North Marine was contracted to install 13 new tidal gauge boards, inspect, brace & clean 17 existing boards and verify Australian Height Datum (AHD) to within +/- 25mm accuracy.

About the Location

Adjacent to Cairns Trinity Inlet, East Trinity Reserve has a dense, environmentally sensitive habitat, unstable terrain and limited access.

Straddling both the Wet Tropics World Heritage Area and the Great Barrier Reef World Heritage Area, the location is one of the world’s most successful acid-sulphate soil remediation projects and is a significant Mandingalbay Yidinji Indigenous Protected Area.

Scope of Work

The following works ensured that all required locations at East Trinity have a robust, easy-to-read and stable (flow velocity, salt water, acid, and UV) gauge board, that is accurately tied to the Australian Height Datum:

• Installation of 13 gauge boards as per the scope of works
• Replacement of 9 broken or damaged gauge board piles
• Cleaned and reset 8 existing gauge board piles
• Verification of 1 Iron Bridge gauge board affixed to the bridge – found to be out by 240mm
• In addition to the works in the original contract, DES also requested 5 new locations be braced due to high tidal flow or debris concerns for the area. The additional bracing works were completed as a variation on the original contract.

North Marine crew used a combined shore and vessel-based methodology for the logistically complex and high-risk works.

The new piles were driven into various terrain types with machinery custom-modified for the task. Existing pile gauges were replaced, cleaned and/or strengthened as necessary.

Laser-cut gauge board markers were supplied by DES, and all other installation materials and equipment were supplied by North Marine.

North Marine subcontracted a specialist Bathymetric Surveyor to verify Australian Height Datum targets.

Key risks included the presence of crocodiles in the waterways where the gauge boards were located, changing conditions associated with the tidal nature of the site, the presence of soft geotechnically unstable sediments in the drains and creeks, and weather systems affecting the works.

Planning & Methodology Considerations

• Operating within the highly environmentally sensitive habitat of East Trinity Reserve in Queensland
• Risk management – Control measures for hazards such as crocodiles, snakes, marine flora and fauna, unstable terrain and dense vegetation
  Substantial tidal conditions
• Access restrictions: North Marine worked with DES and Traditional Owners to clear access routes into areas of the reserve

North Marine Discriminators:

1. Comprehensive ‘Environmental Management Procedures’ when operating in rivers, harbours and areas of high environmental sensitivity – with extensive experience in such operations
2. Adept at delivering logistically complex & remote projects
3. A fleet of suitable charter vessels and machinery to perform works
4. North Wharf, our marine base, is located less than 1km from the entrance to the East Trinity Wetland
5. Excellent working relationships with Stakeholders
6. Local SME marine business in North Queensland, with a local workforce
7. Extensive track record as both a Government and a Private Sector contractor
8. Ethically and socially aware
9. Approved ‘Crocodile Management Plan’
10. Hold required work permits
11. Experienced Management and Key Personnel
12. ISO Accredited