What's the difference between a trench and an excavation? An excavation is a hole left in the ground as the result of removing material. A trench is an excavation in which the depth exceeds the width.
An unstable trench or excavation can collapse, killing or injuring workers by suffocation or crushing when a worker is buried by falling soil. Trench stability is affected by a number of factors such as:
The risk of a cave-in is not the only hazard in trenching. Injuries and deaths are also related to six other major areas:
Before excavating, the gas, electrical, and other services in the area must be accurately located and marked. If the service poses a hazard, it must be shut off and disconnected. Over half of all powerline contacts involve buried cable.
There are three basic methods of protecting workers against trench cave-ins:
Most fatal cave-ins occur on small jobs of short duration such as service connections and excavations for drains and wells. Too often people think that these jobs are not hazardous enough to require safeguards against collapse. Unless the walls are solid rock, never enter a trench deeper than 1.2 metres (4 feet) if it is not properly sloped, shored, or protected by a trench box.
Part III (sections 222 to 242) of the Construction Regulation applies to all excavating and trenching operations. It identifies the various types of soils and specifies the type of shoring and timbering to be used for each. It spells out the precautions that must be taken before an excavation is begun and the requirements for trench support systems that must be designed by a professional engineer.
A reminder to call Ontario One Call or contact the utilities in the area before excavating a site.
Contains everything you need to recognize and protect yourself against construction health and safety hazards. 350 pages. Revised, Nov 2010.
A comprehensive safety manual, similar to Construction Health and Safety Manual (M029), developed for six trades: boilermakers, millwrights, refrigeration and air-conditioning mechanics, pipe trades, sprinkler and fire protection trades, and insulators. Jan 2009 ed.
Pocket-sized card showing excavator handsignals. 4¼” x 2¾”. Two-sided.
The catalogue features a comprehensive list of the products, training, auditing, and consulting services we offer, along with descriptions, images, and prices. Also includes a training registration form and product order form. 2010 edition.
This DVD covers all major hazards and safeguards involved in trenching operations. The main focus is on preventing and protecting against cave-ins, but it also explains sloping, shoring, and trench boxes in detail. 27 minutes. Colour.
This advisory contains helpful information for the excavator about locating underground utilities before starting to dig. 1 page.
The Safety Talks manual covers a wide variety of safety topics for the construction industry. By presenting the information in a concise and easily digestible format, you can prevent an injury or save a life in just 5 minutes. Revised May, 2008.
The Trenching Safety manual provides an introduction to trenching hazards. Contents include: soil types, causes of cave-ins, protection and safeguards, and emergency procedures. 32 pages. Revised, Nov 2010.
This safety meeting package contains everything you need to conduct a multimedia safety meeting. Conveniently available on CD, this package contains an electronic slideshow presentation on Trenching, facilitator's notes and a quiz on the content of the presentation.
