Which Hydrologic Soil Group has very low infiltration rates when thoroughly wetted?

The correct answer is that Hydrologic Soil Group D is characterized by very low infiltration rates when thoroughly wetted. This group typically includes soils with a high clay content or soils that are highly compacted, which restrict water movement through the soil profile. As a result, these soils tend to have poor drainage abilities and can lead to increased runoff, which is a critical factor in erosion and sediment control practices.

Understanding the characteristics of Hydrologic Soil Groups is essential for assessing the potential for erosion and managing stormwater effectively. Group D soils may require specific management practices to mitigate runoff and reduce the risk of erosion, especially in construction and land development projects.