Kansas City Water Services (KCWS) had a 922-foot section of a 125-year-old, 114-inch circular brick combined sewer in downtown Kansas City, Missouri, operating under four lanes of heavy-duty traffic along the Paseo Parkway. Over the 125-year life of the original brick combined sewer, severe deterioration and deflection occurred and a significant crack had formed in the crown of the pipe, affecting its long-term structural integrity and motivating KCWS to structurally rehabilitate this massive asset.
Design considerations, in addition to sheer size, presented many other challenges including:
• depths up to 35 feet from surface to invert
• dry weather flow levels averaging 10 to 14 inches during normal operations
• storm surcharging of the combined sewer
• two sweeping, horizontal 90-degree bends with tight radii in this 922-foot section
While various rehabilitation technologies were included in KCWS’ initial assessment to 1) maintain 100 percent of the flow capacity of the original combined brick sewer, 2) offer a fully structural design, and 3) provide a 50-year solution, SAK was the successful bidder on the project with SPR spiral wound PVC. This process uses a PVC-based material which is spirally wound from the surface, through a standard manhole into an existing pipeline, which on this project, eliminated any excavation despite the challenging depth of up to 35 feet from the surface to the invert of the combined sewer. During the winding process, successive wraps of profile are mechanically locked together and once the entire length of the rehabilitated section is complete, the annular space between the wound profile liner and host pipe is grouted. The result is a strong composite pipe integrated with the existing pipeline. The design called for the installation of a 100-inch ID SPR 102SRW liner with steel reinforcement that is integral within the profile, and a 5,000 psi grout filling the annular space between the PVC liner and the host brick pipe. The 100-inch ID liner was specified because the internal diameter of the brick combined sewer varied from 108.5 inches to 114 inches with significant deflection in the crown of the pipe. Despite the cross-sectional loss, due to the smoothness of the PVC material vs. the original brick construction, flow capacity of the combined sewer was increased, while also providing a fully structural 50-year solution.
Being proficient installing the SPR technology on multiple prior projects, SAK was comfortable installing the wound profile in the previously mentioned 10-inch to 14-inch dry weather, live continuous flow, but chose to utilize a 6-inch bypass pump and piping system to transport the 1.5 MGD flow downstream. To safely address storm surcharging, SAK and KCWS developed a synchronized communication network between local and national weather services, and the KCWS storm alert system was able to determine when they could safely enter, work in, and exit the pipe. If the storm alert was signaled, SAK would secure the PVC profile winding machine to the host pipe structure, cut the PVC profile, remove all ancillary items and safely exit the pipe. Once the storm event passed and flow subsided to safe levels, the machine was cleaned, profile was re-fed into the machine and construction continued.
The flexibility of the PVC material permitted successful winding, bracing and grouting of the annular space of the 100-inch ID liner through two tight, opposite horizontal 90-degree bends, without losing any structural integrity. The entire installation was completed through existing manhole structures and one new access which the owner required. Due to the small footprint on the surface and not having to excavate additional access locations, there was minimal interruption to traffic flow on the Paseo Parkway, and traffic control on 22nd Street was limited to one lane closure over a 200-ft section for less than one week, while the profile was being fed down the existing manhole.
The project was completed safely, on time, on budget, while having virtually no impact on the local community. Most importantly, SAK was able to provide the fully structural, 50-year design with improved hydraulic flows for the 125-year-old combined sewer.