Approximately 5% of blockages are caused by tree roots that ingress into the sewer system, these may result in flooding and pollution. This problem is likely to increase - but what is the best solution? Which tree root barriers methods are effective and in what situations?
The problem of tree root ingress is increasing because new developments tend to be high density and include close-by tree planting. In addition, since the transfer of private drains and sewers, companies now have responsibility for more shallow-laid pipes in high-risk areas such as footways and gardens.
To resolve the problem, the roots must be removed from the pipe. However, root cutting by itself will often only provide a temporary solution leaving a significant long-term maintenance problem. A permanent solution is required for new developments and as a retrofit for existing systems. Installation of root barriers is a potential solution to prevent root intrusion problems. The majority of root barriers control roots by diverting them away from sewers. There are three main types of barriers: traps, inhibitors and deflectors.
This project will assess which are the most effective tree root resistance methods for pipe and chambers and develop guidance for use by developer service managers. To deliver this project WRc will work with IKT, a German institute which has carried out fundamental research on tree root intrusion.
BUSINESS BENEFITS TO CLIENTS
- A reduction in the number of blockages, flooding incidents and pollution due to tree root intrusion and the costs associated with their on-going reactive management.
- Improvement in sewer serviceability as reported to the regulator and reduced customer contacts.
- Review the latest fundamental research on tree root intrusion and the effectiveness of tree root barriers and factors that influence their successful use.
- Engage with suppliers and end-users to identify a number of case study areas where barriers were installed.
- Develop guidance on selection and installation of tree root barriers.
PROJECT OUTPUT AND IMPLEMENTATION
- A guide for developer service managers to use in specifying to developers the beneficial and cost effective use of tree root barriers.
- Update for future editions of Sewers for Adoption.
RELATED WRc WORK
- Tree root damage to sewers: prevention and cure, March 1999
- CP147 Reducing Tree Root Penetration of Sewer Pipe Joints, April 2005
- German guideline on "Trees, underground Pipelines and Sewers", IKT 2013