THE federal Environment Department faced questions over the approval of the Gladstone Ports Corporation's Western Basin dredging project in 2010 during Senate estimates on Monday.
Officials from the department took on notice a series of questions surrounding the approval and a warning of potential failures in the environmental assessment of the project dating to 2009.
The estimates hearing follows recent revelations the Great Barrier Reef Marine Park Authority warned the department that the dredging should trigger a strategic assessment of all developments in Gladstone Harbour.
APN revealed earlier this month the authority warned there could be a failure of environmental assessments of the project if such an assessment was not completed.
Queensland Greens senator Larissa Waters asked officials several questions about what checks it undertook before recommending the project be approved.
She also asked the department what action it took on the GBRMPA warnings, first sent in 2009, more than a year before the project was approved.
But the department's first assistant secretary of the environment assessment and compliance division, Dean Knudson, said he was unable to answer the questions during estimates on Monday.
He asked that answers could instead be provided "on notice", to allow the department to respond in writing at a later date.
The department has previously declined to comment on the warnings, referring such requests to be pursued through the Freedom of Information Act.
Update your news preferences and get the latest news delivered to your inbox.