Ontivity Resources

Excavation and trenching are among the most hazardous construction operations.  According to the U.S. Bureau of Labor Statistics, an average of 54 workers die in trenching or excavation cave-ins each year.  Hazards associated with trench work and excavations are recognized and preventable, yet injuries and fatalities associated with these hazards continue to occur.  Today we would like to talk are going to cover three items to help keep you safe while working with trenching and excavation while on site…

• Know the soil classification.

A Competent person must be onsite at all times to aid in soil classification and perform daily inspections.  There are four soil classifications which include: Stable Rock, Type A, Type B, and Type C.  Stable Rock is a Natural solid mineral matter that can be excavated with vertical sides and remain intact while exposed.  Type A soil is a cohesive soil with an unconfined compressive strength of 1.5 tons per square foot or greater.  Examples include clay, silty clay, sandy clay, and clay loam.  Type B soil is a cohesive soil with an unconfined compressive strength greater than 0.5 tons per square foot but less than 1.5 tons per square foot.  Examples include angular gravel like crushed rock, silt, silt loam, sandy loam and in some cases, silty clay loam and sandy clay loam.  Type C soil is a cohesive soil with an unconfined compressive strength of 0.5 tons per square foot or less.  Examples include gravel, sand, loamy sand, submerged soil, or soil from which water is freely seeping.

• Utilize the proper benching and shoring methods.

A form of benching or shoring must be used any time personnel must work in a trench or excavation 5 feet or greater.  A competent person must be onsite and examine the soil verifying that there are not any indications of a potential cave-in.  We must always limit the amount of time and work that is performed within the trench or excavation.  All spoils, materials, and equipment must be kept at a minimum, 2 feet away from the edge at all times.  Sloping and benching for excavations greater than 20 feet shall be designed by a registered professional engineer.  Stable Rock does not require any benching or shoring unless there are signs of a potential cave-in.  Type A soil requires a ¾:1 slope or a form of shoring while Type B soil requires a 1:1 slope or form of shoring.  Type C soil is often the most common in our area and requires a 1 ½:1 slope or form of shoring.  If a trench box is used, we must remember that all trench boxes must exceed 18 inches above vertical sides and the excavation must not exceed 2 feet below the bottom of the trench box.

• Provide safe access into and out of the excavation.

OSHA standards require a safe means of access and egress for personnel working in trench excavations 4 feet or greater such as a stairway, ladder, or ramp.  The means of egress must be located in such a manner that no worker must travel more that 25 feet laterally within the trench.  When using ladders as your means of access and egress, make sure the ladder extends three feet above grade and secure the ladder by tying it off with the use of rope and stakes.

EXTRAS:  It goes without saying that we must have a dig test performed before any trenching or excavation is started.  Dig test must not exceed 14 days in age otherwise it needs to be performed again.  All strikes must be immediately reported to safety.

If you would like more information on this topic or any other safety-related topic, please reach out to the Ontivity safety team at safety@ontivity.com, and we will get you taken care of.