Rock Bag Applications

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Rock Bag Applications – Rock Bag Filter Units

Rock Bag Filter Units are long lasting, durable and UV resistant ! They are simple, fast and very very effective for a variety of common and complex situations where environmental and infrastructure protection is required, particularly erosion and scour control. A sample of common rock bag applications have been listed below for reference, more details and case studies are available upon request.

Environmental – Vegetated Armour

Rock Bags Filter Units being installed into landslips and areas prone to constant erosion, can be vegetated to seamlessly blend with local landscapes while maintaining their robust integrity and function. Quite often the rock bags become filled with silt and sediments creating a natural environment where mother nature takes over completely covering the structure with vegetation.

A vegetated rock bag armouring system is highly effective as the root systems plays a crucial role in stabilizing soil and preventing erosion. Vegetation in a retaining wall acts as a natural reinforcement, securing the soil in place and reducing the risk of slope failure. The roots bind the soil particles together, enhancing the structural stability of the wall and minimizing erosion caused by water runoff.

Once established plant foliage creates another UV barrier over the exterior netting.

It’s also possible to hydro seed rock bags to encourage rapid greenery and fast track penetration of the root systems.

Once high velocity water flows are experienced such as flash flooding the vegetated rock bags maintain stability while protecting the embankment from erosion and potential collapse.

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Can Rock Bag Filter Units be utilized in other natural environments?

Rock Bag Filter Units are safe to use in the environment utilising locally available media like river stone, qurried rock and even coral. With very little disturbance to embankments or riverbeds during placement. Rock Bag Filter Units can be deployed with minimal environmental impact of noise, dust, silt or clearing.

In fact, many applications are deployed directly from the back of trucks, eliminating the need for onsite filling or large laydown areas. Other applications for environmental protections are to fill Rock Bag Filter Units with limestone rock and when placed in watercourses can naturally reduce acidity improving water quality. Rock Bag Filter Units used in conjunction with our Water Restore ECO Velocity Bags which passively remove up to 99% of PFAS and other contaminates from our waterways.

Coastal Protection

Rock Bag Filter Units have proven to offer superior advantages for coastal environments.

During inclement weather, Rock Bag Filter Units successfully protect coastlines and beaches from destructive seas by dissipating wave energy rather than deflecting.

The deflection causes under mining, suctioning loose material and small particles away on the back flow, these smaller particles help keep the structure sound.

Fortunately, rock fill contained inside the bag absorbs wave power where traditional methods such as concrete structures cannot offer this advantage.

Gabions, although similar by containing rock, are expensive to install and are short term measures in coastal environments as the wire body suffers from corrosion thus compromising mechanical viability of the structure. Ultimately the structure becomes dangerous, ineffective and will eventually collapse and require replacing.

Rock bag filter units offer flexibility in design and installation. They can be tailored to suit specific coastal conditions, including varying wave heights, tidal ranges, and sediment characteristics. They can also be used in both temporary and permanent applications, allowing for adaptability to changing coastal dynamics.

Rock bag filter units are considered environmentally friendly as they utilize locally available materials and do not involve the use of harmful chemicals. They blend with the natural coastal environment and provide habitat opportunities for marine organisms.

Rock bag filter units have been successfully employed in various coastal applications, including beach nourishment projects, shoreline stabilization, protection of sand dunes and erosion control of tidal creeks and rivers.

They offer a cost-effective and sustainable solution for managing sedimentation and protecting coastal infrastructure while preserving the natural coastal environment.

Harbours, Ports And Sea Walls 

With the demand for larger and deeper berthing facilities at Harbours and Ports constantly increasing to satisfy the expansion of world trade, applications for Rock Bag Filter Units remains vast within the marine environment. From anchoring cables to the sea floor to ship berthing ports around the world, the ability to conform to a set design and execute rock armouring installations to pin point accuracy equates to projects been on time and on budget.

The unrelenting scour around pylons, piling walls, bridges and other marine infrastructure caused by large vessels arriving and departing harbours and ports, costs Port operators millions of dollars every year to repair scour damage caused by bow thrusters and propellers from large ships.

Despite being a temporary solution and requiring constant replacement, installing riprap has been the only option available. As individual rocks, Riprap can easily wash away or sink into heavy sediment. Furthermore riprap looks unsightly above the water level.

