Larrakeyah Outfall Closure Plan

Power and Water Corporation (PWC) briefed the NT Government this week about its plans to close the Larrakeyah Outfall.

The Corporation’s wastewater discharge licence for Larrakeyah Outfall was renewed by the Department of Natural Resources, Environment and the Arts in October 2006. The licence requires PWC to undertake works to redirect sewage flows to an alternate facility and closure of the outfall by October 2011.

Power and Water has allocated $35 million over the next four years to upgrade
Darwin’s sewerage system as part of an $814 million investment in infrastructure announced by Power and Water earlier this year.

In parallel with the Larrakeyah outfall closure program, Power and Water is
developing a Darwin Region Sewerage Strategy over the next two years covering the remaining five treatment plants and outfalls.

Paul Heaton, General Manager, Water Services Power and Water said

“There are a number of issues with the diversion of the Larrakeyah Outfall and
discussions have begun with residents and the Darwin City Council about alternative routes and a detailed survey of these alternatives is currently being undertaken.

“It is likely that construction activity associated with the diversion will be required through the CBD and at this point, will include a pump station and rising main, a bored tunnel or some combination of both.

“While CBD diversion works will commence in 2009, completion of the total program and physical diversion of sewage flows are not expected to be complete until 2010 or 2011, after upgrades to the Ludmilla Wastewater Treatment Plant and East Point Outfall are completed.”

Milestones for the $35 million program include:

• Investigation of diversion issues that may arise from the geological profile along the proposed route (e.g. hard rock, old tunnels); this has already started and should be completed by early 2008.

• Pipeline design and procurement process to be undertaken during 2008.

• A construction tender target date set for November 2008.

• Construction to commence in early 2009 with completion planned for mid year 2009.

• Hydrodynamic modelling of an extension to the East Point Outfall has already started and will continue until late 2008.

• Design of the East Point extension will commence in late 2008 with an expected completion of mid 2009.

• Construction of the East Point Outfall extension to start in early 2010.

Separate to the $35 million program, approximately $15 million worth of works has already been undertaken. To date, this includes a new trunk sewer in Mitchell Street, a new trunk sewer at Dinah Beach along Tiger Brennan Drive and a new sewage pumping station at Dinah Beach. In addition to these a new sewage rising main from Dinah Beach to Parap; upgrades to the Frances Bay sewage pumping station; upgrades to the Parap trunk sewer; and upgrades to the various facilities at LWWTP have been completed.

Works to the value of $1 million are currently underway at the Frances Bay sewage pumping station to install a new switchboard and pumps and the LWWTP to control odour and provide new effluent pumps.

Map attached – high res version available on request

Works Completed to Date ($15m)
1.		A new trunk sewer in Mitchell Street;
2.		A new trunk sewer at Dinah Beach along Tiger Brennan Drive;
3.		A new sewage pumping station at Dinah Beach;
4.		A new sewage rising main from Dinah Beach to Parap;
5.		Upgrades to the Frances Bay sewage pumping station;
6.		Upgrades to the Parap trunk sewer; and
7.		Upgrades to the various facilities at Ludmilla Wastewater Treatment Plant (LWWTP).
Outstanding Works ($35m)
8.		Diversion works to deliver sewage from the Larrakeyah catchment to the Dinah Beach trunk sewer;
9.		Further upgrades to the LWWTP;
10.		Duplication of the East Point effluent rising main;
11.		Extension of the East Point outfall.

Contact:
Judie Brennan
Media Manager,
Corporate Communications
Power and Water Corporation
0401 117 599 or 8985 8481