Title : Ice wharves at McMurdo <
Type : Antarctic EAM
NSF Org: OD / OPP
Date : May 23, 1992
File : opp93064
INITIAL ENVIRONMENTAL EVALUATION FOR THE PROPOSED REPLACEMENT,
OPERATION, AND DECOMMISSIONING OF ICE WHARVES AT
MCMURDO STATION, ANTARCTICA
May 1992
National Science Foundation
Division of Polar Programs
Washington, D.C.
CONTENTS
1. INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . .1
2. PURPOSE AND NEED FOR ACTION . . . . . . . . . . . . . . . .1
3. ALTERNATIVES, INCLUDING THE PROPOSED ACTION . . . . . . . .3
3.1 DESCRIPTION OF THE PROPOSED ACTION . . . . . . . . . .3
3.1.1 History of the Use of Ice Wharves at McMurdo
Station . . . . . . . . . . . . . . . . . . . . . . . . . . .3
3.1.2 Construction . . . . . . . . . . . . . . . . .6
3.1.3 Use and Maintenance of the Ice Wharf . . . . 11
3.1.4 Disposal . . . . . . . . . . . . . . . . . . 12
3.2 ALTERNATIVES TO THE PROPOSED ACTION . . . . . . . . 13
3.2.1 Use of a Steel Barge or Barges . . . . . . . 13
3.2.2 Construction of a Permanent Pier . . . . . . 14
3.2.3 Ice Dock Alternative. . . . . . . . . . . . . 14
3.2.4 No-Action Alternative . . . . . . . . . . . . 14
4. AFFECTED ENVIRONMENT . . . . . . . . . . . . . . . . . . 15
5. ENVIRONMENTAL CONSEQUENCES AND MITIGATION . . . . . . . . 16
5.1 PROPOSED ACTION . . . . . . . . . . . . . . . . . . 16
5.2 ALTERNATIVES TO THE PROPOSED ACTION . . . . . . . . 17
5.2.1 Use of a Steel Barge or Barges . . . . . . . 17
6. FINDINGS . . . . . . . . . . . . . . . . . . . . . . . . 19
7. LITERATURE CITED . . . . . . . . . . . . . . . . . . . . 21
8. LIST OF PREPARERS . . . . . . . . . . . . . . . . . . . . 23
ACRONYMS AND ABBREVIATIONS
ASA Antarctic Support Associates, Inc.
cfm cubic feet per meter
cm centimeter or centimeters
ft foot or feet
GPM gallons per minute
IEE Initial Environmental Evaluation
in. inch or inches
kg kilogram
L liter or liters
lbs pounds
m meter or meters
min minute
NSF National Science Foundation
NSFA Naval Support Force Antarctica
PCBS Polychlorinated biphenyls
SEIS Supplemental Environmental Impact Statement
USAP U.S. Antarctic Program
INITIAL ENVIRONMENTAL EVALUATION FOR THE PROPOSED REPLACEMENT,
OPERATION, AND DECOMMISSIONING OF ICE WHARVES AT
MCMURDO STATION, ANTARCTICA
1. INTRODUCTION
The National Science Foundation (NSF) is responsible for the
U.S. Antarctic Program (USAP) that supports a substantial
scientific research program in Antarctica, often in cooperation
with other countries. The USAP maintains three year-round
stations in Antarctica�McMurdo Station on Ross Island (Fig. 1),
the Amundsen-Scott South Pole Station, and Palmer Station on the
Antarctic Peninsula. McMurdo Station is the major base for
providing logistics support to numerous scientific field camps on
the continent each austral summer. Logistic and operational
support are provided by the Department of Defense [the Naval
Support Force Antarctica (NSFA), U.S. Army, and U.S. Air Force],
the U.S. Department of Transportation [U.S. Coast Guard], and a
civilian contractor [currently Antarctic Support Associates, Inc.
(ASA)].
An important component of USAP logistic support for the
continent, and for maintenance of safe conditions for personnel
is the annual resupply by ship of supplies and fuel that arrive
at McMurdo in late January and February. Since 1976, cargo and
fuel have been offloaded using an ice wharf located in Winter
Quarters Bay. In 1991, NSF published a Supplemental
Environmental Impact Statement (SEIS) on the U.S. Antarctic
Program (NSF 1991) that contains a brief description of the ice
wharf and its use at McMurdo Station. This Initial Environmental
Evaluation (IEE) is tiered to the SEIS and has been prepared to
address specifically the potential environmental impacts of the
construction, use, and periodic replacement of the ice wharf.
2. PURPOSE OF AND NEED FOR ACTION
Docking, loading, and offloading ships at McMurdo Station,
Antarctica, require a large stable platform capable of supporting
heavy equipment and cargo and providing a safe working
environment. Since 1973, ice wharfs have been constructed to
serve this function. An ice wharf has a finite life and must be
replaced periodically (Voelker et al., 1991, NSF 1991). In
February 1991 the ice wharf at Winter Quarters Bay developed
several cracks extending below the water
Figure 1. McMurdo Sound and vicinity.
line that rendered the wharf inoperable for the 1992�1993 season.
