Guidance for reporting tailings and waste rock: chapter 5
Questions and answers
- A facility has identified a number of NPRI substances that meet the tailings and waste rock reporting requirements for 2006. Would this listing be applicable in every reporting year between 2006 and 2009?
The substances that are required to be reported for tailings and waste rock is based on the calculation of the mass reporting threshold for manufactured, processed, or otherwise used manufactured, processed, or otherwise used (MPO) for each individual reporting year. It is expected that due to the large quantities of tailings and waste rock, the same substances would meet the threshold determination for each reporting year. It should be noted that the number of speciated Polycyclic Aromatic Hydrocarbons (PAHs) for NPRI reporting has increased from 20 in 2006 to 29 for 2009. The 2006 to 2008 notice requires reporting on the 29 PAHs, and therefore you may need to report on additional PAHs for 2006 and 2007.
What is overburden? Are the substances in overburden required to be reported to the NPRI?
Overburden is the unconsolidated materials that exist between the top soil and ore or bitumen deposit. The substances contained within this material are excluded from the reporting threshold calculations and as a result reporting to the NPRI.
A metal mine uses cyanide-compounds in a gold leaching operation to extract gold from ore. Cyanide that would otherwise be lost during the liberation of cyanide from the gold-cyanide complexes is able to be recovered from the tailings, and re-used to leach more gold from the ore pile. How should the facility consider these cyanides for threshold determination, and how should they be reported for the disposal at the tailings management area?
The cyanides should be considered towards all MPO activities for the mass threshold determination. This is because the cyanides are used to react with the gold in the ore in the first place, and they are manufactured as the gold cyanide, and are then processed as a reactant since the gold from the compound is distributed into commerce. The cyanides should be reported as the net quantity disposed at the tailings management area, regardless of the number of recovery process for the flotation agent (cyanides) in the tailings circuit that has taken place.
What industrial sectors could be required to report tailings or waste rock in 2009, but not for 2006 to 2008?
For 2009, sectors that could be required to report for mine waste include, but are not limited to the following: (1) aluminum smelters could have the tailings containing “red mud” deposited on site in the tailings management area for the required reporting, (2) the Lime Manufacturing Sector could be required to report the substances in the limestone as part of the waste rock management located on the same site, (3) pits and quarries.
For potash and limestone mines, are trace metals and other substances that are found in natural earth/rock reportable to the NPRI?
The main components that are found in potash mines and limestone are salts of sodium, magnesium, potassium and calcium chlorides and sulphates. These specific substances are not found on the NPRI substance list. However, trace metals or other NPRI substance would be reportable if the applicable thresholds are met, subject to the exclusions.
Should strong acids that are neutralized prior to their disposal be reported to the NPRI as disposals in tailings and waste rock management areas?
Acids that are neutralized prior to being disposed of in tailings and waste rock management areas should not be reported as being disposed to tailings and/or waste rock. Please note that the use of any acid listed on the NPRI must be considered when calculating whether applicable NPRI thresholds are met.
How should a facility report on an annual “net quantity” to the NPRI?
Consideration of the "net quantity" of NPRI substances being disposed on-site refers to the "reprocessing of materials" in a given reporting year. For this exercise, you do not need to account for the internal movement of waste rock material if it is completed in the same type of management area. However, you need to consider the quantities of “additions” and “removals” accordingly if the material is moved from waste rock management area to tailings management area or vice versa. The “net quantity” that should be reported to the NPRI is the final amount of NPRI substances that either added or removed at the end of the applicable calendar year. For some facilities, their net quantity will be a positive value and for other facilities it will be a negative value.
Are decommissioned mines subjected to the NPRI tailing and waste rock reporting requirements?
Decommissioned mines are normally expected to comply with the good practice of mine reclamation. Any NPRI substances that are associated with reclamation activities must be considered toward threshold and reporting calculation since the activities are no different than the management of "tailings" and "waste rock".
A mine has accumulated waste rock that meets the exclusion criteria set out in the notices over a number of years. It now wants to use some of this material to build a road on site and to then sell some of the remaining material as construction aggregate. It will have to crush and screen material for these uses. Does it have to consider this activity in its reporting threshold and how is this to be reported to the NPRI?
The crushing and screening of the material is not one of the criteria for determining whether the waste rock is to be reported. This activity would not affect the exclusions applicable to this waste rock. However, the facility will have to consider the amount of particulate matter generated in the threshold for reporting and may have to report emissions of Total Particulate matter (TPM), Particulate matter less than or equal to 10 microns (PM10) or Particulate matter of a size less than or equal to 2.5 microns (PM2.5). The threshold for reporting substances in Part 4 of Schedule 1 of the annual NPRI notices is based on releases to air.
A mine has accumulated a quantity of waste rock over a number of years, and reported the amount of lead and mercury sent to waste rock management areas under the 2006 to 2008 notice for mine waste reporting. The material is now (for 2009) being moved to another location on site. How does this affect reporting?
If the material is being sent from one waste rock management area to another waste rock management area on site, then no new reporting is required.
How are we to report on PAHs when we do not know the amount of individual species?
When there is no information on the species, report the PAHs under: “PAHs, total unspeciated” If you have information on species from some processes, but not others, report the releases, disposals and transfers of the species for those processes where this information is available. Report for the other processes under “PAHs, total unspeciated”. See section 4.6 of the reporting guide.
I use tailings to fill in stopes or as pillars to provide support for the surrounding rock in an underground mine. How do I report this?
In this situation, the tailings material containing NPRI substances are used as part of the structure of the facility. As a result, the general exclusion for structural components of the facility applies.The NPRI substances found in the tailings used for underground fill are not reported. However, the net disposal of NPRI substances to the tailings management area are reported. If the quantity of NPRI substances in fill removed from the tailings management area(s) exceeds the amount sent to the tailings management area(s) in any given year, a negative quantity (net withdrawal from tailings management area) is to be reported.
Coal mining operations produce coarse and fine rejects as a result of the separation of rock from coal washing operations. Should these rejects be reported as waste rock or as tailings to the NPRI?
For the purposes of reporting to the NPRI, materials separated from coal are considered tailings whether they are coarse rejects or fines. These materials cannot be considered waste rock since they are processed and removed from the coal to be transferred into a tailings management area. By definition, waste rock is not processed in any way except to remove it and store it at another location.
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