Shepherd Construction was the general contractor on a job site to build a retail store. There were no other general contractors on the job site. Shepherd hired a plumbing company to install the pipes at the job site. A Shepherd employee was killed when the dirt walls fell on him as he was digging the holes for the building foundation. A plumber was in the hole and was also killed. Explain the application of OSHA in conjunction with the fact pattern. Analyze and evaluate the potential causes of action and liability, if any, of Shepherd, the retail store, and the plumbing company for the deaths that took place at the job site.