The Nevada Occupational Safety and Health Administration (OSHA) has allowed Vegas Tunnel Constructors (VTC) to resume tunneling operations on the Lake Mead Intake No. 3 project. Operations were suspended June 11 following a tragic accident that resulted in the death of a VTC construction worker.
VTC will begin preparatory activities immediately; tunneling may resume within the next few days. Scheduled for completion in mid-2014, the timeline of this project is not expected to be impacted by the delay.
On Monday evening (6/11), a special team from Vegas Tunnel Constructors – the Tunnel Rescue Team -- descended into the tunnel and examined the site of the accident. The VTC team determined the tunnel was safe for entry. After an initial underground investigation, OSHA concurred that VTC could proceed with activities to secure and clean the work area so the joint investigation can move forward.
VTC is currently cleaning the space and preparing to seal the approximate four-inch by two-foot gap where the tunnel ring segment slipped forward allowing pressurized grout to force through. The concrete segment did not fall into the tunnel.
The amount of material that forced through the opening was about one-half of a cubic yard with some 2-inch to 4-inch size rock mixed with grout and mud. No further material has come into the tunnel. One hundred thirty-three (133) of these concrete rings have been successfully put in place by the tunnel boring machine and crews, with a total of nearly 2,500 expected to complete the tunnel. All of the installed segments are stable.
VTC is investigating how the one segment slipped forward and how to prevent such slippage from happening in the future. Tunneling activities will not resume until that determination is complete.
It is with great sadness that the Southern Nevada Water Authority (SNWA) and its contractor, Vegas Tunnel Constructors, report that on Monday, June 11 at approximately 4:30 p.m., an accident occurred at the SNWA Intake No. 3 project area at Lake Mead.
The accident occurred 600 feet below ground in the tunnel area. Three crew members were setting the concrete segments, which make up the 20-foot diameter tunnel. During this process, one of the tunnel segments was jarred loose, and pressurized grout was discharged, striking two of the workers. One of the workers was fatally struck.
This is a difficult time for our organization, the contractor and the crew. At no time were any workers trapped in the tunnel or exposed to toxic gasses. All other workers have been accounted for and are safe above ground. Furthermore, there was no flooding of the tunnel.
SNWA officials are on site and will continue investigating the accident throughout the night. Updates will be provided as needed.
The SNWA, along with OSHA and the contractor, will conduct a full investigation. Construction activities will not resume until the safety of the tunnel has been verified. Our minds, hearts and prayers are with the family of the deceased worker and the family of the injured worker.
Copyright © 2014 Southern Nevada Water Authority