Rainwater Management

United Utilities (UU) wishes to engage the market to support the delivery of Rainwater Management schemes across the North West of England. The Environment Act and subsequent Storm Overflow Discharge Reduction Plan (SODRP) have introduced a statutory requirement to significantly reduce the operation of storm overflows, with all storm overflows expected to spill no more than ten times per year by 2050. Approximately 54% of United Utilities' wastewater network is a combined sewer system, conveying both surface water and wastewater to Wastewater Treatment Works (WwTWs) or Combined Sewer Overflows (CSOs) prior to discharge to the environment. This framework will enable United Utilities to appoint Contractors to deliver Rainwater Management solutions that reduce the volume of surface water entering the combined sewer network. Through the implementation of nature-based and sustainable drainage interventions, the framework aims to mitigate the impacts of storm overflows, improve network resilience, and contribute to the achievement of regulatory and environmental objectives. United Utilities’ (UU) Rainwater Management strategy is founded on Sustainable Drainage principles, which prioritise the capture, reuse and management of rainwater as close as possible to where it falls. The strategy promotes the use of surface conveyance, infiltration, disconnection and attenuation to slow the movement of water through the catchment and reduce pressure on the wastewater network. This approach, combined with measures to improve water efficiency, creates additional capacity within wastewater catchments, reduces demand for potable water, and maximises value by delivering wider environmental, social and economic benefits through the creation of blue-green infrastructure. By increasing the use of Rainwater Management interventions, UU can reduce its reliance on traditional, carbon-intensive engineering solutions, such as underground storage tanks, while delivering best value outcomes for customers and the environment. Whilst many of the individual interventions are well-established and proven, the scale and pace of delivery proposed by UU is unprecedented within the sector. The opportunity lies in developing and deploying these solutions at scale, working collaboratively with customers, businesses, Local Authorities, and other key stakeholders to drive widescale delivery and maximise catchment-wide benefits. The current Rainwater Management Programme identifies approximately 6,500 interventions across the United Utilities network area. However, Bidders should note that the programme remains subject to ongoing development and refinement may include up to 10,000 interventions over the framework term. Interventions will be delivered across the five county areas served by United Utilities: Cumbria, Lancashire, Cheshire, Greater Manchester and Merseyside. Particular focus is anticipated within Greater Manchester and Merseyside over AMP8, reflecting the strategic importance of these areas, the presence of Combined Authorities, and the objectives set out within their respective Integrated Water Management Plans (IWMPs). Rainwater Management Intervention Types Attenuation Pond: holding water body, suitable in large natural spaces only Bio-retention: pollution control incorporated into intervention design Blue Roof: smart water storage to catch rainwater and slow the return period Disconnection: surface water systems or extraneous rainwater from the combined network to a more suitable receiver e.g. water course. Downpipe Disconnection: from residential and business buildings, e.g. butt rainwater planter. Filter Drain: trench filled with gravel, water infiltrates to ground Green roofs: water retaining layer beneath a growing medium and planting for additional benefits e.g. air quality, biodiversity. Natural Flood Management (NFM): landscape solutions to manage uplands to retain rainwater where it falls e.g. leaky dams, catchment planting Permeable Paving: water infiltrates to ground or stored/ attenuated underground Rain Garden: surface planting, water infiltrates to ground or stored/ attenuated underground Soakaway: excavation filled with gravel and landscaped. Water infiltrates to ground Swale: shallow wide channel to catch, slow the flow or infiltrate water to ground. Can be wet and/ or dry Tree Pit: underground system combining urban tree planting with drainage that captures stormwater Landscape Maintenance & Management: services to undertake appropriate landscape maintenance such as mowing, watering, visual inspections, re-planting, silt removal. Disconnections Contractors will be responsible for the Design and Build of low complexity surface water disconnection works, where existing surface water pipes connected to the combined sewer network will be diverted to a more suitable receiving system. This may include connection to existing surface water sewers, or discharge via Rainwater Interventions such as rain gardens, attenuation ponds