ENVIROLOK
Stabilization of shorelines and banks along open water areas prevents erosion of upland areas . Bulkheads and revetments are examples of shoreline “ hardening ” and are traditional techniques that provide a hard substrate ( wood , stone , or concrete ) to fortify shorelines . However , these structures have the potential to result in erosion on adjacent upland areas , are costly to install , do not adapt to local conditions , and provide minimal aesthetic benefits to the surrounding area . While green infrastructure alternatives , such as vegetated buffers , can provide some relief to erosion issues along problem areas , some areas require more fortified solutions for mitigating issues with erosion . This has resulted in land managers exploring hybrid gray-green infrastructure approaches to provide the benefits of fortified shorelines and vegetated buffers .
ENVIROLOK
An approach frequently used on Kiawah Island , by the Kiawah Island Community Association ( KICA ), is the Envirolok system , a fully-engineered geotextile bag system designed to permanently stabilize slopes , waterways and shorelines . The system combines the stabilization of both interlocking , soil-filled bags and the roots of plants to provide a sustainable solution to shoreline erosion . The system differs from other hardened structures ( e . g ., concrete , wood , and stone walls ) because the integrity of the system increases as more plants colonize the system to bind the bags to the underlying native soils . The Envirolok system is designed to provide a permanent vegetated bank for use in a variety of applications .
Envirolok is recommended for use by both public and private entities , including the U . S . Fish and Wildlife Service which has assisted with the installation of these systems in the Charleston area . The manufacturers of Envirolok materials also have a staff accredited by LEED to provide assistance on installation projects . Consultation with professional engineers is required when considering the implementation of Envirolok systems so they are designed in accordance with County , State , and Federal permitting standards .
Site Selection
Areas along stream banks , tidal creeks , pond edges , and drainage outflows are suitable sites for installing Envirolok systems if the slope is deemed appropriate by their site evaluation team . Envirolok can be considered in some areas where bulkheads , revetments , or other gray infrastructure shoreline erosion devices can be located . These systems can be installed on slopes up to 50 feet high and to any desired width . On Kiawah Island , these areas are generally adjacent to navigable waterways or the critical zone . In order to permit any projects within these state and federally regulated areas , a critical line and jurisdictional determination will need to be conducted by the South Carolina Department of Health and Environmental Control ’ s Office of Coastal Resource Management ( SCDHEC OCRM ) and possibly the Army Corps . of Engineers ( USACE ), respectively .
Materials and Preparation
The interlocking system of Envirolok consists of bags filled with a soil type specified by the site geotechnical engineer . The bags are tan and made of non-woven geotextiles , which are secured with ultraviolet-resistant closure ties . The construction of the bags is more resistant to ultraviolet degradation , emits less heat , and are more aesthetically pleasing than the traditional use of black bags . The bags should be filled with a mixture of approximately 60-80 % sand and 20-40 % topsoil ( 80 / 20 ratio recommended by manufacturer ). The manufacturer suggests higher ratios of topsoil will reduce the efficacy of the system and result in slumping . The soil mix is not proprietary and the materials are readily available from local or regional sources around the project area . Together , this allows for longterm stabilization of shorelines by allowing installed plants to establish . In addition , the media will promote plant
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