Officials celebrate the end of phase four construction at Bluestone Dam

The U.S. Army Corps of Engineers and its Phase 4 contractor finalized the installation of 278 high strength steel strand anchors in the spillway and non-overflow monoliths at the Bluestone Dam, which they detailed at a celebration Friday in Hinton. (Chris Jackson/The Register-Herald)

The citizens of Hinton are no strangers to construction on the Bluestone Dam.

Work to shore up the dam so that it could handle a once-in-a-100,000-year to a once-in-a-1-million-year event has been going on since right after the turn of the millennium.

Now entering its final phase, which will last well into the next decade, the work on the dam which looms over the river city will continue to impact the residents and visitors for the foreseeable future.

The cause of that impact is because of the nature of the work.

Contractors will need to install a coffer dam — a watertight enclosure pumped dry to permit construction work below the waterline — in the stilling basin beneath the dam's gate. A stilling basin reduces the energy of water released by the dam.

Cutting off flow through one half of the stilling basin at a time, contractors will reinforce the stilling basin with concrete and steel anchors to prevent the scouring of the bedrock below the dam.

Experts believe that if the exposed bedrock that now sits below the stilling basin were to scour during an extreme, never-seen-before release, the dam could slip and cause catastrophic failure and devastation downstream.

Tuesday evening, representatives met with the public at the Ritz Theater in Hinton to discuss their work to ensure that event could never happen and how that work may impact the public's activities around the dam.

To open the event, Aaron Smith, the project manager of the construction, told the audience that progress had been made in the 19 years of construction so far.

"This dam has never been in a better condition than it is today," Smith said. "It is times better than it was five, 10 years ago."

Smith said the Corps is preparing the dam for a "Noah's Ark" event, in which a hurricane or large storm would park over-top the dam's 4,565 square mile drainage basin.

To put the size of where water that flows into the Bluestone Dam into context, Smith said the drainage basin was the size of the state of Connecticut.

"She's a very powerful dam and she has played a very critical role in the state of West Virginia," the project manager said.

The construction of Phase Five will cause a few more headaches for local residents.

With half of the gates inoperable at a given time, officials with the U.S. Army Corps of Engineers estimate that the pool of water above the dam will go above its normal operating height 54 times a year instead of the average 18 times a year currently.

Those increases in the frequency of high water behind the dam will cause activities and access to the lake to be disturbed more frequently, including access to points such as The Pit, the marina, the East Shore campground, low points of Bluestone State Park and campgrounds along the lake.

While expecting more flooding than normal to those low-lying areas, officials with the Corps said that impacts will be entirely weather dependent.

In addition, with the Corps unable to use all of the dam's gates to release excess water, the time of high flows below the dam after a release will increase and impact recreation below the dam. The current day use fishing pier would be closed and most likely removed with restricted downstream fishing access 300 feet downstream of the end sill.

While the work may cause some difficulties during the short term, Corps officials are quick to point out the necessity of the dam to control floodwaters downstream.

According to the Corps, the construction of the Bluestone Dam has saved the state more than $5 billion in flood damages, with half of the water flowing past the state Capitol first coming through Bluestone's gates.

The decades-long refurbishment of the Depression-era dam design will allow the dam to hold back much more water than it can today.

While the dam has yet to see water releases higher than 65,000 cubic feet per second, once construction is completed, the dam is expected to be able to handle releases of 800,000 cubic feet per second without fear of failure.

"Some of the brightest minds in the nation are working on this project," Smith said, pointing toward the anchor cable technique. The technique was first implemented at the Bluestone Dam and is now the standard around the country.

While the project manager understood the public's frustration by the nearly three-decade project, he said all the funds needed to complete the project have been earmarked and that the contract will include mitigation costs to rebuild part of Bellepoint Park.

The needed temporary cofferdam is currently being installed and must be completed by Thanksgiving, with work set to begin in earnest on the main portion of Phase Five in 2020.

-- Email: mcombs@register-herald.com; follow on Twitter @mattcombsRH

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