What is the maximum depth at which a warning ribbon is required to be installed when a service lateral is directly buried?

When service laterals are directly buried, there are regulations regarding the installation of warning ribbons to alert individuals of the underground lines. The requirement for the maximum depth at which a warning ribbon must be installed is set to ensure safety, as it is crucial for preventing accidental damage to the buried utilities during excavation or landscaping activities.

The correct answer provides that the ribbon should be installed at a depth of 30 inches. This depth is significant as it strikes a balance, allowing for adequate protection of the utilities and ensuring that the warning ribbon is easily detectable by anyone who may be digging in the area. By placing the ribbon at this specified depth, it helps to maintain awareness of the buried services without risking interference from the surrounding soil that might occur at shallower depths.

In contrast, the other depth options do not align with this requirement. Depths like 24, 36, or 42 inches either do not correspond to standard practices or could pose challenges in being visible for warning purposes. Thus, the 30-inch requirement effectively meets safety standards while allowing for practical excavation work around underground services.