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Supplementary Guide for Reporting to the National Pollutant Release Inventory - Alternate Thresholds 2000

Section 7: Examples of How to Estimate Releases

This chapter provides examples of how to estimate releases using monitoring data and emission factors (Examples 1-6), adapted from the draft US EPA Guidance for Reporting Toxic Chemicals within the Dioxin and Dioxin-like Compounds Category, and examples of various reporting scenarios for alternate-threshold substances (Examples 7-9). With the exception of wood-preservation processes, PAHs, dioxins/furans and HCB are typically by-products formed during certain manufacturing and combustion processes, and as such the quantities released as a result of incidental manufacture cannot be determined using engineering calculations or a mass balance. Instead, direct measurements or emission factors must be used. Environment Canada has prepared a database with emission factors for all alternate-threshold substances, called the NPRI Emission Factor Database for Alternate-Threshold Substances (see Appendix 9).

7.1 Estimating Releases Using Direct Measurements

This section provides examples of how to calculate releases of dioxins/furans to air, water and land using direct measurements.

Example 1: Calculating Air Releases of Dioxins/Furans Using Stack Monitoring Data

Stack testing has determined that dioxins/furans were detected in the stack gases at your facility at a concentration of 10-9 g TEQ per dry standard cubic metre of gas (10 ng TEQ/dry m3). The moisture content in the stack was typically 10%. The stack gas velocity was typically 8.0 m/s. The diameter of the stack is 0.3 m. Calculate the annual air release of dioxins/furans from the stack of your facility.

Step 1. Calculate volumetric flow of stack gas stream. Calculate volumetric flow of stack gas stream.

Step 2. Correct volumetric flow for moisture content in stack gas stream.

Stack gases may contain large amounts of water vapour. The concentration of the chemical in the exhaust is often presented on a 'dry gas' basis. For an accurate release rate, you must correct the stack or vent gas flow rate in Step 1 for the moisture content in your facility's stack gas. This is done as follows:

Correct volumetric flow for moisture content in stack gas stream.

Step 3. Estimate annual stack emissions to air.

Multiply the dry gas volumetric flow rate by the concentration of dioxins/furans measured in the stack gases.

Estimate annual stack emissions to air

Note: If this facility met all of the NPRI reporting criteria for dioxins/furans, on-site releases of dioxins/furans to air would be reported to the NPRI in the following manner. The measured concentration of dioxins/furans was 10 ng TEQ/m3 (10 000 pg TEQ/m3), which is greater than the LoQ for dioxins/furans in a gaseous medium of 32 pg TEQ/m3. The substance report for dioxins/furans releases to air would indicate: Basis of Estimate Code - Monitoring or direct measurement (Code M); Detail Code - At or above LoQ (Code AL); Quantity - 0.13 g TEQ.

Example 2: Calculating Water Releases of Dioxins/Furans Using Monitoring Data

Your facility is subject to a provincial certificate of approval for the discharge of dioxins/furans into surface waters. You are required to conduct periodic monitoring of the effluent discharge from your facility. In this example, quarterly samples of effluent were taken and analyzed for the content of dioxins/furans. Each sample was an hourly, flow rate-based composite taken for one day to be representative of the discharge for that day. The total effluent volume for that day was also recorded. Your facility operated 350 days in the year. The following data were collected on each sample day.

Quarter Sample No.Discharge Flow Rate
(106 L/Day)
Dioxins/Furans Concentration
(pg TEQ/L)
18025
28025
316025
440025

Determine if you are required to report for this facility and, if so, calculate the quantity of dioxins/furans released from this facility.

To calculate the amount of dioxins/furans discharged on each sample day, the concentration of dioxins/furans in the discharge is multiplied by the discharge flow rate for that day, as shown below for the first-quarter sample.

Step 1. Calculate the amount of dioxins/furans discharged per day from each day of sampling.

Daily discharge of dioxins/furans
   = (daily effluent flow rate) × (dioxins/furans concentration in effluent)

From the table above, the calculation of daily dioxins/furans effluent discharge for the first sampling quarter is:

The calculation of daily dioxins/furans effluent discharge

Step 2. Find the average quantity of dioxins/furans discharged in the effluent per day.

Using the same equation, the second-, third- and fourth-quarter dioxins/furans monitoring events are calculated to be 0.002 g TEQ/day, 0.004 g TEQ/day and 0.01 g TEQ/day, respectively. Then the average daily dioxins/furans discharge rate for all monitoring events at this facility was:

The calculation of the average quantity of dioxins/furans discharged

Step 3. Calculate the annual discharge of dioxins/furans to surface waters.