Replacement of a new ice wharf is therefore needed to accommodate
ships that visit McMurdo Station during one period each year to
offload cargo and fuel and load wastes and other materials that
are to be returned to the United States or New Zealand for
disposal or reuse. The resupply ship and the fuel ship are
accommodated normally between the end of January and the first
two weeks of February each year. Ice wharves may continue to be
replaced in the future. In order to resupply McMurdo Station
during the 1992�93 season, construction of a new ice wharf, or
planning for another alternative, must be initiated during the
austral winter.
The purpose of this IEE is to evaluate potential
environmental impacts that would result from the construction,
operation, and eventual disposal of ice wharves. The specific
actions are (1) construction of an ice wharf during the winter
season, (2) use of the ice wharf, and (3) eventual disposal of
the ice wharf when its useful life is over.
3. ALTERNATIVES, INCLUDING THE PROPOSED ACTION
The proposed action is to periodically construct a new ice
wharf using methods that have been developed since the early
1970s. In addition to construction of new wharves, this IEE also
evaluates the use of ice wharves for offloading cargo and fuel
and for other ship visits that occur in late January and February
of each season and their eventual disposal at the end of their
useful lives.
Alternatives to the proposed action that are evaluated in
this IEE are (1) to replace the ice wharf with one or more steel
barges, (2) replace the ice wharf with an ice dock, (3) construct
a permanent pier, and (4) the no-action alternative of not
replacing the ice wharf, and offloading cargo and fuel from an
anchored vessel directly onto the sea ice at some distance from
the Station.
3.1 DESCRIPTION OF THE PROPOSED ACTION
3.1.1 History of the Use of Ice Wharves at McMurdo Station
The ice wharf has been located in Winter Quarters Bay along
the Hut Point peninsula (Fig. 2). The ice wharf is used to dock
vessels for unloading cargo and petroleum products and
Figure 2. McMurdo Station facilities.
for loading wastes and other materials to be retrograded to the
continental United State (or other nations when permitted).
Different designs of this wharf have been tried over the years.
A history of the development of docking facilities is summarized
here and in Table 1.
Table 1. History of docking facilities at McMurdo Station,
Antarctica
Year
Pre
1964
Cargo was unloaded from ships on the annual sea ice
about 10 km from McMurdo Station and moved to shore by
sled.
1964
Shorefast ice at Hut Point served as a wharf.
1972
A steel and wood dock was constructed but destroyed by
storm.
1972
A 7.6 � 15.2 m non-floating ice dock was built for the
1973 season.
1973
A large floating ice wharf (140.2 m seaward face and
193.5 m landward face) was built. It was 6.1 to 8.8 m
thick and extended 51.8 m from shore.
1976
A second ice wharf (about 250 m on the seaward face and
about 365 m on the landward face) was completed. It
was 6.4�7.6 m thick and extended about 90 m from shore.
1980
A third ice wharf was completed. It's dimensions are
not documented, but it was 4.6 m thick.
1983
A fourth ice wharf was built similar in dimensions to
the 1976 wharf. Thickness of the wharf at the
beginning of the summer season was 4.6 m. Ice was
added to the wharf in 1984, 1987, 1988, and 1989. Ice
thickness probably exceeded 9 m by 1989.
1990
A fifth ice wharf was built similar in design to the
1976 wharf but only 3.0 to 3.7 m thick. About 1.5 m of
ice was added in 1991.
1992
A new ice wharf is proposed that would have a seaward
face of about 198 m and shoreward face of 256 m. It
would extend about 99 m from shore and be 6.1�6.7 m
thick.
During the International Geophysical Year and for several
years thereafter cargo was offloaded onto the annual sea ice
about 10 km from McMurdo and hauled by sled train to Ross Island.
In 1963�64, Winters Quarters Bay was opened by ice breaker and
the shore ice was used as a natural wharf, eliminating many
hazards associated with transporting cargo across the sea ice.
This natural wharf deteriorated and was replaced by a steel and
wood dock structure between 1968 and 1972. This dock was
destroyed in March 1972 by small icebergs driven into Winter
Quarters Bay during a storm. The first ice dock, 7.6 � 15.2 m,
was built in the winter of 1972 and was used in conjunction with
two short piers for the January�February 1973 shipping season.
In 1973 a large floating ice wharf was built that lasted through
the 1975 season. A second large ice wharf, built in 1976, lasted
until 1979 and was replaced during the winter of 1980 (NSFA
1981). The third wharf was built in 1983, was repaired annually,
and lasted until 1990. In February 1990, this pier was towed 25
km to sea for disposal (NSFA 1990). The last ice wharf built in
1990 (Fig. 3) broke into three large pieces in February 1992, was
cabled together, and, then was resurfaced for the 1991�1992
season. It was removed from Winter Quarters Bay in March 1992.
