TORRINGTON – A grant designed to help defray the costs of planning the permanent solution to reinforcing Bureau of Reclamation irrigation canal tunnels along the Fort Laramie irrigation ditch in Goshen County has been approved at the state level and is now awaiting review by the Federal Emergency Management Association.
The Pre-Disaster Mitigation Grant has a maximum reward of $200,000. Goshen County Emergency Management Coordinator Shelly Kirchhefer said the Goshen Irrigation District could use those funds to develop the design and plan for the tunnels. One of those tunnels, tunnel No. 2, collapsed on July 17, 2019, and halted the flow of irrigation water to 100,000 acres of farmland in Wyoming and Nebraska.
“All this does is it helps their planning and design,” Kirchhefer said. “If they have an engineer, they’re going to have to look at what is required at the federal level to perform the hardening of the structure.
“The grant funding is basically to help cover those costs and to assist with those costs. It will probably be well over $200,000 for the planning and design for that work they have to do on those tunnels.”
Kirchhefer said the GID’s plan for permanently fixing tunnel No. 2 is to use a technique called permeation grouting. According to sciencedirect.com, permeation grouting is a process used to shore up tunnels in unfavorable geological conditions. It’s used in subsea tunnel projects, as well as situations like the one in Fort Laramie, where the soil is sandy and unstable.
Tunnel No. 1 will also be reinforced.
“They take that permeation anywhere from 10 to 12 feet beyond the grouting,” she said. “That is a chemical solution that solidifies the soil around that. It was really powdery up there. It’s fine and it’s almost like flour. What that solution does is solidify that soil. It turns it into like a sandstone texture.
“That more or less helps to increase the integrity and the compression around that tunnel so it won’t collapse again – or at least that’s the plan. It will at least give it a few more years, and we can go from there.
“It would probably run the length of the tunnel, both of them, and all of the way around.”
Currently, crews from SAK Construction are doing required maintenance on the tunnels to ensure they will last through the 2020 water season.
Kirchhefer said GID should learn if they’ve been awarded the grant by June.
“We started this process in December,” she said. “The state looks at everything that comes in statewide. We put an application in, and that will move forward to FEMA. We probably won’t hear anything until June, which is fine, because they have to complete their maintenance and they’re still working on tunnel No. 2. just like they did for the emergency, temporary work. We’ll go through the water season, and then after this water season we will have 2020 and 2021 to look at the permanent solution.”
The GID and the Gering-Fort Laramie Irrigation District in Nebraska decided on the reinforcement method in November. There has not been a final price tag placed on the permanent fix, as the plans have yet to be finalized.