The taxpayer-funded Darwin ship lift project’s costs have jumped by more than $100 million after the Fyles Government announced the Clough-BMD joint venture has been selected as the contractor for the major project that has never seen an economic assessment publicly produced and that will be operated privately by Paspaley Group.

Chief Minister Natasha Fyles announced the contractor on Saturday and also revealed then that the NT Government has budgeted $515 million for the ship lift – $115 million more than previously reported.

The funding will see Territory taxpayers shell out more than $200 million, with the other $300 million in the form of a concessional loan from the federal Northern Australian Infrastructure Facility (NAIF).

Paspaley is not contributing any money to the project.

The government said in a statement that the $515 million will cover construction costs, “as well as other ancillary works being undertaken by the Northern Territory Government”.

In December, the government announced that two contractors had been shortlisted for the project, Territoria Civil and the Clough-BMD Joint Venture. The price at that time was $400 million.

“The selection of Clough-BMD Joint Venture follows a three-stage procurement process which spanned two years,” Ms Fyles said in a statement.

“The ship lift at East Arm will bring millions into the NT economy every year. It will employ 250 people at the peak of construction, and will generate and maintain hundreds of local jobs in the maritime support sector. The ship lift is also key enabling infrastructure for the future marine industry park.”

Chief Minister Natasha Fyles, NT Infrastructure Commissioner Louise McCormack and Eva Lawler.

The government did not say how they determined those figures.

The Auditor General previously found in 2018 that the $100 million the government had pledged for the ship lift at that time was not based on any economic modelling and that the government did not complete a cost-benefit analysis.

An early pre-feasibility report considering the direct economic benefits of what was then proposed as a larger “marine maintenance precinct” found it would return just 65 cents for every dollar spent, but the rest of the project has since been scrapped and will now only be a ship lift facility, which the government has not been able to provide any modelling that shows it will be feasible.

The government said on Saturday that the ship lift would be capable of servicing large vessels of up to 5000 tonnes and will “be used for multiple industries including offshore petroleum, fishing, pearling and Defence and Border Force”.

Neither the ADF nor Border Force have committed to using the facility.

Ms Fyles said the announcement of the Clough-BMD Joint Venture as the winning contractor was “symbolic and historic”.

“As a key piece of enabling infrastructure, the ship lift will establish Darwin as a key maritime maintenance hub and create the opportunity to grow a thriving marine service and supply sector in Darwin to create jobs and grow businesses and is key to establishing a marine services precinct at East Arm,” she said.

The government expects the project to be operational by the end of 2024.