Stantec’s Support Of TVA’s Coal Ash Spill Recovery Earns Awards For Engineering Excellence

Wednesday, June 4, 2014
The Kingston Coal Ash Spill/Failure of 2008
The Kingston Coal Ash Spill/Failure of 2008

Stantec has received the Grand Award from the American Council of Engineering Companies of Kentucky. The award recognizes Stantec for its design and technical solution for the Tennessee Valley Authority’s recovery from the Kingston coal ash spill. The project also received a National Recognition Award at the ACEC 2014 Engineering Excellence Awards competition.  

In December 2008, the dikes at TVA’s power station in Kingston, Tennessee containing wet coal combustion ash failed, and 5.4 million cubic yards of coal ash were released. The ash slurry flowed out from the site, impacting the adjacent Emory River In the aftermath, TVA committed more than $1 billion for the response, clean up, and site restoration. 

Stantec’s team was at Kingston within hours after the spill to assist TVA with emergency actions. As the recovery progressed, Stantec developed a site closure scheme, completed detailed engineering designs for a containment structure, and remained on-site to help with recovery efforts.  

Today, TVA has achieved several key milestones at Kingston. During the first two years after the spill, about three million cubic yards of ash dredged from the river was shipped by rail to a permitted, off-site landfill. Since then, the remainder of the released material has been excavated and stacked back inside the footprint of the failed impoundment facility. A two-mile long perimeter containment structure has been built around the new 240-acre ash landfill, which is being capped with a flexible membrane cover system.  In 2014, Stantec’s design was recognized by ACEC for engineering excellence.

The idea of placing large volumes of ash back within the failed area was met with initial skepticism, said officials. To prove it could be done without causing another failure, a test embankment was built across six acres of the failed dredge cell. Geotechnical instrumentation was installed to measure water pressures and movements within the underlying ash. Stantec established criteria and monitored conditions. In the end, more than 250,000 cubic yards of ash were safely stacked to a height of 45 feet above the failed surface. In addition to restoring confidence, the test program established protocols that would be followed throughout the project.

By far, the most difficult design challenge was how to contain the ash in the event of a large earthquake, said officials. Tennessee regulations require landfill facilities to withstand a 2500-year earthquake. Engineering analyses showed that these events would liquefy the sandy soils underlying the ash landfill.

Borrowing an approach used elsewhere to stabilize large embankment dams, Stantec designed a grid of buried walls that enclose the ash landfill. The engineering design was complex and required advanced numerical modeling of the seismic behavior, using both dynamic 2D and static 3D structural analyses. The design was subject to extensive independent review and regulatory oversight. The completed retaining structure, built to depths of 70 feet, is one of the largest walls of its type ever constructed in the U.S. 

Craig Zeller, EPA’s project manager at the site, sees how far the cleanup project has come. “It was a daunting project at the start. But five years later, after dredging, digging, and stacking ash day after day, week after week, the end is in sight. The project is on schedule. Ash is out of the river. The perimeter walls are done. The environmental restoration is underway. Kingston is a fantastic case study for a large-scale cleanup,” Mr. Zeller says.

TVA’s Kingston, Tennessee, Fossil Plant supplies power that is critical to the regional economy. On-site storage of the recovered ash, made possible with the perimeter containment structure, represents TVA’s best option for meeting both the economic and environmental goals of the project. The result has restored public confidence that a failure like the 2008 event would not happen again at Kingston, not even during a major natural disaster like an earthquake, said officials.



New Hamilton County Businesses

Here are the new business licenses from the County Clerk's office: AB INDUSTRIAL 7226 TENDERFOOT TRAIL OOLTEWAH, TN 37363 ADVANCE CLEANING SERVICE 4000 LANA LANE APT  C CHATTANOOGA, TN 37416 APPAREL INK 3661 BRAINERD RD STE 303 CHATTANOOGA, TN 37411 BEZALEL TECHNOLOGIES INC 12 S SWEETBRIAR AVE CHATTANOOGA, TN 37411 BP SOLUTIONS 1403 ... (click for more)

MAU Hosts Hiring Event This Monday

MAU is hosting a hiring event this  Monday, from  9 a.m.-2 p.m.  to fill job openings for  automotive assemblers  in Chattanooga.  The job fair will take place at MAU Workforce Solutions, located at 6150 Shallowford Road, Suite 104 in Chattanooga.  Qualified candidates must submit to drug screen and background check. Position ... (click for more)

Circuit Court Clerk's Office Hit With New Scam

Circuit Court Clerk Larry Henry said his office has been hit by another scam. He said a number of county residents are getting calls saying it is from a collection agency and they owe money through his General Sesssions Court civil division. Circuit Court Clerk Henry said, "These people are saying that if you do not pay up, you will be prosecuted and the sheriff will come ... (click for more)

Athens, Tn., Doctor, Wife, Daughter Die In Crash Of Small Plane That Hit House Near Boston

An Athens,Tn., physician, his wife and college-age daughter died Sunday evening in the crash of a small plane that struck a house 30 miles southwest of Boston on Sunday evening. The victims were Dr. Joseph Rick Kalister, the emergency room director at Starr Regional Medical Center's Athens campus, wife, Betty, and their daughter. The doctor and his wife were en route for a ... (click for more)

Six Commissioners Owe Us An Explanation - And Response (2)

Two-thirds of the Hamilton County Commission owe us an explanation as to why they feel it appropriate to take $900,000 of our money out of savings to spend on whatever suits their fancy, oversight be darned.  Those six commissioners are: Randy Fairbanks (D-1), Jim Fields (D-2), Warren Mackey (D-4), Sabrena Turner-Smedley (D-7), Tim Boyd (D-8), and Chester Bankston (D-9).  ... (click for more)

Roy Exum: Tonight, Take A Second

Peter Whibberley, known globally as “The Time Lord,” will freely tell anyone, “There are consequences of tinkering with time,” but tinker we must because the world – planet Earth -- is spinning slower. So tonight at 7:59:60 p.m. EDT, the Senior Research Scientist at Britain’s National Physical Laboratory will add an extra second to the hour – and our day -- before it becomes 8:00 ... (click for more)