excavation safety€“ trench and excavation access – spoils piles – shoring and sloping •...

$: Excavation Safety€“ Trench and excavation access – Spoils piles – Shoring and sloping • Learn how to identify and mitigate excavation hazards Course Objectives\爀唀瀀漀渀$
Introduction

Excavation Safety • Welcome! This module will cover:

– The Federal OSHA excavation standard – CFR 1926 Subpart P, Excavations

• Course length: 30-40 minutes • Refer to your local state laws for more information.

Presenter

Presentation Notes

Welcome to this training module titled excavation safety. This module will help you understand the Federal OSHA excavation standard found in 29 CFR 1926 Subpart P, Excavations. Expect to spend about 30-40 minutes to complete this session. For more specific and detailed information, please refer to your local state laws where applicable.

Introduction

Course Objectives • Upon completion of this course, you should be familiar

with the hazards of trenching and related OSHA safety standards, including those regarding: – Classification of soils – Air monitoring – Trench and excavation access – Spoils piles – Shoring and sloping

• Learn how to identify and mitigate excavation hazards

Presenter

Presentation Notes

Course Objectives Upon completion of this course, you should be familiar with the hazards of trenching and related OSHA safety standards, including those regarding: classification of soils, air monitoring, safe access, spoils piles, shoring and sloping. It is critical that you take the time to fully understand the hazards associated with excavations and the different types of equipment and materials available to help protect yourself from becoming a victim of a trench collapse or cave-in.

Introduction

Learning Objectives • Upon completion of this training session, the

student will be able to: – 1: Identify major excavation hazards – 2: Describe types of excavation hazards – 3: Protect him/herself from excavation hazards – 4: Recognize employer requirements to protect

workers from excavation hazards

Presenter

Presentation Notes

Our overall learning objective for this course is for the student to gain sufficient knowledge in how to protect themselves from excavation hazards. Specifically, upon successful completion of this training session, the student will be able to: 1: Identify major excavation hazards 2: Describe types of excavation hazards 3: Protect him/herself from excavation hazards 4: Recognize employer requirements to protect workers from excavation hazards

Introduction

TIP: Disclaimer: This Compliance Assistance product is not a standard or regulation, and it creates no new legal obligations. The Compliance Assistance product is advisory in nature, informational in content, and is intended to assist employers in providing a safe and healthful workplace. Pursuant to the Occupational Safety and Health Act, employers must comply with safety and health standards promulgated by OSHA or by a State with an OSHA-approved State Plan. In addition, pursuant to Section 5(a)(1), the General Duty Clause of the Act, employers must provide their employees with a workplace free from recognized hazards likely to cause death or serious physical harm. Employers can be cited for violating the General Duty Clause if there is a recognized hazard and they do not take reasonable steps to prevent or to abate the hazard. However, failure to implement these recommendations is not, in itself, a violation of the General Duty Clause. Citations can only be based on standards, regulations, and the General Duty Clause.

Introduction

Topic 1 Overview • What is a excavation Hazard?

– Definitions – Statistics – Examples

• ALL excavation related deaths are 100% PREVENTABLE!

Presenter

Presentation Notes

Our first learning objective will focus on explaining the basic definitions of what an excavation hazard is. We will provide statistical data that helps you realize just how dangerous working in excavations can be and give you real life stories of serious injuries and deaths that have, and continue to occur, in the construction industry, from excavation cave-ins. With zero doubt, each and every excavation related death is 100% preventable… Educating you on how to identify and protect yourself from excavation hazards is our goal.

Introduction

Topic 2 Overview • What are the Major Types of excavation Hazards

in Construction? A. Unprotected edges B. Fall hazards C. Improper sloping or benching D. Spoils mismanagement E. Not properly classifying soils F. Improper shoring systems

Presenter

Presentation Notes

Our second topic of discussion will be focused on how to identify the major types of excavation Hazards in Construction. Numerous excavation hazards can be found in and around almost every construction project. Typical excavation hazards we will discuss include unprotected edges, fall hazards, improper sloping or benching, spoils mismanagement, not properly classifying soils, improper shoring systems, and the role of a competent person and their evaluations. We will discuss each of these typical hazards as well as examples of how to prevent exposure to them.

Introduction

Topic 3 Overview • How can I protect myself from excavation

Hazards? A. Minimum Training Requirements B. Safety Requirements for excavations C. Shoring systems D. Benching and Sloping E. Evaluating soils

Presenter

Presentation Notes

Topic number 3 is focused on providing critical information on, and examples of, how you can protect yourself from excavation hazards. We will discuss. Minimum training requirements Safety requirements for evaluating excavations Types of shoring systems The use of benching and Shoring Evaluating soils

Introduction

Topic 4 Overview • What is my employer required to do to protect

workers from excavations? • Provide excavation Protection Training & Equipment • Proper Excavation Techniques • Excavation Inspections and Use • Competent Person

Presenter

Presentation Notes

Finally, topic 4 will discuss your employer’s requirements to provide adequate protection of their workforce from excavation hazards. Some of the areas covered in this topic will include; Provide excavation Protection Training & Equipment Proper Excavation Techniques Excavation Inspections and Use Competent Person

Introduction

OSHA’s Excavation Safety Standards

• In place since 1989 • 37% of all trenching incidents occur at depths

less than 5 feet! • Most fatalities occur in trenches 5-15 feet deep • Employers & Employees are responsible to

ensure excavations are safe before entering • Safety Standards are designed to save your life!

Presenter

Presentation Notes

Excavation safety standards have been around for a long time. OSHA’s current rule took effect in 1989 and regulations adopted by states throughout the US are consistent with the federal standards. Compliance with the law is important, but more important is the fact that compliance also means the difference between life and death in a trench or excavation. Did you know that 37% of all trenching incidents occur at depths less than 5 feet! Or that more fatalities occur in trenches between 5 and 15 feet where employees have the most discretion and least oversight of their work? It is the responsibility of your employer and you to ensure that each and every excavation and trench has been evaluated for safety before anyone is allowed to enter. Protecting against cave-ins requires that you understand and follow the requirements for working safely in and around excavations. Your life may depend on it!

