Guide for reporting to National Pollutant Release Inventory 2001: step 2

Step 2: estimate releases and transfers and collect the information required for the NPRI report

The second step is to estimate your releases and transfers and collect the information required to complete the National Pollutant Release Inventory (NPRI) report. This section outlines different methods and sources of information available to assist you in estimating releases and transfers of NPRI substances for which you are required to report.

Note that the reporting criteria for Parts 1 and 2 NPRI substances is "manufacture, process or otherwise use". However, it is the quantity of releases and transfers of the substance that must be reported to the NPRI.

The 2001 Canada Gazette notice states that the information required by the NPRI need only be reported to the Minister of the Environment if the facility owner or operator possesses the information or may reasonably be expected to have access to the information. Consequently, the NPRI does not require additional monitoring or measurement of the quantities or concentration of substances released to the environment, beyond those already required under the provisions of other laws or regulations. You are, however, required to show "due diligence" in obtaining the information required by the 2001 Canada Gazette notice.

Sources of information

Technical guides

The References and bibliography section contains a list of technical guidance documents that can be consulted for technical information on certain substances or processes. This includes technical guides prepared by Environment Canada, the U.S. Environmental Protection Agency (EPA) and industry associations.

In 2001, Environment Canada published a technical guide to assist facilities in the wood-preservation sector estimate their releases of certain substances. The document, Guidance for Wood-Preservation Facilities Reporting to the National Pollutant Release Inventory (April 2001), provides a step-by-step methodology for estimating releases and transfers of NPRI substances from wood-preservation facilities, including polycyclic aromatic hydrocarbons (PAHs), dioxins/furans and hexachlorobenzene (HCB). The guide is available on the NPRI reporting software CD and is posted on the NPRI Web site.

Material safety data sheet (MSDS)

A Material safety data sheet (MSDS) is an important source of information on the composition of a purchased product. Suppliers of hazardous materials are required, as part of the Workplace Hazardous Materials Information System (WHMIS), to supply MSDSs on request.

NPRI emission factor database

Environment Canada has compiled emission factors for substances listed with alternate thresholds in the NPRI (Parts 2, 3 and 4 substances). The majority of emission factors are from the U.S. EPA's "Factor Information Retrieval (FIRE) data system" database, however there are some included from other sources. The database is further explained in Appendix 11.

The database is available on the NPRI reporting software CD or can be downloaded from the NPRI Web site.

Permits and certificates of approval

Another source of information on substances at your facility may be any municipal, provincial, territorial or regional operating permits and certificates of approval you have obtained.

Method detection limit

There are several situations in which the issue of measurements below the detection limit, or method detection limit (MDL), arises in NPRI reporting. The MDL is the smallest concentration of the substance under analysis (analyte) that produces an instrumental response and that meets all analyte detection and identification criteria of a specified test method.

Facilities must use reasonable judgment as to the presence and amount of an NPRI-listed substance based on the best readily-available information. An indication that a reportable substance is below the MDL is not equivalent to stating that the substance is not present. If it is known that the substance is present, a concentration equivalent to half of the MDL should be used. Persons at a facility should not estimate releases solely on measurement or monitoring devices; they should also rely on their knowledge of specific conditions at the site.

Where, during the year, multiple measurements of a substance in a given process stream are below the MDL, and the facility has no other reason to believe that the substance is present, the facility should assume that the concentration of the substance in that process stream is zero.

Where, over a year, multiple measurements are taken and some indicate that the substance is above and some are below the MDL, the facility has good reason to assume that the substance is present. The facility should, therefore, use a concentration value of half the MDL for those measurements where the concentration was below the MDL.

Retain information collected

Persons reporting to the NPRI for 2001 are required to retain copies of all information upon which their report was based, at the facility or parent company in Canada, for three years. Refer to Step 7 for details.

