Trancas Road Repair Project - RDS25-35

Trancas Street was paved in 2001 with a 0.2-ft overlay and in 2012 with a 0.15-ft overlay. Although asphalt thickness was not considered for its impact to the floodplain in previous projects, the County proposes a 2.5-inch mill and fill and various 3-inch digouts, to correct pavement deficiencies, provide for a 15-20 year design life, and prevent impacts the floodplain elevation. The southern branch of the "Y" intersection of Trancas Street with Monticello Road and SR-121, will undergo a 1.5-inch mill and fill as the existing asphalt section over Bridge No. 21C0051, crossing Milliken Creek, is approximately 1.5-inches. Trancas Street will be restriped to match existing striping, but will include an extended left turn pocket (an additional 100-ft) for eastbound traffic making a left onto Silverado Trail. The extension to the left turn lane pocket will not modify the existing footprint of the road and all work will occur within the existing travel lanes and shoulder areas. The project will incorporate best management practices and no removal of vegetation (outside of typical roadway clearing and grubbing practices) is proposed as part of this project. As Trancas Street is within the Napa River floodway, the upcoming paving project will maintain pre-project elevations to prevent a rise in the floodway elevation. As such, t.he County has filed a Floodplain Management Permit Application with The Planning, Building, and Environmental Services Department. Due to floodplain restrictions that limit the pavement thickness on Trancas Street, the County will provide a mill and fill treatment to the asphalt.