Mate do you really think the State Government of WA would...

Mate do you really think the State Government of WA would provide a commercial legally binding lease to a company without checking first if they had the power to do so? That would be shockingly negligent.

From the Environmental Assessment:

"The Proposal is located on land and waters set aside by the State under Section 19 of the Mining Act 1978 (WA) (Mining Act), a section that excludes the specified land from the Mining Act with the stated purpose of S19/315, to “reserve the land for the development of a multi‐user port”. In addition to this land, a corridor of land connecting to the North West Coastal Highway will be resumed by the State for the purpose of public access to CPE. The land will be vested in the DPA under the Port Authorities Act 1999 (WA) (PA Act). "

You are free to check those Acts out.