Inglemere Road

Project: 27 Inglemere Road
Location: Inglemere Road, Forest Hill, London
Client: Rapeed Design
Services: Transport Planning, Drainage Engineering

Inglemere Road 3d representation

The Project

Early in 2020 the Calibro team’s transport planning and drainage expertise was called upon by Newsteer Real Estate Advisors acting for Rapeed Design. It was in support of a planning application for a proposed development comprising the demolition of a former care home that had been vacant since 2015; and the construction of a part three/part four storey building to provide 20 residential flats, including three affordable rent units. 

The Problem

The site had lay derelict for several years and attempts to find new care home operators were unsuccessful, so the client needed to find an alternative use for the site. After considering several options and following a process of due diligence, the decision was taken to apply for planning permission to demolish the existing care home to make way for a block of modern apartments. 

However, the proposed development would increase the impermeable area on the site by around 10%, which could represent a risk of flooding downstream from surface water runoff if the proposals weren’t mitigated. Our desktop analysis indicated that disposal of surface water through infiltration would be unlikely given the site was underlain by London Clay, which has a low potential for infiltration. What’s more, very limited space above ground meant there were no significant opportunities to incorporate infiltration without reducing the development potential of the site. 

Additionally, it was impossible to dispose of surface water runoff to existing surface water bodies, as the nearest watercourse was located around 1.2 km to the east of the site, making connection to it unviable. 

The limited space within the site also meant the scheme was unable to provide a policy-compliant level of car parking and was therefore reliant on adjoining streets to accommodate the balance in parking demand (although it wasn’t clear that there was sufficient capacity in surrounding streets to safely accommodate this additional requirement).

The Conclusion

Despite clarifications sought by the Council during the determination period, our experts were able to swiftly defend the commercial approaches taken across our assessments. This enabled positive consultation responses to be provided in a timely fashion, and avoiding delay to the project.  

Ultimately, the Council’s planning committee resolved to grant planning permission for the development in September 2021, unlocking the full potential of the site. 

The Solution

The drainage solution required a connection to be made to the public sewer system which is managed by Thames Water, utilising an existing combined sewer located in Inglemere Road. Restricted peak discharge rates were controlled to greenfield runoff rates via a flow control device linked to underground cellular storage tanks. 

To minimise the amount of surface water needing disposal via the combined sewer, we proposed to implement rainwater harvesting and sustainable drainage systems to intercept and control water quality. Permeable paving was also specified for the parking areas, with a comprehensive tree planting scheme within the site encouraged too.  

To address the car parking issue, we undertook car park beat surveys across weekdays. These took place during the height of the Covid-19 pandemic (during the first lockdown), and we were able to argue successfully that the results represented a worst-case assessment since the majority of local residents would be at home throughout the day and this reduced the potential for spaces to become available at different times during the day. 

Our analysis of car parking in the area demonstrated that the potential parking demand created by the development that was not met by on-site parking provision, could be comfortably accommodated on surrounding roads without impacting on the safety or operation of the highway. 

Calibro has not only been able to identify and present clear and compelling strategies for large and complex site promotions – ones that don’t just rely on costly infrastructure improvements – but they also take a very proactive and innovative approach in the way they engage with key stakeholders.

Jonathan Steel
Director (Planning)

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