Road dust emissions from unpaved surfaces: guide to reporting

Purpose

To provide facilities guidance on how to report road dust emissions from unpaved surfaces to the National Pollutant Release Inventory (NPRI). An Unpaved Industrial Road Dust Calculator and Unpaved Road Dust Calculation Flowchart come with this guidance in order to perform and to explain the method of calculation.

NOTE: The calculator is used for calculating the emissions from one segment road at a time.

Background Information

 What is the reporting threshold?

The reporting threshold for estimating emissions of Total Particulate Matter (TPM), Particulate Matter less than or equal to 10 microns in diameter (PM10) and Particulate Matter less than or equal to 2.5 microns in diameter (PM2.5) from unpaved road surfaces  is 10 000 Vehicle Kilometres Travelled (VKT) within the facility in a given calendar year. Figure 1 shows the procedure and criteria for estimating TPM, PM10 and PM2.5 emissions from unpaved road surfaces.

Figure 1: Flow Diagram for Estimating TPM, PM10 and PM2.5 from Unpaved Road Surfaces

Contiguous facility with activity of 20000 hours or more OR Contiguous facility with activity to which 20000 hours does not apply „³ VKT on unpaved surfaces within a facility per year if NO Do not include TPM, PM10 or PM2.5 emissions from other sources must still be calculated and compared to reporting requirements. If YES Include TPM, PM10, and PM2.5 emissions from unpaved road surfaces while calculating the respective thresholds. If the threshold for TPM, PM10 and PM2.5 are exceeded, the reports must include emissions from road dust and other sources.

More details regarding the general criteria for reporting substances listed in Part 4 (including particulate matter) can be found in the Guide for Reporting to the National Pollutant Release Inventory available online.

What is considered an unpaved road?

The common types of unpaved road surfaces include: gravel road surfaces, thin membrane bituminous, surface treatments and bituminous cold mix surfaces. If a dust suppressant is applied to an unpaved road, this segment of road is still considered an unpaved road surface. A paved road is defined as any road that has semi-permanent surface placed on it such as asphalt or concrete.

Estimation of Road Dust Emissions from Unpaved Road Surfaces

The annual emission estimates can be obtained using the following generalized equation (USEPA, 2006):

Ex = VKT*EFx*ADJ*(1-CE/100) (1)

Where:

Ex: Emission of contaminant x, kg;

VKT: Annual total vehicle kilometres travelled, km;

EFx.: Emission factor of contaminant x, kg/VKT;

ADJ: Adjustment factor for precipitation, snow cover and frozen days;

CE: Applied Dust Control Method’s efficiency, %.

The emission factor for unpaved road surfaces is based on an empirical analysis of test data correlating the emissions to vehicle characteristics taking into account the silt content of the roadway and mean weight of the vehicles traveling on the road. The VKT represents the kilometres travelled by the vehicle fleet operated at the facility on unpaved roads. Facilities should consider all vehicles either owned and/or operated within the boundaries of the facility (The customer’s vehicles must also be considered). This includes all vehicles that come into the facility through some form of controlled access such as a security gate, including any contractor vehicles brought on site as a result of a request of the facility owner/operator or customers. All other vehicles that enter the site through uncontrolled access (e.g. Public right-of-way, crown land access, etc.) are not to be included in either the threshold calculation or the final release estimates.  The facility has no control over the road dust these vehicles generate.For the purpose of NPRI reporting, “vehicle” refers to any mobile equipment that is capable of self-propulsion (e.g., fleet vehicles and earth moving equipment including, but not limited to, loaders, dump trucks, forklifts, excavators and bulldozers). VKT and EFx can be obtained using the equations presented below.

Annual Total Vehicle Kilometres Travelled (VKT)

VKT = Average Daily Traffic x Length of Unpaved Roads x Operating Days/Year (2)

The average daily traffic is the total count of vehicle passes over the road segments per day. The Vehicle Kilometres Travelled (VKT) should be obtained with the best available data like odometer readings, length of roads within the facility and number of vehicles coming into the facility on a typical day. If no data is available, surveys can be conducted throughout the year on representative days of operation to estimate the total VKT. The calculation of VKT is detailed in the Facility Informationsheet under the Unpaved Industrial Road Dust Calculator.

