Estuary Edges

Design Principles

The following 17 points, if followed, should result in a successful feature:

  1. Avoid encroaching into the estuary (see Figure 1).
  2. Always choose the design with the best ecological value practicable within the sites limitations (see Figure 1). There is a presumption to vegetated intertidal terraces (as a minimum) if a wall is failing).
Figure 1: Showing cross sections of typical designs (with photographic examples) in order of ecological value.

Figure 1: Showing cross sections of typical designs (with photographic examples) in order of ecological value.

  1. Ensure you design to correct guidelines for either full set back/creek management (see Figure 2), a vegetated intertidal terrace (see Figure 3) or a wall option, paying careful attention to the zone where vegeation is likely to grow between Mean High Water Neap and Mean High Water Sprng tidal levels.
  2. Approach multidisciplinary consultant/contractors (who have knowledge of geomorphologists) and work with local organisations, where they exist, with local knowledge and expertise in order to achieve a good product.
  3. Consider masterplanning early on in the design of your site;
  4. Look to surrounding area to influence your design (see archaeology and heritage as well as education, aesthetics and art).
  5. Design to enhance wildlife, planting and greenspace, including maximising value to fish.
  6. Design for safety and navigation, considering the navigational use at the location in question and how users will interact with the proposed structure.
  7. Consider access to the feature for both navigation (e.g. ladders, grab chains) and for maintenance and monitoring (e.g. locked or hidden gates) to facilitate removal of litter.
  8. Design for geomorphology and litter.
  9. Ensure retaining walls are engineered for the appropriate ground conditions, geology and land based loadings (e.g. soil, water, buildings, vehicles, etc.,).
  10. Design for sustainability and adaptability. Don’t use wire or non-biodegradable materials (eg: plastics or geotextile) in otherwise natural designs, wire with faggot bundles hasn’t been successful, for example.
  11. The lifetime of the structure needs to be the same as the projected lifespan of the development (this is particularly important regarding timber).
  12. Choose construction materials which have the greatest surface roughness to enable stable colonisation by surface-dwelling algae and plants eg: textured concrete, groves in timber. Follow guidelines for the use of  timber. If using concrete, consider use of concrete with a lower pH (eco-concrete).
  13. Do explore the use of innovative and differing materials and techniques using the general principles outlined in this document.
  14. Budget for monitoring and maintenance, including clearing of any collected litter.
  15. Include indemity/insurance. Note some parts of the design can have indeminity linked to one party and other parts can be linked to other parties.

Guidelines specific to full set back/creek erosion management
Guidelines specific to intertidal vegetated terraces
Guidelines specific to vertical wall options
Archaeology and heritage
Education, aesthetics and art
Wildlife, Planting and Greenspace
Safety and Navigation
Monitoring and maintenance
Sustainability and Adaptability
Use of Timber