What Is Shoring?
Shoring involves installing "supports along trench or excavation walls" to prevent cave-ins. This method directly reinforces trench walls rather than relying on sloping or shielding techniques.
When Is Shoring Required?
According to OSHA excavation standards:
- Required for trenches 5 feet or deeper unless soil is stable rock
- May be required for shallower trenches with loose or hazardous soil conditions
- A competent person must evaluate soil type and determine necessary protective systems
Types of Shoring Systems
Hydraulic Shoring Prefabricated aluminum hydraulic cylinders are placed against trench walls and pressurized to push plates against soil. These systems are quick to install and adjustable to various trench dimensions.
Timber Shoring Uses heavy wood planks supported by uprights and cross braces—a traditional method still employed on certain projects.
Aluminum Hydraulic Shoring with Plywood Combines aluminum cylinders with plywood sheeting for enhanced soil support. This approach is lightweight, portable, and effective across multiple soil types.
Screw Jack Shoring A mechanical alternative using adjustable screw jacks that requires manual adjustment but no hydraulic pump.
Step-by-Step Installation Process
- Soil Analysis - A competent person classifies soil as Type A, B, or C to determine spacing and sizing requirements
- System Selection - Choose appropriate shoring based on project needs and soil conditions
- Trench Preparation - Remove loose soil and ensure safe worker access with ladders within 25 feet
- Component Installation - Place uprights or cylinders against walls with proper cross-bracing
- Pressurization - Apply firm pressure via hydraulics or mechanical means
- Pre-Entry Inspection - Verify security and stability before workers enter
- Safe Removal - Exit workers first, release pressure gradually, and backfill promptly
OSHA Requirements
OSHA's excavation standard (29 CFR 1926 Subpart P) specifies maximum trench depths, spacing requirements, and soil-type specifications. Only a competent person may design, install, or inspect shoring systems.
Best Practices
- Combine shoring with access controls, traffic safety, and site protection
- Inspect shoring after heavy rain, vibrations, or soil changes
- Never allow workers in unprotected trenches
- Train employees on installation and hazard recognition
Frequently Asked Questions
Q: What is shoring in excavation? A: The process of supporting trench walls to prevent soil collapse.
Q: When is shoring required by OSHA? A: For trenches 5 feet or deeper, or shallower trenches with unstable soil.
Q: What are the main shoring system types? A: Hydraulic shoring, timber shoring, aluminum shoring, and screw jack systems.
Q: Who can install shoring? A: A trained competent person must oversee installation and inspection.
Q: How does shoring differ from shielding? A: Shoring supports walls while shielding (trench boxes) protects workers without supporting soil.
