Remedial Investigation and Strategy, South Archibald VOC Plume in Groundwater, Chino Basin, California

EKI assisted a group of private companies, a collection of municipalities, water agencies, and several military branches that received draft Cleanup and Abatement Orders from the Santa Ana Regional Water Quality Control Board (RWQCB) to address groundwater within the Chino Basin contaminated with total dissolved solids (TDS), nitrate, and perchlorate, and volatile organic compounds (VOCs). EKI served on a technical subcommittee that consisted of company representatives from the private companies, municipalities, water agencies, and military. EKI prepared the remedial investigation report and devised the remedies presented in the feasibility study for the South Archibald VOC Plume in groundwater that simultaneously fulfilled the objective of the municipalities and water agencies to increase local water supplies.

As an alternative to a costly new treatment system proposed by another engineering consulting firm, EKI advocated that extracted groundwater containing TCE and perchlorate be conveyed to the existing Chino Basin Desalter Authority (CDA) Desalter II that is equipped with ion exchange vessels and reverse osmosis (RO) membrane units to remove TDS and nitrate from groundwater, which are legacies of dairies formerly present throughout the region. To adjust the pH of water from the RO membranes so it is suitable for potable supply distribution, the RO permeate is passed through decarbonation towers to remove dissolved carbon dioxide gas. The decarbonation towers are essentially air strippers. EKI determined the towers could also remove TCE without the need for constructing and operating wellhead treatment facilities if a dedicated pipeline was built to convey groundwater from the extraction wells to CDA Desalter II. Collaboration amongst the stakeholders promoted opportunities for the municipalities and water agencies to pursue and secure state and federal funding to financially support the implementation of the project. Installation of the extraction wells and dedicated pipeline was funded by Proposition 1 Groundwater Grant Funding Agreement No. D1712507 and Title XVI grants from the United States Bureau of Reclamation. Construction was completed in 2022. The project facilitates pumping and treatment of additional groundwater to provide much needed water for drought plagued California.

Outcome

Through EKI’s support, a settlement was reached with the RWQCB that relieved our clients of ongoing financial obligations associated with the South Archibald VOC Plume.