The Sonoma County Board of Supervisors on Tuesday approved a $22.7 million contract for extension of the two runways at Charles M. Schulz-Sonoma County Airport.

The work was awarded to O.C. Jones and Sons, a Berkeley-based contractor that was the low bidder among six firms competing for the contract.

Construction work is tentatively set to begin in mid-August and wrap up by October 2014.

The runway extensions and other upgrades called for in the contract are intended to improve safety and attract more commercial flights to the airport.

The overall project cost, including engineering and habitat mitigation is $53.8 million. Federal grants will cover 90 percent, while the county is funding the remainder through fees on airline tickets.

The main runway is to be lengthened by 885 feet to 6,000 feet. Two hundred feet will be added to the second runway.

O.C. Jones was the lead contractor on the $82 million project that added a third lane to both directions of Highway 101 between Santa Rosa and Windsor.