Wastewater surveillance

A range of surveillance measures are in place to rapidly detect COVID-19 in the community. This includes wastewater surveillance.

Detection of COVID-19 fragments informs public health authorities about the geographical locations that require an increase in clinical testing.

The detection of viral fragments in wastewater can also come from someone who has recovered from COVID-19 and while no longer infectious can shed fragments of the virus.

Wastewater sampling catchment sites

Wastewater samples will be routinely collected in the below areas.

Population numbers in each catchment are below 50,000 which is in line with the requirements to capture the accurate detection of COVID-19 cases.

Greater Darwin sampling catchment sites

  • Ludmilla Sewage Treatment Plant (STP) inlet
  • Stuart Highway Darwin CBD
  • Mindil Beach
  • Leanyer/Sanderson STPs #1 – inlet from Western Area
  • Leanyer/Sanderson STPs #2 – inlet from Northern Suburbs
  • Rocklands Drive Tiwi, isolated to RDH campus
  • Palmerston Sewage Treatment Plant inlet
  • Bridle/Catalina Road intersection
  • Stow Road pump station – isolated to Howard Springs Quarantine Facility

Additional samples may also be collected from portable toilet facilities following major events where large numbers of participants are visitors from interstate.

One sample site will be located at the Stow Road pump station in Howard Springs which receives wastewater exclusively from the Howard Springs Quarantine Facility (HSQF).

This sampling site is expected to return a positive result when active cases are residing at HQSF.

Alice Springs sampling catchment sites

  • MH45 Quarantine Facility
  • 29A CBD & Gillen
  • 24A CBD & Northern
  • WWMF/A11

How samples are collected

NT Health is undertaking wastewater sampling program with assistance from the Power and Water Corporation (PWC) and Darwin-based company Trop Water.

The program comprises of passive sampling of sewage, at sites prior to treatment, to extract COVID-19 RNA to determine the presence/absence of the virus in particular geographic locations and give an indication of concentrations in sewage.

Samplers are inserted into sewers at pre-determined locations and are left in the flow of wastewater for a 24 hour period.

They are then collected and placed into a sealed bag and put on ice for consignment/delivery to the South Australia testing facility.

If a positive sample is detected

Any positive detection in wastewater samples will be assessed by NT Health.

Further investigations may be undertaken, including immediate resampling if there any doubts about the source of the virus fragments.

If there are known positive cases in the catchment area where a positive sample is identified, this will be taken into consideration during the investigation.

A confirmed positive wastewater test result is particularly important if there are no known recent positive COVID-19 cases in that area.

Public health advice will be issued where action is required by the community.

This might include messaging to people in the area to get tested, particularly if they have symptoms of COVID-19 and also might include providing additional testing locations in the area.

Last updated: 10 August 2022

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Last updated: 10 August 2022