Title  : Sea water desalination system, McMurdo
Type   : Antarctic EAM
NSF Org: OD / OPP
Date   : May 18, 1993
File   : opp93104


           INITIAL ENVIRONMENTAL EVALUATION
REPLACEMENT OF THE SEA WATER DESALINATION SYSTEM,
MCMURDO STATION, ANTARCTICA

              National Science Foundation
               Office of Polar Programs
                    Washington, DC

                     May 18, 1993

1.  INTRODUCTION

     The U.S. Antarctic Program (USAP) is proposing to
replace the Sea Water Desalination System at McMurdo
Station, Antarctica, during the 1993-1994 season.
Since 1986, the potable water supply at McMurdo Station
has been produced using a multi-stage flash
distillation system at the current location of Building
198.  This system has been in continuous operation
since its installation, and has in recent years shown
signs of increasing deterioration due to corrosion and
scale formation requiring significant increases in
maintenance.  The Supplemental Environmental Impact
Statement (SEIS) on the USAP (NSF 1991) identified and
discussed the technologies used at USAP stations and
field camps to produce potable water.

     The purpose of this Initial Environmental
Evaluation (IEE), the equivalent of an Environmental
Impact Assessment, is to evaluate in more detail
potential environmental impacts that might result from
the installation, operation and maintenance at McMurdo
Station of various potable water supply technologies.
This IEE is prepared by USAP in compliance with the
National Environmental Policy Act, the Antarctic
Treaty, and the Protocol on Environmental Protection to
the Antarctic Treaty (the Madrid Protocol) adopted by
26 countries in 1991.

1.1  BACKGROUND

     The National Science Foundation (NSF) is
responsible for the USAP that supports a substantial
national 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, the Amundsen-Scott
South Pole Station, and Palmer Station on the Antarctic
Peninsula.  McMurdo Station is the major base for
providing logistic support to numerous scientific field
camps on the continent each austral summer.  Logistic
and operational support is provided by the Department
of Defense (Naval Support Force Antarctica, U.S. Army,
and U.S. Air Force), the U.S. Coast Guard, and a
civilian support contractor (currently Antarctic
Support Associates, Inc).

     An essential component of USAP logistic support is
the provision of a safe and healthful potable water
supply for personnel working at McMurdo Station.  Also,
potable water is used in connection with the scientific
research supported by the USAP.  In a 1992 evaluation
of the shell corrosion and status of operation of the
multi-stage flash distillation system now in place and
in operation, conducted by the original vendor, Beaird
Industries, Inc., the inspector commented that repairs
would be required within three years.  More recent
evaluation suggests that repairs would be required
sooner.  This has prompted the NSF's Office of Polar
Programs to direct Antarctic Support Associates, Inc.
(ASA) to conduct a design and procurement review for
replacement water plant equipment.

     Any new desalination plant would be sized to
provide potable water for an austral summer population
of about 1300 people and an austral winter population
of about 350.  A consumption rate of 208 liters per
person per day (270,628 L/d) would be used to determine
the capacity of the new Water Plant.  The new Water
Plant would have a total austral summer capacity of
approximately 360,000 L/d, based on a capacity load
factor of 90%.  Potable water consumption during the
austral winter would be approximately 73,000 L/d.  The
specific location of the proposed activity would be
Building 198, the Primary Distillation Water Plant,
McMurdo Station, Antarctica (77deg51'S, 166deg40'E).
(See Figure 1).  No alternative locations were
considered.  An alternative location would require the
construction of a new facility to house any new
desalination equipment.  The existing facility was
constructed for this specialized function.

1.2  PHILOSOPHY OF THE U.S. ANTARCTIC PROGRAM IN
     MINIMIZING ENVIRONMENTAL IMPACTS

     Reducing human impacts on the antarctic
environment is a major goal of the USAP.  This
philosophy of environmental protection embodies notions
of human safety as well as support of scientific
research of high value and quality.  The operating
philosophy of the USAP (Draggan and Wilkniss 1992)
recognizes the potentially profound impacts that its
presence and its activities can have upon Antarctica.
This philosophy acknowledges the importance of the
various components of the human environment, the
antarctic environment, and the interactive processes
that give structure to those environments.  The
philosophy goes further in affirming that USAP will use
all practicable means and measures to foster and
maintain Antarctica's natural conditions while
promoting and supporting antarctic scientific endeavors
in a manner that is safe and healthful for USAP
participants.

