As it turns out, a design flaw was likely the cause for a large crack that was found earlier this year in the large dam North of Tri-Cities on the Columbia River.

In February, during routine maintenance, a 65-foot long, 2-inch wide crack was found on one of the spillway piers on the 8,000 foot wide dam.   The spillways are where the water is released over the dam.  The piers are the large pillars of concrete between the water spillways.

After a thorough investigation, the Grant County PUD found a likely design flaw may have led to the issue.   After lowering the water level over 26 feet,  the crack narrowed considerably.    Officials say the 1950's designers believed the weight of the dam itself would provide enough resistance to the water pressure behind it.

When it was build, it simply "sat" on top of the bedrock under the water.   Unlike many dams, the spillway piers were not anchored down into the bedrock with huge steel reinforcement rods.

Although the dam reservoir has begun to refill now that repairs have been made,  for months people were treated to sights not seen since the area flooded behind the dam over five decades ago.   Docks and boats were left high and dry dozens of yards from the new shoreline, and old foundations,  buildings and artifacts that had been submerged were seen.

Although the repairs cost millions of dollars, fortunately, no other issues resulted from the crack, but it made widespread news across the region.

 

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