Page 236 - Alderney Regional Environmental Assessment of Renewable Energy: Environmental Report

Alderney Regional Environmental Assessment of Renewable Energy:
Environmental Report
7.3.2.9 Potential for equipment parts to become detached from devices
During the operation of tidal stream devices there is a risk that equipment parts from tidal
devices could become detached and become a navigation hazard to nearby navigation routes,
thereby creating a risk of collision. There is also a small risk that tethered devices could break
free of the moorings during extreme weather conditions and collide with other devices or
vessels. Given regular maintenance and the equipment parts mainly being heavy (and
therefore predominantly sinking), exposure to change is considered low to negligible and the
sensitivity low resulting in an insignificant/minor adverse impact.
7.3.2.10Lighting of the tidal works and structures causing confusion to passing vessels
During periods of construction and maintenance the lighting of works from construction,
installation and cable laying vessels, plus associated barge craft could be confusing to passing
vessels. This is a temporary effect during periods of reduced visibility (fog, heavy
rain/sleet/snow, haze, twilight and night time).
During construction and decommissioning of the tidal stream turbines, cable routeing and
offshore substations the presence of working lights can provide confusion to passing vessels.
All vessels engaged in renewable energy works will carry lights and shapes complying with the
requirements of COLREGS. The greater risk of confusion from lighting will be to smaller
recreational craft where crews may not have access to a range of navigational aids such as
those installed on commercial vessels. The risk of lighting induced confusion can be mitigated
through increased awareness from information in notice to mariners and passage planning by
craft to avoid construction areas where practical to do so; therefore the exposure to change is
considered low to negligible and the sensitivity low.
During the operation of tidal stream turbines and offshore substations, lighting on the structure
has the potential to cause confusion to passing vessels. However best practice measures can
be used to minimise any potential issues and therefore exposure change is considered
negligible to low and sensitivity to change low resulting in an insignificant/minor adverse
impact.
7.3.2.11Changes to risk management and emergency response
Search and rescue exercises and operations can take place throughout Bailiwick waters, both
within and adjacent to renewable development areas. The presence of tidal arrays and
offshore substations has the potential to affect risk management and emergency response
during the construction, decommission, cabling and the operational phases of development.
During construction and decommissioning of the tidal stream turbines, cable routeing and
offshore substations there is a risk of vessels straying into development safety zones for a
range of reasons, including a vessel not under command, or a vessel struggling to maintain its
course and speed in heavy weather. In this instance the ship’s crew and the emergency
services and their personal would be at risk in performing their duties to preserving life at sea;
therefore the exposure to change is considered negligible to medium and the sensitivity
moderate resulting in an insignificant to moderate adverse impact.
R/4001/7 212 R.2129