Safety procedures for trenching and excavation work are essential to prevent cave-ins and ensure worker safety, complying with OSHA regulations. These procedures include sloping, shoring, and using protective systems.

Before beginning any excavation work, several factors must be considered to determine the appropriate protective system:

• Soil type
• Depth of cut
• Water content of the soil (changes due to weather or climate)
• Surcharge loads (spoil, materials, other operations in the area) [1]

OSHA requires that each employee in an excavation shall be protected from cave-ins by an adequate protective system designed in accordance with OSHA regulations, except when: 1. Excavations are made entirely in stable rock; or 2. Excavations are less than 5 feet (1.52 m) in depth and examination of the ground by a competent person provides no indication of a potential cave-in. [6]

The two basic methods of protecting workers against cave-ins are sloping and temporary protective structures. [1]

## Sloping Sloping involves cutting back the trench wall at an angle inclined away from the excavation. The angle of slope depends on the soil conditions. [1]

Maximum allowable slopes for excavations less than 20 feet deep are:

• Stable Rock: Vertical (90°)
• Type A Soil: 3/4:1 (53°)
• Type B Soil: 1:1 (45°)
• Type C Soil: 1 1/2:1 (34°) [5]

## Shoring Shoring is a system that supports the sides or walls of a trench. It involves installing aluminum, steel, or wood panels supported by screws or hydraulic jacks. [1]

## Trench Boxes Trench boxes are commonly used in open areas away from utilities, roadways and foundations. They are designed to protect workers from cave-ins but not to shore up or support trench walls unless properly backfilled and compacted. [3]

Regular inspections are crucial. A competent person must inspect the excavation at the start of each shift, before work begins, and after any event that could affect the strength or stability of the excavation. [2]

It is essential to identify the soil type(s) related to the excavation, as soil properties can vary widely within a single trench. [4]

Before digging, it is important to locate all buried services and contact the owners of any underground utilities to identify and mark their locations. [4]

Other safety considerations include:

• Ensuring proper barriers or guardrails are in place to prevent falls into the excavation.
• Testing the air in the excavation for low oxygen, hazardous gases, and vapors.
• Providing a safe means of entry and exit, such as a secured ladder within 25 feet of all workers.
• Ensuring workers wear appropriate PPE, including hard hats, safety boots, and high-visibility vests. [2]

Excavated materials and equipment should be placed at least 1 meter (3.3 feet) away from the edge of the excavation. [2]

Always check the legislative requirements related to the use of protective systems in your jurisdiction. [1]

By following these procedures, employers can create a safer work environment and reduce the risk of cave-ins and other excavation-related hazards.