The facility operated 350 days in the year. The estimated annual discharge of dioxins/furans to the surface water is calculated as follows

Calculation of the annual discharge of dioxins/furans to surface waters

Note: If this facility met all NPRI reporting criteria for dioxins/furans, on-site releases of dioxins/furans to water would be reported to the NPRI in the following manner. The measured concentration was 25 pg TEQ/L, which exceeds the LoQ for dioxins/furans in a liquid of 20 pg TEQ/L. The substance report for dioxins/furans released to water would indicate: Basis of Estimate Code - Monitoring or direct measurement (Code M); Detail Code - At or above LoQ (Code AL); Quantity - 1.575 g TEQ.

Example 3: Estimating Releases On Site to Land in the Disposal of Sludge

Under the NPRI, the disposal of NPRI-listed substances in on-site landfills is considered a release to land. The disposal of NPRI-listed substances in an off-site landfill is considered an off-site transfer for disposal.

Your facility generated approximately 1 kg of dry sludge per 4000 L of wastewater treated at the facility's on-site industrial wastewater treatment plant. The facility operations produce approximately 100 million litres of wastewater per day. The facility operated 350 days in the year. Monitoring indicated that the sludge, on average, contained approximately 3 ng TEQ dioxins/furans per kg dry sludge produced. All sludge from your facility was placed in an on-site landfill. What was the annual amount of dioxins/furans released to land from your facility as a function of land disposal of the sludge contaminated with dioxins/furans?

Step 1. Determine the amount of sludge produced per day from the wastewater treatment process.

Determine the amount of sludge produced per day

Step 2. Determine the amount of dioxins/furans contained in the sludge produced each day.

Average daily dioxins/furans loading in sludge
   = (total sludge generated) × (average dioxins/furans concentration in sludge)

Average daily dioxins/furans loading in sludge

Step 3. Calculate the annual release of dioxins/furans to land based on annual days of operation per year.

Annual release of dioxins/furans to land
    = (average daily dioxins/furans loading in sludge) × (total operating days per year)

Calculation of the annual release of dioxins/furans to land

Note: If this facility met all NPRI reporting criteria for dioxins/furans, on-site releases of dioxins/furans to land would be reported to the NPRI in the following manner. The measured concentration of dioxins/furans was 3 ng TEQ/kg (or 3 pg TEQ/g), which is less than the LoQ for dioxins/furans in a solid medium of 9 pg TEQ/g. However, this facility has chosen to report the quantity of dioxins/furans released on site to land. The substance report for dioxins/furans released to land would indicate: Basis of Estimate Code - Monitoring or direct measurement (Code M); Detail Code - Below LoQ (Code BQ); Quantity - 0.026 g TEQ. The quantity reported is rounded to the nearest thousandth (i.e., 0.026 g TEQ), since the smallest unit that the NPRI reporting software will accept for dioxins/furans is 0.001 g TEQ


7.2 Estimating Releases Using Emission Factors

Facilities may either develop their own facility-specific emission factors or use the emission factors provided by the NPRI to estimate annual releases and transfers of various substances. The following examples show how to calculate annual releases of dioxins/furans using either chosen emission factors or the emission factors compiled by Environment Canada (see Appendix 9). In either case, the procedures are the same.

If a facility develops its own emission factor for any alternate-threshold substance, it should indicate this in the "Comments" field when completing the NPRI report.

The units vary according to the units of measure of activity level, but usually are weight per unit weight of production, or weight per unit volume of production. Common units for dioxin/furan emission factors for various processes are:

  • combustion processes - nanograms TEQ of dioxins/furans per kilogram of material combusted, processed or produced
  • point-source effluent discharges into surface waters - picograms TEQ of dioxins/furans per litre of wastewater discharged, and
  • waste generated that will be disposed - picograms TEQ of dioxins/furans per kilogram of waste or sludge generated.

Example 4: Estimating Air Releases of Dioxins/Furans from Stack Emissions

Dioxins/furans were released to air from an incineration unit. The emission factor that best fits your facility is 10 ng TEQ of dioxins/furans released from the stack per kilogram of materials processed. Each day your facility processed 25 000 kg of materials, and operated 350 days in the year. The emission factor is appropriate for your level of dioxins/furans control. Estimate the annual release of dioxins/furans from the stack of your facility.

Step 1: Calculate the annual release of dioxins/furans to air.

