Stilted coastal development

Impact

Sediments can be disturbed from drilling into the seabed. Smothering can be an issue if there are important species in close proximity of the drilling work.

Stilted structures are likely to cause a lower level of sediment disturbance because of how they are constructed in comparison to solid structures.

Suggested measures to reduce impact(s)

Stopping sediment disturbance during construction is unavoidable, but you can attempt to reduce impacts by:

• ensure the structure has minimal interference with coastal processes such as sediment movement to reduce longer term disturbance to sediment.
• use a low maintenance material such as stainless steel or timbers to construct piling to reduce operational impacts of the development.
• source materials from a sustainable facility where possible and reflect as near to a natural structure as possible.

Impact

Sediments can be disturbed from creation of solid structures. If the sediments are contaminated it can be an issue to habitats and species in close proximity to the drilling.

Stilted structures are likely to cause a lower level of sediment disturbance due to the nature of how they are constructed in comparison to solid structures.

Suggested measures to reduce impact(s)

To reduce the risk of pollution incidents during construction phase, the developer is advised to seek and follow Environment Agency guidance.

Impact

The location of where the drilling occurs can have impacts on the estuarine hydrodynamics.

Suggested measures to reduce impact(s)

Ensure the structure has minimal interference with coastal processes, such as tidal flows.

Impact

Some direct loss will occur within the footprint of the structure, but stilted structures are likely to impact less than solid structures due to a minimal amount of the structure interfering in the environment.

Suggested measures to reduce impact(s)

• The size of the structure should be no longer than necessary in terms of protrusion into the estuary.
• If the development involves land-take, create compensatory habitat elsewhere in the estuary, for example by managed realignment.

Impact

Increased levels of noise during construction will disturb birds. If the works are located close to important winter and wildfowl feeding areas then works should be scheduled to avoid sensitive times of year.

Suggested measures to reduce impact(s)

• 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.

Impact

Water quality issues can arise if sediments are released due to drilling of foundations for the construction of solid structures. The amount of sediment disturbed is dependant on the scale of the development proposed and is likely to be less significant for stilted structures compared to solid structures due to less of the sediment needing to be disturbed during construction.

Suggested measures to reduce impact(s)

Use sustainable urban drainage schemes (SUDS) to minimise run-off and associated impacts.

Impact

Slipways, steps and boathouses will cause shading of the habitat beneath to varying levels, depending on the scale of the development, and species composition may change as a result. Therefore, applicants will need to describe existing habitat, identify the changes likely to occur and make a judgement in terms of the biodiversity gain/loss.

Construction of stilted developments has the potential to create less shading than solid structures and it can allow for a greater amount of light to penetrate through.

Suggested measures to reduce impact(s)

• Adopt more natural coastal protection measures where possible, such as beach nourishment.
• Use materials for construction with complex surfaces with crevices or indentations to encourage colonisation by marine flora and fauna.
• The design of walkways should allow for maximum of amount of light to penetrate to the rock or mud surfaces underneath to minimise loss of biological productivity.

Impact

Loss of fish nursery areas if the development involves land claim or disturbance to the foreshore.

Suggested measures to reduce impact(s)

Minimise working area during construction and only allow construction plant onto the shore if strictly necessary.

Impact

Potential impact on otters using the estuarine waters, within the water and the land surrounding the estuary.

Suggested measures to reduce impact(s)

Ensure that bridges and culverts are designed to accommodate the safe passage of otters and migratory fish.

Impact

Potential impact on bat roosts due to modification of waterfront properties and/or loss of tree roots.

Suggested measures to reduce impact(s)

Ensure planning application is screened for potential impact to bat roost. Developments should be informed by a Bat Roost Survey if necessary. Outlining a strategy of minimising unnecessary artificial lighting for proposed development.

Impact

Potential impact on lichen communities on river side trees, exposed substrate and mining heritage buildings in the Upper Tamar.

Suggested measures to reduce impact(s)

Developments with the potential to impact on river side trees, exposed substrate and mining heritage buildings on the Upper Tamar should be informed by a Lichen Survey.