The Gatlinburg Wastewater Treatment Plant Failure

By Paul Whitt | October 29, 2015

Many people in the construction industry in Tennessee, and throughout the U.S., heard about the tragedy that occurred in April 2011 at the Gatlinburg Wastewater Treatment Plant (“Gatlinburg WWTP”) in East Tennessee. However, the way in which the failure occurred should be a clear example for designers and contractors when making changes in the field that can impact the structural integrity of a project and to clearly document the genesis and approval of any such changes.

On the morning of April 5, 2011, the east wall of the equalization basin (“EQ Basin”) at the Gatlinburg WWTP suffered a catastrophic failure when the east wall separated from its connections with the interior baffle walls and end walls. The construction of the EQ Basin was completed in the mid-1990’s, so the EQ Basin had been in place for approximately 15 years at the time of the collapse. This east wall was 18” thick, 30’ high, and approximately 124’ long. When it collapsed, it fell onto a control building in which two workers were located. Both workers were tragically killed as a result of the collapse. Also, nearly one million gallons of effluent escaped from the EQ Basin and spilled into the adjacent Little Pigeon River.

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This failure was ultimately investigated by several agencies, including OSHA. A copy of the report issued by OSHA on this tragic failure can be found here: OSHA Report. In short, the OSHA Report concludes that the failure of the east wall was the result of the manner in which “couplers” were used in the connection of the east wall to the interior baffle walls.

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The design called for monolithic pours at the corners and intersection of the east wall and interior baffle walls, with continuous rebar through the connection.

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However, the contractor did not follow the design. Instead, the contractor constructed the walls by creating “cold joints” between the wall intersections and connecting the walls using “couplers” (sometimes called “form savers”). As a result, when the couplers failed, the east wall was allowed to completely separate from the adjoining baffle walls.

The OSHA Report, which provides a very detailed account of the design and construction of the EQ Basin, concludes that the cause of the failure was the deficiency in the construction of the east wall – not the design. The OSHA investigators concluded that the “[w]alls were cast in a manner that produced a cold joint between the wall that fell and the three intersecting walls. … The cold smooth joint facilitated the leakage of the acidic wastewater across the joint, and as a result corroded the rebar splice over a number of years.” The OSHA investigators also concluded that, “The use of the couplers, although a deviation from the design, was not itself a causal factor, but the formation of the cold joint resulted in corrosion of the couplers. Also the rebars were not threaded to the required length inside the coupler at all locations.” Finally, the OSHA investigators noted that the couplers used by the contractor were “neither galvanized nor epoxy-coated, which would have prolonged the life of the basin.”

Obviously, this tragedy resulted in litigation that eventually involved the City owner, the families of the deceased workers, the designer and the contractor. The contractor argued in documents filed with the court that the change in the design was approved by the engineer and was known by the City. The City and the plaintiff family representatives contended in documents filed with the court that the contractor’s superintendent told a City representative that the design change had been approved. However, in the litigation, the contractor was unable to produce any document, such as a change order, that confirmed that the engineer had approved the use of the couplers. The contractor also emphasized that the engineer had a full-time inspector present during the construction of the EQ Basin, including the construction of the east wall. The litigation has since been resolved.

This failure, and the ensuing litigation, provide several important takeaways for designers and contractors. These “lessons learned” include:

  1. Pay attention to the details of changes. While the contractor may have used couplers on many prior projects, and may have believed couplers were very standard in the industry, the use of the couplers in this particular situation proved deadly when the couplers were not protected from the corrosive effluent stored in the EQ Basin.
  2. Document all changes from the design – no matter how small. As a contractor, documenting a change as approved by the project designer is the only safe way to protect the contractor from resulting damage caused by the change. Do not rely on verbal assurances from representatives in the field that a change is approved.
  3. Maintain your project documents. The Gatlinburg WWTP was a public project. The failure occurred approximately 15 years following the completion of the project. In most cases in Tennessee, the statute of repose (which eliminates all claims four years from the date of substantial completion) would protect the designer and contractor from liability. However, the owner of the Gatlinburg WWTP, the City of Gatlinburg, Tennessee, argued that it was immune from the statute of repose and had no time limit on presenting its claims. The families of the deceased workers argued that the designer and contractor were guilty of fraud in construction and/or wrongful concealment of their cause of action, such that the statute of repose did not apply. So, it is best for all project documents to be maintained in some fashion for as long as reasonably possible. Certainly, you should maintain your project documents “forever” on any public projects. For private projects, maintain your project documents for at least seven (7) years following completion of the project.
  4. Staff your project with appropriate representatives. If a full time designer project representative is required, that person should be knowledgeable concerning the design details and alert to field changes from the design.

The story of the Gatlinburg WWTP failure should serve as a wake-up call to the construction industry as to how small changes can cause large failures if not properly reviewed and documented. What is your firm doing to protect itself from this type of failure? What is your firm doing to protect and safeguard its project documents in the event a claim does arise?

Photos: U.S. Department of Labor

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