Emission Factor (EF) for Emissions of TPM, PM10 and PM2.5 from Unpaved Road Surfaces

USEPA has developed an empirical equation for vehicles travelling on unpaved road surfaces at industrial sites (for more details refer to AP 42, Chapter 13: Miscellaneous Sources, Section 2.2, (USEPA, 2006)). The emission factor in metric units (i.e. kilograms/VKT) is calculated by the following equation:

EF = k (s/12)a (W/2.72)b (3)

Where:

EF: Size-specific emission factor, kg/VKT;

s: Surface material silt content, %;

W: Mean vehicle weight, tonnes (metric);

k, a, b:  Numerical constants for calculation.

Note:

  • The term (W/2.72) in equation (3) has been modified from the original term (W/3) in the AP-42 equation to allow for metric vehicle weights. This calculation can be found in the Uncontrolled Emissions sheet under the Unpaved Industrial Road Dust Calculator.
  • The facility may have unpaved roads that are only travelled by light vehicles, in this case the equation 1b given by the USEPA for public unpaved roads, traveled mostly by light-duty vehicles with mean vehicle weights less than 2.7 tonnes may be used (AP 42, Chapter 13: Miscellaneous Sources, Section 13.2.2.2, (USEPA, 2006)).
Table 1: Numerical constants used in the unpaved industrial road dust emission factor.
Constant PM2.5 PM10 TPM
k (kg/VKT) 0.042 0.423 1.381
a 0.9 0.9 0.7
b 0.45 0.45 0.45

The silt content (i.e. “s”) may be obtained by using the US EPA test method (Appendix C.1: Procedures for sampling surface/Bulk dust loading, AP-42,US EPA, 2003). However, in the absence of site-specific value for the silt content, an appropriate mean value from Table AP-42 13.2.2-1 (US EPA, 2006) may be used as a default value. However, the use of such default values may affect the quality of estimated values. It is important to note that the vehicle-related source conditions refer to the average weight, speed, and number of wheels for all vehicles travelling the road. For example, if 86 percent of traffic on the road is 300-tonne trucks while the remaining 14 percent consists of 55-tonne trucks, then the mean weight is 265 tonnes (0.86 x 300 + 0.14 x 55). More specifically, the above EF equation is not intended to be used to calculate a separate emission factor for each vehicle class within a mix of traffic on a given unpaved road.

 Precipitation and Snow Cover Corrections

The road dust emissions are reduced due to the natural mitigation of precipitation (rain and snow falls) and frozen and covered roads with snow. Frozen ground can have a suppressing effect on dust emissions depending on the type of road and the amount of traffic. Frozen ground minimizes the breakdown of the travel surface leaving less material to be entrained in the air as vehicles pass. In using equation 1, it is assumed no dust emissions occurred on days with precipitation exceeding 0.2 mm and on days when the road surface is covered with snow or frozen without high traffic volume.

The adjustement factor ADJ in equation 1 is defined as:

ADJ = (Working Days-(p+snow))/Working Days (4)

Where:

ADJ: Adjustment factor for precipitation, snow cover and frozen days;

Working Days: The number of operating days per year;

p: Estimated Annual Working Days with precipitation exceeding 0.2 mm;

snow: The estimated Annual Working Days when the roads were frozen or snow covered and wet for winter.

Information about precipitation and snow cover is filled in the Facility information sheet under the Unpaved Industrial Road Dust Calculator. The calculation of ADJ is then retrieved in the Annual Emissions sheet. The facility may use its own information if it is available. However, the information about precipitation and snow cover may be taken from the nearest meteorological station in the Environment Canada’s Historical Climate Data website. The facility may use the climate normals Data between 1971 to 2000, or may retrieve the information from the Monthly Climate Summaries for the reporting year. It is worth noting that the retrieved information, from the Climate Normals Data, should be for the days with precipitation exceeding 0.2 mm and the days with snow depth more than 1 cm.

When calculating ADJ using the Environment Canada’s climate Data, attention must be given to the sum of precipitation and snow cover days and the working days. So, when using the Climate Data verify if the ''p+snow'' for a specific month does not exceed the number of days worked for that month. Otherwise, use the number of days worked instead of sum of p and snow for that month. For more details, refer to the Example Scenario. Ex: if the Working Days for December are 20 days and "p+snow" is more than 20 days for this month, then use 20 days for December in order to calculate the total annual "p+snow".

