Kaiser Aluminum & Chemical Corp. has begun taking water samples at a former aluminum by-product disposal site about 10 miles northeast of downtown Spokane in the Mead area that has been found to contain contaminants.

The site, located near the intersection of Heglar and Kronquist roads, about five miles east of U.S. 2, has been found in earlier studies to contain contaminants. The water testing Kaiser is doing is part of a legal order agreed on by the Foothill Ranch, Calif.-based aluminum producer and the Washington state Department of Ecology.

Ecology says that from 1969 until 1974, Kaiser disposed of nearly 55,000 cubic yards of black dross at the site from its Trentwood rolling mill in Spokane Valley. At the time, the disposal site was operated by Gemini Management Inc., but Kaiser bought the property in 1991, Ecology says.

Black dross contains chemicals and metals Ecology says can be harmful to humans and the environment if they exceed certain levels.

In its current testing, Kaiser will sample surface water, groundwater, and well water near the site, and will prepare a report of the test findings along with an evaluation of possible cleanup options. Ecology expects to seek public comment on the resulting draft remedial investigation documents in the fall of 2011.