Guidance for 2011 Reporting of the Concentration in Tailings and Waste Rock (TWR) to the NPRI
Based on the information received in 2009, EC has developed a simplified reporting format to be entered in the Comment Field. The reporters must report average concentration and qualifying information about the detection limit for the measured samples. The simplified minimum reporting requirements are described below.
(1) For consistency and convenience of data comparison, the reporters must report the average concentration in parts per million (ppm). If necessary, they should convert the reportable concentration units that are expressed in terms of percentage (%), mg/kg (for solids), or mg/L (for liquids) into ppm
- 0.0001% = 1 ppm, or 1.0% = 10,000 ppm
- 1 mg/kg = 1 ppm
- 1 mg/L = 1 ppm
(2) For the detection limit information, the reporter should indicate whether the average concentration data value is based on one of the following situations:
- No samples below the detection limit
- Less than 50% of the samples below the detection limit
- More than 50% of the samples below the detection limit
- All samples below the detection limit
Note: A value of half of the detection limit should be used to calculate average concentration when the analytical measurement value of the sample is below the detection limit. If all measurements are below the detection limit, then the average concentration can be reported as 0.
The reporters can provide additional information on concentration in the Comment Field.
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