Date: 9/2/2015
Estimated duration of incident: Less than 2 days
Location of incident: Longwood
Nature of incident: One detection of E.Coli (1 organism per 100ml in the Clear Water Storage (CWS) and 2 organisms per 100ml in the reticulation system) in routine samples on 9/Feb/2015.
Drinking water supplies potentially effected: Longwood
Action taken in response:
Full investigation of the treatment process was carried out and storages were assessed for possible ingress. New temporarily installed tanks at Longwood WTP for receiving tankered water were found to be unsealed. Those tanks were then isolated. Sampling at the treatment plant and distribution system for E.Coli was undertaken. The secondary tank located before town (Tubbs Hill CWS) was dosed with chlorine to boost chlorine residual into town. The town distribution system was flushed and resampling was carried out. Retesting of the water supply did not detect any E.Coli.
Communication with customers: Boiled water notices and SMS notifications were prepared for distribution pending lab results. These notices were not issued as the lab results came clear. A boil water advisory was not needed in instance.
DHHS notification: A Section 22 notification was sent to the Department of Health & Human Services on 10/2/2015.
Date: 15/12/2014
Estimated duration of incident: 2 – 3 months
Location of incident: Creighton Creek – Longwood
Nature of incident:
In December 2014, a bushfire occurred at Creighton Creek – Longwood which falls within the catchment area for drinking water supply at Longwood. A lightning started the fire and burnt approximately 6500 hectares of land. Bushfires in water reservoir catchments is known to initiate water quality issues. Potential impacts include the following:
* Soil erosion in catchment due to loss of vegetation
* Elevated turbidity, colour and organic materials in raw water source
* Decrease in dissolved oxygen in reservoir as a result of increased oxygen demand exerted by organic matters
* Increased chlorine demand due to increase in organic matters
* Higher water quality risk following a rainfall event as a result of surface run off, transporting contaminants into the water supply
Most of the expected issues did eventuate with actual impacts as follows:
* Water quality in the Nine Miles Reservoir which supplies the Longwood water treatment plant (WTP) was impacted by the event. The intense fire burnt the vegetation surrounding the reservoir. Windy conditions carried silt and ashes mostly from the gully upstream of the reservoir into the water supply
There were elevated turbidity, colour and organic materials in raw water supply to Longwood WTP. The treatment plant was able to cope with the increased levels
* Significant increase in E.Coli numbers in the raw water. It was observed there was a number of dead stock upstream of the reservoir. They were most likely the source of E.Coli following a rainfall event in Jan 2015
* Release of metals (manganese and iron) from the bottom of the reservoir a month following the bushfire. This event is most likely attributed by the increase in decomposing organic matters which exerted oxygen demand in the sediment layer
Drinking water supplies potentially affected: Longwood
Action taken in response: The following actions were taken in response to the incident:
* Notified Department of Health and Human Services and formed a Contingency Plan Working Group for incident management
*Surveyed the catchment at fortnightly intervals and reservoir at weekly intervals to assess the condition and risk
* Buried dead stock to reduce microbial risks
* Increased sampling frequency at raw water intake into the treatment plant for risk indicators
* Tankered water for supply when E.Coli numbers in raw water were detected to be of elevated risk
* Artificial aeration of Nine Mile Reservoir to supress metals release
* Potassium permanganate dosing implemented for manganese control
* Maintained and monitored plant performance before it was returned to service in Feb 2015.
Communication with customers: Media releases for notification of tankering
DHHS notification: Yes
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
Longwood (Victoria) – Chloroacetic Acids
2007/8; Longwood (Victoria) Trichloroacetic Acid 0.200mg/L (Highest Detection)
2007/8: Longwood (Victoria) Dichloroacetic Acid 0.110mg/L (Highest Detection)
Australian Guidelines Trichloroacetic Acid 0.100mg/L, Dichloroacetic Acid 0.100mg/L
“Chloroacetic acids are produced in drinking water as by-products of the reaction between chlorine and naturally occurring humic and fulvic acids. Concentrations reported overseas range up to 0.16mg/L and are typically about half the chloroform concentration. The chloroacetic acids are used commercially as reagents or intermediates in the preparation of a wide variety of chemicals. Monochloroacetic acid can be used as a pre-emergent herbicide, dichloroacetic acid as an ingredient in some pharmaceutical products, and trichloroacetic acid as a herbicide, soil sterilant and antiseptic.” Australian Drinking Water Guidelines – National Health and Medical Research Council…
There are no epidemiological studies of TCA carcinogenicity in humans. Most of the human health data for chlorinated acetic acids concern components of complex mixtures of water disinfectant by-products. These complex mixtures of disinfectant by-products have been associated with increased potential for bladder, rectal, and colon cancer in humans [reviewed by Boorman et al. (1999); Mills et al. (1998)].” Ref: tmp/Trichloroacetic acid (TCA) CASRN 76-03-9 IRIS US EPA.htm
Longwood (Victoria) – Chloral Hydrate
Longwood 0.022mg/L Chloral Hydrate 2011/12 (Highest Detection)
Longwood 0.024mg/L Chloral Hydrate 2010/11(Highest Detection)
Longwood 38ug/L Chloral Hydrate 2009/10 (Highest Detection)
2004 Australian Drinking Water Guideline: Trichloroacetaldehyde (chloral hydrate): 0.02mg/L
2011 Australian Drinking Water Guideline: Trichloroacetaldehyde (chloral hydrate): 0.1mg/L
“Chloral hydrate is a disinfection by-product, arising from chlorination of water containing naturally occurring organic material (NOM). Chloral hydrate has only been detected by Goulburn Valley Water since changing to a new contract testing laboratory in November 2007. The Department of Health is currently conducting a study into the detection of chloral hydrate across Victoria.”