Flood Risk Assessment and SuDS Strategy — Condition Discharged, Kensington & Chelsea

Flood Risk Assessment and SuDS Strategy — Planning Conditions Discharged, Kensington & Chelsea
Location: 2 Donne Place, Royal Borough of Kensington and Chelsea | Services: Flood Risk Assessment, SuDS Strategy, Planning Condition Discharge

Project Background
Planning conditions relating to flood risk and surface water management are increasingly common on residential extension projects across London, particularly in boroughs with a strong policy emphasis on sustainable drainage. At 2 Donne Place in the Royal Borough of Kensington and Chelsea, a proposed single-storey rear and side extension triggered conditions requiring both a Flood Risk Assessment and a SuDS Strategy before works could commence.
The two conditions needed to be addressed together — flood risk findings directly inform drainage design, and the LPA needed to see both elements resolved in a single, coherent technical submission.

Flood Risk Assessment
We carried out a comprehensive site-specific flood risk assessment covering all relevant flood sources: fluvial, surface water, and sewer flooding. Each source was assessed in turn, with findings referenced against Environment Agency flood mapping, Thames Water sewer records, and relevant SFRA data for the Royal Borough.
Where flood risk was identified, design recommendations were specified to ensure the proposed extension remained protected. This included flood resistance and resilience measures appropriate to the site's risk profile, providing the LPA with confidence that future occupants would not be exposed to unacceptable levels of flood risk as a result of the development.

SuDS Strategy
With the flood risk picture established, we developed a SuDS Strategy targeting the 50% betterment in peak discharge rates required under Local Plan Policy CE2(g). Runoff calculations were prepared for both existing and proposed conditions, incorporating climate change allowances and all relevant inflow sources to ensure the assessment was complete and defensible.
The drainage solution proposed a combination of rainwater planters and permeable paving — two complementary measures well-suited to a constrained residential plot in a dense urban setting. Rainwater planters provide above-ground attenuation with associated biodiversity and amenity value; permeable paving manages runoff at source across hardstanding areas, reducing the volume and rate of water entering the sewer system.
Full technical detail was provided for each SuDS component: location, specification, attenuation capacity, structural integrity, operational strategy, and long-term maintenance responsibilities. Drainage layout plans and section drawings illustrated surface water routing from the proposed extension through the SuDS features and into the wider drainage system.

Outcome
The Local Planning Authority discharged both conditions in full with no additional comments. By addressing flood risk and drainage design together in a single coordinated submission, the client avoided the delays that commonly arise when these elements are treated separately or submitted piecemeal. Development was able to proceed to construction on programme.