Helping contractors to promote safe work practices for the protection of workers and utilities in trenching and excavation operations is an industry imperative. Developed from United Rentals’ extensive experience in trench safety projects, this article may assist companies to properly use trench protective systems by following manufacturers’ tabulated data.
Trench and excavation operations are among the most dangerous jobs in the construction and utility industries. While most trench fatalities happen in unprotected trenches, studies from the Bureau of Labor Statistics estimate that 24 percent occur when sloping, benching, shielding or shoring is used improperly. In these tragic incidents, often times OSHA tables and charts for sloping, benching, timber shoring or manufactured systems with tabulated data using shields or shoring are not being followed.
Trench shoring and protection systems can be used at these worksites to help keep workers safe and protected from cave-ins. These systems come with manufacturers’ tabulated data that typically consists of tables, charts and other information created by a registered professional engineer. The tabulated data guides companies in choosing, assembling and installing a trench protective system. OSHA regulation 1926.650 requires companies have a competent person at every excavation in charge of overseeing all aspects of the excavation, including inspecting trenches, identifying potential hazards, and mandatory selection of a protective system when the depths are 5 feet or greater.
There are a variety of protective systems available and when choosing the best protective system for a particular job site one needs to consider many conditions like the stability of soils, existing utilities, overall site conditions, adjacent structures to name a few. It’s important the competent person understand the tabulated data for each one the contractor wants to use. Too often, that understanding is missing and can lead to a serious injury or fatality. A survey distributed by United Rentals for the Center for Construction Research and Training in 2019 revealed more than 40 percent of respondents had trouble with tabulated data and the installation and use of protective systems.
Here are tips for using a manufacturer’s tabulated data properly with a trench protective system. Please consult a qualified individual for the needs and requirements of your specific job site.
Follow depth ratings
Manufacturer’s tabulated data contains charts and tables that dictate whether a protective system can be used at certain depths and under certain conditions. OSHA does not allow contractors to use a system outside of these parameters unless there was prior approval from the manufacturer or a registered professional engineer approved that usage in writing.
Look beyond charts and tables
In addition to charts and tables, manufacturer’s tabulated data includes instructions for safe and appropriate use of a protective system. Contractors need to take time to understand all the information provided by a manufacturer otherwise they may misuse the equipment. For example, if a contractor wants to use a system that includes parts from two or more manufacturers, the competent person must check the manufacturers’ instructions to determine whether doing so is permissible.
Know similar systems are not the same
A lack of industry-wide standards means even for the same type of protective system, tabulated data will differ among manufacturers. The competent person must review tabulated data for each system considering factors such as:
- Surcharge loads
- Allowances for soil types
- Dewatering limits
- Limitations on depths with vertically sided lower portions
- Time limitations on use of the system
Account for changing conditions
Manufacturer’s tabulated data must be kept on the jobsite during construction because conditions can change quickly. A sudden downpour, for example, may affect soil conditions or flood the trench. After such an event, and on a daily basis, the competent person must conduct inspections of the site and refer to the tab data to ensure use of the protective system still falls within the limits of safe operation. These checks are also needed when the trench becomes wider or deeper, when more pipe clearance is needed and when the contractor is using a shield and sloping out the sides of the trench.
The bottom-line is manufactured protective systems can save lives at trench and excavation worksites when they are used properly. Understanding and following all the requirements spelled out in tabulated data takes time and effort. As a best practice, teams should consult experts before beginning a trench or excavation project and follow proper safety protocols, including wearing the appropriate PPE. It’s the competent person’s responsibility and duty to safeguard employees working in a trench or excavation and return home each day unharmed.
Joe Wise is the Regional Customer Training Manager for the Trench Safety business unit of United Rentals. In his role, he provides strategic oversight to competent person training programs in confined space, excavation safety and others. With a team of safety training professionals who deliver training across North America, he oversees design and development to existing programs to enhance classroom and online learning experiences for worker safety education. Joe has been with United Rentals for 17 years and during this time has served in various leadership positions to educate contractors on compliance and protective system solutions for trench/excavation and confined space operations