Integrity Work at 16 Below Zero (Includes Video Content)
The winter of 2013-2014 still does not feel over, and it is March 26. It was 16 degrees this morning. Despite winter conditions integrity work on pipelines is not suspended. In January with deep snow on the ground and temperatures plummeting to -16 our project managers and crews were challenged to weld a sleeve on an anomaly in the middle of the Little Calumet River. The water was not deep but in below zero temperatures any amount of water makes conditions worse. An additional challenge came in the form of a wetland area around the immediate dig site. Watch a short, time lapse, video on our website.
A plan was developed that involved snow clearing, wetland protection, crew protection and warming areas, and a cofferdam to control the water. A job site safety analysis was performed. All above and below ground hazards were identified and marked. A site layout was designed that included routing paths for power cables, pump placement and dam placement. Next a bottom survey and bottom sediment sample was carried out to verify that the dam placement would work.
After placing mats to protect the wetland and setting up the equipment and warming trailer the work began. On the first draw down the dam appeared solid and we were ready to place the trench box when the dam failed and flooded. We then got to work resetting the dam and creating a stronger seal and on the second attempt we had the water controlled, set the trench box, performed the welding, NDT and coating. The temperatures were solidly below zero and it was a challenge to keep the pumps from freezing and to keep the filter bags flowing.
Crew members were in the water either in waders or full dry suits. Keeping an eye on their condition and allowing time for warm up was important to maintaining worker safety. Moving chunks of ice 6 to 8 inches thick caused constantly shifting pinch points. Operators had to maneuver in a very confined area and were constrained by overhead power lines, wetlands and the stream boundaries.
Our welders did a superb job with the sleeve fitting and welding. The use of DensoTherm tape allowed us to achieve a good coating and immediately backfill and turn off the pumps.
The shoring and dam materials came out a lot faster than they went in. Our customer was pleased with the outcome and the DNR was happy that we did not harm to the wetland since it was frozen solid the entire time.
This project is an example of a rapid, but thoughtful, response to a pipeline anomaly that required immediate attention. Thanks to the crews for acting as a team and working safely.