6.2. Supplementary Information
- At the request of stakeholders, additional modelling was undertaken to determine the maximum injury ranges based on constant conversion factors at the maximum hammer energy of 4,000kJ for the SPLpk metric only. These are presented in Table 6.15. Modelled values at which instantaneous injury in the form of PTS could occur based on SPLpk thresholds were highest for the 10% conversion factor at the maximum hammer energy of 4,000 kJ. However, these were considered over precautionary for this metric as an animal is likely to flee the area starting from the first strike of the hammer and throughout soft start as the hammer energy ramps up. In addition, as described, a conversion factor of 10% is considered unlikely at the maximum hammer energy as the pile would be embedded and therefore the proportion of energy converted to sound would be reduced (thus the use of a reducing conversion factor).
Table 6.15: Summary of Injury Ranges due to the Maximum Peak Pressure over the Piling Sequence for Marine Mammals due to Impact Piling for Wind Turbine Foundations (“Maximum” Scenario) and OSP/Offshore Convertor Station Platform Foundations Using Range of Conversion Factors
Hearing Group | Threshold (Unweighted Peak) | Range (m) | ||||
|---|---|---|---|---|---|---|
1% Constant | 4% Constant | 10% Constant | 4% - 0.5% Reducing | 10% - 1% Reducing | ||
LF | PTS - 219 dB re 1 µPa (pk) | 109 | 223 | 359 | 83 | 134 |
HF | PTS - 230 dB re 1 µPa (pk) | 43 | 89 | 143 | 33 | 53 |
VHF | PTS - 202 dB re 1 µPa (pk) | 449 | 928 | 1,519 | 346 | 554 |
PCW | PTS - 218 dB re 1 µPa (pk) | 118 | 243 | 390 | 91 | 146 |
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[1] It is worth noting that the ranges reduce to zero in Figure 4.5 Open ▸ which is why the figure looks “empty”.