Waterside Apartments, Nottingham

COMBINED CASE STUDIES: AIR QUALITY & FLOOD RISK ASSESSMENT
Short Case Study
Emergency Generator Installation: Environmental Assessment for High-Rise Residential Development
A comprehensive environmental assessment comprising Air Quality Assessment and Flood Risk Assessment was undertaken for the installation of an emergency diesel generator at a high-rise residential development in West Bridgford, Nottingham. The generator provides statutory backup power supply for firefighting lifts in accordance with Building Regulations requirements for buildings exceeding 18 metres in height.
Air Quality Assessment
The air quality assessment evaluated baseline conditions using local authority monitoring data and Defra background concentration maps. Results demonstrated excellent existing air quality, with nitrogen dioxide concentrations consistently below the annual mean objective of 40 µg/m³ throughout 2021-2024. All Air Quality Management Areas within Rushcliffe Borough have been revoked, confirming sustained compliance with national objectives.
The HIMOINSA HFW-85 T5 generator specification meets 97/68/EC emissions standards, representing best available technology. Given the emergency-only operational profile (typically less than 50 hours annually), the generator will have negligible impact on local air quality. Substantial headroom between existing pollutant concentrations and Air Quality Objectives provides considerable capacity for minor, intermittent emissions without risk of exceedance.
Flood Risk Assessment
The flood risk assessment addressed the site's location within Environment Agency Flood Zone 3, indicating high probability of fluvial flooding from the adjacent River Trent, alongside elevated risks from surface water, groundwater, and potential reservoir breach scenarios.
The assessment evaluated all potential flood sources in accordance with National Planning Policy Framework requirements. The site benefits from flood defences providing protection up to the 1 in 100-year event. The installation represents a minor alteration to existing development, with no extension to the developed area, no alteration to site levels or drainage characteristics, and no material impact on flood risk. The negligible volume of the generator unit will not reduce floodplain storage or increase flood risk elsewhere.
Conclusions
Both assessments concluded that environmental considerations do not present material constraints to planning permission. The installation:

Satisfies statutory Building Regulations requirements for emergency power provision
Employs best available emissions technology with negligible air quality impact
Incorporates appropriate flood resilience within existing development footprint
Aligns with national and local environmental policies
Demonstrates no increase in flood risk elsewhere

The project exemplifies how statutory infrastructure requirements can be satisfied in environmentally sensitive urban locations through appropriate technology selection, comprehensive assessment, and policy-compliant design.

Long Case Study
Integrated Environmental Assessment for Emergency Infrastructure in Constrained Urban Environment: Addressing Air Quality and Multi-Source Flood Risk
Project Overview
This integrated environmental assessment addressed air quality and flood risk considerations for the installation of emergency generator infrastructure at a high-rise residential development in West Bridgford, Nottingham. The project presented dual environmental challenges: demonstrating air quality compliance in an urban setting adjacent to a former Air Quality Management Area, whilst addressing complex flood risk arising from the site's Flood Zone 3 location beside the River Trent.
The assessment required careful interpretation of national planning policy to determine appropriate assessment scope for ancillary plant equipment serving existing development, balancing statutory Building Regulations requirements against environmental protection objectives.
Regulatory Context
Buildings exceeding 18 metres in height require secondary power supply for firefighting lifts under Approved Document B (Fire Safety), BS EN 81-72, and BS 9991. This statutory requirement necessitated emergency generator installation, triggering environmental assessment under the National Planning Policy Framework.
The site's location presented specific regulatory considerations:

Air Quality: Proximity to Nottingham City Council's Air Quality Management Area, despite lying within Rushcliffe Borough where all AQMAs have been revoked
Flood Risk: Flood Zone 3 location requiring flood risk assessment, with consideration of Sequential Test and Exception Test applicability
Integrated Assessment: Need to demonstrate that both environmental constraints could be satisfied simultaneously through appropriate design and mitigation


AIR QUALITY ASSESSMENT
Baseline Air Quality Review
A comprehensive baseline review incorporated multiple data sources to characterise existing air quality conditions:
Local Authority Monitoring: Rushcliffe Borough Council operates an extensive network of nitrogen dioxide diffusion tubes and automatic monitoring stations. The nearest monitoring locations recorded:

Diffusion tube data: 19.6-26.2 µg/m³ annual mean NO₂ (2024)
Automatic monitoring at Trent Buildings (70m from site): 24.5 µg/m³ (2024)
Zero exceedances of the 1-hour mean objective (200 µg/m³)
Declining trend: 29.3 µg/m³ (2021) to 23.2 µg/m³ (2024)

AQMA Status: All Air Quality Management Areas within Rushcliffe Borough were revoked during 2017-2025, confirming sustained achievement of objectives across the local authority area.
Background Concentrations: Defra predicted background concentrations for 2025:

