Development work on the Dunedin Town Hall will resume today, following confirmation the site is safe.
Offensive-smelling material discovered in the town hall basement by contractors on March 7 has been laboratory tested and is not deemed hazardous to health.
Gas levels on site are also well below Department of Labour exposure standards for workplaces.
The asphalt-like material is a by-product of the process in which coal was used to make gas, and was laid in the basement under a concrete pad to prevent moisture damage.
Town hall redevelopment project manager David Booth, of OCTA Associates Ltd, said the substance covered an area measuring about 10m by 5m and was about 400mm thick.
It will be removed by contractors next week during the evening, to ensure the strong mothball-like odour affects as few people as possible.
The substance will then be taken to a landfill, specially treated and disposed of in an area designated for contaminated material, under the management of Delta.
Mr Booth said he was pleased with the outcome and estimated the material discovery and removal would have only a minor effect on the project as a whole.
To ensure all workers were happy about returning to the town hall, Mr Booth and others involved in dealing with the material held a site briefing yesterday afternoon.
The substance has not been discovered in other parts of the construction site.
While the town hall was closed, contractors were paid and worked on another Dunedin City Council site as well as a community volunteer project.
Redevelopment of the town hall is being undertaken as part of a wider $45.8 million Dunedin Centre and town hall upgrade.
Work began last November and is expected to be completed early next year.
