National Science Foundation
Office of Polar Programs
Arlington, Virginia

Environmental Document and Finding of No Significant
and Not More than Minor or Transitory Effect

Vehicle Transport of Ground-Penetrating Radar (GPR) Gear on
McMurdo Dry Valleys Ice and Snow Surfaces and
GPR-Antenna Movement on Sediment-Surfaces During Traverses

[MCDV9902.EAF]

I. FINDINGS

The National Science Foundation (NSF) has prepared an Initial Environmental Evaluation (IEE) and an Environmental Assessment (EA) as a combined environmental document for the use of one vehicle on ice and snow surfaces within the McMurdo Dry Valleys and also for the movement of radar antennas up to 1-m wide along the ground within the valleys. Both actions are in support of a ground-penetration radar (GPR) survey to be conducted by grantees working on science project, S-063, Test for Tertiary-Age Deep Fluvial Incision and Strongly Melting Valley-Glaciers in the Dry Valleys Using Ground-Penetrating Radar: A Pilot Project. The vehicle would be used to transport radar-control equipment and greatly improve the efficiency of field operations. The ground movements of GPR antennas up to 1 m wide would permit the GPR survey at the full range of frequencies requested by the grantees.

Based on the analyses in this EA, the NSF Office of Polar Programs (OPP) determined that implementation of Alternative A for each action is not a major federal action which would have a significant effect on the human environment within the meaning of the National Environmental Policy Act (NEPA) of 1969. Further, the actions are not ones which would have more than a minor and transitory effect on the Antarctic environment within the meaning of the NSF implementing requirements for the Protocol on Environmental Protection in Antarctica.

The selection of Alternative A for both components of the GPR survey provides for the use of one vehicle on ice and snow surfaces and also for the use of radar antennas up to 1 m in width. The selected action is consistent with the NSFs efforts to promote scientific investigation, provide a safe and efficient working and living environment for personnel, and protect the Antarctic environment.

/s/ Dennis Peacock10/13/98
Dennis PeacockDate
Head, Antarctic Science Section

II. PURPOSE AND NEED FOR THE PROPOSED ACTION

This Environmental Assessment (EA) pertains to conducting a ground-penetrating radar (GPR) survey of surficial sediments within the environmentally sensitive McMurdo Dry Valleys. The GPR survey is the focus of a single-season science project (S-063). In particular, two components of the GPR Survey are considered worthy of environmental assessment because of potential adverse environmental impact. One component is transportation of the GPR control equipment during surveys. The other component is moving the GPR antennas during surveys.

The purpose of the proposed project is to determine the internal composition of some selected, large morphologic features within the McMurdo Dry Valleys using GPR. The morphologic features are of two types. One is sediment covered, spur-like aprons up to 600 meters high situated below highland tributary valleys and projecting into trunk valleys. These features are understood to be made of bedrock and as such considered fluvial bedrock spurs. It is proposed to test the fluvial bedrock spur interpretation by determining sediment thickness within the apron below Denton Glacier in eastern Wright Valley using GPR. The other type of morphologic feature consists of large moraines of unknown internal composition that may be stratified. Using GPR, it is proposed to study two such moraines in central McKelvey Valley that may be associated with much fluvial and lacustrine sediment and one moraine in central Wright Valley associated with dated marine sediment. We will also conduct a GPR study of the thick moraine within eastern Taylor Valley for calibration of the GPR technique as well as to understand moraines deposited from high polar glaciers. Almost all of the sediment drilling within the Dry Valleys has been accomplished within eastern Taylor Valley in this moraine complex. Hence, this region holds the most well-known Antarctic glacial sediment sequences for calibrating GPR.

A debate is underway as to whether the Antarctic ice/climate system has been in a stable “high-polar” state since ice sheet inception 40 or more million years ago (as it has been over the last 2.5 million years), or in a “sub-polar” state characterized by considerably higher variability in precipitation, temperature, and glacier dimensions. The proposed study is needed to test these two theories. Resolution of the high-polar versus sub-polar problem is important, as it will help to indicate the sensitivity of the Antarctic ice/climate system to the considerably higher-than-present warmth that characterized the rest of the planet prior to 2.5 million years ago. The warm world prior to this period represents an important opportunity for establishing a proving ground for tuning climate and ice-sheet models such that they can better predict future change.

