Title : AMANDA science project at South Pole
Type : Antarctic EAM
NSF Org: OD / OPP
Date : June 23, 1993
File : opp93109
AMANDA Environmental Impact Assessment
AMANDA or the Antarctic-Muon-and-Neutrino-Detector-Array
would be one of the first experiments designed to do neutrino
astronomy. AMANDA's challenge is to map the skies to locate
neutrino sources, just as early astronomers used ordinary light
to map the stars in the sky. AMANDA would be a first of its kind
experiment.
AMANDA's impact on the environment can be broken down into
four distinct divisions:
1. Installation of the AMANDA photodetectors into the ice.
2. Operation of the AMANDA photodetectors in the ice.
3. Operation of the above-ice AMANDA experiment.
4. Eventually decommissioning of the AMANDA experiment.
Items 1, 2 and 4 are referred to in the text as "below-ice"
items and as such require special considerations. Item 3, is
referred to in the text as "above-ice". We will see that AMANDA
presents the same environmental considerations as many of the
experiments now running at the South Pole.
Proposed Activity
AMANDA would detect neutrinos by measuring the light signals
produced by the collision products that neutrinos occasionally
produce as they travel through the ice. Because these neutrino
collisions are exceedingly rare, very large volumes of pure,
clear, dark ice or water have to be instrumented to produce even
the most modest of results. As far as detection media go,
usually only water or ice can be found in the large volumes
required for this research. South Pole ice has three immediate
advantages over water: 1) it is a stable solid platform which
simplifies deployment; 2) it has no radioactive potassium
content; and 3) no bioluminescent life-forms that will emit light
that will disturb the photodetectors.
AMANDA's observations are best conducted in a pure-ice
environment. AMANDA would monitor these large ice volumes by
placing light sensitive detectors about 1100 meters deep into the
south pole icecap. AMANDA would be basically a non-polluting
activity. The detectors would be totally passive, and there
would be no interaction between the detectors and the ice. Light
is collected by sensitive instruments, but these instruments
require only minute amounts of power, about one watt each, and
have no waste products. The instruments would run at the normal
ice ambient temperatures. Ice clarity is of the utmost
importance for the detectors successful operation.
Holes 50 cm in diameter and 1100 meters deep would be
drilled into the ice to allow the detectors to be installed at
depths between 900 and 1100 meters. A cable carries signals from
the detectors up the hole to the AMANDA experimental building on
the surface. The holes would be drilled using hot-water. During
the drilling operation the hot-water hoses would pass through a
sheave mounted on a temporarily installed 15 meter high tower.
The hot-water technique yields a borehole 1100 meters deep filled
only with near freezing water. The impact is momentary in that
the water in the hole will freeze back in about 24-36 hours. It
is during this period that the detector modules are inserted and
allowed to freeze into the ice.
It is judged that the AMANDA surface station would present
no unusual environmental impacts, and its operation should be
like any other South Pole activity that involves people. In
fact, we plan for a largely remote operation, requiring only a
minimum technical staff to be present on site. We note that the
total impact would be slightly greater than what is currently
under way with the prototype experiments now being carried out.
Project Location
AMANDA would be located at South Pole Station. For optimal
detection, it has been determined that clear bubble-free ice with
visible light absorption lengths greater than 24 meters are
required. This bubble-free ice appears at about 800 meters depth
at the South Pole, and though other locations such as Vostok or
Dome Alpha have bubble-free ice at slightly more shallow depths
(700 meters) none of these places can offer the needed
experimental support infrastructure that South Pole Station can.
Further, if AMANDA were to be built in Greenland, then one would
have to go to depths of 1300 meters or more to find comparable
ice quality.
South pole ice is also about the coldest ice on earth with
temperatures continuously near -50 deg C, which means that the
AMANDA photodetectors would be much less bothered by thermal
noise. Again only Vostok ice is colder, about -55 deg C, and
Greenland ice is quite warm, about -31 deg C.
South Pole also offers circumpolar viewing of neutrino
sources, the unique advantage that neutrino sources never "rise-
and set" but always appear at a constant angle with respect to
the earth's rotation axis. Even a neutrino telescope, which looks
through the earth, benefits from this feature. Finally, South
Pole Station provides the infrastructure necessary to support an
experimental effort of this magnitude. Alternate locations on
the south polar icecap would require LC-130 Hercules aircraft
support and construction of life support facilities.
