What is the minimum separation for ducts crossing utilities when crossing passes through tamped dirt?

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Multiple Choice

What is the minimum separation for ducts crossing utilities when crossing passes through tamped dirt?

When underground ducts cross other utilities through tamped dirt, maintaining a clear vertical separation protects both systems during backfill, future digging, and routine maintenance. A minimum of 12 inches provides enough room to accommodate backfill settlement, allows access for inspection or repair, and reduces the risk of contact, abrasion, or crushing if the surrounding soil settles or if equipment comes near the trench. Smaller gaps—6, 3, or 1 inch—do not offer sufficient clearance and increase the chances of damage or interference, which is why 12 inches is the preferred minimum.

When underground ducts cross other utilities through tamped dirt, maintaining a clear vertical separation protects both systems during backfill, future digging, and routine maintenance. A minimum of 12 inches provides enough room to accommodate backfill settlement, allows access for inspection or repair, and reduces the risk of contact, abrasion, or crushing if the surrounding soil settles or if equipment comes near the trench. Smaller gaps—6, 3, or 1 inch—do not offer sufficient clearance and increase the chances of damage or interference, which is why 12 inches is the preferred minimum.

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