Project Appreciation and Objectives
In 2008/9 sewer blockages in public sewers resulted in approximately 30,000 internal and external sewer flooding events in England and Wales. The total cost of sewer blockages to water companies is in excess of £20 million per year with an estimated £15 million spent annually on blockage clearance. Maintaining the hydraulic capacity of sewer systems by the removal of silts, sewer debris and FOG is a high priority for sewerage undertakers (SUs), but the current drive to reduce water usage and the transfer of private sewers; increasing the length and type of sewers for which SUs are responsible, will create new challenges. Flow amplification devices are marketed as a low maintenance and cost effective alternative to traditional sewer cleaning practices. Although previously in common use in the UK, the development of sewer jetting technology meant that their use declined. This project will determine the:
- Effectiveness of the devices in reducing accumulations in sewer systems.
- Maintenance requirements of the different flow amplifying devices.
- Economic case for using flow amplification devices in comparison with traditional sewer cleaning practices.
- Performance of different sizes and designs of flow amplifying devices and their suitability for use in the UK.
Benefits to Clients
- Reduced flood risk through frequent flushing of sewers and the removal of material from the sewer.
- Alternatives to reactive clearance of blockages or re-laying of problematic small diameter, former Section 24 and private sewers.
- Informed decisions on the use of flow amplifying devices in the UK sewer system.
- Assess the performance of different types of flow amplifying devices including maintenance requirements.
- Determine the effectiveness of flow amplifying devices in reducing accumulations in sewer systems.
- Assess the influence of the structure of the target sewer on the flow wave generated from the devices.
- Determine the costs of different devices, capital and maintenance, against traditional sewer cleaning practices.
Guidance to assist Sewerage Undertakers in the assessment of alternative approach to sewer cleaning practices which will:
- Provide evidence/confidence of the benefits, robustness and effectiveness of flow amplification devices.
- Establish if adverse effects occur with different amplification devices.
- Support future planning and investment decisions in sewer maintenance.
Related WRc Work
- Research into the impact of low flows on the performance of sewers and drains.
- Evaluation of proprietary flow amplifying devices.