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Tuesday, March 30, 2010

Environment - "Diffuser a fix for Grand Cal discharges?"

With a diffuser, the same amount of pollution goes into the water, but it is diffused or diluted as it is emitted.

Gitte Laasby of the Gary Post-Tribune has a lengthy story today on a pending water permit amendment. Some quotes:

IDEM has accepted the company's request to maintain the same pollution levels in the new permit if the company dilutes it with a diffuser. The Post-Tribune obtained a copy of the permit through a public information request. The permit is up for public comment until April 8. IDEM is not planning a public hearing, but may hold one if requested, according to a public notice.

The Post-Tribune asked IDEM how it could allow a company in 2006 to discharge sulfates in a concentration that's toxic to water critters. IDEM was not able to respond to that, and several other questions, within a day and a half.

Scott Pruitt, a biologist with the U.S. Fish and Wildlife Service in Bloomington, said he was not familiar with the Grace Davison permit but that the critters are often used in toxicity tests as a way to assess water quality.

"Those standards are set by EPA with the help of the state. They look at dilution factor also. As soon as it hits the river, it's not going to be the same (concentration) obviously," he said. "I think your question is, are the standards adequate to protect water quality. There are times when we have questioned that also."

The Grand Calumet River is considered impaired for several reasons, including not having the range or amount of fish that can be expected in similar areas. Researchers found fathead minnows in the river in 1988.

Grace Davison has proposed to maintain the same permit limits for sulfate, but speed up the velocity of the 520,000 gallons of wastewater it discharges per day. The pollution would be diluted by reducing the opening of the existing discharge pipe from 24 to 6 inches. It extends 10 feet into the Grand Calumet and will be tilted upward from the river bottom. Water would flow at less than a foot per second. The mixing zone of water and pollution would extend 10 feet from the edge of the river and ensure that wastewater meets water quality standards at the edge of the zone.

"The proposed new outfall configuration will increase mixing, resulting in a more dilute exposure to the organisms in the river and eliminating the sulfate toxicity," the company wrote in its permit application.

Indiana law allows companies to use a diffuser under certain conditions. Two of them are that it is not likely to jeopardize endangered or threatened species, and that the mixing zone does not extend to drinking water intakes. The nearest intake is in Lake Michigan, and the pollution would be diluted enough going through the Indiana Harbor and Ship Canal that it would not have an impact, the company said.

Posted by Marcia Oddi on March 30, 2010 03:41 PM
Posted to Environment