Extract from the Mawson’s Huts Conservation Expedition 2006 Expedition Report, compiled and edited by Dr Ian Godfrey.

The 2006 Mawson’s Huts Foundation expedition boarded L’Astrolabe on the evening of 20 October 2006 and returned on the private ship Sarsen on 4 January 2007 after a highly successful expedition.

Thick pack ice slowed the journey south and stopped L’Astrolabe when she was approximately 70 kms from Cape Denison. Helicopters were then used to deploy the expedition team, supplies and equipment. These operations commenced on the evening of 29 October and were completed on 31 October. The helicopter flight in to Cape Denison showed that most of the roof of the living quarters of the Main Hut was covered with snow and ice, with the Magnetograph House completely buried. The latter did not emerge for the duration of the trip.

Despite the extensive snow coverage the team was able to achieve the major objective of the Works Plan, that being over-cladding of the living quarters roof. This was a major challenge due to the huge amount of snow that covered the building. An underlying fear was that ice and snow removal from the roof could easily be undone by subsequent blizzards. In an attempt to minimise this risk, snow blocks removed from the roof planes were used to construct a snow wall on the southern side of the Main Hut. This tactic was successful and despite many days of strong winds and wind-borne snow, very little snow was deposited in the trenches that were excavated to expose the roof planes. In total, approximately 80m³ of snow and ice were removed from the roof planes. Weather forecasts provided by the Casey and Davis meteorological teams were critical to our success, allowing us to plan our activities to coincide with appropriate weather windows. Their service was impressive, remarkably accurate and a godsend to the team.

In addition to successfully over-cladding the roof, the team also removed the original flagpole from the apex of the living quarters roof and installed a replica in its place. The replica was made to the estimated dimensions of the original. The fragile nature of the original pole and its possible loss in strong winds prompted this action. The original pole was carefully packed and returned to Australia for conservation. There was no evidence of recent snow/ice ingress other than that recorded during the 2005 expedition. This is most likely due to the extensive snow coverage that has effectively sealed the building and prevented further snow from entering through previously identified entry areas. Unfortunately, while this heavy snow coverage prevented additional snow ingress during 2006, it also prevented the team from undertaking remedial work to seal areas that are known entry points for drift snow, such as the junctions between the roof planes and walls in the workshop and Main Hut verandahs.

Snow and ice were removed from many locations in the living quarters including Webb’s bunk in the south-west corner, above Mawson’s cubicle (exposing the ‘skylight’ in his room and allowing natural light to enter this space for the first time in many years), the south-east corner (‘Hyde Park Corner’), Laseron’s bunk, the north-east corner (including what is likely to be Murphy’s bunk) and from some of the kitchen shelves. A number of interesting artefacts, including personal items and sledging supplies were exposed during these excavations.

In order to determine whether over-cladding has any impact on the interior environment of the Main Hut, the following electronic and corrosion monitoring work was undertaken:

• Stored data was downloaded from the logging system.
• Redundant and damaged temperature and relative humidity sensors were removed.
• Viable sensors were calibrated and relocated so that environmental conditions could be compared in corresponding locations in the living quarters and the workshop.
• Previously exposed corrosion monitoring cells were removed and new cells installed so that the effects of the internal environment on corrosion rates can be compared (pre and post over cladding) with that of the external environmental conditions.

Four objectives of the works program were not achieved. The extent of the snow coverage prevented access to the interface between the walls and the roof planes, thereby preventing work being undertaken to seal previously identified areas of snow ingress into the building and to over-clad the south wall of the Main Hut. No attempt was made to excavate ice to floor level from the entrances/doors to the workshop. As all areas of snow ingress had not been sealed, this action was considered premature. A fourth objective was also not realised, that being to make an outgoing call from the satellite phone connected to the environmental monitoring system. This was attempted in order to allow the system to be recognised by the Iridium network and therefore allow external access to the environmental data as it was being collected. The environmental monitoring system will continue to accumulate data but this will not be available until it is downloaded during the next expedition to the site.

Additional work undertaken included:

• The installation of vibration sensors to monitor any movement in structural timbers over the coming year.
• Sampling of mould outbreaks noted on artefacts (food, paper objects) and timber panels.
• Relocation of the timber stack from in front of the Granholm Hut to a site adjacent to the Sorensen Hut.
• Replacement of the single barrel lock on the workshop door with two locks (top and bottom) to reduce distortion and assist in reducing snow ingress.
• Improving the amenity of the Sorensen Hut by extending the decking and installing a set of stairs.

The team also hosted visits to the site by expeditioners from the Spirit of Enderby and the Sarsen. Tours through the hut were given as was shelter in the Sorensen and Granholm Huts when blizzard-like conditions arose during a visit by the Spirit of Enderby expeditioners.

This report recommends that future work at the site be directed towards:

• Monitoring and remediation work in areas of snow ingress with particular attention to wall/ceiling junctions.
• Over-cladding of the south wall of the Main Hut in the longer term.
• Removal of more snow and ice to reveal interior spaces and artefacts.
• Continuation of the monitoring program.
• The development of an interpretation plan to guide conservation processes for the interior of the Main Hut (artefacts and fittings such as shelves etc) and to take into account the possible eventuality of fuller exposure of the floor (and associated artefacts) in both the workshop and the living quarters as the hut is better sealed and ablation continues in the future.
• Prioritisation of artefacts for conservation treatment and commencement of an active program designed to stabilise corroding and deteriorating artefacts.
• Documentation of the transit hut, absolute magnetic hut and magnetograph house.

Improvements in the visual protection zone, including painting of the Granholm Hut to reduce the effects of its presence in this zone, while major works continue at the Main Hut and while it is still considered an important on-site refuge. Note that this recommendation is at odds with the recently issued draft management plan and will be the subject of further discussion. Building and packing materials should be removed from this zone when they emerge from the snow and ice.