Next round of cleanup starting at former Asarco slag site

Work is about to begin on the next phase of cleanup for the B & L Woodwaste site near the border of Milton and Fife in Pierce County.

Construction starts this month on an underground barrier – or “slurry” wall – to keep contaminated soils and groundwater from leaching out of the former B & L Woodwaste landfill. And in the fall, a groundwater treatment system will begin operating to treat contamination in groundwater in the nearby wetland.

The B & L Woodwaste landfill was used in the 1970s and 1980s to dispose of arsenic-laden slag from Asarco and woodwaste from log sort yards. The slag leached arsenic into the soils and groundwater. The federal Environmental Protection Agency identified the site as a source of arsenic, copper and lead contamination when it added Commencement Bay
and the Tacoma tideflats to its National Priorities List in 1982.

The Washington Department of Ecology (Ecology) has been overseeing the site’s cleanup. Legally responsible parties include Asarco, Murray Pacific, Louisiana Pacific, Executive Bark and Wasser and Winter.

Cleanup actions taken since 1992 include:

– Condensed the original 18-acre landfill into 11 acres.

– Installed a multi-layer “cap” over the landfill to prevent rain from flushing metals and contaminated groundwater out of the landfill.

– Installed groundwater monitoring wells to check for leaking contaminants.

– Conducted a study of the landfill’s potential impacts to nearby wetlands.

This additional work is being done because elevated levels of arsenic were detected in a ditch system around the landfill as well as in the groundwater outside the containment area. A study showed arsenic levels in the nearby wetland were higher than state cleanup levels. It also indicated some waste at the bottom of the landfill was in contact with the water table during winter months.

Ecology has prepared a list of frequently-asked questions to explain more about the next phase of cleanup. It’s available on Ecology’s Web site for the B & L Woodwaste site –
http://www.ecy.wa.gov/programs/tcp/sites/B_L_Woodwaste/B_L_woodwaste_hp.htm .