Wanapum Dam: 65-ft Crack Discovered on Wanapum Dam

Wanapum Dam is a hydroelectric project located on the Columbia River downstream (south) from Vantage, Washington where Interstate 90 crosses the Columbia from Grant County into Kittitas County. It is owned by the Grant County Public Utility District. Its reservoir is named Lake Wanapum.

65-ft Crack Discovered on Wanapum Dam

Grant County, Washington – Inspectors have confirmed the discovery a two-inch wide 65-foot long crack at the base of the Wanapum Dam which is downstream from this Central Washington county. Authorities were quick to dispel any notion of a risk to local residents. However, the crack is of a sufficient severity to invoke an emergency response countermeasure. The water level at the dam was dropped by 20 feet to reduce the pressure on the dam.

“At this point we already know there’s a serious problem,” said Thomas Stredwick, spokesman for the Grant County Public Utility District (PUD). “We want to make sure the spillway is stable enough that inspectors are safe when inspecting it.”

However, the full extent of the damage isn’t known at this time. The lower water level should increase the stability of the dam and provide additional security for the inspection team that will be examining the crack in greater detail to determine what is wrong and how to fix it. What authorities want is increased safety at the spillways so that inspectors are not a risk when conducting a physical inspection of the damage.

The problem was first alerted by an engineer who noticed an irregularity in the shape of the spillway that cars pass by when traversing the dam, but it wasn’t until a diving team checked out the base that the two-inch wide crack was found and traced over a distance of 65 feet.

Divers have discovered an underwater crack in one of the concrete piers, shown, below the fourth spillway gate at Wanapum Dam. The crack was discovered after dam engineers Tuesday noticed some mild irregularities in the concrete of the dam’s deck. The Grant County PUD has lowered the reservoir behind the dam by six feet to relive pressure. The dam is still generating electricity as usual while the investigation continues. The dam is on the Columbia River near the community of Beverly, 62 miles south of Wenatchee. (Photo courtesy of the Wenatchee World)

According to reports, officials with the Bonneville Power Administration (BPA) declined to comment on the potential impact to power generation because they did not want to unduly influence energy markets.

But Kevin Wingert, a BPA spokesman, said the immediate impact would be an increase in flow from Priest Rapids Dam downstream, which would, temporarily exceed the low flows needed to protect chinook salmon redds through the Hanford Reach area.

Wanapum Dam was built in 1959 and is more than a mile long. The piers supporting its 10 spillway gates are each 65 feet wide, 126 feet tall and 92 feet deep.

Source:
Wanapum Dam crack
http://seattletimes.com/html/localnews/2023019385_wanapumdamxml.html

65-foot crack discovered in Wanapum Dam a ‘serious problem’
http://www.yakimaherald.com/news/yhr/saturday/1970390-8/65-foot-crack-discovered-in-wanapum-dam-a-serious