Current plans would call for the AMANDA array to be
approximately centered around the AMANDA/CARA building which is
located in the new astrophysics or dark/quiet sector across the
runway about 1 km grid WNW from the current station. This
location is far enough from the main base to minimize adverse
effects on observations from electromagnetic interference, but
close enough to allow safe and convenient daily access throughout
the year.
In Figure 1, we give the current site development schedule
and in Figure ,. we show the current site plan for the
AMANDA/CARA laboratory and the location of the AMANDA detectors
in their 1 + 9 configuration. The central borehole would be
located about 10 meters grid-West of the AMANDA laboratory. The
other nine holes are located in a circular pattern with a radius
of about 100 ft. This plan is shown in Figure 3. which gives a
magnified view of the AMANDA experimental area. Plans would call
for 6 of the holes to be drilled this 93-94 season, with the
remaining 4 holes being drilled during the 1994-1995 season.
Project Requirements
Current plans would call for the AMANDA project to be housed
in the top floor of the new AMANDA/CARA building, a two-story
elevated building with a 9 by 17 meter footprint, located across
the runway from the dome in what is now called the "dark sector"
or astrophysics sector (see Fig. 2). It would be extensively used
during the austral summer, and used by the winter-over operator
watching AMANDA during the austral winter[1].
Access to the site would be by foot and by vehicle. Future
plans would call for access through a new tunnel. Travel levels
of about 16 person-trips per day in the austral summer and four-
person-trips per day in the winter.
The AMANDA experiment must be protected from interference
that might be generated by other activities at the base, such as
electromagnetic interference from vehicles, and transmitters,
hence its remote location. Current plans would call for
electrical power and data and communications links to be provided
by buried power and fiber optic links connecting the astrophysics
sector to the main station facilities. The total power consumed
by AMANDA would be about 3-5 kW, and this power would be used to
run the "above-ice" data acquisition electronics in the AMANDA
building. The total amount of "below-ice" power amounts to about
1.0 watts per detector or a total power dissipation of less than
200 watts throughout the entire under-ice array.
Because the experiment is "almost" self-monitoring, only a
moderate human presence would be required at the AMANDA site.
During winter operations, only the AMANDA winter-over would be
present, while during the summer months we would expect an
average, three-four people.
Project Schedule
Current plans would call for the construction of the AMANDA
laboratory in the new AMANDA/CARA building and the drilling of
the AMANDA holes to start as soon as possible after the November
1, 1993, station opening. AMANDA is scheduled to occupy the new
AMANDA/CARA building about January 10, 1994. In this case the
experimenters would have about one month to get the experiment
set-up and prepared for 1994 winter-over operation. During the
building period, the AMANDA testing would proceed in a Jamesway
tent temporarily located just grid-West of the new building.
Hot-water drilling would be done by the Polar Ice Coring
Office (PICO) and would proceed at a rate of about one-hole per
week starting sometime after November 20, 1993. This allows for a
two-three week setup period. Plans would call for drilling six
holes this 1993-1994 season. The five holes located grid-West of
the AMANDA building would be drilled first so that the drilling
operation would not conflict with the construction of the
laboratory. The central hole near the laboratory would not be
drilled until after January 10, 1994, when work on the building
had been finished.
AMANDA's normal operation will be in a totally-passive mode.
It will not radiate any electromagnetic signals, emit any light,
or heat, or other pollutants into the environment. At times,
however, the phototubes would be calibrated with a small laser.
The laser would run for 20-30 minutes and its light would be
conducted entirely within a shielded fiber optical cables and
directed down one km deep into the ice to the phototubes. The
total power radiated into the ice will be milliwatts.
AMANDA operations should not affect any other scientific
activity at the station in any measurable way. Its personnel
would not be required to enter into any restricted areas, such as
the Clean-Air sector. The only measurable impact AMANDA will have
on the South Pole Station will be during PICO's hot-water
drilling operation. This drilling however, is being done one km
away, and almost "down wind" of the clean-air research (See Fig.
2. for details). Because AMANDA's drilling operation is estimated
to pollute the air at the same rate per day as the power-plant
for the two days/week that drilling occurs, and because is
located about two-three further away than the station's power-
plant, we believe that AMANDA's drilling operation will have no
effect on the Clean-Air Facilities operation, or any other South
Pole operations.
Impact on Environment
The South Pole Station is located on flat terrain about 3000
meters (10,000 ft.) above sea-level. It is featureless terrain
except for the man made structures already in place. AMANDA's
above-ice activities would use new structures that are in the
same character as those already there, and the impact would only
be incremental. There are no Antarctic wildlife or plant species
at this site.
