Stuart Fleming, a director at Will Rudd Edinburgh, explains how smarter drainage design can help to unlock urban hotel developments
AS demand for high-quality hotels continues to rise across Scotland’s cities, new developments are increasingly taking place within tight, complex and heritage-rich sites. In Edinburgh, where opportunities for large new-build plots are limited, many hotel projects now involve the redevelopment or conversion of existing buildings. These sites are often defined by constrained footprints, extensive hard surfaces and historic drainage connections. Conditions that pose significant challenges for sustainable water management.
At Will Rudd, we are seeing drainage strategy emerge as one of the most decisive factors in determining the viability of urban redevelopment projects. As climate change drives more intense storm events and adds strain to combined sewer systems, drainage can no longer be treated as an afterthought. It must be considered from the earliest design stages to ensure developments are both deliverable and resilient.
Understanding the urban drainage challenge
A recent project at the Waldorf Astoria in Edinburgh demonstrates how these challenges play out in practice. The site, a Grade A listed building in the heart of the city, offered virtually no natural ground or soft landscaping, and every surface, from roofs to car parks, was impermeable. Historically, all rainfall was discharged directly into the combined sewer network, a common but unsustainable approach that places increasing pressure on urban infrastructure.
The project involved a new 96-room extension on a fully brownfield site, served by a 990mm combined sewer running through the south of the plot. The car park was fully hardstanding and discharged untreated surface water into the combined sewer in Rutland Street. With Scotland’s wastewater treatment works already near capacity, this model is no longer viable. The engineering challenge was to deliver betterment, reducing the rate and volume of water entering the system, without compromising on commercial viability or the site’s heritage.
Designing for betterment
We began with a comprehensive site appraisal and early drainage strategy to identify opportunities for attenuation and flow control within the constrained footprint. Working closely with landscape architects, we explored how green infrastructure could offset the lack of permeable surfaces. A substantial green roof was incorporated into the design, slowing surface water flow, reducing peak discharge and providing wider benefits such as insulation, biodiversity and visual amenity. The roof was designed to accommodate a one-in-200-year storm event with a 40% allowance for climate change, ensuring long-term resilience.
This achieved a significant reduction in post-development discharge – cutting the flow rate to a quarter of its original level, from 16.2 litres per second down to 3.0 litres per second. This aligns with City of Edinburgh Council’s standard and all rainfall up to a one-in-200-year event is now attenuated on-site, ensuring no surface flooding, even under climate change conditions.
Other key features include permeable paving, filter trenches and soft landscaping zones that capture and treat surface water through infiltration and evapotranspiration. The stone-filled subbase beneath the car park provides storage, allowing runoff to be released gradually. Together, these measures form a SuDS “management train” that meets both Scottish Water and SEPA water quality and quantity requirements.
Navigating policy and collaboration
Delivering this improvement required close alignment with policy and early engagement with stakeholders. Scottish Water’s preferred options for sustainable drainage systems (SuDS) set the framework for our approach. For most heritage or urban sites, infiltration systems are not feasible due to space or ground conditions. At the Waldorf Astoria, we evaluated all five options under Scottish Water’s Surface Water Policy, confirming that draining to the combined sewer (Option 5) was the only viable route, but crucially, with a betterment strategy built in through attenuation and flow control.
Equally important is early dialogue with consultees such as the City of Edinburgh Council’s flooding team and Scottish Water. By submitting a Surface Water Management Plan and Flood Risk Assessment at the planning stage, we ensured the development principles were sound before detailed design began. This proactive approach secured permissions for additional foul flows from the new bedrooms while demonstrating a substantial reduction in surface water discharge.
Negotiating the balance between compliance, sustainability and commercial reality is where engineering adds real value. The aim is to meet policy objectives, deliver betterment for the city’s infrastructure and align with the client’s programme and budget.
Sustainable drainage as an enabler
The Waldorf Astoria project is a clear example of how a considered drainage strategy can unlock development potential that might otherwise seem unviable. Through creative engineering, collaborative design and a commitment to sustainability, it is possible to achieve meaningful environmental gains even within the tightest urban footprints.
A robust maintenance framework is now in place under the site’s deed of conditions. Routine inspection, sediment clearance and system integrity checks will ensure the drainage network performs as designed throughout its lifecycle.
More broadly, sustainable drainage design is reshaping the future of urban redevelopment. As we adapt to the challenges of climate change, drainage will increasingly define what can, and cannot, be built in our city centres. For the hotel sector, where heritage preservation, guest experience and operational performance must align, early engagement with drainage design is not only good practice, it is essential.
At Will Rudd, our philosophy is simple: get the principles right first. By addressing drainage strategy at the outset, we help clients deliver developments that are technically compliant and future-proofed against the growing demands on shared urban infrastructure.
Sustainable drainage is no longer just an environmental consideration; it is a cornerstone of resilient, viable and successful city centre regeneration.
