Goorambat

2012/13: Goorambat Gross Alpha Activity 0.69 (Bq/L)

The maximum gross alpha activity result at Goorambat unexpectedly exceeded the ADWG screening level of >0.5 Bq/L which was suspected an anomalous result and prompted further investigation in accordance with ADWG 2011. The initial retest for gross alpha and gross beta activity at Goorambat returned lower levels (<0.28 Bq/L respectively) which were in the normal test range. In accordance with North East Water’s risk management plan and risk-based monitoring program, testing for radiological parameters (including individual radionuclides) is now scheduled quarterly for Goorambat until levels can be verified. (North East Water 2012/13).

Radionuclides (Other beta- and gamma-emitting)

GUIDELINE
No specific guideline values are set for beta- or gamma-emitting radionuclides.
Specific beta- or gamma-emitting radionuclides should be identified and determined only
if gross beta radioactivity (after subtracting the contribution of potassium-40) exceeds 0.5 Bq/L (27.6 Bq of beta activity per gram of stable potassium).

GENERAL DESCRIPTION

Several radionuclides that are classified as beta-particle or gamma-ray emitters may occasionally be present in drinking water. The significant long-lived nuclides in this group are the naturally occurring isotopes potassium-40, lead-210 and radium-228, and artificial radionuclides caesium-137 and strontium-90. Tritium, another nuclide in this group, is present in the environment both from natural sources and as a result of nuclear fall-out and nuclear power generation.

Levels of strontium-90 and caesium-137 in the Australian environment have decreased substantially since atmospheric testing of nuclear weapons ceased, and these radionuclides are not detectable in drinking water. In the absence of a nuclear power industry in Australia, these nuclides are likely to be present in significant concentrations in drinking water only as a result of transient contamination following an event such as a nuclear accident.

Potassium‑40 occurs naturally in a fixed ratio to stable potassium. Potassium is an essential element for humans, and is absorbed mainly from ingested food. Potassium-40 does not accumulate in the body but is maintained at a constant level independent of intake. The average concentration of potassium in an adult male is about 2 g/kg of bodyweight, which gives an activity mass concentration of potassium-40 of 60 Bq per kg of bodyweight. The corresponding value for females is slightly less.

Lead-210, like radium-226, is a decay product of the uranium-238 series. Food is the most important route by which lead-210 enters the human body, and the annual intake depends on diet: highest concentrations are found in fish and other aquatic species. Generally, lead-210 concentrations in drinking water are considerably less than concentrations of either radium-226 or radium-228.

TYPICAL VALUES IN AUSTRALIAN DRINKING WATER
Concentrations of potassium-40 in Australian drinking water supplies vary widely, from below 0.05 Bq/L in surface water sources to more that 1 Bq/L in some supplies drawn from groundwater.
There are only limited data on concentrations of other beta- or gamma-emitting radionuclides such as lead-210, strontium-90 and caesium-137 in Australian drinking water supplies. Lead-210 concentrations are probably below 0.05 Bq/L and concentrations of artificial radionuclides are negligible.

20/1/23 – Goorambat (Victoria) – E.coli

20/1/23: Goorambat. E. coli detection (148 orgs/100 mL). A section 18 and section 22 notification was made to DH following an E. coli detection (148 orgs/100 mL) which occurred in
the Goorambat reticulation as part of routine monitoring. The sample was collected by the external laboratory on 19 January 2023 and the result was reported to North East Water on 20 January 2023. The same sample had a chlorine residual of 0.01 mg/L, turbidity of 3.63 NTU and coliform result of >250 orgs/100 mL. The CWS tanks that supply the reticulation upstream of
the detection site were tested by the external laboratory on the same day and had no E. coli, with other parameters within normal operating ranges.

The corporation completed an investigation which confirmed the detection was not representative of the water delivered, and was deemed a false positive. In accordance with the Guidelines for Investigating and Reporting E. coli Detections, an investigation report was submitted to DH. DH reviewed the investigation findings and made an assessment requiring North East Water to submit a section 18 for non-compliance with the E. coli water quality standard. This was due to the low chlorine result in the sample and inability to confirm that the chlorine barrier was effective. A section 18 was therefore submitted on 18 September 2023.

“Coliforms are Gram-negative, non-spore-forming, rod-shaped bacteria that are capable of aerobic and facultative anaerobic growth in the presence of bile salts or other surface active agents with similar growth-inhibiting properties. They are found in large numbers in the faeces of humans and other warm-blooded animals, but many species also occur in the environment.

Thermotolerant coliforms are a sub-group of coliforms that are able to grow at 44.5 ± 0.2°C. E. coli is the most common thermotolerant coliform present in faeces and is regarded as the most specific indicator of recent faecal contamination because generally it is not capable of growth in the environment. In contrast, some other thermotolerant coliforms (including strains of Klebsiella, Citrobacter and Enterobacter) are able to grow in the environment and their presence is not necessarily related to faecal contamination. While tests for thermotolerant coliforms can be simpler than for E. coli, E. coli is considered a superior indicator for detecting faecal contamination…” ADWG 2011