keep excavated dirt, rocks, and other materials back two feet from the excavation's edge. whose responsibility is this?

The responsibility to keep excavated dirt, rocks, and other materials at least two feet back from the edge of an excavation is assigned to the employer as part of their duty to provide a safe work environment and implement proper excavation safety controls.

Workers are expected to follow these safety rules on site, but the primary accountability for establishing, enforcing, and planning this control (including training, supervision, and procedures) rests with the employer.