When Drainage Lines Fail
Underground drainage pipes don't last forever. Root intrusion, ground movement, corrosion, and simple age can cause cracks, breaks, bellies, and complete collapse. When a CCTV inspection reveals damage, you need to decide between repair methods.
Types of Drainage Line Damage
- Cracks and fractures — allow infiltration and root entry
- Offset joints — pipe sections shift out of alignment
- Bellied pipe — sagging section creates a low point that traps water and debris
- Root intrusion — roots penetrate joints and cracks, eventually blocking flow
- Corrosion — cast iron and steel pipes deteriorate from inside out
- Collapse — complete structural failure of the pipe
Traditional Excavation Repair
How It Works
The damaged section of pipe is exposed by excavating a trench, the failed pipe is removed, and new pipe is installed. The trench is then backfilled and the surface restored.
When to Choose Excavation
- Pipe is completely collapsed — trenchless methods require an intact pipe path
- Multiple problems along the entire length — full replacement is more cost-effective
- Pipe material is obsolete (Orangeburg, tar paper) — entire line should be replaced
- Access is relatively easy — open yard, no major landscaping
- Bellied sections that need regrading — trenchless can't fix slope issues
Pros
- Can fix any type of damage including collapse and bellies
- Allows visual inspection of backfill and bedding
- New pipe with full expected lifespan (50+ years for PVC)
- Often more cost-effective for full replacements
Cons
- Disrupts landscaping, driveways, walkways
- Takes longer (3–7 days typical)
- Higher restoration costs for surface features
- Weather-dependent
Trenchless Repair Methods
CIPP Lining (Cured-In-Place Pipe)
A flexible liner saturated with epoxy resin is inserted into the damaged pipe and inflated. Once cured (using heat, UV light, or ambient temperature), it creates a smooth, jointless "pipe within a pipe."
Best for: Cracks, root-damaged joints, minor offset joints, corrosion
Not suitable for: Collapsed pipes, severely bellied sections, pipes with less than 4-inch diameter
Pipe Bursting
A bursting head is pulled through the old pipe, breaking it apart while simultaneously pulling new HDPE pipe into place behind it. This replaces the old pipe with new pipe without trenching.
Best for: Full replacement when the old pipe is too deteriorated for lining
Not suitable for: Pipes under buildings, significant changes in direction, or where upsizing is needed
Spot Repair
For isolated damage in an otherwise sound pipe, a short section can be excavated and replaced, or a point repair liner can be installed trenchlessly.
Cost Comparison
- Traditional excavation (full replacement, 50 ft) — $5,000–$15,000
- CIPP lining (50 ft) — $4,000–$12,000
- Pipe bursting (50 ft) — $6,000–$15,000
- Spot repair (excavation) — $1,500–$4,000
- Point repair (trenchless) — $1,000–$3,000
Making the Decision
Your drainage contractor should present options based on the CCTV inspection findings. Key factors:
- Type and extent of damage — collapse requires excavation; cracks suit lining
- Pipe material and condition — some materials respond better to trenchless
- Surface features at risk — mature trees, driveways, and patios favour trenchless
- Budget — trenchless saves on restoration but the repair itself may cost more
- Long-term plan — lining adds 50 years; excavation with new PVC also adds 50+ years
After Repair
Regardless of method chosen:
- Request a post-repair CCTV inspection to verify quality
- Keep records of the repair for insurance and resale purposes
- Schedule follow-up inspection in 1–2 years
- Address the root cause (tree removal, grade correction) to prevent recurrence