Hawaii’s Department of Health will use a $2.1 million federal grant to run a three-year program expected to serve at least 120 people who are considered chronically homeless.

The U.S. Substance Abuse and Mental Health Services Administration grant will provide housing and support services to those who are homeless while suffering from substance abuse and mental health disorders on Oahu.

The state said Wednesday the program is scheduled to begin next year. It will be based on a national model that provides comprehensive housing and treatment services, along with other services such as vocational and mental health support.

According to the state, an estimated 45 out of every 100,000 residents in Hawaii are homeless.