Accident Report Detail

Accident Summary Nr: 201044039 - Employees Are Overcome by Carbon Monoxide in Tunnel

Accident Summary Nr: 201044039 -- Report ID: 0953220 -- Event Date: 12/10/2008
Inspection Nr	Date Opened	SIC	NAICS	Establishment Name
312896111	12/10/2008	1771	238990	Hydro Arch

Abstract: On December 10, 2008, Employees #1 though #5, with Hydro-Arch, were repairing the floor of the south bypass conduit water tunnel located under Lake Las Vegas in Henderson, Nevada. The tunnel was two miles long and seven feet in diameter. They had cleaned the floor of the tunnel and were preparing to pour concrete on the tunnel floor. Two coworkers initially entered the tunnel with a golf cart at approximately 7:45 a.m. to drop off equipment after activating the ventilation fan from outside. Approximately 8:00 a.m., they exited the tunnel to wait for the concrete truck to arrive at the site. Approximately 9:30 a.m., Employees #1 through #5 entered the tunnel with the concrete load. Concrete was carried in eight buggy carts pulled by bobcat. Behind them, the mechanic and Project Superintendent followed on a propane-operated golf cart. Around 10:00 a.m., these employees arrived at the work location and found that the mechanical ventilation fan had been shut down. Several unsuccessful attempts were made to start the fan. The Project Superintendent and foreman decided that work would continue, after measuring the natural air flow using a handheld Mini Thermo-Anemometer by Extech Instrument. At 11:15 a.m., the foreman radioed from inside tunnel that employees were experiencing difficulty breathing, chest pains, and fatigue. The project superintendent sent golf carts and removed all employees from the tunnel about 12:16 p.m. Employees #1 through #5 were treated for asphyxia and carbon monoxide poisoning at University Medical Center (UMC) in Las Vegas and St. Rose De Lima in Henderson. All five employees were treated at UMC with hyper-oxygen therapy. Reports from the employer confirmed that employees' carboxy-hemoglobin concentrations ranged between 12 and 32.

Keywords: CHEST, TUNNEL, ASPHYXIATED, REPAIR, VENTILATION, INHALATION, RESPIRATORY TRACT, CARBOXYHEMOGLOBIN, CARBON MONOXIDE, CONCRETE

Accident Details
End Use		Project Type		Project Cost	Stories	Non-building Height	Fatality
Other heavy construction		Maintenance or repair		$1,000,000 to $5,000,000

Employee Details
Employee #	Inspection Nr	Degree of Injury	Nature of Injury	Occupation	Construction
1	312896111	Non Hospitalized injury	Asphyxia	Concrete and terrazzo finishers	Distance of Fall: feet Worker Height Above Ground/Floor: feet Cause: Pouring concrete floor at grade Fatality Cause: Asphyxiation/inhalation of toxic vapor
2	312896111	Non Hospitalized injury	Asphyxia	Concrete and terrazzo finishers	Distance of Fall: feet Worker Height Above Ground/Floor: feet Cause: Pouring concrete floor at grade Fatality Cause: Asphyxiation/inhalation of toxic vapor
3	312896111	Non Hospitalized injury	Asphyxia	Concrete and terrazzo finishers	Distance of Fall: feet Worker Height Above Ground/Floor: feet Cause: Pouring concrete floor at grade Fatality Cause: Asphyxiation/inhalation of toxic vapor
4	312896111	Non Hospitalized injury	Asphyxia	Concrete and terrazzo finishers	Distance of Fall: feet Worker Height Above Ground/Floor: feet Cause: Pouring concrete floor at grade Fatality Cause: Asphyxiation/inhalation of toxic vapor
5	312896111	Non Hospitalized injury	Asphyxia	Concrete and terrazzo finishers	Distance of Fall: feet Worker Height Above Ground/Floor: feet Cause: Pouring concrete floor at grade Fatality Cause: Asphyxiation/inhalation of toxic vapor

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