Perchlorate (ClO4-) is a strong oxidizing agent commonly used to manufacture fireworks. A Southern California regulatory agency suspected that illegal disposal of perchlorate had impacted the soil and groundwater of a residential property located in Barstow, California. The owner of the residential property also owned a former pyrotechnics manufacturing company. It was further suspected that perchlorate in groundwater had dispersed and impacted water wells in the region. A groundwater investigation project was conducted within an investigation area which included the properties near the suspected source of perchlorate, and extended 1.5 miles south-southeast. A total of 22 locations were sampled for groundwater to laterally delineate the perchlorate plume to non-detectable concentrations. A pre-feasibility study was prepared to identify perchlorate mitigation alternatives for groundwater, which included a description of a hydraulic containment system and pump-and treat system options.