\\na.aecomnet.com\lfs\apac\christchurch-nzchc1\legacy\projects\605x\60544823\6. draft docs\6.1 reports\waihi north\app d - kinetic and column testing\appendix d - attachment a.docx 5 of 6 6.0 Ongoing Column Sample Collection During this period the leachate should initially be monitored weekly. Depending on the results, the monitoring frequency may be extended with time. During monitoring, it is recommended that the leachate tubing is removed carefully from the bucket or fastening point to the column. Leachate should be collected directly from the tubing into laboratory supplied containers suitable for the analysis of the parameters detailed in Table 2. Once all containers are full, leachate should be collected directly into a clean beaker. Field parameters should be collected utilising a calibrated multi-parameter (or similar individual meters) and the following field parameters should be recorded: • pH • Conductivity • Temperature The remaining leachate should be left to drain into the bucket until the tubing runs dry (except in the case of the fully saturated column – refer to comment below). The volume of leachate within the bucket should be recorded and disposed of before reconnecting the tubing to the empty bucket. In the event that insufficient leachate drains from the tubing and base of column to enable sample collection and the accurate measurement of field parameters, static water within the bucket should be utilised. If no leachate water (or insufficient leachate water) is available, a measured volume of 500 mL of deionised water should be poured into the columns at the top, and the leachate should be collected as described above. The fully saturated column should be replenished with de-ionised water so that the waste rock remains fully saturated. The water level of the columns and buckets should be monitoring during and after heavy rainfall events in order to prevent overflow. Samples collected should be stored cold and sent for laboratory analysis for the following parameters. Table 2. Recommended analytical suite for column sample collection pH Conductivity Acidity (mgCaCO3/L) Alkalinity (mgCaCO3/L) Sulphate Total Organic Carbon (TOC) Dissolved Aluminium Dissolved Iron Dissolved Calcium Dissolved Magnesium Dissolved Sodium Dissolved Potassium Dissolved Antimony Dissolved Arsenic Dissolved Barium Dissolved Cadmium Dissolved Cobalt Dissolved Chromium Dissolved Copper Dissolved Lead
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