The owners of a power plant in West Virginia were constructing a new chimney at an existing coal-fired electrical power plant as part of an overall facilities upgrade program, and to address future emission compliance standards. The chimney was designed to have two fiber-reinforced plastic (FRP) liners. During construction, the liner material caught fire and burned until completely consumed.
The fire created substantial, visible damage to the steel and concrete structural elements. The chimney is 975 feet tall (almost as tall as the Empire State Building) and 82 feet in diameter. The external shell of the chimney is constructed from reinforced concrete that is 1.5 feet thick at the base. Structural steel platforms are located at five different elevations, including the top.
CTLGroup was retained to determine the extent of damage, whether it was possible to remove the damaged material and repair the structure and, if so, how.
This project presented CTLGroup with a significant challenge because of its scale and unprecedented nature. There is no single standard "play book" to address a problem like this. CTLGroup broke the problem down into smaller problems – each of which did have an existing standard procedures – and merged them into a single solution.
CTLGroup led an assessment program that included:
- In-place metallographic assessment of the structural steel
- In-place sounding of the concrete
- Non-destructive concrete assessment (impulse-response)
- Exploratory studies (core drilling)
- Petrographic examination of extracted cores
The CTLGroup assessment program identified that the majority of the structural steel was suitable for use but that much of the reinforced concrete had damage ranging from severe delamination to moderate material alteration. CTLGroup developed a repair program to remove the damaged concrete, and properly prepare the remaining structure so that the repairs would restore structural integrity and the long term durability.