We're living with 60- to 100-year-old underground systems. Understanding how they were built leads to insightful repair and maintenance. Note the bedding and hot tar joint fill, and the worker's apparel.
Over time, fine soil particles filtering into the pipe build up and reduce capacity. Injecting chemical grout structurally corrects pipe alignment and provides a permanent and positive joint seal on the outside of the pipe.
Joints, service line connections, and cracks are the primary sources of groundwater infiltration in sewer systems. Chemical grout seals pipes, reduces excess flow, and lowers costs at the wastewater treatment plant. Cement grout, on the other hand, is used primarily for new construction: dams, tunnels, and subways.
During reconstruction of the World Trade Center, the contractor used AV-310 hydrophilic polyurethane resin around soil anchors. The crew used the V-PAC method and fitted each tieback cable housing with a steel cap, injection port, and relief valve to keep the grout in place long enough to cure and stop the leaks.