Environmental noise predictions using a statistical approach

Abstract

Noise pollution from industrial premises has the potential to have an impact on neighbouring properties. In New South Wales the Environment Protection Authority has developed the Noise Policy for Industry (NPfI). The NPfI requires noise assessments to be conducted using a typical assessment procedure that results in setting project noise trigger levels (PNTLs) which are the benchmark levels against which potential noise impacts from industrial developments are judged. The PNTLs are then used in Environmental Protection Licences to regulate the premises. The NPfI requires noise assessments to consider worst-case (i.e., noise-enhancing) meteorological conditions. In addition, regulators and consent authorities often require noise assessments to include a range of other conservative assumptions such as worst-case source levels and locations. This process appears to be very conservative, particularly considering that the PNTL in each assessment period (day, evening and night) are based on lowest 10th percentile background noise levels. This paper, through a statistical approach of using random probability distributions, will identify the likelihood that modelled noise levels and associated impacts are likely to occur and comment on the appropriateness of the conservative assessment process.