Geotextile Grout Mattress Systems – Why They Are an Option For Coastal Erosion

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Whether global warming is the cause of climate change or not, recent extreme weather events are an observable fact. There is no doubt they have put additional pressure on coastal environments.

A large proportion of the Australian population and many parts of the world live in coastal communities and so coastal erosion is a major concern.

Most available protective solutions against erosion-causing forces are either too expensive and/or likely to have adverse consequential effects on other parts of the coastline. University of NSW coastal engineering studies attest to this. A seawall built at point A, can change the forces at work at point B further up or down the coast.

It’s a complex system that cannot be universally addressed by man-made solutions.

So without interfering with nature’s forces by building sea walls, reefs, or similar, can buffering of existing coastal landforms provide some remedy,interim or longer term, using a relatively low cost approach that geotextiles provide?

Geotextile grout mattress systems have been extensively used in many areas relating to water and water erosion, including the protection of embankments on roads and bridges, wharves and harbours. Its versatility is further demonstrated by its use in lining dams, ponds, waterways, channels, spillways, drains and culverts.

It’s also been used for sea walls and beach protection in circumstances of mild wave action.

Generally these are fairly major works initiated by the relevant authorities.

However, householders under threat or potential threat from coastal erosion may wish to address this independent of authorities such as the local council. Among other things, there is likely to be a long running argument with council over responsibility to take action. Even the recent “win” in court by an Australian resident in Byron Bay over the local council took 8 years!….just to protect his property. His proposed action that involved using rockfill where erosion was occurring

was not viewed favourably by council for reasons within their supposed authority.

Traditional erosion protection systems such as rock fill are usually cumbersome and expensive.

There is an erosion protection system that is fast and relatively low cost that householders may be able to utilise, either individually or as a group, without the need to get council endorsement.

It is a geotextile product called ‘Growth Matt’ which provides a solid stabilising structure much in the nature of a garden bed, as it allows vegetation to establish and grow through its panels. The area would have to be suitable for appropriate vegetation growth if this particular style of geotextile is to be used. Each situation would need to be assessed in consultation with a qualified installer as it involves a technique of pumping the geotextile fabric with grout.

One consideration would be accessibility to the site for ready-mix concrete supply and the placement of truck-mounted grout pump. The specialised grout mix does allow it to be pumped over distance but there are limits.

No major earthworks are normally required and, given the scope of the work, no council approval should be required.

Now if you want the council to pay it’s likely a different issue, but maybe councils should be exploring such methods in addressing the very serious issue of coastal erosion in any case. Perhaps such micro measures are, if not the answer, a step in the right direction.

This may not be sustainable protection in the face of rising sea levels or more extreme weather events, but given the value of coastline buildings/residences, its worth exploring if only as short term or interim measure. In this regard I’m reminded of the old saying” a stitch in time saves nine”

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