Selecting a Shoring System
Shoring Systems actually preload the trench walls and provide a positive restraint to soil movement. Some of the advantages would include:
|
|
|
Shielding Systems are not designed to prevent trench wall collapse, but serve instead to “shield” the workers within the shielding system itself. Some of the advantages would include:
|
|
|
Information to know when ordering:
|
|
|
Facts
Excavations over 4 feet deep or in unstable soil must be shored according to WISHA. OSHA standard is 5’ deep.
Excavation of material may extend 2 feet below the bottom of a shield only if the shield is designed for the full depth of the trench and there is no evidence of soil loss from below the bottom of the shield.
ISHA/OSHA allows the use of 1 1/8” plywood or 3/4” Finform sheeting in conjunction with hydraulic shoring.
Vertical shoring can be used in C60 soil type when the manufacturers tabulated date allows for it.
Pre-engineered shoring systems can be used in trenches over 20’ deep when the manufacturers tabulated data allows for it.
Definitions
Tabulated Data
Tables and charts approved by a registered professional engineer. These tables and charts provide information on the shoring capabilities.
Competent Person:
One who is capable of identifying predictable hazards and who has the authority to take corrective measures to eliminate them.
Soil Classification:
Method of classifying soils based on environmental
conditions. This must be completed by the competent person.
Type A: Cohesive soils with an unconfined compressive strength of 1.5 TSF or greater. Examples would be dry stable material such as clay, silty clay loam, and cemented soils.
Type B: Cohesive soil with an unconfined compressive strength of 0.5 TSF, but less than 1.5 TSF. Examples would be dry to moist soils, clays, and gravels.
Type C: Cohesive soil with an unconfined compressive strength of 0.5 TSF or less. Examples would be some granular or submerged soils.
Shoring
