Sonoma County supervisors Tuesday approved a $9 million contract for a Novato-based construction firm to begin work on a tunnel, bridge and elevator tower through which inmates will be escorted between the jail and a long-awaited new courthouse in Santa Rosa after it’s built and opened in four years.

Workers will break ground on the tunnel portion of the project next month in what will be the first tangible sign Sonoma County may get a new Hall of Justice, a stalled project restarted earlier this year when Gov. Jerry Brown secured state funding to replace the state’s most outdated and seismically dangerous courthouses.

Construction on Sonoma County’s $175 million six- story courthouse is scheduled to begin sometime next year on a 6.8-acre site next to the current 52-year-old facility. Sonoma County Superior Court’s presiding judge, Gary Nadler, said he expects the building to open its doors by July or August 2022.

“We are in a good funding situation now,” Nadler said. “It’s backed by state resources, and we are full speed ahead here at the courts working on this courthouse.”

While the cost of building a courthouse will be paid by the state, Sonoma County is on the hook for building a way for inmates to securely travel between the jail and new courthouse. Supervisors David Rabbitt, Susan Gorin and Lynda Hopkins expressed concerns about the significant cost to the county at Tuesday’s board meeting before the supervisors voted unanimously for staff to move ahead with the construction contract.

The state “should be made aware of the additional costs on the local level to accommodate what they will build,” Rabbitt said.

“It’s unfortunate the cost is so substantial but this is a critical need and I understand,” Hopkins said.

The work will be done by Novato-based Thompson Builders Corp. at a cost not to exceed $9,085,658, county general services director Caroline Judy said. The connection project was designed to handle daily traffic of between 150 and 180 inmates who are escorted between the main jail to the court. Inmates will walk across a bridge from the jail’s third floor to an elevator tower. The elevator tower will bring inmates below ground to a tunnel that connects to a lower level of the new courthouse, according to the design plans.

Courthouse construction was funded by legislation in 2008 increasing fees and fines supporting $5 billion in bonds. That year, a state report recommended replacing Sonoma County’s Hall of Justice, calling the facility, which opened in 1966, overcrowded, unsafe and unable to be fixed.

Nadler said the new Hall of Justice — just east of the existing courthouse on Administration Drive — will be designed with seismic and environmental standards using natural light and top efficiency standards.

The project architects are a Los Angeles-based team from Richard Meier & Partners, the firm that designed the Getty Center in Los Angeles, the Barcelona Museum of Contemporary Art and a federal courthouse in San Diego. The building plans include 15 criminal courtrooms and will include improved jury assembly rooms, in-custody holding areas and allow criminal, traffic, juvenile dependency, probate and family court mediation and other proceedings to be conducted at one location.