An integral part of the Changi sewerage treatment facility is the discharge of treated effluent into the Straits of Singapore some 5 km from the shoreline. This is achieved through twin reinforced concrete pipes laid in a dredged trench on the seabed.
Each section of the pipe is 3 m in diameter and 8 m in length and contains 7-8 t of galvanized reinforcing steel and wire. A total of 1300 pipes were manufactured on site in a slip forming operation and some 10,000 t of galvanized bar was used.
The corrosivity of seawater and the need for a 100 year life dictated the use of galvanized steel reinforcement. Because such long lengths of bar was needed to form the pipes, large amounts of coiled bar were required in addition to straight lengths.