Regional map
Perchlorate Detections in Groundwater

Key Issues

  • Responsibility for costs involved in characterizing and remediating perchlorate contamination
  • Significance of ongoing managed aquifer recharge operations in diluting perchlorate concentrations


  • Provision of credible technical support to attorneys
  • Expert assessment of site remedial activities
  • Critical review of numerical modeling

Perchlorate Litigation, Llagas Subbasin

Santa Clara County, California

Santa Clara Valley Water District actively addressed perchlorate contamination in the Llagas Subbasin. Seeking reimbursement for its costs, the District retained Todd to provide expert technical support in documenting the benefits of its actions.

Todd Groundwater (then operating as Todd Engineers) was retained by Bingham McCutchen LLP (Bingham) to provide expert witness support in a litigation filed by Santa Clara Valley Water District (District) against Olin Corporation (Olin).

The District, the primary water resources agency in Santa Clara County, provides active groundwater management for the Llagas Groundwater Subbasin, including monitoring of groundwater levels and quality, and managed recharge of local and imported surface water. The District also strives to protect groundwater from contamination and to improve groundwater quality.

Olin historically operated a flare manufacturing facility located in Morgan Hill in the Llagas Subbasin. The Site is the source of an approximately 10-mile long groundwater perchlorate contamination plume. In response to the perchlorate contamination, the District provided detailed technical assessments and recommendations to the Central Coast Regional Water Quality Control Board (CCRWQCB), the Site regulatory agency, to encourage aggressive and effective perchlorate characterization and remediation. The District sampled almost 1,000 private wells; handled thousands of public inquires; conducted and supported public information meetings; and supplied data to Olin, the CCRWQCB, and the public. The District also initiated a program of free well testing and bottled water service in January 2003. The District sought reimbursement from Olin for cost of these actions.

As part of its core mission, the District implements various operations to recharge local surface water from the Districtís reservoirs as well as water imported by the District to increase long-term water supply reliability. These recharge operations in the Llagas Subbasin have benefitted Olin through dilution of the perchlorate plume and associated reduction in perchlorate concentrations. As a result, the District requested reimbursement for costs associated with its recharge operations in the Llagas Subbasin.

Sally McCraven, Principal Hydrogeologist, and Dan Craig, Senior Hydrogeologist/Modeler with Todd provided expert witness support to Bingham for the litigation. Their work included review of Site investigation reports, data analysis, assessment of modeling performed by Olin, and preparation of expert and expert rebuttal reports. The case was settled out of court prior to trial.