Because the above-ice activities involve only electronic
signal detection and processing, they are benign or transparent
to the environment. Any toxic or hazardous substances associated
with the AMANDA operation, such as cleaning solvents used for the
maintenance of electronic equipment, would be used in only very
small quantities (measured in pints and ounces) and would be
removed from the site when their intended use is complete
following the established U. S. Antarctic Program procedures. No
such substances would be disposed of at the site.
The drilling activities require special attention. A plan
view of the hot-water drilling operation is shown in Figure 4,
and an elevation or "down-hole" view of the operation is shown in
Figure 5. Drilling each hole requires approximately 1.25
megawatts of heat and 100 kilowatts of mechanical power to drive
numerous pumps and heaters. Normally we would burn JP-8 to
fulfill our energy needs, however, during the 1993-94 season, our
energy needs could be almost entirely supplied by using some of
the 25,000 gallons of "old" diesel fuel that was the emergency
camp fuel supply [2]. As a result of using either JP-8 or diesel
fuel, there would be air pollution. There is also the potential
for spills of fuel and of the ethanol which is used as an
antifreeze to purge water from the drill system when it is not in
operation.
A study was undertaken to determine which drilling method
would most efficiently provide the 50 cm. diameter holes to a
depth of 1100 meters. Specifically, mechanical drilling
techniques were investigated since the specific energy required
to remove ice mechanically is one-hundred times less than thermal
means. However, the energy required to remove chips and provide
water to cover the instrument string is nearly equal to the hot
water technique. In addition, the cost and weight of a pipe-
driven drill system precludes its use in the current ten hole
program.
Hot water would be the drilling fluid of choice since it
matches the surrounding medium once it refreezes. Any thermal
disturbance would be dissipated in the -50 deg C ice given the
current drilling rate of five-ten holes per year. Use of other
fluids to fill the boreholes would present an unrealistic
logistics burden requiring over 50,000 gallons per hole compared
to a fuel use of 3000 gallons per hole.
The need for 1-1.25 megawatts of heat would require burning
about 40 gallons of JP-8 fuel per hour. An additional 15 gallons
per hour would be required to run the pumps and supply
electricity. Burners would be tuned and derated for altitude
(pole is at 3000 meters) to provide maximum efficiency which
would also minimize combustion by-products. Additional measures
have been taken to maximize heat transfer to the water by adding
additional coils in the heaters. High-pressure pumps would be
run with standard diesel engines.
At a drilling rate of 0.5, meters/minute it will take about
36-40 hours to drill an 1100 meter deep borehole. During that 40
hour period the fuel consumption will be about 55 gallons/hour or
a total fuel expenditure of about 2200 gallons. In a similar
period the station burns about 1900-2000 gallons (figured at a
station consumption of 1150 gallons/day during the summer months
[3], so that over the two day period need to drill one borehole,
PICO operations will burn about the same amount of fuel that the
station burned in a similar period. At a rate of one hole per
week, we find that PICO consumes 2200 gallons to the stations
8000 gallons or about 27% of the station's consumption. Over the
3and 1/2 month summer season, we find that PICO would consumes
14,000 gallons to the stations use of 115,000 gallons, so that
PICO's use would be about 12% of the station's normal usage. We
can thus say that the integrated air-pollution effect of the PICO
hot-water drilling operation is about 12% of what the station
itself contributes to the atmosphere during the austral summer
period.
The pollution from LC-130 Hercules flights can also be
estimated. At 160 flights/season with an average time on the
ground of 30 minutes, and using a burn-rate of 400 gallons/hour
we find that LC-130's burn about 30,000 gallons of fuel while
"on-deck" at the pole. This estimate does not include take-offs
and landings. When you include this contribution, you find that
PICO then adds only about 10% to the South Pole Station's total
air pollution budget.
The potential for spills would be minimized by using closed
system manifolds to transfer fuel directly from bladders or drums
to the engines and heaters. In addition, secondary containment
fixtures would be used. Pans could be placed under storage
units, generators, and in the transfer areas. In the case of an
oil or fuel spill we would follow the instructions set forth in
the South Pole Oil Contingency Plan [4].
Anti-freeze must be used to prevent water from freezing in
the hoses and heaters of the drilling system when not in use, and
to pre-heat the drill system prior to adding water. Ethanol
would be the preferred fluid in the event that some fluid is lost
during the water-purge process, since it is a naturally occurring
substance which evaporates readily even at low temperatures.
Glycols with rust inhibitors are considered unacceptable since
150 gallons are required to fill the system. Use of compressed
air to blow the system out is not an option since too much water
remains trapped which subsequently freezes.
