Slag Disposal Beckwith Property

Contamination has been removed from the Site.  Restricted covenants placed on the property limiting its use due to the presence of waste have been removed.  The Site has been removed from the Hazardous Sites List.  The Consent Decree governing cleanup of the Site has been terminated.  The Site is suitable for unrestricted land use with respect to the contamination for which it became a cleanup site.

Prior to 1984, the Site was undeveloped and covered with vegetation. During redevelopment activities, steel slag was used as fill on the Site between 1984 and 1990. The use of slag as fill at the Site was approved by Ecology and Seattle King County Health.

Steel slag is a waste product of recycling steel scrap by melting it down for reuse. The slag contained lime ash that reacts with water to increase the pH, a measure of alkalinity, to concentration in above regulatory limits.

Cleanup actions were conducted at the Site in 1995-1996 and 2002 to mitigate the discharge of surface water with a pH above the regulatory limit.

In March 2009, pH levels above the regulatory limit were measured in seeps on the north and northwest sides of the Site. Engineering measures installed in 1996 and 2002 to prevent water from coming into contact with the slag proved insufficient in eliminating this interaction. Based on the pH levels measured in seeps leaving the Site, Ecology required further cleanup actions to stop discharge of water with a pH above the regulatory limit draining from the Site into surface water. Cleanup of the site was done by removing the slag from the site and disposing of it at a landfill permitted to accept such waste. The site was backfilled and revegetated.