NO₂: 13.1 µg/m³
PM₁₀: 13.0 µg/m³
PM₂.₅: 7.5 µg/m³

All values substantially below relevant Air Quality Objectives, indicating no significant pollution sources affecting baseline conditions.
Assessment Methodology
The assessment followed EPUK & IAQM guidance "Land-Use Planning & Development Control: Planning for Air Quality" (January 2017). This established framework provides a two-stage screening process:
Stage 1: Determines when air quality assessment is necessary based on development scale and nature
Stage 2: Establishes criteria for detailed air quality modelling
The guidance explicitly recognises that standby emergency generators operating for limited periods (typically less than 50 hours per year) do not require detailed assessment, as infrequent operation will not result in significant impacts on annual mean pollutant concentrations.
Generator Specification
The HIMOINSA HFW-85 T5 generator represents best available technology for emergency standby applications:

Emissions Compliance: Stage IIIA standards under Directive 97/68/EC (amended by 2002/88/EC and 2004/26/EC)
Engine Technology: FPT IVECO NEF45SM3 with common rail direct injection, turbocharging, and aftercooling
Operational Profile: Monthly testing (1 hour) plus six-monthly load testing, totalling <50 hours annually
Acoustic Design: Soundproofed enclosure with residential-grade silencer (-35 dB(A))

Impact Assessment
Quantitative consideration confirmed negligible air quality impact:

Substantial Headroom: Existing NO₂ concentrations (23.2-26.2 µg/m³) are 34-41% below the Air Quality Objective (40 µg/m³)
Minimal Annual Operation: <50 hours annually represents <0.6% of the annual period
Modern Emissions Control: Stage IIIA technology ensures minimal pollutant release during operation
Effective Dispersion: External exhaust discharge facilitates rapid dispersion in urban environment

Air Quality Conclusions
The assessment concluded that air quality considerations do not constrain planning permission:

Existing air quality is excellent with sustained objective compliance
Generator specification employs best available emissions technology
Emergency-only operation ensures negligible pollutant contribution
Substantial headroom exists between baseline and objectives
Full compliance with national and local air quality policies achieved


FLOOD RISK ASSESSMENT
Site Characteristics and Baseline Conditions
Topography: LiDAR data indicates relatively flat ground at approximately 9-10m AOD, consistent with surrounding urban landscape.
Geology: British Geological Survey mapping identifies Chester Formation sandstone bedrock overlain by Holocene alluvium (clay, silt, sand, gravel) characteristic of the River Trent floodplain.
Soils: Loamy and clayey floodplain soils with naturally high groundwater, reflecting the site's floodplain location.
Flood Risk from All Sources
Fluvial Flooding (HIGH RISK)
Environment Agency Flood Map for Planning identifies the site within Flood Zone 3, indicating >1% annual probability of flooding. Key considerations:

Immediate adjacency to River Trent (10,000 km² catchment)
Flood defences provide protection to 1 in 100-year event
Climate change mapping indicates site within future design flood extent
Historical flooding: Multiple events recorded (1947, 1960, 2000, 2007)

Surface Water Flooding (MEDIUM RISK)
Environment Agency surface water mapping indicates medium risk:

Localised high risk in wider area (roads, footways)
Site benefits from road gullies and established drainage infrastructure
No direct surface water flow paths across development
Existing drainage provides substantial protection under design storms

Groundwater Flooding (HIGH RISK)
Rushcliffe Borough Preliminary Flood Risk Assessment (2023) indicates ≥50% susceptibility:

Shallow groundwater tables characteristic of floodplain
Permeable superficial deposits facilitate rapid groundwater movement
Hydraulic connectivity to River Trent
No historical records of groundwater flooding at site

Reservoir Breach (HIGH RISK - LOW PROBABILITY)
Environment Agency mapping shows site within potential inundation extent under both "dry-day" and "wet-day" failure scenarios. Extremely low probability due to stringent reservoir regulation under Reservoirs Act 1975.
Tidal Flooding (NEGLIGIBLE RISK)
Site located well inland, approximately 40km upstream of tidal limit at Cromwell Weir.
Development Proposals and Policy Interpretation
The assessment required careful consideration of NPPF Sequential Test and Exception Test applicability:
Nature of Development:

Ancillary plant equipment serving existing building
Required by statutory Building Regulations
Located within existing building footprint (car park)
No extension to developed area or change of use
Negligible volume (~5.3 m³) with no impact on floodplain storage

Not Essential Infrastructure: The generator does not constitute "essential infrastructure" as defined by NPPF. It is not operational infrastructure that must be located in a flood risk area; location determined by practical considerations (proximity to substation, access, acoustics).
Minor Alteration to Existing Development: The installation involves:

No new floor space or accommodation
No change to vulnerability classification (remains "More Vulnerable" residential)
No alteration to site levels, drainage, or flood risk characteristics
No reduction in floodplain storage capacity
No increase in flood risk elsewhere

Sequential Test and Exception Test Applicability
The assessment concluded that Sequential and Exception Tests are not required because:

The installation comprises emergency plant required by Building Regulations, not discretionary development
It represents minor alteration to existing development, not introduction of new vulnerable uses
No change to site vulnerability classification occurs
The negligible volume has no material impact on floodplain function
The installation cannot reasonably be located outside the flood risk area as it must serve the existing building

