Contractor: Insituform Technologies, Inc.
Contract Amount: $734,765.91
Repairing exisiting sanitary sewer systems can be costly and disruptive to neighborhoods. Consider that every home in the City of Denver is linked into the city's sanitary sewer system for disposal. That's many, many miles of pipe carrying waste for disposal, a true necessity for this local population.
But like everything over time, systems wear down and need either replacement or a major overhaul. This project, the 2001 Sanitary Sewer Improvements, is this current year's repair contract for the areas of pipe identified for work. What's unique about this contract is the method of repair, Cured-In-Place-Pipe (CIPP)technology. This method combines custom-engineered felt tubes with thermosetting resins to reconstruct pipelines from existing access points. The pipeline is returned to service within a matter of hours or days as opposed to the weeks or months required for conventional open trench repair. Importantly, this method of pipe rehabilitation has a more than 50 year longevity.
Most sanitary sewer pipe run through the alleys in Denver, allowing for repair that does not disturb street access. This is view of the set-up of a rehabilitation project at Mississippi and Niagara, October 4, 2001.
The custom-engineered felt tubes with termosetting resins (heat activated) are lined with a flexible polyethylene exterior, and must be kept at a cool temperature until placed inside the old pipe.
This ice truck is full of today's standard 10" rehabilitation tubing, and a larger 24" tube for a storm sewer rehabilitation project later on in the week.
Pressurized water is a key component to this C.I.P.P. rehabilitation method. A city hydrant supplies the pressurized water that will be used to "push" the liner inside and through the old pipe.
Later, water must be heated to approx. 200 degrees and flow through the tubing to activate the thermosetting resins to harden in place. This truck contains a huge pressurized boiler for this task.
This ice truck has been moved into place and the tubing is pulled up the scaffolding and fed through the machinery which will begin
the process of inverting the tube at it's point of entry into the pipe system.
The tube is designed with the polyethylene on the exterior and the resin impregnated felt on the interior, at this point of the process. After it is inverted into the system, the polyethylene will now provide a new, smooth lining to the pipe, as the resin hardens the felt next to the old pipe walls, now on the outside of the tube.
Workers begin pulling the tube through the machine where it will begin to be turned inside out and clamped to the machine that will use the pressurized water to both push the pipe liner inside out, into and through the old pipe.
The white felt interior, is now the exterior of the pipe. The thermo-setting resins have a strong odor as they are only applied to the felt tubing within hours of the project, and then kept on ice until the tube is flowed into place.
Later this blue tubing will be flown through the center of the new tubing. It will be connected to the boiler in the other truck and recirculate the heated water needed for curing the pipe. The heated water needs to circulate for approx. and hour and a half to harden the resin.
The machine is now forcing the pressurized water to push through and turn inside out, the resin coated tube.
It takes a while, with some human intervention, to get the tube started into the manhole, turn, and enter the sewer pipe. But once it starts flowing, it lines the pipe within less than an hour.
This project will place 600 feet of tubing into the sewer.
A top-down view of the water filling this dispensing system.
Notice the blue tubing which is now being inserted into the felt tube for heating.
A final view of the tubing in place beginning the curing process with the water heating on the interior.
C.I.P.P. technologies are a highly useful and successful way to repair a broken piping system. They allow the repair to be complete within hours, as opposed to an open trench cut and removal of an existing system. Here, repairs are done quickly and efficiently, with the least disturbance to citizens and homeowners in the area.
For more information about this technology, link to insituform.com