As mentioned briefly earlier, current plans for the '93-'94
and '94-'95 drilling operation would call for us to use the
25,000 gallons of "old" diesel fuel that was the emergency camp
fuel supply. This old fuel is now of inferior quality, due to
its age, and makes its use as fuel for aircraft or emergency
generators questionable, if it is not used on-site as proposed.
This fuel would eventually have to be flown back to McMurdo at an
expense of an additional 40,000 gallons of fuel used by the
aircraft. We may also be able to use oil that is changed from
the station generators and other engines to provide oil as
required for the pump fuel mix. While oil is less than 1% of
our fuel requirements, we have to add oil to any JP-8 used to
give it some lubricant property to prevent pump failures.
Samples of oil from the station generators would be analyzed at
the McMurdo Station Laboratory or another laboratory to ensure it
meets required standards before it is combusted.
Safety and Health Concerns
We would operate within all guidelines of the regular South
Pole Station operations regarding safety for both personnel and
for the environment. Concerning the specifics of the drilling
program, several issues arise. PICO has been involved in many
hot-water and other drilling programs since 1977 without
injuries. The major safety issues are:
1. hot-water, just below boiling (90 deg C) flowing at 50
gal/min at 65 atmospheres of pressure.
2. an open-hole 60 cm in diameter with a 40 meter drop to
the water at freezing (0 deg C).
3. potential pinch points between cables and other
objects.
4. rotating machinery
5. electrical circuits
6. 15 meter high tower
Pumping water that is near its boiling point at 50 gal/min
under high-pressure has the potential of causing severe injury if
there is a catastrophic failure of a hose or other piece of
equipment in close proximity to a person. The capability of all
hoses and pressure vessels exceed operating pressures by a factor
of 6. All hoses and other hardware are rated for use at the low
ambient temperatures encountered at South Pole. Because this is
an industrial process, several safety valves, low-flow shut-offs,
and many other devices are incorporated that would shut-down the
system if temperatures or pressures get too high. Specific
"weak-points" are built into the system that provide automatic
shutdown if all else fails.
The "open-hole" issue is addressed by covering the hole with
a grate that would not allow anyone to fall through it during the
drilling operation. During periods when the grate is removed,
such as raising or lowering the drill or installation of the
detector strings, personnel working around the hole would be
wearing safety harnesses.
Potential "pinch-points" and rotating machinery would be
covered or roped off. Emergency shut-off points would be
provided near the winches and the hole.
All PICO electric circuits are restricted to 220 VAC which
does not exceed normal household operating voltages. We believe
that the normal protective circuitry combined with emergency
shut-off points at activity sites would cover this area
adequately.
Presence of a 15-meter tower would require the use of hard-
hats when work is going on overhead.
Finally, a training program for all personnel who would be
working with the drill system is a standard procedure. The nature
of this type of drill dictates that we start off with a small
system and gradually work toward the full operational system, so
everyone understands the operational procedures from first
principles. We believe the setup procedure evolves slowly enough
so that everyone receives adequate hands-on training. Half of the
drilling team would be made up of returning staff.
Recommendations for an Expanded Program
While we feel that we have prepared the most efficient and
cost-effective program for the current ten string deployment, if
the program is to continue it may be beneficial in the future to
consider the following options:
Turbo-supercharging the electrical-generator engines would
benefit performance and decrease unburned fuel in the exhaust. We
strongly recommend that this step be taken, however, the cost
would be $30,000 to $50,000 to produce a pump that can be
compared in performance to the ones we currently have. A test of
this type of unit would provide baseline data allowing a retrofit
of all existing generators operated at altitudes above 2000
meters. PICO would have to receive an "OK" to proceed by July 1,
1993 to conduct the test late this season at South Pole Station.
We recommend considering solar concentrators for supplying
heat and electricity if the project continues beyond the
presently scheduled ten holes (See attached paper) [5]. We
suggest a solar trial run using a small system first,because
solar has the greatest potential to lower the total fuel
consumption for the project, but it has a three year development
time. To pursue this program, we recommend purchasing one or two
sets of solar panels to obtain data on how to proceed with a
larger system. The estimated cost of a smaller system (800 watts
electric, and 3200 watts thermal) is about $25,000.
Finally, none of the equipment is expendable, and all
equipment would be returned and used on other projects. In the
future the system of JP-8 fired boilers would be used as a backup
for cloudy days when and if the solar option is used. Equipment
already at the South Pole would be fully used within the current
drilling scheme.
