpus (Ar)
Cynoscion regalis (Ch)
siailis (Ar)
Hepatus epheliticus (Ar)
Lariaus faseiatus (Ch)
Penaeus aztecus aztecus (Ar)
Stall if er lanceolatus (Ch)
Sclerodactyla briar etis (Ech)
Sargassum natans (Al)
Aplidiun sp. (Ch)
Bh"
-------
BEAM TRAWL:STATION GROUPS
SIMILARITY
8
8
8
8
8
8
8
8_
8
8
8_
W
W
8
W_
W
W
W
W
W_
W
8
W
W
W
W
C80B
DC01
C802
C800
DC02
D806
D808
_DC03
D8T3
C813
D8_13
~D813
C802
D803
_D80d
C8O9
DC02
0809
DC01
_D803
C810
C811
DC03
D811
C804
C813
O.B
Group Season Station i
0.0
0.4
0.2
L_
-0.2
-0.4
i
en
Figure 25 Normal cluster dendrogram showing station groups formed
using the Jaccard similarity coefficient and flexible
sorting of beam trawl collections.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
BRA If TRAWL:NODAL DIAGRAMS
SIMILARITY
-0.1 -0.« -0.4 -O.t
SITE GROUPS
CO
OONBTANOY
W«r» Hl«h£0.r ^IgJ Lo»2.O.I
Hlgh^O.t | | Vwy lo«<0.l
SITE GROUPS
I 284 B
FIDELITY
V«y Hlghi.4 iili^j
| | V«ryLov
-------
-53-
APPENDIX B
Graphic and Tabular Summaries
of
Benthic Grab Samples From the Existing ODMDS,
"Control" and "Down Current" Sites
Collected by the
South Carolina Wildlife and Marine Resources Department
During the Winter and Summer of 1983
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-54-
Number of species representing each of the major macroinvertebrate taxa in grab samples
from control, disposal, and "down current" sites. (* indicates a taxon that was probably
represented by more species, than indicated due to uncertain or incomplete identifications),
CONTROL
STATIONS
Taxa
Polychaeta
Amphipoda
Pelecypoda
Gastropoda
Decapoda
Echinodermata
Isopoda
Mysidacea
Sipunculida*
Cumacea
Anthozoa*
Bryozoa
Hemichordata*
Scaphapoda
Nemertina*
Oligochaeta*
Turbellaria*
Nematoda*
Ostracoda*
Tanaidacea
Ascidiacea
Brachiopoda
Cephalochordata
Stomatopoda
Echiurida
Pycnogonida
Phoronida
Total
Number of
Species
116
37
30
31
29
7
4
5
4
4
3
2
2
2
1
1
1
1
1
-
1
1
1
1
1
1
1
288
Rank
1
2
4
3
5
6
9.5
7
3
9.5
11
13
13
13
17
17
17
17
17
-
23
23
23
23
23
23
23
DISPOSAL
STATIONS
Number of
Species
94
22
30
12
16
5
6
4
3
1
2
3
1
-
_ 1
1
1
1
1
1
1
1
1
1
-
1
™
210
Rank
1
3
2
5
4
7
6
8
9
20.5
11
10
20.5
-
14
14
14
14
14
20.5
20.5
20.5
20.5
20.5
-
20.5
™
1XJWN CURRENT
STATIONS
Number of
Species
58
16
16
7
12
2
1
3
1
1
1
1
1
-
1
1
-
1
1
-
1
-
1
-
1
-
*
127
Rank
1
2.5
2.5
5
4
7
16
6
16
16
95
16
16
-
9.5
9.5
-
9.5
16
-
16
-
16
-
16
-
~
COMBINED
STATIONS
Number of
Species
152
42
42
36
33
9
7
5
4
4
3
3
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
357
Rank
1
2.5
2.5
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
------- OCR error (C:\Conversion\JobRoot\000002PF\tiff\20006Y94.tif): Unspecified error
-------
-56-
NUMBER OF SPECIES
NUMBER OF INDIVIDUALS
Control
Station*
Disposal
Station*
Down
Current
Station*
Combined
Station*
Polychacta
PaUeypoda
Amphipoda
Gaatropoda
Bryosoa
Dacapoda
Aaeidiacaa
Sehiaodcraata
Ncmatoda
laopoda
Oth»r»
Figure 27 Percentage contribution of major taxa to the number of species
and number of individuals in grab saaples from control, disposal,
and "down current" sites.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
Table 8 Relative abundance of the ten doaitnant apeciea ft each alte during each aeaaon. FT Indicates the feeding type of each species
(C • carnivore, D - deposit feeder. O - oanlvore, S - suspension-feeder) and the numerical values represent the percentage
contribution of each species to the total nu»ber at that aite In a particular Reason.
