WA’S Covid-19 wastewater surveillance program is being expanded to include metropolitan sub-catchment sites with the City of Wanneroo recently added to the program.
Most of the City of Wanneroo lies within the sewage catchment area of the Beenyup wastewater treatment plant.
Yesterday a Department of Health (DoT) spokesman told Yanchep News Online that seven sub catchments of the Beenyup catchment area have now been added to the wastewater surveillance program and that the City of Wanneroo lies within one of those seven sub catchment areas.
The expanded Western Australian SARS-CoV-2 (Covid-19) wastewater surveillance program will include 24 metropolitan sub-catchment sites.
Prior to the addition of sub-catchment sites weekly wastewater sampling was undertaken at six metropolitan wastewater treatment plants, 12 regional sites across 10 regional localities and 10 remote border towns.
The Alkimos wastewater treatment plant (which treats wastewater from about 80,000 people) and the Beenyup wastewater treatment plant in Craigie (which treats wastewater from about 660,000 people) are two of the six metropolitan plants sampled weekly.
In May 2020 Water Corporation head of water quality Rachael Miller said in the Shire of Gingin the Water Corporation only treated wastewater from Ledge Point, Lancelin and Seabird.
Yanchep News Online asked DoH if there were there any circumstances under which the wastewater surveillance program would extend to include sampling water from the Ledge Point, Lancelin and Seabird treatment plants.
“Sites included in the wastewater surveillance program are constantly being reviewed to ensure they inform the public health response,’’ the DoT spokesman said.
“Where a need to commence wastewater testing is identified, additional sites may be included.’’
A study involving CSIRO lead author Dr Warish Ahmed published in March last year said wastewater monitoring could help identify hotspots and target localised public health responses, such as increased individual testing, setting up fever clinics and the provision of health warnings.
“Wastewater surveillance affords the possibility of detecting cases that are still pre-symptomatic or asymptomatic in the progression of SARS-CoV-2 infection,’’ the study said.
“However, the speed of the public health response is critical to break the chain of transmission through case identification and isolation.
“For this reason, it is critical that wastewater sample collection and testing be performed in a timely manner and results reported to public health decision makers within hours to days.
“In addition to being timely, wastewater testing must also be sensitive to minimize the probability of false negatives.’’
But the study said wastewater surveillance might need to move beyond wastewater treatment plant influent and into the catchment to achieve adequate population-level coverage.
Many areas of WA including old Yanchep and much of the Shire of Gingin rely on septic tanks.
Last year the State Health Incident Coordination Centre said people who work and live in areas solely serviced by septic tank systems would not be captured by the state’s wastewater treatment plant testing program.
