Washington Closure Hanford - News Room

Last big liquid waste site near Columbia River cleaned up

Cleanup of the last of Hanford’s major liquid waste sites along the Columbia River is nearly complete. In the last decade, workers have removed 5.6 million tons of contaminated material from 65 liquid waste sites in Hanford’s Columbia River corridor.

“This is a significant achievement in the cleanup of the Hanford Site,” said Richard L. Donahoe, the Field Remediation Closure Project Director for Washington Closure Hanford.

“It finishes an entire class of waste sites, eliminating contamination sources that ultimately threatened the groundwater and the river,” said Donahoe. Washington Closure manages the River Corridor Closure (RCC) Project for the U.S. Department of Energy’s Richland Operations Office.

“Completion of these wastes sites, which contained mobile contaminants close to the river, marks another major step in cleaning up the River Corridor and further drives down the risk associated with Hanford’s legacy,” said Keith Klein, Manager of DOE’s, Richland Operations Office.

Backfill of the 116-N-1 Crib and Trench in the 100-N Area began in mid-April, making it the last of Hanford’s major liquid waste sites in the old plutonium production reactor areas to be cleaned up and backfilled.

Backfilling and revegetating is the final piece of work done at a site after contaminated materials are removed. “The amount of clean soil being moved to fill in the excavated site would cover a football field to the height of a 16-story building,” explained Donahoe.

Even more impressive are the dimensions of another group of liquid waste sites just completed by RCC Project workers in February.

In the last three years, more than one million tons of contaminated materials were removed and disposed from five neighboring sites in Hanford’s K Area, including the massive 116-K-2 Mile-Long Trench, two retention basins, and emergency pond and connecting pipelines.

The 645,000 cubic yards of soil used to fill those excavations is equal in volume to a 37-story skyscraper with a football field-sized footprint.

The cribs and trenches were built to receive chemically and radiologically contaminated water from reactor operations. An estimated 10 billion gallons of contaminated water were released to N Area cribs and trenches between 1963 and 1991. Another billion gallons were released from the two K reactors into the mile-long trench from 1956-1972.

The government built and operated nine plutonium production reactors at Hanford during World War II and the Cold War years. Water from the Columbia River was used to cool the reactors.

As the water passed through the reactor core it oftentimes became contaminated. With the exception of N Reactor, the last plutonium reactor built at Hanford, cooling water was discharged directly into the Columbia River.

When the first eight reactors were operating at full power, about 500,000 gallons per minute were pumped through the reactors and back into the river. Cribs and trenches were built in later years to receive chemically and radiologically contaminated water generated during reactor operations, as well as fuel-manufacturing processes.

Leaks from discharge pipes and retention basins, as well as water discharged to the trenches and cribs, contaminated nearly six million tons of soil with a host of chemical and radioactive materials.

So far, workers have removed nearly 6.5 of the estimated 10 million tons of contaminated material from Hanford’s Columbia River corridor. The total includes material from the liquid waste sites and burial grounds, as well as debris from demolished buildings.

Officials with Hanford's groundwater program said the mile-long trench near the K reactors also was one of the largest sources of chemical contamination in the area, specifically hexavalent chromium. Hanford groundwater is not a source of drinking water and does not impact the overall quality of the Columbia River. However, groundwater contaminated with a soluble form of chromium could affect aquatic life along the shores of the river where some species of fish spawn. Hexavalent chromium poses a potential threat to the health of aquatic life.

"The key to protecting Hanford's groundwater and the Columbia River is cleaning up sources of contamination," said Dick Wilde, Fluor Hanford vice president of Soil and Groundwater Remediation. "This is especially important near the old production reactors, because they are close to the river. After the sources of contamination are cleaned up, our efforts to pump out and treat the groundwater are much more effective."

Wilde said an example can be found near Hanford's H Reactor.  A system to pump out and treat the groundwater has been operating there since 1997 to remove hexavalent chromium.  Environmental restoration crews finished cleaning up a major waste site in 2001, the primary source of chromium contamination. For the first time in decades, the chromium in the groundwater has been reduced to levels approved for drinking water. When the chromium level is lowered to a point that is protective of river life, the pumping system will be placed on standby – possibly as early as this year.

“Cleanup of liquid waste disposal sites along the Columbia, in combination with systems to extract and treat contaminated groundwater, go a long way toward protecting water quality in the river,” said Nick Ceto, Program Manager for the U.S. Environmental Protection Agency's Richland Office.

“Our next challenge is to retrieve solid waste from burial grounds surrounding the reactors. When these two major tasks have been completed the area will be ready for re-use as envisioned in plans for the Hanford Reach National Monument,” Ceto said.

High Resolution Photo

More than a billion gallons of contaminated cooling water from Hanford’s K-East and K-West reactors was dumped into the mile-long trench from 1956-1972. In the last three years, more than one million tons of contaminated material was removed from the trench and other waste sites in the K Area.

High Resolution Photo

The 116-N-1 Crib and Trench is the last of Hanford’s major liquid waste sites near the Columbia River to be cleaned up. Workers have removed 5.6 million tons of contaminated material from 65 waste sites, eliminating a potential threat to the groundwater and the river.