Preventing Worker Deaths from Trench Cave-ins

8/6/2019 Preventing Worker Deaths from Trench Cave-ins

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DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and PreventionNational Institute for Occupational Safety and Health

SummaryWorkers are at risk o death romcave-ins during trenching and ex-cavation activities. NIOSH recom-mends engineering controls, pro-tective equipment, and sa e work practices to minimize hazards orworkers.

Preventing Worker Deaths fromTrench Cave-ins

Description ofExposureWorkers who dig or excavate trench-es are at risk o death i they enter anunprotected trench and the walls col-lapse. However, hazards associated withtrench work and excavation are wellde ined and preventable. he OSHAstandard or excavation and trenching,known as 29 CFR* 1926 Subpart P, de-scribes the precautions needed or sa eexcavation work.

Tere is no reliable warning when a

trench ails. Te walls can collapse sud-denly, and workers will not have timeto move out o the way. Even thoughsmall amounts o dirt may not seem

*Code of Federal Regulations. See CFR in Re erences

treacherous, a single cubic yard o dirtcan weigh more than 3,000 pounds,which can atally crush or su ocateworkers [Deatherage et al. 2004]. Evensmall, solid pieces o dirt can cause se-rious injuries.

From 2000−2009, 350 workers died intrenching or excavation cave-ins—an av-erage o 35 atalities per year [BLS 2010].Most incidents involve excavation work

or “water, sewer, pipeline, and commu-nications and power-line construction”[CDC 2004]. An analysis o OSHA data

rom 1997−2001 showed that 64% o a-talities in trenches occurred at depths o less than 10 eet [Arboleda and Abra-ham 2004].

Lack o a protective system was theleading cause o trench-related atali-ties in a review o OSHA inspections[Deatherage et al. 2004]. OSHA requiresthat all excavations 5 eet deep or great-er make use o one o the ollowing pro-tective system options (see Figure 1):(1) sloping the ground; (2) benchingthe ground; † (3) shoring the trench withsupports such as planking or hydraulic jacks, or (4) shielding the trench (using atrench box). Workers should never entera trench that does not have a protectivesystem in place designed and installedby a competent person. ‡

Factors such as type o soil, water con-tent o soil, environmental conditions,proximity to previously back lled ex-cavations, weight o heavy equipmentor tools, and vibrations rom machinesand motor vehicles can greatly a ect soil

† Not all protective systems can be used in all typeso soil. Benching cannot be used in ype C soil.

‡A competent person is one who understands OSHAregulations, can recognize hazards, and is autho-rized to correct them.

Figure 1. Work crew installing waterpipes. Aluminum hydraulic shoring isbeing used as a protective system orthe trench. Photo courtesy of GeorgeKennedy, NUCA.



stability and the hazards that workers ace. When the sides o trenches are shored, the type o soil and width and depth o the trench a ect how ar apart the supports should be spaced.Di erent OSHA regulations apply to the di erent types o supports used or shoring. Consult 29 CFR 1926 Subpart PAppendices C and D or more in ormation. Appendix F pro-

vides a ow diagram or making decisions. Section V, Chap-ter 2 o the OSHA echnical Manual provides a guide on rec-ognizing and preventing trenching and shoring hazards.

Te ollowing case studies, rom the NIOSH Fatality Assess-ment and Control Evaluation Program, describe two atali-ties in which workers su ocated during trench collapses.

Case Studies

Case 1: Male Hispanic Laborer DiesWhen 9-Foot-Deep Trench CollapsesOn February 1, 2006, a 29-year-old male Hispanic labor-er with 5 years o experience died when the 2- oot-wide,16- oot-long, and 9- oot-deep unprotected trench he wasworking in collapsed and covered him with soil during wa-terproo ng work. Te victim and our other laborers, all o whom spoke primarily Spanish and very little English, hadbeen hand digging the trench over a 2-day period at a private residence. Te victim was kneeling to inspect a brokendrain pipe at the bottom o the east end o the trench. Te victim’s brother saw the soil strike the victim and knock hishead against the home’s basement wall. Te trench wall col-lapsed and the victim was completely covered with soil in

seconds. Te victim was pronounced dead at the scene by emergency response personnel. Te company did not have awritten sa ety and health program, competent person on site,or sa ety committee [NIOSH 2006].

