GovWire

You must carry out detailed modelling assessment on any emissions that you did not or could not screen out through yourair emissions risk assessment. Detailed modelling will identify if these emissions could harm the environment or human health.

You need to include all the information explained in this guide, in your report. If you do not include some information, youll need to explain why. There needs to be enough information in the report to make an exact copy of the model.

You need to demonstrate an understanding of the environmental implications of the emissions based on the best available science at the time of the submission, recognising any potential gaps in knowledge for new and developing technologies or processes. This includes an understanding of their environmental fate.

If your risk assessment identifies that your operation is likely to cause odour problems, you may need to model odour exposure. The guideH4 odour managementhas more information.

Explain your report

At the start of your report, you must:

• explain the purpose of the study
• describe the site
• explain the process by which your emissions occur, their duration and frequency
• explain the modelled emission scenarios and how they represent your operations

Include a location map

You must include a map that:

• shows the location of the proposed site, site boundary and surrounding land use
• shows the size of the modelled area
• uses National Grid referencing and indicates terrain contours, such as the Ordnance Survey Landranger series (1:50,000)

List emissions and environmental standards for air

You must provide a list of the chemical substances modelled.

You must identify the relevantair emission environmental standards forthese substances.

For substances for which no air emission environmental standard is listed, you must provide a unique identifier, for example, the CAS registry number if available, or the chemical specification.

You must also provide a unique identifier where:

• you have derived a new environmental assessment level (EAL) for a substance
• you have proposed an alternative EAL for a substance

Work out ambient and background levels

You must:

• work out a representative value for the background concentration
• explain how your background concentrations are representative of the local environment and assessment timeframe

Find this information from:

• local authority ambient monitoring data
• datafrom Department for Environment, Food and Rural Affairs (Defra) national monitoring networks
• local air quality management background mapsand modelled background pollution data produced by Defra

If you use different sources for this information, you need to explain why and explain why it is appropriate.

You should consider whether there are any other plans, projects or permissions that are not currently included in the background concentrations. You may need to model and provide the emissions parameters for other plans, projects or emissions, where relevant.

Explain the model

The model you use must be:

• fit for purpose
• based on established science
• validated
• independently reviewed

You must justify that the model you use is suitable to represent the transport, dispersion and transformation processes of the substances you emit.

You must list the:

• dispersion modelling software used
• software name, including version number
• type of model, for example Gaussian plume model
• supplier

Explain emission parameters

You must explain:

• how your modelled source terms represent your operational scenarios and emissions
• the source type and any assumptions or simplifications

You must list all the relevant parameters and their units in a table for point source emissions. You must explain any parameters not included or not relevant.

You must explain how you have worked out the emission rates used in your model. You need to demonstrate that the emissions are appropriate to the assessment purpose.

You can calculate emission rates using:

• emission concentrations from the relevantBAT conclusion document
• measured concentrations from your own monitoring
• benchmark concentration values from similar plant

Where you use measured or benchmark concentrations, you need to include the raw data and the source of the information.

You must also include any other relevant data to demonstrate the emissions used in your model are a valid representation of the operational scenario being modelled, including:

• temperature and pressure conditions
• actual oxygen and moisture levels
• emission rates or other source parameters that vary with time

If you have modelled emissions from source types other than point source emissions (for example, emissions from area, line or volume sources) you need to explain the source type and how it represents the emissions from your operations.

Explain the modelled domain and receptors

You need to justify the resolution of the model receptor grid you use.

If relevant to your model, you must give the assumed height above ground level for receptors.

You must also give details of any discrete receptor and include grid references used to assess the impact at sensitive locations.

You must consult any local development plans to include potential future sensitive receptors in your assessment.

Explain meteorological data and surface characteristics

You must explain your choice of meteorological data and say why its representative. You also need to explain how the surface characteristics you have chosen represent the land use within your model. For example, surface roughness, albedo, Bowen ratio or Priestley-Taylor parameter.

Your report must include:

• the location of the meteorological data in relation to the model domain
• the number of years covered by the data 5 is recommended, but it must be a minimum of 3
• the source of the data, for example, the UK Met Office
• whether the meteorological data is observed or from a numerical weather prediction (NWP) model with an appropriate resolution
• a description of the data quality and uncertainties relating to any alternative meteorological data
• any data processing or filling you have done to improve the data quality
• a wind rose showing the distribution of wind speed and direction

Explain terrain and building treatments

You must justify why you have included terrain and building treatments in your assessment. If you have not, youll need to explain why.

Your report should:

• explain the source, format and processing of digital terrain data used in the model


View the original news story