If the proposed study were not done, the understanding of the natural history of the McMurdo Dry Valleys would remain limited. Scientists would remain ignorant of the subsurface environment which is a major flaw given that this environment is a major part of the total Dry Valleys environment. Lack of the proposed new GPR data also would slow progress in other research disciplines, such as geocryology and biology, which require baseline information about ground-ice extent as provided by GPR data. The long-term history of Antarctica, the subject of the proposed investigation, is currently receiving significant attention as evidenced by programs such as the Cape Roberts Drilling Project. The proposed project will provide a data set that could help interpret the Cape Roberts data.

For transporting the GPR control equipment, the issue is whether a vehicle can be used at designated GPR survey-sites on lake ice, river ice, and snow banks for the purpose of towing a sled with the GPR-control equipment. The control equipment weighs about 180 lbs. and consists of a 600 W generator, a pulse generator, an oscilloscope or display module and the radar controller. The primary alternative is for four people to manually carry the equipment on a stretcher or sled that would be set down periodically.

Operating the GPR antennas involves moving them along the ground maintaining contact with the ground. On sediment (i.e. no ice and snow cover), this will probably involve minor temporary disturbance of the ground surface. We would like to use four different antennas that range in size and shape from a wand with a 50-cm square detector to 2 cables about 20 m long. As there are no alternatives to using these antennas, the issue here is mitigation.

Before presenting the methods, impacts, and mitigation for each GPR component, the areas planned for the GPR survey will be briefly described in terms of snow and ice cover.

  1. Lowermost Taylor Valley between Lake Fryxell (77°37' S, 163°11' E) and New Harbor (77°36' S, 163°51' E). There is a possibility for significant winter snow accumulation remaining in the major stream channels in this area. Additionally, there is the lake ice of Lake Fryxell.

  2. Lowermost Wright Valley between Denton Glacier (77°29' S, 162°36' E) and Lake Brownworth (77°26' S, 162°45' E). The principal ice surface here is the Onyx River which would be frozen at the time of the planned GPR survey.

  3. West-central Wright Valley between Lake Vanda (77°32' S, 161°33' E) and the Entrances to the North and South Forks (77°32' S, 161°15’ E and 77°34' S, 161°15' E). The ice cover on Lake Vanda would be the principal ice-surface. However, there may be large snow banks remaining from the winter in the North and South Forks.

  4. Central McKelvey Valley (77°26' S, 161°33' E). There is a possibility for snow banks within stream channels in this region.

Several issues have been identified under the proposed action. They are:

III. ALTERNATIVES

The proposed activity has two components. Each has separate alternatives that are discussed as follows:

Component 1: Surface Transportation of GPR Surveying Equipment

Alternative A: Use a Lightweight Vehicle to Transport the Equipment.

It is proposed that a vehicle, either light snowmobile or all-terrain vehicle (ATV), be used to tow a small, light sled with the GPR-control equipment over ice or snow surfaces. Use of a motorized technique will greatly increase our GPR surveying efficiency which will allow extension of the GPR survey over a much greater area. Coverage of a greater area will dramatically increase the scientific return during the single field season assigned to this project.

The snowmobile or ATV would be delivered to the location of the GPR survey by helicopter. The vehicle would be used exclusively on contiguous ice or snow within the survey area for towing GPR equipment. Use of the vehicle off the ice or snow would be prohibited. To collect engine drips, the vehicle would be parked either over a drip pan or fuel-absorbent materials. The exact path of the vehicle would be recorded using GPS.

Alternative B: Hand Carry All Equipment

In this alternative, the GPR-control equipment would be carried on a stretcher by field personnel.