Case 2: Construction Laborer Dieswhen Trench Walls CollapseOn November 3, 2003, a 38-year-old male construction la-borer died when the unprotected, 8- oot-high walls o thetrench he was working in collapsed only a ew minutes a -ter he had entered. Te victim was removing an old gas line

that was a 6-inch diameter high pressure line (300–320 psi)in 10-inch steel casing. Five workers were at the job site exca- vating the gas line: a oreman who was a competent person,a lab technician who was a competent person, and 3 labor-ers (including the victim). Te oreman had dug an 8- ootdeep trench with a track hoe to expose the abandoned gasline. A er the gas line was extracted rom its casing, the vic-tim climbed into the trench with a saw to ree the casing, a job that the report indicated would only take a ew minutes.Sloping, benching, or shoring methods were not used to sup-

port the trench. As the laborer began sawing, the sides o thetrench collapsed, burying him. He was declared dead at thescene [NIOSH 2003].

Recommendations[Mulhern and Lentz 2008, 2009]

Employers

Pre-job Planning before the job begins

rain and designate a competent person to ensure sa ety measures are in place.

Call 811 be ore digging so that utility lines can be marked,then “pot-hole” utilities to determine the exact locationand depth be ore digging.

Have a competent person evaluate the soil to determine

its stability. Because soil conditions can vary dramatical-ly over just a ew days, Appendix A o Subpart P providestechniques (roll test and thumb penetration) or evaluat-ing the condition o the soil.

Plan the job layout to identi y sa e locations (away romthe trench) or spoil piles and heavy equipment routes.

Have a competent person determine what type o protec-tive system will be used or the job and schedule the stepsneeded to have the system complete and in place be oreworkers enter.

Note that trenches greater than 20 eet deep can be more

complex, and an engineer should be consulted to deter-mine the appropriate protective system (shoring, shield-ing, or sloping) that should be used.

Ensure that none o the workers designated or entry intothe trench are under age 18.

Ensure that workers involved in the job are trained abouthazards and work practices in a language that they under-stand and at the appropriate literacy level.

Develop a trench emergency action plan [NIOSH 2006]to describe steps to be taken and to provide contact in or-mation in case o an emergency.

Safe operations during the job

Te competent person must inspect the excavation, ad- jacent areas, and protective systems each day be ore thestart o work, as needed throughout the shi , and a er ev-ery rainstorm.

Noti y other subcontractors who come on site o thetrench location and precautions and ensure that vehiclesare kept a sa e distance rom the excavation.



Ensure that ladders and other means o exit rom thetrench are repositioned so that ladders are never morethan 25 eet away rom any worker in the trench.

Te competent person must remove workers rom the ex-cavation upon any evidence o a situation that could causea cave-in, such as accumulation o water in the trench orprotective system problems. (Te competent person mustalso take actions or other types o hazards such as allingloads or hazardous atmospheres.)

Monitor other types o trench–related hazards that canoccur such as alls rom the edge, rigging hazards, or tox-ic and combustible gases.

Implement and en orce procedures to ensure that work inan unprotected trench is not allowed.

Workers Do not enter an uprotected trench, even or a short task.Inspect the protected trench be ore entering.

Exit the trench and call the competent person i you seeany evidence o problems with a protective system.

Do not assume there will be a warning sign be ore a cavein or that you will have time to move out o the way.

Owners and Clients Insist on trench sa ety practices when you commissionwork [Tompson and annenbaum 1977].

Put trench sa ety into bid documents and contractor qual-i cations.

AcknowledgmentsTis document was developed by .J. Lentz, Susan A anuh,and Matt Gillen, National Institute or Occupational Sa ety and Health.

