The Stringfellow hazardous waste disposal facility, located 50 miles east of Los Angeles, was voluntarily closed in 1972. After groundwater testing results indicated the presence of perchlorate, Kleinfelder was contracted to perform a remedial investigation to characterize the perchlorate source(s) and plume boundaries.

Complex Contamination

Prior to Kleinfelder’s remedial investigation, the perchlorate plume was suspected to extend over a large area, and its full extent was not known. Challenges included possible perchlorate migration via the area’s complex geology as well as potential contamination within an urban community. Perchlorate’s physical characteristics, its interaction with the alluvium, bedrock, and groundwater, and the need for access to private lands owned by concerned community members demanded Kleinfelder’s experience, patience, tenacity, and creativity.

An Intricate Investigation

Kleinfelder’s investigation identified and assessed the nature and extent of contamination, characterized the aquifer system, resulted in development of a comprehensive conceptual site model, and evaluated risks to human health and livestock. Kleinfelder identified both primary and secondary sources of perchlorate, including perchlorate-laden explosives used at an adjacent quarry and widespread historic use of Chilean perchlorate-containing fertilizer. This included advanced isotope techniques to distinguish perchlorate sources.

Project Results

Kleinfelder’s thorough feasibility study included an in-situ bioremediation pilot study, numerical modeling of groundwater flow and contaminant transport, statistical and risk-based development of an ambient perchlorate concentration to evaluate remedial options, and evaluation of green and sustainable remediation. The perchlorate-source evaluation has resulted in a significantly reduced remediation volume.

Project Highlights

• Kleinfelder successfully characterized the perchlorate plume in a complex geological setting while navigating the challenges of working on lands owned by concerned community members.
• Multiple secondary sources of perchlorate were identified in the area that are unrelated to the hazardous waste disposal facility.
• The results of Kleinfelder’s investigation were used to support a feasibility study that evaluated potential remedial options.

Project Details

Location:
Riverside, California

Owner:
California Environmental Protection Agency Department of Toxic Substances Control