Our Projects

We provided a combined Flood Risk Assessment and SuDS Strategy for an office-to-residential conversion in East Sheen, London Borough of Richmond upon Thames. The site sits on London Clay with groundwater flood susceptibility of 75% or higher, immediately ruling out infiltration drainage under the SuDS hierarchy.

Our design centred on a multi-component management train: a 41.5m² sedum green roof, 630 litres of rainwater harvesting storage, 118.8m² of permeable paving, and an 8.9m³ geocellular attenuation tank discharging at a controlled rate to the surface water sewer. Modelled to the 1-in-100-year event with 40% climate change allowance, the scheme achieved an 83% reduction in peak discharge — from 16.63 l/s to 2.84 l/s. Planning permission was granted in full.

We supported the client in discharging a SuDS Strategy condition for a site within a Critical Drainage Area in Richmond. The initial council feedback requested justification for not using infiltration measures and proposed a complex solution involving permeable paving with sub-base attenuation and pumping.

Our revised SuDS Strategy demonstrated that infiltration was unfeasible due to site constraints and groundwater conditions. Instead, we proposed rainwater planters providing 370 litres of above-ground attenuation, improving biodiversity, water quality, and amenity whilst saving the client cost and construction complexity. The condition was discharged with no further comments from the LLFA.

We discharged a pre-commencement SuDS Strategy condition for a ground floor extension at 29 Meredyth Road, Barnes. The submission included full runoff calculations for existing and proposed conditions — demonstrating over 50% reduction in peak discharge in line with Local Plan Policy CE2(g) — along with permeable paving specification, drainage layout plans, and long-term maintenance guidance. The condition was discharged with no further comment, allowing the client to proceed to construction without delay.

We discharged a pre-commencement SuDS Strategy condition for a residential development at 3 Donne Place, Royal Borough of Kensington and Chelsea. The submission demonstrated a 50% reduction in peak discharge in line with Local Plan Policy CE2(g), incorporating climate change allowances, groundwater inflows, rainwater planters, and permeable surfacing. Full construction, operational, and maintenance details were provided alongside drainage layout plans and section drawings. The LPA approved the strategy in full with no further comment.

We prepared a combined Flood Risk Assessment and SuDS Strategy to discharge two pre-commencement planning conditions for a single-storey extension at 2 Donne Place, Royal Borough of Kensington and Chelsea. The FRA assessed all relevant flood sources and specified appropriate resistance and resilience measures. The SuDS Strategy demonstrated 50% betterment in peak discharge in line with Local Plan Policy CE2(g), proposing rainwater planters and permeable paving with full construction and maintenance detail. Both conditions were discharged by the LPA with no further comment.

We prepared a Flood Risk Assessment and SuDS Strategy for a new residential dwelling at 73 Pope's Grove, Twickenham, on behalf of McLaren.Excell. The FRA successfully challenged a council request to raise the finished floor level by 300mm, demonstrating the requirement was not warranted for a Flood Zone 1 site with managed surface water risk. The SuDS Strategy addressed a net increase in impermeable area of 67m² through a green roof, 600 litres of rainwater planter storage, a shallow dry pond, and permeable paving — achieving compliant post-development runoff rates in line with LP 21 and London Plan SI 13. Planning was approved by Richmond Council.

We prepared a Flood Risk Assessment, Sequential Test Assessment, and SuDS Strategy for a Flood Zone 2 regeneration site in Bristol, where fluvial and surface water flood risk were both classified as high. Although technically exempt from the Sequential Test, a full assessment was provided to support policy compliance — concluding that no sequentially preferable sites were available and that the Exception Test was satisfied through sustainability benefits and safe design. Flood resilience measures included a 600mm FFL uplift above design flood level, flood-resistant construction, non-return valves, and a designated dry emergency egress route. A 225-litre rainwater planter achieved up to 5% post-development runoff reduction despite no change in impermeable area. Bristol City Council is expected to support the application.

We prepared a site-specific Flood Risk Assessment for a mixed-use development at Charlton Mill, Hartlebury, Worcestershire — a Flood Zone 3 site with high fluvial, groundwater, and reservoir breach risk. The critical finding was that the built structures sit entirely outside the modelled flood extent for the 1-in-100-year plus climate change event, meaning no compensatory floodplain storage was required and flood risk elsewhere in the catchment would not increase. Groundwater resilience measures were specified including perimeter land drains, sealed ground slabs, construction-phase monitoring, and moisture-resistant materials. A flood evacuation plan was also produced demonstrating a designated dry-route egress from the site. The assessment demonstrated full compliance with NPPF requirements and South Worcestershire Development Plan Policy SWDP 28.

