Benbow Environmental prepared an air impact assessment for the development application for a mobile asphalt plant to be based in Nowra. The proposal included delivery and storage of raw materials and recycled asphalt on site, as well as the manufacturing process performed on a modified large mobile vehicle. Potential air emissions included dust emissions from truck movements on site as well as materials storage and handling, sulphur oxides and nitrogen oxides from the manufacturing process, and odour from manufactured asphalt product. This original assessment has recently been updated for the client’s application to increase annual production. Computer modelling of air pollutant dispersion was performed using conservative assumptions under a worst-case operating scenario, and it was found that over 24 hours the particulates concentration experienced at nearby sensitive receptors exceeded the NSW EPA based assessment criteria. The client is already using several control measures including semi-enclosed bins for materials storage and a baghouse filter on the exhaust stack. The Benbow Environmental consultant examined the modelling further and identified the main source of dust emissions was from materials handling to and from stockpiles. Thus it was recommended that the client installed vertically-stacked water sprays and operated these during materials handling activities in order to prevent dust travelling off-site. Feedback has yet to be given.
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