Rebuilding After Helene: Massive Precast Pipes Help Restore a Tennessee Highway
When Hurricane Helene washed out a section of Tennessee State Route 321 near Butler, residents lost a critical transportation connection to homes, schools, hospitals and jobs. The Tennessee Department of Transportation selected a double-run reinforced precast concrete pipe system to replace the damaged drainage infrastructure and increase water conveyance capacity beneath the roadway. Permatile Concrete Products Company manufactured 408 feet of specially designed, 120-inch-diameter pipe capable of supporting 47 feet of cover. By producing the pipe while crews prepared the site, Permatile helped streamline installation in challenging conditions. The project also incorporated riprap inside the pipes to provide passage for aquatic organisms.
Fast Facts
- Project Name:
- TDOT Route 321 Restoration Project
- Location:
- Butler, Tennessee
- Precast Products Used:
- Pipe, Underground
- Precast Producer:
- Permatile Concrete Products Company
- Completion Date:
- Summer 2026
The Challenge
Hurricane Helene caused a major washout along Tennessee State Route 321 near Butler, damaging drainage infrastructure and disrupting a roadway used by residents, emergency services and businesses transporting goods.
The Tennessee Department of Transportation needed a permanent replacement that could restore the transportation connection while providing greater drainage capacity during future high-water events.
The original project approach involved installing an 84-inch metal pipe inside an existing 96-inch metal pipe. However, the existing pipe had deteriorated and become misshapen, leaving insufficient clearance for the proposed sliplining installation.
TDOT evaluated alternatives and selected a double-run system of larger reinforced concrete pipes to increase drainage capacity.
Construction presented additional challenges. According to the contractor, crews excavated as deep as 60 feet, improved the underlying subgrade and moved approximately 65,000 cubic yards of material to prepare for installation.
The project required close coordination between the contractor, precast producer and TDOT to restore the roadway as efficiently as possible.
Precast Solution
Permatile Concrete Products Company manufactured specially designed reinforced precast concrete pipes for the Route 321 restoration.
The replacement system consisted of two parallel runs of 120-inch-diameter pipe, with a reported total of 408 feet of concrete pipe. Each pipe section weighed approximately 26,000 pounds and was designed to support up to 47 feet of cover beneath the roadway.
Permatile manufactured and stored the pipe sections at its plant while Bakers Construction Services removed the failed drainage infrastructure, excavated the site and prepared the pipe bedding.
Once the site was ready, the contractor, TDOT and Permatile coordinated deliveries so crews could receive and install multiple sections each day despite difficult site conditions.
The design also incorporated riprap placed along the invert, or bottom interior, of the pipes. This provided a passageway intended to accommodate fish and other aquatic organisms moving through the culverts.
- 120 inches Diameter of each reinforced precast concrete pipe
- 408 feet Reported total length of concrete pipe supplied
- 26,000 pounds Approximate weight of each pipe section
- 47 feet Design cover above the precast pipe
- 65,000 cubic yards Material moved during excavation and site preparation
Why Precast?
Precast concrete offered the structural capacity, manufacturing flexibility and installation efficiency needed to replace damaged drainage infrastructure beneath a critical roadway.
Greater drainage capacity: The double-run, 120-inch-diameter pipe system provided a larger replacement for the deteriorated metal culvert arrangement, addressing TDOT’s need to increase water conveyance capacity.
Structural performance: The specially designed reinforced concrete pipes were manufactured to support substantial earth loads, including up to 47 feet of cover.
Concurrent construction: Permatile manufactured and stored the pipe sections while the contractor excavated the site and prepared the bedding. This allowed production and site preparation to proceed simultaneously.
Efficient installation: Completed pipe sections arrived ready for placement, reducing the need for on-site concrete forming and curing. Coordinated deliveries supported installation in difficult excavation conditions.
Aquatic passage: The large pipe openings accommodated riprap along the invert, creating a passageway intended to support movement by fish and other aquatic organisms.
These characteristics made precast concrete a practical choice for restoring drainage infrastructure after a major storm while addressing future hydraulic and roadway loading requirements.
Results
The Route 321 restoration project replaced storm-damaged drainage infrastructure with a double-run reinforced precast concrete pipe system designed to increase water conveyance capacity beneath the roadway.
Permatile supplied the specially designed pipe sections while Bakers Construction Services completed extensive excavation and subgrade preparation. Coordinated production and deliveries allowed the contractor to install the pipe as sections arrived at the site.
The project also incorporated riprap inside the pipes to provide a passageway for aquatic organisms.
The new drainage system was designed to support the restored roadway and accommodate future high-water conditions.
- Written by:
- National Precast Concrete Association
- Source:
- TDOT Route 321 Restoration Project, Built for Purpose Awards submission
- Published:
- October 26, 2026
- Last Update:
- Oct. 26, 2026
Testimonial
"Permatile delivered their product when we were ready to lay it and were great at coordinating with our tight time line."
President, Bakers Construction Services
