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Occupational Safety and Health Administration OSHA

Accident Report Detail

Accident: 200712529 - Two Employees Asphyxiated By Methane Gas In Manhole Contamin

Accident: 200712529 -- Report ID: 0636900 -- Event Date: 05/13/2005
InspectionOpen DateSICEstablishment Name
30864654605/13/20051623Lonestar Underground, Inc.

At approximately 11:00 a.m. on May 13, 2005, Employees #1 and #2 were found at the bottom of an SBC manhole. It was one of two between which their employer was clearing the conduit for a utility line SBC used for communications only. According to the employer, the manhole cover had been left off the night before. In the morning, a blower was used to ventilate the manhole for about 20 minutes; it was then monitored and no problems were observed. The two employees entered the first manhole while using continuous ventilation, and they used a pump to remove water from the bottom. After completing the work, they left the first manhole and went east (toward Colin County) to the next manhole. The foreman told Employees #1 and #2 to come to the second manhole and watch for the ratline (a paper wrapped in duct tape, attached to nylon twine), but not to enter it. From the first manhole, after it was ventilated and tested, coworkers ran a ratline through one of the conduit lines and Employees #1 and #2 acknowledged, via phone because the slope precluded visual contact, that the ratline had come through. A second ratline was run, and the Employees #1 and #2 acknowledged that it too had come through. After a third line was run, there was no response. The foreman went to check and found the two employees in the bottom of the manhole. Before doing a re-evacuation, he first entered the manhole to help, but then realized he needed to get out and call for help. The Colony Fire Department responded and started rescue/retrieval operations, but both employees had died. According to the medical examiner, the cause of death was asphyxia from methane gas. At 2:00 p.m., the CSHO tested for oxygen deficiency, carbon monoxide, and percentage of lower explosive level and found no problems. Possible sources of gas were gas pipelines and sewer lines in the vicinity, as well as possible decomposition products from the bottom of the manhole and the utility line.

Keywords: asphyxiated, ventilation, work rules, construction, inhalation, natural gas, chemical vapor, manhole, chemical
Accident Details
End Use Proj Type Proj Cost Stories NonBldgHt Fatality
Powerline, transmission line New project or new addition $1,000,000 to $5,000,000 X

Employee Details
Employee # Inspection Age Sex Degree Nature Occupation Construction
1 308646546 Fatality Asphyxia Occupation not reported FallDist:
FallHt:
Cause: Installing equipment (HVAC and other)
FatCause: Asphyxiation/inhalation of toxic vapor
2 308646546 Fatality Asphyxia Occupation not reported FallDist:
FallHt:
Cause: Installing equipment (HVAC and other)
FatCause: Asphyxiation/inhalation of toxic vapor

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