Azura-Edo Independent Power Plant Environmental Impact ... - IFC

8.2.2 Operation
With the implementation of the mitigation measures, the construction noise
during civil works such as site clearance, or the use of jackhammers, pile
drivers and the like, there is a potential of the noise exceeding more than 5 dB
above the IFC noise guideline limit (ie 60 dB during the day and 50 dB during
the night). If this occurs, this would result in major residual impacts for the
duration of these (unmitigated) works.
However, the likelihood of the noise levels reaching above these levels is low
and the duration of the impact would be very intermittent and would occur
only under specific circumstances. Taking this into account, the residual
impact is considered to remain negligible.
The most significant operational noise sources at the closest noise sensitive
properties (NSR 1, 2 and 3) are the walls and roofs of the Gas Turbine
Generator building. Mitigation will be focused on the highest noise sources
identified in Table 7.17 and therefore noise will be reduced from this source.
Noise from the generators within the buildings are likely to be significantly
greater than 85 dB(A) internally. As part of mitigation through design and to
reduce the noise levels, the walls and roofs have been modelled as emitting
facades with an equivalent sound pressure level of 85 dB(A) at 1 m from the
facades. The gas turbine generator building is well designed to ensure
breakout noise from the gas turbine is minimised. The following measures
form part of this design:
• Azura’s design ensures that reverberant sound from the gas turbine is
minimised internally, for instance by using an acoustic enclosure. A
Hushclad double-skin enclosure will be used with good door seals which
will be replaced regularly to meet the specifications for 82 dB at 1 m from
the source. If the 82 dBA for the enclosure is not feasible with these
measures, then the turbine building will be upgraded to heavier walls or
more internal absorption or a concrete block wall to achieve the same
result.
• Exhaust stacks will be designed to meet a power level of 92 dB(A).
• Azura’s design shall ensure that all walls, roof, windows and doors to the
building have a high noise reduction rating and ensure that there are no
significant gaps. Air conditioning/air flow requirements shall be
designed to take account of noise breakout.
Mitigation for Cumulative Impacts
• Azura Power will further refine the noise modeling of the plant to avoid >
45 dB at the four farms to the west of the plant by implementing design
measures such as attenuators on the stacks, cladding on the turbine
AZURA EDO IPP
8-4
DRAFT EIA REPORT