Secutex® Soft Rock on a par with dunes at West Links
Naue’s Secutex® Soft Rock sand containers have provided a soft-engineering solution at Scotland’s historic West Links Golf Course, where the rate of coastal erosion has been a cause of concern for several years.
Rising sea levels, reductions in sand deposition, and the resultant lowering of beach levels, is increasingly impacting on the UK’s coastlines. At North Berwick, in East Lothian, the prevalence of northerly winds and storm surges has increased the rate of erosion; particularly affecting the dunes along the southern banks of the Firth of Forth.
At the North Berwick Golf Club, remedial and preventative measures have been undertaken over many years to protect the world-renowned West Links Course which follows the coastline on a north-facing land projection, on the south bank of the Forth estuary.
Coastal protection with geosynthetic sand container solution
The region derives significant economic benefit from the existence of this historic championship course where golf has been played since the 17th century. Founded in 1832, North Berwick Golf Club is the 13th oldest golf club in the world and only St Andrews hosts a club which has played continuously over the same course for longer.
A fixed point photography system had been in place since 2014 to monitor the effects of coastal erosion on the dunes, and this photographic record was documented in a feasibility study carried out prior to the appointment of engineering consultancy EnviroCentre.
Managing the sensitive coastal protection project was Principal Consultant Neil Gordon, from EnviroCentre’s Edinburgh office, and the contract to undertake construction of the sand-based structure, which would replace the lost coastline, was awarded to environmental engineering specialist McGowan Ltd.
For the heart of the structure, EnviroCentre specified the use of Naue´s Secutex® R601 Soft Rock sand containers – large, sand-filled, geotextile bags manufactured from nonwoven, needle-punched Secutex® – to provide filter-stability and scour protection for the dune structures. A total of 850 individual bags were filled on-site with imported sand, machine-sewn to seal the open end, and installed in alternate overlapping courses, in a ‘brick-bonding’ pattern. Delivered to site in flat format, the containers measure 2380mm x 1450mm but, once filled with around one cubic metre of sand, become rectangular blocks, approximately 2 metres long with a cross section of 1250 x 450mm.
Naue’s geotextiles are widely used in the construction of coastal erosion control structures and are designed to allow the passage of water, in both directions, but filter fine sand particles; providing a highly effective and economic method of construction. The filter-stable nonwoven geotextiles can be used to provide robust, flexible construction elements that are similar to the natural coastal and marine environment but with greater erosion control.
Sand was initially excavated from the dune by McGowan’s installation team and then banked to a natural slope. Lengths of Naue’s Secutex® H were then rolled out directly onto the sandy slope prior to installation of the sand-filled containers.
The layered structure would effectively reclaim land which had been eroded, and provide protection against future erosion. To complete the structure, a layer of Secutex® R1201 was wrapped around the sand along the crest of the dune before being covered by a top dressing of sand, at least 1 metre deep, in preparation for planting Marram Grass to re-establish a natural dune environment.
Secutex® H is manufactured from UV-stabilised polypropylene. It is a single-layered, non-woven, needle-punched staple fibre geotextile, and specifically designed for use in hydraulic engineering applications. The product is highly resistant to abrasion, and is supplied on 6 metre wide rolls, with weather-proof and UV-resistant outer wrapping for transportation and storage. On-site, rolls are simply deployed using a loader fitted with a spreader bar.
Placement can be carried out under dry or wet conditions, and any cutting required can be achieved using standard tools.
Secutex® H is a high quality, robust and filter-stable geotextile; it can be supplied as a single or multi-layer textile and is manufactured to a wide range of specifications, for numerous applications, in coastal and river erosion defence systems. Its robust structure offers resistance to puncture from point loads and can accept direct installation of heavy rock armour; McGowan’s went on to use the same material further along the coast, adjacent to the second fairway, where rock armour was being reinstated to protect a timber revetment.
Naue’s Secutex® geotextiles offer robust and resilient solutions; facilitating the implementation of innovative approaches to coastal protection whilst permitting the restoration of natural ecological processes.