Dam expansion feels the pinch
October 8, 2005
Construction crews working on the expansion of Elkhead Reservoir east of Craig are pouring about 400 cubic yards of concrete a day. But that’s only half of what they’d like to pour.
The nationwide shortage of cement, a critical ingredient in concrete, has caught up with Northwest Colorado and the Elkhead expansion project scheduled to be completed in a year.
As recently as August, the Portland Cement Association reported that the mountain states, Colorado among them, were not among those experiencing a shortage of cement. About 25 percent of America’s cement supply is imported. In the wake of Hurricane Katrina, supplies tightened further because the port of New Orleans is a key entry point for imported cement.
“There’s a nationwide shortage of cement, and it struck (the Elkhead expansion) last Friday for the first time,” Ray Tenney said. Tenney is the senior water resources engineer for the Colorado River Water Conservation District, and he oversees the $19.5 million construction project at Elkhead.
During peak summer construction, as much as 1,600 cubic yards of concrete were being poured every day. Tenney said he’d like to able to pour about 800 cubic yards of cement every day this month.
“There’s a significant challenge with the work that remains,” Tenney told the Yampa River Basin Partnership board on Sept. 29.
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The shortage of cement is one challenge Elkhead construction crews must overcome. Although the dam that contains Elkhead is earthen, the expansion will require about 14,250 cubic yards of structural concrete. Cement also is an important ingredient in the grout that is being used for a system intended to reduce the amount of water that escapes through the soil at the base of the dam.
“That’s also a supply challenge at the moment,” Tenney said.
Concrete was used to pour the large new spillway at the reservoir. Concrete also is needed for a new control building and a tower that will allow dam employees to release water from different reservoir depths to adjust the temperature and the dissolved oxygen content of discharged water.
Northwest Ready Mix in Craig is the concrete supplier for the reservoir expansion.
Northwest’s Roger Simones said he was surprised when he got the word Sept. 19 that his allotment of cement had been cut by the manufacturer, Holnam Inc., at Devil’s Slide, Utah, just east of Salt Lake City.
“I was told on a Monday we would be cut from 14 loads to five loads a week,” Simones said. “That’s 27 tons a load. We weren’t even supposed to be on allotments. That’s what upset me.”
Simones said he’s been told to expect reduced allotments for at least two more weeks. The cement he mixes with water and gravel to make a batch of concrete is hauled by rail to Rifle, where his trucks pick it up.
Simones said he can’t take on any new customers right now (he delivers concrete to area coal mines as well as to the dam project and building contractors). That could mean that he won’t be able to help people trying to pour foundations for their single-family homes. However, he’ll try to work with contractors who need just a few yards of concrete for a footer that would allow them to build a wall, for example.
Holnam can put out 5,400 tons of cement a day. But that’s not nearly as much as the Portland cement plant in Florence, which produces 80,000 tons a day. The temporary shutdown there ate up inventory and put a dent in the supply statewide. Like Holnam, Portland ships cement by rail to Rifle.
Tenney said construction crews at Elkhead continue to be busy in spite of the reduced cement supply. The excavation of the reservoir involves moving about 107,000 cubic yards of material, and the enlarged embankment calls for about 560,000 cubic yards of material.
Since spring, crews have drilled hundreds of holes 60 feet deep into the bed of the expanded reservoir. It’s part of the process of making it more difficult for stored water to escape the reservoir. Engineers know that the sedimentary rock beneath the reservoir has many layers with gaps between them. A grout made of a mixture of cement and water is pumped into each of the hundreds of holes, where it seeps into the gaps between the layers of rock. Each hole is tested to gauge the effectiveness of the grout. Depending on the results, adjacent holes are drilled, and the process is repeated