This paper provides a case history of Diaphragm Wall construction at the Southern Desalination plant. GFWA were contracted on a construct only basis by the Southern Sea Water Alliance (SSWA), to install the Diaphragm Walls forming the Intake Pump Station. Construction was carried out between September 2009 and April 2010. 38 No. 1.0m thick heavily reinforced diaphragm wall panels were installed to depths of 25.0m in variable ground conditions, totalling 6,250 m2. 15 No. 2.8 x 1.0m Barrettes were also constructed to facilitate support of ancillary structures.