CONTROL STATIONS
FT S Spec lea Nave
FT
DISPOSAL STATIONS
X Species Naaie
DOWN-CURRENT STATIONS
FT S Specie* Name
COMBINED STATIONS
FT X Spec lea Name
S
S
D
S
7
C.D
S
C
D
0
13.9
6.8
6.1
5.7
4.7
3.7
3.2
3.0
2.6
2.3
Enata directua S 40
lunulata S IB
Craaalnel
E_«ISi catharlnentii S 5
Etlchthonlus. braslllenala S 3
Folygordlldae A S3
Neoiatoda S 2.7
CraaalnelU •artlnicenala D 2.3
Nenertines C,D 1.6
Aapidoalnhpn Boanoldl T 1.4
Exoapne dlapat 0 1.3
WINTER
Enata directua S 60.9
Craaelnella nartlnencla T ll.l
Pleuroroerla trldentata. C.D S.I
Sabellurla vulaarU C 2.1
Fvuri viliaii D 1.5
Craaalnella lunulata C 1.4
Acanthohauatorlua •tllal S 1.2
Nematoda 0 1.2
Polygordlldae A C 0.8
Aauldoalulum yoanpldl D 0.8
directua
Polygordlldae A
Nematoda
Nenert inea
Polycirrue exi»lua
HephtYfl plcta
Sabellaria vulgar la
Ajiclnua depreeauB
Clvcera ep. A
Herlnldea untdeiitata
S
S
S
?
D
S
C.D
C
D
S
26.2
6.8
5.0
4.6
3.8
3.7
3.3
2.5
2.0
1.8
Enals direct us
Crasalnells nart Inlcensla
Craaalnella Itinulata
Polygordlldae A
Bates catharliienalB
Erlchthonlua braslliensla
Nematoda
Nemer tinea
Aspidoaiphon noanoldt
Pvura vlttata
SUMMER
C.D
D
S
S
D
S
S
S
D
0
J.I
6.'
6.
4 f
4.
3.
2.
2
t Neomtoda
i Hedlomaatua callfornlenais
Enala directua
Craaalnella lunulata
Paraprionoapio pinnata
Cupuladrla dona
Pyura vlttata
Craaalnella martinlcenals
Oligochaeta
Amphlodia pulchella
S
S
S
S
S
D
S
D
S
D
25.
21.
9.
3.
3.
2.
2.
1.
1.
1.
8
9
5
5
4
3
1
9
8
7
Cupuladrla dona
Craaalnella mart Inicenala
Pyura vittata
Sabellaria vulgar la
Craaalnella lunulata
Aapldoslphon goanoldi
Pleuromerla trldentata
Ollgochaeta
Diacoporella umbel la t a
MediomastuB californlenslB
S
S
S
D
S
D
D
C
S
C
26.9
6.8
6.3
5.8
2.8
2.7
2.7
2.4
2.4
2.3
Cupuladrla doma
Enala directua
Pyura vlttata
Paraprionoapio pinnata
Craaalnella mart Inicensls
Magelona phylllsae
Ollgochaeta'
Nephtya plcta
Sabellaria vulgarla
Ncmert Inea
S 17.6 Cupuladria doma
S 12.5 Craaslnella martlnlcenala
S 7.2 Pyura vittata
S 3.8 Enala dtrectue
S 3.7 Craasinella lunulata
D 3.5 Medionaatua calltornlcnata
C.D 3.5 Nematoda
0 2.6 ParaprtonoBplo plnnata
S 2.4 Sabellarla vulgarla
D 2.3 Ollgochaeta
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
-58-
*0-
30-
20-
10-
20-
18-
10-
5-
20-
-------
Table 9 Mean density of the dominant macrolnvertebrates at control, disposal, and "down current" sites during each season. Values
are the number of Individuals per 0.1 m^.