Methods of estimation

Estimates of the quantity of a substance that was manufactured, processed or otherwise used, and the quantity that was released on site or transferred off site, may be based on one of the following methods, listed in declining order of expected accuracy:

  • monitoring or direct measurements
  • mass balance calculations
  • emission factors, or
  • engineering estimates

When you report on-site releases to each environmental medium and off-site transfers for disposal or recycling, you will enter a "basis of estimate" code in the NPRI reporting software. Details of the methods of estimation and codes are provided in Step 5; examples are provided in Appendices 5 and appendix6.

Schedule 1, Part 1, substances

If the reporting criteria are met for an NPRI Part 1 substance, then all on-site releases and off-site transfers for that substance must be reported regardless of the concentration or quantity (including "zero" releases and transfers).

Examples of estimating releases and transfers are provided in Appendix 5; "basis of estimates" codes are explainded in Step 5.

Schedule 1, Part 2, substance - mercury (and its compounds)

If the reporting criteria are met for mercury (and its compounds), then all on-site releases and off-site transfers of mercury (and its compounds) must be reported regardless of the concentration or amount. The facility is required to submit a substance report even if on-site releases or off-site transfers are zero. You must account for total releases of mercury (and its compounds) from your facility to each environmental medium (air, water, land and underground injection).

Examples of estimating releases and transfers of mercury (and its compounds) are provided in Examples 2 and example3 of Appendix 6; "basis of estimate" codes are explained in Step 5.

Schedule 1, Part 3, substances - polycyclic aromatic hydrocarbons (PAHs)

With the exception of the activity of wood preservation using creosote, if your facility met the 50-kg reporting threshold for the 17 PAHs, you must report on-site releases and off-site transfers individually for each of the 17 PAHs that were incidentally manufactured and released or transferred.

A facility used for wood preservation must submit a report for each/any of the 17 individual PAHs released on site or transferred off site from a wood-preservation process using creosote, regardless of the quantity of PAHs released or transferred or the number of hours worked by employees. All PAHs released on site or transferred off site from wood-preservation processes using creosote must be reported, regardless of the quantity.

If you do not have information available to estimate releases and transfers for any of the 17 individual PAHs, the PAHs may be reported together under the listing "PAHs, total Schedule 1, Part 3". You may report for the 17 individual PAHs, or "PAHs, total Schedule 1, Part 3", but not both. If you report under the listing of "PAHs, total Schedule 1, Part 3", indicate in the "Comments" field which substances are included in the data, if known.

You must account for total releases of the 17 PAHs from your facility to each environmental medium (air, water, land and underground injection) and transfers off site for disposal or recycling.

An example of estimating releases and transfers of PAHs is provided in Example 2 of Appendix 6; "basis of estimate" codes are explained in Step 5.

Schedule 1, Part 4, substances - dioxins/furans and hexachlorobenzene (PAH)

A facility that met the criteria set out in Step 1 must provide substance reports for dioxins/furans and PAH. However, what you report for releases and transfers may differ from a typical NPRI substance report. The dioxins/furans or PAH substance report submitted to the NPRI will indicate, for on-site releases to each environmental medium and for each off-site transfer activity:

  • the quantity released on site or transferred off site as the result of incidental manufacture during an activity listed in Tables 6 or table7
  • the quantity released on site or transferred off site resulting from wood preservation using pentachlorophenol
  • that directly-measured releases to a specific medium or transfers off site were at concentrations above, equal to or below the level of quantification (LoQ) concentrations set out in Table 10 (this option is available only if estimates were based on direct measurements)
  • that there were no releases to a specific medium or no transfers off site, or
  • that no information was available on which to base an estimate.

The use of "basis of estimate" and "detail" codes for Part 4 substances is explained below.

Determine whether you must report quantities released on site to each environmental medium and transferred off site. You must report quantities released on site and transferred off site unless:

  • you directly measure dioxins/furans and PAH resulting from incidental manufacture from an activity listed in Tables 6 or table7, and the concentrations are below the LoQ values as defined below, or
  • you have no information available on which to base estimates of on-site releases and off-site transfers

Use the flowchart in Figure 6 to determine what you must report to the NPRI for dioxins/furans and PAH. Read the flowchart for on-site releases to each environmental medium (that is, air, water, land and underground injection) and for each type of off-site transfer. You must account for total releases of dioxins/furans and PAH from your facility to each environmental medium.