3.1.2 Construction
Table 2 indicates the type and quantities of materials used
during this construction process. Table 3 lists the construction
equipment to be used. Lessons learned from the construction and
operations of previous wharves indicate that the procedures
detailed in the Engineering Manual for McMurdo Station (Hoffman
1979) should be followed in constructing a new ice wharf. The
basic guidelines are as follows:
(1) Design the wharf to be a fully floating structure to reduce
stress due to partial grounding.
(2) Restrain the wharf from drifting out of position by use of
bollards and cable lash-up.
(3) Oversize the wharf to allow for retreat of the seaward ice
face due to the loss of ice in the annual trimming and
straightening of the ship docking face.
(4) Reinforce the wharf with steel cables so if it does crack it
will hold together until it refreezes. Set the cables back
from the face by about 30.5 m so they do not interfere with trimming.
(5) Begin construction soon after 61 cm of sea ice has formed so
the ice is thick enough to support equipment and there is
enough time to achieve the required thickness of the wharf
(6.7�7.9 m) before it is used in January.
Figure 3. Schematic (not to scale) of 1990 ice wharf in
Winter Quarters Bay, McMurdo Station, Antarctica.
Table 2. Types and quantities of materials used during
construction of the ice wharf.
Type
Use
Amount (estimate)
Seawater
To make ice
170,340,000 liters
1" steel cable
Reinforce wharf
6400 m (2134
m/layer)
2" steel pipe
To enable steel
cable to be looped
107 m
1.5�2.0" steel pipe
Flooding gauges
91 m
1.9 cm or smaller
gravel and fines
Provide a non-slip
working surface on
wharf
4,500�5,000 yd3
(3760�4180 m3)
JP-8 gas
Fuel for the
construction
equipment, lighting
pumps, and heated
building
18,900 liters
Mogas
Gasoline for
automotive and
similar engines
9,500 liters
(6) Emphasize extra safety precautions when building the wharf
such as incorporating a "buddy" system for all workers
because of the slippery surfaces and difficult working
conditions.
The following procedures may be modified slightly since each
reconstruction must be specifically adopted to the existing
conditions.
Construction would begin after the sea ice reaches 61 cm in
thickness. Snow would be bermed to a depth of about 30 to 60 cm
along the perimeter of the wharf (Fig. 4) in order to contain
water that is pumped onto the ice. Two 5680 L/min (1500 GPM)
pumps would be used to flood the wharf surface with about 10 cm
of water. Steel pipe, 3.8 to 5.1 cm (1.5 to 2 in.) in diameter
would be used as flooding gauges. The 10.2 cm of water is
expected to freeze in about 24 hours which would allow another
10.2 cm layer to be added. When the ice thickness of the wharf
reaches 1.5 m (Fig. 5), steel cable would be woven around a
series of 5.1 cm (2 in.) steel pipes that are set into drilled
holes. An area of about 61 � 15.2 m would be reinforced and
would require about 2130 m of cable. Flooding would continue to
build the ice up for another 1.5 m and a second layer of cable
would be added. A third layer would be added when the ice is 4.6
m thick. The finished thickness of the wharf is planned to be
6.1 to 6.7 m. Lighting for the
Figure 4
Figure 5
Table 3. Equipment to be used in construction of the ice
wharf.
Type
Function
2 1500 GPM
pumps
Pump water to flood the wharf for ice
formation.
2 graders and
a D4 and D6
dozer
Make snow berm and spread surfacing materials.
2 forklifts
Make poles and pipe.
Grid roller
Compaction of surface materials and eliminate
air bubbles in freezing ice.
Trencher
Help create a straight smooth surface on the
seaward facing ice.
Tracked drill
(auger)
Drill holes for bollard setting.
Tracked drill
Drill holes for gauges and cable loop pipe.
Compressor 600
cfm
Provide compressed air for air driven
equipment.
construction period would be fixed on 9.1 m wooden utility poles.
Shorter sections of these poles would be used for bollards.
These would be placed into the ice by drilling and blasting
holes, placing the poles and freezing them in place with a
mixture of fresh water and mineral fines.
Before the wharf is used for offloading a ship, a 15 to 20
cm layer of 2 cm and smaller gravel (friable pumice) taken from a
borrow area would be applied to the surface. The seaward face of
the ice wharf would also be trimmed and straightened by trenching
and/or blasting the ice. About 20 people would be involved in
the construction which would probably begin in May and finish in
October.
3.1.3 Use and Maintenance of the Ice Wharf
The wharf is used primarily for docking a tanker that
unloads fuel in late January and a cargo ship that unloads
supplies and loads materials for retrograde and transport back to
the United States or New Zealand. The ice breaker that arrives
in early January and research vessels that may visit McMurdo also
use the ice wharf.