Ensls dlrectus
Crass Inella mart Inlcensls
Cupuladrla doma
Crasslnella lunulata
Pyura vlttata
Ncmatoda
Folygordlldae A
Batea cathar Inenala
Mediomastus callfornlensls
F.rlchthonlus braslllensla
Nemertlnea
Sabcllarla vulgarls
Aspldoslplion goanoldl
Oligochaeta
Pleuromerls trldentata
Amplilodla pulchella
Met harp In la florldana
Paraprlonoaplo plnnata
CONTROL
WINTER
Mean
Density
36.4
8.4
no data
17.9
3.9
9.6
12.3
15.9
5.4
15.0
7.9
2.9
6.8
4.0
0
4.1
5.5
0
STATIONS
SUMMER
Mean
Density
8.6
4.7
6.8
6.8
6.3
10.3
2.1
2.9
8.8
1.6
2.9
1.4
2.2
3.8
0.2
3.5
0.7
6.8
DISPOSAL
WINTER
Mean
Density
44.1
19.7
no data
2.9
3.4
|1.7
1.5
t
0.1
0.4
1.4
3.6
1.4
0.4
6.4
0.7
1.2
t
STATIONS
SUMMER
Mean
Density
2.1
38.0
44.8
5.9
16.6
1.8
1.6
0.8
2.9
0.2
1.6
6.0
4.0
3.3
3.7
1.0
1.5
0.2
DOWN CURRENT
WINTER
Mean
Density
49.2
0.6
no data
0.1
0.4
4.1
8.9
0.1
0.4
0.2
1.7
1.0
0.3
0.4
0
0.3
0.2
0
STATIONS
SUMMER
Mean
Density
4.1
1.7
16.5
0.2
3.9
0.3
0.5
1.1
1.0
0
1.4
1.5
0.3
1.7
0.5
0.5
0.1
3.5
C7I
U5
I
Source: SCWMRO Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
5-
4-
3-
2-
1-
0-
1.0-
.8-
.8-
.4-
.2-
0-
28-
20-
16-
10-
8-
0-
200-
180-
120-
80-
40-
0-
3800-
3000-
2800-
2000-
1500-
1000-
500-
DIVEESITYlH')
EVENNESS (J7)
SPECIES
RICHNESS(SB)
NUMBER OF
SPECIES
PER STATION
& WINTER
A SUMMER
• COMBINED
SEASONS
NUMBER OF
INDIVIDUALS
PER STATION
CONTROL
STATIONS
DISPOSAL
STATIONS
DOWN CURRENT
STATIONS
Figure 29 Average values of several community structure parameters at control,
disposal, and "down current" sites. The vertical bars indicate
the range of values for each site.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-60-
