Somewhat related to this is the regulations for interstate natural gas pipelines. The regs have four “classes” which dictate the thickness and depth of a pipeline based on the diameter and pressure of the pipe.

Those “classes” are determined by population density near the pipe eg high density means thicker pipe.

This means city dwellers get the biggest safety margin, while those out in rural regions get pipelines that are around 50% thinner. And such pipelines can be within a few feet of an occupied dwelling.