Project Appreciation and Objectives
There were over 200,000 sewer blockages on public sewers and lateral drains in the United Kingdom in 2009. A significant proportion of these blockages caused either internal flooding or an external pollution event. These problems are no longer regarded as acceptable by the public, complaints relating to sewer blockages are the largest single cause of unwanted customer contacts (i.e. high SIM scores) in wastewater services.
There are a number of ways that the number of blockage incidents can be reduced, including proactive intervention and to fully implement this approach, there is still a need to better understand the cause of blockages.
In project CP424, WRc, in association with the University of Exeter, developed and undertook an initial calibration of a Blockage cause diagnosis tool to predict the likelihood of a blockage in a sewer. This tool, which is based on attributes of the sewer and the properties served, allows the investigator to identify the cause of the blockages and assess the impact/cost-benefits of various interventions.
This project will test the tool in a series of practical trials in a wide range catchments where blockages are a significant problem. These trials will allow users to gain confidence in the use of the tool, help determine its effectiveness and improve calibration and therefore its accuracy. A risk-based element, allowing the user to take into account the likelihood of internal or external flooding and environmental pollution will be added to the tool.
Business Benefits to Clients
- A proven methodology to assess where a proactive blockage intervention policy would be most beneficial.
- Greater confidence and experience in using the tool leading to better selection of the most appropriate intervention methods.
- Reduced numbers of blockages, flooding and environmental pollution incidents and reduced number of unwanted customer contacts and improved customer reputation.
- Associated operational cost savings.
- Trial the blockage tool in a wide range of blockage prone catchments (age, catchment type, location and demographics), to assess both its accuracy and ease of use.
- Improve the accuracy of the tool through further calibration and validation, for example the effect of hot food establishments on fats/oils/grease related blockages.
- Introduce new features into the tool, for example certain demographic factors such as property ownership.
- Introduce a facility for the user to include consequence of blockage into the model (e.g. internal or external flooding and environmental pollution).
Project Output and Implementation
An improved blockage cause diagnosis tool, including a new risk based element and guidance on its use. This will be used by sewerage strategy managers and practitioners in sewerage operations to implement a proactive intervention policy and thus reap the associated benefits.
Related WRc Work
- Development of a Blockage - Cause Diagnosis Tool, CP424, 2011 -2012
- Effect of reduced water usage on sewer solids movement, CP367, 2009
- Blockages in small diameter pipes, CP283/283a, 2007