-------
BENTHIC GRAB:3TATION GROUPS
Group Seaion Station u
.7
SIMILARITY
.3 .1
-.3
3
4
8
8
8
8
8
W
W
W
W
W
8
8
8
8
8
8
8
W
W
W
W
W
W
W
8
W
C800
can
D808
D810
C813
C813
C802
C804
C800
C810
OC02
D806
C806
__P8JL?
C802
__DC09
D803
0811
OC01
DC02
0808
0813
0809
D803
DC01
DC03
cr>
i—"
i
Figure 3Q Normal cluster dendrogram of benthic grab samples showing the five
station groups formed using flexible sorting.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
STATION QROUPS.-WINTER
JETTY
JETTY
WINYAH BAY ENTRANCE
Distance i ll
-------
STATION GROUPS :SUMMER
JtTTV
WIN YAH BAY ENTRANCE
Distance . 'K|B t
:t:i GROUP 4
GROUP 6
i
CT)
to
Figure 32 Location of the summer samples among station groups resulting from normal
cluster analysis. See Figure 22 for levels of similarity.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
BENTHIG QRAB:NODAL DIAGRAM
SIMILARITY
-o.a -o.e
o
«
O
o
w
PH
CO
-0.4
-0.2 o
i i. i
B
Q
STATION GROUPS
CS(W) CS(S) DS(W) 1)8(8) L)C(W)DC(8)
CONSTANCY
Very Hlgh^O.7 fjJijilil LowlO.1
High >_0.5 | | Ver»Low<0.1
Moder«l«>.0.3
B
C
D
B
a
STATION GROUPS
CS(W) C8(S) D8(W) D8(8) DC(W)DC(8)
I
01
FIDELITY
Very Hlgh>.4 |:;!;:;i'} Lowll
High 13 | | Very Low <1
Moderate>.2
Figure 33 Inverse classification heirarchy of grab collections and nodal diagrams showing constancy and
and fidelity of species groups among the sampling sites and seasons.
Source: SCWMRD Report, "Benthic and Sedimentological Studies of the
Georgetown Ocean Dredged Material Disposal Site"
-------
-65-
Table 1'J Species groups resulting from inverse cluster analysis of grab samples. (Am » Aaphipoda;
As « Ascidiacea; Ce » Cephalochordata; Cu " Cumacea; D - Decapoda; E - Echinodermata;
I • Isopoda; M • Mollusca; My » Hysidacea; P • Polychaeta; Si • Sipunculida).
Group A
Group D
Oligochaeta
Mediomastus californiensis (P)
Neaertinea
Nematoda
Crassinella lunulaca (M)
Amphiodia pulehella (E)
Heaipodus roseus CP)
Sabellaria vulgaris (P)
Pagurus bendersoni (D)
Batea eatharinensis (Am)
Ensis directus (M)
Polygordiidae A (P)
Actiniaria
Pelecypoda
Maldanidae (P)
Unclola serrata (An)
Polyeirrus exiaius (P)
Automate evenaanni (D)
Eulalia sanguinea (P)
Plnnlia sp. (D)
Spiopnanes boabyr (P)
Nephtys picta (P)
Glycera sp. A (P)
Giveera dibranchiata (P)
Erichthonius brasiliensis (An)
Exogone dispar (P)
Metharpinia floridaaa (An)
Acanthohaustorius millsi (Aa)
Osyurostylis saiTni (Cu)
Ancistrosyllis hartaanae (P)
Clrrophorus lyriforais (P)
Goniadides carolinae (P)
Mysidopgis bigelowi (My)
Amaena trilobata (P)
Tiron tropakis (An)
Group E
Caulleriella killariensis (P)
Sigaabra bassi (P)
Aapharete aaericana (P)
Schistomeringoa rudolphi (P)
Prionospio cirrifera (P)
Owen la fusiforals (P)
Aspidosiphon albus (Si)
Drilonereis magna (P)
Paracnidae (P)
Leptochela serratorbita (D)
Tiron triocellatus (Am)
Trachypenaeus constrietus (D)
Parapionsyllls sp. A (P)
Proaysis atlantica (My)
Group F
Group B
Crepidula fornieata
-------
-66-
APPENDIX C
Ocean Dredged Material
Disposal Site Designation Criteria
Georgetown, South Carolina
-------
-67-
EPA established eleven criteria to be used in assessing suitability
of a site for dredged spoil disposal. As part of the environ-
mental review of a proposed site designation at Georgetown,
EPA, Region IV has applied the criteria which is presented
below.
1. Geographic position, depth of water, bottom topogra-
phy and distance from coast. [40 CFR §228.6(a)(1).]
The site area is approximately one square nautical
mile. Its corner coordinates are given above.
Water depth ranges from 6 to 11 meters. There are
no distinct features in the bottom topography of
the site and no evidence of any mounding of sedi-
ments from past disposal activities.
