This major defense and aerospace manufacturer has operated at the site since 1956, performing aerospace research and manufacturing activities. Since 1992, the client has operated a groundwater extraction system at this site as the approved final remedy under oversight from the area Regional Water Quality Control Board (RWQCB). In 2001, during the performance of a five-year remediation effectiveness evaluation, Cameron-Cole discovered that while the groundwater extraction system was reducing Volatile Organic Compound (VOC) concentrations throughout the majority of the plume, VOC concentrations in a small area of the site were increasing. In response to this finding, Cameron-Cole performed numerous investigations including borehole and monitoring well installation, Cone-Penetrometer-Testing (CPT) and Membrane Interface Probe (MIP) surveys to further characterize the nature and extent of VOCs within the source area. These investigations defined a VOC source area encompassing an approximately 400-foot by 500-foot area to depths of 90 feet Bgs where VOC concentrations exceeded 50,000 micrograms per liter, strongly suggesting the presence of Dense Non-Aqueous Phase Liquid (DNAPL). A remedial alternatives assessment was performed to identify additional remedial measures within the source area. This assessment identified In Situ Bioreactors (ISBRs) as the preferred remedy. In May 2007, a pilot ISBR system was installed consisting of two ISBR treatment wells. Within a year, groundwater VOC concentrations within the source area had decreased by greater than 50% in close proximity to the treatment wells. Based upon these favorable results, an expanded pilot system, designed to treat the entire source area was installed between September 2008 and July 2009. This expanded system was brought online in July 2009 and has since been expanded to 85 treatment wells and is operating successfully with VOCs declining. Installing and operating this system has been significantly less costly than the alternative technologies considered for the site.