Inspection and assessment: nobody can quote a liner from a description

Why the survey comes first

A liner is designed, not selected from a shelf. Its wall thickness follows from the condition of the host pipe, its diameter, its depth, the loads above it and whether the existing pipe still carries any of them. Every one of those inputs is a finding.

That is why a quote produced over the phone from a symptom, “it backs up every few months”, is not a quote. It is a placeholder that will be revised once somebody looks, and the revision will not be downward.

It also explains a sequencing detail that surprises people: the line usually has to be cleaned before it can be properly surveyed, and it is surveyed again after cleaning. Both runs matter, for different reasons, see the stage-by-stage walkthrough.

What a survey actually involves

Access and setup

The camera enters through a manhole, a cleanout or an opened fitting. Where no access exists, one is created, which is itself useful information about the eventual lining job.

The camera run

A self-propelled crawler in larger pipes, a push camera in small ones. What distinguishes a professional run from a quick look is method: constant speed, stopping at every defect, recording distances from a fixed datum, and panning at every connection rather than driving past it.

Coding and grading

Defects are recorded using a standardized coding system so that a third party reading the report reaches the same conclusion as the operator who filmed it. Structural defects and operational ones are separated, each with a severity grade and a position along the run.

Measurement

Length from datum, actual diameter, position of every lateral and every bend. On a lining project these numbers are not context, they are the shopping list.

Supporting tests, where relevant

Dye testing to establish where a connection actually goes, smoke testing to find unrecorded connections and defects on a wider network, flow monitoring where infiltration is suspected, and manhole condition assessment, since a sound pipe between two failing structures is only part of a solution.

How to read the report you are given

A useful report answers five questions without needing a conversation. If yours does not, ask for the missing ones before it is used to make a decision.

1. Where does each defect sit, measured from a stated starting point?
2. How severe is it, on a scale that is named rather than adjectival?
3. Is it structural, the wall failing, or operational, such as a deposit or a root mass?
4. Where are the laterals, the bends and the changes of material or diameter?
5. What condition is the line in overall, expressed as a grade rather than as “it's in bad shape”?

Video alone is not a report. It is evidence, and it is worth having, but a two-hour file with no log and no distances cannot be compared with anything, cannot be sent to three bidders, and will not be read by any of them.

The traps worth knowing about

The free inspection attached to a sale

A no-cost camera run offered by a company that also sells the repair is not automatically dishonest, and plenty are done well. It is, however, an assessment produced by the party who benefits from the conclusion. On a project of any size, an independent survey, or at minimum a second opinion on the same footage, is cheap insurance.

The survey done before cleaning, and never repeated

Deposits hide defects. A report written from a dirty pipe understates the condition, and the correction arrives mid-project as a change order.

The conclusion that arrives before the evidence

“It all needs lining” said before the run is complete, or “a point repair will do” said without looking past the first defect, are both the same failure: a recommendation that did not come from the survey.

The missing sag

Standing water in the camera view is the single most consequential finding on a lining project, because it changes the answer entirely. It should be called out explicitly, with its position and extent, see lining or replacement.

What to ask for, in writing

• A coded condition report, not only video.
• Distances from a stated datum, and the direction of travel.
• A separate list of laterals with their positions.
• An explicit statement about grade: is there standing water, and where.
• The raw footage, retained and provided on request.
• Whether the operator holds a current certification in the coding standard used.

None of this is unusual, and none of it is expensive to specify in advance. All of it is difficult to obtain retroactively from a survey that has already been used to justify a quote.

Frequently asked