The explosives and chemical maker has made a submission to the NSW Department of Planning.

An environmental assessment of its Kooragang proposal will go on public exhibition from Tuesday as part of the approval process.

Orica estimates that the proposed expansion would increase manufacturing capacity from 430 kilotonnes a year to 750 kilotonnes a year.

About 250 building jobs, more than 20 permanent roles and 50 contract positions in maintenance, transport and support services would be added to the Kooragang Island plant's 200-strong workforce.

The company supplies explosives to mining, quarrying and construction industries and said the expansion would help it cater to growing demand.

"Orica has been an essential supplier to the Hunter mining and construction industries for many years and this proposed plant expansion is another significant commitment to the local economy," Kooragang Island expansion project manager Carey Gent said.

"The project is needed to support the planned increases in mining and construction activity in eastern Australia and the Hunter Valley, which will see continuing growth in demand for Orica's products."

The first stage of the project is scheduled for completion in 2011.

In association with the proposed expansion, Orica will give Newcastle City Council $272,000 for upgrading Corroba Oval in neighbouring residential suburb Stockton.

This is in lieu of developer levies that might have been payable.