NOISE ATTENUATION BY GREEN BELTS

This paper outlines the results of noise attenuation investigations at eight planatation sites in Jharia (JCF) and Raniganj (RCF) coalfields in India. With a B&K Type 4224 noise source operated on spectrum I mode, the maximum total noise attenuation for Leq at 50 m depth of the green belt was found to be within 18·8–21·1 dB (A) in JCF and 18·7–21·0 dB (A) in RCF. Excess noise attenuation (Leq) exclusively due to green belts in JCF and RCF was 3·3–6·0 and 3·6–5·7 dB (A) respectively. Excess attenuation for higher frequencies (>250 Hz) was more [>4 dB (A)] than that for lower frequencies (⩽125 Hz). Average trend of total noise attenuation (in percentage) at different depths of the green belt was evaluated to compute the minimum desired thickness of green belt for different locations in coal mining complexes. Based on characterization of the plantation sites and measured noise attenuation, a multivariable linear relationship was established for excess noise attenuation.