Introduction

Trench or Excavation? • Trench: a cut in the earth that is deeper and longer

than it is wide, but not wider than 15 feet • Excavation: any man-made cut, cavity, trench, or

depression in an earth surface, formed by earth removal

• Trenches and Excavations: – Similar characteristics – Equally dangerous – Require worker protection

Presenter

Presentation Notes

The definition of a trench is any cut in the earth which is deeper and longer than it is wide, but never wider than 15 feet. The accepted definition of an excavation is any cavity formed in the earth’s surface by cutting, digging or removing the earth. While characteristics may be similar, the dangers in each are equal and must be addressed to protect workers in trenches or excavations.

What is an Excavation Hazard?

Review the Facts: Excavation Fatality #1 • Victim: 37-year-old laborer, 3 years of experience • Task: installing a small diameter pipe in a trench • Trench:

– 3 feet wide, 12 – 15 feet deep, 90 feet long – Not shored or sloped – No box or shield – Evidence of a previous cave-in

• Results: Victim killed in a second cave-in • How was this preventable?

Presenter

Presentation Notes

A laborer, aged 37, with 3 years of experience in trenching and excavation was installing a small diameter pipe in a trench 3 feet wide, 12-15 feet deep and 90 feet long. The trench was not shored or sloped nor was there a box or shield to protect the employee. There was also evidence of a previous cave-in. The employee apparently re-entered the trench and a second cave-in occurred, burying him. He was found face down in the bottom of the trench. How could this tragedy have been prevented? After taking this course you will have the information necessary to prevent from becoming victim of a cave-in. Click to the next slide to see what the OSHA investigation determined.


Excavation Fatality Root Cause • OSHA citations to management included failure to

provide: – Sloping or shoring – Adequate PPE – Ladder, ramp, or runway access – Proper training

• This death was 100% Preventable!

Presenter

Presentation Notes

The violations cited by OSHA included failure to provide sloping or shoring, failure to provide adequate personal protective equipment, failure to provide a ladder, ramp or runway for employees in the trench and failure to provide training on hazards of excavations to employees. This death was preventable and the exposure should have been obvious to the employee and the employer.


Review the Facts: Excavation Fatality 2 • Victims/task: employees replacing a concrete filter

tank at a carwash • Trench:

• 9 feet deep, 14 feet long, 6 feet wide • No shoring or sloping provided

• Tragedy: a vertical face gave way, killing one employee, seriously injuring the other.

Presenter

Presentation Notes

Employees were replacing a concrete filter tank at a carwash. Once the smaller tank was removed, two employees entered the 9 foot deep trench to level the bottom. Suddenly, one of the vertical faces of the unprotected trench gave way burying and killing one employee and seriously injuring the other employee. The fact that no shoring or sloping were provided led to this tragic incident. Click to the next slide to see what the OSHA investigation determined.


Excavation Fatality 2 (cont.) • OSHA citations to management included failure to:

– Shore unstable soils. – Train employees. – Provide PPE. – Enforce the use of PPE. – Protect against impalement.

Presenter

Presentation Notes

The OSHA investigation determined that citations were to be issued to the company for failure to follow the minimum excavation requirements as follows: Failure to shore the unstable sides of the trench Failure to train employees Failure to provide for and enforce wearing of personal protective equipment, and Failure to protect against the hazards of impalement . While the intent of issuing citations is to influence management to ensure all rules But none of the citations will return a man from his grave or repair the injury to a second. Excavation is hazardous, but you can protect yourself if you understand the hazards and methods of protecting yourself and others.

15

Find and Fix Recognize Any Hazard(s)?

Presenter

Presentation Notes

Take a look at this picture and see if you can identify any hazards that exist in this photo? Roll your cursor over the photo to find each of the two hazards.

16

Find and Fix

Presenter

Presentation Notes

[No VO. Use the following as text displays when the hotspot is activated.] There is a fall hazard around the perimeter of the trench that requires a warning system to keep people a safe distance away and workers exposed to a fall hazard greater than 6 feet must be trained in and effectively wearing fall protection equipment. The worker is about 6 feet tall, so you can tell in the photo that the trench is over 10 feet deep. The good news is that they are using a trench box, the bad news is that they have not provided a safe way to enter or exit the trench box. Employees must be protected at all times, including while entering and exiting the trench box.


Myths of Excavation • “If the trench is not deeper than 5 feet, I don’t have

to shore or protect the excavation.” • “Air monitoring is only for confined spaces, not

excavations.” • “I can dig myself out if I am buried.” • “Hitting utilities is simply part of the business!” • “If the soil looks pretty good, it must be type A.”

Presenter

Presentation Notes

The list in front of you is a list of some of the myths of excavation. Myths, stories, scuttlebutt, whatever you call it, are all based on some information but are often not factual and could be both misleading and potentially deadly. Let’s debunk, that is take on and prove untrue, each of the myths before we go further in your training.


Myth 1: Under Five feet, Shoring Is Not Required • The OSHA regulation actually says:

– Each employee shall be protected . . . Except when excavations are less than 5 feet and examination of the ground by a competent person provides no indication of a potential cave-in.

• Therefore, based on the competent person’s examination, shoring may still be required.

Presenter

Presentation Notes

As with all myths, there is a basis in truth. The regulation says that employees who enter trenches must be protected with an adequate protective system except when the “excavations are less than 5 feet in depth” Most employers and many employees stop reading then. That’s how myths start and are perpetuated. The rest of the sentence says “and examination of the ground by a competent person provides no indication of a potential cave-in”. A competent person who knows the hazards of excavation, understands soils and has the authority to fix problems identified must inspect the trench and provide protection if the soil is unstable. Say good bye to myth number 1.


Myth 2: Air Monitoring Is Not Required in Trenches • OSHA requires air monitoring in confined spaces.

– Includes trenches deeper than 4 feet, which present hazards such as: • Methane gas (landfills) • Flammable vapors (old gas stations) • Carbon monoxide (your own equipment) • Various chemicals (welding tasks, etc.)

