2 Stillhouse Lane, Bristol
The proposed development at 2 Stillhouse Lane involves the partial demolition of a vacant commercial workshop and the construction of a three-storey residential building, comprising two maisonettes and one self-contained flat. The site lies within Flood Zone 2 and is exposed to multiple flood sources, requiring a comprehensive flood risk assessment (FRA) and a robust Sustainable Drainage System (SuDS) strategy.
Flood Risk Context
The site was found to be subject to:
Fluvial flooding – High risk
Surface water (pluvial) flooding – High risk
Sewer flooding – Medium risk
Flooding from artificial sources (e.g. reservoirs) – Medium risk
Groundwater flooding – Low risk
Although located in Flood Zone 2, the proposal does not increase the site’s impermeable area and maintains the original building footprint, ensuring no net increase in flood risk to the site or surrounding areas.
Sequential and Exception Test Justification
While technically exempt from the Sequential Test due to its classification as a change of use and replacement building, the project was accompanied by a detailed Sequential Test Assessment to support policy compliance. The test concluded that:
No alternative lower-risk sites were appropriate.
Regeneration benefits justified limiting the search area to the site alone.
The flood risk exposure of future users was minimised through elevated habitable spaces and resilient design.
The development passed the Exception Test by incorporating sustainability benefits (e.g. green infrastructure) and ensuring safety for its lifetime without increasing flood risk elsewhere.
SuDS Strategy and Surface Water Management
Given the site's tight urban setting and clayey soil conditions, infiltration techniques and permeable paving were deemed unfeasible. Instead, a targeted SuDS approach was adopted:
Rainwater Planter (225L): Positioned on a terrace to intercept runoff from the flat roof and support water reuse through plant irrigation.
Runoff Reduction: Despite no change in impermeable area (145m²), post-development runoff rates were reduced by up to 5% due to source control features.
Compliance with the SuDS Hierarchy:
Reuse at source: Implemented
Infiltration: Not feasible due to soil and space limitations
Discharge to watercourse: Not applicable
Discharge to surface water sewer: Existing connection retained
Discharge to combined sewer: Avoided
Design Standard: Drainage network designed to accommodate a 1 in 100-year event plus 40% climate change allowance.
Exceedance Management: Overland flows will be safely contained within site boundaries.
Mitigation and Resilience Measures
The following flood resilience and resistance features were incorporated:
Finished Floor Levels raised 600mm above the design flood level
Flood-resistant materials, sealed utility entry points, and raised electrical sockets
Non-return valves on foul water outlets
Emergency egress via a designated dry route (7-minute walk to Victoria Park)
No habitable rooms at ground floor level
Outcome
The FRA and SuDS Strategy demonstrated that the proposed development would remain safe throughout its lifetime, support the regeneration of an underutilised site, and contribute positively to Bristol's urban fabric without increasing flood risk. Bristol City Council is expected to support the application, recognising both its technical compliance and wider sustainability benefits.
Planning portal: https://pa.bristol.gov.uk/online-applications/applicationDetails.do?activeTab=documents&keyVal=T3CMS7DNGIE00