What types of samples are analyzed for diesel and BTEX according to regulations?

The correct response indicates that analyzing soil/water interface samples is crucial for detecting contaminants like diesel and BTEX. This type of sampling is essential because the interface can reveal the presence of pollutants that might be migrating from the soil into the groundwater or vice versa.

The soil/water interface is where the two mediums meet, often serving as a zone where contaminants accumulate or become more concentrated. By analyzing samples from this interface, one can obtain valuable information about how pollutants are interacting between the soil and water, which is vital for assessing environmental impact and guiding remediation efforts.

Sampling only water or only soil may not provide a complete picture of contamination levels, leading to potential underestimation of the environmental risks associated with diesel and BTEX. Any soil and water samples, while broad, do not specifically address the critical layer where contamination is most likely to occur. Thus, focusing on the soil/water interface ensures more accurate and pertinent data for regulatory compliance and environmental protection.