Dust Control Methods

Several techniques are used to reduce road dust emissions caused by vehicular travel on industrial unpaved road surfaces, such as water or chemical dust suppressants (Buonicore and Davis, 1992;

USEPA, 1987). Watering is the most common control technique used for unpaved road surfaces (AMEC, 2007). However, control efficiency depends on the application rate of water, elapsed time between applications, traffic volume and meteorological conditions. More information about water suppression efficiencies can be found in the “Dust Control Methods” sheet under the Unpaved IndustrialRoad Dust Calculator. Chemical stabilization is also a technique used to reduce emissions of road dust from unpaved surfaces, however its control efficiency is dependent on the material used and the method of application. The facility should consult with the vendor to obtain the control efficiency for a specific chemical stabilization process used within the facility. In a recent test report, average performance curves for petroleum resin products, used on unpaved road surfaces, were generated and more details can be found in Figure 13.2.2-5, AP-42 chapter 13.2.2 (USEPA, 2006). Efficiencies of chemical dust suppressants are provided in the Dust Control Methodssheet under the Unpaved IndustrialRoad Dust Calculator. Additionally, this section of the calculator also allows facilities to use their own dust control information.

Example Scenario

Facility XYZ is an open-pit copper-gold mine located in northern British Columbia in operation all year round (seven days per week, 24h hours per day). Copper and gold ore are extracted from two pits, A and B, and hauled back to the facility mill. Pit A is located 300 m from the mill and pit B, 200 m. The unpaved road between the facility mill and the facility entrance gate is 100-meter long and is used by concentrate hauling and other facility vehicles. Calculation about dust emissions from the facility XYZ unpaved road segments can be found in the attached Unpaved Industrial RoadDust Calculator facility XYZ example files

NOTE : The information stated here is fictitious and its objective is only to explain the process of industrial unpaved road dust calculation.

From laboratory test, the amount of silt content for the road segments was determined as follows:

Haul road from Pit A to mill: 10 %

Haul road from pit B to mill: 9 %

Unpaved road from gate to mill: 5 %

Vehicle Data information

Segment road #1: Pit A - Mill

Ore Hauling

Segment length: 0.3 km

Empty weight: 200 tonnes

Full weight: 400 tonnes

Average weight: 300 tonnes

Number of Trucks: 6 Haul trucks

Average number of round trips/day: 10

Segment road #2: Pit B - Mill

Ore Hauling

Segment length: 0.2 km

Empty weight: 200 tonnes

Full weight: 400 tonnes

Average weight: 300 tonnes

Number of Trucks: 5 Haul trucks

Average number of round trips/day: 10

Segment road #3: Facility unpaved road from the mill to the gate

Segment length: 0.1 km

Concentrate hauling

Empty weight: 20 tonnes

Full weight: 60 tonnes

Average weight: 40 tonnes

Number of Trucks: 6 Haul trucks

Average number of round trips/day: 2

Other vehicles (Employee and customer vehicles)

Empty weight: 2 tonnes

Full weight: 2 tonnes

Average weight: 2 tonnes

Number of vehicles: 30

Average number of round trips/day: 1

Step 1

Annual Total Vehicle Kilometres Travelled (VKT):

The first step is to identify if the facility meets the threshold of 10 000 annual total Vehicle Kilometres Travelled (VKT). In this scenario it is assumed that haul road segments A and B, and the gate to mill road segment are one round trip routes. That is, all road segments are effectively single lane roads.  As an example, when a vehicle travels on road segment #1 to go from the mill to pit A, it returns to the mill on the same road segment.Therefore, a multiplier of 2 will be used for the length of this trip in the following equation:

1. Estimate the annual VKT for each vehicle type using the same unpaved road segment from Equation (2):

Average daily traffic = 2 x (Number of vehicle-type round trips/day) x (Number of vehicles/type)

VKT vehicle-type/segment road = Average daily traffic x (Number of operating days/year) x (Segment length)

2. Calculate the annual VKT for each segment by summing all annual VKT of vehicles types using this segment road

VKT segment road = VKT vehicle-type 1 + VKT vehicle-type 2 +…

3. Calculate the Annual Total VKT by summing all annual VKT for all road segments

Total VKT = VKT segment road 1 + VKT segment road 2 +…

4. Check if the Annual Total VKT is more than 10 000 km travelled

If the facility’s Total VKT > 10 000, then road dust emissions must be considered.