ReferencesArboleda CA, Abraham DM [2004]. Fatalities in trenching

operations analysis using models o accident causation. JConst Eng Mgmt 130(2):273−280.

BLS [2010]. Census o atal occupational injuries (2000−2009).Washington, D.C. Bureau o Labor Statistics.

CDC [2004]. Occupational atalities during trenching and excavation work United States, 1992–2001. MMWR 53(15):311–314. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5315a2.htm

CFR. Code o Federal regulations. Washington, DC: U.S.Government Printing Ofce, Ofce o the Federal Register.

Deatherage JH, Furches LK, Radcli e M, Schriver WR, Wag-ner JP [2004]. Neglecting sa ety precautions may lead totrenching atalities. Am J Ind Med 45:522−527.

Mulhern B, Lentz J [2008]. Coming out o the trenches…sa ely. Hard Hat News Nov. http://hardhat.com/ME2/Au-diences/dirmod.asp?sid=D8F3EF8405924C33B5F670EB0

A95DCE2&nm=Association+News&type=Publishing&mod=Publications%3A%3AArticle&mid=8F3A7027421841978F18BE895F87F791&id=474F54A087824914BC785DE9FFC92DA9&tier=4

Mulhern B, Lentz J [2009]: renching, Part 2: Steps or em-ployers. Landscape Management, February 4.

NIOSH [2003]. 38 year-old construction laborer dies whentrench walls collapse. http://www.cdc.gov/niosh/ ace/state ace/ky/03KY107.html

NIOSH [2006]. 29-year old male Hispanic landscape laborerdies when nine oot deep trench collapses. http://www.cdc.gov/niosh/ ace/state ace/mi/06mi004.html

OSHA. Excavations: hazard recognition in trenching andshoring. OSHA echnical Manual, Section V, Chapter 2.Washington, DC: U.S. Department o Labor, OccupationalSa ety and Health Administration. http://www.osha.gov/dts/osta/otm/otm_v/otm_v_2.htmlhompson L, annenbaum R [1977]. Responsibility ortrenching excavation and design. J Geotech Eng Division103(4):327−338. http://cedb.asce.org/cgi/wwwdisplay.cgi?7322



For More Information

DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers or Disease Control and PreventionNational Institute or Occupational Sa ety and Health4676 Columbia Parkway Cincinnati, OH 45226–1998

Ofcial BusinessPenalty or Private Use $300

Safer • Healthier • People TMJune 2011

More in ormation about trenching and excavation can be oundon the NIOSH Web site:

http://www.cdc.gov/niosh/topics/trenching/

o receive copies o the NIOSH eld study reports that ormed thebasis o this document or to obtain in ormation about other occu-pational sa ety and health topics, contact NIOSH at

elephone: 1–800–CDC–INFO (1–800–232–4636)Y: 1–888–232–6348 E-mail: cdcin [email protected]

or visit the NIOSH Web site at www.cdc.gov/niosh

For a monthly update on news at NIOSH, subscribe to NIOSH eNewsby visiting www.cdc.gov/niosh/eNews.

Mention o any company or product does not constitute endorse-ment by NIOSH. In addition, citations to Web sites external toNIOSH do not constitute NIOSH endorsement o the sponsoring

organizations or their programs or products. Furthermore, NIOSHis not responsible or the content o these Web sites.

Tis document is in the public domain and may be reely cop-ied or reprinted. NIOSH encourages all readers o the Workplace

Solutions to make them available to all interested employers andworkers.

As part o the Centers or Disease Control and Prevention, NIOSHis the Federal agency responsible or conducting research andmaking recommendations to prevent work-related illness and injuries. All Workplace Solutions are based on research studies

that show how worker exposures to hazardous agents or activitiescan be signi cantly reduced.

Preventing Worker Deaths from Trench Cave-Ins

DHHS (NIOSH) Publication No. 2011—180

Preventing Worker Deaths from Trench Cave-ins

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