Moore Street – Ravenshoe (Queensland) – E.coli
DWI-7-498-00078 – 04 JANUARY 2017 – RAVENSHOE WSS – MOORE STREET NONCOMFORMANCE
On 04 January 2017, operational monitoring was undertaken within the Ravenshoe water supply scheme from Moore Street. The turbidity was increased due to the recent rainfall within the area resulting in a concentration of 4.79 NTU. An additional sample was collected from Moore St for monthly verification testing. On 05 January 2017, internal analysis of the samples did not detect any E coli. On 06 January 2017, TRC received a notification from the Cairns Water Laboratory indicating an E coli concentration of (estimated) 1 CFU/100ml within the Moore St sample.
Corrective and Preventative Action: On 16 January 2017, TRC had determined turbidity and chlorine levels had stabilized. TRC commenced internal processes in accordance with the DWQMP to close out the incident. This included undertaking three consecutive internal and two external NATA accredited E coli samples. On 20 January 2017, it was determined all five samples were clear for E coli.
On 27 January 2017, the boil water notice was lifted across all schemes via social media. TRC have undertaken reviews of internal notification processes and mitigation techniques (e.g. contingency plans) during high rainfall events. Due to the lack of filtration within these schemes, the event cannot be entirely prevented. However TRC continually work towards improving internal response towards these events and community engagement…
DWI-7-498-00079/80/81 – 06 JANUARY 2017 – MILLSTREAM, CASSOWARY AND BELLVIEW WSS EVENT
This event was triggered by the investigation undertaken on the 04 January 2017 and described above. On 06 January 2017, TRC received a notification from the Cairns Water Laboratory indicating an E coli concentration of (estimated) 1 CFU/100ml within the Moore St sample. Follow up sampling was undertaken and it was identified that the Ravenshoe, Cassowary, Bellview, and Millstream schemes were experiencing a sudden increase in turbidity and decrease in chlorine. After correspondence with DEWS representatives, TRC commenced the process of implementing boil water notices across the three schemes in addition to Ravenshoe as a precautionary measure.
Tablelands Regional Council Annual Drinking Water Quality Management Plan 2016-17
“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