Soil replacement should be how deep?

Soil replacement should be how deep?

• A. 3 inches
• B. 6 inches
• C. 9 inches
• D. 12 inches

Answer: (B)

The key idea is that lead in soil poses exposure mainly from the top layer where children play and dust settles. Replacing soil to a depth of about six inches removes the most contaminated portion and provides a clean surface for safe play. A shallower replacement, like three inches, may leave contaminated soil beneath and allow recontamination. Deeper replacement, such as nine or twelve inches, is usually unnecessary for typical residential hazards and adds extra cost and disturbance without extra safety benefit. Six inches balances effective removal of the contaminated layer with practicality and cost.

The key idea is that lead in soil poses exposure mainly from the top layer where children play and dust settles. Replacing soil to a depth of about six inches removes the most contaminated portion and provides a clean surface for safe play. A shallower replacement, like three inches, may leave contaminated soil beneath and allow recontamination. Deeper replacement, such as nine or twelve inches, is usually unnecessary for typical residential hazards and adds extra cost and disturbance without extra safety benefit. Six inches balances effective removal of the contaminated layer with practicality and cost.