Noise Study
In order to predict operational noise levels, the internationally recognised noise modelling software, SoundPLAN, will be utilised.
- Within Task 1 Preliminary Noise Study to determine the likely noise distribution in and around the project locations and identifying likely noise restricted areas and compliance with project noise limits based on preliminary noise specification data
- Within Task 2 Detailed Noise Study, as per the Noise Allocation Study but the model shall be based on finalised noise specification data
The propagation methodology adopted within the SoundPLAN model is the International Organisation for Standardisation (ISO) 9613 ‘Acoustics – Attenuation of Sound During Propagation Outdoors’ (ISO, 1996).
ISO 9613 specifies an engineering method for calculating the attenuation of sound during propagation outdoors in order to predict the levels of environmental noise at a distance from a variety of sources. The method predicts the equivalent continuous A-weighted sound pressure level (LAeq) under meteorological conditions favourable to propagation from sources of known sound emission. The model takes into account the following physical effects:
- Geometrical divergence
- Atmospheric absorption
- Ground effect
- Reflection from surfaces
- Screening by obstacles
Preliminary Noise Study
In general terms, the objective of the preliminary noise study is to define whether the project is feasible from an acoustics point of view, and to identify any related impacts or ‘risks’ with regards to acoustic design. In addition, where it is considered that noise levels will not meet noise limits, the study will be used to allocate sound power levels to specific items of plant, set equipment noise limits and anticipate noise abatement measures.
The noise model will be developed using a combination of design sound power level data and industry standard sound pressure level data and baseline measured data (if available) for all noisy items of equipment. Subsequent noise contours will be superimposed onto a digital plot plan of the proposed facility along with existing background measurements.
The resultant cumulative noise contours from the proposed plant will be calculated within the facility and the surrounding environment. Areas of expected high noise exposure, or expected breaches in project noise limits that will subsequently require noise reduction techniques to be applied, will be highlighted.
Where required, and in liaison with engineers, technical and feasible mitigation measures will be incorporated into the model for both external and internal environs in order to achieve the required project noise limits. Where it is not technically feasible to reduce noise levels any further these areas will be delineated as noise restricted areas.
A log of all the noise data will accompany the report, which will include equipment tag number, plant name, power rating, sound pressure and sound power levels, and details of modelling parameters.
The modelling study will establish the degree of compliance of the provided design with the project noise limits and the expected requirement for any restricted areas. A Preliminary Noise Study Report with contour maps will be submitted (electronically) 3 weeks after receipt of all necessary data.
Detailed Noise Study
When specific vendor information is available then a detailed noise model will be assimilated based on specific machinery data supplied by individual vendors and the model re-run to determine exposure levels.
If required further mitigation measures will be discussed and integrated into the model. Where it is technically or economically not feasible to reduce noise levels any further these areas will be marked as hearing protection zones where specific PPE is to be worn.
Noise Study
In order to predict operational noise levels, the internationally recognised noise modelling software, SoundPLAN, will be utilised.
- Within Task 1 Preliminary Noise Study to determine the likely noise distribution in and around the project locations and identifying likely noise restricted areas and compliance with project noise limits based on preliminary noise specification data
- Within Task 2 Detailed Noise Study, as per the Noise Allocation Study but the model shall be based on finalised noise specification data
The propagation methodology adopted within the SoundPLAN model is the International Organisation for Standardisation (ISO) 9613 ‘Acoustics – Attenuation of Sound During Propagation Outdoors’ (ISO, 1996).
ISO 9613 specifies an engineering method for calculating the attenuation of sound during propagation outdoors in order to predict the levels of environmental noise at a distance from a variety of sources. The method predicts the equivalent continuous A-weighted sound pressure level (LAeq) under meteorological conditions favourable to propagation from sources of known sound emission. The model takes into account the following physical effects:
- Geometrical divergence
- Atmospheric absorption
- Ground effect
- Reflection from surfaces
- Screening by obstacles
Preliminary Noise Study
In general terms, the objective of the preliminary noise study is to define whether the project is feasible from an acoustics point of view, and to identify any related impacts or ‘risks’ with regards to acoustic design. In addition, where it is considered that noise levels will not meet noise limits, the study will be used to allocate sound power levels to specific items of plant, set equipment noise limits and anticipate noise abatement measures.
The noise model will be developed using a combination of design sound power level data and industry standard sound pressure level data and baseline measured data (if available) for all noisy items of equipment. Subsequent noise contours will be superimposed onto a digital plot plan of the proposed facility along with existing background measurements.
The resultant cumulative noise contours from the proposed plant will be calculated within the facility and the surrounding environment. Areas of expected high noise exposure, or expected breaches in project noise limits that will subsequently require noise reduction techniques to be applied, will be highlighted.
Where required, and in liaison with engineers, technical and feasible mitigation measures will be incorporated into the model for both external and internal environs in order to achieve the required project noise limits. Where it is not technically feasible to reduce noise levels any further these areas will be delineated as noise restricted areas.
A log of all the noise data will accompany the report, which will include equipment tag number, plant name, power rating, sound pressure and sound power levels, and details of modelling parameters.
The modelling study will establish the degree of compliance of the provided design with the project noise limits and the expected requirement for any restricted areas. A Preliminary Noise Study Report with contour maps will be submitted (electronically) 3 weeks after receipt of all necessary data.
Detailed Noise Study
When specific vendor information is available then a detailed noise model will be assimilated based on specific machinery data supplied by individual vendors and the model re-run to determine exposure levels.
If required further mitigation measures will be discussed and integrated into the model. Where it is technically or economically not feasible to reduce noise levels any further these areas will be marked as hearing protection zones where specific PPE is to be worn.