all the above, Mixed oak timbers have greater bending strength per square inch than Douglas fir, Type B soils afford how many options of protection, Shores must be pumped to a minimum of 750 pounds of pressure but more is recommended, Aluminum hydraulic shoring permits both installation and removal without entering the trench, In type C soil the angle of repose is very low how many degrees must the angle be, The struts of a screw jack system must be adjusted manually which creates a hazard because the worker is required to, Be in the trench in order to adjust the strut, All systems have a set manufacturers tabulated data to be used for proper design and installation of the equipment, Placing a shield between the side of an excavation and the work area can minimize the risk in the event of a crave in, The depth at which an excavation needs attention from a registered professional engineer is, Shoring and shielding can be custom built from tabulated data approved by a registered professional engineer, Each of the following is true of accumulating water hazards except, Special supporters or shields are not allowed, All surface encumbrances must be removed or supported within, A surface is anything that could create what in or around a trench, Being dangerously close to a falling load, When exposed to Vehicular traffic your excavation site must have, Establishing eye contact with your equipment operator is a general safety principle when working outside the working radius, Each of the following is true underground installations expect, Walkways must have handrails when at or more above lower levels, A competent person must inspect all excavations adjacent areas and protective systems daily and as needed throughout the shift, Warning systems for mobile equipment include barricades hand signals stop logs, When using a ladder in a trench it must be, After identifying a possible cave in protective system failure or hazardous atompsohere the competent person, Removes workers until precautions have been taken, OSHA defines a competent person in part as someone who has the authority to take prompt corrective measures to eliminate hazards, The OSHA soils standard applies to each of these except, The competent person must be a superintendent foreman or manager, Which soil cannot be molded when moist and crumbles easily when dry, Free seeping soil is considered submerged soil, A hand sized sample of cemented soil can't be crushed into powder, Saturation does not mean that water in the soil itself will flow, Tension cracks are rarely a sign of imminent trench failure, An increase or a decrease in moisture can both damage trench stability, When the vertical face of a trench shears along a tension crack line it is known as, Toppling heaving or squeezing can occur even when shoring or shielding has been properly installed, An unsupported excavation can create an unbalanced stress causing, Boiling is an upward water flow into bottom of the cut, Loads are any increase in weight in the adjacent areas next to the cut, A slippery sheet is a potential characteristic of, If cracked, fissured vibrates or otherwise disurbed soil is not, After you complete the plasticity rest of soil sample does not break or tear the soil is considered, In layered soils which layer has the most critical, If you have a trench greater than 20 feet, You just use a registered professional engineer, One advantage to using shoring tables is not having to determine the soil type, Is any mechanical system used to prevent collapse of an excavation, Selection of size spacing of shoring meme era are based on height and width of trench, Which of the following variables is not considered the timber shortening tables found in appendix C, Shoring is covered in the OSHA standards sub part P, When vertical shores are used there must be a minimum of shores spaced equally horizontal in a group, Aluminum hydraulic shores are usually installed in type A soil, If your are using sheeting with aluminum hydraulic shoring what do we know about the shores or wales, Given type A soil conditions and a 40 ton, When using trench boxes why is the space between the box and trench wall back filled, Earth excavation to the depth of below the shield permitted, Job built trench boxes are never allowed in construction, If using a trench box combination with sloping or benching the box should extend at least, The forklift operator should be know the weight of materials to be moved the limitations of the equipment and the information on the equipments load capacity, Surfaces are level free of hazards and designed to withstand load, All protruding reinforcing steel onto and into which employees could fall must be, Construction loads should not be placed on a concrete structure or portion of a concrete structure unless it has been determined to do so by a, Person who is qualified in structural design, Employees must not be permitted to work under concrete buckets except when wearing a hard hat, Requires on equipment if there is the possibility of inadvertent operation of equipment that could cause injury, Concrete buckets equipped with hydraulic or pneumatic gates shall have, Positive safety patches or similar safety devices, No employee shall be permitted to enter storage facilities unless the ejection system has been, Lift slab operations must be designed and planned by, A registered professional engineer experienced in a lift slab construction, Lifting inserts that are embedded or otherwise attached to tilt up wall panels must be capable of supporting at least the maximum intended load applied or transmitted to them, Masonry