Abyss – Underwater Sewerage Inspection

The Issue at Urban Utilities

The Norman Creek siphon (Brisbane, Australia) was refurbished in approx. 1974.? It is designed to transport sewage under the Brisbane River into the S1 trunk system to Eagle Farm Pump Station, and then on to the Luggage Point Sewage Treatment Plant.?

The siphon runs under the Brisbane River from Norman Creek to New Farm, and comprises two concrete shafts which run deep underground with the horizontal section beneath the Brisbane River approximately 318 metres long (1,043 feet). The current water levels are approximately 36 meters-39 meters (118-128 feet) below the access point.

The siphon is currently filled with potable water, instead of being in its dry state.? As a result, the asset cannot be inspected via traditional means. The condition of this asset is unknown, and sending divers to inspect the asset presents a significant safety risk.

The Solution

Deploy a ROUV to capture closed-circuit television (CCTV) footage and still images of the asset.

The Pilot

The pilot was conducted in two phases. Phase 1 was an exploratory activity to determine the feasibility of deploying a tethered drone into the siphon. Phase 2 included:

  • Internal inspection of the siphon through the provision of tethered drone
  • Location/identification of interesting features/features of concern
  • Condition of internal fixtures and features
  • Detection of ingress points
  • Condition assessment report
  • 3D model

Pilot Results

Urban Utilities invested approximately AUD70,000 (USD42,000) of which 50% was funded under arrangements delivered in the Grant Deed between the State of Queensland and State of Nevada.

The underwater inspection was undertaken using a submersible fitted with the Abyss Solutions imaging technology, which comprises a computer vision camera, integrated lighting, and data capturing software. This allowed high-fidelity data representation in turbid and low light environments. A site inspection was undertaken to determine access conditions and water quality parameters.

The submersible was lowered down two access shafts and controlled through a tether by a pilot located on the surface. The submersible navigated along the obvert of the tunnel, with a downward-facing camera that captured high fidelity images of the visible surfaces of the twin pipelines.

Abyss Solutions delivered the outcomes of the inspection via a web-based database. The database houses:

  • siphon characteristics, including:
    • details (location, location coordinates, length, and diameter)
    • construction profile
    • access profile
  • inspection details (date, time, team, weather conditions)
  • scoring guide/legend
  • overall siphon condition score

Abyss Solutions also provided a condition assessment and score for individual elements:

  • tunnel walls
  • mild Steel Cement Lined (MSCL) pipes & protective coating
  • pipe supports
  • submarine cable

A multi-criteria condition assessment based on the IPWEA Condition Assessment & Asset Performance Guidelines was applied. Each element was assigned a condition grade ranging from ?0-not rated? to ?5-very poor?. A weighted average used to assign the overall reservoir condition.

Abyss Solutions also constructed a 3D digital model showing the internal configuration of the siphon. The model was produced using data from the inspection and includes annotations. The method of delivery via a portal exceeded expectations.

Further Adoption

The adoption of this technology as a business-as-usual solution is under consideration.

About the Technology

Abyss Solutions, located in Sydney, Australia was founded by four scientists and engineers from The University of Sydney in 2014. Abyss is a robotics company that combines the latest innovations ROUVs with state of the art data analytics to provide a safer, easier, and more comprehensive underwater inspection, allowing for correct asset management decisions.