Appointed to support a planning application for a new dwelling at Station Road, Nether Whitacre, we prepared a site-specific FRA for a Flood Zone 1 site where the primary risks lay not in fluvial flooding but in shallow groundwater conditions and reservoir breach mapping. The underlying Sidmouth Mudstone and River Terrace Deposits indicated the potential for groundwater at depth, and the site fell within the EA's modelled reservoir inundation extent. Our assessment addressed both risks through targeted resilience measures — below-ground waterproofing, moisture-resistant construction, sealed service entries, and ground profiling — alongside a verified flood evacuation strategy. The council accepted the FRA without further comment.

We prepared a site-specific Flood Risk Assessment for the full demolition and reconstruction of a dwelling at Whichford Mill, Warwickshire — a brownfield site within Flood Zone 3, bounded by the River Stout. Despite the high-risk flood zone classification, detailed analysis of Environment Agency flood modelling and LiDAR topographic data confirmed that the proposed building footprint sat outside the 1-in-100-year plus climate change design flood extent. Sequential and Exception Tests were not required under NPPF paragraph 93 given the small-scale rural development classification. Flood resilience measures, surface water management, and a flood evacuation plan were specified to address residual risk and demonstrate lifetime safety for future occupants.

We undertook a full air quality assessment for the conversion of 21–25 Beehive Place, Brixton, from educational use to three residential dwellings — a site within Lambeth's AQMA and one of five designated Air Quality Focus Areas in the borough. The assessment covered construction dust risk, operational phase screening, and Air Quality Neutral compliance against London Plan Policy SI1 transport and building emissions benchmarks. A car-free designation and fully electric heating and hot water systems eliminated on-site combustion emissions entirely. Active measures including HEPA filtration, living walls, and pollution-tolerant vegetation pushed the scheme beyond Air Quality Neutral to Air Quality Positive status, whilst a comprehensive resident protection strategy — positive input ventilation, strategic room positioning, and enhanced glazing — addressed exposure to existing local pollution levels.

We prepared an integrated Air Quality Assessment and Flood Risk Assessment for the installation of an emergency diesel generator at a high-rise residential development in West Bridgford, Nottingham — required under Building Regulations for firefighting lift backup power. The site sits within Flood Zone 3 adjacent to the River Trent, with high groundwater and reservoir breach risk, and borders an area with a history of AQMA designation. The AQA confirmed excellent baseline air quality across Rushcliffe Borough, with the HIMOINSA HFW-85 T5 generator's sub-50-hour annual operating profile producing negligible pollutant contribution. The FRA established that Sequential and Exception Tests were not applicable — the installation constitutes ancillary plant to an existing building, with no impact on floodplain storage or flood risk elsewhere. Both assessments confirmed no material planning constraints.

We prepared a Flood Risk Assessment for the erection of four panel courts and associated infrastructure at Dobbies Garden Centre, Peterborough. Although the site sits within Flood Zone 1 with low fluvial risk, Environment Agency surface water mapping identified areas of high pluvial flood risk across the site. Clay-rich soils with impeded drainage ruled out infiltration-based drainage, so we specified geocellular attenuation with Hydro-brake vortex flow control to restrict discharge to greenfield runoff rates for the 1-in-100-year plus 40% climate change event. Flood resilience measures were incorporated into the building specification throughout. The assessment demonstrated full compliance with NPPF requirements and Peterborough's local planning policies.

We prepared a Flood Risk Assessment for a residential rear extension incorporating basement accommodation in Sevenoaks, Kent. Despite the Flood Zone 1 classification and low surface water risk, the Sevenoaks SFRA (2024) identified the site within a mapped groundwater emergence area — underlain by permeable Folkestone Formation sandstone with high hydraulic connectivity to the water table. Groundwater flood risk was classified as high, driving a comprehensive mitigation specification: structural waterproofing to BS 8102:2009 using Type A, B, and C protection methods, internal perimeter drainage with automated sump pump and battery backup, construction-phase groundwater monitoring, and flood-resilient internal finishes throughout. The assessment gave Sevenoaks District Council the technical evidence needed to support planning approval.

We prepared a Phase 1 Contamination Risk Assessment for the conversion at 39 Consort Road, Peckham — a site immediately adjacent to a dense historic railway corridor, with nine contamination linkages assessed and a High UXO rating requiring further investigation.

We prepared an integrated Flood Risk Assessment and SuDS Strategy for a rear extension with basement accommodation on a high pluvial flood risk site in High Wycombe, on behalf of Archplan Design Ltd. The site's underlying New Pit Chalk Formation made infiltration-based drainage viable despite a medium groundwater classification. A combination of 175m² of permeable block paving and two 3m³ soakaways, designed using HR Wallingford StopUP hydraulic modelling, achieved zero discharge to the combined sewer across all modelled events — including the 1-in-100-year storm with 40% climate change allowance — representing a 100% reduction in peak runoff compared to existing conditions. Basement groundwater mitigation was specified to BS 8102:2009, incorporating Type A, B, and C protection methods with a sump pump and high-level alarm system.