Figure 6: What you must report for dioxins/furans and PAH

Decisional flow diagram regarding what you must report for dioxins/furans and PAH

With the exception of facilities used for wood preservation using pentachlorophenol, a facility should only consider quantities of dioxins/furans or HCB that were incidentally manufactured as the result of the activities listed in Tables 6 or table7. Wood-preservation facilities using pentachlorophenol must consider all sources of releases or transfers of dioxins/furans or HCB arising from the use of pentachlorophenol for the purpose of wood preservation.

What are toxic equivalents (TEQs) of dioxins/furans?

You must report on-site releases and off-site transfers of dioxins/furans in units of grams TEQ of the 17 congeners listed in Table 5. Dioxins and furans are often found in complex mixtures, typically at extremely low concentrations, making it difficult to determine the cumulative toxicity of the mixture. Accordingly, scientists have assigned toxic equivalency factors (TEFs) to each dioxin/furan congener as weighting factors. These TEFs are assigned relative to the toxicity of 2,3,7,8-TCDD, the most toxic congener, which is assigned a TEF of 1.

To apply and compare TEQs, the values must be calculated using the same set of TEFs. Most release data on dioxins/furans currently available in Canada are in units of international TEQs (North Atlantic Treaty Organization/Committee on the Challenges of Modern Society, NATO/CCMS, 1989). More recent work undertaken for the World Health Organization (van den Berg, 1998) has resulted in a revised set of TEFs, not just for humans, but for mammals, fish and birds. However, since most of the emission factors currently available are in international TEQs, the TEF values listed in Table 8, must be used for reporting to the NPRI.

To calculate the TEQ of a mixture, you must first multiply the concentration of an individual congener by its respective TEF, or weighting factor, to obtain the congener-specific TEQ concentration. The sum of the TEQ concentrations for the individual congeners is the TEQ concentration for the mixture.

Table 8a: toxic equivalency factor (TEF) values for dioxins
CAS Number Congener Abbreviation TEF
1746-01-6 2,3,7,8-Tetrachlorodibenzo-p-dioxin 2,3,7,8-TCDD 1
40321-76-4 1,2,3,7,8-Pentachlorodibenzo-p-dioxin 1,2,3,7,8-PeCDD 0.5
39227-28-6 1,2,3,4,7,8-Hexachlorodibenzo-p-dioxin 1,2,3,4,7,8-HxCDD 0.1
57653-85-7 1,2,3,6,7,8-Hexachlorodibenzo-p-dioxin 1,2,3,6,7,8-HxCDD 0.1
19408-74-3 1,2,3,7,8,9-Hexachlorodibenzo-p-dioxin 1,2,3,7,8,9-HxCDD 0.1
35822-46-9 1,2,3,4,6,7,8-Heptachlorodibenzo-p-dioxin 1,2,3,4,6,7,8-HpCDD 0.01
3268-87-9 Octachlorodibenzo-p-dioxin OCDD 0.001
Table 8b: toxic equivalency factor (TEF) values for furans
CAS No. Congener Abbreviation TEF
51207-31-9 2,3,7,8-Tetrachlorodibenzofuran 2,3,7,8-TCDF 0.1
57117-31-4 2,3,4,7,8-Pentachlorodibenzofuran 2,3,4,7,8-PeCDF 0.5
57117-41-6 1,2,3,7,8-Pentachlorodibenzofuran 1,2,3,7,8-PeCDF 0.05
70648-26-9 1,2,3,4,7,8-Hexachlorodibenzofuran 1,2,3,4,7,8-HxCDF 0.1
72918-21-9 1,2,3,7,8,9-Hexachlorodibenzofuran 1,2,3,7,8,9-HxCDF 0.1
57117-44-9 1,2,3,6,7,8-Hexachlorodibenzofuran 1,2,3,6,7,8-HxCDF 0.1
60851-34-5 2,3,4,6,7,8-Hexachlorodibenzofuran 2,3,4,6,7,8-HxCDF 0.1
67562-39-4 1,2,3,4,6,7,8-Heptachlorodibenzofuran 1,2,3,4,6,7,8-HpCDF 0.01
55673-89-7 1,2,3,4,7,8,9-Heptachlorodibenzofuran 1,2,3,4,7,8,9-HpCDF 0.01
39001-02-0 Octachlorodibenzofuran OCDF 0.001