     The USAP's operating philosophy is based upon
several broad, yet reasonable and practical,
assumptions.  The assumptions are that:  (1) the
Antarctic Continent can be viewed, in the main, as a
closed environment; (2) inputs to, and outputs from,
the operating environments of the USAP (that is, its
stations, field camps and vessels) can be controlled;
(3) while all human activities entail some measure of
change or impact to the environment, those changes and
impacts can be minimized, mitigated, or controlled;
and, (4) effective minimization, mitigation, and
control of change or impact depends on
information-intensive approaches that foster early
consideration of potential changes or impacts.

<++++++++++Figure 1++++++++++>

     In keeping with this philosophy, this IEE focuses
on actions or changes to program activities that might:
(1) reduce human impacts by reducing the need for
antarctic personnel and non-science support operations;
and (2) foster environmentally compatible use of such
natural antarctic substrates as seawater, ice and snow.

1.3  SCOPE OF THE IEE

     This IEE evaluates the impacts associated with
installing, operating and maintaining various seawater
desalination technologies at McMurdo Station.  The
intent is to provide sufficient evaluation to ensure
that adequate review of potential environmental impacts
for planned developments of potable water production
has been done and appropriate documentation prepared.
This analysis will be reviewed for future developments,
and supplemental analysis and documentation will be
prepared for such developments as necessary.


2.  THE PROPOSED ACTION AND ALTERNATIVES

2.1  PURPOSE AND NEED

     Specifically, the proposed action would replace
the existing multi-stage flash distillation unit at
McMurdo Station with a suitable alternative.  The
current system has been in a state of continual
deterioration due to corrosion and scale formation.

2.1.1  Purpose

     The purpose of the proposed action is simple and
straightforward:  to assure the provision of a safe and
healthful, year round supply of potable water for
participants in the USAP.

2.2  ALTERNATIVE ACTIONS

     Alternatives considered in this IEE follow:
(1) Multi-stage flash (MSF) distillation system;
(2) Multi-effect flash distillation system (MED) ; (3)
Vapor compression distillation plant; (4) Reverse
osmosis desalination system (the preferred
alternative); and, (5) the "No-action" alternative.
These five alternatives are discussed in the following
sections (and see Table 1).

2.2.1  Multi-Stage Flash (MSF) Distillation System

     Adoption of this system would provide, for all
intents and purposes, a replacement of the existing
system.  This system produces potable water by heating
salt water in a tubular heat exchanger using low-
pressure steam from a boiler, or from a heat recovery
system.  It then passes the hot seawater to a separate
chamber where a pressure lower than that in the heating
tubes prevails.  This causes some of the hot sea water
to vaporize or flash.  The vapor is then condensed by
cooler incoming seawater to produce pure, distilled
water.

     In a multi-stage flash distillation system, flash
distillation is carried on at a number of successive
stages (that is, the heated seawater flashes to vapor
in a series of chambers -- each at a lower pressure
than the preceding one).  The greater the number of
stages, the better the efficiency of the yield,
overall.  Flash distillation offers an advantage over
submerged-surface distillation in that the heating of
seawater without boiling causes less scale deposits.
The multi-stage flash distillation system can use steam
from a heat recovery system to heat seawater.  The fuel
required to operate a multistage flash distillation
system with a heat recovery system providing heat for
the process and a boiler to provide steam only for the
steam ejectors is approximately 1.2 Liters of fuel per
3,785 liters of water produced.  The fuel required to
operate a multistage flash distillation system when
waste heat is not used is approximately 52.2 Liters of
fuel per 3,785 liters of water produced.

     Advantages of a multi-stage flash distillation
system include:  1) a low operating cost when waste
heat is used for the distillation process; 2) the
quality of the feedwater is not as important when
compared with the reverse osmosis system technology;
and, 3) the multi-stage flash system has a high gain
output ratio (GOR):  that is, the ratio of pounds of
water produced to pounds of steam condensed in the
brine heater.

<++++++++++Table 1++++++++++>

     Disadvantages of a multi-stage flash distillation
system are a high operating cost when waste heat is not
available for the distillation process and relatively
high rates of corrosion and scale formation due to high
operating temperatures.

