HDPE Pipe Joint Sealing
THE JOB
A large sinkhole opened up in the parking lot of a manufacturing facility. The sinkhole was adjacent to a cast-in-place stormwater drop inlet structure. The structure was 14VF deep and was fed and discharged by 54″ HDPE pipes, requiring HDPE pipe joint sealing.
Facility maintenance personnel had been monitoring the sinkhole and noted that it was growing rapidly. Inspection of the pipe revealed that there were joint failures at the first joint out from the manhole and deterioration of the parging. The parging between the HDPE and concrete pipe had failed to the point of significant amounts of soil washing out during rain events.
THE CHALLENGE
The repair could not disrupt traffic in the parking lot or other facility operations. It also had to provide a long-term solution to the failed pipe joints.
Along with gently filling the voids around the HDPE pipe without deflecting or damaging it, the repair material had to have enough expansive force to thoroughly seal the small cracks and leaks in the parging between the HDPE pipe and concrete structural walls.
THE SOLUTION
Chemical grouting using both prepolymer chemical grouting and plural component polyurethane grouting.
Chemical grouting was chosen for injection through the joints of the HDPE pipe. Prepolymer chemical grouting uses single component polyurethane grouts with exceptionally long gel times. This virtually eliminates localized expansive pressure, which could further damage the HDPE pipe, which was already out of round.
The plural component structural foam was used for void filling the large sinkhole that extended from the bottom of the structure to the surface.
Prepolymer chemical grout was injected through the joints in the HDPE pipe. This successfully sealed the bell and spigot joints without causing further deflection of the pipes.
The large sinkhole void was grouting using plural component polyurethane grouting. Due to void size, CJGrout 20SDB is the best material due to its low exotherm. Structural foams are important in situations where there are very large voids in areas subject to traffic loading.
Speak With An Expert
Facing a similar challenge to this HDPE pipe joint sealing project? Give us a shout or shoot us a text. Click the state marker for the location of the project for contact info for the appropriate rep.
Dam Outfall Pipe Seep Grouting
THE JOB
This dam outfall pipe seep grouting is located in Fairfax, Virginia at Northern Virginia Community College. A 36″ RCP outfall pipe for a dam terminated at an end wall. As part of a dam rehabilitation, small seeping leaks at the end wall/pipe joint needed to be stopped. The leaks had to be stopped so the wall could be resurfaced.
The engineer specified chemical grouting.
THE CHALLENGE
Access to the area was quite difficult. It was more than 150 feet from the closest vehicle access, which was only accessible by 4×4 vehicles down a steep slope.
While unknown during the planning of the chemical grouting repair, what was thought to be 36″ RCP was actually a larger diameter RCP that had been lined with steel casing pipe. An interior poured-in-place concrete liner had been installed afterward.
THE SOLUTION
Super low viscosity prepolymer chemical grout was selected. This was for two reasons: 1) the ability to easily pump more than 150LF from the lay-down area. 2) the ability to seek out and stop leaks through very tight cracks in the structures.
Prepolymer chemical grouts are water-reactive, so can be injected into active water flows. The grout expands when it comes into contact with the water, which seals the leak.
The initial grouting plan was to install the chemical grout through the pipe wall starting beyond the first joint. However, because the pipe had been cased, placement had to be done through the end-wall structure only. Multiple injection holes were drilled through the end wall structure, and the chemical grout was pumped through the end-wall structure.
Extensive catalyzation was used to first seal the leaks at the end wall and then chase the water flow pathways up along the outside of the pipe. The job was messy due to the forced proximity of the injection points and the leaks. But all the leaks were successfully stopped.
Speak With An Expert
Facing a similar challenge to this dam outfall pipe seep grouting project? Give us a shout or shoot us a text. Click the state marker for the location of the project for contact info for the appropriate rep.