Safety Tip: Most of us don’t think of trenches as confined spaces, so the thought of air monitoring is not a primary issue when excavating.

Presenter

Presentation Notes

If you look at the OSHA regulations for confined spaces you will see that air monitoring is required before entering confined spaces. The myth that air monitoring is not required in trenches needs to be addressed. If you excavate in or around old landfill areas you will usually find methane gas, a highly flammable colorless and ordorless gas. If you dig near an old gas station site, waste gasoline or diesel that seeped into the ground, can when exposed, release flammable vapors. Your own heavy equipment and street traffic can release carbon monoxide, and any chemicals you introduce into the trench such as glues or solvents or any activity such as pipe cutting, welding or similar work can introduce hazards that can only be detected through air monitoring. And in fact when your trench is deeper than 4 feet and hazards may be present, air monitoring must be done before entry.


Myth 3: I Can Dig Myself Out • Reality of a cave-in:

– A cubic yard of soil can weigh as much as a small pickup truck.

– Soil pressing on the chest can make it impossible to breathe.

– Fine particles of dirt can clog your nose, mouth, and lungs.

Safety Tip: The first order of business is protecting workers in the trench, not planning on an impossible self rescue.

Presenter

Presentation Notes

A cubic yard of soil, a mass 3 feet by 3 feet by 3 feet, can weigh as much as a small pickup truck. Soil pressing on the chest will not allow the diaphragm of your chest to expand and allow air into the lungs. Fine particles of dirt can clog your nose, mouth and lungs making it impossible to do anything, including digging yourself out.


Myth 4: Hitting Utilities Is Part of the Business • Live electrical lines in the ground can kill workers and

cause significant property damage. – A gas line hit can lead to an explosion. – A broken water line can fill a trench in seconds. – Contact with buried power cables can kill.

Safety Tip: Always your local utility locating service such as 811 before you dig, and get the utilities marked. Hand dig to locate the lines safely.

Presenter

Presentation Notes

Oldtimers might tell you stories about backhoes being the best utility locators around. Those who are still around to tell stories like this are the lucky ones. A natural gas line strike can explode, violently killing workers and damaging property. A broken high pressure water line can fill a trench in seconds, leaving a worker no time to escape. Live electrical lines in the ground have killed workers in trenches, equipment operators above, and have caused significant property damage. Always call your local utility locator service such as 811, call before you dig, and get the utilities marked. Hand dig to locate the lines safely. Hitting utilities must never be part of the business.


Myth 5: If the Soil Looks Good, It Must Be Type A • To be classified as Type A, the soil can NOT be:

– Previously disturbed – Cracked or fissured – Subject to vibration – Seeping water – Part of a mixed layered system

• To be classified as Type A, the soil MUST be: – Fully tested by a competent person, every time

Safety Tip: Type A soil is the best soil to be digging in. However, most soils that you will encounter will not be type A.

Presenter

Presentation Notes

Type A soil is cohesive and strong and because of this strength it provides many different options for protecting workers. But soil cannot be classified as type A if it has been previously disturbed, it is cracked or fissured, it is subject to vibration, it is seeping water or it is part of a sloped layered system of different soils. Much of our excavation is done in cities where soils have been dug and back filled numerous times. The competent person must do one visual and one manual test to determine soil type, every time. Type A is hard to find and assuming your soil is type A gets everybody in trouble. Avoid this myth at all costs.

Types of Excavation Hazards

The Competent Person • Capable of identifying existing and predictable hazards • Authorized to take prompt corrective measures • Specifically trained in:

– Soils analysis – Protective systems & equipment – OSHA standard requirements

Safety Tip: Learn more about the definition and role of the competent person in the attached safety link.

http://www.osha.gov/SLTC/etools/construction/trenching/competent_person.html

Presenter

Presentation Notes

Federal regulations require that certain excavation activities be designed, inspected or supervised by a competent person. The OSHA Construction Standard defines a competent person as someone who is capable of identifying existing and predictable hazards in the surroundings, or working conditions which are unsanitary, hazardous, or dangerous to employees, and who has authorization to take prompt corrective measures to eliminate them. In order to be a “competent person” in excavations, you must have had specific training in, and be knowledgeable about soils analysis, the use and design of protective systems and the OSHA requirements of the applicable standards. One who does not have such training or knowledge cannot possibly be capable of identifying existing and predictable hazards in excavation work or in taking prompt corrective measures.


What causes Cave-ins? • Characteristics of soil:

– Lateral pressure up to 800 pounds per square foot – Cubic yard can weigh 3000 pounds – Cave-ins happened quickly with little warning – Self-rescue nearly impossible due to the weight

Safety Tip: Don’t be fooled thinking that you will be in a trench for only a few minutes. Never enter an unprotected trench or excavation.

Presenter

Presentation Notes

The classification of soils is ultimately the most critical step in determining the safe plan of action for working in and around excavations. Before we discuss soil types, we should discuss the forces that cause excavation failures. So how do cave-ins happen? The answer is in soil types and lateral soil pressures. There are inherent pressures that exist in the ground at all times. Our main focus will be on what is commonly called lateral soil pressure. Lateral soil pressure is the naturally occurring force that exists in the ground that makes the sides of an excavation want to move, which leads to cave-ins. This lateral cave-in pressure can be as much as 800 pounds per square foot in non-cohesive or saturated soils. For example, a cubic yard of soil, which is just a 3 foot square cube of soil, can weigh between 2700 and 3200 pounds, or as much as a pickup truck. The shear weight alone of the quickly moving soil that occurs during a cave-in makes self rescue almost impossible… unless you can lift 3,000 pounds!


Soil Failures • Stress cracking near the edge of the excavation

– Caused by Soil Pressures or Equipment Vibrations – Indicative of Impending Failure – Competent Person required to

• Remove workers • Specify appropriate protective systems • Inspect daily for effectiveness

Safety Tip: Workers seeing problems should exit the trench and report these hazards to their supervisor or the competent person.

