Coastal waters are increasingly polluted by the polluted water which is discharged from lands. Due to such increased polluted water discharge, the degree of coastal water pollution has been considerably increased. For solving this pollution problem in coastal area, polluted water is firstly purified by a proper process and then discharged into far coastal water through a ocean outfall pipeline. A outfall pipeline system consists of main pipe, riser and diffuser. Because an ocean outfall riser is week to ocean environmental loads, it must be designed in safe and economic point of view. Therefore technical examination is needed in the preliminary design stage.
In this study, various hydraulic model experiments are accomplished for the examination of ocean outfall riser safety and some numerical analyses are carried out for its fatigue failure. A case study is carried out for the ocean outfall riser which is installed near Gadukdo in Busan.