Excavations and Trenching

Working in an excavation is one of the most hazardous jobs in the construction industry. Most excavation accidents are the result of cave-ins or collapsing excavation walls. There are, however, a number of procedures and protective systems designed to protect you in or around an excavation.

  • Never enter an unprotected trench.
  • Workers must be protected from cave-ins by an adequate protective system in trenches that are 5 feet deep or deeper.
  • A daily inspection of the excavation, adjacent areas, and protective systems by a competent person is required. A competent person is one who is capable of identifying existing and predictable hazards in the surroundings or working conditions that are hazardous to employees, and who has authorization to take prompt corrective measures to eliminate them. The competent person for excavations and trenching performed by the University is the Civil Engineering Manager or his designate. Reference the daily excavation checklist for a copy of the type of checklist that could be used by the competent person.
  • When used, sloping of the excavation walls must be adequate for the type of soil. A competent person must determine soil type.
  • Trench boxes or shields must be used in accordance with the manufacturer’s recommendations, or as designed and approved by a registered professional engineer.
  • Ramps, runways, ladders, or stairs must be used for access if the trench is greater than four feet deep. Access must be provided within 25 feet of a work area.
  • Any material or equipment, including spoil, that could fall or roll into an excavation must be placed at least two (2) feet from the edge of the excavation. All surface encumbrances that may create a hazard to workers must be removed or supported.
  • A registered professional engineer must design excavations that are more than twenty feet deep.
  • A warning system for pedestrian and vehicular traffic must be in place around all excavations. The warning system must consist of barricades, hand or mechanical signals, or stop logs and flashing lights at night.
  • Adequate protection from hazards associated with water accumulation must be in place before working in excavations.
  • Employees exposed to public vehicular traffic must be provided with and wear reflective warning vests.
  • Where workers or equipment are expected to cross over an excavation, walkways with standard guardrails must be provided.
  • Notify EHS at 609-258-5294 or the Program Manager for Facilities Operations Safety of any new excavation on campus.

Utility Mark-out (New Jersey One-Call System)

The State of New Jersey requires that the location of underground installations (e.g., sewer, telephone, electrical, fuel, natural gas, water and other lines, as well as underground tanks) must be identified and marked out prior to work that involves any digging operation. Activities covered by this requirement include, but are not limited to, excavations or trenching, blasting, installation of tents, sign posts, or fence posts, removing or planting of trees, or the planting of a new garden.

New Jersey One-Call must be contacted at 1-800-272-1000 at least three (3) full working days, but not more than ten (10) days, prior to the planned start date of the digging operations. In the event of an emergency (e.g., broken water line, etc.) that will require an excavation, the One-Call system operator must still be contacted. The One-Call system operator has an emergency response procedure that includes the immediate dispatch of mark-out technicians.  The Princeton University Civil Engineering Manager or his designate should also be contacted prior to conducting any digging operation on campus. The Civil Engineer is most familiar with all underground voids, steam tunnels, vaults, etc. that are located on campus.

New Jersey One Call System

Image Source:  New Jersey One Call - www.nj1-call.org/