Work has begun to collect about 1,200 samples to check for possible contaminants, a process that will help drive the final decisions on cleaning up Hanford along the Columbia River.

Workers are collecting 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 the past production of plutonium at Hanford for the nation's nuclear weapons program.

"After the sampling we'll know where and what the contaminants are and who or what might be exposed to them," said Jamie Zeisloft, the Department of Energy project lead.

The data collected from the new sampling along 120 miles of the river will be combined with extensive data from sampling done for decades on the Columbia to produce a more complete estimate of the potential health risks to people, animals and plants.

The results could lead to changes in cleanup plans to control or reduce the risk of exposure. Results will be used to help make the final cleanup decisions for Hanford land along the river, where cleanup is expected to largely be completed by 2015.

"We think there are important data gaps to fill," said Laura Buelow, an Environmental Protection Agency scientist. EPA and the Washington Department of Ecology regulate Hanford.

A 2006 review of data requested by Hanford regulators looked at sampling results from Grand Coulee Dam to Astoria, Ore., said John Price, environmental restoration project manager for the Washington State Department of Ecology.

It did not find contaminants of concern originating from Hanford in areas accessed by the public now, but did find some areas where more information could be helpful, particularly downstream from Richland, Price said.

"It's fine for any uses allowed in the (Hanford Reach National) Monument now," Price said. "There is no reason for the public to be concerned."

Sampling and analysis has been done by contractors for DOE and independently by the Washington Department of Health. The river divides the monument from the former production portion of Hanford, which is off limits to the public.

The plan for the additional sampling focuses on areas where Hanford contaminants most likely might be present. That primarily includes locations where sediments have built up on the river bottoms downstream from Hanford's nine production reactors and behind the first downstream dam, islands and areas where contaminated ground water might well up into the river bottom.

Areas such as shoreline parks and boat launches where the public is most likely to use the river for recreation also will be targeted.

To help understand whether contaminants are linked to Hanford or not, sampling also is planned upriver from Hanford and at irrigation returns and locations where other rivers enter the Columbia River.

Most sediment samples will be collected in the upper 4 inches of the river bottom. But a number of deeper core samples also will be taken.

"It's digging big sediment cores that will give us a timeline," Buelow said.

That includes samples that might have built up at the Bonneville Dam, the only dam downstream when Hanford production began, and at McNary Dam, which was completed before Hanford's highest production years.

DOE contractor Washington Closure Hanford has hired Integral Consulting Inc. of Mercer Island to collect the water, soil and sediment samples.

It will hire a second subcontractor to collect fish samples from above Wanapum Dam downstream to McNary. Samples collected from above the Priest Rapids and Wanapum Dam will provide information about background conditions, and samples from downstream of Priest Rapids Dam will be used to characterize possible Hanford contaminants.

Fish are being sampled primarily to estimate the potential health hazards to people eating them, but also to assess risks to the fish population. Samples will be taken from fish species that are popular for sport fishing or are part of the Indian diet. They will include whitefish, sucker, walleye, carp, bass and sturgeon.

Salmon will not be sampled because they do not spend much time in the Hanford Reach during their lifetimes.

The study will look at human exposure to possible contaminants based on scenarios that range from Indians who eat Columbia River fish daily to children who swim in the Columbia River and play on the beaches.

The sampling began this month and will be completed by September 2009.

"We need the results to this study to make good cleanup decisions," Buelow said.

Final decisions on cleanup along the Columbia River, called records of decision, are expected to start being made in 2011.