2020—2025 Sewer Rehabilitation Prioritisation

2020—2025 Sewer Rehabilitation Prioritisation

Purpose of the Project:
To prioritise investment by assessing which of our 30,000km of sewers are most in need of rehabilitation over the next 5 to 10 years.

Project Objectives as linked to our 25 Year Vision:
To maintain our assets for future generations, at the most efficient cost, through:
–––– Real time weather and sewer models which can help us predict flooding and pollution

The Project
We have over 30,000km of sewers in our network and at current investment levels, it would take over 700 years to replace them all. When problems occur on our sewer network, they can cause significant environmental damage as well as inconvenience to customers.
Because our sewer network is so large, we’re working to understand where investment is needed the most, to ensure that our sewers can operate effectively and meet the challenges we’re going to face over the coming decades.
The aim of our Sewer Rehabilitation Prioritisation project was to undertake a strategic assessment of sewers that are most in need of investment between 2020 and 2025.
This will help us to prevent pollution, sewer flooding and improve the environment for our customers.
This has been led by our Wastewater Assets Below Ground Assets Client Team. Using the Sewerage Rehabilitation Manual (SRM) and combining its methodology, a novel approach has been adopted to generate a risk-based scoring matrix for sewers, where risk of failure and its impact is highest and rehabilitation would be most beneficial.
A risk score has been generated for all of Welsh Water’s sewers based on two key factors, likelihood of failure (e.g. sewer condition) and consequence of failure.
Determination of these involved consideration of a number of criteria selected from recommendations within the SRM and numerous academic journals.
The methodology used represents a relatively quick and cost-effective method of assessing rehabilitation need in comparison to previous expensive sewer deterioration modelling, and covers our entire asset base. By constructing its methodology around the SRM strategic rehabilitation planning recommendations it incorporates industry best practice and ensures a consistent approach to asset management. Further work is ongoing to enhance the outcome of this analysis and improve accuracy.

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