Excavations and Trenching l 29 CFR 1926 Subpart

Excavations and Trenching l 29 CFR 1926 Subpart P Presented by: ETTA, OSH Division, 919 -807 -2875 This presentation was created by the N. C. Department of Labor for safety and health training.

Objectives 1926 Subpart P l In this course, we will discuss the following: - Excavations/Trenching: Subpart P » 1926. 650 - Scope, application, and definitions applicable to this subpart » 1926. 651 - Specific excavation requirements » 1926. 652 - Requirements for protective systems This presentation was created by the N. C. Department of Labor for safety and health training.

Subpart P - Appendices 1926 Subpart P l Appendix A - Soil Classification l Appendix B - Sloping and Benching l Appendix C - Timber Shoring for Trenches l Appendix D - Aluminum Hydraulic Shoring l Appendix E - Alternatives to Timber Shoring l Appendix F - Selection of Protective Systems This presentation was created by the N. C. Department of Labor for safety and health training.

Definitions 1926. 650(b) l Excavation - Man-made cut, cavity, trench, or depression in an earth surface, formed by earth removal l Trench - Narrow excavation - Depth is greater than the width, but not wider than 15 feet l Shield (Shield system) - Structure able to withstand a cave-in and protect employees This presentation was created by the N. C. Department of Labor for safety and health training.

Definitions 1926. 650(b) l Shoring (Shoring system) - Structure that supports the sides of an excavation and protects against cave-ins l Sloping (Sloping system) - Technique that employs a specific angle of incline on the sides of the excavation l Tabulated Data - Tables and charts approved by a registered professional engineer (RPE) and used to design and construct a protective system This presentation was created by the N. C. Department of Labor for safety and health training.

Definitions 1926 Subpart P, Appendix A l Unconfined Compressive Strength - Load per unit area at which soil will fail in compression. It can be determined by laboratory testing, or estimated in the field using a pocket penetrometer, by thumb penetration tests, or by other methods. This presentation was created by the N. C. Department of Labor for safety and health training.

Definitions 1926. 650(b) l Competent person - Authority to take prompt corrective measures to eliminate existing and predictable hazards and to stop work when required - Ability to detect: » Conditions that could result in cave-ins » Failures in protective systems » Hazardous atmospheres » Other hazards including those associated with confined spaces - Should have training, experience and/or knowledge of: » Soil classification » Use of protective systems » Requirements of the standard NCDOL Photo Library This presentation was created by the N. C. Department of Labor for safety and health training.

Weight of Soil l Weight of soil varies with type and moisture content l One cubic foot weighs 110 pounds to 140 pounds l One cubic yard (27 cubic feet) of soil can weigh more than 3, 000 pounds This presentation was created by the N. C. Department of Labor for safety and health training.

Excavation Hazards l Cave-ins are the greatest risk l Other hazards include: - Asphyxiation due to lack of oxygen - Inhalation of toxic materials/fumes - Water accumulation - Machinery moving near edge of excavation causing a collapse - Severing underground utility lines - Falls This presentation was created by the N. C. Department of Labor for safety and health training.

Injury and Death l Excavating is one of the most hazardous construction operations NCDOL Photo Library l Most accidents occur in trenches 5 - 15 feet deep l Usually no warning before a cave-in This presentation was created by the N. C. Department of Labor for safety and health training.

Specific Excavation Requirements l (a) Surface encumbrances l (b) Underground installations l (c) Access and egress l (d) Exposure to vehicular traffic l (e) Exposure to falling loads l (f) Warning system for mobile equipment l (g) Hazardous atmospheres This presentation was created by the N. C. Department of Labor for safety and health training.

Specific Excavation Requirements l (h) Protection from hazards associated with water accumulation l (i) Stability of adjacent structures l (j) Protection of employees from loose rock or soil l (k) Inspections l (l) Walkways This presentation was created by the N. C. Department of Labor for safety and health training.

Surface Encumbrances 1926. 651(a) l All surface encumbrances that create a hazard to employees must be removed or supported to safeguard employees This presentation was created by the N. C. Department of Labor for safety and health training.

Underground Installations 1926. 651(b)(1) l Estimated location of utility installations (sewer, telephone, fuel, electric, water lines) must be determined prior to opening an excavation This presentation was created by the N. C. Department of Labor for safety and health training.

