Creating New Habitat As Part of Hazardous Waste Cleanup at Asarco

Smelter before the stack was removed. Photo from WDNR.

From 1890 to 1985, Asarco (the American Smelting and Refining Company) operated one of the largest North American smelters in Tacoma, Washington, on the southwest shore of Commencement Bay, an embayment of southern Puget Sound.

Asarco shipped copper ore from Alaska and other locations to the Tacoma smelter. The copper ore was heated in the smelter until it melted and the liquid copper could be separated from the other minerals. The leftover molten material cooled to form a brittle solid slag that included harmful metals such as arsenic and lead. The rocky slag was dumped along the Commencement Bay shoreline, covering sandy beaches to depths of 30 feet, and into deeper waters to create a 23-acre breakwater peninsula. Asarco estimates that 15 million tons of slag is on the site.

Note how the nearby slag peninsula forms a breakwater that protects a small boat basin.

As the Slag Cooled

As the slag cooled, the harmful metals were bound-up in the rock-like matrix. However, the slag can be broken by waves and storms, creating new surfaces where water can slowly dissolve the harmful metals. Metals released from the slag can poison marine plants and animals. The site is being cleaned up under the federal Superfund program. The U.S. Environmental Protection Agency (EPA) is the lead agency, and current work is directed by Kevin Rochlin of the EPA regional office in Seattle. The NOAA Office of Response and Restoration (ORR) Assessment and Restoration Division (ARD) program has advised EPA for more than a decade on sampling plans, site investigations, ecological risk assessments, and cleanup planning for this Superfund site. Part of EPA's selected remedy for the site includes armoring the shoreline to prevent further loss of slag material into the bay. NOAA worked with EPA and Asarco to build a habitat component into the shoreline cleanup plan to accelerate coastal habitat recovery.

Photo galleries

Asarco Site Tour View this gallery of images from an August 2000 tour of the site (11 images)