lessons learnt- trench collapse
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8/13/2019 Lessons Learnt- Trench Collapse
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November 16, 2009
Lessons Learned Trench CollapseWhat: Trench Collapse Non-Parsons Employee FatalityWhen: October 17, 2009Where: Khaled Al Attar Tower, Dubai, United Arab Emirates
Incident Summary
A welder contractor had to weld apreinsulated carbon steel pipe joint ontoa chilled water pipeline in the groundfloor of a multistory parking facility. AnL-shaped trench had already been dug to4 feet 11 inches, and the chilled watersupply and return pipes were already inplace.
Before adding the last joint, the welderfound the area to be congested andrequested two coworkers to deepen theweld pit and cut a cavity in the face ofthe trench. The weld pit was deepenedusing a jack hammer and a hand shovel.Once the pit was deepened, the welderstarted to weld the pipe joints. However,
the soil in the trench collapsed on thewelder and trapped him.
Immediately, the two coworkers starteddigging to try to release the welder fromthe soil. They summoned assistance,and they were able to dig the welder outof the soil. The onsite first aid personarrived at the scene and administeredemergency assistance while the siteforeman called the emergency services.After 20 minutes, an ambulance arrived, and the welder was transferred to a
hospital. At the hospital, the welder died from his injuries.
Discussion of Activities
Work at the project was suspended until all trench areas were inspected for stabilityand safety. The safety personnel and inspectors had to confirm that trench supportmethods met the site’s approved method statements.
The safety personnel and inspectors identified another inadequate trench shoringarea, and they instructed the contractor to rectify the situation before work wouldbe allowed to proceed.
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Analysis of What Went Wrong
Listed below are the items that went wrong:
The contractor did not follow the approved method statement and apply suitabletrench shoring.
The welder and other contractor’s staff at the site failed to recognize the dangerof digging a cavity and using a jack hammer to deepen the trench, the vibrationfrom which potentially loosened the soil.
The workers present at the site failed to recognize the danger because thetrench wall appeared stable.
Recommendations
Parsons’ recommendations are as follows:
Hold a briefing with Parsons’ site staff and all of the safety personnel to
immediately notify the contractors ’ and clients ’ representatives of work locationswhere there are deficiencies that do not meet safe practices, local regulations,and contract specifications.
The site’s constructio n superintendent and safety personnel must thoroughlyreview contractors’ work locations to ensure that adequate trench shoring is inplace as required by the local regulations and contract specifications.
Suspend work until the contractors have rectified unsafe areas and conditions.
Review the site ’s method statements to ensure that the site’s workers andsupervisors are aware of trench shoring safety requirements.
Work Function: Chilled Water Pipe Installation – Khaled Al Attar Tower
Hazards: Trench collapse, crushing, and suffocation
Originator: Mike Gordon, Project ManagerTelephone: +971 (2) 614-2372Email: [email protected]
Contact: Jeffrey Vance, Safety, Health andEnvironment Director, PILTelephone: +971 (2) 614-2411Email: [email protected]
Reference: Parsons Incident No. 07708
Distribution: All Parsons ’ Programs and Projects