Decommissioning Impact
All of the above-ice structures and equipment that are to be
constructed or placed at the site are removable, such that at the
completion of the project, no lasting damage to the site shall
have been incurred. The impact on the environment should be
measured by the number of people present, rather than by the
nature of the experiment. The number of people, seven to eight
during the summers and one winter-over, is a small increment to
the current level of both summer and winter personnel.
It is judged that AMANDA's long-term impact on the icecap
would be negligible. The photodetectors are constructed entirely
from inert materials, and are mostly glass, with a small number
of passive electrical components (small resistors, etc.) enclosed
inside of a glass benthosphere. The amount of heat introduced
into the ice while sizable is in reality negligible when you
consider the size of the heat sink that is available during the
36 hours needed for freezeback, and the length of time between
drilling each hole--one week. Ice experts, such as Dr. Charles
Bentley, University of Wisconsin-Geophysics, have been consulted
and they assure us that the strain on the ice is minimal [6].
Transverse strains should be non-existent which means that the
cables that carry signals to the surface would not be sheared
off, and longitudinal stresses should also be very hard to
detect.
All of the below-ice structures and equipment that have been
installed at the site are also removable, but not as easily as
the above-ice structures. Water is the most benign and by far
the cheapest fluid we can use to fill the boreholes. The only
problem posed by using water in the holes is that once it freezes
the photomultiplier strings are trapped. To remove the strings
would require about four times the amount of fuel needed to
originally install them. This removal technique would also result
in four times the amount of air pollution issued during
installation. This is because the original diameter becomes the
new hole radius and the heat needed goes as the cross-sectional
area of the hole. Because the photomultipliers are 98% glass by
weight with no toxic components and the cables are polyethylene,
our recommendation would be to leave the strings exactly where
they are. South Pole ice-flow is such that in geological time-
spans (100,000 years or more) the inert string components will be
eventually discharged into the Weddell Sea through the Ronne Ice
Shelf [6].
Methods to Detect Environmental Harm
All AMANDA and PICO personnel will operate within all
guidelines of the regular South Pole Station regulations
regarding safety for both personnel and for the environment.
Recommendation
In light of the information provided above, the preparers of
this document recommend that the NSF approve a "finding of no
significant impact" from the proposed construction and operation
of the AMANDA project at the Amundsen-Scott South Pole Station.
Preparers of this Document
Robert M. Morse -- Principal Investigator, AMANDA Project
Bruce Koci -- Polar Ice Coring Office
Baxter Burton -- Polar Ice Coring Office
Terry Johnson -- ASA
Carol Andrews -- ASA
Steve Meredith -- ASA
Contributions
Mac McCatherin, ASA; John Gress, ASA; Joe Rottman, CARA; and
Chris Shepherd,
ASA
References
1. NSF/OPP Environmental Action Memorandum, Oct 26, 1992,
regarding South Pole CARA building.
2. NSF/OPP Environmental Action Memorandum, Oct 22, 1992,
"Replacement of Emergency Fuel Cache at South Pole Station".
3. Private communications, Janet Phillips, Engineer, ASA, June
1993.
4. NSF/OPP Continental Systems Regional Oil Spill Contingency
Plan, Jamestown Marine Services, Inc., Dec 14, 1992
5. Bruce Koci, PICO, ``The AMANDA Project, Drilling Precise,
Large Diameter Holes", April 1993.
6. Private communications, Prof. Charles Bentley, University of
Wisconsin, 1993.
Figure Captions
1. South Pole Science Construction Schedule. Schedule for the
period Jan 93 to Jan 97.
2. South Pole Site Plan. Plan gives the relationship of the new
AMANDA/CARA building at the Astrophysics Site to the present
South Pole Station. AMANDA is located approximately 1 km grid
NNW of the Dome.
3. An Enlarged Presentation of the AMANDA/CARA Site. Shown is
the 1 + 9 AMANDA borehole configuration, with the central hole
about 25 ft. grid West of the AMANDA building. Also shown about
300 ft. grid WEST of the AMANDA building is the area in which
PICO will set up its drilling equipment. The Jamesway shown is a
temporary structure to house the AMANDA project until it can
occupy the building on January 10, 1993.
4. PICO's hot-water drilling layout. Site plan shows the
locations of the cable and hose winches, the down-hole sheave
complex, and the pumps, heaters, and hot water storage
facilities.
5. PICO's hot-water drilling layout-elevation view. View shows
position of down-hole pumps, water reservoir, and cable sheaves.