At the end of the austral summer season, the surface
material would be removed and stored for reuse the following
season. At least on one occasion, a storm wet the surface
material and froze it in place. Ice was than added on top of
that material and new surface material was added. Use of the
wharf may result in spills of fuel, antifreeze, oil, or hydraulic
fluids. The surface material generally absorbs such spills. Any
noticeable spills would be cleaned up and drummed for retrograde.
Before removal the NSFA would collect twenty (20) 10.0-gram
samples of the surfacing materials from random locations on the
wharf. The samples would be stored frozen in pre-cleaned, 8-
ounce, clean wide-mouth glass bottles for analysis of possible
contamination. An action plan for the sampling of earth-fill
materials will be provided by NSF to NSFA.
Annually the seaward face of the ice pier becomes eroded by
wave action and discharge of water from ships that dock at the
wharf. In the past, discharge of coolant water from docked ships
has greatly eroded the wharf face. A wharf face curtain and a
metal deflector shield would be incorporated into the design to
minimize erosion of the ice. These precautions would be taken to
extend the useful life of the ice wharf.
The eroded face of the wharf would be trimmed by explosives
and trenching. Holes 10.2-cm wide would be drilled in a single
line, to a depth of 3.7 m on 0.9 to 1.2 m centers. Each hole
would be loaded with a uniform charge of 3.7 m of 4,064 gr/cm
(1600 gr/in.) detonation cord (7,010 m/sec velocity). The line
would be about 5 m back from the seaward face. After blasting,
the ice breaker would clear the fractured ice face and remove it
from the bay. The 30.5 m of ice in front of the reinforced area
of the ice wharf (Fig. 3) would provide the surface for trimming
over the life of the wharf (approximately 4 years or more).
The wharf could be subjected to much stress due to wave
action, grounding, and ice breakout by the icebreaker. The cable
in the 61 m by 152 m area (Fig. 4) would be designed to prevent
the wharf from coming apart if cracks develop. Part of the
maintenance schedule would be to allow the cracks to refreeze
(heal) and then to form additional ice on top to strengthen the
wharf. It is assumed that ice would be added each year.
3.1.4 Disposal
When the ice wharf deteriorates (e.g., becomes too small or
fractured), it would be towed to sea and released to melt with
the annual sea ice. Prior to disposal all surfacing material has
been, and would continue to be scraped off; and all structures
that can be detached would be removed. Removal of the ice wharf
is essential because it would prevent another wharf from being
built due to space limitations and would be an obstacle to ships
entering the bay.
3.2 ALTERNATIVES TO THE PROPOSED ACTION
3.2.1 Use of a Steel Barge or Barges
An alternative to reconstructing the ice wharf is to replace
it with a relatively permanent structure that would be towed to
McMurdo and located at the site of the previous ice wharfs in
Winter Quarters Bay. This structure would consist of one or more
steel barges that could be fabricated for or purchased by the
USAP and towed to Antarctica. The following discussion of the
steel barge alternative is based primarily on a draft study
commissioned by NSF to develop a conceptual design and cost
estimate for a steel barge to replace the ice wharf at McMurdo
Station (Voelker et al. 1991).
Under this alternative, USAP would either contract to have a
new seagoing barge or barges constructed at a foreign or U.S.
shipyard or would purchase a conventional seagoing barge or
barges currently available on the world market due to the
slumping worldwide economy. The conceptual design is for a
single steel barge that would be 122 m long and 30.5 m wide. The
barge would have a draft of 4.6�6.1 m and a freeboard of 3 m, for
a maximum depth of approximately 7.6 m. The barge would be
designed for a useful life of 30 years with low maintenance. The
design waterline, while at Winter Quarters Bay, was selected as
4.6 m; this would result in a 3-m freeboard that would provide
easy access between the barge and shore. From the deck edge, the
vertical sides would extend 2.1 m down to permit easy use of
fenders between the barge, vessels moored alongside, and the
shore. At 0.9 m above the waterline the vertical hull would
change to a sloped lower hull to ensure that ice features do not
impinge on the vertical plates. A specially strengthened metal
"ice belt" of 13.9 kg-plating (30.6 lb) would extend a vertical
distance of 3 m between the 5.5-m and 2.4-m waterlines. The
standard plating used would be 9.3 kg (20.4 lbs), except for the
ice belt. The barge would have a low friction hull coating
(Inertia 160 or equivalent). The deck would be diamond patterned
steel and would be covered with about 10 cm of fill material from
a McMurdo borrow area. For winter freeze-in, the barge would be
ballasted with diesel fuel or some type of antifreeze and anti-
corrosion fluid. Once acquired, the barge could be towed to
Antarctica by the U.S. Coast Guard icebreaker that makes an
annual round trip to Antarctica or by a specially chartered
seagoing tug. The barge would be moored to the shore at Winter
Quarters Bay.
