Update of North and South Basin Groundwater Cleanup
The Orange County Water District (OCWD; the District) manages and protects the Orange County Groundwater Basin that underlies north and central Orange County, from which 19 cities and water agencies draw their water supply. OCWD implements a proactive groundwater and surface water monitoring program to protect the quality of the Orange County Groundwater Basin and ensure the water it provides meets or exceeds state and federal drinking water standards.
Industrial chemicals have impacted areas in the northern and southern parts of the groundwater basin; North Basin (near Fullerton, Anaheim and Placentia) and South Basin (near Santa Ana, Tustin and Irvine). OCWD is proactively seeking ways to clean up the pollution in a united effort with local and national regulatory agencies.
Below is an update on activities in and around the North and South Basin sites. OCWD will continue to update stakeholders as the need arises.
- The North Basin Site is expected to be listed by the U.S. Environmental Protection Agency (EPA) as a National Priorities List (NPL or Superfund) site in Spring 2020.
- EPA is in the process of responding to public comments regarding the proposed NPL listing and will post its responses prior to listing the site.
- OCWD’s draft remedial investigation (RI) report will be submitted to regulatory agencies for review at the end of March 2020. The RI includes installing and sampling monitoring wells to characterize the extent and depth of groundwater contamination, updating contaminant plume maps, preparing a Baseline Human Health Risk Assessment, and refining a groundwater model that will be used to develop interim remedial alternatives to contain areas with elevated contaminant concentrations.
- OCWD has begun the feasibility study (FS) for an interim remedy. The FS includes identifying and screening remedial technologies as well as developing, screening and evaluating cost-effective alternatives to remediate the groundwater contamination.
- EPA is currently working on a North Basin community involvement plan (CIP). Interviews with community members took place Jan. 28-30 and Feb. 18-20. The CIP also includes activities to inform and solicit input from the community and is expected to be finalized by June 2020.
- OCWD is nearing completion of the RI phase of the remedial investigation and feasibility study. In December 2019, OCWD submitted a revised draft RI report to the regulatory agencies that incorporated regulators’ technical review comments from a prior draft report. The RI phase is expected to be completed by April 2020.
- OCWD performed an assessment of the risk to human health and the environment associated with contaminated groundwater in the South Basin area. A draft human health and ecological risk assessment (HHERA) report was submitted to the regulatory agencies in October 2019 and technical comments were provided to OCWD. The District is preparing responses to those comments in a revised HHERA report that is anticipated to be completed by April 2020.
- OCWD has initiated the FS phase of the South Basin project by developing a computer groundwater flow model which will be used to evaluate potential remedial alternatives to address groundwater contamination that has migrated away from source locations and is not being addressed. Potential implementation of a selected remedy, or remedies, will be consistent with and complementary toward existing active remediation systems operated by other parties.
For additional information, please contact Roy Herndon, chief hydrogeologist at email@example.com or (714) 378-3260.
- EPA North Basin website: http://www.epa.gov/superfund/orange-county-north-basin
- North Basin general information: /what-we-do/water-quality/groundwater-cleanup/north-basin/
- South Basin general information: /what-we-do/water-quality/groundwater-cleanup/south-basin/