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BOC Immingham Dissolved Acetylene Project Environmental Statement: Vol. 2 Main Text
11.68 The nearest dwelling to the site is Poplar Farm located on South Marsh Road approximately
550 m from the site boundary. Over these distances, noise levels would be reduced by 35 dBA to
42 dBA, depending on ground type and characteristics. Assuming all items of equipment could be
in operation during a typical assessment period (a working day) and be in use at least 50% of the
time, the resulting construction noise levels at Poplar Farm would be between 48 and 55 dB LAeq.
These levels would be commensurate with the ambient noise levels in the area, which were
measured as 50 to 55 dB LAeq.
11.69 Even if all items of plant equipment were in operation at the same time, the total noise levels
(ambient noise and construction noise combined) would, at worst, be no more than 5 dBA higher
than ambient noise levels. Considering the temporary nature of construction activities, this is
considered an acceptable level of impact when assessed in accordance with BS 5228 (example
method 2, E.3.3). Furthermore, it is highly unlikely that all items of plant would be in operation at
the same time and therefore this assessment represents a worst-case scenario. On this basis, the
actual impacts are likely to be less than those predicted. Overall, depending on the timing of
activities and the coincident use of plant equipment, the severity of the temporary impact of
construction noise on human receptors is considered to be Minor to Moderate.
Piling Noise
11.70 In addition to the above, a detailed piling noise assessment has been undertaken in order to
inform the ecology assessment and determine the likely impacts on local bird populations. This
assessment has been undertaken because the highest construction noise levels are anticipated to
be during any piling works and therefore piling activities have the greatest potential to disturb bird
populations. The potential impacts would depend on the type of piling method used, ground
conditions, and the power rating and size of the piling rigs.
11.71 The piling noise assessment has been undertaken in accordance with BS5228 guidelines and has
utilised NoiseMap 5 calculation software to produce noise contour maps for different piling types.
11.72 Piling has been assumed to have a source height of 5 m above ground level. The ground
conditions between source and receiver are assumed to be soft.
11.73 Four different piling types have been assessed with two different scenarios for each piling type.
The first scenario is for two piling rigs operating simultaneously in the main area of the site where
buildings are to be located and the other scenario is for a single piling rig operating near to the
proposed bridge.
11.74 The piling types assessed and the associated noise levels are shown in Table 11.8.
Table 11.8 Piling Type and Associated Noise Level
Equipment Piling Type BS 5228 Reference LAeq,T at 10 m (dB)
Rotary bored piling large rig Table C.3 14 83
Rotary bored piling mini rig Table C.3 17 76
Continuous flight auger piling Table C.3 21 79
Hydraulic hammer rig (5 tonne) Table C.3 1 89
11.75 The noise contour maps for the different piling types and anticipated piling locations are provided
in Appendix 11B. The noise contours represent noise levels at a receiver height of 0.1 m above
ground level to represent bird populations residing in the surrounding fields. The results of the
assessment and potential impact on birds are discussed in Chapter 10.
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