Biohavens – the only truly bio-mimicking floating wetland- Case Study #9 – marine applications

31 October 2015

The BioHaven range of floating wetlands, also known as floating islands, provides a wide range of wetland aesthetic, habitat and treatment options designed from nature.  DH Environmental Consulting (Pty) Ltd (South Africa) has been partnered with Floating Island International, the designers of the BioHaven range, since 2008.  Over the next while our blog will document some Biohaven case studies.

9. Marine Environment Case Study

Project Location: Elfin Cove Area, Southeast Alaska, USA

This case study demonstrates the capabilities of patented BioHaven® technology to function in a harsh marine environment. The purpose of this application, which was the first seawater evaluation of the BioHaven floating treatment wetland (FTW) from Floating Island International (FII), was to study plant survival, biota colonization and island durability under marine conditions.

Two BioHaven islands were launched—a large module at Port Althorp (the “Port Althorp” FTW) and a small module in a private setting near Elfin Cove (the “Hobbit Hole” FTW). The larger island was moored to a piling at one end and chained to a mooring block at the other; the smaller island was tethered to an existing dock with nylon line. The Port Althorp FTW was constructed as a dock, with Trex decking applied to the top surface.

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Results

  •  The BioHaven matrix was not adversely impacted by exposure to seawater and Alaska wintertime temperatures/wave action
  • Numerous marine biota, including mollusks, starfish, worms and filter feeders such as anemone, populated the BioHavens. Several species of kelp also took up residence.
  • Perennial plants survived the winter and reemerged in the spring.
  • Both BioHavens remained buoyant under snow loads up to five feet.
  • The BioHavens remained intact with up to two-foot waves. The Port Althorp BioHaven was towed five miles in the summer of 2009 to the Hobbit Hole location to replace an existing section of dock. It is still in use and performing well.
  • Boats were able to tie and moor to the BioHaven FTW.

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