Which of the following is true about contamination above 500 ppm?

When it comes to contamination levels above 500 parts per million (ppm), it is crucial to consider how to manage and address the contamination effectively. The correct answer is that estimates may be used to delineate contamination. This means that when dealing with significant contamination, detailed and extensive assessments may be impractical or costly, so estimates can provide a framework for understanding the scope and extent of the contaminated area.

Using estimates allows for a more efficient approach to determining the boundaries and conditions of the contamination without requiring complete removal of all soil or immediate action, which can be cumbersome. It acknowledges that not every situation will require exhaustive data collection, especially in urgent situations where safety and environmental integrity must be balanced.

This option reflects a practical approach to environmental management and remediation by leveraging estimative techniques to guide the decision-making process.