Fig.7 Where 1=Greenstick piles; 2=Pivoting adjustable shafts; 3=Panel;4=Permeable or non-permeable membrane; 5=Reclaimed pulp.A=Starting water level; A-A1=Tidal rangeThe Greenstick wall construction phases are as follows:1.Vertical screw piling of Greensticks as per stakeout axes2.FRP panels inserted into one row of Greensticks via the keyways to form a wall3.Waterproof geotextile membrane set into position4.Greenstick joints unlocked, FRP panel wall positioned to required angle & made firm by connecting to the supporting row of Greensticks to form a secure structure5.Dredged soil transferred over the Greenstick wall to fill the voidGreenstick piles are capable of holding high vertical and horizontal loads. The slope of the wall reduces the active earth pressure on the FRP panel, reducing the horizontal force and keeping the Greenstick in place. The Greensticks and the FRP panels can serve as a permanent structure or have the added benefit of being fully removable and re-utilised elsewhere if required.The benefits of using Fibre Reinforced Plastic (FRP) panelsFRP has a number of advantages compared with materials traditionally used in hydraulic engineering, for example:oUnlike concrete, low water absorption makes FRP resistant to freezing and thawingoFRP tensile strength is higher than that of steeloFRP can be manufactured with significantly higher abrasion resistance than that of concrete or steeloUsage of lightweight FRP is likely to reduce construction time and costoFRP, not being subject to chemical or electrochemical corrosion, is suitable for marine hydraulic structures and is cheaper than concrete or steeloFRP has the thermal conductivity of wood, preventing ice from forming on the surfaceoFRP can be manufactured in any colour making it more aesthetically pleasing than other materials
GREENSTICK TECHNOLGY FOR DREDGING, PROTECTION FROM COASTAL EROSION & FLOOD DEFENCEGreenstick technology offers a brand new solution for a wide range of applications that require mooring in water. The Greenstick is a screw pile with a patented lockable and unlockable joint, allowing vertical deployment and the ability to set the required angle once the Greenstick is securely in place. The Greenstick can be manufactured to include a keyway which will allow FRP panels to be inserted between Greensticks to build retaining walls of different shapes, size and purpose. (See Appendix 1, Fig.7))The Greenstick can provide economic and environmental solutions in the following areas, although there are many other uses not listed here:1.Creation of artificial territories for commercial or environmental use2.Protection from coastal erosion3.Creation of embankments and bank protection resistant to ice loads4.Effective and less environmentally damaging disposal of dredging soil5.Speeding up the current “pre-loading” method of dredged soil6.Efficient removal of sediment build up in non tidal waters7.Temporary or permanent cofferdams or breakwaters8.Protection of coastal land from intense winter storms9.Provision of clear shipping navigation channels10.Protection of earth dams and areas from flooding1.Creation of artificial territories for commercial or environmental useThe Greenstick wall technology may be used in the creation of artificial territory to be utilised for commercial gain or for using the newly formed landmass for environmental and natural purposes. The Greenstick wall system is less invasive than traditional methods of land reclamation and, due to the lightweight nature of the simple design, likely to be a quicker and less expensive option.The image below (Fig.1) of the Nordsee Luftbilder project, shows an example of an existing method of creating artificial territory where the gap in the structure allows the ebb tide to escape whilst retaining as much of the silt as possible within. A Greenstick wall could replace this method and could function without need for the gap, by sloping the walls at an appropriate angle, the ebb tide would be able to flow freely over the top of the structure whilst more of the silt would remain inside, thereby speeding up the process, saving both time and cost.
Fig.1 Nordsee Luftbilder project
A particular example of where the Greenstick wall technology would be beneficial is in the Ukraine where an alluvium strip of territory between the coastline and existing land might be the only option to meet the legislation laid down by Seaport Law  which requires a 100 metre water protected zone between the coastline and newly reclaimed land used for private commercial gain.2. Protection from coastal erosionIn practice, a number of methods are used for passive protection of the coast from erosion. The advantage of using Greenstick technology lies in the ease and speed of construction, reliability and lower costs. Due to its relatively simple design, it is possible to install fibreglass groins, beams, piers, breakwaters, freeboard, flooded,complete and incomplete profiles selected on the basis of wave loads at the construction site. According to the patent , Greenstick piles can be of different types and immersed in different ways; screw, driven, suction etc. This allows the Greenstick pile to achieve the bearing capacity on horizontal loads of tens of tons, enabling the technology to be used not only in the applications described herein but also in port and offshore structures.The image below (Fig.2) shows a traditional coastal protection project in Australia. Utilisation of Greenstick wall technology would eliminate the need to transport tons of rock to site and reduce resource required in the construction process.
