Reline clay sanitary sewer pipe in Denver

Why clay pipe is everywhere, and why it fails

To reline clay sanitary sewer pipe in Denver is to fix the most common sewer lateral in older housing stock across Colorado. Vitrified clay was the standard lateral material for most of the twentieth century because it is chemically inert, resists corrosion and lasts, as a material, essentially forever. Its weakness was never the pipe; it was the joints. Clay came in short lengths, two to five feet, and each was joined to the next with a bell-and-spigot connection packed with mortar, tar or, later, a rubber gasket. A hundred-foot lateral has twenty to fifty joints, and every one is a place where the pipe can move, leak and let roots in.

Over decades, ground moves. Soil dries and shrinks, wets and swells, freezes and thaws, or is compressed by a vehicle above. Rigid clay does not bend with it; the joints open or offset instead. Water leaks out, roots follow the moisture in, and the root mass catches paper and grease until the line backs up. Meanwhile soil washes in through the same openings, and the pipe settles into the void it created. That is the standard clay lateral at fifty or seventy years old: structurally sound sections connected by failing joints.

What a liner does inside a clay pipe

A cured-in-place liner is a resin-saturated fabric tube installed inside the cleaned clay pipe and cured hard. Once cured, it is one continuous pipe with no joints from the cleanout to the main. The clay sections become the form the liner was cast against; the liner carries the load on its own. Roots have no joints to enter. Groundwater has no openings to infiltrate. The small offsets that catch debris are bridged with a smooth transition. For clay pipe specifically, lining is close to ideal because the host pipe is usually still round, still aligned within a fraction of its diameter, and still strong enough to hold shape during the cure.

The steps, in order

• Camera survey. The whole run is recorded with a footage counter. Every joint with roots, every offset, every crack and every branch connection is noted with its distance from the cleanout.
• Cleaning. A hydro jetter scours the pipe and a root cutter removes intrusions at each joint. Clay can take aggressive cleaning; the goal is bare wall from end to end, confirmed on a second camera pass.
• Measuring and wet-out. The liner is cut to length for the run and saturated with resin, usually on a table near the access point, then rolled to work out air.
• Installation. The liner is inverted with air or water pressure from the cleanout, or pulled into place and inflated with a bladder. It is pressed tight against the clay through every joint and offset.
• Cure. Hot water, steam or UV light hardens the resin. The crew holds pressure until the liner is fully cured.
• Reinstatement and final video. A robotic cutter reopens each branch connection sealed by the liner, and the final camera pass records the finished pipe.

For a typical residential clay lateral this is one working day. Crews that do clay sewer pipe lining in Denver regularly will tell you in advance how many branch connections they expect to reinstate and roughly when the plumbing will be back in service.

When clay should not be lined

Three conditions. First, a belly: a section of clay that has settled below grade and holds standing water will hold it after lining too, because the liner follows the pipe. Second, a collapsed section: if joints have separated so far that a piece of pipe has dropped out or crushed, the liner has nothing to press against there, and that section is replaced by bursting or a spot dig. Third, a lateral that has been cabled so aggressively over the years that the pipe wall itself is cracked through along its length; even then lining often works, but the survey should look for it. None of these is common on clay, which is why clay laterals are lined more than any other material.

What you end up with

A lined clay lateral behaves like a new pipe. The inside diameter is a few millimeters smaller, the wall is smooth, and there is nothing for roots to find. Manufacturers generally state the service life of cured-in-place pipe at around fifty years, and the liner is designed to keep carrying the load as the clay around it continues to age. Routine cabling stops. A camera can be run through it at any time. For a description of the product itself, see cured-in-place lining explained, and for a list of installers who have documented their process and equipment for third-party review, see verified CIPP installers serving Denver. The one thing a lining job cannot fix is a crew that skips the cleaning or misses a connection, so watch the footage and count the branches before the liner goes in.

Common questions in Denver