Estimating Air Releases of Dioxins/Furans from Stack Emissions

Note: If this facility met all NPRI reporting criteria for dioxins/furans, on-site releases of dioxins/furans to air would be reported to the NPRI in the following manner. The substance report for dioxins/furans released to air would indicate: Basis of Estimate Code - Emission factors (Code E); Detail Code - not applicable; Quantity - 0.088 g TEQ. The quantity reported is rounded to the nearest thousandth (i.e., 0.088 g TEQ), since the smallest unit that the NPRI reporting software will accept for dioxins/furans is 0.001 g TEQ

Example 5: Estimating Water Releases of Dioxins/Furans to Surface Water

Your facility discharged 400 million litres per day of treated wastewater into surface water. The emission factor you have found to be most appropriate for your facility is 10 pg TEQ dioxins/furans per litre of wastewater discharged. The emission factor reflects the level of dioxins/furans control that is occurring at your facility. Your facility operated 365 days in the year. Estimate the annual release of dioxins/furans to surface water.

Step 1: Calculate the annual release of dioxins/furans to water.

Estimating Water Releases of Dioxins/Furans to Surface Water

Note: If this facility met all NPRI reporting criteria for dioxins/furans, on-site releases of dioxins/furans to water would be reported to the NPRI in the following manner. The substance report for dioxins/furans released to water would indicate: Basis of Estimate Code - Emission factors (Code E); Detail Code - not applicable; Quantity - 1.46 g TEQ.

Example 6: Estimating Releases of Dioxins/Furans to Land from a Wastewater Treatment Plant

In Example 5, the wastewater treatment plant process generated 1 kg of dry sludge per 5000 L of wastewater treated. The wastewater treatment process removed 50% of the dioxins/furans from the wastewater prior to discharging wastewater into surface water. All of the sludge generated at your facility was placed in an on-site landfill. Calculate how much dioxins/furans were released to land at your facility.

Step 1. Determine the amount of sludge generated each day at your facility.

Sludge generated = (sludge generation rate/L wastewater) × (wastewater throughput)

Estimating Releases of Dioxins/Furans to Land from a Wastewater Treatment Plant

Step 2. Estimate the emission factor for dioxins/furans in the sludge.

Assuming that all the dioxins/furans removed from the wastewater during the treatment process are contained in the sludge generated from the wastewater treatment process, the emission factor for sludge can be calculated as a function of dioxins/furans removal efficiency from the wastewater. Thus, the emission factor for dioxins/furans in wastewater multiplied by the removal efficiency gives an approximate indication of the dioxins/furans emission factor for sludge at your facility. In the following calculation, assume the density of sludge is 500 g/L.

Estimate the emission factor for dioxins/furans in the sludge

Step 3. Calculate the annual release of dioxins/furans to land.

Calculation the annual release of dioxins/furans to land

Note: If this facility met all NPRI reporting criteria for dioxins/furans, on-site releases of dioxins/furans to land would be reported to the NPRI in the following manner. The substance report for dioxins/furans released to land would indicate: Basis of Estimate Code - Emission factors (Code E); Detail Code - not applicable; Quantity - 0.000 g TEQ. The quantity reported is rounded to the nearest thousandth (i.e., 0.000 g TEQ), since the smallest unit that the NPRI reporting software will accept for dioxins/furans is 0.001 g TEQ. You would still be required to report the value of "zero".


7.3 Reporting Scenarios

This section provides examples of possible reporting scenarios using the reporting criteria for the alternate-threshold substances.

Example 7: Reporting for a Hospital Waste Incinerator Using Stack Testing Data

At this facility, 200 tonnes of biomedical waste were incinerated during the year, with a waste feed rate of 100 kg/hr. The facility has stack testing data for dioxins/furans. The measured stack gas concentration of dioxins/furans in air was 2.1 ng TEQ/m3. The stack flow rate was 1.2 m3/s. The facility produced 20 tonnes of incinerator ash in the year and has measured an average dioxin/furan concentration of 1.52 mg TEQ/tonne of ash. The ash was shipped off site for disposal in a landfill.

Step 1. Determine if the facility must report to the NPRI for any alternate threshold substances.

Reporting is required by facilities used for the "biomedical or hospital waste incineration of 100 tonnes or more of waste per year", regardless of the number of hours worked by employees. This facility incinerated 200 tonnes of biomedical waste, so a report is required for any substance that met the reporting criterion.

Step 2. Determine which substances and information must be reported.

Dioxins/furans

1. Determine if the measured concentration of dioxin/furan releases to air
(2.1 ng TEQ/m3) was greater than the LoQ of 32 pg TEQ/m3.

Calculation of the measured concentration of dioxin/furan releases to air

This facility is required to report releases of dioxins/furans to air since the measured concentration of 2100 pg TEQ/m3 was greater than the LoQ of 32 pg TEQ/m3.

Calculate the hours of operation.

Calculate the hours of operation

Calculate the quantity of dioxins/furans released to the air.