Presenter

Presentation Notes

Excavation cave-ins can be caused by numerous reasons, but the most common are caused by stress cracking in the surrounding soil. Stress cracks can result from excessive soil pressures that can be naturally occurring or from external forces like the nearby operation of heavy equipment. The graphic on your screen shows some typical failure modes that lead to cave-ins. It is the role of the competent person to evaluate and recognize any of these hazards, and take appropriate actions to protect workers, before a catastrophic failure occurs. Excavations with known hazards must be inspected daily to ensure protective systems are adequate and effective.


Spoil Piles • Spoils too close to the edge of the trench can:

– Slide in, on top of employees. – Put lateral pressure on side walls, causing failure.

• Piles must be kept at least 2 feet from the edge. – Essential for preventing a cave-in

• Water saturation increases the risk of cave-ins Safety Tip: Clay soils saturated with water may fail in the case where a large soil section sheers off from the side wall and rolls to the opposite wall. An employee standing at the point opposite the failure could be trapped and pinned by the soil. A second failure of the wall above could bury him.

Presenter

Presentation Notes

When excavating occurs, the soil removed is commonly called the spoils. The minimum requirement for storing spoils piles is that they must be kept a minimum of 2 feet away from the edge of the excavation or trench. Proper spoils storage is an essential step in preventing a cave-in incident. Spoils that are stored too close to the edge of the trench can slide in on top of employees and the weight of the spoil can put lateral pressure on the side walls of any excavation, leading to a cave-in. Clay soils saturated with water may fail in the manner shown in the slide where a large soil section may sheer off from the side wall and roll into the opposite wall. An employee standing at the point opposite the failure could be trapped and pinned by the soil. A second failure of the wall above could bury him.

Situational Analysis

• You are in an excavation and see a bulge beginning between shores. The excavation is equipped with aluminum hydraulic shoring protection. What is your immediate reaction? – Leave the trench and remove any other employees

immediately. <ans> Correct! Even with aluminum hydraulic shoring protection, your immediate reaction should be to leave the trench. Report the problem to the competent person for correction.

– Keep working and report the problem to the competent person at your first opportunity. <ans> Incorrect; even with shoring protection, your immediate reaction should be to leave the trench. Report the problem to the competent person for correction before continuing work.

Presenter

Presentation Notes

Now let’s try a practical exercise or Situational Analysis. You are in an excavation and see a bulge beginning between shores. The excavation is equipped with aluminum hydraulic shoring protection. What is your immediate reaction? Leave the trench and remove any other employees immediately. <ans> Correct! Even with aluminum hydraulic shoring protection, your immediate reaction should be to leave the trench. Report the problem to the competent person for correction. Report the problem to the competent person at the time of the next inspection. <ans> Incorrect; even with shoring protection, your immediate reaction should be to leave the trench. Report the problem to the competent person for correction before continuing work.

Soil and Soil Classification

Soil Types • Four Classes of Soils • OSHA assigns the following 4 classifications of soil:

– Solid rock – Type A – Type B – Type C

Presenter

Presentation Notes

OSHA has identified 4 basic categories for the classifications of soils that are to be used for determining the type of soil in an excavation and the protective systems that are best designed to protect the personnel that must enter the excavations. The four soil type classifications are: Solid rock Type A soils Type B soils and Type C soils


Soil Types • Solid Rock

– Natural solid mineral material – Can be excavated with vertical sides – Will remain intact while exposed – Identification often requires the help of a geologist

• If unsure, take the time to ask for a second opinion, lives may depend on it!

Presenter

Presentation Notes

Solid rock is a natural solid mineral material that can be excavated with vertical sides that will remain intact when left exposed and unsupported. Solid rock identification often requires the help of a geologist or geotechnical specialist due to the different types and characteristics of rock. Some solid mineral materials, which might appear to a competent person as solid rock, will display characteristics of failure that makes an unprotected trench a potential death trap. A true competent person will know if they come across a material that they have no experience with and will ask for a second opinion. Taking the time to ask for a second opinion may save your life or the life of your co-workers.


Safety Tip: Some solid mineral materials which might appear to an excavator as solid rock display characteristics of failure that makes an unprotected trench a potential death trap.

Safety Tip: Check out the OSHA letter on Miami Oolite rock at: http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=21764

Presenter

Presentation Notes

Solid rock is a natural solid mineral material that can be excavated with vertical sides that will remain intact when left exposed and unsupported. Solid rock identification often requires the help of a geologist or geotechnical specialist due to the different types and characteristics of rock. Some solid mineral materials, which might appear to a competent person as solid rock, will display characteristics of failure that makes an unprotected trench a potential death trap. A true competent person will know if they come across a material that they have no experience with and will ask for a second opinion. Taking the time to ask for a second opinion may save your life or the life of your co-workers.


Type A Soils • Type A Soils include:

– Various clays: silty clay, sandy clay, clay loam and others – Cemented soils: caliche and hardpan

• No soil is Type A if: – The soil is fissured – The soil is subject to vibration – The soil has been previously disturbed – Other factors exist that would classify it as a less

stable material

Presenter

Presentation Notes

Type A soils are often made up of various clays such as silty clay, sandy clay, clay loam and, in some cases, silty clay loam and sandy clay loam. Cemented soils such as caliche and hardpan are also considered Type A. Caliche is a sedimentary rock of hardened calcium carbonate that cements together other materials, including gravel, sand, clay, and silt. Always remember that no soil is Type A if: The soil is fissured; or The soil is subject to vibration from heavy traffic, pile driving, or similar effects; or The soil has been previously disturbed; or The material is subject to other factors that would require it to be classified as a less stable material.


Safety Tip: Caliche is a sedimentary rock, a hardened deposit of calcium carbonate. This calcium carbonate cements together other materials, including gravel, sand, clay, and silt. Caliche occurs worldwide, generally in arid or semi-arid regions, including the High Plains of the western USA, and in the Sonoran Desert.