2.2.2  Multi-effect Flash Distillation System

     Multi-effect flash distillation systems produce
potable water by boiling seawater to create freshwater
vapor.  The vapor produced in each "effect" is
condensed on the system's cooler tube-bundle surfaces,
where it is collected as high purity distillate.  The
multi-effect evaporator employs two or more evaporator
effects, each operating at successively lower
temperature and pressure (that is, vacuum).  The
process is repeated several times, multiplying the
effectiveness of the original heat supplied in the
first effect, thereby giving the process its name.  The
first effect is heated by steam or hot water on the
inside of the evaporator effect bundle.  Incoming
seawater is sprayed on the outside surface of the tube
bundle in each effect.  In order to reuse the heat of
vaporization and condensation, the pressure in each
effect is reduced relative to the preceding effect.
The boiling occurs at lower and lower temperatures as
the feed water passes through subsequent effects.  The
distillate collects in a trough that flows from the
first effect to the last.  The multi-effect flash
distillation system can use waste heat from a heat
recovery system.  Fuel requirements for multi-effect
flash distillation with, and without, waste heat would
be about the same as that for multi-stage flash dis-
tillation.

     Advantages of multi-effect flash distillation
systems include:  1) a low operating cost when waste
heat is used for the distillation process; 2) the
quality of the feed water is not as important as for a
reverse osmosis system; 3) the multi-effect flash
system has a high GOR, and 4) the multi-effect flash
system can utilize hot water instead of steam for the
distillation process.  Hot water temperature is less
affected by changes in the power plant generator load
than steam production.

     Disadvantages of multi-effect flash distillation
systems include:  1) high operating costs when waste
heat is not available for the distillation process;
and, 2) the multi-effect flash system operates at high
temperatures that increase corrosion and scale
formation.

2.2.3 Vapor Compression Distillation Plant

     Vapor compression distillation systems use the
energy supplied by a compressor that takes vapor from
boiling seawater and compresses it to a higher pressure
and temperature -- furnishing heat for vaporization of
more seawater.  In so doing, the vapor is condensed to
yield distilled water.  Theoretically, vapor
compression is more efficient than other desalination
methods.  The vapor compression distillation system
requires a small amount of heat to preheat seawater,
and electrical energy for the compressor motor.  The
fuel required to operate a vapor compression
distillation system is approximately 15.14 liters of
fuel per 3,785 liters of water produced.

     Advantages of vapor compression distillation
systems include:  1) the operating costs are low
compared to multi-stage or multi-effect flash
distillation systems and 2) the equipment is smaller
than the multi-stage flash or multi-effect flash
distillation systems.

     Disadvantages of vapor compression distillation
systems include:  1) maintenance on compressors and
heat exchangers is greater than those of other systems;
2) energy consumption is high; and, 3) capital costs
are high.  Because of the last two reasons, vapor
compression was dropped from further consideration (see
Table 2).

<++++++++++Table 2++++++++++>

2.2.4 Reverse Osmosis Desalination System

     In the natural process of osmosis, when a seawater
solution and pure water are separated by a semi-
permeable membrane, the pure water will pass through
the membrane to the seawater solution side.  The
natural driving force is osmotic pressure.  This
process can be reversed and pure water can be made to
pass from the salt water solution to the pure water
solution.  This is accomplished through the application
of pressure to the salt water solution in excess of the
osmotic pressure:  that is, reverse osmosis.  The
reverse osmosis system does not require heat to produce
potable water.  Reverse osmosis membranes can be used
for feedwater temperatures between 1degC and 32degC but
operate most efficiently at 25degC.  As the feedwater
temperature goes down, the viscosity of the water
increases and more membranes are required for the same
feedwater flow.  Heat from a waste heat recovery system
can be used to preheat the feed water to increase
efficiency.  Reverse osmosis systems require electrical
energy for the high pressure pump.  Fuel required to
operate a reverse osmosis system is approximately 9.1
liters of fuel per 3,785 liters of water produced.

     Advantages of  reverse osmosis systems include:
1) reverse osmosis systems operate at ambient seawater
temperatures, reducing corrosion and scale formation;
2) capital equipment costs are lower; 3) lower
operating costs and energy savings when waste heat is
not available for distillation processes; 4) equipment
size is smaller; 5) equipment can be delivered in four
or five months after receipt of a factory order; 6)
start-up time for each unit is usually less than one
hour; and, 7) a steam boiler or heat recovery system is
not required.

     Disadvantages of  reverse osmosis systems when
compared with flash distillation systems include:  1)
the system's high pressure pump creates vibrations that
may require special foundations; 2) high pressure salt
water requires special materials for the system's high
pressure piping; and, 3) feedwater quality must be very
good or membranes and multi-media filters will foul and
not operate properly.  The feedwater pretreatment
system must remove colloidal materials, microorganisms,
organics, iron and chlorine from the sea water to
prevent membrane fouling and deterioration.  In
addition, chlorination as a pretreatment mechanism also
may require increased monitoring to assure that
trihalomethane formation is not occurring.

