Bechtel National, the engineering firm trying to erect a treatment plant to turn the worst of Hanford's nuclear waste to glass, has told the government that unexpected problems will dramatically increase construction costs.

Citing everything from new seismic data that will force engineers to recalibrate the plant's earthquake-proofing to the high price of materials, the company reported that one of the world's most-expensive construction projects now will cost substantially more than recent estimates of $5.8 billion.

Officials with the company and the U.S. government repeatedly refused yesterday to disclose precisely what the new price tag would be.

But, as an example of the higher costs, Bechtel spokesman John Britton said one of its new design problems — a change to a series of special pumps housed in tanks constantly bombarded by radiation — will add "a couple hundred million dollars" to the plant's price tag.

"These are all part of the challenges of building a first-of-a-kind nuclear project," Britton said. "This project is the equivalent of two or three nuclear plants. It's a lot different than building a Wal-Mart."

The cost increases also raise new questions about Bechtel's "design-as-you-go" approach to ridding the Eastern Washington desert of the 54-million-gallon stew of radioactive and chemical waste left over from the Hanford nuclear reservation's bomb-making heyday.

Bechtel was hired late in 2000 to build a plant and turn waste now buried in 177 decaying underground tanks into glass logs; the logs then would be shipped to a permanent underground-storage site in another state.

The company was chosen after the Department of Energy (DOE) sacked its initial contractor, British Nuclear Fuels Ltd. (BNFL), which surprised regulators by bumping cost estimates for the plant from $6.9 billion to $15.2 billion.

BNFL had planned to finance and build the plant, and then charge the government for the finished product. That was despite warnings from auditors and some in Congress and critiques from DOE that the concept was a "half-baked idea" and "premeditated stupidity."

Bechtel, on the other hand, offered to design and build at the same time, which could save time and, ultimately, money. It initially estimated costs at $4 billion.

Thus far, design of the plant is about 70 percent complete, and construction is about 35 percent complete.

But in December, new research from the Pacific Northwest National Laboratory indicated that the seismic forces the plant would be subjected to in a major earthquake were substantially higher than once thought.

Dirk Dunning, an Oregon Department of Energy official who serves on a Hanford oversight committee, said federal and company officials told his board in April that it would take months or years to perform the thousands of engineering calculations required for the seismic redesign. The building itself was designed with massive concrete walls, but the pipes, ventilation systems and large tanks used to process radioactive wastes still may be vulnerable in a quake.

In addition, Britton said, higher-than-expected steel costs, strict design standards and the cost of inflation associated with delays all are increasing costs.

"You put it all together, and it's having an impact," he said.

Earlier this month, Bechtel submitted a new proposal to the federal government outlining its estimate of the project's cost. The U.S. Army Corps of Engineers, at the Bush administration's request, reviewed Bechtel's accounting.

"The reports are still under review," said Mike Waldron, a DOE spokesman in Washington, D.C.

The battle over dollars has made Washington state regulators wary; it follows the president's proposal to reduce Hanford's cleanup budget.

"If there are seismic issues with the plant, of course it will drive costs up, not down, so why cut the budget"? asked Washington state Department of Ecology spokeswoman Sheryl Hutchison. "We can keep blinking and wincing over the price of this plant, but it needs to be safe, and it needs to be built, and every time they take a new look, it costs more."

But others, including Tom Carpenter with the watchdog Government Accountability Project, are concerned that cost overruns are a sign that the government is not doing enough to keep tabs on the project.

"We need to treat this waste, and we need to treat it soon, but we've got a very low comfort level that they really know what they're doing," he said.

Times staff reporter Hal Bernton contributed to this report.

Craig Welch: 206-464-2093 or cwelch@seattletimes.com