The construction of an array of 48 wind turbines and one substation is being undertaken in the locale of Gunfleet Sands, off of the Essex coast in England. With the commencement of piling operations, complaints were received by Tendring District Council from the General public. Investigation into the noise alleged was undertaken in October 2008. With the potential for further complaints, Tendring District Council's Environmental Services in conjunction with DONG Energy carried out a more detailed longer term study and investigation into the impact of piling operations on residential areas in November and December 2008. Continuous monitoring at 3 sites adjacent to properties on the seafront was undertaken to establish the levels. The measurement locations were chosen to be representative of the existing noise climate to which the closest noise sensitive residences are exposed. Background monitoring between the piling operations showed that the noise levels followed a diurnal pattern due to the influence of wave action on the foreshore adjacent to the monitoring sites. The existing noise climate at Sites 1 and 3 is largely dominated by tidal noise with occasional local traffic at this time of year. Site 2 is more dominated by road traffic noise during the day, on a busy suburban approach road into Clacton on Sea. In the early hours, again, tidal noise dominates this noise climate. During piling operations the weather conditions and wind direction had a significant impact on the sound propagation over the water between the piling and the onshore SLM's. Weather conditions play a large part in onshore noise perception. Psychoacoustics may also play a part in people's perception of noise disturbance from these piling works. It is a new noise source and has considerable AM properties which are generally considered more noticeable. This shows a peak SPL of 53dBA, but more pertinently a maximum Amplitude Modulation (AM) of approx 17dB. That is, the difference between the highest and lowest readings giving a significant contrast in the noise climate. Atmospheric absorption, humidity, wind and temperature gradients, ground and water effects reflecting sound greater distances.inland than would be expected, as confirmed by complaints received from some miles inland. In the U.K. BS 5228, in conjunction with the Control of Pollution Act 1974, gives advice on noise and vibration control on construction sites. Part 4 refers to a code of practice for noise and vibration control applicable to piling operations. In essence it gives source data for different types of noise source and methods for calculating noise produced by these sources, using sound power levels or LAeq levels and standard attenuation over distance calculations. Given the large distances involved, and the high levels of impact noise at the Gunfleet Sands site it is open to discussion whether this is appropriate for these piling operations.
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