ANSI A10.12 – 1998 (R2004) Background Materials

Title: Safety Requirements for Excavation

Scope: This standard applies to all open excavations made in the earth’s surface that require worker and/or property protection. Excavations are defined to include trenches.

Table of Contents:

SECTION
PAGE
1. Scope, Application and Definitions Applicable to this Standard
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1.1 Scope and Application
1.2 Definitions
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2. General Requirements
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2.1 Owner’s Responsibilities
2.2 Contractor’s or Subcontractor’s Responsibilities
2.3 Excavation Competent Person’s Responsibilities
2.4 Surface Encumbrances
2.5 Underground Installations
2.6 Access and Egress
2.7 Exposure to Vehicular Traffic
2.8 Exposure to Falling Loads
2.9 Warning System for Mobile Equipment
2.10 Hazardous Atmospheres
2.11 Protection from Hazards Associated with Water Accumulation
2.12 Stability of Adjacent Structures
2.13 Protection of Employees from Loose Rock or Soil
2.14 Inspections
2.15 Fall Protection

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3. Requirements for Protective Systems
 

3.1 Protection of Employees in Excavations
3.2 Design of Sloping and Benching Systems

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3.3 Design of Support Systems, Shield (Trench Box) Systems,
       and Other Protective Equipment
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3.4 Materials and Equipment
3.5 Installation and Removal of Support
3.6 Sloping and Benching Systems
3.7 Shield (Trench Box) Systems
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APPENDIXES

A Soil Classification

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A1 Scope and Application
A2 Definitions
A3 Requirements
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A3.1 Classification of Soil and Rock Deposits
A3.2 Basis for Classification
A3.3 Visual and Manual Analysis
A3.4 Layered Systems
A3.5 Reclassification
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A4 Acceptable Visual and Manual Tests
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A4.1 Acceptable Visual Analysis
A4.2 Acceptable Manual Test
A4.3 Other Strength Tests
A4.4 Drying Test

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B Sloping and Benching

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B1 Scope and Application
B2 Definitions

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B3 Requirements
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B3.1 Soil Classifications
B3.2 Maximum Allowable Slope
B3.3 Actual Slope
B3.4 Configurations
B3.5 Excavations Made in Type A Soil
B3.6 Excavations Made in Type B Soil
B3.7 Excavations Made in Type C Soil
B3.8 Excavations Made in Layered Soil

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C Timber Shoring for Trench Excavations

 

C1 Scope
C2 Soil Classification
C3 Presentation of Information
C4 Basis and Limitations of the Data
C4.1 Dimensions of Timber Members
C4.2 Limitation of Application
C5 Use of Tables
C6 Examples to Illustrate the Use of Tables C1-C3
C7 Notes for Appendix C Tables

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D Aluminum Hydraulic Shoring for Trenches

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D1 Scope
D2 Soil Classification
D3 Presentation of Information
D4 Basis and Limitations of the Data
D5 Use of Tables D1-D4
D6 Examples to Illustrate the Use of the Tables
D7 Notes for Tables D1-D4

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E Alternative Worker Protection Systems
F Selection of Protection Systems

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TABLES
B1 Maximum Allowable Slopes
C1 Timber Trench Shoring – Minimum Timber
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Requirements Soil Type A
C2 Timber Trench Shoring – Minimum Timber
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Requirements Soil Type B
C3 Timber Trench Shoring – Minimum Timber
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Requirements Soil Type C
C4 Timber Trench Shoring – Minimum Timber
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Requirements Soil Type A
C5 Timber Trench Shoring – Minimum Timber
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Requirements Soil Type B
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C6 Timber Trench Shoring – Minimum Timber
Requirements Soil Type C
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D1 Aluminum Hydraulic Shoring, Vertical Shores, For Soil Type A
D2 Aluminum Hydraulic Shoring, Vertical Shores, For Soil Type B
D3 Aluminum Hydraulic Shoring, Water Systems, For Soil Type B
D4 Aluminum Hydraulic Shoring, Water Systems, For Soil Type C

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FIGURES
B1 Simple Slope – Type A
B2 Simple Slope – Short-Term
B3 Simple Bench
B4 Multiple Bench
B5 Supported or Shielded Vertically Sided Lower Portion
B6 Simple Slope – Type B
B7 Simple Bench
B8 Multiple Bench
B9 Vertically Sided Lower Portion
B10 Simple Slope – Type C
B11 Vertical Sided Lower Portion
B12 B Over A
B13 C Over A
B14 C Over B
B15 A Over B
B16 A Over C
B17 B Over C
D1 Vertical Aluminum Hydraulic Shoring (Spot Bracing)
D2 Vertical Aluminum Hydraulic Shoring (With Plywood)
D3 Vertical Aluminum Hydraulic Shoring (Stacked)
D4 Aluminum Hydraulic Shoring Water System (Typical)
E1 Aluminum Hydraulic Shoring
E2 Pneumatic/Hydraulic Shoring
E3 Trench Jacks (Screw Jacks)
E4 Trench Shields
F1 Preliminary Decisions
F2 Sloping Options
F3 Shoring and Shielding Options
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