2.2.5  No Action

     The "no-action" alternative would force continued
use of the existing multi-stage flash distillation
unit.  This unit's components exhibit extensive
internal damage due to corrosion and scale formation.
The components have been repaired several times in the
past to correct leaks due to corrosion; extreme metal
fatigue, however,  makes continued repairs difficult to
execute.  The units have a very short life expectancy.
This places the population at McMurdo Station in
jeopardy of not being able to produce an adequate
supply of safe and healthful drinking water.


3.  AFFECTED ENVIRONMENT
AND ENVIRONMENTAL CONSEQUENCES

3.1  MCMURDO STATION

3.1.1  Affected Environment

     McMurdo Station (77deg51'S, 166deg40'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 pier,
an annual sea-ice runway, a skiway, a helicopter
landing area, and other ancillary structures and
features (e.g., communications antennas and roads).
During recent years, the austral winter (late February
through early October) population at McMurdo has ranged
from 100 to more than 250 people, depending on the
amount of science, construction, and renovation going
on.

     The U.S. Navy began constructing McMurdo Station
during the 19551956 season.  Because it was intended
to be used solely as a logistical support base, and
because the United States' presence was considered
expeditionary at the time, McMurdo's early development
consisted of the construction of temporary structures.
By the mid-1960s, however, it was evident that the U.S.
presence at McMurdo was to be more permanent, and the
Navy began to construct steel-frame buildings.  By the
time NSF assumed the management of McMurdo in 1970, the
station had evolved from a temporary logistical support
base into an established station responsible for both
logistic support and scientific research.  Because of
the need for facilities in which to conduct research,
in addition to those facilities required for support,
many of McMurdo Station's original temporary structures
have been replaced, and some new ones have been erected
to help alleviate overcrowding.

     Patterns of currents in McMurdo Sound were studied
by the Raytheon Service Company for consideration in
designing new wastewater outfalls and water intakes
(Raytheon 1983).  McMurdo Sound in the vicinity of
McMurdo Station is covered with sea ice that breaks up
only for brief periods in some years.  Tides follow a
13-day cycle, with daily variations in water surface
elevation ranging from about 0.1 to 1 m through the
cycle.

     Directions and speeds of currents vary greatly
among sites along the Ross Island coast and over time
during the tidal cycle.  In general, researchers
believe there is a net southward flow in the central
and eastern Sound and a northward flow in the western
Sound (Barry and Dayton 1988a).  Current meters
deployed by Raytheon (1983) showed net flows in the
immediate vicinity of McMurdo station that appear to
follow a counterclockwise eddy, with northward flows
immediately offshore.  Net flows are very low, ranging
from about 10 to 150 m/d.  More recent study of current
patterns of McMurdo's nearshore environment are on-
going, with results expected after the 1993-1994
austral summer season.  Very little flow occurs in
Winter Quarters Bay.

     McMurdo Sound is affected by the annual formation
of sea ice, and has high salinity (34 to 35 ppt) and
cold temperatures (about 2degC).  There is little
vertical variation in temperature and salinity in
winter and spring, but some stratification occurs in
summer (Barry and Dayton 1988b).

      Although water quality results of the Raytheon
study (1983) are of questionable reliability and
limited use, they indicate that:  1) high coliform
bacteria concentrations are found off McMurdo Station,
indicating that these organisms (which may indicate the
presence of sewage contamination) survive in the Sound;
2) relatively high ammonia concentrations occur both
inshore near the wastewater discharge and offshore;
and, 3) wastewater discharged from surface outfalls
tends to follow the tidal cracks around the edge of the
Sound.

     Ambient water quality characteristics are
available from Raytheon (1983) and from research
studies conducted in McMurdo Sound.  The Raytheon
values presented are from a site near the present sea
water intake jetty where samples were taken at the
surface, mid-depth, and bottom, on two different dates.
Barry and Dayton (1988) conducted hydrographic studies
of McMurdo Sound in the spring and summer.  His study
showed that nutrient concentrations are high and
uniform in the spring, prior to a summer bloom in
plankton productivity.  In the late summer, nitrate and
phosphate concentrations were about two-thirds of the
spring values, while nitrite concentrations were
several times higher in summer.  Also, this study
showed that dissolved oxygen concentrations were
uniform in spring at about 7 mg/L, and in summer were
about 8-9 mg/L near the surface.  In general, the ocean
waters at McMurdo Station can be described as cold,
nutrient rich, with relatively high dissolved oxygen
concentrations.  New water quality studies were begun
during the 1992-1993 austral summer season and,
currently, results are being analyzed and interpreted.