2. Location in relation to breeding, spawning, nursery,
feeding, or passage areas o_f_ 1 iving resources ir\
adult or juvenile phases. [40 CFR §228.6(a)(2).]
The nearshore coastal area off Georgetown Harbor is
utilized for breeding, spawning and nursery by many
important marine organisms. The ODMDS site is
three miles offshore from the inlet of Winyah Bay,
through which shrimp, and numerous finfish migrate
seasonally. Atlantic sturgeon are commercially
sought in and around the inlet from mid-February
through mid-May. The loggerhead sea turtle, a
species on the Federal endangered list is known to
nest on beaches adjacent to the inlet.
Being three miles offshore, the site is not close
enough to block movement of shrimp up into the
estuary or hinder the female loggerhead turtle from
nesting on the beaches. However, it is possible
that disposal operations during the sturgeon fishing
season might affect this fishery.
3. Location in relation to beaches and other amenity
areas. [40 CFR §228.6(a)(3).]
The major bathing beaches are approximately 15
miles north of the proposed ODMDS*site. Sport
fishing occurs in the area of the site, but typically
waters further offshore are fished for open ocean
species. EPA has determined that continued disposal
-------
-68-
at the proposed site will not significantly affect
recreational uses of the area waters. There are no
reefs near the proposed site. The nearest artifi-
cial reefs, that enhance sportfishing are approxi-
mately 5 miles to the northeast and approximately 9
miles to the south-southeast. No impacts to these
reefs are expected by use of the proposed site.
4. Types and quantities of wastes proposed to be
disposed of, and proposed methods of release,
including methods of packing the waste, if any.
[40 CFR §228.6(a)(4).]
The material to be dumped at an offshore disposal
site will result from dredging the entrance channel
to Winyah Bay. An annual average (based on the
years 1973 through 1984) of 286,666 cubic yards of
dredged material has been dumped at the proposed
site.
Sediments dredged from the entrance channel are
predominantly sand.
Hopper dredge is the type of vehicle for dredging
and transport of the dredged material.
Dredged material may not be approved for ocean
dumping unless it meets the criteria in 40 CFR Part
227.
5. Feasibility of surveillance and monitoring. [40
CFR §228.6(a)(5).]
The United States Coast Guard is not currently
conducting surveillance at the existing site;
however, surveillance would be relatively easy
because the site is only three miles offshore.
Either shore-based observers or day-use boats could
be used for surveillance. Monitoring is feasible
at the proposed site.
A monitoring plan for the site has not yet been
developed. However, environmental monitoring will
be done for as long as the site is used. Reports
of the monitoring operations will be made available
to the public through notice in the FEDERAL REGISTER,
Such reports will be made at least at five-year
intervals, and more frequently if evidence of
significant adverse environmental effects is found.
-------
-69-
6. Dispersal, hori zontal transport and vertical mixing
characteristics of the area, including prevailing
current direction and velocity, i£ any. [40 CFR
§228.6(a)(6) .]
Predominant nearshore currents move southerly during
summer months and northerly in winter months. The
area of the proposed ODMDS is under tidal influence
particularly during ebbing flows. Current velocities
measured at the proposed site were weak to moderate
ranging from 0.1-0.9 knots during winter and 0.1-
1.1 knots during summer sampling periods. Tidal
currents appear to have a stronger influence on
waters in the vicinity of the proposed ODMDS site
than nearshore ocean currents. Both hydrologic
forces will cause the dumped sediments to spread in
most any direction over a yearly period.
Significant Long-term accumulation or mounding of
dredged material has not been detected at the
existing site by high-resolution profiling at the
disposal site conducted before and after disposal
operations. Storm producing wave action affecting
the entire water column are believed to cause
spreading of the sandy sediments dumped previously
at the site.
7 . Existence and ef f ec_ts of current and previous
discharges and dumping in the area (including
cumulative effects). [40 CFR §228.6(a) ( 7).]
