A controversial plan to dump dredge spoil onshore will not damage nationally significant wetland, Queensland’s deputy premier, Jeff Seeney, says.

Three million cubic metres of dredged material linked to the expansion of the Abbot Point coal terminal near Bowen in north Queensland was destined to be dumped in waters off the Great Barrier Reef.

But a backlash against the plan, which had gained federal approval, prompted the state government to endorse onshore dumping instead.

Seeney says the strategy has been submitted for federal government approval.

“We are confident that, if approved by the commonwealth, we can have state-owned land ready to receive dredge material for when licensed dredging activity begins next March,” he said in a statement.

But the North Queensland Bulk Ports Corporation project could be delayed by green groups, which have launched federal court proceedings challenging the environmental approval validity.

The Mackay Conservation Group secured more time in late September to put its case to the court, initially due at the end of October, saying there was uncertainty around the onshore dumping plan.

The group remains opposed to dredging, saying onshore dumping will damage a nationally significant wetland that is home to several threatened species.

Documents submitted to the commonwealth on Friday state that if approvals are not granted “in a timely manner”, the spoil could be dumped at sea.

“Project proponents that need to dredge at Abbot Point will have no option but to dispose [of] material in the [Great Barrier Reef] marine park in accordance with existing approvals,” the document said.

Seeney said the wetlands would be preserved under the onshore dumping strategy.

“We are inviting the local community and environmentalists to work with us to restore freshwater flows to degraded areas of the wetland, expand its area and consider access points for the general public to boost tourism activity in the area,” he said.