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).However 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.
There are commercially available technologies currently on the market to deal with irregular flows and these offer the potential benefit of reducing blockages in the sewer system. Flow amplification devices are one of these, marketed as a low maintenance and cost effective alternative to traditional sewer cleaning practices but there are concerns about their effectiveness. The main objective of this project is to evaluate the performance of flow amplification devices in real systems and determine under what circumstances they provide a cost beneficial alternative to conventional practices.
Business Benefits to Clients
- Reduced flood risk through frequent flushing of sewers and the removal of material from the sewer.
- More effective and cost beneficial 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.
- Quantify 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.
- Quantify the costs of different devices, capital and maintenance, against traditional sewer cleaning practices.
Project Output and Implementation
Guidance to assist Sewerage Undertakers in the assessment of alternative approaches to sewer cleaning practices which will:
- Provide evidence/confidence of the benefits, robustness and effectiveness of flow amplification devices so that they can be adopted where appropriate by sewer operations managers.
- Give guidance on effective application of the technology.
- Support future planning and Capex/Opex 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.