New technology is providing information on how contaminated ground water from the Hanford nuclear reservation may be entering the Columbia River.

A study for the Department of Energy of where ground water seeps into the river and what contaminants it contains won't be completed until the end of the year. But already there is evidence showing ground water enters the Columbia River in upwellings away from its shores, said Larry Hulstrom, Washington Closure Hanford project lead for the Columbia River investigation.

It's generally been assumed that ground water enters the river in seeps and springs within the first 6 feet of its banks. But some of the ground water may become trapped below a hard layer in the ground and only seeps into deep areas of the river, rather than at its shores.

"We've never had the technology available to determine if it was upwelling further beyond 6 feet," Hulstrom said.

The bottom of the river is covered with cobble and boulders that make it difficult to probe and the swift current makes testing difficult.

Divers attempted to find out more about conditions away from the river bank about 15 years ago.

But when planning started on a comprehensive assessment of the Columbia River to make final decisions on cleanup of the nuclear reservation along the river, officials were reluctant to send divers out again. The cold, swift water made it too hazardous, said John Price, Tri-Party Agreement section manager for the Washington State Department of Ecology.

Instead, Environmental Assessment Services of Richland has worked with Coastal Monitoring Associates of San Diego to adapt a probe that's been used to collect solids from sediment in the ocean rather than water.

"It's not a simple task to remain stationary in river currents flowing at speeds of 3 to 6 feet per second and, at the same time, find a way to drive sensors in the armored riverbed," said Brett Tiller, principal scientist for Environmental Assessment Services.

The advanced Trident probe system that's been developed uses a 500-pound frame outfitted with sensors and sampling tubes that is lowered from a research boat to the bottom of the river. Then, the probe tip is driven into the river bottom.

The probe, which can be used in most portions of the river, was successfully demonstrated in the first phase of a mapping and characterization project last year.

"I think we were all surprised by how well it worked and identified a number of areas of upwelling," Price said.

Without the sampling, information would have to come from computer modeling of ground water entering the river. But the probe should be able to provide a more precise estimate of the risk to river life by finding upwelling ground water and taking measurements of contaminants where fish lay their eggs and fresh water mussels, crayfish and clams live.

"We're just really pleased to have some factual information about what's happening," Price said.

Environmental Assessment Services under a Washington Closure subcontract has completed initial mapping of where potentially contaminated ground water is entering the river near the nuclear reservation's nine defunct plutonium production reactors, the old Hanford townsite and the 300 Area just north of Richland.

The mapping was done during the winter because the probe relies on temperature and conductivity of electricity to determine the water's source. In the winter the river water is a lot colder than the ground water entering it, said John Sands, a DOE engineer. In addition the conductivity varies year-round because ground water has more dissolved solids than river water.

A probe inserted a foot into the cobble at the river bottom and another held a foot above the bottom can provide information to a computer on the research boat on whether temperature and conductivity changes are detected that indicate ground water is entering the river.

Now work is under way to collect samples of upwelling ground water to look for potential contaminants known to be in Hanford ground water, such as strontium, uranium, tritium and chromium. The upwellings could be from ground water from the production portion of Hanford or from the other side of the river.

Samples will be collected in about 240 locations, and then Environmental Assessment Services plans to select 40 locations to do more comprehensive sampling.

The results of the study will be compiled with extensive data on the Columbia River from past studies and from new samples of river water, soil on Hanford islands, sediment from the river and fish to test for evidence of contaminants that might be linked to Hanford.

The comprehensive look at contaminants that may be linked to past production of plutonium at Hanford will help make sure that all necessary cleanup of Hanford along its river corridor is completed. DOE expects to have most of that work finished by 2015.

Monitoring of the river shows it is safe for recreational use, Sands said. Once any contaminated ground water reaches the river, it's quickly diluted.

"This is just stepping down a level of detail," he said.