We prepared a Flood Risk Assessment for a new community building at a recreation ground in Kings Langley, Hertfordshire — a Flood Zone 2 site adjacent to the Grand Union Canal, developed on behalf of Aitchison Raffety. The assessment identified medium fluvial risk, high groundwater risk from the underlying Lewes Nodular Chalk Formation with a water table at approximately 1.5m depth, and medium sewer flooding risk supported by 16 recorded incidents in the local postcode since 2015. Mitigation measures included waterproof concrete for below-ground structures and positive pump devices to prevent sewer backflow, alongside flood-resilient construction materials throughout. The FRA demonstrated full NPPF compliance and confirmed that the development could proceed safely without increasing flood risk to surrounding areas.

We prepared a Flood Risk Assessment for a partial demolition and residential extension at Vignobles, Old Mill Lane, Bray — a Flood Zone 3 site adjacent to the River Thames in the Royal Borough of Windsor and Maidenhead, on behalf of Studio AG Architects. The site carried high fluvial risk from the Thames, high groundwater risk from the permeable Shepperton Gravel Member aquifer with susceptibility exceeding 75% per the Windsor and Maidenhead SFRA, and medium reservoir breach risk. All habitable rooms were positioned on the first floor with finished floor levels a minimum of 600mm above the 1-in-100-year plus 20% climate change flood level. Ground floor construction was specified in flood-resilient materials including solid concrete floors, sealed service entries, and reinforced double-glazed frames for high-energy flow resistance. Floodplain storage volume was preserved throughout, confirming no increase in flood risk to neighbouring properties.

We prepared a Flood Risk Assessment for a proposed ancillary garden building at 19 Cole Park Road, Twickenham — a Flood Zone 2 site near the River Crane in the London Borough of Richmond upon Thames, on behalf of Gillum and Partners. Despite existing flood defences providing protection to the 1-in-100-year event, EA climate change mapping placed the site within the design flood extent for the 1-in-100-year plus 35% and 70% scenarios — a finding that directly informed the resilience specification. Finished floor levels were set 300mm above the 1-in-100-year plus 35% climate change flood level, with flood-resilient ground floor construction, sealed service entries, and geocellular attenuation with Hydro-brake flow control for surface water management. Medium surface water and reservoir breach risks were also assessed and addressed.

This project was a different kind of flood risk challenge — not a new building pushing into the floodplain, but a temporary glazed dining dome within the grounds of an established riverside hotel, needing a technically sound case to satisfy the LPA and Environment Agency.
We prepared the FRA for Bingham Hotel & Restaurant Limited for the proposed temporary dome at Bingham Riverhouse Hotel, 61-63 Petersham Road, Richmond upon Thames, TW10 6UT — a Flood Zone 3 site on the tidal Thames in the London Borough of Richmond upon Thames. Fluvial and tidal flood risk was high, reservoir breach risk was high based on EA wet-day breach mapping, and groundwater risk was medium, with the Richmond SFRA (2021) placing the site in the 50–75% susceptibility band. Surface water and sewer flooding risk were both low.
The assessment demonstrated that the dome's lightweight construction gives it negligible volumetric impact — it displaces no floodwater, obstructs no flow paths, and has no mechanism by which it could increase flood risk on or off site. As a minor householder application it was exempt from the Sequential and Exception Tests under NPPF footnote 62. Planning support confirmed on that basis.

We were appointed by Arkidraft Ltd to prepare the FRA for a proposed ground and first floor residential extension at 172 Abingdon Road, Oxford, OX1 4RA — a Flood Zone 3 site in New Hinksey with no formal flood defence protection. Unlike many comparable projects, this site carried high risk across four distinct flood sources: fluvial, groundwater, sewer, and reservoir breach.

Mitigation focused on raising all habitable rooms to first floor level with FFLs at least 300mm above the 1% AEP plus 20% climate change flood level, specifying flood-resilient ground floor construction throughout, and incorporating backflow prevention on all sewer connections. Planning support confirmed for Oxford City Council on that basis.

