View - North East Lincolnshire Council

BOC Immingham Dissolved Acetylene Project Environmental Statement: Vol. 2 Main Text
� vehicles (lorries and vans) loading unloading lime handling tankers; and
� general vehicle movements on site.
11.85 There is currently insufficient design details and corresponding noise data available with regard to
items of proposed plant equipment and therefore it is considered prudent to adopt a reverse
assessment approach whereby appropriate noise limits are set at the nearest residential property
and resulting noise levels are determined for the site taking into account noise attenuation due to
distance separation. Buildings should then be constructed and noise mitigation implemented (if
necessary) to ensure that the applicable noise limits are achieved.
Operational Noise Limits (Poplar Farm)
11.86 Poplar Farm is the nearest residential property to the development site (see Figure 11.1) and
therefore this property has been used to set appropriate operational noise limits targets taking into
consideration the guidance contained within BS 4142 and the recommendations of NELC’s EHO.
11.87 Facilities and premises that are closer to the development site than Poplar Farm are not
considered to be noise sensitive and are therefore not considered further in this assessment.
11.88 The lowest background noise level (LA90,T) measured near to Poplar Farm (position 1) was 44 dB.
Furthermore, the lowest background noise level measured at the continuous monitoring position
(position A) was also 44 dB (LA90,T). It is considered prudent to use this background noise level to
set the appropriate noise criterion since this will help ensure that the noise impacts and potential
for noise disturbance are minimised.
11.89 The EHO has recommended that the rating noise level from all fixed plant and equipment
associated with the development does not exceed the existing background noise level at Poplar
Farm. In accordance with BS 4142, applying this criterion is therefore likely to result in a less than
marginal significance with regard to the likelihood of complaints.
11.90 On this basis, all plant and equipment should not exceed a cumulative rating noise level of 44 dB
(LAeq,T) at Poplar Farm for typical operation.
11.91 This noise limit would also be suitable for night time and weekend working (should this be
required) as the prevailing noise climate in the local area is typically similar for daytime, night time
and the weekend.
Noise Attenuation Due to Distance Separation
11.92 Using standard acoustic principles for determining the attenuation of sound over distance for a
point source, distance corrections in the order of 6 dB per doubling of distance from the source
have been used in our predictions.
11.93 Sound attenuation due to ground absorption and atmospheric absorption is deemed negligible
and this assessment is therefore considered to be a worst-case scenario. Furthermore,
attenuation due to screening (such as that provided by the new earth embankments or other
natural features) is also considered to be negligible in this assessment.
11.94 Assuming a direct line of sight and a separation distance of 550 m between source and receiver
results in noise attenuation in the region 55 dB (LAeq,T).
11.95 Again, this is a worst-case scenario since this separation distance is to the nearest site boundary,
as opposed to a specific plant activity location and therefore assumes that all plant and activities
will take place at the site boundary. In practice, plant and activities are of separated by a greater
distance than that used in the predictions and also various items of plant equipment will be
housed within buildings that will provide a greater degree of noise attenuation via the building
envelope construction.
5100935.404 Environmental Statement August 2011 202