Water & Wastewater Treatment Magazine
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www.wwtonline.co.uk | WWT | APRIL 2019 | 21 ment of SuDS and help to explain why England lags so far behind Scotland in terms of implementation - unless authorities understand how to assess planning applications and developers how to design appropriate SuDS systems, these vital solutions could continue to be neglected. SuDS advice However, the issue may be more one of lack of under- standing of where to obtain help. Expert guidance is available from the Construc- tion Industry Research and Information Association (CIRIA) and its specialist SuDS platform Susdrain in the form of both SuDS fact sheets and CIRIA's highly-regarded SuDS manual. The water industry has also produced guidance, for example, Anglian Water's own SuDS adoption manual. Arguments over respon- sibility for maintenance have also posed a significant barrier to implementation in England - in Scotland, where responsibility was clarified early on, SuDS have been ex- tensively adopted. Again, this aspect is now made clear in the water industry guidance. Helpful technologies Exemplar technologies are also now available to ease the transition to this type of approach. These include Jacopa's HydroStyx solution, which regulates flows within trunk sewers to attenuate peak flows and utilise poten- tial storage volume to reduce flood risk. HydroStyx is a cost-effec- tive, autonomous wastewater control solution, designed to minimise inner-city flood risks, which forms part of the CENTAUR (Cost Effective Neural Technique to Alleviate Urban Flood Risk) project. This was developed and tested at the University of Sheffield, and the first pilot plants were installed in Coimbra (Portu- gal) and Toulouse (France) to protect historically valuable parts of the old towns. Many real-time control (RTC) projects focus research on very large networks, such as complete sewerage systems that include complex sensor networks connected to a central control. These in turn are run by costly and complex calibrated hydrodynamic modeling tools and radar sweep technology. CENTAUR is a cost-effective solution that uses data-driven approaches to enable real- time control strategies for the use of local channel storage volumes. Sophisticated com- puter-aided techniques are used with specially designed outflow regulators to reduce the risk of flooding. CENTAUR is autonomous, decentral- ised, and does not require a hydrodynamic model. The system learns; it is flexible and adjusts itself over time to the type of changes in runoff that can result from climate change, land use or popula- tion growth. The reduced investment costs and minimal infrastruc- ture required mean the system can be gradually installed in high-risk locations so that water companies and local authorities can tailor their approach to local conditions. The surveillance and control system enables autonomous control of the flow rates and monitoring of the available channel volumes. CENTAUR utilises the Jacopa Steinhardt HydroStyx discharge brake, with its in- tegrated emergency overflow. This non-powered mechani- cal sewer system manage- ment tool can be installed in the sha's of large-diameter trunk sewer systems before combined sewer overflows (CSOs) that tend to breach their consents. The stainless-steel cascade arrangement retains water in the sewer or a stretch of sewer network, using unused or partially-used volume and delaying the outflow of water into the receiving structure. The HydroStyx is available either as a weir brake, which holds back discharges at a fixed surcharge level, or as a swinging brake: two swing gate elements that retain water to a designed attenua- tion volume. Using existing entry chambers, both types of HydroStyx attenuate the flow as it passes from section to section, taking the peak out of the storm surge. Such technology-based solu- tions fit well into the overall SuDS framework, as attenuat- ing storm flows is at the heart of both engineered and natu- ral solutions such as swales, detention ponds, permeable paving, subsurface attenua- tion crates, green roofs and related technologies such as the HydroGuard sewer flush- ing system, which prevents sediment build-up in sewers. Attenuation of storm flows in this way, by utilising the unused storage within the existing volume of the sewerage system, can prevent flash flooding and enable other SuDS solutions to be designed to be smaller, and therefore less costly and space consuming. The HydroStyx also closely matches the basic ethos of SuDS, of attenuat- ing storm flows to eliminate the sharp peaks caused by excessive construction of hard surfaces on flood plains and other urban areas. SuDS benefits The benefits that SuDS bring are worth the effort of iden- tifying sources of guidance and clarifying maintenance responsibilities. They include not only flow attenuation but also surface and groundwater quality improvements and reduction of operational and embodied carbon. They can also enable headroom for ex- tra urban growth and reduce peak flows to treatment works. The systems also help to resolve some of the issues highlighted in the LI/CIC re- port findings and can be used in tandem with other SuDS so- lutions to help prevent storm- water flooding. They provide cost-effective solutions that are simple to install, require no additional footprint, and that empower owners to take control of increasingly acute climate change-related issues. Hear more about SuDS at WWT's Sustainable Drainage Conference on May 1st: event.wwtonline.co.uk/suds A HydroStyx system being installed