How deep should soil be removed after a spill on loose clay or clay-loam soil?

When dealing with spills on loose clay or clay-loam soils, removing soil to a depth of 5 inches is appropriate. This depth is considered a standard practice to effectively mitigate the potential contamination from the spill.

Clay and clay-loam soils have specific properties that can influence the behavior of spilled substances, particularly their ability to retain moisture and chemicals. Due to these properties, contaminants can be absorbed into the soil, further necessitating careful removal beyond just the immediate surface.

At 5 inches, the goal is to ensure that a sufficient amount of contaminated material is removed without digging too deep, which could disturb the soil structure or lead to unnecessary excavation costs. This depth strikes a balance between effectively addressing the contamination while minimizing disruption to the soil profile, which is vital for maintaining soil health and preventing erosion or other secondary environmental issues.

In contrast, depths that are either too shallow may leave behind residual contaminants, while depths greater than 5 inches could result in unnecessary excavation and challenges in remediation. Therefore, the recommended removal depth of 5 inches is a calculated approach to ensure effective remediation in these types of soil conditions.