We prepared a Flood Risk Assessment for a prior approval change of use from office to residential at 40 Mill Place, Kingston upon Thames, KT1 2RJ — a Flood Zone 3 site in the Royal Borough of Kingston upon Thames, within the Hogsmill River catchment. The application was exempt from the Sequential and Exception Tests under NPPF note 62 as a change of use prior approval, but the flood risk case required robust technical justification. Environment Agency Product 4 data from the Hogsmill 2015 hydraulic model confirmed a 1-in-100-year plus 35% climate change flood level of 9.79m AOD, against an existing floor level of just 9.87m AOD. The proposed development raises the internal finished floor level to 10.09m AOD, providing 300mm of freeboard above the design flood level and delivering a meaningfully more resilient building than currently exists. Groundwater susceptibility is low per the Kingston SFRA (2021), surface water and sewer flood risk are low, and reservoir breach risk is medium. Resilient ground floor finishes, sealed service entries, and reinforced glazed frames were specified throughout. The existing Flood Response Plan, in place since 2008, provides established emergency evacuation procedures for occupants.

The site at 2a Guildford Road, Chertsey, KT16 9BJ sits in one of Runnymede's more complex flood risk environments — partially within Flood Zone 3, with historic fluvial incidents documented across the wider area and high surface water flood risk identified at the rear of the site. We prepared the FRA for Arkidraft Ltd in support of a prior approval application to convert an existing office building to residential studio flats, with the application exempt from Sequential and Exception Testing under NPPF note 62. The dual risk profile — high fluvial and high surface water — drove a two-strand resilience strategy: finished floor levels set at a minimum of 300mm above the 1-in-100-year plus climate change design flood level (to be confirmed against EA Product 4 data), alongside geocellular surface water attenuation with flow control, sealed thresholds, and moisture-resistant internal construction throughout. Groundwater risk is low, with the Runnymede SFRA (2018) indicating susceptibility only below ground level and the proposals including no basement elements. Sewer and reservoir breach risks are both low. The development does not increase the existing footprint, confirming no reduction in floodplain storage and no increase in flood risk on or off-site.

2 Guildford Road, Chertsey lies partially within Flood Zone 3 and is affected by both fluvial and surface water flood risk. We prepared a Flood Risk Assessment for Arkidraft Ltd in support of a prior approval application to convert an existing office building into residential studio flats. The site is exempt from Sequential and Exception Testing under NPPF note 62.

The mitigation strategy combined elevated finished floor levels set at least 300mm above the 1 in 100 year plus climate change flood level, with geocellular surface water attenuation, sealed thresholds and resilient internal construction. Groundwater susceptibility is limited to below-ground structures, and no basement is proposed. Sewer and reservoir breach risks are low. As the development retains the existing footprint, floodplain storage is unaffected and no off-site flood risk increase is anticipated.

This project was a ground floor rear infill extension at 5 Bishop Ken Road, Harrow, HA3 7HU — a Flood Zone 1 site in the London Borough of Harrow, where the primary flood risk consideration was surface water rather than fluvial flooding. The site is underlain throughout by London Clay Formation, a low-permeability bedrock that rules out infiltration-based drainage, and EA flood mapping identified a modelled surface water flood depth of approximately 0.2m on site, giving an overall medium surface water risk classification. All other flood sources — fluvial, groundwater, sewer, and reservoir breach — were assessed as low risk, with no historic flood events recorded at the address. The surface water strategy specified geocellular attenuation with flow control, profiled external ground levels to intercept overland flows, sealed door thresholds, raised air bricks, and moisture-resistant internal construction throughout. Sequential and Exception Tests were not required given the Flood Zone 1 designation. The assessment confirmed no increase in flood risk to the surrounding area.

We prepared a Basement Impact Assessment for the conversion of a detached dwelling into five flats at 39 Consort Road, Peckham — lowering and extending the existing basement, underpinning perimeter walls, and addressing the implications of working adjacent to a Network Rail retaining wall.

We prepared a Flood Risk Assessment for a residential extension in Flood Zone 3a at 121 Arthur Road, Windsor — a high fluvial risk site requiring a comprehensive resilience specification to satisfy the LPA and demonstrate no increase in flood risk on or off-site.

We prepared a Phase 1 Preliminary Risk Assessment for the change of use at 2 Guildford Road, Chertsey — a site within a Source Protection Zone, with a historic gasworks complex less than 100 metres to the southeast and former railway sidings on the boundary.

We prepared a Flood Risk Assessment for a Flood Zone 1 residential development at 196 Exeter Road, Harrow, where EA surface water mapping identified high pluvial flood risk despite the low fluvial classification — requiring a targeted drainage and resilience approach.

We prepared an Air Quality Mitigation and Ventilation Statement to discharge a planning condition for three retained flats at 20 Harmer Street, Gravesend — a listed building requiring careful integration of mechanical ventilation with the historic fabric.

We prepared a combined Flood Risk Assessment and SuDS Strategy for the conversion of a former conservative club in Burton Latimer — a Flood Zone 1 site where high surface water risk and medium groundwater susceptibility required a targeted drainage and resilience approach.