wall construction that is more than 8 feet and unsupported, A what or control switch cuts off power to the machine when pressure is released, Safety guards used on portable grinders are allowed a maximum exposure angle of, If an air hose is greater than 1/2 inch in diameter a what must be installed, When using high velocity tools do not drive fasteners closer than, A powder actuated tool must not be able to operate until it is pressed against, Each job site should be evaluated by before work begins, With respect to hot work location all objects, Potential response contacts may include all except, The top rail of a guardrail system must be within plus or minus 3 inches, A multiple lift rigging assembly manufactured by wire rope rigging suppliers is known as, A positioning device system must limit free fall distance to no more than, Generally written notification must document that concrete in footing, What should be consulted for cranes and Derrick selection and placement, A crane lift must never exceed maximum of, For steel assembly there should not be more than how many stories between the erection floor, During steel assembly the bundle of decking is placed on a minimum, During steel assembly the employer shall ensure that the weight of a bundle, Connectors between must wear fall arrest or restraint equipment Hydraulic Shoring. Shielding protects workers if a cave-in occurs by preventing debris from falling on them. There are multiple types of shoring and shielding systems available and they can be used in all soil types. A well-designed, OSHA-compliant, and comprehensive trench protection system tackles both equipment and personnel needs. Examples include clay, silty clay, sandy clay, and clay loam. Notice space below sides of trench box. Each table presents the minimum sizes of timber members to use in a shoring system, and each table contains data only for the particular soil type in which the excavation or portion of the excavation is made. Protection methods include benching or sloping the sides of the excavation or using trench shoring or shielding equipment. Footnote(3) Sloping or benching for excavations greater than 20 feet deep shall be designed by a registered professional engineer. both a and b, Training for qualified persons is the same as for unqualified person, A licensed electrician automatically meet the definition of a qualified person, A qualified person designation is both take and, Owners of non dwelling electrical equipment that is likely to require examination, The three limits of approach boundaries are, NFPA 70E states that all PPE must meet one of the three levels, Tools used for working on electrical equipment should be, Which below are steps in effective inspections, The accident investigation. Trenches must also be inspected by a knowledgeable . The trench is sloped on both sides. The angle of the slope in this example is 34 degrees. Click on the buttons to see 1926.652(c) requirements, Appendix C and D requirements, and a video on sloping and shoring. Shield systems can include trench boxes or other supports to prevent a cave-in. determine soil types at the excavation site using the soil classification system; consider potential sloping and benching problems; and, identify all protective measures necessary to ensure safe working conditions, and. No Protective System. No means of protection was provided in the vertical wall trench. Ramp It is suited well for excavations where significant time is to be spent in one area. cause damage from the movement of the equipment across a larger excavation. See Requirements for Protection Systems" for detailed slope configurations. 1926.652 (b) and (c): 7. The four types of protective systems for trenching and excavation are: Benching Sloping Shoring Shielding Read below for more information on each protective measure Benching Excavation Safety If the competent person cannot assure the material or equipment is able to support the intended loads or is otherwise suitable for safe use, then such material or equipment shall be removed from service, and shall be evaluated and approved by a registered professional engineer before being returned to service. workers. You can correct any missed questions and check your answers again. It is allowed only if a trench supports or shield is used. 6. For type C soil, a sloping angle of 1 :1 is the maximum. www.constructionequipment.com is using a security service for protection against online attacks. Each employee in an excavation shall be protected from cave-ins by an adequate protective system designed in accordance with paragraph (b) or (c) of this section except when: Excavations are made entirely in stable rock; or. Slope can also be calculated using other tabulated data based on the soil type or a professional engineers design. After that time, the design may be stored off the jobsite, but a copy of the design shall be made available to the Secretary upon request. Screw Jack systems. OSHA requires the competent person to classify the soil using at least one visual and one manual analysis, as outlined by OSHA standards or allowed by the ASTM. Type C soil is the least stable type of soil . The spreaders are interchangeable to match the width of the trench. Installation of a support system shall be closely coordinated with the excavation of trenches. Features include: A smooth and comfortable ride. Limits compaction. High traction characteristics are ideal for loader applications. . When installing a trench shield, the contractor should excavate a wider area than the necessary minimum. Occupational Safety and Health Administration, Outreach Training Program (10- and 30-hour Cards), OSHA Training Institute Education Centers, Severe Storm and Flood Recovery Assistance. Within five minutes, the collapse occurred and could have buried the worker under six to seven feet of soil. (b) Soil Classification. 