Specialist supermarket acoustic consultancy services provided to Aldi for new Stores – latest is in Chester

29 November 2016 by Rob Kirkaldy, Senior Consultant

As part of their ongoing expansion program in the North West, Aldi are seeking planning permission for a new 1,887m2 supermarket at the Inchcape Mercedes-Benz dealership site located off Parkgate Road in Chester. To form part of the planning application, Spectrum, acting as their supermarket acoustic and noise consultant, was required to prepare a noise impact assessment report, in order to satisfy the requirements of the Local Planning Authority.

We were appointed by Jones Lang LaSalle (JLL), on behalf of Aldi, to be the supermarket acoustic consultant on the project and produce a noise impact assessment report. The first job was to identify the key sources of noise at the proposed development:

• Mechanical services plant, including ventilation and cooling equipment
• HGV deliveries
• Customers and vehicles in the proposed car park

The proposed development site is located in close proximity to a number of existing dwellings. As the supermarket noise consultant on the project, we also needed to identify the key noise sensitive receptor locations to be referenced in the assessment.

To establish the existing background noise levels at the nearby receptors, we carried out attended noise measurements during the most sensitive daytime and night-time periods, when each of the identified sources of noise would have the highest impact.

The assessment of noise from both mechanical services plant and deliveries was carried out in accordance with BS 4142:2014 Methods for rating and assessing industrial and commercial sound. This requires the Specific Sound Levels from each of the sources to be determined at the identified residential receptor locations. To do this the noise modelling software package Predictor V11.1 was used; this follows the procedures outlined in ISO 9613-1:1993 Acoustics – Attenuation of sound during propagation outdoors. The noise model took account of the following in its calculations:

• Source sound power level (for point, line and area sources)
• Reflection from nearby structures and source directivity
• Distance from noise source (geometric spreading)
• Atmospheric absorption
• Acoustic screening of intervening structures and topography
• Ground absorption
• Ground effects (which includes the height of ground relative to the noise source)

The noise model outputs the results visually using noise contours shown on a map of the site and surrounding area. The results of the initial model were used to develop a range of mitigation measures to ensure acceptable levels of noise to residents and the community. For this project the measures proposed included a fully enclosed delivery bay, silencing for identified items of mechanical services plant and screening in the form of site boundary acoustic fences.

The assessment of noise from both mechanical services plant and deliveries was then carried out by comparing the predicted Rating Levels with the measured Background Levels for the most sensitive periods all in accordance with BS 4142:2014. The results were then presented in the noise impact assessment report. The levels from these sources were also compared with the guideline absolute noise levels listed in Guidelines for Community Noise – World Health Organization, 1999 (WHO) in the noise impact assessment report.

With the proposed mitigation measures in place, the levels of noise associated with each of the potential sources of noise at the proposed supermarket were shown to have a low adverse noise impact at each of the nearby residential receptor locations. Furthermore, the predicted noise levels were shown to be comfortably lower than the absolute noise levels set out in the WHO guidelines.

Being able to demonstrate to the local planning authority and other Stakeholders that a development such as this will not comprise residential and community amenity is vitally important in building trust between Aldi, their customers and the local community.

Further information on mixed and retail developments