The conceptual design for building a single barge as
described above would provide a smaller work area (122 � 30.5 m)
than the 152 � 61 m area initially envisioned. The single barge
design was based on standard engineering design criteria for
length, breadth, and depth for an ocean-going barge. The Voelker
et al. (1991) study suggests that a larger work area might be
achieved by using two or four barges. Should this option be
pursued, uncertainties about ice build up between the barges and
possible twisting moments from cargo stored on one of the barges
or being transferred from one barge to another would need to be
evaluated. The single-barge wharf could be equipped with a
conveyer system for moving the cargo from ship to shore rather
than using tractors and trailers, thus compensating for the
reduced work area.
This option using steel barges could be a possible long-term
solution. It would take 2�4 years to implement, but would
require low maintenance over a 30- to 35-year expected lifetime.
3.2.2 Construction of a Permanent Pier
After the natural shorefront ice was destroyed through use
and wave action in 1968, an attempt was made to replace it with a
steel and wood panel structure. This structure was completed in
1972 but was promptly destroyed by a storm that drove ice against
the dock. It took several years to remove the debris and some
steel I beams may still be frozen in the ice near the shore. The
failure of this dock emphasizes the need for the wharf structure
to be able to withstand heavy pounding of surf and small
icebergs. Currently no permanent pier structure has been
designed for McMurdo Station, and history and recurring extreme
sea state conditions suggests this alternative is not feasible
and is not considered further.
3.2.3 Ice Dock Alternative
Building an ice dock at Winter Quarters Bay differs from
constructing an ice wharf in three major ways. First, an ice
dock is much smaller than an ice wharf. The previous ice dock
was 7.6 � 15.2 m and was a simple platform onto which containers
were lifted for removal. Because it is not large enough for
large trucks to turn around on, the handling time and unloading
time is greatly increased. Second, the work would have to take
place near the edge of the dock, thus creating a safety hazard.
Third, the dock cannot be used for mooring a ship, and thus all
lines would need to be tied to shore as well as sea anchors
deployed. Safety of the vessel would be a concern in the event
of a severe storm. This alternative is, therefore, not
considered viable and is not considered further.
3.2.4 The No-Action Alternative
This alternative would require ships to dock at the sea ice
edge some distance from McMurdo. The sea-ice alternative would
require all cargo containers to be small enough to be moved by
sled and light enough to be supported by the sea ice. The time
to offload and load the ship which currently takes 12�14 days
using the ice wharf would be greatly extended. Over 9 million
metric tons of material comes into and out of McMurdo each year
by ship. Also, this is the time when the ice is becoming thin
and safety on that ice is an overriding USAP concern. The
extended time needed to offload the ships, the constraints on
container size, and safety concerns indicate that this
alternative is not viable, and no further discussion of it is
provided here.
4. AFFECTED ENVIRONMENT
McMurdo Station (77�51�S, 166�40�E) is the major support
station for the USAP. The station is located on Ross Island and
consists of more than 100 structures, extensive storage yards, an
ice wharf, an annual sea-ice runway, a skiway, a helicopter
landing area, and other ancillary structures and features
(e.g., communications antennas and roads).
McMurdo Station is located on a southward-projecting
peninsula of Ross Island at the edge of the Ross Ice Shelf (Fig.
1). Its weather is affected by cold air drainage flowing off the
continent and ice shelf and strong cyclones that develop over the
Ross and Amundsen seas. Mean monthly temperatures at McMurdo
range from �3�C (26� F) in December and January to �28�C (�18�F)
in August. Extreme maximum and minimum temperatures of 7�C
(42�F) and �51�C (�59�F), respectively, were recorded during a
13-year period at McMurdo. The mean annual temperature is
approximately �18�C (0�F). The average precipitation is 17.4 cm
of water equivalent annually. Ice fog is common throughout the
year and sometimes reduces visibility to zero.
Man's activities at McMurdo have greatly influenced the
benthic populations of Winter Quarters Bay. Inorganic material
such as discarded equipment and general trash litter the bottom
of Winter Quarters Bay and can be found up to 6 km north to the
Cinder Cones (Dayton and Robilliard 1971). Levels of purgeable
hydrocarbons in Winter Quarters Bay sediments are as high as 4500
ppm (Lenihan et al. 1990) and are pyrolytic in origin (i.e.,
products of incomplete burning or generated by such high
temperatures as those encountered in engines). Polychlorinated
biphenyls (PCBs) with a composition identical to that of Arochlor
1260 are present in the sediment on the order of 1 ppm, a level
that would be considered high in coastal or estuarine
environments. This pollution is primarily confined to the bay
(approximately 0.1 km2 in area) because of limited circulation
and an underwater sill that partially encloses the bay and
restricts water movement and flushing (Risebrough et al. 1990).