We prepared a Phase 1 PRA for 2a Guildford Road, Chertsey — a more complex contamination profile than its neighbour, with the site overlying a Principal superficial aquifer in SPZ Zone 2 and multiple off-site contamination sources within close proximity.

We prepared a Flood Risk Assessment for an office-to-residential conversion at 155-157 Muntz Street, Birmingham — a Flood Zone 1 site with low flood risk across all sources, where the focus was on delivering a compliant SuDS strategy to ensure no increase in surface water runoff.

We prepared a Flood Risk Assessment for a ground and first floor extension at 172 Abingdon Road, Oxford — a Flood Zone 3b functional floodplain site with high risk from four sources, requiring compensatory floodplain storage via a stilted 430mm void to replace the 13.62m³ of displaced floodwater.

We provided a combined flood risk assessment and SuDS strategy for a lower ground floor extension at 4 Riverdale Road, Twickenham — a Flood Zone 2 site near the Thames with high groundwater risk, achieving 50% betterment in peak discharge.

We prepared a site-specific Flood Risk Assessment for a householder extension at Dial House, Riverside, Twickenham — a Flood Zone 3a property fronting directly onto the tidal Thames in Richmond upon Thames, on behalf of Annie Shephard. Fluvial and tidal flooding is the governing source and was assessed as high, risk from artificial sources medium, and surface water, groundwater and sewer risks all low. A minor householder extension is exempt from the Sequential and Exception Tests under note 62 of the National Planning Practice Guidance, so the assessment turned on freeboard, resilience and evacuation. Finished floor levels are set above the modelled 1-in-100-year plus climate change level, the construction is specified as flood resilient throughout, and safe refuge is provided at first floor with Floodline registration. The FRA confirmed the extension does not reduce floodplain storage or impede conveyance.

We prepared a combined Flood Risk Assessment and SuDS Strategy for the demolition and replacement of a dwelling at 2B Vicarage Drive, East Sheen — a Flood Zone 1 site that the Richmond Surface Water Flood Risk mapping (2021) nonetheless places in a high-risk band, on behalf of Richard Simm. Surface water is the governing source and was assessed as high; groundwater was rated medium, which limits reliance on infiltration as the sole disposal route; fluvial, sewer and artificial-source risks are low. The drainage strategy reduces impermeable area from approximately 290m² to 200m² and layers four SuDS components: 11m² of extensive green roof, 450 litres of rainwater harvesting, 115m² of permeable paving and a 4.1m³ soakaway. The network is designed to the 1-in-100-year event with a 40% climate change allowance, delivering a measurable reduction in peak discharge.

We prepared a screening-level Air Quality Assessment and a Ventilation Strategy for 186 Dalling Road, London W6 0EU, to discharge Condition 9 of planning permission 2025/02481/FUL, on behalf of Athena Young of John Rich Architects. The site sits inside the borough-wide Hammersmith & Fulham Air Quality Management Area, yet measured and modelled concentrations fall well below the national objectives: indicative monitoring at Brackenbury Primary School, 159 metres north, recorded an annual mean nitrogen dioxide concentration of 28.2 µg/m³ in 2024 against the 40 µg/m³ objective, and London Atmospheric Emissions Inventory concentrations interpolated to the 2027 opening year indicate 19.6 µg/m³ at the site. That evidence supported a proportionate ventilation specification rather than a defensive one, with every intake and extract termination fixed on the approved drawings.

We prepared an air quality screening assessment and an Air Quality Mitigation and Ventilation Strategy for the conversion of the lower ground floor of Jurisdicial House, 2 Shepherd's Bush Road, London W6 7PJ, from a language school to a one-bedroom flat, on behalf of Jeremy Li. The report discharges Condition 6 of planning permission 2025/00356/FUL, granted on 10 September 2025, and had to be tested not only against the national objectives but against the tighter targets in the borough's Air Quality Action Plan 2025-2030: 10 µg/m³ for NO2, 15 µg/m³ for PM10 and 5 µg/m³ for PM2.5. The scheme introduces one car-free dwelling and falls below every EPUK/IAQM (2017) indicative screening criterion, so no dispersion modelling was undertaken. Mechanical ventilation with heat recovery was specified, with every termination fixed on marked-up drawings and designed around two restaurant extracts on adjoining premises.

