RICHLAND, Wash. — On a desert plateau seven miles from the Columbia River, a massive federal project to clean up a Cold War-era nuclear weapons plant is deeply troubled.
The effort to avoid a future environmental calamity here, at the most polluted site in North America, is a priority of the Energy Department but has foundered because of engineering mistakes and runaway costs. Fifty-three million gallons of radioactive sludge, most of it the texture of ketchup, is stored in scores of underground tanks, some of which have leaked for years.
The Energy Department and its lead contractor Bechtel Corp. are trying to build a sophisticated waste treatment complex -- a small-scale industrial city -- that would transform the sludge into radioactive glass. After spending $4 billion since 1989 and getting rid of three previous contractors, the program has yet to transform a gallon of sludge.
"We have had some world-class technical issues," acknowledged John Eschenberg, the federal manager for construction. "I have made mistakes. Bechtel has made mistakes. If I could relive the last three years, there are things I would do differently."
The project is a long-distance race to empty the leaky tanks and secure the radioactive waste before it becomes a greater menace to the Columbia River. The job is likely to take decades, and the price tag could approach $100 billion.
In January, the Energy Department stopped construction on the two most important parts of the project after it realized it had miscalculated the earthquake risks at the sprawling federal facility, known as the Hanford Site. In recent weeks, it put off any resumption of construction until after October 2007. At best, the plant would be finished in 2019.
What remains uncertain is whether the plant's remarkably complex technology will work as planned. Shortly after construction was halted, a team of experts delivered a sobering report that warned of a large number of other potential technical issues that could undermine the plant's operation.
In addition, a long list of major safety problems has been discovered -- though these problems are fixable, construction managers say. They include the potential for explosive hydrogen gas to build up inside the plant's pipes; concerns that the steel frame had inadequate fireproofing; and the discovery of faulty welds in tanks designed to hold dangerous waste.
The cumulative effect of all the problems and challenges has been staggering.