     Regardless of the system chosen to replace the
existing multi-phase flash distillation unit,
environmental impacts associated with construction
activities would be less than minor and less than
transitory as the new system would be installed inside
the existing Water Plant.  All work would occur within
this structure.  No building addition, requiring earth
work, would be needed .

     A portion of the skin of the Water Plant Building
would be removed so the existing desalination system
could be removed from the building.  All new equipment
would be moved into the building and assembled on-site.
The building would then be reassembled.  Little to no
waste would be created during this process and all of
the old desalination equipment would be retrograded
from Antarctica.

     Impacts on the population during construction of a
replacement facility have also been considered.  It is
anticipated that a replacement unit would be purchased
to be sent via vessel in February of 1994.
Construction would take place during the austral winter
when the population is at its lowest.

     Replacing the existing flash evaporation unit with
a like system (multi-stage or multi-effect
distillation) would require a shut-down of the Water
Plant and the use of the standby Water Plant located in
Building 126 while the old equipment is removed and new
equipment is installed.  Installation of a reverse
osmosis unit would not require the use of the standby
Water Plant -- water could be supplied to residents
with little disruption.

     The civilian support contractor's McMurdo
Operations and Maintenance staff have reviewed the
alternatives and anticipate no difference in the number
of personnel required to operate and maintain equipment
regardless of the system chosen to replace the existing
unit.  Currently, it is expected that six people are
required; nonetheless, operating staff may be reduced
to three or four.  No impacts, therefore, are expected
from an increase in station population.

3.1.2  Potential Environmental Consequences of a
Reverse Osmosis Unit

     The proposed alternative being considered is
installation.,operation and maintenance of a Reverse
Osmosis Desalination System using three reverse osmosis
units having a daily output of approximately 151,400
L/d each.

     No direct, adverse environmental impacts are
anticipated for the use of reverse osmosis, as long as
the system is properly operated and maintained.  Some
chemicals are used in reverse osmosis desalination
plants, however, that are not required with the other
alternatives.  These substances include such
sequestrants as polyacrylic acid -- to be added to the
feedwater to prevent the buildup of scale deposits on
reverse osmosis membranes; and, sodium bisulfite -- to
remove any dissolved oxygen or halogens.
Environmental contamination from chemicals -- concen-
trated corrosives -- normally used in on-site cleaning
of the reverse osmosis membranes would be precluded by
sending the membranes off-site for cleaning.  The
system would be designed, however, with a closed-loop,
cleaning option to capture substances used in cleaning
in the unlikely event that there may be a need to clean
the membranes on-site.

     Impacts on water supply during construction would
be mitigated by performing the work in phases.
Construction would begin during the 1994 austral winter
with one reverse osmosis unit being placed within the
Water Plant addition.  One unit is capable of producing
enough water to supply the needs of a winterover
population having a daily consumption requirement of
72,861 L.  Upon testing and startup of the first unit,
additional units would be set in place in the main
building as the flash evaporators are removed.  The
standby Water Plant would be readied for emergency
operation in the event of equipment failure.

The proposed site for the desalination equipment does
not serve as habitat for any significant assemblages of
antarctic wildlife.  The marine environment that would
receive its brinewater effluent does support an
abundance of marine organisms.  The effluent brine
would be discharged along with the station's wastewater
effluent.  The wastewater effluent is freshwater and
would serve to decrease the salinity of effluent brine.
No long-term aesthetic impacts are anticipated should
the proposal proceed.  There would be some temporary
aesthetic impacts associated with construction
activities, particularly when portions of the Water
Plant siding are removed to install new equipment.

3.1.3   Indirect and Cumulative Environmental Impacts

Direct and indirect costs for all alternatives have
been evaluated in a study conducted for ASA by Holmes &
Narver, Inc./1/(see endnotes)   Other indirect costs of
the proposed activity would be associated with the
proposed alternative's impacts on existing facilities
and proposed construction or development projects.

     One such project impacted by the proposed and
preferred alternative would be the human waste disposal
facility.  This facility is designed to dispose of
human waste (urine only) collected in 208-L drums.  The
facility proposes to use the hot brine from existing
flash evaporators to melt the drum's frozen contents
and to wash out emptied drums.  Reverse osmosis would
eliminate the production of hot brine produced by flash
evaporation.  The hot brine from the flash distillation
units is approximately 32.2degC.  The proposed reverse
osmosis system would use waste heat from the power
plant generators to preheat the seawater.  This would
produce a brine water with a temperature of between
1.7degC and 4.4degC.  This temperature range would be
sufficient for washing the human waste barrels and
would also suffice in melting the contents, although
this process would take more time and energy than using
hot brine from the existing flash evaporators.

