1. Key words: natural soil, clayey sand, Singapore Old Alluvium, heterogeneity, granular void ratio.

2. Characterization of the Old Alluvium (OA) Formation in Singapore is difficult due to its natural heterogeneity.

3. The centre of the town, between Labbés, Genin, and Texier, is located on old alluvium from the Quaternary period.

4. On the basis of their physical properties and their engineering characteristics, the Miocene, Pliocene and Quaternary deposits were divided into six units: unconsolidated man-made fill, unconsolidated surficial recent alluvium, unconsolidated surficial young alluvium, consolidated old alluvium, highly weathered soft rock units and slightly weathered relatively resistant rock units.