Under Massachusetts General Law Chapter 82A and the associated Trench Safety Regulations (520 CMR 14.00), a trench is defined as "An excavation that is narrow in relation to its length, made below the surface of the ground, and that is deeper than 3 feet."
There are strict safety requirements when works with trenches:
Before starting any trenching work deeper than 3 feet, an Excavation & Trench Permit must be obtained. The permit ensures compliance with safety standards designed to protect workers and the public from hazards associated with trenching operations. Any individual, contractor, or entity planning to excavate a qualifying trench must secure a permit, regardless of whether the trench is on private or public property. Certain excavations may be exempt, such as Emergency utility restoration. However, safety regulations still apply even if a permit is not required.