     Also, the civilian support contractor is proposing
and assessing a plan for advanced wastewater treatment
at McMurdo Station.  A possible alternative under this
plan would be tertiary wastewater treatment with the
potential for effluent water reuse for either human
consumption or for growing plants hydroponically.  It
is unknown how effective reverse osmosis would be as
part of a wastewater reuse system to provide water of
sufficient quality to meet either of these
applications.

     Another indirect cost would be associated with
providing training for operators who have no experience
operating reverse osmosis units.   The present system
of flash evaporation provides a virus-free, drinking
water without any filtration or disinfection --
although McMurdo Station does employ chlorine disinfec-
tion to provide an added degree of health protection.
Reverse osmosis would not deliver the same quality of
water without disinfection.  Operators would require
additional training to ensure that the proper level of
disinfection is maintained.  Also, particular attention
must be paid by operators to biological fouling of the
reverse osmosis membranes.  Chemical and biological
fouling of the membranes can sharply reduce the cost-
efficiency of the reverse osmosis process and can cause
serious public health problems and risks.  Operators
would need to be sufficiently trained in the operations
and maintenance of the system to control fouling of the
membranes.

     The proposed, preferred alternative, reverse
osmosis, would engender several potential indirect
environmental changes near McMurdo Station.  One such
change would be the addition of cooler brine water to
the station's wastewater effluent.  The current flash
distillation unit releases to the nearshore marine
environment brinewater at a temperature between
33.3degC and 39.4degC./2/  It is estimated that the
brine water discharged from a reverse osmosis unit
would be approximately 1.7degC.  A brinewater discharge
at this temperature would further cool the wastewater
effluent and may provide increased dispersion by
reducing the rapid rise of the effluent plume to the
ice surface.   It has been pointed out, however, in the
Final Supplemental Environmental Impact Statement that
dilution of McMurdo's wastewater with desalinator brine
is expected to provide little wastewater effluent
quality improvement through increase dilution.  The
higher flow rate created by the addition of brinewater
is said to reduce the mixing that takes place as the
heated plume rises from the submerged outfall to the
surface ice.  It has been suggested, therefore, that it
may be more beneficial to use the brine water for other
purposes such as fire fighting.  Construction of a
wastewater treatment facility would greatly reduce
environmental concerns regarding the effect of the
brine discharge on the effluent dispersion.

     Another environmental change would be a reduction
in fuel usage for potable water production.  The
current flash distillation system uses an average of
26,226 L of fuel per week to generate potable water
using steam boilers (See Table 3).  Reverse osmosis has
been calculated by ASA's Engineering Division to have a
lower energy demand than flash evaporation (see
Attachment 1).  The result would be decreases in fuel
usage, in air emissions from combustion, and in
potential spills associated with fuel distribution.
Energy demand has been calculated by ASA's Engineering
Division be lessened with the use of reverse osmosis.
It has been calculated that the preferred alternative
would require a total of 98.4 Kw to operate 3 reverse
osmosis units simultaneously.  Flash evaporation has
been calculated to require 106 Kw of power to operate
two plants (see Table 1).  In addition, reverse osmosis
would eliminate the need for an average of 26,226 L of
fuel per week which is required to operate the existing
flash evaporators.

     The characteristics of the neighboring terrestrial
environment are dominated by activities supporting USAP
operations at McMurdo Station and are suitable for the
proposed activity.  The location is also close to sea
level and does not require energy to pump the effluent
to a higher elevation for discharge.  Disposal of
concentrated brinewater into the local aquatic
environment has occurred for a number of years.  In
recent years this brinewater has been hot and has been
used to dilute McMurdo Station's wastewater effluent in
order to provide a greater degree of dispersion and
increased assimilative qualities.  Environmental
impacts associated with this activity have been
presented in previous assessments and discussed in a
paper /3/ prepared by Steven Railsback of the Oak Ridge
National Laboratory; the outcomes of which revealed the
neighboring marine environment is suitable for such an
activity. Scientific studies at and near McMurdo are
not expected to be affected by adoption of the reverse
osmosis technology.  The discharge of brinewater in
combination with McMurdo's wastewater would be
monitored to predict impacts to the local environment
and to scientific research in the area.

