Two large-scale steel corrugated Armco culverts located beneath an access road at a Queensland wind farm had suffered serious damage during a tropical cyclone in March 2018
The culverts, measuring 2100mm diameter and 24m long, were situated beneath the road and within an embankment made from compacted bedding material and backfill supporting the culvert pipes.
Torrential rain had interrupted construction of the culvert headwall, resulting in deformation of the culvert crown and caused erosion due to soil fines washing away from the embankment. More than 24 hours after the rain deluge, water continued to flow through the embankment that was supporting the road, raising concerns about the ongoing stability of the road and culverts.
To prevent the damage from worsening, the ground needed to be consolidated and the embankment stabilised. While the road was determined to be structurally adequate for continued use, remediation works were required to ensure the long-term performance and durability of the culverts, of the embankment supporting the access road and of the existing services located within the fill. Works needed to be undertaken quickly in order to be completed before the beginning of the annual wet season in November.
With extensive experience in delivering fast, efficient and effective remediation solutions for culverts and underground pipes, Mainmark was contracted to strengthen the ground surrounding the culverts and support the access road that ran above them.
The desired outcome of the work was to strengthen the weakened backfill surrounding the culverts to a thickness of 500mm-1000mm.
This was needed to ensure protection against erosion, to help prevent water infiltration into the bedding and embankments, as well as keep this road open in order to access specific turbines at the wind farm.
Teretek® engineered resin presented an ideal solution for the required scope of works, due to its unique ability to increase ground bearing capacity without damaging the already compromised culverts. Teretek® has no detrimental effects on ground water, soil quality or local wildlife and is backed by a 50-year product warranty.
In a process similar to keyhole surgery, 900kg of the Teretek® polyurethane resin was injected through very small tubes into the affected ground surrounding the culverts. The engineered structural resin rapidly expands, to re-establish ground support without impacting the compromised culverts. The way in which the resin interacts with the soil helps prevent water ingress and erosion, arresting water movement and assisting the long-term strength of the culverts and access road.
Mainmark technicians were able to carefully plan the resin injection locations so that they targeted the treatment zones within the steep embankment safely, caused minimal disruption to the wind farm or blocked road access across the top of culverts. This provided an extremely quick and efficient remediation solution for treating the issue before commencement of the wet season.
With three technicians and a self-contained Mainmark rig onsite, works were completed within just two days. The project provided an extremely cost-effective and time efficient alternative to replacing the culverts, which would have been disruptive for the wind farm operators. Teretek®successfully strengthened the embankment supporting a vital roadway that provides the only vehicular access to two wind turbines, avoiding road closure and disruption to operation of the wind farm.
Project Resources & Downloads
Teretek® Repairs Damaged Culverts at Far North Queensland Wind Farm
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Voids Under Sewer System Filled Using Teretek®
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Mainmark Ground Engineering Pty Ltd
ABN: 51 606 182 503