(NATO/CCMS, 1989)

Example of a TEQ calculation

The following table shows the different concentrations of four dioxin and furan congeners in an ash sample. If these concentrations were simply summed together, the sample would be reported as containing 80 nanograms (ng) of dioxins/furans in each kilogram (kg) of ash. However, 1,2,3,4,7,8-HxCDF is 10 times less toxic than 2,3,7,8-TCDD. By applying the TEFs to each congener and summing the values, the resulting toxic equivalent (TEQ) for the mixture is 25 ng TEQ of dioxins/furans in each kg of ash, or 25 ng TEQ/kg.

Dioxins/furans Sample concentration congener
(ng/kg)
Toxic equivalency factor
(TEF)
Toxic equivalent
(ng TEQ/kg ash)
2,3,7,8-TCDD 10 1 10
1,2,3,7,8-PeCDD 20 0.5 10
1,2,3,4,7,8-HxCDF 30 0.1 3
1,2,3,6,7,8-HxCDF 20 0.1 2
Total concentration - -
25 ng TEQ/kg

Methods of estimation

"Basis of estimate" codes

When you report on-site releases to each environmental medium and off-site transfers for disposal or recycling, you will enter a "basis of estimate" code in the NPRI reporting software. There are four methods of estimating releases, listed in declining order of expected accuracy:

  • monitoring or direct measurement (Code M)
  • mass balance (Code C)
  • emission factors (Code E)
  • engineering estimates (Code O)

Selecting Code "NA" (not applicable) as the "basis of estimate" indicates that there were no releases from your facility to this medium, or no transfers off site.

In instances when no information is available, use the "basis of estimate" code "NI" when reporting dioxins/furans and HCB . Enter "NI" as your "basis of estimate" code if your facility met reporting criteria for dioxins/furans or HCB, but you have no information available on which to base an estimate of the quantity released or transferred.

"Detail" codes

For dioxins/furans and HCB substance reports only, a "detail" code field is available in the NPRI reporting software adjacent to the "basis of estimate" field. There are three "detail" codes:

  • concentrations at or above LoQ (Code AL)
  • concentrations below LoQ (no quantity entered) (Code BL), and
  • concentrations below LoQ (enter a quantity) (Code BQ).

These "detail" codes only apply to data from monitoring or direct measurements (Code "M" in the "basis of estimate" field). If you enter the "AL" detail code, you must enter the quantities released or transferred. If your concentrations are below LoQ, then reporting of quantities released or transferred is optional - you must select one of two detail codes. If you enter the "BL" detail code for concentrations below LoQ, you have chosen not to report the quantities released or transferred. If you enter the other detail code for concentrations below LoQ (Code "BQ"), you have chosen to report the quantities released or transferred.

The use of "basis of estimate" and "detail" codes is explained in the following sections and summarized in Table 9.

Table 9: how to report releases and transfers of dioxins/furans and HCB
Basis of estimate code Detail code Quantity field
Monitoring or direct measurement (Code M) At or above LoQ (Code AL) you must enter quantity released or transferred
Monitoring or direct measurement (Code M) Below LoQ (no quantity entered) (Code BL) n/a
Monitoring or direct measurement (Code M) Below LoQ (quantity entered) (Code BQ) you must enter quantity released or transferred
Mass balance (Code C) n/a you must enter quantity released or transferred
Emission factors (Code E) n/a you must enter quantity released or transferred
Engineering estimate (Code O) n/a you must enter quantity released or transferred
No information available (Code NI) n/a n/a
Not applicable (Code NA) n/a n/a

Direct measurements

A direct measurement is based on measured concentrations of the substance in a waste stream and the volume/flow rate of that stream. Direct measurements should be made of on-site releases and off-site transfers representative of the facility's normal operating conditions or production levels.