Calculate the quantity of dioxins/furans released to the air

The substance report for dioxin/furan releases to air would indicate: Basis of Estimate Code - Monitoring or direct measurement (Code M); Detail Code - At or above LoQ (Code AL); Quantity - 0.018 g TEQ. The quantity is rounded to the nearest thousandth (i.e., 0.018 g TEQ), since the smallest unit that the NPRI reporting software will accept for dioxins/furans is 0.001 g TEQ.

2. Determine if the measured concentration of dioxins/furans in the incineration ash (1.52 mg TEQ/tonne ash) was greater than the LoQ of 22 pg TEQ/g ash.

Calculation of the measured concentration of dioxins/furans in the incineration ash

The measured concentration of 1520 pg TEQ/g ash was greater than the LoQ for dioxins/furans in ash of 22 pg TEQ/g ash, therefore the quantity of dioxins/furans in ash transferred off site for disposal must be reported.

3. Calculate the quantity of dioxins/furans contained in the incineration ash that was transferred off site for disposal.

Calculation of the quantity of dioxins/furans contained in the incineration ash that was transferred off site for disposal

The substance report for dioxin/furan transfers off site would indicate: Basis of Estimate Code - Monitoring or direct measurement (Code M); Detail Code - At or above LoQ (Code AL); Quantity - 0.030 g TEQ. The quantity is rounded to the nearest thousandth (i.e., 0.030 g TEQ), since the smallest unit that the NPRI reporting software will accept for dioxins/furans is 0.001 g TEQ

4. Based on process operations, it is known that there were no on-site releases of dioxins/furans to land, water or underground injection resulting from the incineration process. The substance report for dioxin/furan releases to land, water and underground injection would indicate: Basis of Estimate Code - Not applicable (Code NA); Detail Code - not applicable; Quantity - not applicable.

HCB

1. There were no direct measurements performed for HCB at this facility. Use the emission factors provided in the NPRI Emission Factor Database for Alternate- Threshold Substances (Environment Canada) to estimate the HCB releases to air.

Calculation of the quantity released to air

The substance report for HCB releases to air would indicate: Basis of Estimate Code - Emission factors (Code E); Detail Code - not applicable; Quantity - 171.4 g.

2. There was no information available on the concentration of HCB in incinerator ash transferred off site for disposal. The substance report for HCB transferred off site for disposal would indicate: Basis of Estimate Code - No information available (Code NI); Detail Code - not applicable; Quantity - not applicable.

3. Based on unit operations, it is known that there were no on-site releases of HCB to land, water or underground injection resulting from the incineration process. The substance report for HCB releases to land, water and underground injection would indicate: Basis of Estimate Code - Not applicable (Code NA); Detail Code - not applicable; Quantity - not applicable.

Example 8: Reporting for a Cement Kiln

A facility operated a cement kiln and employed 25 full-time employees. Process throughput amounted to 2 500 000 tonnes of clinker produced during the year. The facility incidentally processed and released 9.4 kg of mercury to air from trace mercury contamination in the limestone processed in the kiln and from fossil fuels combusted. The concentration of dioxins/furans released to air was measured at 0.051 ng TEQ/m3, and the total quantity of dioxins/furans released to air from the stack was calculated to be 0.025 g TEQ. The average concentration of HCB released to air over the year was measured at 30.0 ng/m3, and the total quantity of HCB released to air from the stack was calculated to be 9 g.

Step 1. Determine if the facility must report to the NPRI for any alternate threshold substances.

The facility met the 20 000-hour employee threshold and, as such, is required to report to the NPRI for substances which met the NPRI reporting criteria.

Step 2. Determine which substances and information must be reported. Mercury (and its compounds)

The facility incidentally processed and released 9.4 kg of mercury to air. This quantity exceeded the 5-kg manufacture, process or other use threshold for mercury, so the facility must report for mercury (and its compounds).

PAHs

1. Determine if the facility met the NPRI reporting criteria for PAHs. PAHs are reported if the facility incidentally manufactured these substances and the quantity of the PAHs released on site or transferred off site totalled 50 kg or more.

2. In this example, the facility uses the emission factors provided in the Emission Factor Database for Alternate-Threshold Substances (Environment Canada), to calculate the quantities of the individual PAHs that were incidentally manufactured and released or transferred. The quantity of each individual PAH released is added to determine whether the total of the PAHs listed in Schedule 1, Part 3, of the 2000 Canada Gazette notice met or exceeded the 50-kg threshold for total PAHs incidentally manufactured and released or transferred. For a throughput of 2 500 000 tonnes of clinker, the following quantities of individual PAHs are released to air.

