Most sewer blockages occur in small diameter pipes, often near the head of sewer systems. With impending changes in ownership of private sewers / laterals, the numbers of small diameter pipes operated by Utilities will increase, with implications for effectively managing these assets.
Blockages account for over 90% of "other causes" for sewer flooding, but there was a lack of understanding of exactly how blockages form. Factors contributing to blockage formation include misuse (fat, grease, nappies etc.); poor joints (including tree root ingress); slack gradients and low flows, but the significance / risk of each is not known.
The project developed a greater understanding of the causes / mechanisms of blockage formation in small diameter pipes via a series of practical tests, and will develop guidelines to reduce future blockages. Three elements examined within Phase 1:
- Influence of slack gradients / poor joints.
- Low flows / misuse, and the influence of these factors on blockages.
- Use of inclinometers to ascertain gradients of un-surveyed smaller sewers.
Phase 2 (not included in the price) will further populate the Phase 1 output, with Utility-specific CCTV data from repeat blockage areas.
- Reduced risk of sewer blockages in small diameter pipes and associated sewer flooding
- Cost effective operations / investment in preventing and dealing with sewer blockages, especially repeat blockages
- Augmentation of sewer records, for those sewers where records are incomplete, through use of the inclinometer.