HAL investigates Sandy City fluoride incident

Sandy City, Utah, experienced a fluoride overfeed at one of its drinking water wells in February 2019. Immediately following the incident Sandy City asked Hansen, Allen & Luce (HAL) to begin modeling and investigating.

First, HAL updated a winter-scenario hydraulic model that informed the initial response. The computer model showed the concentration and extent of fluoride in the distribution system. HAL continued to refine the model over the coming weeks, creating a forensic version that matched results from numerous water samples.

Over the next year, HAL worked with water system staff, attorneys, the Utah Division of Drinking Water, and the Salt Lake County Health Department to investigate the incident. HAL helped determine the cause of the overfeed, document the City’s response, and recommend improvements to facilities and procedures to prevent future incidents. HAL then prepared the investigative report submitted to regulatory agencies.