Coastal and Floodplain Construction Inspector's Practice Exam

What is the requirement for foundations constructed in erodible soils?

1. They can rest on the surface soil.

2. They must be founded on piles.

3. They should use heavy concrete blocks.

4. They must be anchored to bedrock.

The correct answer is: They must be founded on piles.

Foundations constructed in erodible soils must be founded on piles to ensure stability and prevent settlement or failure caused by soil erosion. Piles are deep foundation elements that extend through the unstable or erodible soil and reach a more stable layer beneath, such as denser soil or bedrock. This method helps transfer the structural loads to a more competent layer, minimizing the risk associated with soil erosion, which can undermine the foundation's integrity. Using piles is particularly important in coastal and floodplain areas, where soil can be subject to various erosion processes due to water movement and changing environmental conditions. Other methods, such as resting solely on surface soil or using heavy concrete blocks without proper anchoring, may not provide sufficient support and can lead to instability. Anchoring to bedrock is also a sound approach but may not always be practical depending on the depth of the bedrock and the geotechnical conditions prevalent at the site. Therefore, relying on piles as a foundation system provides a reliable and effective means of mitigating risks posed by erodible soils.