We prepared a site-specific Flood Risk Assessment for a dormer roof extension at 78 Comeragh Road, London W14 9HR — a Flood Zone 3 site in Hammersmith & Fulham, on behalf of Cameron Jones Planning Ltd. The site carries an unusual combination of three high ratings: fluvial risk is high, reflecting residual risk in a defence overtopping or breach scenario on the tidal Thames; groundwater risk is high on the local hydrogeology and recorded water levels; and sewer flooding risk is high on recorded incidents in the surrounding postcode sector on the Victorian combined network. Artificial-source risk is medium and surface water risk is low. As More Vulnerable development in Flood Zone 3 the proposal engaged the Exception Test, which it passed: the extension places nothing new at ground level, removes no floodplain storage, and enlarges the safe refuge available above the design flood level.

We prepared a combined Flood Risk Assessment and Sustainable Drainage Strategy for 107 Downs Road, Hackney, E5 8DA, discharging conditions 3 and 4 of planning permission 2023/1273, on behalf of Arkidraft Ltd, alongside a Phase 1 Preliminary Risk Assessment for land contamination. The site is in Flood Zone 1 but surface water is the governing source: Environment Agency mapping places 54.6% of the site (255m²) within the 1-in-30-year extent and 83.6% (391m²) within the 1-in-1000-year extent, with modelled depths of 150-300mm across most of the site in the 1-in-100-year plus climate change event and an overland flow route crossing it from north-west to south-east. The existing site is wholly impermeable with no attenuation at all, so the strategy reduces impermeable area by 87.06m² (18.6%) and introduces 45.51m² of permeable paving over a lined 450mm sub-base.

We prepared a Basement Impact Assessment for a detached single-storey garden outbuilding with a basement level at 121 Lowdell Close, Yiewsley, UB7 8BA — a Flood Zone 1 site over a highly vulnerable Principal aquifer, on behalf of Adam Pisar. Each floor has a gross internal area of approximately 33m², with the basement formation level assumed at approximately 3.0m below existing ground level. The superficial deposits are the Lynch Hill Gravel Member over the London Clay Formation, with Worked and Made Ground recorded on and adjacent to the site. Two BGS boreholes 250-325m to the south recorded no groundwater to 2.0m and to approximately 6.0m, indicating that groundwater lies below the formation level. Groundwater flood risk is very low, the site is outside any Source Protection Zone, and the assessment delivered the screening and scoping outcome required by Hillingdon Local Plan Policy DMHD 3.

We prepared a site-specific Flood Risk Assessment for a single storey rear extension at 1 Partridge Mead, Maidenhead — a Flood Zone 2 site in the Royal Borough of Windsor and Maidenhead, on behalf of Phil Hurdwell of PJH Design. The assessment identified medium fluvial risk, the site falling within the 1-in-1000-year extent but outside the 1-in-100-year extent, and high groundwater risk arising from the permeable Thames valley gravels beneath the plot and their hydraulic connection to the river; surface water, sewer and artificial-source risks were all low. Mitigation set finished floor levels to provide freeboard above the design flood level, specified waterproof concrete with sealants at construction joints to all below-ground structures, and moisture-resistant materials throughout the ground floor. Planning permission was granted on 6 August 2026 under reference 26/01427/FULL.

We prepared a standalone site-specific Groundwater Flood Risk Assessment for a ground floor extension at 7 Purssell Close, Maidenhead — a Flood Zone 1 site on the Chalk where groundwater was the source in question and a single FRA chapter would not have carried the argument. The assessment built a four-strand evidence base: water levels held by the British Geological Survey for eleven Chalk boreholes and wells measured since 1977 within 2.1km of the site, the Environment Agency monitoring record, the borough Strategic Flood Risk Assessment and our own groundwater model. Every Chalk measurement falls between 23.24 and 26.17 mAOD against a site ground level of 32.69 mAOD, placing the water table some 7.3 to 8.2m below ground. Applying the largest median-to-peak range observed in the region — 3.2m over 49 years at Shottesbrooke Park — still leaves an extreme high-stand approximately 4.6m below ground level, and the rating is Low on evidence rather than on mapping.

We prepared a site-specific Flood Risk Assessment for a front porch, part single and part two storey side and rear extension, hip-to-gable roof alteration and rear dormer at 26 Lawn Close, Datchet, on behalf of Jagdeep Singh. The Flood Zone 2 site carries three elevated ratings: medium fluvial risk, high groundwater risk from the permeable Thames valley gravels and their connection to the river, and high artificial-source risk from the reservoir breach inundation extent; surface water and sewer risks are low. Rather than three parallel mitigation packages, the design answers all three with two decisions — all bedroom accommodation at first floor with finished floor levels at least 300mm above the 1-in-100-year plus 35% climate change flood level, and waterproof concrete with sealants to all below-ground structures. The application was validated on 30 July 2026 under reference 26/01517/FULL.