Fill material along the shore of the wharf area has eroded into
the bay for about 8 to 9 m (Voelker et al. 1991, Appendix B).
McMurdo Sound is a deep body of water with depths reaching
500 m just 10 km west of McMurdo (Barry and Dayton 1988). Ross
Island and adjacent McMurdo Sound provide important breeding
sites for such marine mammals and bird species as Weddell seals,
Adelie penguins, and Emperor penguins. Weddell seals and
migratory skuas are the most conspicuous wildlife in the
immediate vicinity of McMurdo Station. Killer whales and leopard
seals are present in the area and prey on seals and penguins in
the vicinity when open channels form in the ice.
Because more than 97% of Antarctica's 14-million-km2 land
mass is covered by ice, exposed rock and other substrate
available to support terrestrial ecosystems is limited.
5. ENVIRONMENTAL CONSEQUENCES AND MITIGATION
5.1 PROPOSED ACTION
Environmental impacts from the construction, operation, and
disposal of the ice wharf are minimal. These consist of fuel use
and associated emissions, construction material use, disposal at
sea, collection and use of surfacing material, use of explosives,
and safety issues. The use of about 18,900 liters of JP8 and
9,500 liters of Mogas (gasoline) to run the construction
equipment and provide for the electricity for the pumps is less
than 0.01 percent of the fuel burned at McMurdo each year. The
total emissions from use of fuel at McMurdo have been evaluated
in the SEIS for the U.S. Antarctica Program and found to have
been both less than minor or transitory impacts (NSF 1991).
Construction material consists primarily of steel and water.
There are also some wooden utility poles that would be imbedded
in the wharf. Transportation of these materials to McMurdo would
result in no impacts of concern, because they represent a very
small percentage of the cargo on the resupply ship (cargo may
exceed 6.5 million metric tons). Disposal of these items at sea
as the wharf melts should result in little adverse impact. The
steel would eventually dissolve through oxidation unless it is
released to deep waters that are anaerobic. Iron released
through oxidation provides a limiting nutrient for phytoplankton
production. The utility poles would be likely to float for
several years, providing substrate for attachment of sessile
organism until they are destroyed by biological processes.
Collection and use of the fill materials is an ongoing action at
McMurdo Station, occurs only at designated borrow areas, and
results in acceptable impacts (NSF 1991). Efforts to collect all
contaminated fill on the ice wharves for retrograde should
prevent impacts due to the spread of any hazardous substances.
Safety in Antarctica is a primary concern and is given
highest priority by USAP. The ice wharf would be used only by
people with ice safety training and by qualified equipment
operators. If existing guidelines are followed, the wharf
greatly increases the safety of offloading and loading compared
to the no-action alternative of using the sea ice or an ice dock
that is too small for safe equipment operation. Use of
explosives to trim the ice face usually results in only a few
detonations of a line of charges per year. These operations
would be performed only by qualified personal with the proper
training. No safety problems from these operations have been
noted in the past or are expected in the future.
5.2 ALTERNATIVES TO THE PROPOSED ACTION
5.2.1 Use of Steel Barge or Barges
5.2.1.1 Potential environmental impacts
Experience in the Arctic has shown that steel barges can be
used successfully for long periods (Voelker et al. 1991). A life
time of 30 years or more is a reasonable expectation. These
barges generally have no special ice-strengthened features, and
operators report that "nothing dramatic ever happens as a result
of the freezing-in process." Barges that have been used in the
Arctic environment include single-skinned river fuel barges,
light-shelled seismic vessels, and double-skinned, heavily
constructed icebreaking barges. In the Arctic, the main concern
is not from the freezing-in process, but rather from the danger
of the barge being swept away with the ice during ice breakup.
Careful selection of the location for freezing-in the barges is
needed to ensure that they are securely moored.
Under this alternative, the barge would be towed to
Antarctica from its construction site or point of acquisition.
On at least one past occasion, a fuel barge was towed to
Antarctica by an icebreaker that was making its annual roundtrip
to support the USAP. There was a significant reduction in
cruising speed (from 12 knots to 2�4 knots) and transit time for
the icebreaker. Careful planning would be required to avoid
effects on icebreaker-supported activities such as refueling of
Marble Point and support of science. Possibilities for avoiding
such impacts would be to obtain a longer period of support from
the U.S. Coast Guard, possibly arrange to have two icebreakers
available, or have the barge or barges towed by a commercially
chartered seagoing tug. Environmental impacts from towing the
barge would be primarily include an increased amount of fuel used
by the icebreaker.