Segment road #1: Pit A - Mill

  • Estimate the annual VKT for each vehicle type on unpaved segment road #1

One vehicle type:

Ore Hauling

VKTvehicle-type 1/segment road 1 = 2 x 10 (round trips of vehicle-type 1/day) x 6 (vehicles/type) x

0.3 km x 365 (days/year)

VKTvehicle-type 1/segment road 1 = 13 140 km/year

  • Calculate the annual VKT for segment road 1 by summing all annual VKT of vehicles types using this segment road

There is only one vehicle type using this segment, then:

VKTsegment road 1 = VKT vehicle-type 1/segment road 1 = 13 140 km/year

Segment road #2: Pit B - Mill

  • Estimate the annual VKT for each vehicle type on unpaved segment road #2

One vehicle type:

Ore Hauling

VKTvehicle-type 1/segment road 2 = 2 x 10 (round trips of vehicle-type 1/day) x 5 (vehicles/type) x

0.2 km x 365 (days/year)

VKTvehicle-type 1/segment road 2 = 7 300 km/year

  • Calculate the annual VKT for segment road 2 by summing all annual VKT of vehicles types using this segment road

There is only one vehicle type using this segment, then:

VKTsegment road 2 = VKT vehicle-type 1/segment road 2 = 7 300 km/year

Segment road #3: Facility unpaved road from the mill to the gate

  • Estimate the annual VKT for each vehicle type on unpaved segment road #3

Two vehicle types:

Concentrate hauling

VKTvehicle-type 1/segment road 3 = 2 x 2 (round trips of vehicle-type 1/day) x 6 (vehicles/type) x

0.1 km x 365 (days/year)

VKTvehicle-type 1/segment road 3 = 876 km/year

Other vehicles

VKTvehicle-type 2/segment road 3 = 2 x 1 (round trip of vehicle-type 2/day) x 30 (vehicles/type) x

0.1 km x 365 (days/year)

VKTvehicle-type 2/segment road 3 = 2 190 km/year

  • Calculate the annual VKT for segment road 2 by summing all annual VKT of vehicles types using this segment road

There are two vehicle types using this segment, then:

VKTsegment road 3 = VKT vehicle-type 1/segment road 3 + VKTvehicle-type 2/segment road 3 = 3 066 km/year

Annual total VKT

  • Calculate the Annual Total VKT by summing all annual VKT for all road segments

Total VKT =VKT segment road 1 + VKT segment road 2 + VKTsegment road 3

Total VKT = 13 140 km + 7 300 km + 3 066 km

Total VKT = 23 506 VKT

Because the Total VKT for the facility is greater than 10 000 km, the facility must consider the particulate matter emissions from road dust in their NPRI reporting.

Step 2

Mean vehicle weight (W)

The weighted vehicles’ weight (Wfleet) on a specific road segment road can be calculated as follows:

1. Calculate the average weight of each vehicle type on the unpaved road segment

Wvehicle type = (W(Empty) vehicle type + W(Full) vehicle type)/2 (5)

2. Calculate the percentage of each vehicle type traffic (Pvehicle type) on the unpaved segment road

Pvehicle type =  VKTvehicle type/segment road/VKTsegment road (6)

3. Calculate the fleet weight for the unpaved segment road

Wfleet = Wvehicle type1 x Pvehicle type 1 + Wvehicle type 2 x Pvehicle type2 + …

Segment road #1: Pit A - Mill

¡P Calculate the average weight of each vehicle type using the unpaved segment road

There is only one vehicle type using this segment, then:

Wvehicle type1 = (200 tonnes+ 400 tonnes)/2

Wvehicle type1 = 300 tonnes

  • Calculate the percentage of each vehicle type traffic on the unpaved segment road