We prepared a combined Flood Risk Assessment and SuDS Strategy for the replacement of an existing dwelling at Poplars, Southlea Road, Datchet — a Flood Zone 3b site in the functional floodplain of the non-tidal Thames, on behalf of Sukhdeep Singh. Fluvial, groundwater, sewer and artificial-source risks are all high; surface water risk is low. The design places all bedrooms at first floor with finished floor levels well above the minimum 300mm freeboard over the 1-in-100-year plus 35% climate change level, lays the building out so that floodwater passes through rather than around it, and constructs the ground floor in solid concrete with resilient finishes so it can be inundated and returned to use. Impermeable area increases from approximately 470m² to 670m², offset by attenuation and source control designed to the 1-in-100-year event with a 40% climate change allowance, and floodplain storage is increased relative to the existing building.

We prepared a site-specific Flood Risk Assessment for a part two-storey side extension at Elm Farm, Boveney Road, Dorney, Buckinghamshire — a Flood Zone 2 site on the north bank of the Thames between Eton and Maidenhead, on behalf of Gareth Cotter of Gareth Cotter Architecture. The extension provides a garden room with a bedroom and ensuite over, together with a reorganised kitchen, dining and utility arrangement, and we worked from drawings 2609-GA-001A and 2609-GA-110 of July 2026. Fluvial, groundwater and artificial-source risks are each medium; tidal, surface water and sewer risks are low. Mitigation sets finished floor levels with freeboard above the modelled design flood level, specifies waterproof concrete with sealed construction joints to below-ground elements, and raises electrical services clear of it. The extension does not reduce floodplain storage or impede conveyance, and the modest increase in impermeable area is accommodated without increasing peak discharge.

We prepared a Flood Risk Assessment, SuDS Strategy and Flood Risk Sequential Test for the change of use and rebuild of 3 Grange Road, Egham — a Flood Zone 2 site in Runnymede — on behalf of Fiona Jones of Cameron Jones Planning Ltd. The scheme rebuilds on the same footprint and subdivides a dwellinghouse with ground floor offices into two self-contained flats: Flat 1 at 56.6m² GIA and Flat 2, a maisonette of 17.6m² at ground floor and 81.0m² at first floor. Fluvial risk is medium and sewer risk medium, while groundwater and artificial-source risks are both high, reflecting the Thames valley gravels and the reservoir breach inundation extent. The rebuild cuts impermeable area from approximately 276.6m² to 158.1m², a reduction of around 43%, and the drainage network is designed to the 1-in-100-year event with a 40% climate change allowance. The application is registered under reference RU.26/0845.

We prepared a Flood Risk Assessment with floodplain compensation design for a two-storey remodelling and extension at 92 Thames Side, Staines-upon-Thames — a Flood Zone 3b site in the functional floodplain of the non-tidal River Thames, on behalf of Kathleen Hoy. The extension adds approximately 21.5m² of ground floor footprint on the rear elevation, is More Vulnerable development, and sits where groundwater risk is rated High. The design flood level — the 1% annual probability event including climate change — is 14.91m AOD, and built conventionally the extension would remove 17.8m³ of floodplain storage below it. We set out two compensation routes: a piled floodable void with demolition of the existing conservatory, giving a net gain of approximately 17.8m³; or excavated compensation of 132m² at a mean depth of 0.16m providing 20.8m³, a net gain of approximately 2.7m³. Finished floor level is raised to 15.21m AOD.

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.

We prepared a site-specific Flood Risk Assessment and Flood Warning and Evacuation Plan for the conversion of a dwellinghouse (C3) to a children's home (C2) at 2 Sitwell Grove, Stanmore, Harrow, HA7 3NB, on behalf of Guardian Roots. The London Borough of Harrow declared application PL/2135/26 invalid on 14 August 2026 because the site falls within a climate change flood zone, and on 18 August 2026 its Infrastructure Team, as Lead Local Flood Authority, confirmed a medium surface water categorisation and directed that the submission comprise flood data and emergency planning information only. The site is in Flood Zone 1, but the climate change 1% AEP surface water extent covers most of it, so surface water governs. Both uses are More Vulnerable, so vulnerability does not increase, and the evacuation plan answers the changed occupancy profile. The submission resolved the validation objection.

We prepared a Flood Risk Assessment and SuDS Strategy for single storey rear and side extensions, a first floor extension and a detached garden room at 100 Whitchurch Gardens, Edgware, HA8 6PB — a Flood Zone 1 site in the London Borough of Harrow where surface water risk is high — on behalf of Alexander Awramenko of AS Made Studio. Tidal, fluvial, groundwater, sewer and artificial-source risks are all low; the high surface water rating follows from the low-permeability London Clay, on which rainfall that is not intercepted becomes runoff almost immediately. The proposals increase impermeable area from approximately 176m² to 302m². The strategy answers that 126m² increase with 179m² of permeable paving over a 300mm sub-base at 25% porosity taking the whole roof catchment, a silt trap upstream of the sewer connection, and 180m² of retained soft landscape.

