Groundwater-related Litigation

GEOSCIENCE was retained by the City of El Cajon to provide expert witness services regarding the issue of liability related to damages sustained during a major landslide. In February 2005, El Cajon, a community of some 100,00 people located in San Diego County, California, suffered what became known as the Tyrone Street Landslide. Extensive damage was done to homes in the Fletcher Hills neighborhood of the City, and as a result, a group of homeowners filed a $15 million lawsuit against the City and the local water district on a variety of legal claims.


GEOSCIENCE was called in to provide a thorough hydrologic investigation in connection with the lawsuit. After review of historical rainfall and prior landslide data, the GEOSCIENCE team created a watershed model, and evaluated pressure heads using a groundwater flow model to analyze water usage. The work of the team, before and during trial, included:

  • Review of historical rainfall data from more than a 91-year period, as well as evaluation of isohyetal maps
  • Research on prior landslide events, correlated with rainfall
  • Evaluation of ground water pressure heads and potential impacts using a groundwater flow model
  • Quantified and annualized water usage for homes upgradient of the slide
  • Review of pertinent reports, witness testimony and other exhibits presented over the course of the trial
  • Preparation of a report summarizing analysis and opinions
  • Expert witness testimony at trial

The highly publicized case, which went to trial in the 2008, resulted in a defense verdict in favor of the City.