From step 1, VKT vehicle-type 1/segment road 1 = 13 400 km and VKTsegment road 1 = 13 400 km; therefore

Pvehicle type1 = 13 400 km / 13 400 km

Pvehicle type1 = 1

  • Calculate the fleet weight for the unpaved segment road

Wfleet = Wvehicle type1 x Pvehicle type 1

Wfleet = 300 tonnes x 1

Wfleet = 300 tonnes

Segment road #2: Pit B - Mill

  • Calculate the average weight of each vehicle type using the unpaved segment road

There is only one vehicle type using this segment, then:

Wvehicle type1 = (200 tonnes+ 400 tonnes)/2

Wvehicle type1 = 300 tonnes

  • Calculate the percentage of each vehicle type traffic on the unpaved segment road

From step 1, VKT vehicle-type 1/segment road 2 = 7 300 km and VKTsegment road 2 = 7 300km; therefore,

Pvehicle type1 = 7 300 km/ 7 300 km

Pvehicle type1 = 1

  • Calculate the fleet weight for the unpaved segment road

Wfleet = Wvehicle type1 x Pvehicle type 1

Wfleet = 300 tonnes x 1

Wfleet = 300 tonnes

Segment road #3: Facility unpaved road from the mill to the gate

  • Calculate the average weight of each vehicle type using the unpaved segment road

There are two vehicle types using this segment, then:

Wvehicle type 1 = (20 tonnes+ 60 tonnes)/2

Wvehicle type 1 = 40 tonnes

Wvehicle type 2 = (2 tonnes+ 2 tonnes)/2

Wvehicle type 2 = 2 tonnes

  • Calculate the percentage of each vehicle type traffic on the unpaved segment road

From step 1, VKT vehicle-type 1/segment road 3 = 876 km, VKTvehicle-type 2/segment road 3 = 2 190 km and VKT segment road 3 = 3 066 km/year; therefore,

Pvehicle type 1 = 876 km /3066 km

Pvehicle type1 = 0.286

Pvehicle type 2 = 2190 km /3066 km

Pvehicle type 2 = 0.714

  • Calculate the fleet weight for the unpaved segment road

Wfleet = Wvehicle type 1 x Pvehicle type 1 + Wvehicle type 2 x Pvehicle type 2

Wfleet = 40 tonnes x 0.286 + 2 tonnes x 0.714

Wfleet = 12.857 tonnes

Step 3

Road segments’ uncontrolled emission estimation

The uncontrolled emissions (see equation (1)) are estimated separately for each road segment using equation (3) (given below for reference) for emission factors and the annual VKT from each road segment calculated in STEP 2.

EF = k (s/12)a (W / 2.72)b (3)

For each road segment, the emission factors from equation (3) are calculated based on its weighted fleet weight (W) from step 3 and its silt content (s).

Segment road #1: Pit A - Mill:

Emission factors:

EFTPM = 1.381* (10/12)0.7 x (300/2.72)0.45 = 10.093 kg/VKT

EFPM10 = 0.423* (10/12)0.9 x (300/2.72)0.45 = 2.979 kg/VKT

EFPM2.5 = 0.042* (10/12)0.9 x (300/2.72)0.45 = 0.298 kg/VKT

Note:  The constant (k) and exponents (a and b) are obtained from Table 1.

Uncontrolled emissions:

ETPM = 13 140 VKT x 10.093 (kg/VKT) x (1 tonne/1 000 kg) = 132.620 tonnes

EPM10 = 13 140 VKT x 2.979 (kg/VKT) x (1 tonne/1 000 kg) = 39.114 tonnes

EPM2.5= 13 140 VKT x 0.298 (kg/VKT) x (1 tonne/1 000 kg) = 3.914 tonnes

Segment road #2: Pit B - Mill

Emission factors:

EFTPM = 1.381* (9/12)0.7 x (300/2.72)0.45 = 9.375 kg/VKT

EFPM10 = 0.423* (9/12)0.9 x (300/2.72)0.45 = 2.710 kg/VKT

EFPM2.5 = 0.042* (9/12)0.9 x (300/2.72)0.45 = 0.271 kg/VKT

Uncontrolled emissions:

