The approximately 5.6 square mile SBGPP area (Project Area) is in the south-central part of the roughly 350-square mile Orange County Groundwater Basin (Basin) in Orange County, California. The Project Area is within the southeastern portion of the city of Santa Ana, the western portion of the city of Irvine, and the southwestern portion of the city of Tustin (Figure 1). Groundwater contamination from industrial and manufacturing activities, underground storage tank leaks, waste disposal practices, and other sources occurs in the Project Area, primarily in the Shallow Aquifer System of the Basin, which occurs from ground surface to a depth of approximately 200 feet. The Shallow Aquifer System is designated as a municipal beneficial use supply source by the Santa Ana Regional Water Quality Control Board (RWQCB 2019 – Water Quality Control Plan Santa Ana River Basin, as amended) and is a valuable environmental resource worthy of protection from contamination. In addition, in some areas of the Basin where densely spaced industrial properties have been present for decades and have released chemicals to the groundwater, the groundwater contamination from these sites has migrated off the individual sites and merged to form extensive “commingled plumes” of contamination. In these cases, including the Project Area, the uncontrolled contaminant plumes have not been comprehensively contained or treated by responsible parties and, therefore, threaten the drinking water supply.