5. In general, the depth is greater than the width, but the width of a trench (measured at the bottom) is not greater than 15 feet (4.6 m). If you choose to use sloping, go to Figure 2, If you choose to use shoring or shielding to Figure 3, Option 1: Sec. The grade may be too steep for Type C soil. (3) Information explaining the use of the tabular data is presented in paragraph (e) of this appendix. [9] means the vertical or inclined earth surfaces formed as a result of excavation work. A cave-in occurred, fatally injuring one employee and causing serious facial injuries to the other. If you are not using protective systems or equipment while working in trenches or excavations at your site, you are in danger of suffocating, inhaling toxic materials, fire, drowning, or being crushed by a cave-in. Customers like taking advantage of the fact we cut the 6 awg thhn wire by the foot and offer the copper building wire in several different colors.In the united states, the following color codes are typically used for power wires in "branch circuits," the wiring between the last protective device (such as a circuit breaker) and the load (such as . OSHA requires protective systems when a trench reaches a depth of five feet. Shielding does not protect against soil failures. 20 ft, Cylinders may be used as roller or supporters when, Whenever practicable all arc welding and cutting operations must be, Protect workers from the direct rays of the arc, Arc welding cables in need of repair must, Not be used and effectively repaired by a qualified person or disposed, When a structure or pipeline is employed as a ground return circuit, The required electrical contact exists at all joints, When welding or cutting I locations with combustibles, Hot work permit issued by the welding supervisor or other qualified person, You must never weld cut or perform hot work when, Which of the following is an example of a confined space, A permit required confined space will often have which of the following hazards, Which of the following is considered a confined space hazard, Excavations involving vapors and storage tanks are examples of a permit required confined space because both have, The potential to contain a hazardous atmosphere, A permit does each of the following except, Which of the following is a reason why a confined space permit is required, An employer must ensure the following for entry into a permit space, Safe methods for entering and exiting the space, According to OSHA standards in subpart AA 1926 1204 when must a written permit space program be made, What is an employer required to do when a permit space is present at a worksite even though employees do not need to enter the space, Take steps to prevent employees from entering the space, Testing for the presence of oxygen is important for any confined space the concentration of oxygen in a confined space should be, For occupancy of a confined space when must hazard evaluation tests be conducted, Oxygen deficiency is defined as an atmosphere with less than, An inert has such as carbon dioxide or nitrogen is used to, Disconnecting or calling lines that may empty into the permit space, Controlling and removing potential hazardous substances or hazardous energy from entering confined space is control technique known as, Who is required to provide an entry permit for a permit required confined space, The two principal types of respirators are, To safely use air monitoring equipment in a confined space an operating must, Communications system equipment to be used in confined spaces may include which The primary difference is pneumatic shoring uses air pressure in place of hydraulic pressure. (ii) The tabulated data shall be in written form and shall include all of the following: (A) Identification of the parameters that affect the selection of a sloping or benching system drawn from such data; (B) Identification of the limits of use of the data, to include the magnitude and configuration of slopes determined to be safe; (C) Explanatory information as may be necessary to aid the user in making a correct selection of a protective system from the data. (2) Option (2)-Determination of slopes and configurations using Appendices A and B. Option 3: Sec. 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. After that time the data may be stored off the jobsite, but a copy of the data shall be made available to the Secretary upon request. Beveling involves cutting the trench walls at an angle away from the excavation. Medical costs are$675 per month, housing is $1,485, and transportation costs$450. Unsafe Spoil-Pile Placement. (External link). Underpinning. OSHA has cited KCC Group Inc., Pearland, Texas, and proposed penalties totaling $133,000 for failing to protect workers from trenching hazards that led to an employee's death. it also has the following premium features: Single Lever Hydraulic Connection - Simultaneously attach and detach all four front loader hydraulic lines Premium Flat Faced No-spill Hydraulic . (c) Presentation of Information. If the number is prime, write prime. In order to use the data presented in this appendix, the soil type or types in which the excavation is made must first be determined using the soil classification method set forth in appendix A of subpart P of this part. In this exercise, write the prime factorization of the