Clinton CSO Underground Tunnel

Overview

We proposed an alternate value engineering scheme for the construction of the Clinton combined sewer overflow (CSO) storage facility in Onondaga County, New York. The facility retains excess combined sewage during storm events, allowing the flow to be treated during lower flow periods while avoiding overflow discharges.

Highlights

• In the bid documents, the original storage facility was designed as three parallel soft ground tunnel borings between two open excavated reinforcedconcrete chambers.
• The value engineering that we developed consisted of three rectangular culverts installed as cut-and-cover tunnels within the same footprint as the tunnels. The cut-andcover culverts provided more storage capacity than the three circular tunnels, reduced costs and shortened the construction schedule.
• The permanent storage tank is 800 feet long between the chambers, having a width of 53 feet and a height of 24 feet. The chamber structures have a depth of 50 feet.
• We served as the engineer of record, redesigning the entire storage facility, including the three culverts and chambers at each end. The design incorporated the innovative use of a cement bentonite wall as temporary support of excavation, using wide flange members as vertical reinforcement with two levels of cross lot bracing.
• In order to reduce the construction schedule and improve the construction quality of three parallel tanks, the SOE system is configured to enable a slipform construction for the tank, which is 23 feet tall. The three tanks and two chambers were designed to meet the requirements of ACI350.