Type B Soils

• Type B Soils include most granular soils that include: – Angular gravel, silt, silt loam, sandy loam and, in

some cases, silty clay loam and sandy clay loam. – Previously disturbed soils, except those which

would otherwise be classified as type C – Soil that would meet the requirements for type A,

but is in some way unstable

Presenter

Presentation Notes

Type B soils are a general classification of soils that includes most granular soils, including angular gravel, which is very similar to crushed rock, silt, silt loam, sandy loam and, in some cases, silty clay loam and sandy clay loam. Type B soils also include previously disturbed soils except those which would otherwise be classified as Type C soil. Type B soils can also meet the requirements for Type A soil, but have evidence of fissuring, are subject to vibration, or is dry, unstable rock.


Type C Soils • Type C

– Typically granular – Gravel, sand, and loamy sand – Submerged soil – Soil from which water is freely seeping – Submerged rock that is not stable

• High potential for instability and cave-ins

Presenter

Presentation Notes

Type C soil typically is an unstable, granular soil which includes gravel, sand, and loamy sand. It can also be submerged soil or soil from which water is freely seeping, as well as submerged rock that is not stable. Excavations in Type C soil will have a high potential for instability and cave-ins.


Classifying Soils Required Soil Tests • One visual and one manual test, by a competent

person, on fresh soil unaffected by weather • Common tests

– Ribbon – Thread – Thumb – Dry strength – Sedimentation

Presenter

Presentation Notes

OSHA requires that the competent person perform one visual and one manual test on a soil sample fresh out of the ground and not impacted by weather conditions at the site. Some common examples of tests conducted by competent persons on soils include ribbon tests, thread tests, thumb penetration, dry strength and sedimentation. The ribbon test is the most common method used in the field for evaluating soils.


Classifying Soils Critical to be “Correct” • No matter what type of process the competent

person uses: – Soil must be classified before a protective system

decision can be made. – Results must be correct; lives will depend upon it.

Safety Tip: For more information and training, refer to other details on soil classification and analysis.

Presenter

Presentation Notes

No matter what type of process the competent person uses from the simple hand testing methods to the more sophisticated tools of the trade, the soil must be classified before a protective system decision can be made. Identify the soil incorrectly and install protective equipment based on that erroneous decision, and the lives of the men and women in the trench could be in danger.

Protection from Excavation Hazards

Learning Objective # 2: Protective Systems Protecting Yourself from Harm: • Employees in a trench or excavation must be

protected by a protective system. • Only two exceptions:

– Entirely stable rock – Less than 5 feet without sign of potential cave-in

Safety Tip: Protective System means a method of protecting employees from cave-ins, from material that could fall or roll from an excavation face or into an excavation, or from the collapse of adjacent structures. Protective systems include support systems, sloping and benching systems, shield systems, and other systems that provide the necessary protection.

Presenter

Presentation Notes

Now that we have discussed some of the different types of hazards that can exist in an excavation, we will begin the review of Learning Objective #2, how to protect ourselves from excavation hazards. In this next section we will discuss the different systems and processes available that are designed specifically to will help you protect yourself from excavation hazards. The laws the require employers to protect employees from harm in the workplace are very clear, but over a thousand construction workers still die every year on the jobsite. Taking the time to understand the rules and regulations that are designed to help protect you when at work, will pay dividends at the end of each work shift. For example, did you know that when anyone needs to enter any trench or excavation, their lives must be protected by installing protective systems in the trench that will protect them in case of a cave-in? That is the law! The only exceptions to this rule are if the trench is made entirely from solid rock, which is very rare, or, the trench is less than 5 feet in depth and there are no indications of potential cave-ins.


Types of Protective Systems • Sloping • Benching • Wood shoring • Aluminum hydraulic shoring • Waler systems • Trench boxes • Screw jacks • Engineered systems

Safety Tip: Information on protective systems can be found in the OSHA standards at Subpart P of 1926 the Construction Safety Standards

Presenter

Presentation Notes

When an excavation is 5 feet or deeper, protective systems MUST be used. No Exceptions unless the trench is in solid rock. 99.9% of all trenches are not in solid rock so we must protect our employees who have to enter these type of excavations, no question. The competent person has many solutions available to them today that will protect employees from potential cave-ins and examples of those systems are: sloping, benching, wood shoring, aluminum hydraulic shoring, waler systems, trench boxes, screw jacks, and engineered systems. Each of these systems are specifically designed to provide a safety barrier for the workers inside a trench or excavation.


Sloping and Benching • The requirements of sloping and benching are

detailed in link. Click on the link and review: – Important information – Charts and diagrams

• Shoring and sloping are a preferred method for creating a safe excavation.

Safety Tip: Visit http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10932.

Presenter

Presentation Notes

Let’s take a look at appendix B to subpart P. Click on the link to go to the appendix and spend a little time to become familiar with the appendix. There is plenty of important information in this appendix that you should be acquainted with. Scroll down through the appendix paying special attention to the charts and diagrams. Shoring and sloping are a preferred method for creating a safe excavation to work in and around. We will discuss some of the requirements in the next few screens.


Find the Excavation Hazards! • Identify hazards

Presenter

Presentation Notes

Take a look at this photo. It’s not a perfect picture. Can you identify any safety hazards in the photo? Roll your cursor over the photo for help in finding 4 hazards. Notes for photo. Ladder does not extend to bottom of trench. A-frame ladders are being used as straight ladders. Dewatering indicates water and soil stability issues. Different soils that react differently as in native soils and bedding materials.


Protective Systems Sloping – Type A • Type A soils

– Strongest and most cohesive – The most sloping and benching options – Simple slope of ¾ to 1: every 1 foot down, soil

must be excavated ¾ of a foot out from the toe

Safety Tip: The slope of an excavation is measured from the toe of the slope to the top edge. The toe is where the slope meets the bottom.

Presenter

Presentation Notes

Because Type A soils are the strongest and most cohesive of soils, there are more choices of sloping and benching options than in any other soil. First choice is a simple slope of ¾ to 1, that is to say for every 1 foot down you go the soil must be excavated ¾ of a foot out from the toe. This equates to an angle of 53 degrees. For example, in a trench that was 8 feet deep and 3 feet wide at the bottom, a proper slope in type A soil measured from edge to edge would be 15 feet across.


