Designed as a typical microtunnel project with several short, straight drives, the SARI Mainline offered JWF the perfect opportunity to offer an innovative value engineering proposal to eliminate shafts and combine multiple drives on the project. This saved the Orange County Sanitation District over $1 million and offered a 20% reduction in the tunneling schedule.
The microtunneling consisted of approximately 4,000 feet of 101.5-inch OD microtunnel done in four drives with installation of 2,900 feet of 84-inch ID reinforced concrete pipe and 1,100 feet of 99.5-inch ID steel casing at approximately 36 feet below the ground surface.
This project was the first in the United States to have two curved drives. It also was the first use of an innovative hydraulic gasketed joint in North America. The radius of the compound curve was approximately 15,500 feet and the standard curve was approximately 5,500 feet.