Sewer Line Repair Versus Replacement Assessment

Purpose

The decision between a spot repair, a liner and a full replacement is made against the distribution of defects along a line and the structural fitness of the host pipe, not against the worst thing on the video. A single spectacular offset in an otherwise sound run is a spot repair. Five unremarkable open joints over 60 ft is a replacement, though no one of them looks bad enough to justify it, because the shop that repairs the worst will be back for the second-worst inside two years.

A recommendation built from the most dramatic frame sells a repair the customer believes ends the problem, and when the line backs up again the shop has spent its credibility on the wrong work. The way out is an evidence set gathered in a fixed order, one stated rule applied to it, and the deciding criterion named on the ticket.

Scope

Covers assessing a building sewer or building drain serving a house, a small retail space, a small restaurant or a small multifamily building, and producing a written recommendation of spot repair, lining or full replacement, with the evidence attached.

It does not cover performing any of those repairs, nor the camera procedure itself, which the sewer camera inspection and report SOP owns, nor clearing the line, nor root treatment, which has its own SOP and exit criterion. Excavation belongs to the crew. Anything past the property line is the utility's, and is documented rather than quoted.

Roles and the handoff

Procedure

The decision rule this SOP runs on, applied per line and never per defect, with the replacement criteria checked first:

• Spot repair when ALL of these hold: one or two actionable defects, at least 20 ft of sound pipe on either side of and between them, no belly holding water deeper than 25 percent of the pipe's internal diameter, and sound material elsewhere.
• Lining when there are three or more actionable defects, AND the host pipe holds round through the run within the liner manufacturer's stated ovality limit, AND the grade is already acceptable, since a liner follows the pipe it is installed in and corrects no grade at all.
• Full replacement when ANY of these is present: a collapsed or missing section, a belly over the 25 percent gate, a grade defect, or a material the liner system is not qualified for.

1. Get the line flowing and confirm it is free before any assessment begins. Acceptance: normal flow witnessed from two fixtures and a written statement that the line was free when surveyed. Stop rule: a surcharged or partly blocked line is cleared first under the drain cleaning standard and the assessment rebooked, because standing water hides the invert, which is where the wall goes first. Hazard: an exterior or stack-base plug on a line that may still be holding is cracked one flat at a time from beside the opening with containment set, never square in front of it and never overhead.

2. Run the camera to a defined end point and record the zero and the end. Acceptance: the zero point named, the run terminating at the main connection, the property line or the reel's usable length, and the end condition stated. Stop rule: a run stopping on an obstruction short of the intended end is incomplete evidence, so no recommendation is issued from it and the line is cleared and re-surveyed first. Hazard: the reel is a corded assembly beside an open sewer opening, so it runs on ground-fault protection with the test button proved first, per 29 CFR 1926.404(b)(1) on construction work and 29 CFR 1910.304(b) in general industry.

3. List every defect by footage and put each in one of four classes. Sound joint, open joint, offset or deformed, and missing or collapsed. Acceptance: a numbered list with a footage and a class for each, the material and any transition noted at its footage, and a count of the actionable ones, meaning everything except sound joints. Stop rule: a feature you cannot classify is filmed again on a second pass rather than guessed at, because the count drives the decision and one miscounted joint moves a line between two answers. Hazard: none at this step, it is a classification made at the monitor, and saying so is better than leaving the clause blank.

4. Measure any belly as a fraction of internal diameter, and record its length. Acceptance: the standing water depth read against the known internal diameter, stated as a percentage, plus the footage over which it stands. Stop rule: a belly at or over the 25 percent gate ends the lining option there and then, because a liner follows the existing grade, and the recommendation is replacement of at least that section regardless of what else the line shows. Hazard: none at this step, it is a measurement read off the camera.

5. Test the lining question against the host pipe and the branch connections. Acceptance: the run confirmed round within the ovality limit the liner manufacturer publishes for the system your shop uses, under the installation practice that system is qualified to, such as ASTM F1216 for an inverted cured-in-place liner; every branch connection listed by footage with a note that each must be reinstated after lining; and the diameter loss stated to the customer. Stop rule: missing wall, a collapse, or ovality past the manufacturer's limit cannot host a liner, so lining comes off the table rather than being offered with a caveat. Hazard: none beyond the open access already controlled, and the branch list is what stops a lined line from leaving a bathroom disconnected.

6. Walk the surface and price the access constraint honestly. Acceptance: measured depth at the shallow and deep ends, the surface over the line, mature trees within a stated distance, other utilities from the one-call locate, and the property line marked. Stop rule: no quote goes out without a placed one-call locate, because a lateral running under an unmarked gas service changes the method, the crew and the risk. Hazard: probing for depth can strike a buried service, so it happens only after the locate is marked and hand-dug inside the state's tolerance zone; if a gas line is struck, everyone leaves upwind at once, nothing is started or switched, and the call goes to the utility and emergency services from a distance.

