Page 231 - Alderney Regional Environmental Assessment of Renewable Energy: Environmental Report

Alderney Regional Environmental Assessment of Renewable Energy:
Environmental Report
devices in Alderney’s territorial waters (see Section 2.2.2) is considered to result in a higher
exposure to collision risk during operation and potentially moderate to major adverse impact.
Individual site specific assessments for renewable energy arrays should consider positioning
with respect to vessel traffic, routes and available depths. These aspects will be fully
considered within a Navigation Risk Assessment (NRA) following industry best practice, such
as the MCA’s MGN 371. Areas which are not suitably deep to allow vessels to navigate safely,
should become safety zones and identified as such on nautical charts with clearance distances
clearly marked. The effectiveness of these controls relies on both commercial and recreational
vessels maintaining up to date charting information. When considering the positioning of
marine renewable energy devices and substation platforms in the study area with respect to
commercial shipping and recreational navigation, it is particularly important to take into account
the following:
ƒ It is a requirement under the United Nations Convention on the Law of the Sea
(UNCLOS) that recognised sea lanes essential to international navigation are not
impeded;
ƒ Approaches to ports and harbours must be maintained; and
ƒ Approaches to marinas, anchorages and bay moorings must be maintained.
7.3.2.2 Changes to commercial shipping movement
The survey, construction, operation and decommissioning of tidal stream turbines, cable
routing, offshore substations, onshore substations and onshore wind turbine has the potential
to result in changes to commercial shipping movement. Commercial shipping movements are
intrinsically linked to changes in economic and social patterns and therefore sensitivity is
considered moderate throughout this assessment. Currently, commercial shipping through
Bailiwick waters (see Figure 27) is predominately HSC routes, passenger vessels and cargo
vessels. A mix of other commercial and military vessels also uses the sea area on an ad hoc
basis. Renewable energy developments will have implications for vessel movements such as
through route alterations or through a need to bring in construction plant, equipment and
renewable energy installations. These present both an increase in commercial vessel
movements and potential for associated craft including survey, maintenance and HSC.
Survey activities are likely to generate very minor increases in overall vessel movements at a
Bailiwick water scale and exposure to change is considered negligible to low resulting in an
insignificant/minor adverse impact. In terms of the construction and decommissioning
phases for all developments commercial vessel traffic will increase at the development site and
along the cable corridor. The construction and development of onshore facilities, such as the
onshore substation(s) and any wind farm developments will also generate additional
commercial vessel movements to transport heavy plant and equipment. Quantification of this
increase in marine traffic is not possible at this stage, and will depend on the chosen forms of
renewable technology, the installation requirements and associated cabling route(s). However,
given that nearly all equipment and plant will require transportation to Alderney, the exposure to
change during the onshore construction and decommissioning is assessed to be medium to
low Construction craft will be serviced by smaller vessels plying stores, equipment and
personnel from nearby bases of operation. This is likely to increase HSC and small cargo
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