Award-winning INEEL probe to help safely monitor hazardous waste sites

10/13/04

Chemicals buried underground don't always sit still. Sometimes, molecules of hazardous waste can travel out of landfills, wandering through soil layers near aquifers. Technology exists to monitor landfill perimeters, but scientists would prefer to keep an eye on contaminants long before they leave the area. Now with a new underground probing system from the Department of Energy's Idaho National Engineering and Environmental Laboratory, scientists can safely and more accurately sample and monitor soil in and below hazardous waste sites.

R&D Magazine declared INEEL's Geologic and Environmental Probe System (GEOPS) to be one of the 100 most significant technological achievements of 2004. Project leader Richard L. Jones, along with team members Tom Clark, Joel Hubbell, Buck Sisson, Jason Casper, Terry Turner, Louis Valenti and Andrew Baumer, will be recognized at the R&D Magazine awards banquet in Chicago on Oct. 14, 2004.

"Winning the R&D 100 award is more than just a good feeling," Jones says. "It should make it easier for us to help people investigate land throughout America and the world that might be contaminated with dangerous chemicals. GEOPS really showcases how science and engineering collaboration can solve difficult environmental problems."

Before INEEL's probing system was developed, geoscientists monitored waste sites by drilling around them -- a task as tough as trying to biopsy a tumor by sampling healthy tissue around it. Now, they can directly measure how hazardous chemicals change over time and tell immediately if they are moving away from the original site. "It's the first technology to be able to go down into contamination without disturbing the downhole conditions," Jones says.

The INEEL team's two-and-a-half-inch-diameter steel GEOPS owes its power to tough materials, unique design, and years of hands-on experience by its creators. "This technology wasn't born from trial and error," Jones says. "We sat down and thought through all the possible problems and things that could go wrong. Then we designed the flaws out from the start."

Faced with a 1960s-era nuclear waste site that they needed to sample directly, Jones and his team set about in 1999 to build new tools for the cleanup job. They wanted to collect data from deep underground without digging up contaminated soil or damaging delicate probe sensors during installation.

The culmination of their five-year project features an innovative sheath for their sensors: a porous, sintered-stainless-steel tube that's capped on one end with a sturdy steel point. Rugged enough to be inserted directly into the earth, this exterior hull was designed to stay underground and house a succession of probe instruments, says INEEL engineer Tom Clark.

Older probing technology wasn't built to be pushed directly into the earth, Clark says. To put fragile sensors underground, workers used a rotary drill to first dig up soil. Then they lowered probes to the bottom of the hole and covered it with loose material such as sand.

But installing GEOPS is almost as clean and simple as pushing a needle into an apple, Clark says. GEOPS' tough tip punctures the surface of the earth and slides easily through without disturbing the soil beneath or damaging its own parts.

GEOPS' hull can take more than 50 g of acceleration and 30 tons of direct push -- the equivalent of surviving a high-speed car crash while having four grown elephants on top of it.

Since GEOPS will withstand forces of a direct installation, workers can bypass risky digging. They can push its casing straight into waste sites, Clark says, or else use a sonic drill that vibrates equipment into the ground without bringing up soil. "It's very safe," he says. "You're isolated from contamination."

Real-world situations demand ruggedness, Jones points out. Cleanup workers don't always know what tough materials lie underground, often because waste was buried decades ago without the benefit of modern record-keeping. GEOPS can penetrate nearly anything -- including hard, compacted dirt and even metal drums. To reach the depth they need, workers string together interlocking GEOPS sections which can reach 300 feet below the surface. During installation, workers lock GEOPS' hollow casing into place in the ground and thread probe sensors through to the bottom. Vacuum seals can pull in vapors and moisture through the casing's porous shell or external ports.

Most important, when researchers have collected data with one sensor, they pull it up and thread another sensor down, Clark says. The universally designed housing will accept a variety of probe sensors, each of which gives different information about underground conditions, such as types of gases trapped in the soil and how dampness changes over time. Since one installation will do the job where many were needed before, workers save time and money, Jones says.

GEOPS also makes it easy to gather extensive, accurate data quickly, Jones says. Having sensors consolidated in one place saves scientists from needing to piece together incomplete information from various locations. And since the probe area is undisturbed by digging, researchers no longer have to wait for soil to settle before collecting measurements.

A system of ports lets workers test and sometimes even fix sensors without hauling equipment to the surface. And off-the-shelf components keep the cost of building and maintaining a GEOPS unit low.

Scientists can use GEOPS in a variety of landfill types, with soil that is either saturated by groundwater or not, making its applications stretch beyond INEEL's mission, Jones notes. About 300,000 waste disposal sites are scattered across the nation, some containing PCBs, corrosives, heavy metals, and radioactive materials. Many of these wastes were buried when scientists thought they were safely isolated in layers of earth above the aquifer.

Potential sites for GEOPS include mine tailings, earthen dams, abandoned and active landfills, nuclear power plants, fuel processing and storage facilities, old industrial sites, and underground storage tanks, Jones says.

The INEEL team has filed a patent application for GEOPS and is currently discussing licensing agreements with industrial manufacturers.

Source: Eurekalert & others

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