Rock Bag Filter Units offer marine engineers a plausible countermeasure for long term scour protection. The contained rock inside the heavy duty netting  eliminates undermining of pylon foundation and compromise of the pylons structural integrity. In essence the rock bags are extremely stable and effective in high velocity water flows.

Other applications for marine environments include:

  • Construction of Groynes
  • Scour protection of embankments
  • Construction of sea wall
  • Toe scour protection wharf / jetty walls

Bridges & Pylons

The durable construction and weight makes rock bags resistant to being displaced by flowing water, safeguarding the structural integrity of bridge components.

Bridge walls and pylons are under constant attack from daily tidal flows, flash floods and constant traffic from commercial and recreational vessels. The persistent and turbulent water erodes foundations leaving them exposed and at risk of failure.

The wide foot print and mass weight of rock bags are the perfect solution for protecting important infrastructure such as road and rail bridges from scour and erosion. Rock bags conform to the shape of the terrain and are versatile in various environments, including riverbanks and underwater applications. Their flexibility allows for easy adaptation to irregular surfaces and different water levels.

Rock bags can be designed and arranged in ways that blend with the natural landscape, making them aesthetically pleasing and preserving the visual appeal of the surrounding area.

By preventing scour and erosion, rock bags help maintain the integrity of bridge foundations, reducing the risk of structural damage during extreme weather events.

Temporary Works

Rock bag Filter Units are the perfect construction product for temporary works projects.

Rock Bag Filter Units can be rapidly filled, positioned into place with a crane or excavator, utilised for the desired period then removed away from site with ease.

The single lifting point makes the process simple and effective while leaving no impact on the natural environment.

Applications are broad including:

  • temporary cross over for vehicles
  • drainage and silt control
  •  access road to project sites

  • retaining wall system
  • shoreline protection on coastal fronts

  • pre or post extreme weather events river, creeks, bridges etc

  • coffer dam for shoreline restoration

Another key benefit of utilizing Rock Bag Filter Units is the ability to move them into another project or on-sell them to recover costs.

The bags can be loaded by crane and transported by trucks to another location.


Rock Bags Filter Units once installed into marine environments provide shelter for many types of organisms.

Over time, marine organisms such as algae, barnacles, mussels, and other filter feeders can attach themselves to the surface of the Rock Bags, forming what is known as a biofilm. This biofilm provides food and habitat for small organisms such as snails and small fish, which in turn attract larger predators such as crabs and fish.

The rocks within the bags can create crevices and other spaces that can provide shelter for marine life. Small fish and crabs can hide among the rocks and crevices creating important habitats and help to protect the overall health of marine ecosystems.

These images were taken when a series of rock bags were removed from a marine port 1 week after a stability test was initiated and completed. The bags were removed when the testing concluded only to discover many marine creatures had already inhabited the rock bag filter units.

Filling Method

Rock Bag Filter Units are fast to fill and easy to install whether it’s above ground or below sea level. With precise sizes being 1, 2, 4, 6 and 8 Ton bags, therefore calculated dimensions, volumes and weights can be easily incorporated into an engineer’s design.

In addition, the nature of the netting material allows for a flexible structure, therefore the Rock Bags settle into contours of existing landscapes or sea floor with little to no preparation of footings.

The circular design of our  filling jigs increases daily output by 30% and maintains the best possible shape of the filled rock bag units for safe lifting and placing.

Advanced Fibre Materials

The extensive strength and life expectancy of Rock Bag Filter Units can be attributed to the high-tech netting fibres, manufactured in HDPE (High Density PolyEthelene).

HDPE netting is designed to withstand harsh marine environments, including exposure to saltwater, UV radiation, and severe weather conditions.

One of the advantages of HDPE marine netting is its high strength-to-weight ratio. It is lightweight and flexible, yet strong and durable, making it ideal for use in marine environments. The netting is also resistant to abrasion, tearing, and chemical degradation, making it long-lasting and reliable.

Overall, HDPE netting is a versatile and practical solution for a wide range of applications, providing strength, durability, and protection in harsh environments.

Rock Bag Filter Units are manufactured under strict quality control measures in conjunction with regular laboratory testing for strength, abrasion resistance and UV stability proving they are safe, reliable and offer industry leading quality and life expectancy out in the field.