For the second time in as many years, contractors working to replace the 1.1-mile-long North Fork Siphon pipeline in the rugged Uinta Mountains of northern Utah are utilizing a cable crane system that’s the first of its kind in the U.S., the project team says.

犹他州中部水库区（CUWCD）的官员说，独特的电缆系统类似于附近滑雪区的椅子，他们正在帮助完成这项为期三年的2800万美元项目。它的环境影响也较小，而成本少于移动材料和设备的传统方法。18luck.cub但是，与COVID相关的旅行限制几乎使该系统于今年夏天扎根。

Officials at CUWCD had been watching the North Fork Siphon in the state’s high Uinta range for several years. The siphon, which moves water between two reservoirs, was completed in 1987 using prestressed concrete cylinder pipe (PCCP), which in ensuing years has accumulated a record of failure in water systems around the world.

“We knew there were problems with this kind of pipe for years,” says Daryl Devey, a project manager for the CUWCD. The agency builds and maintains the system of reservoirs, tunnels and pipelines that deliver water from Utah’s northern mountains to the farms and urban centers in the southern valleys, under the direction of the U.S. Bureau of Reclamation.

High Altitude, High Anxiety

“We had a section of the Jordan Aqueduct [in the southwest corner of Salt Lake Valley] blow out in the mid–’80s, and it caused a lot of problems, and we’d seen failures in systems in other parts of the country. The siphon is under pressure, about 700 psi at some points, so it was a particular concern,” he says.

The North Fork Siphon is part of a system of tunnels and river diversions, including the Upper Stillwater Reservoir at an elevation of 8,176 ft, that delivers an average of 100,000 acre-ft of water annually into Strawberry Reservoir at an elevation of 7,612 ft.

Siphon从Stillwater隧道中携带约285立方英尺（CFS）的水，向杜切斯尼河北叉一分队的山谷地板上下降了700英尺，向下降低了55度的坡度。虹吸管在河下的山谷地板上行驶1,500英尺，并在杜切斯尼（Duchesne）的支流的哈德斯溪（Hades Creek）上游2.5英里处进行了另外30 cfs的水。

The combined 305 cfs of water is then moved 680 ft up a 70-degree grade into the Hades Tunnel, which joins the greater Strawberry Reservoir collection system.

Troy Ovard, Stillwater area manager for the CUWCD, says continued concerns about the integrity of the pipe over the years led to more and more sophisticated inspections. Working with consulting engineers at New Jersey-based Openaka and Pure Technologies, the pipes were scanned using electromagnetic imaging to peer through the concrete and check the condition of the highly tensioned wires inside.

“在2009年，我们进行了第一次电磁测试和检查。它揭示了一些问题区域，我们确实发现了一些断线，但没有太多。” Ovard说。“检查员在2014年回来了，并进行了另一次电磁检查，该检查显示了更多的电线断裂。当时，他们建议更换管道。”

Devey says agency officials knew they needed to act soon, especially given the location of the siphon. “The environmental damage to that area from the pipe blowing out would be catastrophic,” he says. “We couldn’t continue to risk the potential impacts to the environment, the recreation community, our customers and reputation. We have to have a reliable source of water for Strawberry Reservoir.”

Plans for the replacement were developed by AECOM and work got underway in 2018.

来自奥地利的电缆

Brigham City, Utah-based Whitaker Construction, a firm specializing in underground and pipeline infrastructure, submitted a proposal utilizing the cable crane system.

“Some of our guys had seen one [cable crane] working before and felt like it could be a good solution for this project,” says Quinn Hamson, project manager for Whitaker Construction.

Ovard says officials at CUWCD liked Whitaker’s proposal for a number of reasons. “The cable crane has less impact on the environment. Other proposals had plans to cut new switchback roads up the hill. There is also a safety issue because it can get very muddy here, and those roads can get slippery. This is a very steep slope to work on,” Ovard says.

“惠特克向我们展示了电缆起重机也可以加快该过程。它可以将管道移动到他们想要的位置，并且还可以使用它放置回填，CLSM [控制的低强度材料]混凝土，甚至我们还需要钻入岩石，以钻入固定管道的锚固块在斜坡上，”他说。

惠特克（Whitaker）从位于奥地利Sulz的Gantner购买了150万美元的设备。它由两个80英尺高的塔楼和电缆线轴组成，可达到2,000英尺。该系统在顶部使用柴油动力的绞车，将材料向上或向下移动，同时安装了单独的柴油动力绞车电缆抬起并降低材料。该系统最多可携带22吨。替换管为40英尺长的89英寸钢筋增强混凝土。惠特克（Whitaker）于2019年完成了虹吸管的北侧部分。

“This is a much better pipe that we expect to last for 75 to 100 years,” Ovard says.

除了电缆起重机、推土机ted with a winch will be secured at the top of the slope and tethered to a track hoe, which will dig the trench on the hillside before pipework begins.

“这类似于我们去年在山谷的另一侧所做的事情，除了我们没有推土机锚定在顶部。这将使我们有一些灵活性和冗余，”哈姆森说。

The replacement siphon is being constructed 60 ft from and parallel to the existing pipeline, which will remain in operation until the system is fully switched over later this year.

COVID-19电缆扭结

For the first year of work with the cable crane in 2019, a rigging team from Austria came to the site to assemble and help test the system, but this year, project managers got an unwelcome surprise.

Ovard说：“由于Covid-19，来自奥地利的团队不允许进入美国。”

Hamson says he and other Whitaker team members were sent scrambling to find qualified replacements. “We’d had an independent company who did the testing of the crane system for us. They also test ski lifts, and they knew some people in the U.S. and Canada who did this kind of rigging. We were able to get them to come do the setup this year,” Hamson says. “It was a bit of an effort and put us a little behind schedule.”

到7月中旬，起重机系统已经到位并进行了测试。

In addition to the replacement siphon, Ovard says improvements have been made to related components of the system.

“所有的电力和通讯上illwater Dam come through here. The power cable and fiber-optic line run alongside the pipeline and into the tunnel,” he says.

这项工作的范围还包括在Hades转移的新计量系统，并在Duchesne河上替换了一座桥梁，该桥梁容易容易受到树的障碍并限制了鱼的运动。

The project is expected to be complete and in operation by November of this year.