Protective Systems Sloping & Benching – Type B Soils • Type B soils

– Most common soil encountered – Four options for protecting workers – In a simple slope, 45-degree angle of repose – Rise and run of each bench will be equal

Presenter

Presentation Notes

Type B Soil is the most common type of soil encountered when excavating. In Type B soil the slope allowed is a 1:1 slope. That means for every I foot in depth, the trench width must also increase by 1 foot, resulting in a angle of 45 degrees. If benching is chosen as the method of protection in the trench, the angle formed by the benches must also retain that 45 degree slope. Thus the rise and run of each bench will be equal and in an 8 foot deep trench each bench would have a rise of 4 feet and a run of 4 feet.


Protective Systems Sloping – Type C • Type C soils

– Poorest quality – Sloping is still possible – Angle of repose is very low (34 degrees)

Safety Tip: In type C soil, for every foot down, the slope must extend 1.5 feet from the toe.

Presenter

Presentation Notes

While it is not very common, it is possible for an excavator to slope in type C soil, but it is often impractical due to the total overall size of the final excavation. For instance, sloping in Type C soil requires a 1:1.5 ratio of slope, which equates to a very low 34 degree angle. That means for every foot in depth, the slope must extend 1.5 feet from the toe. As you can tell in the diagram, the size of the overall excavation can become very large, requiring the removal of large quantities of soil.


Protective Systems Aluminum Hydraulic Shoring • Light weight aluminum frames

– Patents first issued in Late 60’s and early 70’s – Sliding cylinders, hydraulic fluids – May be installed and removed by one person – Entering the trench not required

Presenter

Presentation Notes

Aluminum hydraulic shoring has been around since the early 1970’s when they were used with light weight aluminum frames and sliding cylinders to secure them against the side walls of trenches. The units were designed so that one individual could install and remove the shores and could do the installation and removal without entering the trench. The elimination of exposure to employees installing shoring systems was an incredible benefit in the underground industry. The photo you see in this slide is of a standard 6 foot shore with two sliding cylinders of 2” diameter. This is a very common tool used today as a protective system in excavations. Adjacent to the shore is a standard pump used to move the cylinders and press the side rails against the side walls of the excavation.


Protective Systems Aluminum Hydraulic Shoring • Aluminum hydraulic shores: vertical, bearing fully on

the side vertical walls of the trench. • Cylinders: maximum spacing of 4 feet vertically,

bottom cylinder no more than 4 feet up. • Side rails: must extend to within 2 feet of the bottom

to prevent kickout. Safety Tip: Well, first, there should be a solid pad under the outrigger plate to spread the load. Secondly, the influence of the crane loading on the trench must be considered when setting up the crane.

Presenter

Presentation Notes

When installing aluminum hydraulic shores the shores should be vertical and bear fully on the side vertical walls of the trench. Cylinders can have a maximum spacing of 4 feet vertically and the bottom cylinder can be no more than 4 feet from the bottom of the trench. The side rails of the shores must extend to within 2 feet of the bottom of the trench. The 2 foot distance requirement from the bottom of the trench is to prevent kickout of soils behind the shore. Kickout happens when soils at the bottom of the trench fail causing loss of support along the entire vertical matrix of the soil behind the shore.


Protective Systems Aluminum Hydraulic Shoring • Shores pumped to a minimum of 750 pounds of

pressure (1000 pounds is best practice) • 1000 pounds of pressure translates to 3000 psi

against side rails and into the soil

Presenter

Presentation Notes

Manufacturers require that most shores be pumped up to a minimum of 750 pounds of pressure. However, the common practice is to increase that amount to 1000 pounds of pressure to ensure enough counter pressure is applied to prevent a wall collapse. Through the magic of hydraulics, that 1000 pounds of pressure translates to 3000 pounds per square inch of pressure against the side rails of the shores and in turn into the soil.


Protective Systems Waler Systems (cont.) • Type C soil:

– Walers must be used. – Typically requires timber backing;

• Street plates or sheet pile can also be used

Safety Tip: Follow OSHA tables covering the use of waler systems in types B and C soil.

Presenter

Presentation Notes

Vertical aluminum hydraulic shores can be used for types A & B soil. But in type C soil, walers such as you see in this illustration must be used in order to protect employees working in a Type C soil trench. Typically, as shown in the illustration, wales used in type C soil require timber backing to hold the soil in place but street plates, soldier piles or sheet piles can also be used as backing. A competent person must be involved in the design and placement of these systems.


Protective Systems • Many systems for protecting workers (Appendix E)

– Trench boxes – Trench shields – Slide rail systems – Sheet pile – Screw jack systems

Safety Tip: All systems have one item in common and that is a set of manufacturer’s tabulated data to be used for proper design and installation of the equipment.

Presenter

Presentation Notes

Other protective systems are available and used throughout the construction industry. Commonly used protective systems include trench boxes, trench shields, slide rail systems, sheet pile and screw jack systems. All systems have one item in common and that is a set of manufacturer’s tabulated data that is used for ensuring proper design and installation of the equipment. Trench boxes and shields are very common today and are used in large excavations and pipeline installations. For a list of other common protective systems, we have added a link to appendix E of the OSHA regulations.


Trench Boxes • Trench shields or boxes:

– Protect against collapsing soil – Do not prevent cave-ins – Available in a variety of dimensions – Usually aluminum or steel – May be custom-built from tabulated data – Installed such that hazardous movement of the shield is

restricted in sudden lateral pressures

Safety Tip: Workers must not be allowed in shields when shields are being installed, removed, or moved vertically.

Presenter

Presentation Notes

Trench shields or boxes provide employees a safe work area by protecting them from collapsing soil. Shields don’t prevent cave-ins but “shield” workers if a face does collapse. They are usually placed in the excavation by heavy equipment. Shoring and shielding systems are available from manufacturers in a variety of dimensions, usually aluminum or steel, or they can be custom-built from tabulated data approved by a registered professional engineer. Manufacturers will also provide tabulated data with their systems that includes engineering specifications, depth ratings, special instructions, and system limitations. Only by carefully studying and understanding the manufacturer’s tabulated data can the competent person choose the correct protective system. Shields shall be installed in a way that will restrict lateral or other hazardous movement of the shield in the event of sudden lateral pressures.


