Underground pipe repair in Denver: a decision tree

Step one: locate

Underground pipe repair in Denver starts with knowing exactly where the problem is, in three dimensions. A camera runs the line from a cleanout and records the defect against the footage counter, but footage gives distance along the pipe, not where that point sits under the property. The camera head carries a sonde, a small transmitter, and a locator wand on the surface picks up its signal and gives a spot on the ground and a depth reading. The crew marks it with paint or a flag. That mark and its depth are the most important information in the job, because they say what the defect is under: lawn, a driveway, a slab, a tree or the public street. Two proposals for the same defect can differ entirely on that one mark.

Step two: classify

The camera footage should be coded to the NASSCO PACP system, which assigns each observation a code and a structural or operational grade from one to five. The code separates defect types that call for different repairs: a crack, a fracture, a broken section, a hole, a collapse, a sag or belly, an offset joint, a separated joint, root intrusion, an intruding tap, or a deformed wall. The grade says how far along the defect is. A grade two crack and a grade five collapse are both damage, but only one can be lined. The report should also note the pipe material, since cast iron, clay, Orangeburg, concrete and PVC each fail in their own way, and the diameter, which limits which liner and bursting products fit. A homeowner in Denver should have this coded report before any method is discussed.

Step three: choose by defect type

With location, depth and grade known, the method follows from the defect rather than from preference. The pairings below are the common ones; an explanation of underground pipe repair in Denver walks through how each observation on the video maps to the options.

• Single crack, fracture, hole or bad joint, rest of pipe sound. A sectional point repair: a short fiberglass and resin liner cured on a packer over the defect, bridging onto intact pipe each side.
• Several defects spread along the run, or general corrosion and scale. A full-length cured-in-place liner from cleanout to main, with branch connections reinstated by robotic cutter.
• Root intrusion at many joints. Cut the roots, then a full liner, since a jointless liner removes every entry point at once.
• Collapse, crushed section or an unlined pipe with no round bore left. A liner cannot pass, so pipe bursting pulls a new HDPE pipe through the old alignment, or a dig replaces the section.
• Sag or belly holding water. Lining follows the low spot and keeps it. Correcting the grade means bursting with a re-graded path where possible, or excavation.
• Undersized pipe or a material like Orangeburg that is failing everywhere. Bursting, which can upsize, is usually the answer rather than lining a pipe that has nothing left to bond to.

What depth does to the choice

Depth changes the dig option more than the trenchless ones. A lateral two feet down in soft lawn is a quick trench; the same pipe eight feet down needs shoring, a larger excavator and a much bigger spoil pile, and the disruption of the dig climbs steeply while a liner barely notices. Bursting sits between: it needs a launch pit and a receive pit at each end, so depth matters at the pits, but not along the run. Deep pipe also tends to be wetter, and groundwater in an open trench is a problem a liner never has. As a rule, the deeper the defect, the stronger the case for staying inside the pipe.

What the surface does to the choice

Surface is where the decision tree usually ends. Under lawn, a spot dig for a single defect is honest competition for a sectional liner, and either can be right. Under a Denver driveway or patio, the dig now includes saw-cutting and replacing concrete or pavers, and the trenchless options move ahead. Under a slab, inside the footprint of the house, a dig means breaking the floor of a finished room, and lining or bursting from an exterior pit is nearly always chosen. Under the public street, a permit and traffic control are required and paving restoration is governed by the municipality; lining from the cleanout to the main without opening the pavement is the method the permit office is happiest to see. Property owners weighing how camera inspection and PACP grading guide the repair choice against an excavation should ask for both proposals written to the same PACP report, so the comparison is method against method on the same facts.

When the dig is the right call

Excavation is not the wrong answer; it is the answer for a small set of defects: a collapse under shallow lawn with easy access, a belly that must be re-graded, a pipe too thin or deformed to host a liner or take a bursting head, a broken tap at the main that only an open cut can reconnect, or a replacement being rerouted anyway. In those cases a contractor who proposes a dig is reading the video correctly. In every other case the burden is on the proposal to explain why the pipe cannot be repaired from inside. For any Denver property, verified CIPP installers serving Denver lists installers whose inspection and repair work has been checked, which is where a coded report and a marked location should go for a second opinion.

Common questions in Denver