Construction Site Safety Concern: Trenches and Excavations Part II

Excavating is a common activity on construction projects which can create dangerous situations for employers, employees, and bystanders.  Because of the many dangers involved in excavating and trenching, OSHA has many rules around these activities including the concerns involving an excavation and trench.  Walden discussed some general excavating and trenching rules in our previous blog Construction Site Safety Concern: Trenches and Excavations Part I.

Safety Feature Support Systems

Once a trench or excavation is greater than five (5) feet, the excavation requires additional safety feature support systems to prevent cave-ins.  To clarify, if your excavation is 4 feet 11 inches deep, the excavation does not require an additional protection system.  If your excavation is 5 feet or greater in depth, your excavation will require a safety feature support system to prevent collapsing.  The only exception for excavations greater than 5 feet requiring support systems is when the excavation is made ENTIRELY in stable rock, in which case OSHA does not require additional excavation support.  It is not common for excavation to be made in stable rock, so most excavations 5 feet or deeper require additional safety feature support systems.

Sloping and Benching

One method of protection is sloping and benching the walls of the excavation or trench.  The slope or bench method used is determined based on the excavation soil type, tabulated data, and/or is designed by a registered professional engineer.  The area surrounding the sloped or benched excavation should be kept clear.  No equipment or materials should be stored close to the edge.  In addition, work should not be conducted close to the edge of the excavation as a safety feature unless the employees within the excavation are protected from falling or sliding material.

Design Support System

Most construction projects don’t have the space for sloping and benching or they do not want to disturb more area than is required.  In those cases, the excavation can be supported with a designed support system.  These can include wood sheeting, aluminum hydraulic sheeting, pre-fabricated sheeting (e.g. trench box), or other proper safety feature support system.  These systems must still be designed using OSHA appendices, manufacturer’s tabulated data, and/or design by a registered professional engineer.

Additional Safety Precautions

All safety feature protective systems in place shall have the capacity to resist all loads that are intended or could be expected to be applied to the excavation.  Any materials or equipment used to protect an excavation must be in good condition.  No apparent damage or defects within the equipment is allowed.  A “competent person” must inspect and determine all equipment and materials are suitable for use.  A “competent person” is someone who is able to identify hazards in the work area and has the authority to remove or eliminate those hazards.  All support systems installed shall be secured and ensured not to slide, fall, or fail by other means.  When removing the support systems, measures must be taken to ensure no harm to workers.

Walden has worked with and for contractors to ensure OSHA and construction safety compliance or over 22 years.  Walden can help keep your construction project safe while ensuring it is completed on schedule and within budget.  If you have any questions or require any additional information on trenching and excavating rules or regulations please call Walden at (516) 624-7200.

 

 

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