Our Projects

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.

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.

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.

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.

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.

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 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.

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 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 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 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 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 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 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 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.

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 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.

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 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 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 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 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 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 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.