OSHA 30 - Excavation Hazards Flashcards
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Questions and Answers

A cubic yard of soil can weigh as much as:

  • A motorcycle
  • A large sedan
  • A bicycle
  • A small pickup truck (correct)

    • To be classified as type A, the soil cannot be:

  • Subject to vibration (correct)
  • Part of a mixed layered system (correct)
  • Disturbed (correct)
  • Seeping water (correct)

    • When your trench is deeper than 4 ft and hazards may be present, air monitoring must be done before entry.

    True (A)

    A soil cannot be Type A if it is:

    <p>All of the above (D)</p> Signup and view all the answers

    Which of the following are common soil classification tests?

    <p>Atterberg limits (A), Plasticity test (C), Unconfined compression test (D)</p> Signup and view all the answers

    Type A soils are usually clay and cemented soils such as caliche and hardpan.

    <p>True (A)</p> Signup and view all the answers

    Each of the following is Type B soil EXCEPT:

    <p>Sand (A)</p> Signup and view all the answers

    The definition of type C-60 soil allows the competent person to use vertical shores or other protective systems.

    <p>True (A)</p> Signup and view all the answers

    What is the most important distinction between stable rock types A&B and type C?

    <p>Degree of stability</p> Signup and view all the answers

    What is a defining feature of stable rock?

    <p>Remain intact while exposed</p> Signup and view all the answers

    OSHA requires a competent person to perform two visual and two manual tests on a soil sample.

    <p>False (B)</p> Signup and view all the answers

    Aluminum hydraulic shoring permits both installation and removal without entering the trench.

    <p>True (A)</p> Signup and view all the answers

    Shores must be pumped to a minimum of 750 pounds of pressure but more is recommended.

    <p>True (A)</p> Signup and view all the answers

    Type B soils afford how many options of protection?

    <p>Four</p> Signup and view all the answers

    Which soil type is the most common?

    <p>Type B</p> Signup and view all the answers

    Which of the following statements is true of kickout?

    <p>All of the above (D)</p> Signup and view all the answers

    Mixed oak timber has a greater bending strength per square inch than Douglas fir.

    <p>False (B)</p> Signup and view all the answers

    In type C soil, the angle of repose is very low. How many degrees must the angle be?

    <p>34</p> Signup and view all the answers

    What is the depth at which an excavation needs attention from a registered professional engineer?

    <p>20 ft</p> Signup and view all the answers

    Placing a shield between the side of an excavation and the work area can minimize the risk in the event of a cave-in.

    <p>True (A)</p> Signup and view all the answers

    Shoring and shielding can be custom built from tabulated data approved by a registered PE.

    <p>True (A)</p> Signup and view all the answers

    The struts of a screw jack system must be adjusted manually; this creates a hazard because the worker is required to:

    <p>Be in the trench in order to adjust the strut</p> Signup and view all the answers

    All systems have a set of manufacturer's tabulated data for proper design and installation.

    <p>True (A)</p> Signup and view all the answers

    When using a ladder in a trench, it must be:

    <p>All of the above (D)</p> Signup and view all the answers

    A surface encumbrance is anything that could create a ___ in or around a trench.

    <p>hazard</p> Signup and view all the answers

    Walkways must have handrails when at ___ or more above a lower level.

    <p>6 ft</p> Signup and view all the answers

    A competent person must inspect all excavations, adjacent areas, and protective systems daily, ___, and as needed throughout the shift.

    <p>Before work begins</p> Signup and view all the answers

    Establishing eye contact with your equipment operator is a general safety principle when working outside the working radius.

    <p>True (A)</p> Signup and view all the answers

    Being dangerously close to a falling load is allowed.

    <p>False (B)</p> Signup and view all the answers

    Each of the following is true of accumulating water hazards EXCEPT:

    <p>Special supports or shields are not allowed. (B)</p> Signup and view all the answers

    Warning systems for mobile equipment include barricades, hand signals, and stop logs.

    <p>True (A)</p> Signup and view all the answers

    All surface encumbrances must be removed or supported within:

    <p>The zone of influence</p> Signup and view all the answers

    Each of the following is true of underground installations EXCEPT:

    <p>They must be removed if damaged. (C)</p> Signup and view all the answers

    When exposed to vehicular traffic, your excavation site must have:

    <p>All of the above (D)</p> Signup and view all the answers

    Which of these did OSHA recommend?

    <p>Provide ladder if trench 4 ft or more in depth (A), Employers must instruct employees on hazard recognition (B), Keep excavated material 2 ft from excavation (C), Protect walls to prevent cave-ins (D)</p> Signup and view all the answers

    The competent person must have authority to correct hazards. Who gives the competent person this authority?

    <p>The person's employer</p> Signup and view all the answers

    The competent person must be a superintendent, foreman, or project manager.

    <p>False (B)</p> Signup and view all the answers

    The topic is about the practical application of the Fed-OSHA Excavation standard regarding:

    <p>All of the above (D)</p> Signup and view all the answers

    After identifying a possible cave-in, protection system failure, or hazardous atmosphere, the competent person:

    <p>Removes workers until precautions have been taken</p> Signup and view all the answers

    The OSHA Soils Standard applies to each of these EXCEPT:

    <p>Offshore petroleum drilling (D)</p> Signup and view all the answers

    What do you think was the primary cause of this accident?

