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2.3
Step 3 - Sound Power Levels for Percussive Piling
The sound power level of each of the percussive piling units included in the CNP application shall be obtained from Table 2 having regard to the piling method and pile type combination. If any piling method and pile
type combination included in the CNP application does not appear
Table 2 the Authority may make use of such sound power level as it considers appropriate.
2.4 Step 4 Summation of Noise Levels
be
in
The sound power levels obtained in Step 3 shall
summed
logarithmically in accordance with Table 3 to obtain a total sound power
level.
2.5 Step 5 Distance Attenuation
The plan distance or, where appropriate, the slant distance between the
NSR and the pile location nearest to the NSR shall be determined.
The position of the pile location nearest to the NSR shall be selected
having regard to any pile layout drawing supplied by the CNP applicant. If no such drawing is supplied to the Authority the position shall be taken to be the position on the piling zone boundary nearest to the NSR.
The appropriate correction factor
correction factor for distance attenuation shall be
obtained from Table 4. This correction factor shall be subtracted from
the total sound power level obtained in Step 4 to give the Predicted Noise Level (PNL) at the NSR.
2.6 Step 6 Corrections for the Effect of Barriers
In cases where the Authority considers that all of the percussive piling works will be totally screened by a substantial barrier when viewed from
the NSR,
a negative correction of 10 dB(A) shall be applied to the PNL obtained in Step 5.
such as
Substantial barriers shall be taken to be large solid objects,
buildings ΟΣ topographical features, which will act as effective Barriers which are small, lightweight, incomplete or
temporary, such as site fences or hoardings, are not to be considered.
acoustic screens.
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