<++++++++++Table 3++++++++++>

4.  IMPACT MITIGATION

4.1  Impact and Pollution Prevention and Environmental
Management

4.1.1  Marine Environment

     No new construction would be required, so no
construction wastes or one-time-use materials would
require disposition.  The old flash evaporation equip-
ment that would be removed from the Water Plant would
be staged and prepared for retrograde to the United
States for disposition through the military reutiliza-
tion system.  Any other construction related waste
would be treated in a similar manner.

     Protection of human health is the main
consideration regardless of the method of water
production chosen.  Flash evaporation is known to
destroy enteric viruses without the need for chemical
disinfection.  Post-chlorination has been used at
McMurdo Station as a secondary safeguard.  Tables 4A
and 4B shows the results of a study conducted during
the 1992-1993 austral summer to evaluate the presence
of enteric viruses in McMurdo Station's potable water
supply.  No viruses were detected in three separate
sampling events conducted in three separate months.

     When considering the use of reverse osmosis in
water production, several concerns were addressed to
ensure that the safest water would be produced and
delivered.  These included pretreatment of the
feedwater to prevent biological fouling of the mem-
branes and post-treatment of the permeate water.  Pre-
treatment of feedwater was considered by the Contractor
to avoid membrane biofouling.  Pretreatment approaches
typically include continuous or intermittent disin-
fection of the feedwater stream, or filtration of the
feedwater stream, to remove microorganisms and other
colloidal particles that can promote membrane
biofouling.Disinfection by chlorination, ozonation and
iodination of reverse osmosis feedwater are viewed as
the most economical methods of chemical disinfection.
Reverse osmosis membranes can be irreversibly damaged,
however, by such oxidizing disinfectants.  Where
chlorination is used, damage to the membranes may be
mitigated through dechlorination of the feedwater prior
to its entrance into the reverse osmosis system.  De-
chlorination methods include passage of the water
through granular, activated carbon or the addition of
sodium thiosulfate or biosulfate to the feedstream.

<++++++++++Table 4A++++++++++>
<++++++++++Table 4B++++++++++>

     Pretreatment using chlorination enhances, however,
the possibility of trihalomethane production due to
chlorine coming into contact with humic and fulvic
acids from the decomposing organic matter that may be
present in feedwater.  In this case, the presence of
marine phytoplankton in the source water would be of
concern.  Because trihalomethane formation was an
important concern to USAP, other pretreatment alterna-
tives were considered.

     Some studies have shown ozonation to be superior
to chlorination as a pretreatment method.  However, it
has some serious consequences.  Ozone is one of the
most powerful oxidizers known and must be handled as a
hazardous material.  In order to protect workers from
exposure to ozone, additional safety equipment must be
installed to monitor for accidental discharges in
equipment rooms.  Additional equipment may be required
to destroy excess ozone which may be present after
water's passage through a purification system's ozone
contact chamber to insure that no ozone would leak into
the ambient atmosphere during normal operations.

     The use of ultraviolet irradiation is also an
alternate method of pretreatment.  It has the
advantages of being relatively self-contained and
requires little maintenance.  The disadvantages are:
1) many bacteria are UV-resistant; and, 2) ultraviolet
irradiation does not provide a continuously available
disinfectant residual on reverse osmosis membrane
surfaces, where it is most needed.

     Prefiltration using submicron filters is also an
alternative.  However, the economics of this method has
been questioned due to the increased maintenance
required to continually keep the filters clean.  This
often offsets the advantages it has in controlling
biofouling of reverse osmosis membranes/4/.

     A reverse osmosis system maintenance firm, Argo
Scientific, has advised ASA, after reviewing the
analyses of feedwater from McMurdo Sound, that no form
of pretreatment is required.  They predict that the
system would perform well without pretreatment for
approximately three years before the membranes would
require cleaning.  Eliminating pretreatment using
chlorination of the feedwater would also eliminate the
chances of trihalomethane production.  Chlorination
would only be required to disinfect the potentially
potable permeate water to destroy pathogens and to
control microbial growth in the potable water distri-
bution system.   Following this guidance, two sets of
membranes would be purchased to use on a rotational
schedule.  Fouled membranes would be sent to the U.S.
for cleaning.  These would be replaced with membranes
cleaned off-site .  Although this method would increase
the cost of maintaining the reverse osmosis system, it
would preclude the need for importing into Antarctica
substances containing hazardous constituents (that is,
the chemicals used to clean the membranes and the need
to pretreat the water by chlorination.

