To view this video, you need to download the latest version Flash Player.
John Hollenhorst reporting
Let's call it "The Great Wall of Utah." The federal government has awarded a contract to build what may be one of the biggest walls ever in Utah, and one of the biggest of its type in the country. The thing is, once it's built, you'll never see it.
Imagine a wall 5 feet thick, up to 70 feet high and 5 miles long. Crews are going to start building it next month at Willard Bay to prevent a tragedy. It will be inside Utah's biggest dam, undoubtedly "the biggest dam wall" you'll never see.
Willard Bay is one of Utah's most popular recreation lakes, but the water level has deliberately been kept exceptionally low for the last year and a half. That's because of an alarming problem that cropped up under the 14-mile-long dam that nearly surrounds the reservoir.
Seeping water was oozing out of the ground on the dry side of the dam. A cross section of the earthen dam shows why: Water was flowing where it wasn't supposed to be, under the dam, threatening to wash away critical soils. "And cause a void underneath the dam that potentially could make the dam slump," said Tage Flint, general manager for the Weber Basin Water Conservancy District.
Now the fix is in, at least on paper, an astonishing plan to cut off the seeping water. "It's going to be a huge structure inside of the existing dam," Flint said.
The plan is to use a track-hoe machine that will have a huge arm on it, long enough that it can dig 70 feet straight down into the dam. Crews will cut a deep trench in the dam and fill it with concrete and clay. It will extend under the dam into an impermeable natural layer of clay.
The resulting "cutoff wall" will shore up 5 miles of the 14-mile-long dam. "Once it's in place, it will essentially be a concrete-clay wall that will be 5 feet wide, 70 feet deep and 5 miles long," Flint explained.
On a smaller scale, similar cutoff walls have been used to fix dams around the world. "So we know that it will work. The difference here is that it will be probably for a longer length than we've ever seen," Flint said.
The cost is maybe less than you'd expect for such a big project, about $17 million. They're getting a good deal because of a big slump in the construction industry.
If all goes according to plan, Willard Bay should be back to normal levels in 2010.
E-mail: jhollenhorst@ksl.com
News |
Weather
Traffic |
TV
Sports
Opinion |
Radio |
Classifieds
Announcements
Events
Movies |
Advertise with KSL
Other Resources
Wireless
Legal
Sister Sites
|