Potable water on mine sitesMines safety bulletin no. 178 | 07 February 2019 | Version 1
Potable water is defined in the Australian Drinking Water Guidelines (ADWG) as ‘water that, based on current knowledge, is safe to drink over a lifetime, that is, it constitutes no significant risk to health’. These guidelines include health and aesthetic (taste and appearance) parameters.
Under the Coal Mining Safety and Health Regulation (part 12, section 87 (1)), coal mine site senior executives (SSEs) are required to provide sufficient potable water to cater for the needs of the largest number of workers who may be employed at the mine in a single shift.
A brief interpretation of the legal obligations in health legislation is that the manufacturer and supplier of a substance (in this case water) must not cause harm if used correctly and as intended.
What mine sites need to do?
It’s important that all coal mines, including exploration and construction sites, maintain a scheduled routine drinking water testing program. These schedules should be outlined in the site water quality risk management plan (WQRMP) with the aim of ensuring drinking water is safe to consume and protecting the source of water from potential contamination. This is particularly important on sites operating their own water treatment plants to supply potable water to coal mine workers.
SSEs must undertake (or review) risk assessments specific to potable water on mining leases, to identify potential hazards, (microbiological, chemical and physical), and assess the effectiveness of existing controls. This information should be used to develop part of a site’s Safety and Health Management System (SHMS) covering potable water, the goal being to have a WQRMP supported by robust data to validate a high confidence (>95%) in water quality as defined by the ADWG.
The risk management process should also consider the source of the water supply; design of the supply network; water treatment processes; water storage facilities on site; inspection and maintenance of water storage and supply networks; water quality monitoring arrangements; and risk communication to the workforce.
It is strongly recommended that a person with specialist expertise (e.g. microbiologist, environmental scientist or water quality specialist) and a broad area of expertise and understanding across all disciplines and stakeholders, be involved in this process.
For sites with a Water Treatment Plant (WTP):
- Use industry recognised certified water plant operators (Cert III).
- Consider water piping network designs that prevent back feed of raw water into the potable water system through inadvertent operation of valves etc.
- Develop an inspection regime to monitor effective functionality of all aspects of the WTP.
- Consider the feed source of the water and potential for contamination.
Where potable water is supplied to site (e.g. water tanker), ensure the drinking water service provider is registered with a current drinking water quality management plan. Review this quality management plan to assess the on-going effectiveness of preventative controls.
For the storage of potable water on site, ensure storage tanks, filters and water system materials are suitable for long term storage and distribution without introducing contaminants.
- Develop and implement a risk based drinking water quality monitoring program
- conduct verification assessments within the distribution system and at the point of supply
- determine sampling locations and frequencies by risk assessment, covering access points across the whole of mine, including remote storage, crib rooms, CHPP, workshops, draglines, ice machines etc.
- consider additional assessments for short term storage tanks used during shutdown and construction.
- Monitoring priorities should focus on health risks. Where aesthetic characteristics are unacceptable, further investigation may be necessary to identify the cause and improve the palatability of the water.
- Maintain a record of test results to evaluate system performance and identify emerging trends.
- Consider independent third party sample collection and monitoring of water quality across site.
Examples of generic key characteristics for verifying drinking water quality assessments are shown in Table 1 below. Specific key characteristics may differ between sites depending on the outcomes of the risk assessment.
Table 1 – Examples of key characteristics
|E. Coli (a thermotolerant coliform)||Faecal bacteria contamination indicator (note E.coli are short lived outside of the gut)|
|Thermotolerant Coliforms||Faecal bacteria contamination indicators that are long lived and resilient outside of the gut|
|Heterotrophic plate count|
Marked increases, measured in orders of magnitude, provide evidence of deteriorating conditions that should be investigated.
|Total Coliforms||Detect a wider range of microorganisms and are generally considered a better indicator of distribution system integrity and cleanliness.|
|Total Dissolved Solids (TDS)||Guide for good palatability|
|Turbidity||Performance of media filtration systems|
|Electrical Conductivity||Can be used as a surrogate for TDS|
|Metals||Ground / surface water source contaminants|
|Disinfection by-products||Character selection dependant on the water treatment process adopted|
|Hardness||Add calcium carbonate to minimise undesirable build-up of scale in pipework.|
|Colour||True colour units based on aesthetic considerations|
|pH||Acidity or alkalinity of water|
Additional information including the guidelines for specific characteristics is provided in ADWG Part V: Factsheets.
Compare monitoring results to the guideline values in the ADWG. Develop a response process (e.g. trigger action response plan (TARP)), detailing measured and controlled actions in response to elevated results. Such actions may include:
- repeat testing
- additional water treatment or dosing
- immediate isolation of potable water access points (if required)
- provision of alternate potable water supplies
- communication protocols for any actions to the workforce.
In the event of interruption to potable water supply it is important to:
- ensure adequate and independent secondary supply (e.g. bottled water or arrangements for onsite delivery by tanker) is readily available should the primary supply be deemed non-potable
- ensure alternate arrangements for critical safety devices such as eye wash stations are in place, should an interruption to the supply of potable water occur.
Communicating health risk
It is important that coal mine workers have a basic understanding of factors that may potentially affect the quality of their drinking water, including both the health and aesthetic factors. It is recommended that mines provide general awareness training to coal mine workers that covers but is not limited to:
- factors that may impact the quality of drinking water
- distinguish between health and aesthetic factors
- the mines water quality monitoring program
- basic understanding of results
- site TARP process
- communication protocols for elevated result.
Good health risk communication with the workforce is important. This may prevent situations where sites are managing OUTRAGE rather than an actual health risk. This can be time consuming and result in unnecessary concern / panic among the workforce.
Authorised by Luca Rocchi - Chief Inspector of Mines
Contact: Fritz Djukic, Inspector of Mines, +61 7 4999 8504 Fritz.Djukic@dnrme.qld.gov.au
Issued by the Queensland Department of Natural Resources, Mines and Energy