What is the minimum width of a gravel diaphragm trench?

What is the minimum width of a gravel diaphragm trench?

• A. 1 foot
• B. 3 feet
• C. 4 feet
• D. 2 feet

Answer: (D)

Gravel diaphragm trenches need enough width to fit the gravel bed, the pipe, and the surrounding filter fabric with proper clearance so water can flow through without crowding the sides. This cross-section also has to allow room for stable backfill and future maintenance access. Two feet is the minimum width that provides that necessary space. If the trench were only one foot wide, there wouldn’t be enough room to place the pipe and the gravel properly, and the fabric and stone would be cramped, increasing the risk of clogging and improper distribution. Wider trenches (three or four feet) can be used for specific site conditions, but they’re not required to meet the minimum standard.

Gravel diaphragm trenches need enough width to fit the gravel bed, the pipe, and the surrounding filter fabric with proper clearance so water can flow through without crowding the sides. This cross-section also has to allow room for stable backfill and future maintenance access. Two feet is the minimum width that provides that necessary space. If the trench were only one foot wide, there wouldn’t be enough room to place the pipe and the gravel properly, and the fabric and stone would be cramped, increasing the risk of clogging and improper distribution. Wider trenches (three or four feet) can be used for specific site conditions, but they’re not required to meet the minimum standard.