South Basin Groundwater Remedial Investigation and Feasibility Study
The South Basin Groundwater Remedial Investigation and Feasibility Study focuses on a two-square-mile portion of the groundwater aquifer located under Irvine, Santa Ana and Tustin.
The South Basin is contaminated near the surface with volatile organic compounds (VOCs) left behind from decades-old manufacturing. In this area, the geology is different and the migration rates of the pollutants are a little slower than in the North Basin. One water supply well has been removed from service because contaminants reached elevated levels. OCWD is embarking on a comprehensive plan to control the spread and eventually remove these chemicals that have migrated beyond their original pollution sources and now threaten the deeper aquifers from where drinking water is drawn. Regulatory oversight is provided by the Department of Toxic Substance Control (DTSC) and the Regional Water Quality Control Board (RWQCB). These two state agencies are working closely with OCWD and some cooperative potentially responsible parties to map the occurrence of the contaminants, identify appropriate remedies and implement groundwater cleanup.
South Basin Remedial Investigation & Feasibility Study documents
- Final South Basin Groundwater Protection Project, Operable Unit 2, Feasibility Study (January 27, 2023)
- Draft Feasibility Study, South Basin Groundwater Protection Project, Operable Unit 2 (April 5, 2022)
- Updated Community Involvement Plan (CIP) (August 2021)
- Response to Comments from the SAG on the SRI (January 27, 2021)
- Stakeholder Advisory Group (SAG) Comments on the SRI (August 2020)
- Supplemental Remedial Investigation (SRI) Report (including Appendices A through C) (July 2020)
– SRI Appendix D, part 1
– SRI Appendix D, part 2
– SRI Appendix D, part 3
– SRI Appendix D, part 4
– SRI Appendices E through R - South Basin Remedial Investigation Work Plan (June 25, 2018)
- Human Health Risk Assessment Work Plan (April 26, 2018)
- Additional Groundwater Assessment Field Sampling Plan Addendum 1 (Feb. 5, 2018)
- Applicable or Relevant and Appropriate Requirements (Draft) (October 24, 2017)
- Groundwater Modeling Scope of Work and Cost Estimate (October 2, 2017)
- Data Gap Memo (June 12, 2017)
- Additional Groundwater Assessment Field Sampling Plan and Quality Assurance Project Plan Addendum Version 2.0 (May 9, 2017)
- Community Involvement Plan (CIP) (May 9, 2017) *previous version*
– Stakeholder Letter
– Community Survey - Preliminary Remedial Investigation Report (PRI) Report (October 2015)
– PRI Appendix A – monitoring well logs
– PRI Appendix B – cone penetrometer logs
– PRI Appendix C – source site information
– PRI Appendix D – time series charts
– PRI Appendix E – analytical database
– PRI Appendix F – cone penetrometer pore pressure dissipation logs
– PRI Appendix G – CPT assessment analytical reports
– PRI Appendix H – split sample analytical results
– PRI Appendix I – detailed contour maps - Quality Assurance Project Plan (May 2012)
Updates
- April 2023 update
- April 2023 update (Spanish)
- April 2023 update (Vietnamese)
- January 2023 update
- January 2023 update (Spanish)
- January 2023 update (Vietnamese)
- October 2022 update
- October 2022 update (Spanish)
- October 2022 update (Vietnamese)
- July 2022
- July 2022 (Spanish)
- July 2022 (Vietnamese)
- April 2022
- April 2022 (Spanish)
- April 2022 (Vietnamese)
- January 2022
- January 2022 (Spanish)
- January 2022 (Vietnamese)
- October 2021
- October 2021 (Spanish)
- October 2021 (Vietnamese)
- July 2021
- April 2021
- January 2021
- October 2020
- July 2020
- April 2020
- January 2020
- December 12, 2019
- September 30, 2019
- November 5, 2018 OCWD update
- Dec. 8, 2017 OCWD update
Agenda items
- June 15, 2016 OCWD board of directors meeting
- May 18, 2016 OCWD board of directors meeting and status report
For all items pertaining to the project, please search ourmeetings and agendas page.