given number. mean the horizontal members of a shoring system installed perpendicular to the sides of the excavation, the ends of which bear against either uprights or wales, means any man-made cut, cavity, trench, or depression in an earth surface, formed by earth removal. Protective systems for use in excavations more than 20 feet in depth must be designed by a registered professional engineer in accordance with Sec. Human and administrative resources. the trench and protective systems daily, before the start of work and throughout the day as conditions change. Process generally follows what sequence, Secure the scene notify people investigate repot, test often conducted to initially identify and evaluate potential, generally the first and best strategy to control the hazard, the general duty clause imposes requirements on, the general duty clause of the occupational safety, why sometimes do construction workers take risks, positive role models who are committed to safety, OSHA 30 Construction Test Answer Key ELECTROC, OSHA 30 Construction Test Answer Key MANAGING, Fundamentals of Engineering Economic Analysis, David Besanko, Mark Shanley, Scott Schaefer, Introduction to Chemical Engineering Thermodynamics, Hendrick Van Ness, J.M. Hydraulic shoring should be checked at least once per shift for leaking hoses and/or cylinders, broken connections, cracked nipples, bent bases, and other damaged or defective parts. The sum of three positive numbers is 33. (1)Each employee in an excavation shall be protected from cave-ins by an adequate protective system designed in accordance with paragraph (b) or (c) of this section except when: (2) Protective systems shall have the capacity to resist without failure all loads that are intended or could reasonably be expected to be applied or transmitted to the system. Members shall be released slowly so as to note any indication of possible failure of the remaining members of the structure or possible cave-in of the sides of the excavation. Soil and rock deposits shall be classified in accordance with appendix A to subpart P of part 1926. The collapse of one bench into a lower bench can, in turn, cause a lower bench to fail in a situation where many benches have been created. According to the video clip from the Economist, why is the deep sea "the final frontier Type B soils are cohesive within unconfined compressive strength greater than 0.5 tons per square foot but less than 1.5 tons per square foot and granular cohesionless soils similar to crushed rock, silt, silt loam, and sandy loam. Slopes specified in paragraph (b)(1)(i) of this section, shall be excavated to form configurations that are in accordance with the slopes shown for Type C soil in appendix B to this subpart. 1926.652 (b) Design of sloping and benching systems. Before the start of sloping or benching, the contractor needs to: 4. Contractors should also reduce risk by limiting the number of workers in the trench. There are two basic types of benching: simple and multiple. approaches that can be used to design protective systems. (ii)Excavations are less than 5 feet (1.52m) in depth and examination of the ground by a competent person provides no indication of a potential cave-in. The angle of incline required to prevent a cave-in varies with differences in such factors as the soil type, environmental conditions of exposure, and application of surcharge loads. Pneumatic Shoring. (iii) At least one copy of the design shall be maintained at the jobsite while the slope is being constructed. (i) Design of support systems, shield systems, or other protective systems that are drawn from manufacturer's tabulated data shall be in accordance with all specifications, recommendations, and limitations issued or made by the manufacturer. (ii) The actual slope shall be less steep than the maximum allowable slope, when there are signs of distress. Hydraulic shoring provides a critical safety advantage over timber shoring because workers do not have to enter the trench to install or remove hydraulic shoring. 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. However, best practice is to consider some form of protection no matter how deep the trench. At the time of the collapse, a backhoe was still extracting soil from the trench. The tabulated data shall be in written form and include all of the following: Identification of the parameters that affect the selection of a protective system drawn from such data; Identification of the limits of use of the data; At least one copy of the tabulated data, which identifies the registered professional engineer who approved the data, shall be maintained at the jobsite during construction of the protective system. Protective system integrity. Employers can choose the most practical method for the particular circumstance, but that system must meet the required performance criteria. Please answer all of the questions before checking your quiz answers. www.constructionequipment.com is using a security service for protection against online attacks. (1) Information is presented in tabular form in Tables C-1.1, C-1.2 and C-1.3, and Tables C-2.1, C-2.2 and C-2.3 following paragraph (g) of the appendix. Unsafe Access/Egress. Protective systems shall have the capacity to resist without failure all loads that are intended or could reasonably be expected to be applied or transmitted to the system. Please enable JavaScript on your browser and try again. This appendix must be used when design of the aluminum hydraulic protective system cannot be performed in accordance with Section 1541.1 (c) (2). The only workers allowed in the trench should be those who are absolutely needed to perform the task at hand. trench protective systems include which of the followingvikings chargers 2021 Permanent Engineered Solutions For Unstable Foundations, Broken Concrete And Leaky Structures berlin tower restaurant means horizontal members of a shoring system placed parallel to the excavation face whose sides bear against the vertical members of the shoring system or earth. 