Box HER9 Port Arthur Penitentiary—extreme weather impact on historic sites

Climate change is already posing risks for Australia’s World Heritage properties, including historic sites. The Port Arthur Historic Site is one of the 11 historic places that together form the Australian Convict Sites World Heritage Property, which was inscribed on the World Heritage List in 2010.

At Port Arthur, high tides and storm surges threaten historic assets. In 2011, a major storm occurred concurrently with a high tide, flooding the Port Arthur Penitentiary. The impact of debris damaged the building, and salt water soaked into the fragile brick and sandstone walls.

Originally constructed as a flour mill and granary, the penitentiary was converted in 1857 to house more than 480 convicts in dormitory accommodation and separate apartments. At the time of construction, it was the largest building in Tasmania, and remains a potent symbol of Australia’s penal origins.

The 2011 storm triggered a reassessment of the structural integrity of the penitentiary and confirmed the requirement for a major stabilisation project. Commencing in early 2014, the project was funded by the Tasmanian and Australian governments, and the Port Arthur Historic Site Management Authority, using revenue raised from heritage tourism.

This substantial conservation project included the installation of reinforced concrete ground beams supporting 14 huge steel columns; around 5 kilometres of stainless steel reinforcing rod; 91 high-tensile stainless steel grouted structural anchors, precision drilled vertically down through the walls; and stainless steel bracing plates, which are concealed beneath the sandstone cornice.

The project addresses the potential impact of future storm surges and will ensure the long-term conservation of the structure. It also provides the opportunity to interpret the building in new and exciting ways that will enhance the visitor experience.

The penitentiary project illustrates the need for heritage managers to adapt to new risks, and to monitor and manage the impacts of those risks. It is important that skilled staff and systems are in place to protect the fabric and values of the site by minimising damage when extreme events occur.

Source: Port Arthur Historic Site Management Authority

Severe weather and high tides at Port Arthur, 2011

Severe weather and high tides at Port Arthur, 2011

Severe weather and high tides at Port Arthur, Tasmania, 2011

Mackay R (2016). Heritage: Box HER9 Port Arthur Penitentiary—extreme weather impact on historic sites. In: Australia state of the environment 2016, Australian Government Department of the Environment and Energy, Canberra, https://soe.environment.gov.au/case-study/heritage/box-her9-port-arthur-penitentiary-extreme-weather-impact-historic-sites, DOI 10.4226/94/58b658bbe13a0