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Amistad Dam

  • Orange - DSAC II – URGENT (Potentially Unsafe)
    Amistad Dam

The 5-year Dam Safety inspection report indicated the dam is generally well maintained and able to operate under normal and flood conditions.  However, based on the USACE evaluation, Amistad Dam was rated as a Dam Safety Action Class II (DSAC-II, Urgent-Potentially Unsafe).  The report concluded that the entire dam foundation is in need of further evaluation and study due to potential impact of seepage from naturally-occurring sinkholes, and the high risk in terms of the combination of potential loss of life and economic damages.  The inspection report recommended that the Commission convened a joint panel of experts to conduct additional studies.  The dam currently has a hazard potential classification of “High.” 

The "sinkhole area", located within the reservoir pool basin (in Mexico), continues to be monitored for new developments.  No new sinkholes, or related features have been reported since 2002 when the total number of reported features stood at 21.

In June of 2008 the Commission selected and convened a panel of highly qualified "expert" consultants to work under the guidance of agency's Technical Advisors (USACE and CONAGUA) to investigate and evaluate Amistad Dam.  The scope of work was written to include aspects of Dam Safety with a primary focus on the embankment foundation in Mexico. 

The "expert panel" (to include Technical Advisors of the agency) made several site visits, and among other things evaluated current and historical data and documentation, and conducted a potential failure modes analysis for the dam.  The final consensus report and a project plan were developed and finalized in November 2009.

The agency initiated the implementation of several elements recommended in the consensus report, one of which includes the Risk Analysis Study.  Dependent on the results from the Risk Analysis Study and availability of funds, the agency anticipates the initiation of the following work in FY 2010:  1) Foundation and embankment studies, to include stability studies, 2) Installation of additional embankment and foundation piezometers, 3) Further investigation of the "sinkhole area", 4) Further investigation of a previously reported "depression" area located on the upstream embankment, in Mexico, having proximity to the "sinkhole area", 5) A geotechnical "Willow stick Survey" and a Remote Operated Vehicle/Hydrophone survey.

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