Annual dredged material disposal has produced no
significant adverse effects on the water quality at
the proposed site. Changes in water quality as a
result of disposal operations have been of short
duration (minutes) and have been confined to
relatively small areas. No major differences in
finfish and shellfish species or numbers were found
in the recent SCVvMRD survey within and adjacent to
the existing site.
Past use of the existing site has created no
persistent mounding or other disturbances of benthic
infauna and demersal fish assemblages. Diversity
and density of benthic communities within the
disposal site are comparable to nearshore control
sites that were surveyed. No adverse, cumulative
affects are evident from previous disposal operations.
-------
-70-
8. Interference with shipping, fishing, recreation,
mineral extraction, desalination, fish and shellfish
culture, areas of special scientifie importance and
other legitimate uses of the ocean. [40 CFR
§228.6(a)(8) .]
Shipping, fishing, and recreational activities
occur in the vicinity of the existing site. Previous
dredged material disposal operations are not known
to have interfered with these activities. No
resource development occurs in the immediate vicinity
of the existing site, such as mineral extraction.
Although the waters and considerable land area
surrounding Winyah Bay are used for environmental
study, the existing site and immediate coastal
waters are not of special scientific importance.
Aquaculture activities presently do not occur in
the vicinity of the disposal site.
9. The existing water quality and ecology of the site
as determined by available data or by trend assessment
or baseline surveys.
Investigations of the dredged material disposal
site have indicated that previous disposal has had
no significant adverse effects on water quality
(e.g., dissolved nutrients, trace metals, dissolved
oxygen, or pH). Freshwater runoff via foinyah Bay
results in varied salinity and high turbidity near
the site. Trace contaminants in the water were
shown to be within or below ranges noted elsewhere
along the coast. Many metals were below detection
limits as were PCbs and all pesticides tested.
Fish and shrimp dominate the nekton community
adjacent to the existing site, and species are
typical of those reported from the coastal waters
all along the South Atlantic Bight. Several of
these species are commercially and recreationally
important, including the brown and white shrimp and
various fishes. The surgeon fishery is particularly
important at the inlet to Winyah Bay.
Bottom sediments were medium to coarse grain sands
at the site. Comparison of pollutant content of
these sediments with other data near the site and
elsewhere along the coast indicated that the site's
sediments can not be considered polluted.
-------
-71-
The benthic infauna community is characteristic ot
coastal medium to coarse sands in the vicinity of
the proposed site. Species diversities are variable
from season to season, with the summer diversities
quite high. Combining the summer and winter season
sampling data, the proposed ODMDS ranks between the
control site and the "down current" site for species
diversity, species richness, number of species per
station and numbers of individual organisms.
Results of the study suggest that there have been
no long-term effects on the benthic infauna at the
proposed site resulting from past disposal acitivity.
Surveys there did not detect the development or
recruitment of nuisance species.
11. Existence at. or _i£ close proximity to the site of any
significant natural or cultural features of historical
importance. [40 CFR §228.6(a)(11) . ]
No historical features are known to exist within
the proposed site. The "Sir Robert Peel" wreck is
located just inshore of the site.
The existing site is believed to be compatible with
the criteria used for site evaluation, at reasonable
costs. EPA considered whether it would be preferrable
to designate a deepwater site. For the following
reasons, EPA believes that the existing site is the
preferrable site for the disposal of dredged
material. These factors are discussed in greater
detail in the EIS.
The existing site is 3 nautical miles offshore from
South Island whereas a mid-shelf deepwater site
would be more than 25 nautical miles from shore
(Criterion 1). Disposal costs and energy consumptin
involved in use of a deepwater site would be
significantly greater than for the proposed site
due to greater transportation demands.
Dredged material has been dumped at the proposed
site, and the effects of disposal have been
insignificant. the bottom is sand, and the site is
not located near sensitive hardbottom marine habitat.
Deepwater sites have not been used for dredged
material disposal, and the environmental impact is
uncertain.
«U. S. GOVERNMENT PRINTING-OFFICE: I 984-7','.-- M 1.
------- |