If construction is done badly, marinas and jetties have the potential to impact on the ecology of the estuary through poor working practices during the construction phase (noise and pollution), through loss of habitat or by indirectly causing changes to the way in which the estuary functions.
In order to avoid these impacts, waterfront development should comply with the following measures to reduce the associated impacts.
Potential disturbance to sediments during construction and subsequent redistribution of contaminated sediments within the estuary.
Potential changes to morphology of the estuary through interruption of coastal processes.
Stopping sediment disturbance during construction is unavoidable, but you can attempt to reduce impacts by:
• designing new structures so as to minimise effects on coastal processes, for example open piling rather than solid infill.
• ensuring the structure has minimal interference with coastal processes such as sediment movement to reduce longer term disturbance to sediment.
• using a low maintenance material such as stainless steel or timbers to construct piling to reduce operational impacts of the development.
• sourcing materials from a sustainable facility where possible and reflect as near to a natural structure as possible.
Loss of seabed habitat within footprint of slipways, jetties or other structures.
If the development involves land-take, create compensatory habitat elsewhere in the estuary, for example by managed realignment.
Temporary disturbance to birds during construction, if the development is situated close to important bird feeding areas.
Increase in general levels of bird disturbance within the estuary from increase in levels of boating.
• Locate the development away from important bird feeding areas if possible.
• If the development is situated near bird feeding areas, undertaking construction work outside the bird over-wintering period will minimise this impact.
Risk of pollution incidents during construction.
Risk of water quality impacts during operation from input of antifouling or boat-cleaning chemicals, etc.
• During construction seek out and follow Environment Agency guidance.
• Encourage best practice by the provision of waste receptor facilities, etc.
If the jetty or pontoon extends out into the main migratory route for salmonids then hammering piles can present an acoustic barrier. This can lead to potential changes to morphology of the estuary through interruption of coastal processes. During construction potential disturbance to fish passage during piling or blasting works.
• Design new structures so as to minimise effects on coastal processes, such as open piling rather than solid infill.
• Undertake any works, such as piling which could affect migration of fish outside Salmon and Allis shad migration season (March to October).