Individual PAHs in
Schedule 1, Part 3,
for Which There is
an Emission Factor
Emission Factor
(mg PAHs/tonne
Clinker Produced)
Quantity
(mg)(kg)
Fluoranthene2.426 050 0006.05
Phenanthrene16.942 250 00042.25
Pyrene1.463 650 0003.65
Total51.95

The quantity of the individual PAHs resulting from incidental manufacture totalled more than 50 kg, so the facility has met the reporting threshold for PAHs, and must report these substances.

3. The facility must submit a substance report to the NPRI for each of the three PAH substances for which there are data. The substance reports and quantity reported for on-site releases to air are: 6.05 kg of fluoranthene, 42.25 kg of phenanthrene and 3.65 kg of pyrene. No report is required for the individual PAHs for which there are no emission factors (i.e., benzo(a)anthracene, benzo(a)phenanthrene, etc.). The releases are not reported under the listing "PAHs, total Schedule 1, Part 3" because the facility has information for some of the individual PAHs listed in Schedule 1, Part 3.

4. There were no releases to water, land or underground injection of any incidentally manufactured PAHs, so the facility reports no releases to these media.

5. There is no knowledge of the quantity of incidentally manufactured PAHs in the residue from the pollution control devices (e.g., electrostatic precipitator), so the facility reports no transfers of the three PAHs.

Note: "PAHs, total Schedule 1, Part 3" may only be reported if no information is available for the individual PAH substances listed in Schedule 1, Part 3. Such would be the case if the only emission factor available is for a group of PAH substances or if a monitoring or direct measurement only determined the quantity of a group of PAHs without any data for the individual PAH substances.

Dioxins/furans

1. A direct measurement was used to determine the quantity of dioxins/furans released to air. Compare the measured concentration value to the LoQ for air. The LoQ for releases to air is 32 pg TEQ/m3.

Determine the quantity of dioxins/furans released to air

The concentration of 51 pg TEQ/m3 was above the LoQ for dioxins/furans for air of 32 pg TEQ/m3, therefore the facility is required to report the quantity of dioxins/furans released. The substance report for dioxins/furans released to air would indicate: Basis of Estimate Code - Monitoring or direct measurement (Code M); Detail Code - At or above LoQ (Code AL); Quantity - 0.025 g TEQ.

2. There were no releases of dioxins/furans to water, land or underground injection, nor any transfers off site for disposal. The substance report for dioxin/furan releases to land, water and underground injection would indicate: Basis of Estimate Code - Not applicable (Code NA); Detail Code - not applicable; Quantity - not applicable.

HCB

1. Direct measurement was used to determine releases to air. Compare the measured concentration value to the LoQ for air. The measured concentration of 30 ng/m3 was larger than the LoQ for HCB for air of 6 ng/m3 , so the facility is required to report the quantity released. The substance report for HCB released to air would indicate: Basis of Estimate Code - Monitoring or direct measurement (Code M); Detail Code - At or above LoQ (Code AL); Quantity - 9 g.

2. There were no on-site releases of HCB to water, land or underground injection, nor any transfers off site, so the facility reports no releases to these media or transfers. The substance report for HCB releases to land, water and underground injection would indicate: Basis of Estimate Code - Not applicable (Code NA); Detail Code - not applicable; Quantity - not applicable

Example 9: Using the Manufacture, Process or Other Use Threshold for Reporting Mercury (and its compounds)

The following example illustrates the calculation of the 5-kg manufacture, process or other use reporting threshold applicable to mercury (and its compounds). This facility used several processes in which mercury (and its compounds) were manufactured, processed or otherwise used. There is no 1% concentration exemption for mercury (and its compounds). Mercury (and its compounds), at any concentration, must be considered when calculating the reporting threshold and subsequently when reporting.

The facility met the 20 000-hour employee threshold and the processes used were:

  1. In the first process, mercury was present in a mixture at a 1% concentration.
  2. The facility received a raw material which contained 0.005% mercury, which was processed in stream 2.
  3. In process stream 3, mercury was present at a concentration of 0.01%.
Material Containing MercuryTotal Weight of Material Containing Mercury
(tonnes)
Concentration of Mercury in the MaterialNet Weight of Mercury
(tonnes)
Process stream 11         1.0%         0.01
Process stream 2
(raw material)
50         0.005%         0.0025
Process stream 320         0.01%         0.02
 Total weight of mercury0.0325
(32.5 kg)

In this example, the facility would be required to submit a report to the NPRI for mercury (and its compounds) because the total quantity manufactured, processed or otherwise used at the facility exceeded the 5-kg reporting threshold. The facility must report the quantity released on site and transferred off site.