When collecting samples during site characterization, how deep should each sample be collected?

The appropriate depth for collecting samples during site characterization is a minimum of 6 inches. This depth is significant because it typically allows for an adequate representation of the subsurface materials and conditions that may be impacted by potential contamination. By collecting samples at this depth, you can ensure that you are reaching a zone where contaminants, if present, would likely accumulate due to gravitational settling, surface runoff, or other environmental factors.

Sampling at depths shallower than 6 inches may not capture the full extent of contamination as surface conditions can differ significantly from those found deeper in the soil. Additionally, some pollutants can migrate through the soil over time, potentially allowing for a more accurate assessment of the contaminated zone when samples are taken from a lower depth. This makes the 6-inch benchmark a practical standard in the field of environmental site assessments.