7. Apply the rule and name the criterion that decided it. Acceptance: the actionable defect count, the longest sound run in feet, the belly percentage and the host-pipe verdict written down, then one sentence naming which branch of the rule the line fell into and why. Stop rule: a line satisfying no branch cleanly is written up as inconclusive with the missing evidence named, rather than pushed into the branch the shop would rather sell. Hazard: none at this step, it is a decision made at a desk with the footage in hand.

8. Close the access, restore flow, and hand over the evidence with the recommendation. Acceptance: the plug back in with its sealant and the joint dry, flow witnessed again from two fixtures, and the customer given the footage, the defect list and the criterion sentence. Stop rule: a plug that will not seat is replaced now, not snugged and left, since the next person to find it will find it under a surcharged line. Hazard: this step puts the line back into service, so the flow witness is the verification that what you opened is closed and working, and the customer is told plainly that the line is unrepaired until the recommended work is done.

When the site does not match this procedure

The defect is past the property line. Document the footage, the locate mark and the property line, and hand it to the utility. Do not quote right-of-way work on the shop's own authority.

The customer wants a price today from a partial run. Give them the partial evidence and the price of completing the survey. A number quoted off an incomplete run is one the shop will have to move later.

The customer refuses excavation. Say which options remain and what each does not fix. A liner in a line with a belly is not a compromise, it is a repair that does not address why the line backs up.

The record this produces

• Line free or surcharged at survey, and how that was established
• Zero point, end point and end condition of the camera run
• Numbered defect list: footage, class, material, every material transition
• Actionable defect count and longest sound run in feet
• Belly depth as a percentage of internal diameter, and its length
• Host-pipe verdict for lining, with branch connections by footage
• Depth at both ends, surface, trees, located utilities, property line
• The rule branch taken and the criterion sentence

The criterion sentence is what survives a second opinion. "Replacement, driven by a 37.5 percent belly at 55 ft" can be argued with on its facts; "line is in bad shape" cannot be argued with at all, which is why it loses.

Worked pass: 1958 house, 4 in cast iron to clay, repeat backups

Intake: third backup in 18 months, line cleared two weeks ago, assessment booked as its own visit.

• Step 1: both baths and the kitchen run with normal flow, line confirmed free at survey.
• Step 2: FAILED on the first attempt. The run zeroed at the exterior cleanout and stopped at 66 ft on a soft obstruction, short of the main connection. Stop rule taken: no recommendation issued, the line cleared under the drain cleaning standard, and the survey re-run the same afternoon to the main connection at 74 ft.
• Step 3: on the complete run, defects at 12 ft channeling in the cast iron with the bottom of the wall gone, 30 ft cast-to-clay transition offset about a third of the wall, 41 ft open joint with roots, 55 ft belly, 66 ft open joint with roots. Five actionable.
• Step 4: standing water at the 55 ft belly measured 1-1/2 in against an internal diameter of about 4 in. That is 1.5 divided by 4, or 37.5 percent, over the 25 percent gate.
• Step 5: lining was already off the table on the belly, and the 12 ft channeled section confirmed it independently, since a host with missing invert wall sits outside what the liner manufacturer's practice covers. Branch connections noted at 22 ft and 48 ft.
• Step 6: depth 26 in at the cleanout and 52 in at the main connection, lawn and a driveway apron over the line, a mature maple 8 ft off the run, locate marked, property line at 71 ft.
• Step 7: five actionable defects against a spot-repair ceiling of two; longest sound run is 55 minus 41, or 14 ft, against the 20 ft that branch requires; belly at 37.5 percent, over the 25 percent gate; host unsuitable for lining. Full replacement, and the criterion sentence names the belly, since that one alone forecloses both alternatives.
• Step 8: plug reset with sealant, joint dry, flow witnessed from two fixtures, footage and defect list handed over. The replacement scope carries the minimum slope for 4 in pipe read from the slope table in IPC Section 704, which is 1/8 in per foot in the edition in force here.

The incomplete first run is the part worth keeping. Had the tech recommended from what stopped at 66 ft, that open joint would never have made the list, the count would have read four rather than five, and the line would still have landed on replacement - but on a partial picture, which is the write-up a second opinion picks apart.

References

• The liner manufacturer's published ovality and host-pipe limits for the system your shop installs, and the installation practice it is qualified to, such as ASTM F1216 for inverted cured-in-place lining
• IPC Section 704 and its slope table, or the corresponding UPC drainage provisions, in whichever edition your jurisdiction has adopted, for the slope a replaced line is laid at
• The state one-call locate that must be placed before any probing or digging, and your excavation standard, which governs the dig itself once the work is handed to the crew
• 29 CFR 1926.404(b)(1) for ground-fault protection on construction work and 29 CFR 1910.304(b) for the general-industry branch-circuit requirements
• See related: the sewer camera inspection and report SOP, the root intrusion treatment and recurrence plan SOP, and the recurring clog investigation SOP