We prepared a site-specific Flood Risk Assessment for a lower ground floor study extension with a glazed link, rooflights and landscaping at 38 The Dene, Sevenoaks, Kent, TN13 1PB — a Flood Zone 1 site — on behalf of James R Brown & Company Ltd. The assessment worked through all six flood sources and found tidal, fluvial, surface water, groundwater, sewer and artificial-source risk all low, with no historic flood events recorded at the address. Groundwater matters most, because the extension creates habitable accommodation below existing ground level and a low rating is what makes that arrangement straightforward. Mitigation was limited accordingly to threshold levels and external ground profiling to shed water away from the building, with no waterproofing, pumped drainage or raised floor level required. Sevenoaks District Council granted permission on 29 May 2026 under 26/00417/HOUSE.

We prepared a SuDS Strategy for a single storey rear extension to a dental surgery, with entrance alterations and the conversion of a garage to a cycle and bin store, at The Coach House, Victoria Road, Lydney, Gloucestershire, GL15 5DG — a Flood Zone 1 site with no watercourse within 20m — on behalf of Punit Shivhare. The commission followed the Flood Risk Management Officer's requirements, Gloucestershire County Council as Lead Local Flood Authority seeking compliance with the discharge hierarchy. The scheme reduces impermeable area from approximately 330m² to 200m², a reduction of 39%, and adds 180m² of permeable paving over a 300mm drainage layer at 25% porosity, providing 13.5m³ of sub-surface attenuation storage for the 1-in-100-year event with a 40% climate change allowance. Forest of Dean District Council granted permission on 18 August 2026 under P1568/25/FUL.

We prepared a site-specific Flood Risk Assessment for the change of use of the first floor of a commercial building at 48-50 Rolleston Street, Leicester, LE5 3ST, to Use Class E(d) as a gym — a Flood Zone 2 site in the River Soar and Willow Brook catchment — on behalf of Michelle Hill of Simple Planning Solutions. Fluvial risk is medium, consistent with the Flood Zone 2 designation, surface water risk is high, sewer risk is medium on a combined network, and groundwater and artificial-source risk are low. The proposal involves no external alterations, no new floorspace and no below-ground works, and E(d) is Less Vulnerable development, appropriate in Flood Zone 2 without the Exception Test. The assessment demonstrated an acceptable level of flood risk by virtue of elevation above the modelled flood levels, without reliance on additional mitigation.

We prepared a Flood Warning and Evacuation Plan for the conversion of part of the Former Methodist Church, Chapel Street, Skinningrove, TS13 4BH, into two two-bedroom houses, on behalf of Warsett Ltd, discharging condition 4 of permission R/2024/0379/CA granted on 9 January 2025. The site is at risk from Skinningrove Beck and is covered by the Environment Agency Flood Warning System, where the frequency and speed of response is 15 minutes — a steep coastal beck draining a small upland catchment onto a village at sea level, with a documented history of rapid flooding. The plan sets out the warnings available and their lead time, how it is triggered and by whom, and the actions required at each warning code. On a 15-minute response it directs occupants to safe refuge above the modelled flood level rather than to evacuation by road.

We prepared a combined Flood Risk Assessment and SuDS Strategy for the conversion of a detached dwelling into five flats at 39 Consort Road, Peckham — achieving 50% surface water betterment through a green roof, rainwater harvesting and permeable paving despite high pluvial and reservoir breach risk.

We prepared a combined Flood Risk Assessment and SuDS Strategy for a residential extension at 96 Popes Grove, Twickenham — a Flood Zone 1 site in the Thames corridor at Richmond upon Thames, on behalf of Kevin Eley. Fluvial, surface water, sewer and artificial-source risks were all low, but groundwater was rated medium on the Thames floodplain deposits beneath the site, which removed full infiltration as a reliable disposal route. The scheme reduces impermeable area from approximately 300m² to 270m² and adds two SuDS features: a 280 litre water butt for source control and 30m² of permeable paving over a 300mm drainage layer at 25% porosity, giving 2.25m³ of sub-surface attenuation. The network is designed to the 1-in-100-year event with a 40% climate change allowance, and the assessment confirmed that the extension does not increase flood risk to surrounding properties.

We prepared a SuDS Strategy for the change of use of Chippenham Pit Stop to a formalised lorry park — a Flood Zone 1 site near M4 Junction 17 where infiltration into the underlying Cornbrash Limestone delivered an 85% betterment on peak surface water runoff.