Table of Contents
Trenches 5 feet (1.5 meters) deep or greater require a protective system unless the excavation is made entirely in stable rock. If less than 5 feet deep, a competent person may determine that a protective system is not required.
At what depth must an excavation be supported?
*Each country will have specific regulations. For example, OSHA in the United States still specifies a depth that trench shoring must be used, which is currently 5 ft or 1.5 metres deep. However, if the trench is less than this depth, a competent person must determine if a protective system is required.
How wide can a trench be without shoring?
How Deep Can a Trench Be Without Shoring? Trenches with a depth of 5 feet (1.5 meters) or greater need a protective system unless the entire excavation is in stable rock. If there is anything less than 5 feet, it is up to a competent person’s discretion to determine if there is a need for a protective system.
At what depth is trench support required?
Regulation 306 A person conducting a business or undertaking who proposes to excavate a trench at least 1.5 m deep, must ensure, so far as is reasonably practicable, that the work area is secured from unauthorised access (including inadvertent entry).
What is the minimum trench depth that requires shoring?
When trenches reach a depth of 5 feet or more, OSHA requires contractors to use a protective system. Protective systems are also required for trenches less than 5 feet deep if the soil might have the propensity to cave in when the trench is dug (such as with sand or mud).
What is the safest way to get into and out of a deep excavation?
Battering the excavation sides – Battering the excavation sides to a safe angle of repose may also make the excavation safer. In granular soils, the angle of slope should be less than the natural angle of repose of the material being excavated. In wet ground a considerably flatter slope will be required.
How do you protect deep excavation?
Those methods are sloping, benching, and shoring or shielding. Sloping: Sloping is a viable option as a protective system. Sloping is often the most cost-effective way to protect employees from potential trenching and excavation hazards.
What type of soil Cannot be benched?
Type C soil cannot be benched.
When a trench is 4 feet or more in depth?
OSHA requires employers to provide ladders, steps, ramps, or other safe means of egress for workers working in trench excavations 4 feet (1.22 meters) or deeper. The means of egress must be located so as not to require workers to travel more than 25 feet (7.62 meters) laterally within the trench.
When digging a trench a gas line hit can lead to an explosion?
– A gas line hit can lead to an explosion. – A broken water line can fill a trench in seconds. – Contact with buried power cables can kill. Safety Tip: Always your local utility locating service such as 811 before you dig, and get the utilities marked.
When should a trench be supported?
The basis of the rule is that, if a trench is under 1.2m deep, then people can enter the trench without the sides of the excavation being supported or battered back. This rule is no longer something that should be considered. 1.2m is no longer the threshold for the need to support an excavation.
How do you stop a trench from collapsing?
Trench collapse risks can be minimized by shifting the soil weight away from the trench opening. Trench collapses can also be minimised by placing trench sheets on both sides of the trench.
Is code for excavation working space?
4.13 No excavation or earthwork below the level of any foundation of building or structure shall be commenced or continued unless adequate steps are taken to prevent danger to any person employed, from collapse of the structure or fall of any part thereof.
Which type of soil is the least stable?
Type C soil is the least stable type of soil. Type C includes granular soils in which particles don’t stick together and cohesive soils with a low unconfined compressive strength; 0.5 tons per square foot or less. Examples of Type C soil include gravel, and sand.
Which type of soil is the most cohesive?
Clay is a very fine grained soil, and is very cohesive. Sand and gravel are course grained soils, having little cohesiveness and often called granular. Generally speaking, the more clay that is in the soil being excavated, the better the trench walls will hold up. Another factor in soil cohesiveness is water.
What are the three main protection methods against cave-ins?
To prevent cave-ins: SLOPE or bench trench walls. SHORE trench walls with supports, or. SHIELD trench walls with trench boxes.
What is most likely to cause an excavation to collapse?
Excavated spoil, plant or materials should not be stored close to the sides of excavations as loose material can fall in. The extra loading can make the sides of the excavation more likely to collapse. Prevent people from falling into excavations by substantial barriers around the edges.
What are the problems that occur during deep excavation?
Various defects occur during construction in deep excavations such as leakage through retaining wall, dewatering during excavation, retaining wall construction, pulling out used pile and over excavation.
What is benching in excavation?
“Benching (Benching system)” means a method of protecting employees from cave-ins by excavating the sides of an excavation to form one or a series of horizontal levels or steps, usually with vertical or near-vertical surfaces between levels.
How do you prevent soil collapse during excavation?
Soil collapse in a trench can be prevented either by side slope or by benching of side wall or by shoring.
What is considered a deep excavation?
Deep excavations, on the other hand, are defined as being any excavation which is more than 4.5 metres in depth – a considerable height indeed. Deep excavations are trickier to plan and implement than shallow excavations, for a variety of reasons, which is why they tend to only be carried out by trained professionals.
When should shoring be installed?
All shoring should be installed from the top down and removed from the bottom up. Hydraulic shoring should be checked at least once per shift for leaking hoses and/or cylinders, broken connections, cracked nipples, bent bases, and any other damaged or defective parts. FIGURE V:2-8.
