How Manhole Rehabilitation Prevented Structural Collapse and a Train Derailment

September 12, 2022

Written By Matt Huston

Failing manholes can be detrimental to an industrial plant's operations by causing sewer line blockages, damage to transportation routes and more. If the circumstances are just right, failing manholes also pose the extreme risk of cave-ins which not only cause major damage to the infrastructure above, but are also extremely dangerous.

Recently, our team of manhole rehabilitation contractors completed a sanitary sewer rehabilitation project at a food processing plant. Three manholes were in a state of complete failure, one of which was positioned below two sets of railroad tracks adding additional challenges. The HK team acted quickly to find a solution that would not disrupt the plant’s operations and could be completed before a structural collapse caused a sewer backup and train derailment.

Inspecting the Manhole and Pipeline Infrastructure

Prior to selecting a solution for manhole rehabilitation, careful consideration is required. With this particular project, our Pipeline Inspection & Proactive Evaluation (P.I.P.E.) team visited the site and conducted a 3D manhole scan and a complete inspection of the infrastructure. Our manhole scanning tool identified several areas of concern, and the data revealed that all three manholes were in need of immediate action.

Signs of A Failing Manhole

Recognizing the signs of a failing manhole is a crucial component in working to prevent damage to the infrastructure above, diminishing costs associated with repairs and avoiding a halt in traffic and business operations. During our inspection at the plant, we noticed the following signs of a failing manhole:

• Pooling water
• Cracking around the manhole
• Visible damage to the manhole cover
• Inflow & infiltration concerns
• Corrosion within the manhole and sewer
• Deterioration of blocks or bricks

Similar projects are often referred to our manhole rehabilitation experts after manhole inspections reveal these signs of deterioration.

In finding these signs of manhole failure in all three manholes, our team acted quickly to ensure operations continued with no downtime, that cargo was able to be delivered as expected and that no one experienced harm.

The Imminent Risk Posed by Failing Manholes

As the three manholes remained in a state of failure, there was an imminent risk of complete structural collapse and catastrophic failure, which would have caused an industrial sewer back up and a very possible train derailment. As our manhole rehab technicians took the situation into careful consideration, they knew that digging and disrupting surrounding areas for manhole replacement would greatly impact the sets of train tracks. As there was no time to spare, the HK team had to deploy our team of manhole rehabilitation contractors to come up with a trenchless solution immediately.

Finding a Solution to Keep the Impacted Railway Operating

Our top priorities when choosing a sanitary sewer rehabilitation solution for this project were to ensure the railway continued operating, so the plant could receive shipments as normal, and to keep the cost of rehabilitation at a reasonable level.

Excavation was an option, however an extremely pricey option. Not only would it require digging to complete the manhole rehabilitation, but the cost to restore the infrastructure above would have been very high. Our team had to select a manhole rehabilitation solution that could work within the confines of the situation at hand and withstand corrosive environments with high levels of hydrogen sulfide (H2S) and the weight of a freight train.

Based on the information gathered, Monoform PLUS™ was the ideal solution. It is an innovative, trenchless manhole rehabilitation solution that is 100% structural and 100% corrosion-resistant to protect sewer structures exposed to corrosive environments just like the environment at the plant.

The Trenchless Manhole Rehabilitation Process

After the PIPE team performed the inspection and a solution was determined, the manhole rehabilitation team worked with the City of Des Moines and the food processing plant to develop a timeline for the project. Totaling approximately 36 vertical feet of structural wall lining between all three manholes, each manhole received a brand-new HDPE (high density polyethylene) bench & invert and brand new composite castings.

From start to finish, the project was completed in three weeks and just in time, avoiding complete structural collapse.

Why Monoform PLUS™ Was the Ideal Manhole Rehabilitation Solution

There was a lot at stake with this project and Monoform PLUS™ was the ideal solution because it met all of the necessary conditions. 

Monoform PLUS™ allowed for complete structural manhole rehabilitation with the following benefits:

• Minimal to no downtime - Operations were able to continue running smoothly while our crew were hard at work.
• No digging required - As a trenchless manhole rehabilitation solution, Monoform PLUS™ does not require excavation.
• Cost effective - There is no cost related to rebuilding infrastructure when the solution is trenchless.
• Corrosion resistant - The AGRU Sure Grip HDPE liner 100% Corrosive-resistant and protects the newly installed concrete for a complete lifetime. 
• Fully Structural - Monoform PLUS™ is designed to handle Cooper e80 load, which is equivalent to a fully loaded freight train.
• Long lifespan - Our traditional Monoform™ solution and Monoform PLUS™  have an equivalent lifetime to that of a full replacement, so the rehabilitated manholes are protected for the next 100 years.

With the help of Monoform PLUS™, the plant operations were able to continue as usual.

Reach Out to HK’s Manhole Rehabilitation Experts

Our Monoform™ and Monoform PLUS™ solutions have a wide variety of municipal and industrial applications. Our team is capable of tackling manhole rehabilitation projects of many sizes and conditions of deterioration.

Whether you need an inspection to identify the condition of manholes or you’re ready to learn about manhole rehabilitation solutions, our team is here to help. Reach out to HK to learn about your options or give us a call 855-845-5326.