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  • Solution
    Erosion Control Blanket
  • Location
    Merbein, Victoria
  • Industry

In early 2017 Vline experienced drainage issues along with the railway cutting in Merbein, positioned inside a 617.600 kilometre stretch between the Dunolly to Yelta Freight corridor.

Engineering firm GHD were engaged to investigate the concerns raised over the issue during a site visit on the 22nd of August 2017. Reports suggested that there was no evidence of slope instability; however, indicated that wind and water erosion were the primary factors causing the blockages within the crest drains. The erosion created large holes and scouring of the slopes, which created the fine silt, sand and clay particles that were accumulating in the crest drains.

This issue affected the ability for water to displace away from the train line, causing widespread moisture in and around the track ballast; this altered its structural integrity by impinging on the tracks ability to bear the weight of oncoming trains adequately. Due to the high-risk factors associated with the instability; drivers were required to reduce speed by 10-15km/h to ensure safe and effective movement across the rail line. To effectively resolve this problem, the drains needed to be cleared immediately, while the cutting required an extensive erosion control solution.

Issue: A revegetation strategy was suggested by GHD to combat the issues throughout the railway cutting; however, soil testing indicated that the primary sediment consisted of dispersive clay soil, which when dry, becomes airborne with wind erosion. Due to the low rainfall in the area, this option would have been a short term solution, and therefore, an erosion control blanket was the most viable resolution for the site.

Project Overview:
Spray Grass Australia (SGA) was approached in early October 2017, by Global Rail Australia on behalf of VLine, to undertake erosion control works. The project scope would entail stabilisation of the railway cutting through the means of supplying and applying an effective erosion control solution.

On October 21st, SGA’s environmental consultants inspected the site location, whereby a 3D Drone survey was conducted to accurately examine the land topography thoroughly and determine the amount of product required to cover the specified substrate area.

Upon inspection of the site, SGA put forward a proposal framework that articulated VLine’s industry commitment to maintaining the relevant Australian standards and requirements associated with the stabilisation of the road embankment and rail side cutting.

The following specified tender, complied with SGA’s ability to effectively provide an erosion control solution that would successfully stabilise the railway cutting:

• EcoArmour – Applied at seven tonnes per hectare and accompanied with a 10+ year guarantee
EcoArmour is an Australian designed and manufactured synthetic erosion control blanket that has been designed to be applied hydraulically through high-pressure hydroseeding plant and equipment. Once sprayed, it dries and sets in a matter of hours, providing extended high-shear resistant erosion control for up to 20 years of protection, depending on the clients specified application rate.

It is scientifically engendered with a blend of minerals, interlocking fibres and specialty binders to form a durable, non-flammable crust. The specialty binders adhere to and incorporate themselves into the substrate below, establishing a tough, resilient cover that is also flexible enough to move with the ground below it.

Based on observations recovered during the initial drone survey, SGA recognised that the most effective means of product application would be through, water cannon and hydraulic hoses attached to their mine compliant Hino FINN T170 HydroTruck. The management of these attachment’s provided SGA technicians with the flexibility to adjust pressure rates for application consistency, and uniform delivery of the erosion control blanket onto the substrate safely and efficiently.
Feature: This vehicle can store 7,000 litres within its holding tank, along with two in-built agitators designed to maintain a homogenous solution mix.

After extensive analysis and the implementation of safety and contingency procedures; works commenced with an initial 3D drone survey designed to map the area to a high degree of accuracy. This procedure provided significant data that assisted in determining the application area and rates for solution coverage. Data indicated that the 400-metre railway cutting height, ranged from one metre through to five metres, with angles gradients varying from 35 – 60 degrees. This procedure was essential in effectively fulfilling the client’s ten-year guarantee, by providing the accurate calculations indicating that 65.5 tonnes of EcoArmour would be required on-site for optimum product coverage.

Weather activity was another factor that was continually measured to ensure appropriate times were scheduled for application, due to high temperatures and humidity during this time of the year.
Due to the implementation of comprehensive processes and procedures, the 9,350m2 project was successfully undertaken during one on-site mobilisation, spanning over four consecutive days, from the 6th of March through to the 10th of March 2018.

SGA overcame several challenges throughout the duration of the project with the assistance of safety and quality contingency procedures. The following problems were recognised and addressed promptly and efficiently as possible:
• Access issues were prominent early into the implementation stage of the project with hose’s
unable to manoeuvre efficiently within the corridor cutting. The team were able to think
proactively to combat this problem by implementing altered application positioning.

• The railway cuttings contained protected native plant species, which required the SGA technicians to apply the product meticulously around the plants, without impairing. This issue was approached by applying the product at a lower application rate, to ensure that the plants weren’t disturbed in the process and that the product membrane effectively established contact with the substrate.

• The embankment located at the top of the cutting required compacting before the application of the erosion control blanket; however, external contractors had not effectively completed this to SGA’s company standards. The team took the initiative to combat the problem with the use of their HydroBond product to harden the surface and provide a sufficient base for the EcoArmour solution.

Average Weather conditions – Infographic: Temperature (L: 16.8 °, H: 33°), Wind (L: 8.8 km/h, H21.6 km/h), Humidity (L: 16.6%, H: 52%)

• Onsite technicians were confronted with high temperatures and humidity, exposing them to potentially harmful work health and safety risks. This matter was treated incredibly seriously with a Fatigue and Heat Management Plan appointed throughout the duration of the project to prevent the likelihood of dehydration and or heat stresses.

Vline was pleased with the erosion control solution that SGA was able to provide on the railway cutting. The product held up exceptionally well and eliminated further issues associated with erosion on site. The safety and integrity of the rail line bearings are no longer compromised; therefore, risk levels on-site remain extremely low. The project effectiveness stemmed from the constant communication with the client, which maximised on SGA’s ability to meet the client’s requirements within the stipulated timeframe.

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