Today, two massive screws of S31600 stainless steel have been installed and eight more are under construction for the vast Hyperion Wastewater Treatment Plant in Los Angeles, one of the largest such facilities in the world. Each of the 10 screws is 3.8 metres in diameter and 15.2 metres long, and weighs 36.4 tonnes. In total, 364 tonnes of stainless steel, containing about 12% nickel, will be used to replace the existing epoxy-coated steel screws, which have corroded. The oceanside Hyperion plant has been operating since 1951, but in the early 1990s a design change forced the installation of an intermediate pumping station (IPS) to raise the wastewater almost five metres so that it flows by gravity through the rest of the plant. The 10 Archimedes screws were the pumps of choice in the IPS. The Archimedes screws are being constructed by Spaans Babcock, The Netherlands. Other stainless applications in the plant include piping, digesters and other components.