     Post-treatment would consist of two injection
systems; one for chlorine injection to disinfect the
water to World Health Organization standards, and
another for sodium bicarbonate injection to maintain a
pH of 8 to 8.5.

     The proposed activity would not change surface
water flow or drainage at McMurdo.  As discussed
previously, there may be some positive impacts
associated with improved dispersion of McMurdo's sewage
effluent due to the reduction in its temperature.  The
effect of reduced wastewater effluent temperature is
more fully explained in the final Supplemental
Environmental Impact Statement.

4.1.2  Air Environment

A reduction in fuel usage, under adoption of the
preferred alternative, would positively impact the
ambient air quality by reducing air emissions.  Based
upon the calculations presented in Table 3, when
compared to a similar sized flash evaporation unit,
reverse osmosis represents an energy demand
approximately 7% less than that of flash evaporation.

4.1.3 Terrestrial Environment

Should the proposed activity be decommissioned in
future, all materials would be disassembled and
retrograded from Antarctica and the site would be
returned to as close to original condition as possible.


5.  FINDING

      The finding of this IEE is that development and
subsequent use and maintenance of a reverse osmosis
water desalination system at McMurdo Station would have
less than minor or transitory environmental impacts
(that is, no significant environmental impacts are
anticipated).

Accomplishment of the proposed action would benefit the
program.  The benefits of the proposed action include
continuing provision of a safe and healthful source of
potable water to personnel and scientific research
projects working at McMurdo.  The proposed action would
allow for:  1) removal of seawater from McMurdo Sound;
2) production of potable water and residual brine; and,
3) return of residual brine with the station's
wastewater effluent to McMurdo Sound. In all instances,
save bona fide emergencies, fouled reverse osmosis
membranes would be sent to the U.S. for cleaning; they
would be replaced with membranes cleaned off-site.


5.  LITERATURE CITED

Barry, J. 1988a.  Current patterns in McMurdo Sound,
Antarctica, and their relationship to local benthic
communities.  Polar Biology 8:367-376.

Barry, J. and P. Dayton.  1988b.  Hydrographic patterns
in McMurdo Sound, Antarctica, and their relationship to
local benthic communities.  Polar Biology 8:377-391.

Draggan, S., and P. Wilkniss.  1992.  An Operating
Philosophy for the U.S.  Antarctic Program.  Marine
Pollution Bulletin 25 (9-12):  250-252

National Science Foundation.  1991.  Final Supplemental
Environmental Impact Statement on the U.S. Antarctic
Program.  Division of Polar Programs, Washington, D.C.
(October).

Raytheon Service Company.  1983.  Report on the McMurdo
Station Water Quality Study.  Middletown, RI.

Attachment:  Memorandum From M. Lesiak/ASA to W.
Koleto/ASA on:  Power Consumption Comparison - Flash
Evaporator and RO.

6.  LIST OF PREPARERS

NATIONAL SCIENCE FOUNDATION,
  OFFICE OF POLAR PROGRAMS PANEL

  Dr. Sidney Draggan, Panel Chairperson
  Dr. Jane Dionne, Co-Chairperson
  Dr. Harry Mahar
  Mr. Frank Brier

ANTARCTIC SUPPORT ASSOCIATES

  Mr. Terry Johnson
  Ms. Carol Andrews
  Mr, Craig Martin
  Mr. William Koleto
  Mr. Matt Lesiak

OAK RIDGE NATIONAL LABORATORY
  Assessment Support::

  Dr. Robert M. Reed
  Mr. Lance B. McCold
  Mr. J. T. Ensminger
  Dr. J. Warren Webb
  Mr. Jeremy Holman

Notes

/1/  Holmes & Narver, Inc., 1993, Water Desalination
Plant Study, McMurdo Station, Antarctica, Albuquerque,
NM, February.

/2/  National Science Foundation, 1991, Final
Environmental Impact Statement, Washington, DC,
October.

/3/  Railsback, S. F.  1991.  Dispersion and Fate of
Wastewater Released from Submerged and Surface
Discharges at McMurdo Station, Antarctica.  Session on
"Measuring the Fate, Behavior and Effects of
Contaminants in Polar Environments" at the First
International Ocean Pollution Symposium.  April 28-May
2, 1991, Mayaguez, Puerto Rico.

/4/  Source:  Mittleman, Marc W. and G. G. Geesey.
1987. Biological Fouling of Industrial Water Systems: A
Problem Solving Approach. Water Micro Associates.

          <++++++++++Attachment 1++++++++++>