    <p>Unstable soil due to accumulation of water</p> Signup and view all the answers

    What could have been done to prevent this fatality?

    <p>Shore, slope, sheet or brace the trench walls; have a competent person inspect the trench daily; do not allow water to accumulate in the trench.</p> Signup and view all the answers

    "Free-seeping" soil is considered submerged soil.

    <p>False (B)</p> Signup and view all the answers

    Which soil cannot be molded when moist and crumbles easily when dry?

    <p>Granular soil</p> Signup and view all the answers

    Soil which fractures along definite planes or exhibits open cracks is:

    <p>Fissured soil</p> Signup and view all the answers

    OSHA made four recommendations in which responsibility was clearly identified. To whom were OSHA's recommendations directed?

    <p>The employer</p> Signup and view all the answers

    An unsupported excavation can create an unbalanced stress, causing:

    <p>All of the above (D)</p> Signup and view all the answers

    When the vertical face of a trench shears along a tension crack line, it is known as:

    <p>Toppling</p> Signup and view all the answers

    Tension cracks are rarely a sign of imminent trench failure.

    <p>False (B)</p> Signup and view all the answers

    Boiling is an upward water flow into the bottom of the cut.

    <p>True (A)</p> Signup and view all the answers

    Having or squeezing can occur even when shoring or shielding has been properly installed.

    <p>True (A)</p> Signup and view all the answers

    An increase or decrease in moisture can both damage trench stability.

    <p>True (A)</p> Signup and view all the answers

    Time and weather are not major influences in soil stress.

    <p>False (B)</p> Signup and view all the answers

    The 'adjacent area' is the area on either side of the trench cut equal to the depth of the trench.

    <p>True (A)</p> Signup and view all the answers

    Layered systems may have layers of different soil types, which become especially problematic when layers slope or dip downward.

    <p>True (A)</p> Signup and view all the answers

    ____ loads are any increased in weight in the adjacent areas next to the cut.

    <p>Surcharge</p> Signup and view all the answers

    About how much does one cubic yard of soil weight?

    <p>3000 lb</p> Signup and view all the answers

    When should type A be downgraded to type B or lower?

    <p>All of the above (D)</p> Signup and view all the answers

    For testing, soil suspected to be Type A should:

    <p>All of the above (D)</p> Signup and view all the answers

    Granular soils without cohesion, such as crushed rock, are typically type B soil.

    <p>True (A)</p> Signup and view all the answers

    Type C soils are rated below 0.5 tsf (tons per square foot).

    <p>True (A)</p> Signup and view all the answers

    Unconfined Compressive Strength is determined by:

    <p>Any of the above (D)</p> Signup and view all the answers

    The error rate of the pocket penetrometer is between 20% and:

    <p>40%</p> Signup and view all the answers

    After you complete the plasticity (wet thread) test, if soil sample does not break or tear, the soil is considered:

    <p>Cohesive</p> Signup and view all the answers

    A common visual test is to:

    <p>All of the above (D)</p> Signup and view all the answers

    Soil that crumbles freely or with moderate hand pressure into individual grains is granular, according to:

    <p>The dry strength test</p> Signup and view all the answers

    For trenching and excavations, a competent person must have knowledge of:

    <p>All of the above (D)</p> Signup and view all the answers

    Before excavating material, each of the following is true of underground utilities EXCEPT:

    <p>They must always be removed (C)</p> Signup and view all the answers

    When using ladders for egress from a trench, they must:

    <p>All of the above (D)</p> Signup and view all the answers

    In trenches, each of the following is true of accumulating water hazards EXCEPT:

    <p>Special supports or shields are not allowed. (A)</p> Signup and view all the answers

    Unclassified soil is considered no better than which soil classification?

    <p>Type C</p> Signup and view all the answers

    Even if you are using a trench shield, all ejected spoils material still need to be at least ___ ft away from the edge of the slope at the top.

    <p>2</p> Signup and view all the answers

    No major structural repairs may be performed on an excavation protective system without permission from the manufacturer or engineer.

    <p>True (A)</p> Signup and view all the answers

    Which conditions prevent soil from being classified as type A soil?

    <p>Both A and B (C)</p> Signup and view all the answers

    What is the minimum need to properly classify soil under the Construction OSHA Standard, Subpart P?

    <p>One visual and manual test</p> Signup and view all the answers

    Which of the following is specified by the construction OSHA standard, subpart P, sloping requirements for excavations?

    <p>Type A soil must be sloped at 3/4 to 1 or less (A)</p> Signup and view all the answers

    Assign a classification of type B to the soil. If you protect this excavation by sloping it, how wide is the excavation at the top?

    <p>34</p> Signup and view all the answers

    You are excavating for a 24-inch water line. What is the soil type?

