Prestressed Pipe for Power Site in New Zealand

The design and construction of the offshore Circulating Water System for the 240 mw Marsden Power Station utilized unusual design and construction methods which were made possible by employing unique transportation techniques. Eight-foot sections of 78-in. diam precast concrete pipe were epoxy glued and prestressed into 120-ft strings and units of four strings were Joined to form rafts. The rafts were launched into the ocean, floated about 90 miles to the site and laid in a trench for eventual cover to six ft below the ocean floor by employing buoyancy principles. The station consists of two 120-MW oilfired units. The condenser cooling water is obtained from the ocean through a prestressed concrete pipe conduit system with the inlet and outlet located 2800 ft and 2000 ft offshore, respectively.