Further tests are needed, but state geologists say earthquake hazards for Paducah are overstated. USEC will decide soon.
By Joe Walker firstname.lastname@example.org
Seismic conditions are a big factor in a planned December decision by USEC Inc. on where to build a $1.5 billion gas centrifuge plant. By 2010, the new plant will replace the Paducah Gaseous Diffusion Plant, which enriches uranium for nuclear fuel. USEC says Piketon, Ohio, has advantages over Paducah because it already has centrifuge buildings and lacks Paducah's seismic hazards.
Kentucky Geological Survey scientist John Kiefer said he hopes a disagreement with the U.S. Geological Survey over the hazards will eventually be resolved, leading to an easing of stringent building codes that affect economic development.
"It makes a big difference whether the New Madrid Zone runs all the way through Kentucky or ends below Paducah," Kiefer said. "The USGS can't prove that it extends all the way up into southern Illinois, and we can't prove that it doesn't at this point. There's kind of a standoff."
Kiefer's team wants another $500,000 in state money to expand ground testing in the Paducah area. Using $115,000 from the Paducah-based Kentucky Consortium for Energy and Environment, the survey team has upgraded three monitoring stations and added eight.
Kiefer anticipates a meeting among state and federal geologists to try to reach a compromise. David Russ, a USGS executive in Reston, Va., said "the doors are wide open" for dialogue.
A report done last month for the consortium compares seismic design assessments in 1996 for Olmsted Locks and Dam, in 1999 for the enrichment plant and in 2002 for a proposed hazardous waste landfill at the plant. The average peak ground shaking of those three studies and two general studies in the New Madrid Seismic Zone is about a third less than shown by the hazard maps.
The maps suggest worst-case shaking greater than during 1811-12 when the fault produced three of the biggest earthquakes in U.S. history, causing the Mississippi River to flow backward. The studies' average is in the middle of the 1811-12 range of assumed ground motion.
"It is remarkable that five separate investigations performed by different organizations at different times should yield such comparable results," said Dick Schmidt, consortium director. "The lone exception is an estimate by the U.S. Geological Survey that is half again as great as the average."
Schmidt said there is no reason to adopt the federal maps when competent engineering firms conclude that lower hazards may be safely used in designing buildings. His group, part of the state New Economy initiative, is working with Kiefer's group to try to disprove the longtime USGS stance that Paducah is in the northern end of the New Madrid zone.
The maps flow into tougher building codes that make it more difficult and expensive to design and erect structures — such as buildings, bridges and roads — to be earthquake-resistant. Higher seismic hazards also mean higher insurance premiums.
Based on six months of data from new equipment, the state team strengthened its position that the active faults of the zone may not extend into the Purchase.
Russ said he has not reviewed the consortium report. But the maps and resulting building codes were endorsed by the International Building Council, a cross section of scientists and engineers, he said.
"This is not just the USGS standing alone," Russ said. "Our data would indicate the New Madrid Seismic Zone most definitely does continue into western Kentucky."
He said tremors at Olmsted and elsewhere in the region are "strong indication" of the zone. Because the earth is different here than in California, shock waves tend to travel farther, causing more damage, Russ said.
The consortium report was done by retired USEC Inc. engineer Allen Burnett, an expert in safety and seismic design at the plant. It says continued ground monitoring is needed to better understand the zone. Burnett recommended an approach similar to that of the National Association of Home Builders Research Center in developing "reasonable alternatives" for building codes.
The research center study, completed in May for the U.S. Department of Housing and Urban Development, puts maximum ground shaking midway between the average of the various engineering studies and the USGS maps.