THE Territory's nuclear waste facility could cost about $30 million to build, it was learned yesterday.

The estimate comes from the experience of similar depositories overseas.

A South Australian company, Parsons Brinckerhoff, has won the tender to assess the three sites earmarked for the facility.

Managing director David Cruikshanks-Boyd declined to discuss the contract.

``It's a matter of client confidentiality,'' he said yesterday.

But the Northern Territory News understands work will start within weeks.

The environmental engineering company carried out the study of the original site chosen at Woomera.

The plan was dropped after the South Australian Government launched a Federal Court challenge.

The three Defence-owned Territory sites are:

FISHERS Ridge, 40km east of the RAAF Base Tindal near Katherine;

HART'S Range, 200km northeast of Alice Springs;

MOUNT Everard, 42km northwest of Alice.

Parsons Brinckerhoff will carry out geological, hydro-geological, climatic and flora and fauna studies at each site.

The company will give the Federal Government assessments by the end of this year but will not make a recommendation about which site should be chosen.

The Federal Government is reported to have two designs for the facility.

One allows for three basketball hall-size storage sheds _ two for low-level waste and a third for intermediate waste _ inside a fortified enclosure with only one entrance.

There would also be an unloading bay and a security block.

The other design would be used if the site was suitable for underground storage of low-level waste.

It would have a single intermediate-level waste storage shed and a low-level waste repository 5m underground.

Work on building the facility will begin in 2010 and be finished within eight months.