Subsea Maintenance
Project Overview
Indianic Group Pty Ltd was engaged by Red Rock to deliver a critical subsea scope offshore, North of Bunbury, WA.
The project focused on the replacement and upgrade of the offshore treated wastewater (TWW) diffuser system and required specialist commercial diving capability to locate, remove, and replace the diffuser in challenging open water conditions while ensuring the integrity of existing subsea infrastructure.
In addition, Indianic was tasked with assessing the structural condition of the diffuser support frame and photo documenting the surrounding subsea environment.
Services Provided
Indianic delivered a full‑scope marine and diving program focused on the inspection, refurbishment, and replacement of an existing subsea diffuser system.
- Location of the existing TWW diffuser
- Detailed underwater visual inspections
- Cleaning of the existing support structure
- Non-destructive testing (NDT) of the support structure
- Cathodic protection potential testing
- Anode condition assessments
- Extensive subsea photographic survey
- Removal of the existing diffuser assembly
- High-pressure internal pipework cleaning (pigging)
- Installation of a new diffuser
- Installation of a new tubular support system
The works involved detailed underwater assessment and condition verification of the diffuser and supporting infrastructure, including corrosion protection performance and structural integrity, supported by comprehensive visual and photographic documentation.
This was followed by the safe removal of the existing diffuser and restoration of internal pipework capacity through high‑pressure cleaning. The project was completed with the installation of a new diffuser and tubular support system to reinstate long‑term operational functionality.
The Challenge
The project was undertaken in an open ocean at approximately 8 metres of water depth with extremely low visibility, creating significant operational and safety challenges for the dive team.
Upon inspection, it was identified that the existing diffuser support structure did not align with the as‑built drawings supplied. This discrepancy required rapid reassessment of the installation approach and on‑site engineering solutions, all while operating in a live marine environment.
Accurate installation, minimising downtime, and maintaining environmental compliance were critical to project success.
The Solution
Prior to commencing diving operations, Indianic ensured all required isolations to the existing diffuser were implemented and undertook a thorough review of the scope of works.
Commercial divers successfully located the diffuser in very low visibility conditions and carried out a detailed underwater inspection.
When the existing structure was found to differ from supplied drawings, Indianic’s dive supervisors and engineers developed practical, site‑specific solutions based on the actual configuration encountered. The structural integrity of the support frame was assessed, including cathodic protection and anode condition.
External high‑pressure water blasting was performed to remove marine growth and allow safe disassembly of components prior to the existing diffuser assembly being removed.
Indianic then undertook high‑pressure internal pipe cleaning (pigging) of the TWW line to remove internal build‑up and ensure unrestricted flow prior to installing and commissioning the new diffuser.
Outcome
Works were completed safely, efficiently, and without incident.
The new TWW diffuser system delivered improved wastewater dispersion performance, exceeding the client’s requirements. Indianic’s ability to adapt to unforeseen subsea conditions, combined with technical expertise and disciplined commercial diving practices, ensured a successful outcome.
Comprehensive photographic records and inspection data were provided, giving Red Rock confidence in the long‑term integrity and performance of the upgraded diffuser system.
