How many times do we see utility workers, sewer workers or construction workers working unprotected in trenches?

Trenches literally are filled with a variety of potential safety and environmental hazards. Cave-ins perhaps are the most feared trenching hazard as one cubic yard of soil can weigh as much as a car. Asphyxiation due to lack of oxygen in a confined space is a major risk. So are inhalation of toxic fumes and drowning.