Sequencing the Work
The project broke into two distinct types of work: trenchless rehabilitation on the sections of pipe that could still be lined, and open excavation on the two sections that required replacement. Trenchless work moves faster and leaves the surface intact, so those sections were completed first as weather conditions allowed. The excavation work required removing all water from inside the pipe and blocking the flow upstream as well as creating a large access spot across the surface. The excavation work was more disruptive, so it was scheduled to keep the roadway and entrance open whenever possible and let the property keep running through the project.
The roadway and entrance were closed in coordinated phases to allow the business to remain operational. Best management practices, barricades and signage were set up across the work zone, and the layout was adjusted as the work moved from one area to the next.
Trenchless Rehabilitation of the Intact Runs
A jet/vacuum combination truck cleaned the three sections of pipeline to clear debris and sediment that had accumulated inside, so the new liner would bond cleanly to the existing pipe wall.
Before lining, expansive structural grout was injected around the pipes and surrounding structures, to eliminate future shifting. Decades of water movement can leave voids in the soil around buried pipe, and a liner installed against unstable ground will move with the ground. Stabilizing the soil first kept the new liner installed against a system that would hold its shape and ensures dirt won’t shift.
Three CIPP sections were then installed and cured in place using pressurized steam. Once cured, post-work CCTV verified the installation across all three runs.
Replacing the Collapsed Sections
The collapsed sections could not be lined and had to come out. The work area sat below the water table, so the ground had to be dried out before excavation could begin. A well point dewatering system was installed around the work area to lower the groundwater, and it ran continuously throughout the structural repair. The system was monitored daily, since any extended pause would have let groundwater return to the open pit.
Once the area was dry, the asphalt over the failed sections was sawcut and removed in two 15-foot-wide paths spanning the roadway and parking area. Crews excavated to sand bottom, removed two 20-foot sections of collapsed pipe and installed the replacements.
Restoration and Results
With the new pipe in place, the excavated areas were backfilled in lifts and compacted. The well point system was removed once the ground was stable enough not to need it. The disturbed areas were graded and hand raked, and approximately 800 square feet of sod was installed to restore the landscaped areas around the work zone. Final asphalt restoration was completed by the property’s asphalt vendor over the compacted base, and the temporary closures were lifted as each area was returned to service.
The project rehabilitated three pipe sections with structural CIPP lining and replaced two sections of collapsed pipe that the surface gave no indication were failing. By coordinating all three repairs with AQUALIS, the property avoided multiple mobilizations, redundant closures and fragmented documentation.
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