Fast-Track Slag Site Closure: Fremont, CA

WEST implemented an expedited remedial action plan to address the presence of 50,000 tons of slag waste discovered during the construction of a residential development in Fremont, California. The property was the original site of Kraft Cheese in  the early 1900s. When it was discovered that the native clay at the site made a usable clay product, the founders of Kraft Cheese formed Kraftile. During Kraftile’s operations, the southern portion of the site was mined for clay. The clay mining operations resulted in excavation of large clay pits. The clay pits were backfilled with approximately 50,000 tons of metal slag to depths approximately 30- to 35-feet below the ground surface.  In addition, site use had resulted in the presence of residual fuel oil in shallow soil and groundwater.

WEST conducted site characterization work, prepared a Removal Action Workplan (RAW) including a health based risk assessment, evaluation of lead mobility in groundwater, prepared the CEQA initial study, community relations plan, and obtained approval to begin work from the California

Environmental Protection Agency’s (CalEPA) Department of Toxic Substances Control (DTSC) in less than 60 days. The removal actions included the off-site beneficial reuse of the slag as a road construction material, resulting in significant cost savings. The use of slag containing hazardous concentrations of metals as a road construction material was performed pursuant to the beneficial reuse exemptions in the California Health and Safety Code.  Certification of completion was obtained from DTSC within 100 days of the beginning of the project. The former Kraftile property has been developed into a residential community.