Operation & maintenance of sewerage: which method is typically used to clean small-diameter sewers and remove localized blockages?

Introduction / Context:
Keeping small sewers free of debris is essential for reliable drainage. Different cleaning methods are chosen based on pipe size, access, blockage type, and available equipment.

Given Data / Assumptions:

• Small-diameter branch or lateral sewers in urban areas.
• Access via cleanouts or manholes.
• Localized silt, rags, or grease causing partial blockage.

Concept / Approach:

Cane rodding uses flexible rods coupled together with end tools (corkscrews, cutters) to manually break, hook, or push blockages through small sewers. It is quick, targeted, and requires minimal water—well suited for small lines. Flushing is useful for larger sewers or after loosening deposits; wooden pigs are more common in larger conduits or pressure mains, not small gravity laterals.

Step-by-Step Solution:

Verification / Alternative check:

Post-cleaning CCTV inspection (where available) verifies clearance and pipe condition.

Why Other Options Are Wrong:

(a) Flushing alone may not dislodge stubborn blockages; (c) wooden pills are uncommon in small lines; (d) incorrect because a standard method exists.

Common Pitfalls:

Forcing tools that damage joints; ignoring safety and confined-space procedures; not addressing sources of repeated blockages (grease control).

Final Answer:

Cane rodding using flexible rods and tools