Planning for the future:Mandorah Jetty and boat ramp

May 2017

The Mandorah Jetty and boat ramp are key infrastructure facilities servicing the Mandorah, Wagait Beach and Belyuen communities, and visitors to the area from Darwin and surrounds.

Passenger ferry travel to and from the Mandorah jetty is the quickest way to get across the harbour between Darwin and the Cox Peninsula area.

The jetty is now more than 40 years old and the cost of maintaining this aging asset is increasing.The jetty and boat ramp have been upgraded many times, and maintenance costs are increasing. The exposed location means it is impacted by storms, cyclonic weather and tides.

The Northern Territory Government recognises the importance of this asset to the local community and has undertaken a planning study to assess the safety and suitability of the jetty and boat ramp for the current and future needs of the community.

The Northern Territory Government engaged Jacobs consulting engineers to assess the current condition of the jetty and boat ramp and provide recommendations for long term options for upgrade or replacement. This included a community consultation component to gather feedback from key stakeholders, community members, and the ferry operators and users. This study considered various options to upgrade the existing facilities and plans for new facilities. A summary of options is provided overleaf.

Design Options

Build new facilities approximately 500m north of the existing jetty including a new ferry pontoon, gangway, new roll on/roll off boat ramp and a groyne to form a harbour. In addition, this may require a new access road and car park. The current indicative order of cost for this option is $49 million.

Relocation of the boat ramp only to a new location at Woods Inlet - 5km south of the exsiting jetty.

This option is not recommended because it does not provide any upgrade to the Mandorah Jetty or ferry service infrastructure and will require costly dredging works and other landside facilities.

Mandorah

Darwin

Cullen Bay

Woods Point

OPT

ION

3

OPT

ION

4

Add a floating ferry pontoon and gangway to the existing jetty structure with a continuous offshore breakwater structure. Also upgrade the existing boat ramp by resurfacing and levelling. Current indicative order of cost for this option is $66 million. Not recommended. Offshore breakwater is more costly to build and existing boat ramp cannot be used as a roll on/roll off facility

Add a floating ferry pontoon and gangway to the existing jetty structure with a discontinuous offshore breakwater structure. Also, upgrade the existing boat ramp by resurfacing and levelling. Current indicative order of cost for this option is $84 million. Also not recommended because offshore breakwater is more costly to build and the existing boat ramp cannot be used as a roll on/roll off facility.

OPT

ION

1A

OPT

ION

1B

What happens next?

Build new facilities close to the existing jetty including new ferry pontoon, gangway, rock groyne and new roll on/roll off boat ramps. The land based groyne structure will provide protection from wind and waves to the new facilities. The existing jetty could be reserved for use as a recreational facility. The current indicative order of cost for this option is $24 million. The study found this option provides the best value for money and will provide new upgraded infrastructure for commercial, commuter and recreational use.

This is the preferred option based on the community consultation and the planning study.

OPT

ION

2

The Department of Infrastructure, Planning and Logistics will carry out further engineering work to confirm the cost estimates and solution details with a focus on the design solutions for the preferred option.For further information please contact projects.tipd@nt.gov.au or contact Stakeholder Engagement ManagerCasey Lovelock on 8924 7118.

Not recommended because it doesn’t use the recently built landslide facilities, and the required work will have an undesirable visual impact on the Mandorah coastline. This option is also likely to incur higher ongoing maintenance costs than other options and would likely require regular dredging.