Fig.2Australian coastal protection project
3. Creation of embankments and bank protection resistant to ice loadsSince the embankment slope of a Greenstick wall is made from FRP, it will be unaffected by icy conditions. In the case of ice drifts, the ice fields will glide over the surface of the FRP wall without destroying it. FRP sheets are as strong and durable as steel; they are widely used in construction as walls for buildings, for roofing, bridges and road surfaces. In the United States and Europe, FRP panels are used as the span beams for railway bridges, quay and hydropower installations. A prime example of the use of FRP panels in construction is in Russia where a fibreglass seawall was successfully built and used for a number of years along the stretch of coast between Adler and Tuapse.4. Effective and less environmentally damaging disposal of dredging soilIt is well known that cleaning the bottom of a river or estuary by dredging and dumping the soil at sea is environmentally damaging, primarily because the discharged slurry is spread by waves and currents for tens of kilometres, destroying essential sea bacteria through deprivation of oxygen. It is also financially costly, given that the soil has to be transported from the site to the sea by land vehicles or sea vessels both of which incur the additional costs of crew, fuel and time. Since the volume of repairs and new digging in ports and channels is increasingly annually, so the costs, both environmentally and financially, will also increase if the dumping of dredged soil in the sea continues. The Greenstick wall technology can be used in the development of a more cost effective and environmentally sound solution, that being the adoption and improvement of the “pre-load” method where dredged soil can be utilised on site and retained via the Greenstick wall. (See point 5 and Fig.3 below)5. Speeding up the current “pre-loading” method of dredged soilGreenstick wall technology can be used to accelerate reclaimed soil consolidation. Fencing the walls of the reclamation area can be done by mounting the wall panels on the surface of the reclaimed soil. (See Fig.3a). Utilisation of the Greenstick walls is likely to be significantly cheaper and quicker than the existing method of creating soil dams by bulldozers. (See Fig.3b)
Proposed Greenstick Technology
Existing pre-load method
Fig.3 b) the existing method of creating embankment dams using reclaimed soil where, 1 = earthen dam; 2 = reclaimed pulp; 3 = dam reclamation 2nd layer; 4 = draining layer; 5 = slurry pipeline
6. Efficient removal of sediment build up in non tidal watersLike the dredging of ports and approach channels, cleaning silt and sediment from the beds of reservoirs and other non tidal waters presents an urgent environmental challenge.Siltation of reservoir beds leads to a number of environmental problems; an increase in ground water levels to adjacent areas, the extinction of benthic biogenesis, overgrowth of coast reeds and further eutrophication of water bodies resulting in the proliferation of algae which causes depletion of oxygen and the death of other organisms such as fish. Clearing the beds of water bodies leads to the formation of fresh water springs and revitalises the biosystem. The Greenstick wall technology can be used to create an artificial territory to allow ground clearance to take place and protect the area.7. Temporary or permanent cofferdams or breakwatersBuilding on the coast runs the risk of erosion by storms. The Greenstick technology allows the protection of the site during the period of construction from damage and the ablation of the construction materials by the sea. After construction has been completed, the protective Greenstick wall and piles can either be dismantled and removed or left in place to further protect areas liable to flooding or from storm attack. Earth dams can be strengthened by use of the Greenstick wall (any passage of water over an earth dam will degrade it very quickly causing awater fall and its imminent self destruction) , in emergencies, additional height can be added to provide extra protection , weak exposed surfaces can quickly be protection if required , this again is a simple quick process.8. Protection of coastal land from intense winter stormsGreenstick walls can be used to protect coastal land or resort areas from the damaging effects of intense winter storms during which soil and beach sand is taken back into the open sea and landmass is subsequently reduced. The installation of a Greenstick wall would retain coastal or reclaimed land by acting as a breakwater to reduce the wave impact and reduce coastal erosion. (Fig.4 below)
Fig. 4Construction of Greenstick wallsfor protection of coastal landfrom storms
9. Provision of clear shipping navigation channelsSloping Greenstick walls can be set at a specific angleused to reduce the build-up of sediment in shipping channels due to currents and storms, thereby ensuring minimal disruption to valuable marine industries. (See Fig.5)
Fig. 5 Greenstick navigation channel protection from sediment
10. Protection of earth dams and areas from floodingThe Greenstick walls are able to provide protection from floods to earth dams and, significantly, an unobtrusive, straight forward solution to areas liable to flood, which is a global problem. Greenstick walls can be installed either permanently or temporarily, thereby saving repair costs. For general flood protection, the Greenstick walls can be mounted along riverbanks or shorelines. During periods of flood, the walls can be raised and lowered once the threat of flood has diminished. (See Fig.6 below)
Fig. 6 Protection against flood wall Greenstick
SUMMARYThe Greenstick solutions outlined above provide a selection of potential applications for this brand new and much required technology. As countries worldwide continue to put in place more stringent rules and laws governing heavy engineering and its’ effect on the global environment, new, less invasive technology will become increasingly necessary. The Greenstick pile alone provides many solutions for those industries requiring a mooring device but, with the inclusion of the FRP Greenstick wall, can replace much of the environmentally detrimental methods that are presently the only ones available. RESEARCH WORKResearch work and the testing of Greenstick piles has been carried out by The University of Hull in the UK and by The Norwegian Register of Shipping Veritas. REFERENCES1.Patent GB 2500322 A 2013 – David West & Gennady Meltsov2.The Law of Ukraine on sea ports – June 20133.Recommendations for the design of artificial territories formed by refilled soft soils of marine dredging - AV Skhola, AS Marchenko, AK Posuhovsky, GI Meltsov, TI Rabochaya. MAGVT, Odessa State Academy of Civil Engineering and Architecture Odessa1996APPENDIX 1 - GREENSTICK TECHNOLOGY USING FRP PANELSThe image below (Fig.7) demonstrates how Greenstick technology can be used with FRP panels to create a retaining wall, in this case to create an artificial territory: