Which one of the following statements about retaining wall drainage is FALSE?

The statement regarding the use of soils that drain well, such as clay, behind retaining walls is false because clay is actually a poor choice for this application. Clay has very low permeability, meaning it retains water rather than allowing it to drain. This can lead to an accumulation of water behind the retaining wall, increasing hydrostatic pressure and potentially compromising the structural integrity of the wall. In contrast, well-draining materials, such as gravel or sandy soils, are more suitable as they allow water to flow away from the wall, reducing pressure and the risk of failure. Proper drainage is crucial in retaining wall design, and using clay behind the wall counteracts the effectiveness of necessary drainage systems, such as weeping tiles or drainage holes, which are designed to alleviate pressure buildup.