Screw Jacks • Screw jack systems:

– Struts adjusted manually – Worker must be in the trench for adjustment – No uniform preloading – Weight creates handling difficulties

Presenter

Presentation Notes

Screw jack systems differ from hydraulic and pneumatic systems in that the struts of a screw jack system must be adjusted manually. This creates a hazard because the worker is required to be in the trench in order to adjust the strut. In addition, uniform "preloading" cannot be achieved with screw jacks, and their weight creates handling difficulties.

Excavations Deeper than 20 feet • Engineered Design

– Requires a Registered Professional Engineer – Allows deviations from OSHA standard – Allows greater flexibility in use – Required whenever using shores in a manner that differs

from OSHA requirements

Safety Tip: Tabulated Data means tables and charts approved by a registered professional engineer and used to design and construct a protective system.


Presenter

Presentation Notes

The OSHA Standard mandates that a registered professional engineer be involved in shoring designs deeper than 20 feet. Manufacturer’s tabulated data allows the use of identified shores to a depth of 25 feet. Such use is allowable because these systems are engineered. If data to support decisions are not available users must revert to the OSHA standard requirements. There is definite value to meeting the requirement of having tabulated data on site at all times.


Engineered Systems • Registered professional engineer: person who is

registered as a professional engineer in the state in which the work is to be performed;

• However, any state is acceptable within the meaning of this standard when approving designs for manufactured protective systems or tabulated data to be used in interstate commerce.

Presenter

Presentation Notes

Here’s an example of an engineered system. These should be designed by a registered professional engineer. Registered Professional Engineer means a person who is registered as a professional engineer in the state where the work is to be performed. However, a professional engineer, registered in any state is deemed to be a “registered professional engineer” within the meaning of this standard when approving designs for “manufactured protective systems” or “tabulated data” to be used in interstate commerce.

New Employer Requirements

Employers Must Provide Protection • Protection for employees entering trenches or

excavations is required at all times. – Employers Responsibility to provide you training,

safe work procedures and the right tools to get the job done safely

– Its YOUR responsibility to follow procedures and NEVER put your life at risk on the job!

Presenter

Presentation Notes

OSHA requires your employer to provide a safe and healthful working environment. Every employer is required to properly train their employees and to provide safe work procedures and the proper tools so that you can safely perform your work. You have the right to notify OSHA if you ever feel your safety is being compromised at work. While protecting employees that enter trenches or excavations is required at all times, the final responsibility lies with the employee to make the right decision and not place their lives at risk. If it is unsafe to enter, it is your final decision not to enter. No job is worth your life! In addition, it is YOUR responsibility to follow safety procedures and not take unnecessary risks!

Employer Requirements

Safe Planning of Work • Proper planning and preparation required for

anything that could create a hazard within the Zone of Influence, such as: – Trees, spoil piles – Curbs, gutters, sidewalks – Buildings, foundations, utility poles – Excavating equipment, dump trucks – People

Presenter

Presentation Notes

Trenching and excavation work begins with planning. When any surface encumbrances and underground installations are identified they must be dealt with through proper planning and preparation. Surface encumbrances include trees, spoil piles, curbs, gutters, sidewalks, buildings and foundations, utility poles, excavating equipment, dump trucks and PEOPLE, or anything that could create a hazard to employees within the Zone of Influence around the trench or excavation.


Provide Location of Underground Installations • Underground utilities must be located and marked. • Contact utility companies and owners in advance. • After the allotted time, proceed with caution.

– Hand digging, potholing, equipment for detection

• Once cut is open, all underground installations must be protected, supported, or removed.

• Each company (subcontractors) must receive a permit from the one-call organization. Safety Tip: Be careful of overhead utility hazards as excavation equipment can strike power lines, and make sure that your equipment is at least 10 feet away from all above-ground power sources.

Presenter

Presentation Notes

Your employer is responsible to identify known hazards and to ensure you have the proper equipment and training to perform the work safely. Underground Utilities must be located and marked prior to excavating. Utility companies and owners must be contacted within established local response times, which are typically 2 working days. If the owner or utility company cannot respond within the allotted time, the excavation can proceed with caution and acceptable means such as hand digging or potholing. Alternatively, equipment must be provided for detection. Remember that once the cut is open, all underground installations must be protected, supported, or removed. Be careful of overhead utility hazards as excavation equipment can strike power lines, and make sure that your equipment is at least 10 feet away from all above-ground power sources. Each company who excavates on a job site must receive a permit to dig from the one-call organization in the area of the work. No longer is it acceptable for a subcontractor to work under the permit of the general contractor.


Provide Safe Access and Egress • Cuts over 4 feet deep: safe access and egress

required within 25 feet of lateral travel. • When using ladders:

– Must extend at least 3 feet over solid ground – Secure at 4 to 1 angle to prevent movement

Safety Tip: If you are not using a structural ramp then you must use a ladder or other safe means of entry and exit.

Presenter

Presentation Notes

Your employer is required to provide you a safe means of access and egress. Safe access must be supplied if the excavation is over four feet deep and must be located within 25 feet of lateral travel of the employee. When using a ladder as the means of access, it must extend at least three feet over solid ground and be secured at a 4 to 1 angle to prevent movement.


Protection from Vehicular Traffic • In the presence of vehicular traffic:

– Highly visible clothing with reflective material – Adequate signage, markings, and traffic control – Lights at night – Plan approved by local government

Presenter

Presentation Notes

If employees are exposed to vehicular traffic, they must wear highly visible clothing marked with reflective material, such as an orange or fluorescent green traffic vest with reflective tape. The excavation site must have adequate signage, markings, and traffic control to direct traffic around the workers and the trench. There must be lights at night and an adequate traffic control plan approved by the city, county or special district in which your are working.


Exposure to Falling Loads • To avoid being struck:

– No work under overhead loads being transported by lifting or digging equipment

– Employees must stand away from vehicles being loaded or unloaded

– Stand clear of loads being lowered into the trench

Employees should be wearing hardhats, safety glasses and high visibility vests to protect against obvious hazards.

