Trenches running parallel to a footing shall not extend below what angle to the bearing plane of the footing?

The correct choice is based on the requirement that trenches running parallel to a footing must maintain a safe angle to prevent undermining the structural integrity of the footing. The Omaha Plumbing Code specifies that trenches should not extend below a 45-degree angle from the bearing plane of the footing. This angle is critical because it establishes a safeguard against excessive soil erosion and ensures that the footing remains properly supported.

When trenches are dug at an angle steeper than 45 degrees in relation to the bearing plane, there is a higher risk of instability. This could lead to settlement or even failure of the footing if the earth surrounding it is compromised. Therefore, maintaining a trench at or above this angle protects not only the plumbing work being performed but also the overall safety and structure of the building.

Other angles, such as 35 degrees, 60 degrees, or 90 degrees, do not align with the necessary safety practices outlined in the plumbing code for trenching near footings. A 90-degree angle, for instance, would mean that the trench is directly adjacent to the footing without any safety buffer, potentially resulting in a collapse of the soil around the foundation.