Drainage systems need to be protected from blockage due to debris and coarse sediment, and vegetated systems need to be protected from toxic materials that could damage the vegetation. The downstream water environment that the systems discharge to also needs to be protected from pollutants. This function is currently largely delivered by gully pots and oil interceptors.
When gully pots become blocked due to lack of maintenance, flooding is exacerbated and presents risk to people, property, and infrastructure.
Gully pots can also create a reservoir of contaminated sediment and a source of polluted liquor that, if improperly managed or when hit by intense storms, can lead to high-level polluting discharges into sewers and watercourses.
Similarly, oil interceptors create a reservoir of contaminated sediment and immiscible liquids and need to be properly maintained to avoid these being released to the downstream system.
Preliminary treatment components are under increasing pressure due to urbanisation and the growing frequency and severity of storms driven by climate change, and the capacity of resource constrained local authorities to manage them.
The costs associated with damage caused from failing drainage assets and subsequent flooding is likely to exceed the cost of well-planned preventative measures designed to maintain optimal asset performance, as supported by this guidance.
From a new development and retrofit perspective, there now exists a wide range of technologies and techniques to better manage rainwater for improved flood-risk and water quality outcomes, while resolving some of the maintenance challenges associated with traditional methods.
Without challenging the efficacy of current practice, the UK risks continued investment in drainage assets that can no longer be seen as good practice, missing the opportunity to invest in other technologies and techniques (e.g., Sustainable Drainage Systems (SuDS)) that can deliver greater benefits.
The overall aim of the project is to demonstrate and highlight good practice in the design, use, and maintenance of preliminary treatment features to improve asset performance, reduce flood risk, and help limit levels of pollution entering the UK drainage networks and watercourses. It will also explore guidance on the treatment of waste collected from preliminary treatment, and the interlinkages between preliminary treatment, SuDS, and other drainage systems.
Status
Recruitment of the research contractor via competitive tender has begun.
Funders
Buro Happold; Forest Group; Green Rhino; Kier; Marshalls; Milestone Infrastructure; NADC (National Association of Drainage Contractors); National Highways; Rees Jeffreys Road fund; Stormwater Shepherds; Hydro International; WSP; Network Rail; Defra
Further information
If you are interested in this topic, please contact Adrien Baudrimont or Rob Mitton.