This interpretation aligns with NPPF intent to apply sequential risk-based approach to location of new development, rather than to ancillary works serving existing buildings.
Flood Risk Management
Despite Sequential/Exception Tests not being required, the assessment identified flood risk management measures:
Flood Resilient Design:

Generator positioned at existing ground level (9-10m AOD)
Weatherproof soundproofed enclosure protects against water ingress
Integral fuel tank eliminates vulnerable external tankage
Electrical connections comply with BS 7671 with appropriate IP ratings

Emergency Operation Profile:

Operates on standby basis only (<50 hours annually)
Activates only if mains power fails during emergency
Low probability of concurrent flood and fire events
Building evacuation procedures take precedence during flooding

No Increase in Risk Elsewhere:

Negligible volume (5.3 m³) has no measurable impact on floodplain storage
No alteration to drainage arrangements or runoff rates
No impedance to overland flow paths
No impact on flood defence infrastructure integrity

Flood Risk Conclusions
The assessment concluded that flood risk considerations do not constrain planning permission:

Comprehensive multi-source flood risk characterisation completed
Installation comprises ancillary plant for existing building
Sequential/Exception Tests not applicable to this development type
No increase in flood risk elsewhere demonstrated
Appropriate flood resilience incorporated in design
Full NPPF compliance achieved


INTEGRATED CONCLUSIONS
Environmental Acceptability
The integrated environmental assessment demonstrated that both air quality and flood risk can be satisfactorily addressed through appropriate generator specification, location, and operational controls. Key findings:
Air Quality:

Existing conditions excellent with sustained objective compliance
Best available emissions technology specified
Negligible impact from emergency-only operation
Substantial headroom below Air Quality Objectives

Flood Risk:

Comprehensive multi-source risk assessment completed
Installation within existing developed footprint
No increase in flood risk elsewhere
Appropriate flood resilience incorporated

Policy Compliance
The installation aligns with environmental policies at all levels:
National Planning Policy Framework:

Paragraph 187(e): No contribution to unacceptable air pollution levels
Paragraph 199: Sustains compliance with air quality objectives
Paragraph 167: Does not increase flood risk elsewhere
Paragraph 173: Appropriate assessment of flood risk undertaken

Rushcliffe Local Plan:

Policy 41 (Air Quality): Emissions minimised through technology selection
Policy 2 (Climate Change): Flood resilience incorporated
Policy 17 (Managing Flood Risk): No increase in flood risk elsewhere

Statutory Requirements:

Satisfies Building Regulations requirements for high-rise buildings
Emissions comply with 97/68/EC standards
Installation does not compromise environmental objectives

Technical Innovation and Best Practice
This integrated assessment demonstrates several best practice principles:
Proportionate Assessment: Risk-based approach recognising distinction between major new development and minor ancillary works, avoiding unnecessary complexity where impacts are demonstrably negligible.
Integrated Evaluation: Simultaneous consideration of multiple environmental constraints, ensuring synergies are identified and conflicts resolved through appropriate design.
Policy Interpretation: Clear analysis of Sequential Test applicability, recognising that not all planning applications constitute "development" in the sense intended by NPPF sequential approach.
Technology Selection: Specification of best available emissions technology appropriate to emergency standby application, balancing statutory requirements with environmental protection.
Multi-Source Risk Assessment: Comprehensive consideration of all potential flood pathways (fluvial, pluvial, groundwater, reservoir breach) rather than focusing exclusively on mapped flood zones.
No Increase in Risk Elsewhere: Explicit demonstration that the fundamental NPPF requirement not to increase flood risk elsewhere is satisfied through detailed analysis of floodplain storage, drainage impacts, and flow conveyance.
Project Outcomes
The integrated environmental assessment successfully demonstrated that:

Statutory Building Regulations requirements can be satisfied in environmentally constrained locations
Best available technology minimises air quality impacts to negligible levels
Appropriate flood risk management can be achieved for ancillary infrastructure
Comprehensive assessment provides robust evidence for policy compliance
Environmental protection objectives and building safety requirements are compatible

The project exemplifies how emergency infrastructure can be delivered in sensitive urban environments through appropriate technology selection, comprehensive environmental evaluation, and clear policy interpretation. The assessment provides a robust evidence base supporting planning permission whilst ensuring environmental protection objectives are maintained.
Professional Commentary
This assessment represents best practice in environmental impact assessment for minor development in constrained urban locations. It demonstrates:

Regulatory Expertise: Clear understanding of when different policy tests apply and how to interpret guidance proportionately
Technical Competence: Integration of monitoring data, modelling outputs, and strategic assessment evidence
Practical Solutions: Balancing statutory requirements with environmental constraints through appropriate specification
Clear Communication: Presenting complex technical and policy arguments in accessible format for decision-makers

The integrated approach ensures that all environmental considerations are addressed comprehensively whilst avoiding unnecessary complexity where impacts are demonstrably negligible. This proportionate, evidence-based methodology provides a robust framework for assessing similar proposals in environmentally sensitive urban locations.