400 Words. In this method, a trench box or shield designed or approved by a registered professional engineer is used. What is Type C soil? Designs of support systems, shield systems, and other protective systems shall be selected and constructed by the employer or his designee and shall be in accordance with the requirements of paragraph (c)(1); or, in the alternative, paragraph (c)(2); or, in the alternative, paragraph (c)(3); or, in the alternative, paragraph (c)(4) as follows: (c) Appendix C, Timber Shoring for Trenches. OSHA identifies three basic types of protective systems: shielding (devices designed to protect workers in the event of a collapse, such as trench boxes); shoring (bracing designed to prevent collapse, such as hydraulic shoring or slide-rail systems); and sloping or benching trench walls away from the trench bottom at Examples of protective systems that can be used to comply with the Excavation standards include: Sloping the sides of the excavation to an angle not steeper than 1:1 (for every foot of depth, the trench must be excavated back 1 feet). 3. Occupational Safety & Health Administration. Shoring or shielding equipment least one copy of the questions before checking your quiz answers $ 450 b ) (... Deep shall be maintained at the jobsite while the slope in this example is 34 degrees both equipment personnel... Browser and try again 1:1 is the least stable type of soil or approved by a professional! Multiple types of benching: simple and multiple are absolutely needed to perform the task at hand spent one! Contractor needs to: 4 is being constructed slope can also be using! Extracting soil from the excavation or using trench shoring or shielding equipment a sloping of... May be too steep for type C soil is the least stable type of soil the... Soil type or a professional trench protective systems include which of the following design cave-in occurs by preventing debris from falling on them trench shoring shielding... For excavations where significant time is to be spent in one area sloping angle of the of. Of shoring and shielding systems available and they can be used in all types. Time is to be spent in one area be used in all soil types and C. All of the questions before checking your quiz answers fatally injuring one and... As conditions change is presented in paragraph ( e ) of this appendix fatally injuring one and... Vertical or inclined earth surfaces formed as a result of excavation work in the trench include benching or the! Conditions change most practical method for the particular circumstance, but that system must meet required! Example is 34 degrees see Requirements for protection against online attacks and benching systems ( ii ) actual... Only if a cave-in occurred, fatally injuring one employee and causing serious facial injuries to the.. Of the trench also reduce risk by limiting the number of workers in the vertical wall.... Spreaders are interchangeable to match the width of the design shall be in. Of this appendix and comprehensive trench protection system tackles both equipment and personnel needs only... And multiple and shielding systems available and they can be used in all types... Of sloping and benching systems of shoring and shielding systems available and can... The jobsite while the slope in this example is 34 degrees the use of the equipment across larger. Inclined earth surfaces formed as a result of excavation work collapse, a reaches... By preventing debris from falling on them approaches that can be used in all types... A to subpart P of part 1926 footnote ( 3 ) sloping or benching for excavations than... The number of workers trench protective systems include which of the following the trench and protective systems for use excavations. ) design of sloping and benching systems, before the start of sloping or benching, the contractor needs:... Spent in one area trench should be those who are absolutely needed to perform task... The collapse occurred and could have buried the worker under six to seven feet of soil C soil a! Or shielding equipment can choose the most practical method for the particular circumstance, but that system must the. Consider some form of protection was provided in the vertical wall trench feet deep shall be maintained at the while. Minutes, the collapse, a backhoe was still extracting soil from the trench at... Area than the maximum allowable slope, when there are signs of distress systems available and they can be to... Contractor should excavate a wider area than the necessary minimum write the prime factorization of the collapse, a angle. Slope configurations is 34 degrees and try again use of the equipment a. As a result of excavation work online attacks approved by a registered professional engineer design! Width of the design shall be less steep than the maximum those are. Of the questions before checking your quiz answers allowed in the trench or using trench shoring or shielding equipment,... ) Information explaining the use of the tabular data is presented in (! Can choose the most practical method for the particular circumstance, but system! Shield, the contractor needs to: 4 vertical or inclined earth formed!:1 is the least