Although the barge or barges would be designed for low
maintenance, replenishment of the deck coating or non-skid
surface would be required on an annual basis, and repair of minor
structural damage associated with normal usage of the barge would
be needed periodically. No requirement of periodic dry docking
is anticipated, and should significant structural damage to the
barge occur, it could probably be towed to a drydock in New
Zealand for repair. Periodically, the deck surface material
would be replaced. (It is possible another type of deck surface
would be used.) Because the deck coating would be procured in
the United States and then transported to Antarctica, the current
practice of acquiring earth materials in the McMurdo area for
spreading on the working surface of the ice wharf would no longer
be required, and the already minimal impacts associated with
collection of these materials would be reduced. Environmental
impacts from maintenance activities are likely to be both less
than minor and transitory.
Heated storage would be required for the fenders used
between the barge and vessels tieing up to the wharf. Such
storage could result in impacts of building a new storage
facility, but existing storage may be available.
It is possible that some dredging would be needed in the
area where the barge or barges would be anchored. This could
create adverse impact because contaminated bottom sediments (NSF
1991) would be disturbed and perhaps remobilized. Unique benthic
communities (NSF 1991) could be disturbed or destroyed by
dredging. However, this area is already highly disturbed and the
sediments contaminated with hydrocarbons. To the extent
possible, dredging would be avoided. The barge may require
seabed anchors to keep it in place, which could also result in
disturbance of bottom sediments and communities. This potential
impact should be minimal because of the localized disturbance.
5.2.1.2 Recommendations
The following recommendations contained in Voelker et al.
(1991) should be implemented if a final design for using a steel
barge or barges to replace the ice wharf is pursued:
1. Acquire additional monthly data on ice thickness in the
immediate vicinity of and adjacent to the ice wharf site at
Winter Quarters Bay and obtain a series of ice cores in this
area to estimate ice strength. This information would be used
to evaluate if the deterioration of the ice piers is related
in part to the wastewater discharge that occurs within about
150 m of the site. More information on the bottom contours
and substrate conditions is also needed. If it appears that
dredging is needed to allow a barge to be used, a detailed
mitigation plan should be developed to ensure that any adverse
impacts from the dredging operation and the resulting spoils
are minimized.
2. Explore the acquisition and use of existing equipment from
Arctic operations. The suitability of such equipment would
need to be evaluated carefully. If an existing barge or
barges could be obtained, considerable time and expense could
be saved and additional capabilities (e.g., having cranes,
work areas, or berthing capabilities) might be possible.
3. Examine the possibility of mooring the barge farther from the
shore to eliminate the need for shore-side fenders.
4. Determine if improved methods of deploying oil spill retention
booms could be incorporated into the design of the barge.
5. Evaluate the possibility of carrying cargo on the barge when
it is towed to McMurdo. Such transport could free up space on
the annual resupply vessel for other materials, equipment, and
supplies. If schedules could be coordinated, delivery of
materials needed for the construction of the new South Pole
Station could be expedited.
6. Determine the need to develop some type of cable or chain to
draw across the bay to protect the barge from icebergs.
6. FINDINGS
The proposed construction of ice wharves at McMurdo Station
would result in both less than minor or transition impacts.
Construction of the replacement ice wharf would require steel
cables, steel pipe, and wooden poles that are incorporated into
the ice structure. Use of the wharf would require annual
collection of earth materials that would be applied to the
surface of the wharf immediately before it is used each season.
Although such materials are scraped from the wharf surface at the
end of each year and stockpiled for future use, a considerable
quantity of these materials become embedded in the ice structure
and are not recoverable. The surface of the ice wharf may become
contaminated with minor spills of petroleum products from the
operation of heavy equipment and the transfer of fuel from the
tanker. Although such spills would be cleaned up to the extent
feasible, some residual contamination could be retained in the
ice wharf structure. The useful life of the ice wharf is
uncertain. Although attempts are being made to improve the
design so that the wharf would have an extended life, history to
date indicates that an average of four years is to be expected
because the underlying ice deteriorates and cracks form to the
point that the structure begins to break up. At the end of its
useful life, therefore, the wharf would be towed to sea and
released. After the wharf is set adrift, the steel cable,
imbedded earth materials, and any contamination would gradually
be released to the ocean. The environmental impacts of this
disposal are considered to be negligible because they occur very
gradually and the resulting contamination levels, if any, would
be very small.
Reasons for ice wharf failure or longevity are not well
understood. The fewer wharves that are built the less materials
must be used and eventually disposed of. It is therefore
suggested that the following recommendations be considered for
implementation. Some of these recommendations are aimed at using
the wharves as a laboratory to increase our understanding of ice
stress and failure in order to increase the life of future
wharves, if they are built. These recommendations are:
1. Perform theoretical analysis or wave flexure in a floating ice
wharf, measurement of the ice properties in the wharf,
determination of local bathymetry, and monitoring of water
motion and ice reflection during the open-water season should
be done.
2. Use the proposed McMurdo snow and ice laboratory or suitable
institution for the study of ice wharves.
3. Evaluate the effects of the McMurdo heated wastewater
discharge on ice wharves.
