Water sampling
Chemical analysis of water is an exacting procedure. The use of extremely sophisticated instruments and procedures means that some elements can be detected to amazingly low concentrations. Only a few years ago this level of detection was not available, and consequently the standards set for water quality determination are always changing. Data collection and analysis involves a chain of responsibilities, and the data will only be as good as the weakest link in the chain. The accurate collection of data is the first and most important link in this chain. It is essential that contamination of the sample does not occur during sample collection, or at any other time. To ensure that accuracy and precision goals are met the following precautions are taken:
- water is collected upstream of the person sampling, from a specified position in the flow
- latex gloves are worn to prevent chemicals that are naturally present on the skin, or from deposits left on hands from other activities, from washing into the sample bottle; for example, cigarette smoking leaves a cyanide deposit on smoker's hands and this level of contamination can easily be detected by modern analytical equipment
- chemical stability of sample water is maintained by specific preservatives, e.g., nitric acid is used in samples collected for metal ion analysis
- the sampling procedure includes the use of controls, blanks and replicate samples for quality control
samples are quickly chilled to slow down reactions that could change the nature of the sample in the time between sample collection and analysis - samples are sent by courier, immediately after collection, to independent laboratories for analysis
- all procedures are carefully documented, including the 'chain of custody', in accordance with Martha Mine's quality assurance programme; Australian/New Zealand Standard procedures are followed at every step of the sample collection and handling process (as outlined in AS/NZS 5667.1-6: 1998).
above: The ground and surface water monitoring network. Note the monitoring points upstream and downstream of the treated water discharge points.
1. Martha Mine. 2. Conveyor route. 3. Processing Plant and Water Treatment Plant. 4. Tailings Storage Facility 2. 5. Black Hill. 6. Ohinemuri River. 7. Union Hill.
above: Regular sampling is undertaken at the water treatment plant. This is the only part of the site where protective hardhats are not required to be worn.
above: Groundwater bore sampling on the waste rock embankment. Latex gloves help prevent contamination of samples.
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