We all know replacing aging, failing culverts is a pain. You have to shut down traffic, which results in complaints. Any utilities and road surfaces above the culvert may be disrupted in the process and will need to be repaired again once you've replaced it. The old culvert needs to be dug out and carefully removed, often as it's falling to pieces in the process. Then you need to get the new culvert into place, bury it and repair any surface areas and utilities that may have been damaged in the process. What a pain! Fortunately, there's a much easier way to achieve the same ends: slip-lined culvert rehabilitation. Here's more about how the process works.
Some organizations avoid looking too deeply at the slip-lining process because they assume that they need to invest in the equipment, tools and expertise in-house. That's not true! When Team EJP customer McGee Construction ran into issues with aging culverts in Augusta, Maine, they turned to us for help. In this situation, they needed to replace an aging CMP culvert system that was 20' to the center of the road. Specs called for it to be replaced with a 24" reinforced concrete culvert, but that process would greatly disrupt traffic in the area. The decision to perform a slip-lining rehabilitation of the culvert allowed McGee Construction to meet specs and improve flow over the existing culvert.
But exactly how does the process work? Based on your specific situation, the appropriate size of slip-lining pipe will be selected. Even if your culverts have become deformed, partially collapsed or are not laid out very straight, in many situations we can install a smaller-diameter, smooth-wall slip-lined pipe that will not decrease flow. In the Augusta, Maine example above, an 18" slip-lined pipe was inserted into the existing 24" CMP culvert due to layout issues, but the smooth interior surface still provided a 3% increase in flow, despite the smaller size. Another area that is taken into consideration is the length of the area where the pipe can be laid out. Segmented slip-line pipes enable repairs in tight spaces by taking up less space outside of the culvert.
Once the type and size of slip-lining pipe have been determined, the process is fairly simple. The old culvert is cleaned out well to remove any debris that could hinder the installation process. The slip-line pipe is slid into place, using blocks, runners or anti-flotation devices on an as-needed basis. Concrete bulkheads are built into the inlet and outlet ends of the culvert, leaving grout fill and vent tubes in place. Lightweight grout is poured or pumped into place between the existing culvert and the slip-lined pipe. The fill and vent tubes are cut off and finished. Any inlet or outlet control devices are installed at the ends of the culvert.
By having your existing culverts receive a slip-lined rehabilitation, you not only ensure a longer life for your existing drainage system, but often, you can improve its performance! If you need help determining exactly which slip-lining option is the best for your organization's needs, the experienced professionals at Team EJP are ready to help! Please feel free to reach out today for more information, with any questions about the process or results or to schedule an appointment for a consultation.
