Flood Risk Assessment and SuDS Strategy — Two New Dwellings Following Permission in Principle, Shinfield
We prepared a Flood Risk Assessment and SuDS Strategy for two three-bedroom semi-detached dwellings on land adjacent to 1 Ilbury Close, Shinfield, Wokingham, RG2 9DE — a Flood Zone 1 garden-land infill plot granted Permission in Principle under application 261486 in July 2026 — on behalf of Cameron Jones Planning Ltd. Fluvial, tidal, groundwater and artificial-source risks are all low; surface water risk is medium on a plot that is soft landscaped throughout and will be substantially built over, and sewer risk is medium on a network under pressure from the pace of local development. The strategy follows the drainage hierarchy from the top, with infiltration as the primary disposal route, permeable surfacing, water butts and retained soft landscape as source control, and residual discharge attenuated to a controlled rate for the 1-in-100-year event with a 40% climate change allowance.
Flood Risk Assessment and SuDS Strategy for Two New Dwellings Following Permission in Principle, Shinfield
Location: Land adjacent to 1 Ilbury Close, Shinfield, Wokingham, RG2 9DE | Client: Cameron Jones Planning Ltd | Services: Flood Risk Assessment; SuDS Strategy
Permission in Principle Settles the Use, Not the Drainage
Permission in Principle was granted for residential development on land adjacent to the existing dwelling at 1 Ilbury Close under application 261486 in July 2026. That consent establishes that housing is acceptable here in land use terms. It resolves nothing technical. The technical matters fall to the subsequent Technical Details Consent, and flood risk and surface water drainage are among the first that a local planning authority will want to see addressed.
We were appointed by Cameron Jones Planning Ltd to prepare the Flood Risk Assessment and SuDS Strategy at this stage rather than holding them back to the Technical Details submission. On a two-dwelling infill plot that is a practical decision, not a procedural one. The drainage design has a direct bearing on the layout: where the permeable surfacing goes, how much soft landscape is retained, and where any attenuation feature sits. Resolving it before the detailed layout is fixed avoids retrofitting drainage into a plan that has no room left for it.
The proposal is the construction of two three-bedroom semi-detached dwellings on garden land adjacent to the existing dwelling at 1 Ilbury Close, Shinfield, Wokingham, RG2 9DE.
Site Characteristics and Flood Risk Profile
Shinfield sits south of Reading in a setting of former agricultural land now under substantial residential development. The plot is a garden-land infill adjacent to an existing dwelling, soft landscaped across its whole area in the existing arrangement.
We drew on the Environment Agency Flood Map for Planning, the Risk of Flooding from Surface Water mapping, BGS geological mapping, LiDAR topographic data and the Wokingham Borough Council Strategic Flood Risk Assessment. The site lies within Flood Zone 1, land assessed as having a low probability of flooding from rivers and the sea.
Fluvial and tidal risk are low. The site lies well outside the 1-in-100-year plus climate change extent and there is no watercourse in the immediate vicinity. Groundwater risk is low. Risk from artificial sources is low, the site sitting outside any modelled reservoir inundation extent.
Surface water risk is medium. On a plot that is currently soft landscaped and will be substantially built over, this is the source that the development itself has the greatest capacity to worsen, and it is accordingly the focus of the strategy.
Sewer flooding risk is medium, reflecting recorded incidents in the surrounding area and, in this part of Wokingham, a network under pressure from the pace of residential development. That rating carries a direct design consequence: discharge to the public sewer cannot be assumed to be available at an unrestricted rate, and the strategy is built so that it does not depend on one.
Surface Water Management Strategy
The strategy follows the drainage hierarchy from the top. Infiltration is assessed first and, where soil conditions allow, adopted as the primary disposal route. The low groundwater rating is favourable in this respect, in contrast to many of the Thames valley sites where a shallow water table rules infiltration out at the first step.
Source control sits ahead of any attenuation feature, so that the volume reaching it has already been reduced: permeable surfacing to driveways and parking, water butts to each dwelling, and soft landscape retained across the remainder of each plot. Where residual discharge is required it is attenuated and released at a controlled rate, so that the developed plot does not increase peak flows into a sewer network that already carries a medium flood risk rating.
The network is designed to the 1-in-100-year storm event with a 40% allowance for climate change.
Outcome
The assessment demonstrated that the two new dwellings are at an acceptable level of flood risk for their lifetime and that flood risk at the site and at surrounding sites is not increased. Wokingham Borough Council has the flood risk and drainage evidence in place ahead of the Technical Details Consent, on a plot where the surface water and sewer ratings, rather than the flood zone, are what the design has to answer.