A host of problems caused the massive crack in Wanapum Dam on the Columbia River, the Grant County Public Utility District said Tuesday.
A team of more than 100 engineers pored through old records for 11 weeks and found three major problems. First, the dam’s 800-foot-long spillway section isn’t anchored to bedrock with steel. Second, crews miscalculated that the concrete mass of the dam could hold the water behind it with its sheer weight. And finally, when crews poured the concrete on that part of the dam on a hot July day in 1960, they may have got that wrong, too.
“We don’t just pour massive sections of concrete at once; there’s large cubes poured. So one of those cubes in this specific section, it might not have cured properly," said Thomas Stredwick with the Grant County utility district.
The $61 million fix involves stitching the dam to the bedrock with steel cabling and rods. And even with 20-hour shifts, seven days a week, Stredwick says all these repairs may stretch out to the end of the year.
