BHP Billiton has released the final supplementary environmental impact statement (SEIS) for the expansion of its Olympic Dam project in South Australia.

The firm submitted the SEIS for review by the Australian, South Australian and Northern Territory governments.

The governments have performed a series of adequacy checks on the SEIS and granted the firm permission to release the document publicly.

The firm is awaiting the final government approvals for the proposed expansion of the project.

BHP Billiton uranium customer sector group president Dean Dalla Valle said the Olympic Dam project, which has uranium deposits along with copper and gold resources, will inject billions of dollars into the South Australian economy.