Information released to the Otago Daily Times under the Official Information Act reveals 122 new beds will be added to existing cells at Milburn, while 28 twin cells will be used permanently to house extra prisoners.
There is still no word on whether shipping containers or other forms of prisoner accommodation are being considered for the corrections facility site but the department said the new beds will ready for use by February next year.
While the department has confirmed some details of the double-bunking project, it continues to withhold details of cost, claiming to release that information "would be likely to unreasonably prejudice the commercial position of the department and withholding is necessary to enable the department to carry out commercial activities without prejudice or disadvantage."
The project's contract is still out for tender although that process is expected to be finished by July 27.
The department did say the Government had approved $145.8 million for double-bunking work at five prisons around the country.
The work at the Otago facility will raise the prison's capacity from 335 to 485.
The Government has introduced double-bunking around the country to cope with predicted rising prisoner numbers over the coming months.
