GRANT COUNTY, Wash.--Officials with the Grant County Public Utility District said the primary contributing factor to a fracture in the Wanapum Dam was a mathematical error during the pre-construction design of the dam.
Officials said the fracture forming on a spillway might have been exacerbated by a weak construction joint.
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A team of engineers discovered the mathematical error while examining the original design calculations of the Wanapum Dam spillway. When engineers recalculated the original design formulas, they found that additional concrete and/or reinforced steel should have been included in the construction of the monolith, according to Grant PUD officials.
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Officials said fracture was from a weak point in the spillway that succumbed to the force of the water pushing against it after approximately 50-years of operation.
The results of the investigation from the Grant PUD will be submitted to Grant PUD’s Board of Consultants for final review.