River Deep


	Geology could save rivers from chemical dumps

An ancient and dried up riverbed in north-eastern Ohio prevents a pool of chemical waste from infiltrating the Ohio River according to geologists speaking at the Geological Society of America's annual meeting in Denver, Colorado, during November. The finding could preclude the need for costly and hazardous clean up of similar chemical waste sites that carry a risk of spreading, rather than containing, contamination. The discovery also hints at a previously unknown interaction between an underground aquifer and the nearby Ohio River.

On the site of Barium and Chemical Inc. in Steubenville, Ohio, lies an aquifer that contains chemicals such as nitrate and barium that were dumped during a time when this was a legal method of disposal. Since then, the company has completed several million dollars of remediation including extensive soil treatment and removal. Nevertheless, chemical waste lies beneath sand and gravel deposited 10,000 years ago so the company is working with the United States Environmental Protection Agency to determine the best approach to cleaning up the site to ensure the waste never enters the Ohio River, which is a water source for many local towns.


Photos by David Bradley

In 1992, Kevin Svitana an independent hydrology consultant studied the site and found that, unusually, the chemicals in the underground pool were not flowing into the river as geologists would expect. Ever since, Svitana has tried to determine why. Svitana recently reported a partial answer. He believes Ohio River water flowing into old troughs, or paleo-channels, below an ancient course of the river traps the chemical pool within the channels, keeping it well away from the river's current course, almost a mile to the east.

Svitana found that the dry riverbed is linked to the present-day Ohio River through old channels filled with sand and gravel below the surface. Water flows between the buried aquifer and the present-day river in an unusual "see-saw" motion - with the chemical pool caught in-between. Normally, a water source close to a major river will flow directly into the river but never in the opposite direction.

Svitana's advisor at OSU, Larry Krissek, was surprised by the findings as the seesaw shifts very quickly in response to rainfall or a rise in water level in the river. "From my limited experience with groundwater, I knew that groundwater systems respond to surface conditions at timescales of weeks to months, but I didn't realize that the response time could be shortened to hours," he says. Svitana wants to do more computer modeling to understand exactly what makes site capable of trapping the chemicals in this way. If the seesaw effect is not unique to the immediate area, it may help geologists understand other dumping sites along the river. "The question now," asks Svitana, "is will the chemical pool stay in place, so that the company may use a natural attenuation approach to the cleanup?" Svitana adds that "Barium" is, "continuing to evaluate the need for additional remedial actions, the options to be considered will include natural attenuation in addition to other methods."