What is a trench?

According to M.G.L. c. 82A, §4 and 520 CMR 14.02, a trench is defined as "an excavation which is narrow in relation to its length, made below the surface ground in excess of three feet below grade and the depth of which is, in general, greater than the width, but the width of the trench, as measured at the bottom, is not greater th an 15 feet."  Learn more about trench safety.