Utility Week

14 | FEBRUARY 2023 | UTILITY WEEK Water water companies – and some administered through the Environment Agency. Compared with ood defence schemes at rivers and coastal locations, surface water ooding schemes tend to be smaller scale and spread across a wider catchment area, Boorman explains, which makes it di• cult in terms of the Environment Agency allocat- ing and distributing money. Collaboration is essential here, and via a pilot by the mayor SuDS are being added where possible a• er utilities have dug up a road. "We want to use these as opportunities to build back better and green with permeable surfaces," Boorman says. The approach has the potential to cut delivery costs by 25%, as a project in En‡ eld where SuDS were added concurrently to streetworks shows. "We're aligning infrastructure work with poten- tial SuDS schemes by local authorities to reduce the overall cost of delivering SuDS, which would be fantastic to help funding go further." Essentially it will take countless small pockets of activity across the city to reach Thames Water's estimation of needing 7,200 hectares by 2050. Thames' strategy supports borough coun- cils to include SuDS in routine work, espe- cially in high risk areas. "We are rethinking our approach to rain- fall," says Alex Nickson, wastewater systems strategy manager at Thames Water. "Green infrastructure solutions, such as street trees and raingardens, are now the central ele- ment of our long-term plan to manage sur- face water ood risk in the capital." The company "strongly supports" the NIC's call to tackle the loss of green spaces and manage the impacts of new develop- ments using existing legislation. Thames' ambition to drain 50 Hyde Parks- worth of impermeable areas to sustainable drainage by 2050 is a tall ask compared with the amount delivered in recent years. Nick- son says it will take a total shi• in thinking. "This will be delivered through changing our approach to implementing SuDS, moving from a reactive, opportunistic approach to a target-driven outcome focused mentality, achieved through improving new develop- ments, retro‡ tting existing urban areas and encouraging and incentivising Londoners to unwind the urban creep that has been ena- bled over decades." Gains made with developers Getting ahead of the curve, prior to Sched- ule 3 being approved, United Utilities (UU) has been working with developers across the North West on incentive schemes for includ- ing SuDS such as o˜ ering a 90% reduction of infrastructure charges for not connecting into the sewer network. Samuel Fox, network strategy and plan- ning manager at UU, explains: "It's not about inhibiting growth, but how can we support that growth without ood risks." He says the company is looking at incen- tivisation and adoption of SuDS as well as best approaches to maintenance once they are installed. "We're excited about the opportunity to start investing outside of our traditional below-ground asset base but we're very mindful of the a˜ ordability challenge and making sure we deliver things that actually address the core service we provide for cus- tomers while also delivering things that have wider multi-capital bene‡ ts." Another challenge the company is looking at is managing unpermitted developments, such as the expansion of impermeable surfaces like driveways and covering domestic garden spaces. The NIC called for a clarity and focus from govern- ment on planning requirements for people undertaking projects in order to tighten up local authorityžrules. To address the challenge at domestic level, UU is exploring property level sepa- ration on streets where the surface water is connected to a combined sewer. It wants to disconnect the surface water out ows and reroute them into SuDS. "One challenge we have is on a street that is completely connected to the combined system, you need 100% of the properties to buy into that disconnection. Otherwise you leave a path for all the rainwater to still enter the system. We're running trials to under- stand customer engagement and willingness to participate." This could be a constructed wetland or trees planted with a retention pond or space to collect rainwater to channel it away from the sewer. "There are di˜ erent options in terms of disconnection at property level, or dis- connection within the public sewer itself. We're exploring the cost bene‡ t and the disruption." On a˜ ordability, he says UU is looking at alternative routes of investment that would deliver multiple bene‡ ts on top of alleviat- ing ood risk. "SuDS have a core part to play with regards to enhancing the aesthetic appeal of an area. They provide well-being bene‡ ts, cooling urbanised areas, carbon sequestration, all of those really positive things from sustainable drainage." "Surface water management and SuDS have not necessarily been lost in the con- versation around spill reduction, but there's obviously been a heavy focus on that. We want to make sure we don't disconnect those two things." Ultimately, the company is looking at spill reduction and surface water management through SuDS in tandem through its rainwa- ter management strategy, which recognises the value of every drop that falls. Water companies have been working to overcome the hurdles long before govern- ment gave the green light to SuDs. Now blue- green infrastructure can develop at pace, with developers and local authorities work- ing alongside the water industry and other stakeholders to bring natural solutions to mitigate climate change. It remains to be seen how the government chooses to apply Schedule 3, but mandating SuDS will force a rethink of managing sur- face water, which cannot come soon enough. Ruth Williams, water correspondent continued from previous page Analysis London mayor Sadiq Khan is championing an initiative to get the city's boroughs, water company and other stakeholders to come up with a joint plan for implementing SuDS. Thames Water estimates that 7,200 hectares of SuDS are needed by 2050.

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