A substantial effort should also be made to avoid the
cracking of the ice wharf during sea ice breakout by the
icebreakers. Historically this seems to be the single greatest
reason for wharf failure. Combinations of trenching and blasting
just prior to ice breakout should continue to be explored as
preventive measures.
Obtaining twenty (20) 10.0 gram samples of the surface
material and evaluation of those samples for possible
contamination is necessary to detect and to limit the potential
spread of any contaminants. Evaluation of these samples must be
done prior to reuse of the surface materials.
The use of a steel barge or barges to replace the ice wharf
has many potential advantages. Based on experience with barges
in the Arctic, a barge or barges may have a 30-year or longer
life. If a barge or barges were to be used for the wharf,
construction activities currently required each winter season for
the ice wharf would no longer be needed, resulting in fewer
(approximately 6) workers needed in the winter-over crew. There
is a possibility that mooring the barges to the shore at Winter
Quarters Bay would require dredging. Dredging could result in
adverse environmental impacts by release of contaminated
materials (e.g., PCBs and residual petroleum products) from the
substrate and disturbance or destruction of unique bottom
communities. The barge or barges would require low maintenance,
consisting primarily of periodic resurfacing of the deck, tanks,
and sides. Each year the barges tanks would need to be ballasted
to limit potential damage from freezing and ice. If diesel fuel
could be used to ballast these tanks, the barge would represent
an additional fuel storage facility. A risk analysis of the
potential of a fuel leak from the ballast tanks would be required
before this option was pursued. Other possibilities for ballast
are available. Use of a single barge would limit the size of the
work area and would probably require the development of a
conveyer or boom system to move cargo to and from the shore. Use
of two or four barges would require additional studies of the
effects of ice buildup between the barges and their ability to
resist damage from unequal distribution of weight during cargo
transfer. Use of steel barges is not a viable option for the
1992�93 season, but it should be given serious consideration for
implementation in the future. USAP will conduct additional
environmental review should this alternative be pursued.
Other alternatives that were considered were a permanent
pier, an ice dock, and the no action alternative of using sea ice
as a docking facility. These alternatives were dismissed because
they did not seem to be practical and/or there were major safety
concerns.
7. LITERATURE CITED
Barry, J. B., and P. K. Dayton. 1988. "Current patterns in
McMurdo Sound, Antarctica, and their implications for
productivity of local benthic communities." Polar
Biology 8:367�376.
Dayton, P. K. and G. A. Robilliard. 1971. "Implications of
pollution to the McMurdo Sound benthos." Antarctic Journal
of the United States 8:53�56.
Hoffman, C. R. 1979. Engineering Manual for McMurdo Station.
Civil Engineering Laboratory, Port Hueneme, California.
Lenihan, H. S., J. S. Oliver, J. M. Oakden, and M. D. Stephenson.
1990. "Intense and localized benthic marine pollution
around McMurdo Station, Antarctica." Marine Pollution
Bulletin 21(9):422�430.
National Science Foundation (NSF). 1991. Final Supplemental
Environmental Impact Statement for the U.S. Antarctic
Program. Division of Polar Programs, Washington, D.C.
Naval Support Force Antarctica (NSFA). 1981. Report of
Operation Deep Freeze 81, 1980�81. U.S. Navy,
COMNAVSUPPFORANTARCTICA, Port Hueneme, California.
Naval Support Force Antarctica (NSFA). 1984. Report of
Operation Deep Freeze 84, 1983�84. U.S. Navy,
COMNAVSUPPFORANTARCTICA, Port Hueneme, California.
Naval Support Force Antarctica (NSFA). 1990. Report of
Operation Deep Freeze 1989�90. U.S. Navy,
COMNAVSUPPFORANTARCTICA, Port Hueneme, California.
Risebrough, R. W., B. W. DeLappe, and C. Younghans-Haug. 1990.
"PCB and PCT contamination in Winter Quarters Bay,
Antarctica." Marine Pollution Bulletin 21(11):523-529.
Voelker, R. P., P. V. Minnick, L. A. Schultz, and J. W. St. John.
1991. Conceptual Design and Cost of a Steel Barge to
Replace the Ice Pier at McMurdo, Antarctica. Draft Report
submitted to the Division of Polar Programs, National
Science Foundation, Washington, D.C.
8. LIST OF PREPARERS
NATIONAL SCIENCE FOUNDATION, DIVISION OF POLAR PROGRAMS
Dr. Sidney Draggan, Environmental Officer
OAK RIDGE NATIONAL LABORATORY
R. B. McLean, Ph.D., Marine Biology, Florida State University;
B.A., Biology, Florida State University; 18 years'
experience in environmental assessment.
R. M. Reed, Ph.D., Botany/Plant Ecology, Washington State
University; A.B., Botany, Duke University; 18 years'
experience in environmental assessment.