We can provide modeling services for most substances in an atmospheric context. Please find the below services, we can help out with virtually any requirement you may have so please call for a no obligation discussion.

We can model releases from oil and gas pipe lines. We can model dispersion of dense gas plumes, or neutrally buoyant gas plumes. This kind of modeling and reporting is carried out when choosing sites of refineries, or tank farms. They can also be conducted when a sensitive receptor is introduced next to an existing source.

Since the beginning of 2020 Natural England (UK) have been asking for ammonia assessments for all kinds of planning applications. Ammonia Dispersion Modelling

Odour modeling is carried out for all kinds of processes and in some cases as a precaution when situating non-odourus developments next to odourus ones. For example, a sewage works might require an odour assessment (understandably) but a house next to a sewage works might also require one. Odour Modelling

When smells, dust or pollutants come out of a stack (tall chimney) they do not always go straight up. They often come back down gain some where nearby. But where? We can make a good estimate using atmospheric modeling.

Post "diesel gate" we are all aware that diesel, and to a lesser extent petrol cars cause air pollution. But how far do you have to be away from a road, before the affect is lessened? We can model the road in question and find a good spot for you to build you proposal, or to build you new road.

Air Dispersion Modeling for Industrial Emissions: Best Practices and Workflows

For the surface treatment and metal finishing industries, managing exhaust emissions requires careful engineering and regulatory compliance. Facilities handling substances like hexavalent chromium (Cr6) and cyanide operate under strict oversight worldwide. Environmental agencies, such as the US EPA and the UK Environment Agency (EA), require comprehensive air dispersion modeling to demonstrate that emissions meet safety thresholds prior to construction.

The standard tool for this process is AERMOD. Accurately translating factory geometry, chemical data, and local meteorology into a compliant model requires specific engineering and software workflows.

Stack Design: Height, Aerodynamics, and Safety

The physical design of an exhaust stack significantly impacts environmental permitting, particularly when dealing with heavily regulated substances where regulators apply the ALARP (As Low As Reasonably Practicable) principle.

Engineering the Height Buffer

Modeling a stack exactly to the minimum required height leaves no margin for operational variances, such as minor flow rate fluctuations or nearby construction. Standard practice involves modeling an engineering buffer (e.g., adding 1 to 2 meters) and running a Stack Height Sensitivity Analysis in AERMOD. This demonstrates to regulators that the chosen height provides a reliable and practical safety margin.

Managing Multiple Pollutants and Building Wake

Acidic Cr6 exhaust and alkaline cyanide exhaust must be kept entirely separate to prevent the formation of hydrogen cyanide (HCN) gas, necessitating distinct Local Exhaust Ventilation (LEV) systems. However, placing a short exhaust stack adjacent to a tall stack can cause aerodynamic building downwash, where the taller structure's wake forces the shorter plume downward.

The standard industrial solution is a Multi-Flue Stack. A single structural shell houses separate internal flues that terminate at the exact same elevation. This allows both plumes to bypass the building's aerodynamic wake and disperse effectively side-by-side.

The below section was written by a machine.

Technical Guidance: Atmospheric Dispersion Modelling and Air Quality

Atmospheric dispersion modelling is a sophisticated mathematical simulation used to predict how air pollutants disperse in the ambient atmosphere. This technical process is fundamental to modern environmental planning, allowing developers to quantify the ground-level concentration of emissions from a specific source before a project begins. Whether addressing flue gas from a stack or fugitive dust from a construction site, accurate modelling ensures that a project remains compliant with UK Air Quality Standards and local planning requirements.

Advanced Software Methodologies: AERMOD and SCAIL

The choice of modelling software is critical for ensuring technical authority during the planning process. We utilize industry-recognized platforms to provide defensible data for regulatory review.

AERMOD Dispersion Modeling: A steady-state plume model that incorporates air dispersion based on planetary boundary layer turbulence structure and scaling concepts. This is widely used for industrial air quality impact assessments.
SCAIL (Simple Calculation of Atmospheric Impact Limits): A specialized tool used primarily for assessing the impact of ammonia emissions from agricultural developments on sensitive habitats, ensuring compliance with RAMSAR and SSSI requirements.
Meteorological Data Integration: High-resolution weather data, including wind speed, direction, and atmospheric stability, is integrated into the model to simulate real-world conditions over a multi-year period.

Applications in Odour and Industrial Permitting

Atmospheric modelling is not limited to traditional pollutants; it is an essential tool for managing complex odour impact assessments. By calculating odour detection thresholds and frequency of exposure at sensitive receptors, we can design effective air abatement solutions. These results are often a mandatory requirement for environmental permitting applications and help to prevent nuisance complaints once a facility becomes operational.

Strategic Integration with Environmental Impact Assessments (EIA)

In the context of a full Environmental Impact Assessment (EIA), atmospheric modelling provides the evidence base for the air quality chapter. It allows for the comparison of different design scenarios and the verification of proposed mitigation measures, such as stack height increases or the implementation of a dust management plan. With over 15 years of industry experience and 900+ projects delivered across the UK, SWEL provides the professional oversight and technical insight needed to secure project consent. Our reports offer the professional accreditation (IES/IAQM) required to satisfy local authorities and environmental regulators, securing the future of your development.