If your facility has made direct measurements of dioxins/furans or HCB, then you should use these data to determine which releases and transfers, if any, you must report to the NPRI. Enter Code "M" in the "basis of estimate" field in the NPRI reporting software. Examples of how to estimate releases using measured data are provided in Appendix 6.

The following sections will help you determine if your measured concentrations are above, equal to or below the LoQ for each type of material that you release on site and transfer off site.

Level of quantification (LoQ)

The level of quantification is defined in Section 65.1 of the Canadian Environmental Protection Act, 1999 (CEPA), as "the lowest concentration that can be accurately measured using sensitive but routine sampling and analytical methods". Environment Canada determines LoQ values by carrying out statistical analyses of several sets of measurements from a variety of emission sources. The LoQ is calculated as 10 times the standard deviation of replicated measurements. The standard deviation is the variability of the test data associated with the sampling, analysis and actual source emission changes during testing, using standard test methods (Environment Canada, 1989).

Table 10 provides estimated LoQs for dioxins/furans and HCB for three types of material or waste streams that may be released on site or transferred off site - gaseous, liquid and solid. The LoQ values listed include both final and draft values published by Environment Canada. You must compare your measured concentrations to the appropriate LoQ for each type of on-site release and off-site transfer that you report to the NPRI. Containment in an off-site landfill is an example of a type of off-site transfer for disposal. Recovery of pollution-abatement residues is an example of a type of off-site transfer for recycling.

Environment Canada has published estimated LoQ values for dioxin/furan and HCB concentrations in gaseous releases (Environment Canada, 1999). You should use these values to determine whether concentrations in releases to air from stacks and other sources are above, equal to or below the LoQ.

Table 10: estimated LoQ values for concentrations of dioxins/furans and HCB
State of material Estimated LoQ for concentrations of dioxins/furans Estimated LoQ for concentrations of HCB
Gaseous 32 pg TEQ/m3 6 ng/m3
Liquid 20 pg TEQ/L 70 ng/L
Solid 9 pg TEQ/g 2 ng/g

Environment Canada has not published an LoQ for dioxin/furan concentrations in liquids, but has extrapolated a draft LoQ for dioxins/furans in liquids from the effective LoQ for 2,3,7,8-TCDD in the Pulp and Paper Mill Effluent Chlorinated Dioxins and Furans Regulations. Facilities should use 20 pg TEQ/L as the LoQ for concentrations of dioxins/furans in liquids.

Environment Canada has developed an estimated LoQ for concentrations of HCB in chlorinated solvents. Facilities should use 70 ng/L as the estimated LoQ for concentrations of HCB in all liquids.

Environment Canada published proposed LoQ values for dioxins/furans and HCB in soil in early 2000 (Environment Canada, 2000). You should use LoQ values of 9 pg TEQ/g for dioxins/furans and 2 pg/g for HCB to determine whether concentrations of dioxins/furans or HCB in solid materials are equal to or above the LoQ. Incinerator bottom ash, pollution-abatement residues and sludges are examples of solid materials containing dioxins/furans or HCB that may be released on site or transferred off site.

Are your measured concentrations equal to or above LoQ?

When comparing measured concentrations to LoQ values, measurements should be made of on-site releases and off-site transfers representative of your facility's normal operating conditions or production levels. If you determine that your measured concentrations are equal to or above the LoQ, then you must estimate and report the quantities of on-site releases and off-site transfers for the 2001 calendar year using these concentrations. Enter Code "AL" (At or above LoQ) in the "Detail" code field in the NPRI reporting software.

Are your measured concentrations below LoQ?

