Hanford Project Using Electricity to Map Underground Leaks

RICHLAND, Wash. (AP) - Taking a page from archaeologists looking
for dinosaur bones, workers at the Hanford nuclear reservation are
testing a technology to map the path of radioactive and chemical
leaks from underground tanks.

In a demonstration project, CH2M Hill Hanford Group is using
electricity in a process called high-resolution resistivity to map
contamination at the federal nuclear reservation's tank farms.

"If we can get a picture of where it may or may not be, we can
go out and take a physical sample," said John Kristofzski, a CH2M
Hill program director.

According to a story published in the Tri-City Herald, the technology has been used to scan for outlines of dinosaurs in rock, but the Hanford project will use it to chart contamination as it travels through soil.

Radioactive and chemical wastes from Cold War weapons plutonium
processing were stored in 149 underground steel tanks at Hanford.

As many as 67 have leaked as much as 1 million gallons of liquid
wastes into the soil. Some contamination has flowed through the
soil and reached the water table.

Historical documents tell Hanford officials what wastes may be
in the soil and where they are. But they need more information to
come up with a plan to clean up the contamination before more of it
reaches the ground water.

Sending electrical current through the ground may provide a map
of contamination without excavation or drilling holes that can
expose workers to hazardous chemicals or radiation, CH2M Hill
officials said.

Working with Columbia Energy and Environmental Services of
Richland and HydroGeophysics of Tucson, Ariz., CH2M Hill is looking
for places in the soil where electricity moves with less resistance.

Soil moistened by waste conducts electrical current better than
dry, uncontaminated soil. In addition, the tank waste often has
heavy chemical salt concentrations that increase conductivity.

In the pilot project, two car batteries will be used to send an
electric current through grids of wires attached to probes. As the
electricity travels between probes farther and farther apart, it
creates a triangular image of soil resistivity as far down as the
ground water.

Those results will be mapped on a computer to come up with a
picture of where waste lies beneath the soil.

The probes create a two-dimensional picture, but probes inserted
down wells already drilled will help to expand the picture to three
dimensions to provide more information about the depth at which
waste lies.

"We want to understand what's out there and where it's
moving," Kristofzski said.