    <p>Type C</p> Signup and view all the answers

    If you have a trench greater than 20 ft deep:

    <p>You must use a registered professional engineer</p> Signup and view all the answers

    In most cases, Type A soil can be sloped up to:

    <p>3/4:1 (D)</p> Signup and view all the answers

    In most cases, Type C soil can be sloped up to:

    <p>1:1 (B)</p> Signup and view all the answers

    One advantage to using shoring tables is not having to determine the soil type.

    <p>False (B)</p> Signup and view all the answers

    Selection of size and spacing of shoring members are based on height and width of trench.

    <p>False (B)</p> Signup and view all the answers

    Shoring is any mechanical system used to prevent collapse of an excavation.

    <p>True</p> Signup and view all the answers

    Which of the following variables is not considered in the timber shoring tables found in appendix C?

    <p>Slope of excavation (D)</p> Signup and view all the answers

    Shoring is covered in the OSHA standards subpart P:

    <p>Both A and B (C)</p> Signup and view all the answers

    One advantage to using shoring tables is not having to determine the soil type.

    <p>False (B)</p> Signup and view all the answers

    When vertical shores are used, there must be a minimum of ___ shores spaced equally, horizontally, in a group.

    <p>Three</p> Signup and view all the answers

    The decision whether to use sheeting with aluminum hydraulic shoring depends primarily on:

    <p>True (A)</p> Signup and view all the answers

    Given Type A soil, dry conditions, and a 40-ton piece of equipment near the edge of the trench, what do we know?

    <p>Both B and C (C)</p> Signup and view all the answers

    If you are using sheeting with aluminum hydraulic shoring, what do we know about the shores, or wales?

    <p>They are installed horizontally. (B)</p> Signup and view all the answers

    Aluminum hydraulic shores are usually installed ____ in Type A soil.

    <p>Vertically</p> Signup and view all the answers

    If using a trench box in combination with sloping or benching, the box should extend at least ___ above the adjacent slope.

    <p>18 inches</p> Signup and view all the answers

    Job-built trench boxes are never allowed in construction.

    <p>False (B)</p> Signup and view all the answers

    Earth excavation to a depth of ___ ft below the shield is permitted.

    <p>2</p> Signup and view all the answers

    When 'stacking' trench boxes:

    <p>Both A &amp; C (C)</p> Signup and view all the answers

    When using trench boxes, why is the space between the box and trench wall backfilled?

    <p>To prevent lateral movement of the box</p> Signup and view all the answers

    Trench boxes don't prevent cave-ins, but do protect people.

    <p>True (A)</p> Signup and view all the answers

    Unconfined compressed strength is the load at which a soil will fail.

    <p>True (A)</p> Signup and view all the answers

    Study Notes

    Excavation Hazards & Soil Classifications

    • A cubic yard of soil can weigh approximately 3,000 lbs, similar to a small pickup truck.
    • Type A soil cannot be disturbed, part of a mixed layered system, subject to vibration, or seeping water.
    • Air monitoring is required before entry in trenches deeper than 4 ft with potential hazards.
    • Stable rock, classified as Types A and B, differs from Type C mainly in stability.
    • Type B soil includes certain sandy soils, while Type C soils are those with low stability and cohesion, rated below 0.5 tsf.

    Soil Testing & Classification

    • Common soil classification tests include visual inspections and manual tests; testing is critical for determining soil type.
    • Type A soils are generally clay and cemented soils like caliche and hardpan.
    • Type B soils offer four options for protective measures, while Type C has the lowest angle of repose at 34 degrees.

    Construction Safety & Protective Systems

    • Protective systems, such as trench shields or boxes, are essential for minimizing risks during excavations.
    • A competent person is responsible for inspecting excavations daily and must have the authority to correct hazards.
    • Shoring systems can be custom-built using approved tabulated data, increasing excavation safety.

    Safety Guidelines for Excavations

    • Excavated materials should be kept at least 2 ft away from the edge of a trench.
    • Walkways require handrails if 6 ft or more above ground level.
    • Warning systems for mobile equipment can include barricades and hand signals to enhance safety at the site.

    Regulations and Responsibilities

    • The OSHA Soils Standard applies to excavation operations, excluding offshore petroleum drilling.
    • Employers are responsible for following OSHA's excavation safety recommendations and ensuring safe working conditions.
    • In cases of unstable soil or other hazards, a competent person must remove workers until safety precautions are implemented.

    Hydration and Soil Conditions

    • Water accumulation can severely compromise trench stability; shoring and sloping strategies must be employed to mitigate such risks.
    • Both increases and decreases in moisture can affect soil stability, making careful monitoring vital.

    Trench Construction Practices

    • Aluminum hydraulic shoring can be installed without trench access, reducing the risk for workers.
    • A minimum of three shores must be used when employing vertical shores for stability.
    • Trench depth exceeding 20 ft mandates consultation with a registered professional engineer for safe excavation practices.

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    Test your knowledge on excavation hazards and soil classifications with these flashcards from the OSHA 30 course. Learn about soil weight, types, and safety requirements for trench entry. Perfect for those preparing for OSHA certification or working in construction environments.

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