WorldWide Drilling Resource

19 Line 5 Mackinac Tunnel Project Compiled by Editorial Staff, WorldWide Drilling Resource ® Some of the most interesting arti- cles we present come from subscriber calls to WorldWide Drilling Resource, Inc. Their concern(s) about something that is happening, or should be happen- ing, puts us on the hunt for more infor- mation. Such was the tip on the Mackinac Straits situation, called in by Stan Kemp. This is quite interesting, and we are glad to see a potentially dangerous situation being addressed. Kemp reported a seg- ment of Line 5 pipeline had been dam- aged by a large freighter’s anchor, which caught on a pipeline support, denting the pipeline coating in several places. The good news is tunnelling to replace this vital segment of Michigan’s Line 5 will start soon, reducing the risk of a release of crude oil and natural gas liquids into the Mackinac Straits almost to zero. Enbridge is engineering the $500 million Great Lakes Tunnel Project. The final design and construction plans for the four-mile tunnel were made following a 2019 geotechnical program to sample rocks and sediment. Preliminary plans are to construct a tunnel with an internal diameter between 18 and 21 feet bored through rock at depths of as much as 100 feet below the lake bed. Over two million work hours will be required to complete the tunnel. Staging areas on both the north and south shores will be established. A tunnel boring machine (TBM) 500-feet long is pro- jected to take about two years to bore the four-mile tunnel. A large portal on the south shore will be the entry point. The TBM’s cutter head, rotating and breaking up ground, is in front of the circular shield. Behind the shield, concrete segments form a cir- cular lining to seal the tunnel. Circling, the TBM bores forward, builds a concrete lining ring, pushes forward, stops to build another ring, and repeats the process. Drilling through limestone, shale, and other rock, the TBM will progress 40 feet per day on average and run five days per week. Equipped with sensors to provide data on performance, the TBM will operate like a submarine, sealed off from surrounding ground and water. Saturation divers will perform inspections and maintenance at the TBM’s head. On the north shore, a vertical shaft will allow for retrieving and dismantling the TBM after excavation is complete. After the tunnel is bored and sealed, coated and welded pipe segments will be pushed along a roller system bolted along the tunnel wall. Finally, the Great Lakes Tunnel will be equipped with drainage, leak detection equipment, elec- tronic communications, and a ventilation system allowing access for mainte- nance crews. Then the dual pipelines which it replaces will be permanently deactivated. Enbridge plans to place the new Line 5 segment under the Mackinac Straits into service in 2024. Publisher’s Note - If you know of something in the drilling industry that would interest other readers, please call 850-547-0102. DIR Tunnel boring machine (TBM). Photo courtesy of Enbridge. Alberta Water Well Drilling Association Convention / Trade Show March 25-27 Look for the show theme here in the February issue. Cambridge Hotel & Conference Centre Red Deer, AB, Canada Thursday 25th 8 p.m. - Wine & Cheese Welcome Friday 26th 8:30 a.m. - Continental Breakfast & Trade Show Opens Noon - 2:00 p.m. - Luncheon (guest speaker to be announced), followed by awards and presentations 4:00 - 5:30 p.m. - Annual Meeting First Session 7:00 - 11:00 p.m. - TRADE SHOW  Silent Auction Friday evening - Saturday 1:30 p.m. Contact Sheena Larson for more info 780-386-2335 or e-mail 2021 Saturday 27th 9:00 -10:30 a.m. - Technical Session 10:30 p.m. - 2:30 p.m. - TRADE SHOW 2:30 - 4:30 p.m. - Annual Meeting Second Session WorldWide Drilling Resource ® JANUARY 2021