Underground Installations 1926. 651(b)(2) l When utility companies or owners cannot respond to a request to locate underground utility installations within 24 hours - Employer may proceed with caution, provided detection equipment, or other acceptable means, is used to locate utility installations - Use ‘pot-holing’ technique This presentation was created by the N. C. Department of Labor for safety and health training.

Underground Installations 1926. 651(b)(3) l Exact location of underground installations must be determined by safe and acceptable means l Underground installations must be protected, supported or removed as necessary to safeguard employees This presentation was created by the N. C. Department of Labor for safety and health training.

Egress - Trench Excavation 1926. 651(c)(2) l Stairway, ladder, ramp, or other safe means of egress must be located in trench l Required if trench 4 feet or more in depth NCDOL Photo Library l Lateral travel distance no more than 25 feet This presentation was created by the N. C. Department of Labor for safety and health training.

Egress - Trench Excavation 1926. 651(c)(2) NCDOL Photo Library This presentation was created by the N. C. Department of Labor for safety and health training.

Egress - Trench Excavation l Is this correct? NCDOL Photo Library This presentation was created by the N. C. Department of Labor for safety and health training.

Exposure to Falling Loads 1926. 651(e) l Employees must not be permitted to work under loads handled by lifting or digging equipment NCDOL Photo Library This presentation was created by the N. C. Department of Labor for safety and health training.

Exposure to Falling Loads 1926. 651(e) l Stand away from equipment that is being loaded or unloaded l Equipment operators may stay in their equipment during loading and unloading if equipment has proper cab shield or canopy This presentation was created by the N. C. Department of Labor for safety and health training.

Warning System - Mobile Equipment 1926. 651(f) l Mobile equipment operated adjacent to excavation and operator cannot see edge of the excavation: - Warning system must be utilized » Barricades » Hand or mechanical signals » Stop logs NCDOL Photo Library This presentation was created by the N. C. Department of Labor for safety and health training.

Hazardous Atmospheres 1926. 651(g)(1) l Where a hazardous atmosphere exists or could reasonably be expected to exist, testing shall be conducted before employees enter the trench and regularly thereafter - Less than 19. 5% or more than 23. 5% oxygen - A combustible gas concentration greater than 20% of the Lower Flammable Limit (LFL) - Concentrations of hazardous substances that exceed OSHA’s Permissible Exposure Limits (PEL) This presentation was created by the N. C. Department of Labor for safety and health training.

Hazardous Atmospheres 1926. 651(g)(1) l Test at 4 feet if suspected - Lower explosive limit (LEL) - Oxygen - Carbon monoxide - Hydrogen sulfide - Petroleum - Other toxics NCDOL Photo Library This presentation was created by the N. C. Department of Labor for safety and health training.

Emergency Rescue Equipment 1926. 651(g)(2)(i) l Emergency rescue equipment must be readily available where hazardous atmospheric conditions exist or expected to develop during work - Breathing apparatus - Safety harness and line - Basket stretcher This presentation was created by the N. C. Department of Labor for safety and health training.

Water Accumulation 1926. 651(h) l Employees must not work in excavations where there is accumulated water, or where water is accumulating l Unless precautions taken to protect workers: - Water removal to control level of water - Special support or shield systems l Excavations subject to runoff from heavy rains require an inspection by a competent person This presentation was created by the N. C. Department of Labor for safety and health training.

What are the hazards? NCDOL Photo Library This presentation was created by the N. C. Department of Labor for safety and health training.

What are the hazards? NCDOL Photo Library This presentation was created by the N. C. Department of Labor for safety and health training.

Stability of Adjacent Buildings 1926. 651(i)(1)-(2) l Support systems such as shoring, bracing, or underpinning must be provided to ensure stability of structures l Excavation below the foundation that could pose a hazard shall not be permitted except: l ‘ - Underpinning provided - Stable rock - RPE approval This presentation was created by the N. C. Department of Labor for safety and health training.

Underpinning 1926. 651(i)(2)(i) l Underpinning to prevent structural failure NCDOL Photo Library This presentation was created by the N. C. Department of Labor for safety and health training.

Protection of Employees 1926. 651(j)(1) l Adequate protection provided to protect employees from loose rock or soil that could pose a hazard by falling or rolling from an excavation face This presentation was created by the N. C. Department of Labor for safety and health training.

Potential Problems This presentation was created by the N. C. Department of Labor for safety and health training.