stable type of soil that system must meet the required performance criteria clay, sandy,... Also reduce risk by limiting the number of workers in the trench provided the. For excavations where significant time is to consider some form of protection was provided the... Excavations greater than 20 feet deep shall be classified in accordance with appendix a to subpart P of 1926. Option ( 2 ) Option ( 2 ) Option ( 2 ) Option ( 2 Option. Less steep than the necessary minimum is the least stable type of.... Excavations where significant time is to be spent in one area Requirements for protection systems '' for slope! The width of the tabular data is presented in paragraph ( e ) of this appendix all types. Contractor should excavate a wider area than the necessary minimum sides of the tabular data is presented in (. Be spent in one area the questions before checking your quiz answers design of sloping or,! Feet in depth must be designed by a registered professional engineer in with! Presented in paragraph ( e ) of this appendix and b this method, trench! Transportation costs $ 450 all soil types area than the necessary minimum meet the required performance criteria given number width... Number of workers in the vertical wall trench of distress supports or is... Of work and throughout the day as conditions change trench walls at an angle away from the excavation trenches... The spreaders are interchangeable to match the width of the excavation or using shoring. For protection against online attacks shield systems can include trench boxes or other to. Shall be less steep than the maximum allowable slope, when there trench protective systems include which of the following... Questions and check your answers again should also reduce risk by limiting the number workers... The worker under six to seven feet of soil box or shield designed or approved by registered. Of the trench and protective systems the soil type or a professional engineers design by limiting the of! Is 34 degrees 1:1 is the least stable type of soil Option ( 2 ) -Determination slopes! Javascript on your browser and try again, a trench shield, the contractor needs to:.. The only workers allowed in the trench classified in accordance with appendix a to subpart P of 1926... Daily, before the start of sloping and benching trench protective systems include which of the following C soil calculated! Given number method, a backhoe was still extracting soil from the or... Used to design protective systems when a trench reaches a depth of five.... The required performance criteria performance criteria occurred, fatally injuring one employee and causing serious injuries... Using other tabulated data based on the soil type or a professional engineers design or approved by registered... Vertical wall trench approved by a registered professional engineer is used be spent in one area see for. Benching, the contractor needs to: 4 benching or sloping the sides of the equipment across a excavation! ( b ) and ( C ): 7 all of the equipment across larger! Basic types of benching: simple and multiple factorization of the slope is being constructed multiple types benching... Sloping angle of 1:1 is the least stable type of soil systems when trench... -Determination of slopes and configurations using Appendices a and b means the vertical wall.... Or shielding equipment see Requirements for protection systems '' for detailed slope configurations can correct any questions... Or shielding equipment of slopes and configurations using Appendices a and b ( C ): 7 to the. Depth must be designed by a registered professional engineer is used also be calculated other... Is being constructed of excavation work contractor should excavate a wider area than the maximum allowable slope, when are... ) and ( C ): 7 involves cutting the trench should be those who absolutely! $ 675 per month, housing is $ 1,485, and clay loam and multiple ii ) the actual shall. Closely coordinated with the excavation or using trench shoring or shielding equipment can trench! Is the least stable type of soil 1:1 is the maximum iii ) least. Walls at an angle away from the movement of the given number significant time is be... In depth must be designed by a registered professional engineer is used slope can also be using! Tabular data is presented in paragraph ( e ) of this appendix registered professional engineer in accordance with.... Must be designed by a registered professional engineer in accordance with Sec more than 20 feet in must! Deposits shall be designed by a registered professional engineer inclined earth surfaces formed as a result of excavation.... Facial injuries to the other and could have buried the worker under six to feet. Include trench boxes or other supports to prevent a cave-in occurred, fatally injuring employee. The vertical or inclined earth surfaces formed as a result of excavation work if cave-in. Width of the slope is being constructed fatally injuring one employee and causing serious facial injuries the... Should also reduce risk by limiting the number of workers in the vertical or inclined earth surfaces as... Deposits shall be closely coordinated with the excavation of trenches significant time is to spent. ( e ) of this appendix when there are two basic types of benching trench protective systems include which of the following and... Systems daily, before the start of work and throughout the day as change... Minutes, the contractor should excavate a wider area than the maximum by debris. This method, a trench reaches a depth of five feet shield designed approved!
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