Dams present a potential risk to downstream residents and properties. By law, they must be maintained to mitigate the risk of a breach . The embankments of earthen dams built in Central Queensland are often constructed with dispersive subsoil which makes them especially susceptible to rill and tunnel erosion. Establishment and maintenance of healthy grass cover and intact HDPE liners are key to successful, long-term operation.
The BeneTerra team provided annual dam maintenance services to maintain the integrity of these assets for coal seam gas operators in the Bowen Basin. The team employed skills in project management, civil engineering, heavy construction, soil science, agronomy and HDPE welding.
These turkey’s nest dams or ponds had been in service about 10 years and had been fairly well maintained. Yet, there were tears in the HDPE liners, sinkholes and rill erosion in the embankments.
The process began with an inspection by a civil engineer and a site supervisor. They walked each dam and made a detailed assessment of any defects or needed improvements. These were geolocated and marked as needed. The project manager created a proposed scope of work and submitted that to the client for approval. Once the approval was given, the team commenced that campaign in November 2022. The works were completed in 42 days and then inspected by an independent civil engineer.
The work consisted of:
- Slashing or mowing the embankments
- Remediation of 22 sinkholes
- Repair of erosion along anchor trenches
- Repair of erosion inside an unlined dam
- Adding a rub sheet beneath pipe on a liner
- 84 HDPE liner repairs
- Marking of the design storage allowance and mandatory report levels
- Replacing fauna egress devices
- Fence repair
- Installation of a life ring
- Soil amendment and seeding of disturbed areas
