Freestone Environmental Services is developing a better way to monitor chromium contamination in groundwater after seeing the need as a Hanford nuclear reservation subcontractor.
The Richland business has been awarded a $1 million Small Business Innovation Research Grant to do real-time monitoring of the contaminant. The grant program supports the development of new technologies critical for Department of Energy projects.
Dan Tyler, Freestone president, is optimistic that a better chromium monitor also would have worldwide applications.
At Hanford, sodium dichromate was brought in by rail tanker cars to be added to reactor cooling water to prevent corrosion. The chemical dissolves in water to hexavalent chromium, which is a carcinogen in humans. It is toxic to young salmon and other aquatic life, even in small amounts that meet drinking water standards.
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The sodium dichromate spilled and leaked into the ground at Hanford during the years that reactors were operating to produce plutonium for the nation's weapons program. Cooling water with the chemical also was discharged to the ground.
That left five square miles of contamined groundwater near the Columbia River at Hanford. DOE is cleaning up the chromium with a series of plants that use wells to pump contaminated water out of the ground. The water is then cleaned and injected back into the ground.
But the contaminated groundwater is not static. Activity at upriver dams causes the river to rise. Seasonal changes also affect the groundwater along the river.
Hanford workers track the contamination by drawing individual samples from monitoring wells by hand and then having the samples analyzed, according to Freestone. It has served as a subcontractor under CH2M Hill Plateau Remediation Co. and its predecessor, Fluor Hanford, supporting groundwater characterization work.
The current method is expensive and slow, Tyler said. But Freestone is developing a sensor that can be left in a monitoring well.
"It can see what is happening at any given instance instead of taking a sample and weeks later finding out what the result is," Tyler said.
Its sensor, invented by Freestone senior geochemist Steve Hall, sends a beam of near-ultraviolet light through contaminated water. Some of the light is absorbed by chromate ions, weakening the beam. By measuring the change in intensity, the level of chromium contamination is revealed.
The sensor also has the capability to correct readings to account for particles in the water that scatter the light.
The results can be transmitted by radio signals back to a water treatment plant to provide guidance on which well to pump.
"We view it as a way to ultimately reduce cost while getting optimum cleanup," Tyler said.
A $150,000 Small Business Innovation Research Grant in 2012 to Freestone paid for proof of the concept.
Now Freestone will use the $1 million grant for two years to demonstrate the performance of a sensor prototype, in part by using it in Hanford monitoring wells.
Its long-term goal is to commercialize the sensor for use beyond DOE as some states consider stricter chromium groundwater standards. Hexavalent chromium is used for stainless steel and textile dye production, wood preservation and leather tanning.
"Worldwide it is a big issue," Tyler said.