InfraSteel, a permanent culvert rehabilitation system, was used by Midwest Mole of Greenfield, Indiana, to slipline a 245-ft long, 144-in. diameter failing corrugated metal pipe (CMP) culvert under US 31 in Miami County, Indiana.
US 31 is a heavily traveled north-south thoroughfare in Indiana, so the Indiana Department of Transportation determined that sliplining was the best option for repairing the failing structure. The project was bid in the spring of 2017, and construction work was performed in the fall of 2017.
Precision Pipe’s InfraSteel culvert liner is made from smooth wall carbon steel, in custom shapes and sizes specifically for each culvert failure site. InfraSteel has extra copper in the steel for added corrosion resistance and is made in wall thicknesses from ½ to 2 in. thick, which provides superior structural integrity. InfraSteel’s design life is calculated by adding sacrificial steel, for each year of desired life expectancy, to the wall thickness required to handle the existing load bearing requirements.
The existing structure for this site was round and reasonably straight, however, it did have a dip in the middle of the run which was taken in consideration when the size was determined. The other major sizing consideration is the hydraulic capacity of the liner. InfraSteel’s Manning’s coefficient is .012, and inlet and outlet control features are available but were not required for this project.
Midwest Mole had to remove approximately 2 ft of silt from the bottom of the existing structure in order to determine what size would fit inside of the host pipe structure. Once the silt was removed, a survey of the line was completed for both elevations and the alignment of the existing pipe. A mandrel built to the OD of the proposed liner was assembled and pulled through the existing pipe prior to final dimensions of the liner being released for fabrication to verify that no issues would arise once the lining commenced. A round liner with an internal dimension of 135 in. was determined to be the best size for this structure.
D. H. Charles Engineering’s Cardiff, California, office did the load bearing calculations to determine the wall thickness that would meet HS-20 load bearing requirements, considering the worst case with the tire directly over the top of the culvert for vehicle weight with 5 ft of cover, and on 6 ft of cover for soil weight. A sacrificial loss of .280 in. was added to provide the 70-year life expectancy, based on the culvert being located in an immersed zone with corrosive water. A wall thickness of ¾ in. was determined to be the appropriate wall thickness for this particular project.
When construction was ready to begin, the site had to be prepared. “We were working in a creek, so we had to set up a bypass pumping system that allowed us to work in the dry during the majority of the installation. Stormwater control was a critical component of the project that took a lot of time, handling pumps and piping too reroute flows as needed on the creek” says Midwest Mole senior project manager David Howell.
“We were fortunate too that we had a big enough shoulder to set a crane up on the shoulder area and limit traffic disruption,’ he added.
Also, because this was a sliplining project, there was no need to detour traffic off of US 31. There are multiple residences and businesses with access either off of US 31 or from frontage roads which would be affected by detours. This project also coincided with other paving work being done nearby on US 31 that would have caused additional delays or complications in getting both projects completed in a timely manner if road closures or detours would have been required for this work. Road closures and detours are some of the greatest costs associated with culvert failure. Once failure has occurred, and the road has collapsed there is no option for emergency vehicles, commercial vehicles and the traveling public except to detour around the failure.
Midwest Mole unloaded the InfraSteel liner directly from the delivery trucks to the construction pit. Steel runners were installed onto the bottom of the existing CMP to allow the steel liner to ride on top of, as it was being pushed into place. Also, grease was applied to the runners to help reduce friction between the InfraSteel liner and the steel runners, which is the best way to insure a smooth insertion. InfraSteel liner can be pushed into place without using steel runners. However, using bar stock, channel iron or angle iron as a track system definitely facilitates the insertion process for most applications.
A boring machine track was set up in the ditch line of the construction area, and the liner sections were placed on the track. The push pack of the boring machine was used to slip line the sections into place inside of the failing structure. The insertion process of the 245 ft of InfraSteel liner took three days. Once the pipe was in place it was welded from the ID in approximately one week. Midwest Mole used a cellular grout to fill the annular space between the old CMP and the new InfraSteel liner.
This is not the first project where Midwest Mole has worked with Infrasteel. They have performed these installs for various department of transportations. Howell says each of these installations have been successful and Midwest Mole always look forward to the opportunity to work with the Infrasteel team to offer a great solution to various drainage issues in repairing failing pipes. Infrasteel has enjoyed the opportunity to work with contractors such as Midwest Mole, which has been in the trenchless construction industry since 1982, that help to make for a successful project.
States and counties with active culvert inspection programs are less likely to suffer catastrophic failure than those who wait until failure occurs. Many potential failures can be identified from street level as dips in the road or guardrails, where there are creeks or streams, is most often an indication of failure under our roads. Whether it is an application for our product, or another culvert rehabilitation product, we believe it is important to “Rehabilitate Before It’s Too Late.”