The new Youth Justice facility, under construction at Cherry Creek passed a major milestone this month, with more than 500,000 labour hours worked on the project since construction commenced.

The $419 million project is providing a major economic boost to the Werribee area during construction and will support more than 250 ongoing jobs once the facility is fully operational.

There are now more than 400 workers on the construction site each day, with groundworks on track to be completed in May 2021 and multiple buildings now well under construction.

The foundations have now been laid for 140 accommodation beds, an intensive intervention unit, specialised health care unit, intensive alcohol and drug treatment unit, dedicated mental health beds, education, vocational skills, recreation and spiritual facilities.

At least 90 per cent of materials being used in construction are local, with over 10 per cent of work hours going to apprentices and trainees.

The 250 jobs created once the facility opens will include youth justice custodial officers, psychologists, teachers, health workers and administrative and maintenance staff.

The specialised facility has been designed with a focus on staff safety and reducing reoffending among young people aged 15 to 18 years with complex and challenging backgrounds.

The design allows the facility to flexibly accommodate young males on long-term remand, undergoing sentence, or both, within distinct communities.

Construction is being managed by John Holland, overseen by the Community Safety Building Authority, which delivers infrastructure on behalf of the Department of Justice and Community Safety.