Presenter

Presentation Notes

No one is ever allowed to work underneath or be exposed to overhead loads being transported by lifting or digging equipment. In addition, employees are required to stand away from any vehicle being loaded or unloaded to avoid being struck by any falling materials. Stand clear of loads being lowered into the trench. Do not stand in the trench while equipment is operating. Never allow a sticking control switch or an operators sneeze to be the reason you don’t go home that night! Stay 10 feet back from operating equipment at all times!


Warning Systems for Mobile Equipment • Equipment presents many hazards

– Falling into the trench – Unexpected equipment failures or movements

• Warning system required when there is not a clear view of the ditch: barricades, spotters with established hand signals, stop logs

Safety Tip: Workers must be aware of the working radius of equipment, make their presence known, establish eye contact with the operator, and maintain a safe distance.

Presenter

Presentation Notes

Working with equipment in an excavation presents many hazards for pedestrians and equipment operators. In addition, equipment falling into a trench and unexpected equipment failures or movements can have lethal results. Your employer is required to provide back alarms on any mobile equipment and install a warning system such as barricades, spotters with established hand signals, or stop logs, to keep anything from falling in or burying workers with material.


Evaluating for Hazardous Atmospheres • If you suspect a hazard, test the area with a direct-

reading calibrated instrument or gas monitor. • The atmosphere must be declared safe before

workers are allowed into the excavation. • See Confined Spaces Entry module for a more

detailed discussion of identifying, controlling, and testing confined spaces.

Safety Tip: Other courses in Hazardous Materials, Asbestos, and Confined Spaces that will discuss in depth potentially lethal environments, such as lack of oxygen, volatile combustibles or explosive fuels, poisons, and asbestos containing rock.

Presenter

Presentation Notes

Your employer is required to verify that safe levels of oxygen exist and that toxic chemicals or gases are not present in any excavation before you enter. If you or a Competent Person suspects a hazard in the excavation, test the area with a direct-reading calibrated instrument or gas monitor. The atmosphere must be declared safe, BEFORE workers are allowed into the excavation. Please refer to other training opportunities in Confined Spaces Entry for a more detailed discussion of identifying, controlling, and testing confined spaces.


Protection from Water Accumulation Hazards • Do not work in excavations where there are signs of

accumulating water. – May weaken the side walls

• Protection requirements may include: – Special support or shield systems – Water removal (monitored by competent person)

Safety Tip: Keep in mind that any water being discharged may be subject to your local storm water discharge regulations.

Presenter

Presentation Notes

Employees must not work in excavations where there are signs of accumulating water, as it may weaken the side walls of the trench. No work is allowed until workers are protected from the hazards of water accumulation. Protection requirements may include special support or shield systems to safeguard against cave-ins and water removal to control the level of accumulating water. If the water is drained or controlled by using water removal equipment, the equipment and procedures must be monitored by a competent person to ensure proper operation.


Stability of Adjacent Structures • Buildings, parallel utilities, utility poles, or sidewalks

commonly exist near the excavation. – Threat of failure when exposed or undercut – Should be underpinned or cribbed – Enlist a registered professional engineer

Presenter

Presentation Notes

The stability of adjacent structures is another concern in any excavation. Buildings, parallel utilities, utility poles, or sidewalks commonly exist nearby. The threat of these structures failing when exposed or under-cut is very high and therefore they should be underpinned or cribbed to transfer the loads and help support them. Usually, a registered professional engineer must determine that the structure poses no threat or that it is sufficiently protected.


Competent Person Inspections • Prior to work and as needed (e.g., after a change in

conditions), competent person must inspect the site – Existing or predictable hazards – Indications of impending failure of protective

systems (shoring, shielding, sloping) – Other potentially hazardous atmospheres

Safety Tip: Workers and the job supervisor should also be trained to recognize hazards. A checklist should be devised to assist you or your team in identifying hazards.

Presenter

Presentation Notes

Your employer is responsible to assign a competent person for each excavation to ensure that they are properly classified and that adequate protective systems have been placed into service. Inspections are the basis for recognizing hazards that either exist or are considered predictable. A Competent Person must inspect the site prior to the start of work and as needed throughout the shift for evidence of a potential cave-in, for indications of impending failure of protective systems--such as shoring, shielding, sloping--and for any other potentially hazardous atmospheres. The competent person must also complete an inspection after a change in conditions or after any hazard causing event, like a rainstorm or surface water run-off. In addition, the workers and the job supervisor should also be trained to recognize hazards. A checklist should be devised to assist you or your team in identifying hazards.


Perimeter Access/Walkways • Bridges or walkways must always be used when

– Crossing an open cut – Accessing a structure from the edge of the trench

• Walkways 6 feet up and more require handrails. • Always use the walkway provided. • Never jump across the trench as a shortcut.

Safety Tip: California has added the special requirement that the trench must be 30 inches across or wider to require the bridge crossing.

Presenter

Presentation Notes

Your employer is also responsible to protect workers that must transition around excavation hazards. This may include the installation of bridges or walkways which must always be used when crossing an open cut or accessing a structure from the edge of the trench. The walkway must have handrails when walkways are 6 feet or more above lower levels. It is your responsibility to safely use walkways that are provided and to never jump across the trench as a shortcut.

Summary

Summary • We have now completed our discussion of the

hazards of trenching and related OSHA safety standards, including those regarding: – Classification of soils – Air monitoring – Trench and excavation access – Spoils piles – Shoring and sloping – Subpart P - Excavations

Presenter

Presentation Notes

We have now completed our discussion of the hazards of trenching and related OSHA safety standards, including those regarding: classification of soils, air monitoring, safe access, spoils piles, shoring and sloping We have reviewed the provisions of subpart P the OSHA Excavation standard. We have also introduced the various appendices of the standard which are key in implementing safe trenching and excavating operations. This completes your course on excavation safety.

excavation safety€“ trench and excavation access – spoils piles – shoring and sloping •...

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