Alternative C: No Action

In this alternative, no survey using GPR equipment would be conducted.

Component 2: Radar Antenna Movement

Alternative A: Tow Antennas Using a Motorized Vehicle

To conduct a multi-frequency GPR survey, it is proposed to tow radar antennas of various sizes smoothly along a traverse route with the antenna in contact with the ground. The antennae vary in size and weight depending on their frequency. It is proposed to employ antennas for four different frequencies. (1) The biggest, the 12 MHz dipole antenna, consists of two cables, 20 m long and weighing 50 lbs., that need to be towed about 5 m behind the control unit. (2) The 30 MHz antenna consists of two cables, 8m long, that need to be towed 5 m behind the control unit. (3) The 100 MHz antenna consists of a pair of antennas bolted together making a sleigh that is 1 m wide, 2 m long, and weighs 61 lbs. (4) The 400 MHz antenna is a 15 lb. wand with an antenna attached at the end that measures 42 x 39 cm.

Within each study region, a central transect up to a few kilometers in length will be temporarily flagged and then surveyed using GPS with sub-meter accuracy. This flagging needs to stay in place until the GPR survey is completed which we anticipate will be at most three weeks after flagging. It is proposed to run a profile along this transect for, at most, all four frequencies which translates into a maximum of four traverses along the transect. Profiles will be run backward and forward along the transect. Profiles need to be made up of straight-line segments. Assuming appropriate results from the central transect, other transects will be established within each study region and profiles run along each.

Antennas will be moved along the transect manually and by towing from a vehicle. The 400 MHz antenna will be moved manually. The three other antennas can be moved either way depending on whether the control unit is being moved by vehicle or manually.

Alternative B: Move the Antennas Manually

In this alternative, the antennae would be moved without the use of a motorized vehicle. Field personnel would drag the antennae across the surface of the land.

Alternative C: No Action

In this alternative, no radar antennae would be used.

IV. ENVIRONMENTAL EFFECTS AND MITIGATING MEASURES

Component 1: Surface Transportation of GPR Surveying Equipment

Physical effects

All-terrain vehicles (ATVs) are used on Lakes Fryxell, Hoare, and Bonney in Taylor Valley. The use of these vehicles has been described in previous environmental documents prepared by NSF including: Environmental Action Memorandum, Use of an All-Terrain Vehicle for Science Support of DPP-88-20591 (S-025) at Lake Bonney, July 16, 1991; All-Terrain Vehicle Use at New Harbor, August 16, 1994. Experience to date indicates that, with appropriate constraints and responsible use, ATVs can serve as a valuable asset for supporting research with minimal adverse effects.

The vehicle and towed sled proposed for this project would leave tracks on the lake-ice or snow surface. On both ice and snow surfaces, the marks will disappear later in the season through melting or sublimation.

The vehicle would likely release very small drops of oils, lubricants, and fuel both when operating and parked. Drip pans, liquid-absorbent pads, or other suitable spill and leak prevention equipment would be placed under the vehicle when parked, during refueling, and during minor maintenance. Substantial repairs and servicing would be performed at McMurdo Station. Fluid releases on ice and snow while the vehicle is operating would likely be minimal and likely less than the release of petroleum fluids from helicopters passing through the area. Fueling of the vehicle would be accomplished using properly fitting nozzles or funnels to minimize the potential for drips and spills.

The Principal Investigator (PI) or his designee would be required to prepare a report at the end of the season indicating: (1) where the vehicle was used, (2) when it was used, (3) the approximate distance traveled, (4) the types and quantities of petroleum products used in refueling and maintaining the vehicle, (5) the location and quantity of any significant vehicle-fluid spills. The report must be submitted to the NSF Environmental Officer within 90 days after termination of fieldwork. The report should include photographs of selected sites before and after the GPR survey.

Under NSF waste regulations (45 CFR Part 671), all unpermitted waste releases must be reported to the Director of the Office of Polar Programs within 14 days. However, it is NSF policy that all spills, regardless of quantity, be reported immediately to the Fire Station at McMurdo Station.