When comparing measured concentrations to LoQ values, measurements should be made of on-site releases and off-site transfers representative of your facility's normal operating conditions or production levels. If you directly measure dioxins/furans and HCB in an on-site release or off-site transfer resulting from incidental manufacture from an activity listed in Tables 6 or 7, and the concentrations are below LoQ, reporting the quantities released on site and transferred off site is optional. You must select one of two Detail codes. If you enter Code "BL" for concentrations below LoQ, you are not required to enter the quantities released or transferred. If you enter Code "BQ" for concentrations below LoQ, you have chosen to report the quantities released or transferred.

Example

A facility has directly measured dioxins/furans resulting from incineration of non-hazardous solid waste (incidental manufacture of dioxins/furans from an activity listed in Table 6). The facility determined that dioxins/furans were released to air from a stack at a concentration of 20 pg TEQ/m³. The measured concentration is below the LoQ of 32 pg TEQ/m³, so the facility does not need to report the quantities of dioxins/furans released on site from stacks. The facility will report that releases to air of dioxins/furans from the stack are below LoQ (Detail code "BL").

Dealing with multiple data points and non-detected values

If you have several sets of directly-measured concentrations for a given release or transfer, you should compare the average or mean value of all the concentrations with the appropriate LoQ. The method detection limit (MDL) is the smallest concentration of the substance under analysis (analyte) that produces an instrumental response and that meets all analyte detection and identification criteria of a specified test method. If some of the concentration data are below the MDL (that is, they are non-detected), you should use a value of one-half the MDL to calculate the mean concentration for comparison with the LoQ and to calculate the quantities of dioxins/furans and HCB released on site or transferred off site.

Emission factors

An emission factor is based on average measured emissions from several similar processes. Emission factors usually express releases as a ratio of quantity released to process or equipment throughput. In the absence of data from direct measurements, your facility should estimate on-site releases or off-site transfers of dioxins/furans or HCB as a result of incidental manufacture, using emission factors that you possess or to which you have reasonable access. Enter Code "E" in the "basis of estimate" field in the NPRI reporting software.

Emission factors may be developed for one or more facilities using measured data under similar process conditions. Environment Canada compiled many emission factors for activities in Tables 6 and table7 in the emission factor database for alternate-threshold substances (see Appendix 11). You should indicate, in the "comments" field of the NPRI reporting software, the source of any emission factor used. If Environment Canada has included an emission factor for your activity in the emission factor database for alternate-threshold substances, but you choose not to use it, you should provide your reason in the "comments" field.

If you use emission factors to estimate on-site releases and off-site transfers, you must report the quantities released or transferred. You cannot report that your concentrations for a specific on-site release or off-site transfer are below the LoQ.

No information available

If information is not available for releases to a specific medium or for an off-site transfer, either through direct measurements, emission factors or some other source to which the facility possesses or may reasonably be expected to have access, then the facility should report "no information available" for on-site releases to that medium or for that type of off-site transfer. Enter Code "NI" in the "basis of estimate" field in the NPRI reporting software. If you report "no information available" for an activity for which Environment Canada has included an emission factor in the emission factor database for alternate-threshold substances, you should provide your reason for not using the values in the emission factor database in the "comments" field of the NPRI reporting software.

No on-site releases to a specific medium or transfers off site

If there are no dioxins/furans or HCB released on site to a given medium or transferred off site from the facility for the specified activity, the facility should report "not applicable" for that medium or transfer category for that substance. Enter Code "NA" in the "basis of estimate" field in the NPRI reporting software, indicating that there were no releases to the given medium or transfers off site for that category.

For example, if dioxins/furans were only released to air from a combustion process of an activity listed in Tables 6 or table7, and there was no related process with releases to water as a result of that activity, the facility reports "not applicable" for on-site releases of dioxins/furans to water. Similarly, if there were no off-site transfers of material from the activity that generates the dioxins/furans, report "not applicable" for each off-site transfer category.

You now have completed Step 2 and should be ready to install the NPRI reporting software. Proceed to Step 3.

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