Page 302 - Alderney Regional Environmental Assessment of Renewable Energy: Environmental Report

Alderney

Regional Environmental Assessment of Renewable Energy:

Environmental Report

Receptor

Potential Mitigation

Report

Section

Where appropriate to the local species ensuring that piling (if required)

commences using an agreed soft start procedure; the gradual increase of

piling power, incrementally over a set time period, until full operational

power is achieved. The soft-start duration should be a period of not less

than 20 minutes. The soft-start procedure will vary according to hammer and

pile design and other factors.

Marine

mammals and

turtles

Automatic shutdown of rotary mechanism by proximity sensor to avoid death

or injury by collision with tidal infrastructure;

Marine mammal monitoring undertaken for a defined period of time during

initial operation with potential turbine shutdown when a mammal is within

50m of turbine rotors;

Regular surveillance for carcasses and post mortem evaluation of carcass

stranding and assessment of cause of death;

Establishment of an active sonar system which detects marine mammals at

sufficient range from the turbine to allow a precautionary shutdown to occur

automatically; and

Iterative reviews of the Draft Plan taking account of information available

from other trial deployments elsewhere and monitoring data collected during

implementation of early developments under the Plan. Co-operation with

regulators in France and the Channel Islands should be pursued to ensure

that as much as possible can be learnt from early deployments of tidal

energy devices;

Restrict any piling to periods of low species activity within annual and diurnal

cycles as appropriate to avoid displacement of species by underwater noise

caused by infrastructure installation (piling);

Where appropriate to the local species, ensure that piling commences using

an agreed soft start procedure; the gradual increase of piling power,

incrementally over a set time period, until full operational power is achieved.

The soft-start duration should be a period of not less than 20 minutes. The

soft-start procedure will vary according to hammer and pile design and other

factors;

Ensuring that piling activities do not commence until half an hour has

elapsed during which marine mammals have not been detected in or around

the site. The detection should be undertaken both visually (by Marine

Mammal Observer) and acoustically using appropriate Passive Acoustic

Monitoring equipment. Both the observers and equipment must be deployed

at a reasonable time before piling is due to commence. This should include

ensuring that at times of poor visibility e.g. night-time, foggy conditions and

sea state greater than that associated with force 2 winds, enhanced

acoustic monitoring of the zone is carried out prior to commencement of

relevant construction activity; and

Produce a cable laying plan to minimise EMF at or above the seabed. This

will include consideration of cable design and installation (e.g. bury cables

where practicable).

5.5.2.11

Nature

conservation

Consider a zone of avoidance around designated sites (this will vary

depending on the sensitivity of qualifying interest features and the

spatiotemporal scale of pressures brought about by activities associated

with specific projects);

Minimisation of survey / construction / decommissioning works in designated

sites;

Consider alternative installation methods (including non-invasive measures

such as Horizontal Directional Drilling (HDD)) to avoid an adverse effect on

site integrity;

5.6.2.14

R/4001/7

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R.2129