Investigation and remediation of chromium and nitrate groundwater contamination: Case study for an industrial facility

During a preliminary site investigation at an industrial facility (Facility) in the California desert, chromium and nitrate groundwater degradation were identified in the area of a formerly operated landfill. No currently used water supplies were identified as being affected. A groundwater extraction system was installed and operated to contain the plumes and remove contaminant mass. Based on data collected during 5 years of groundwater extraction, it was determined that contaminant reduction was not occurring. A review of disposal records for the Facility revealed that potential sources of chromium and nitrate had not been removed. A detailed field investigation of these areas was subsequently completed. The investigation included trenches, several hundred soil borings, and analysis of soil and groundwater samples. The data collected identified the location and extent of the sources of both the nitrate and chromium groundwater degradation. These sources were previously disposed chromium‐bearing kiln bricks in the landfill and undetonated blasting materials in the quarry area at the Facility. The investigation also better defined the geology, hydrology, and contaminant migration behavior. The detailed manner in which the investigation was conducted has provided the basis for the development of a revised corrective action program that coordinates contaminant source removal and ground‐water extraction. The focus of this technical article is threefold. First, the article discusses the site investigation that was conducted and the data which were collected at the Facility. The second focus is the final corrective action plan that was developed. Finally, the cost‐effective nature of the investigation and cleanup is discussed.