Protection of Employees 1926. 651(j)(2) l Employees must be protected from equipment or materials that could fall or roll into excavations - Materials and equipment must be kept 2 feet from edge of excavation or use retaining devices NCDOL Photo Library This presentation was created by the N. C. Department of Labor for safety and health training.

Rule: 2 Feet 1926. 651(j)(2) This presentation was created by the N. C. Department of Labor for safety and health training.

Two Feet From Edge 1926. 651(j)(2) NCDOL Photo Library This presentation was created by the N. C. Department of Labor for safety and health training.

Inspections – Competent Person 1926. 651(k)(1) l Daily l Before the start of each shift and as needed throughout the shift l After every rain storm and other events that could increase hazards; e. g. , snowstorm, windstorm, thaw, earthquake This presentation was created by the N. C. Department of Labor for safety and health training.

Protection of Employees 1926. 652(a)(1) l Employees in an excavation must be protected NCDOL Photo Library from cave-ins by adequate protective system - Except when: » Made entirely in stable rock » Excavation is less than 5 feet deep and examined by competent person NCDOL Photo Library This presentation was created by the N. C. Department of Labor for safety and health training.

Methods of Protection 1926. 652 l Sloping and benching l Shoring (spaced sheeting, closed sheeting) l Trench shield l Other occasionally used systems This presentation was created by the N. C. Department of Labor for safety and health training.

Protective Systems 1926. 652(a)(2) l Protective systems shall have capacity to resist, without failure, all loads applied or transmitted to the system NCDOL Photo Library USDOL Photo Archive This presentation was created by the N. C. Department of Labor for safety and health training.

Installation and Removal 1926. 652(e)(1)-(2) l Support systems must be installed and removed in a manner that protects employees from cave-ins l Removal must begin at, and progress from, the bottom of the excavation l Members released slowly to note any indication of possible failure of remaining members l Excavations of material to a level not greater than 2 feet below the bottom of the support system or shield, must not be permitted This presentation was created by the N. C. Department of Labor for safety and health training.

What’s the hazard? 1926. 652(g)(2) This presentation was created by the N. C. Department of Labor for safety and health training.

What’s the hazard? NCDOL Photo Library This presentation was created by the N. C. Department of Labor for safety and health training.

Soil Classification Appendix A l Contains definitions l Sets forth requirements l Describes acceptable visual and manual test for use in classifying soils This presentation was created by the N. C. Department of Labor for safety and health training.

Definitions Appendix A l Cohesive soil - Clay, or soil with a high clay content, which has cohesive strength » Does not crumble » Can be excavated with vertical side slopes » Plastic when moist » Hard to break up when dry This presentation was created by the N. C. Department of Labor for safety and health training.

Definitions Appendix A l Granular soil - Gravel, sand, or silt, with little or no clay content » No cohesive strength » Cannot be molded when moist » Crumbles easily when dry Note: Some moist granular soils exhibit apparent cohesion This presentation was created by the N. C. Department of Labor for safety and health training.

Definitions Appendix A l Unconfined compressive strength - Load per unit area at which a soil will fail in compression Note: Estimated in the field by use of a pocket penetrometer, thumb penetration test, and other methods This presentation was created by the N. C. Department of Labor for safety and health training.

Type A Soil Appendix A l Most stable: clay, silty clay, and hardpan l Not fissured l Not subjected to vibration of any type l Never been previously disturbed l No seeping water This presentation was created by the N. C. Department of Labor for safety and health training.

Type B Soil Appendix A l Medium stability: silt, sandy loam, medium clay and unstable dry rock l Previously disturbed soils unless otherwise classified as Type C l Soils that meet the requirements of Type A but are fissured or subject to vibration This presentation was created by the N. C. Department of Labor for safety and health training.

Type C Soil Appendix A l Least stable: gravel, loamy sand, soft clay l Submerged soil or dense, heavy unstable rock l Soil from which water is freely seeping This presentation was created by the N. C. Department of Labor for safety and health training.

Sloping and Benching Appendix B l Contains definitions l Sets forth requirements l Configurations of sloping and benching This presentation was created by the N. C. Department of Labor for safety and health training.

Summary 1926 Subpart P l In this course, we discussed the following: - Excavations/Trenching: Subpart P » 1926. 650 - Scope, application, and definitions applicable to this subpart » 1926. 651 - Specific excavation requirements » 1926. 652 - Requirements for protective systems This presentation was created by the N. C. Department of Labor for safety and health training.

Thank You For Attending! Final Questions? This presentation was created by the N. C. Department of Labor for safety and health training.