Kansas City Water Services desired to rehabilitate a 125-year-old original 114-in. circular brick combined sewer due to its age, deterioration and deflection. Ultimately, a crack had formed in the crown of the structure, affecting the structural integrity of the pipe. The sewer rehabilitation project at 22nd Street & Paseo — under four lanes of heavy duty traffic — is located in the heart of Kansas City, Mo., along the Paseo Parkway.
Design considerations had to include not only sheer size, but many other challenges such as depths up to 35 ft from surface to invert, flow levels averaging 10 to 14 in. during normal operations, bypass pumping (technology dependent), storm surcharging, soil considerations, slope, limited access and two sweeping 90 degree bends with tight radii.
Various technologies were included in the initial assessment, such as: Shotcrete, CIPP, CCCP, FRP sliplining and SPR. Each technology had their particular strengths and weaknesses in regards to maintaining 100 percent of the existing capacity, fully structural design and provide a 50-year solution. The final approved technologies were CCCP, sliplining and SPR.
GETTING STARTED
The project was competitively bid in February 2014 with an anticipated start for mid-summer of that year. Before award of contract was granted, a third
BY BRENT ADAMS
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party stamped design was provided by Brierley Associates to KCMO for the SPR technology. Once the submitted design was received, reviewed and approved by KCMO Water Services, SAK Construction LLC was issued a firm contract and a formal notice to proceed. As a result, construction started in late August 2014. The Sekisui process uses a PVC-based material that is spirally wound into an existing pipeline. Successive wraps of profile are locked together and the annular space between the wound profile and host pipe is grouted. The result is a strong composite pipe integrated with the existing pipeline.
The SPR design called for the installation of a 100-in. ID SPR 102SRW liner with steel reinforcement that is integral within the profile. The primary reason behind using the 100-in. ID liner was due to internal dimensions of the host varying from 108.5 in. to 114 in. with significant deflection at the 4 o’clock and 7 o’clock positions in the crown of the pipe. The dimensions were verified by SAK, using laser profiling equipment, taken every 4 ft. By using the SPR process, the cross sectional loss still increased existing flow capacity, while also providing a fully structural 50-year solution.
WEATHER CHALLENGES
As construction progressed, another encounter was faced head on: Mother Nature. On three separate occasions, SAK personnel were forced to exit the pipe due to rising water from thunderstorms within that particular basin. SAK and KCMO developed and synchronized a communication network between local and national weather services, and the KCMO storm alert system was able to determine when they could safely enter and exit the pipe. Once the storm alert was signaled, SAK would secure the SPR winding machine to the host, cut the PVC profile, remove all ancillary items and safely exit the pipe. After the event had passed and water subsided to manageable levels, the machine was cleaned, profile was re-fed into the machine and construction continued.
The successful winding, bracing and grouting of the 100-in. SPR profile occurred in a continuous live combined sewer through two tight, opposite 90 degree bends. This was completed through existing manhole structures and one new access that the owner required. Matt Thomas of KCMO said,