Everything to Know About the Trenchless Pipe Lining Process

Traditional sewer repairs often require extensive excavation, disrupting lawns, landscaping, driveways, and sidewalks. Modern trenchless pipe lining offers a faster, cleaner alternative, restoring damaged underground pipes with little or no digging.

At Bob Oates Plumbing, Sewer & Rooter, our experienced crews use advanced trenchless technology to rehabilitate aging sewer lines throughout the Greater Seattle area. Most residential projects can be completed in a single day, helping homeowners avoid the disruption and restoration costs associated with conventional excavation.

Here’s what to expect from the trenchless pipe lining process, from the initial inspection and permits through installation and final inspection.

What Is Trenchless Pipe Lining?

Also known as cured-in-place pipe (CIPP) lining, trenchless pipe lining restores damaged sewer lines by installing a flexible, resin-saturated liner inside the existing pipe. Once cured, the liner forms a durable, seamless new pipe within the original line.

This no-dig repair method can address cracks, leaks, corrosion, and damage caused by tree root invasion. It’s an environmentally friendly solution that helps preserve surrounding landscaping and hardscaping while delivering long-lasting results.

A Bob Oates technician prepares a sewer liner before installation. Trenchless sewer repair allows many damaged sewer lines to be restored with minimal digging and disruption to the surrounding property.

How the Trenchless Pipe Lining Process Works

A successful CIPP installation requires careful inspection, preparation, and precise execution. Here’s how our technicians approach each stage of the process.

Secure the Necessary Sewer Repair Permits

Before work begins, the appropriate permits must be obtained. Requirements vary depending on the location, scope of work, and applicable municipal regulations.

As a Registered Side Sewer Contractor (RSSC) serving the Greater Seattle area, Bob Oates handles the necessary permitting and coordinates approvals before installation begins.

Inspect the Sewer Line and Confirm Its Condition

The process begins with a sewer camera inspection. Our technicians guide a specialized waterproof camera through the sewer line to evaluate its condition and identify areas of damage.

A Bob Oates technician monitors a live sewer camera feed while inspecting underground drain lines.

The inspection helps locate cracks, root intrusion, deteriorated sections, and pipe connections. It also allows our team to determine whether the existing line is suitable for CIPP lining.

Severely collapsed pipes, significant misalignment, or other structural conditions may require a different repair method.

Clean and Measure the Existing Pipe

Once the sewer line is confirmed as a suitable candidate for lining, technicians thoroughly clean the existing pipe.

At Bob Oates, our crews use hydro jetting to remove roots, scale, debris, and accumulated material. Cleaning prepares the host pipe so the new liner can conform closely to its interior.

Technicians then measure the pipe and calculate the required liner length and resin quantity. Accurate measurements and careful preparation help ensure a consistent, properly fitted installation.

Bob Oates crew on site clearing a residential sewer line before installing a new liner in the sewer pipe.

Install and Cure the New Sewer Liner

After measuring and preparing the liner, our technicians saturate the flexible liner material with a specially formulated resin. This preparation process, known as resin impregnation or wet-out, helps distribute the resin consistently throughout the liner.

For installations using the inversion method, specialized equipment and controlled air pressure progressively turn the liner inside out as it travels through the existing sewer pipe.

This positions the resin-saturated surface against the interior of the host pipe, allowing the liner to conform to its shape.

A Bob Oates technician sets up the inversion equipment used to install a CIPP sewer liner. Once positioned inside the existing pipe, the resin liner is cured with blue light to form a strong new pipe within the old sewer line.

Once positioned, the liner is held in place while the resin cures. Depending on the lining system and project requirements, our crews use heat or modern UV/blue-light curing technology to harden the liner.

As the resin cures, the flexible liner becomes a rigid, seamless new pipe within the original sewer line. The finished pipe provides a smooth, jointless interior that resists corrosion and helps prevent future tree root intrusion.

After curing, our technicians complete the necessary finishing work and perform a final sewer camera inspection to verify the installation before returning the line to service.

Benefits of Installing Trenchless Sewer Pipe Lining

For Seattle-area homeowners and businesses, trenchless lining offers several advantages over conventional excavation:

• Little or No Digging: Preserves landscaping, sidewalks, driveways, and other property features.
• Fast Turnaround: Most projects are completed in one day or less, minimizing interruptions to your routine.
• Environmentally Friendly: Reduced excavation limits soil disturbance, construction debris, and restoration materials.
• Long-Lasting Results: Properly installed CIPP liners are designed to provide decades of service, with projected lifespans of 50 years or more.
• Reduced Restoration Costs: Avoiding extensive excavation can eliminate much of the expense of repairing disturbed property.

When conditions allow, trenchless lining provides an efficient, cost-effective way to restore underground sewer pipes while protecting the surrounding property.

On this trenchless sewer repair job, Bob Oates techs installed 70 feet of 4-inch liner using blue light curing — restoring service in hours with no digging required. Traditional methods can take up to 48 hours and involve major excavation.

Find Out Whether Trenchless Pipe Lining Is Right for Your Sewer

Experiencing recurring sewer backups, tree root intrusion, or problems with an aging sewer line? A professional camera inspection is the best place to start.

At Bob Oates Plumbing, Sewer & Rooter, our licensed, in-house technicians provide trenchless pipe lining and sewer repair throughout Seattle-area communities. Our sewer repairs are backed by a 20-year transferable warranty, and our estimates are always free.

Already received a sewer repair estimate? We’re also proud to be the Home of the Second Opinion!

Call (206) 789-4944 or contact our office online to discuss your options.