Abstract
Drainage of the depressed interstate 10 inner-loop extension in phoenix, arizona, required the construction of a conveyance system composed of pressure tunnels, 14 to 21 ft in diameter, beneath the city. the geologic and engineering parameters specific to this project and the method of construction used in stream-transported alluvialsoils are described. minimization of surface settlement and concernfor lowering of the groundwater table, which is almost completely controlled by the nearby salt river, influenced construction methods and contractual provisions. this paper appeared in transportation research record no. 1150, tunneling. for covering abstract see irrd no818446.