Controlling Noise’s Unexpected Impacts12 October 2021
Noise and vibration ‘interactive nuisance’ can swiftly become ‘annoying interference’. With crucial residential, industrial and infrastructure projects in the UK pipeline it is vital to protect the public from noise’s potentially complex multiple-effects.
Noise can be a strange phenomenon. The ‘deafening’ exhaust of, say, a nearby generator may form a local health and safety hazard. But the radiating effects of sound sources that seem relatively benign close up can pose a serious environmental risk to sensitive ‘receptors’ much further away.
Unwanted sound, or noise, is increasingly regarded as an unacceptable intrusion into daily life. This makes attenuating – or lessening – its effects a high priority for both site operators and human ‘receptors’. The case is made even stronger by evidence that long-term noise exposure above a certain threshold can have negative physical and mental health effects.
At the same time society urgently needs new community, housing, employment and economic developments. But these cannot be vulnerable to either obvious or ‘hidden’ noise impacts.
Theoretically, this could lead to conflict between commercial activity on one hand, and sustainable growth and environmental protection on the other.
In practice, delivery of ‘good neighbour’ technical solutions via accurate baseline surveys, professional data assessment, advanced modelling and comprehensive assessments can satisfy all parties.
Noise is a growing aspect of environmental concern in the planning process. Designing-out potential noise impacts at the outset is more effective than well-meaning mitigation attempts later.
An example that typically affects local people and communities across the UK are new and expanding quarries which can generated significant levels of noise.
Quarries can generate noise with two main impacts. The first is the hearing and general wellbeing of employees and visitors. This is generally treated as a health and safety issue.
However, the second crosses the line from being a purely H&S problem into an environmental aspect potentially affecting people, noise-sensitive areas and properties in a wide area around a quarry.
H&S impacts are legally covered by The Control of Noise at Work Regulations and include employer and employee responsibilities for acoustic risk assessment, eliminating or mitigating workplace noise, monitoring and specialist training.
However, when it comes to protecting people beyond the quarry boundary, the main deciding factor is the loudness of operations against guideline limits based on the prevailing background noise climate.
Quarrying noise assessment
Enzygo’s acoustic team recently carried out a noise baseline survey, analysis, assessment, and modelling project, with conclusions and mitigation recommendations, for a proposed extension to a sand and gravel extraction in Worcestershire.
The aim was to assess the noise emissions from extraction, restoration and exportation operations at the nearby noise-sensitive properties against the prevailing background noise levels measured at the properties during typical time periods when these operations would be taking place. The results of the assessment led to the determination on how potential impacts could be minimised, mitigated or removed at source.
As per Government guidance, the objective was to ensure that extraction operations at the quarry could be undertaken whilst maintaining a good standard of amenity at the local sensitive receptors by meeting the legislative limits of 10dB(A) above the prevailing background noise levels without putting unreasonable operational burdens on the site operator.
Noise monitoring equipment was positioned strategically to gather both background and ambient noise levels at locations representative of the nearest residential receptors; the existing quarry was working at the time but no operational noise were audible at the measurement locations.
Noise levels generated by operations within the proposed extension area were predicted to nearby sensitive receptors using the industry standard calculation methodology outlined in British Standard 5228:2009+A1:2014 ‘Code of practice for noise and vibration control on construction and open sites, Part 1: Noise’ using the proprietary noise modelling software CadnaA.
The resulting predicted noise levels were compared noise limits derived from the background noise levels in accordance with the Planning Practice Guidance for Noise, and more specifically paragraphs 019 to 022 of the Planning Practice Guidance for Minerals – https://www.gov.uk/guidance/minerals.
We also considered the three criteria set out in Noise Policy Statement for England (NPSE), namely: – No Observed Effect Level – NOEL; Lowest Observed Adverse Effect Level – LOAEL; and Significant Observed Adverse Effect Level – SOAEL. We aimed for LOAEL but were able to meet NOEL.
Enzygo’s noise expertise
Enzygo provides specialist consultancy advice relevant to noise and vibration assessments, providing technical support for property developers, architects, planners, land agents and industrial clients on residential, industrial, energy, waste and commercial development schemes.
Full details of our work on noise and vibration measurement and assessment, 3D noise modelling, and detailed acoustic design are available on https://www.enzygo.com/services/noise/.
The loudest noise heard by humans
Man-made noise impact is nothing compared to what nature can produce. At 10.02am local time on 27 August 1883, a volcanic explosion on the Indonesian island of Krakatoa was eventually heard 3,000 miles away in Mauritius as “the distant roar of heavy guns”.
That is the equivalent distance of Dublin to New York which sound travelling at 765 miles/1,233 km per hour covered in four hours; it is estimated the explosion was heard across one thirteenth of the world’s surface. The eruption itself reached speeds of more than 1,600mph – half a mile a second.
A barometer 100 miles away recorded the event as a pressure of more than 2.5 inches of mercury – which converted to 172dB over a huge area; a jet engine produces 150dB.
Noise is linked to minute air molecule vibrations. But there is an upper limit – circa 194mph in the Earth’s atmosphere – after which a shock wave is formed. This happened at Krakatoa. However, low level sound circled the planet once every 34 hours for nearly five days.
Krakatoa was probably exceeded by the air burst of a meteoroid above Tunguska in Siberia in 1908 with an estimated impact equivalent to 1,000-Mega-ton bomb and a decibel rating of 300-315dB.
Surprisingly loud noises are generated by nature. Blue whales, Earth’s largest animal, rumble at low frequencies at 140dB. But they are beaten by sperm whales “clicking” at 230dB. On land, New Zealand’s Kakapos flightless parrots call to each other at up to 132dB over distances of more than six kilometres!
If you have any questions about noise and vibration assessment, measurement, modelling or acoustic design, or feel more information would be useful, do please contact me directly.