Acceptable Noise Levels

MPG11 & PAN50

Prior to 1993, there were no nationwide guidelines for setting noise limits from minerals workings. Research commissioned by the Department of the Environment in 1986 identified a wide spread of approaches by local authorities to setting noise limits for minerals workings. The findings of this research ultimately led to the publication of MPG 11¹⁵⁵ in 1993 and PAN 50 Annex A¹⁵⁶ in 1996. These documents still provide the current guidance on acceptable noise levels in England, Wales and Scotland. The documents relate the acceptability of noise levels from minerals operations to the noise levels experienced at noise-sensitive properties, although it is accepted that for practical reasons, it may sometimes be necessary to set a noise limit at the site boundary or other location.

The guidance recognises the difference between the long term extraction operations carried out at mines and quarries, and the short term operations including baffle mound construction and removal. The limits for standard daytime operations fall into the range of 45-55dB L_{Aeq(1 hr)} . This basically means that the 'average' noise level measured over a one hour period must not exceed the noise limit that is set within the range of 45-55dB(A). Some MPAs aim to establish a noise limit at the noise sensitive property which is not more than 10 dB greater than the background level. In other words, where background noise levels, prior to the commencement of work, at the mine or quarry are below 45dB L_A90, a limit of below 55dB L_Aeq could be set.

Noise limits of up to 70dB L_{Aeq(1 hr)} are recommended for the short term activities of construction and removal of baffle mounds. It is suggested that these limits are applicable for up to eight weeks in a year. The documents also suggest a nominal night-time limit of 42dB L_{Aeq(1 hr)} for minerals operations.

In England, a draft of guidance to replace MPG 11¹⁵⁵ has already been produced for consultation. This document is currently referred to as MPS 2 Annex 2¹⁶¹. The guidelines for long term operations are similar to those in MPG 11¹⁵⁵, although the guidelines for short term operations are 3dB more stringent at 67dB L_{Aeq(1 hr)}. It also acknowledges that a level of below 55dB L_Aeq could "impose unreasonable restrictions on the mineral operation. In such cases the limit should be 55dB L_Aeq". This is obviously leaves room for discussion on what constitutes "unreasonable restrictions".

The guidance in Wales has recently been amended by Minerals Technical Advice Note (Wales) 1: Aggregates (March 2004)²⁵² and is outlined below.

MTAN (Wales) 1

This document supersedes paragraphs 31 to 42 of MPG 11¹⁵⁵, which are most of the paragraphs that relate to the setting of noise limits. MTAN1²⁵² states that noise limits should relate to the background noise levels, subject to a maximum daytime noise limit of 55 dB(A) where background noise levels exceed 45 dB(A). Where background noise is less than 45 dB(A), noise limits should be defined as background noise levels plus 10 dB(A).

Night-time working limits should not exceed 42 dB(A) at noise sensitive properties. Daytime working is defined as 0700-1900 hours and night-time as 1900-0700 hours.

During temporary and short-term operations higher levels may be reasonable but should not exceed 67dB(A) for periods of up to 8 weeks in a year at specified noise sensitive properties.