Air quality and noise pollution

The vehicle would be sling-loaded by a helicopter to the site of the GPR survey. This will likely require another helicopter trip to the GPR site in addition to the one bringing in the GPR gear and researchers.

Air emissions from the vehicle are similar to emissions from generators which are permitted in these regions. The emissions would constitute a negligible increase in background contaminants in the area.

There would be noise pollution during vehicle operation. This would be minimized through regular maintenance and use of a factory-installed muffler.

Health and safety concerns

There is risk in transporting, storing, and handling flammable petroleum products. The vehicle would be fueled away from sources of ignition using precautions similar to those used for fueling any vehicle in Antarctica as outlined above.

Effects on other research

Vehicle use in the GPR-survey sites mentioned above is not anticipated to have any adverse impacts on other research in these areas. Any drips of fuel, oil, and lubricants are likely to be of such small quantities that they would have negligible effects on the chemical characteristics of snow, ice, and sediment in these areas. The temporary vehicle marks on snow and ice will have no known impact.

An accident or mechanical failure could occur and result in a spill of fuel or other vehicle fluids. This could change the local chemical characteristics of the lake ice, sediments, and soils, possibly affecting data being gathered by other researchers. Materials to respond to and clean up fuel spills would be part of the required field supplies for the GPR project.

Component 2: Radar Antenna Movement

Physical effects

The physical impacts associated with antenna movement can be considered in two categories. One is the impact of antenna movement itself on the surface. The other is the impact of clearing a path for the antenna.

Concerning the first category, moving the antennas on ice or snow will leave minor tracks which will disappear as the ice and snow melt later in the year. The impact of antenna movement on sediment surfaces depends on the strength of the sediment surface and the texture of the sediments. The large majority of sediment surfaces in the Dry Valleys are armored by a desert pavement on which the antennas should not leave any significant mark. However, some sediment surfaces, such as well-sorted fluvial (river-plain) sands, are unstable and so can be marked, as they would be simply by walking on them. Hence, any damage from antenna movement would be no more severe than is currently permitted simply by allowing walking on these surfaces. Imprints on these sensitive surfaces will disappear with a few years because the sand is constantly being moved by wind, especially during winter storms.

The other category of impact relates to path-clearing for the antennas which need to be moved in straight-line segments and maintain contact with the ground. The 100 MHz antenna, at 1 m in width, is the widest antenna and so represents the worst-case scenario. Stones that project above the ground surface by more than 4-5 inches may need to be temporarily removed from the path if they are small enough to move. If they are too large for one person to pick up and move, then the antenna will be diverted around them.

As for mitigation on sediment surfaces, we will run transects over the most stable sediment surfaces available. After the GPR survey of each traverse is complete, we will restore that surface by taking the following steps. (1) Any stones that were moved off the 1-m wide antenna path will be returned to their original configuration. (2) All significant tracks will be brushed away with a broom. Additionally, we will submit a report to the NSF Environmental Officer within 90 days of fieldwork termination describing the location of all GPR traverses, the extent of disturbance due to the survey, and the condition of the surfaces after survey and remediation.

Effects on other research

Antenna movements within the GPR survey are not expected to have any effects on other research.

V. CONSULTATION WITH OTHERS

National Science Foundation/Office of Polar Programs
Dr. Scott Borg Program Manager
Antarctic Geology and Geophysics
sborg@nsf.gov
Ms. Joyce Jatko Environmental Officer
jjatko@nsf.gov

Antarctic Support Associates
Mr. Terry Johnson Environmentalist
johnsote@asa.org

University of New Hampshire:
Dr. Michael Prentice Principal Investigator for GO-063-O
mike.prentice@unh.edu

REFERENCE

Environmental Action Memorandum (Use of an All-Terrain Vehicle for Science Support of DPP-88-20591 [S-025] at Lake Bonney), July 16, 1991.

Environmental Assessment (All-Terrain Vehicle Use at New Harbor, Antarctica), August 16, 1994.


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