Each trench box is 10 feet tall, 20 feet wide, and 20 feet long. Three of these are joined end-to-end to form a trench box 60 feet long. The first set was installed earlier this week, the second set was placed over the first set and installed Thursday. The third set of trench boxes is expected to be installed by Sunday, Aug. 25.

As these trench boxes are installed, the soil inside is removed and the trench box drops down closer to the tunnel break. Once all of the trench boxes are in place and the soil is removed, work inside the tunnel can continue with a much smaller danger of further collapse from soil and rocks above.

At this point it is believed the tunnel walls are still intact at the collapse site and have not caved in. Work in the tunnel has progressed to about 700 feet in from the tunnel entrance.

The tunnel collapse and resulting breach of the main canal bank just upstream on July 17 left more than 100,000 acres of irrigated land without water for more than five weeks in Goshen Irrigation District in Wyoming and Gering-Fort Laramie Irrigation District just across the state line in Nebraska. As of Friday, prospects remained uncertain for restoring water this irrigation season.