The first major use of hybrid ground treatment, Jet Mechanical Mixing (JMM), in Singapore, was in the construction of the new Nicoll Highway Station (NCH) for the Circle Line Project (CCLP). This system played a major role in the success of the project. The retaining wall design was a 1.5m thick diaphragm wall to provide support of the ground during the station construction and also as the permanent walls of the station. The proposed construction scheme is that of top-down with the use of a 7m thick JMM below the base slab level, which comprises a large diameter deep soil mixing method comprising a central core combined with a jet-grouted outer circumference to form a large diameter of improved soil mass. This paper aims to demonstrate the effectiveness of the excavation support system and benefits of JMM in reducing wall movement of deep excavation in soft ground with 35m thick of Marine Clay.