ETPM = 7 300 VKT x 9.375 (kg/VKT) x (1 tonne/1 000 kg) = 68.439 tonnes

EPM10 = 7 300 VKT x 2.710 (kg/VKT) x (1 tonne/1 000 kg) = 19.779 tonnes

EPM2.5= 7 300 VKT x 0.271 (kg/VKT) x (1 tonne/1 000 kg) = 1.978 tonnes

Segment road #3: Facility unpaved road from the mill to the gate

Emission factors:

EFTPM = 1.381* (5/12)0.7 x (12.857/2.72)0.45 = 1.506 kg/VKT

EFPM10 = 0.423* (5/12)0.9 x (12.857/2.72)0.45 = 0.387 kg/VKT

EFPM2.5 = 0.042* (5/12)0.9 x (12.857/2.72)0.45 = 0.039 kg/VKT

Uncontrolled emissions:

ETPM = 3066 VKT x 1.506 (kg/VKT) x (1 tonne/1 000 kg) = 4.616 tonnes

EPM10 = 3066 VKT x 0.387 (kg/VKT) x (1 tonne/1 000 kg) = 1.186 tonnes

EPM2.5= 3066 VKT x 0.039 (kg/VKT) x (1 tonne/1 000 kg) = 0.119 tonnes

Step 4

The following paragraph describes adjustment calculations for precipitation and snow cover corrections and application of the specified dust control method.

Precipitation and snow cover correction

The reduction of emissions due to precipitation and snow cover is accounted for by adjusting the uncontrolled emissions estimated in STEP 3 using the equation below which is applied for each road segment separately.

EAdjusted due to precipitation and snow cover = EUncontrolled x ADJ (7)

Where:

E: Emissions (tonnes);

ADJ: Adjustment factor given in equation 4.

Using the Unpaved Industrial Road Dust Calculator for each road segment,the adjustment of the uncontrolled emissions is done based on the Canadian Climate averages precipitation and snow cover data. This exercise leads to average adjusted emissions for precipitation and snow cover.

The precipitation and snow cover data for the facility XYZ, were taken from the nearest meteorological station SMITHERS A, BC.

These retrieved climate normals are reported in Table 2. And they are adjusted in order to take into account the possible situations when the "p+snow" days are beyond the working days

Table 2: Adjusted p+snow for the facility XYZ using the information for the meteorological station SMITHERS A, BC .
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

Days with Precipitation

( ≥ 0.2 mm)

15.8 12.7 11.2 9.5 11.7 13.8 11.9 12.2 13.2 17.5 16.1 16.6 162.1

Days with Snow Depth

( ≥ 1 cm )

30.8 27.3 22.8 3.9 0.03 0 0 0 0 1.3 15.1 29.1 130..2
"p+snow" 46.6 40 34 13.4 11.73 13.8 11.9 12.2 13.2 18.8 31.2 45.7 292.3

Adjustement to a maximum

Worked Days (*)

31 29 31 --- --- --- --- --- --- --- 30 31 ---

Adjusted

"p+snow"

31 29 31 13.4 11.73 13.8 11.9 12.2 13.2 18.8 30 31 247.03

(*) the "p+snow" must not exceed the monthly Working Days. (The facility XYZ worked 12 months/year).

Based on the adjusted p+snow in Table 2 equal to 247.03 days and the number of Working Days equal to 365 days, the adjustment for precipitation and snow cover is:

ADJ = (365-247.03)/365

= 32 %

The above calculation is reported in the attached Unpaved Industrial RoadDust Calculator facility XYZ example files.

Dust control methods

The reduction of emissions by applying dust control methods is accounted for by multiplying the already adjusted emissions for precipitation and snow cover by the efficiency factor (1-CE/100):

EControlled = EAdjusted due to precipitation and snow cover x (1-CE/100) (8)

Where:

E: Emissions (tonnes);

CE: Control efficiency given in the Dust Control Methods sheet under the Unpaved Industrial Road Dust Calculator, %.

To control dust emissions, the facility XYZ applied watering more than twice a day (CE = 70 %). The calculation is detailed in the attached Unpaved Industrial RoadDust Calculator facility XYZ example files under Dust Control Methodssheet.

Table 3 summarizes the adjusted emissions that account for precipitation, snow cover and dust control application. Detailed information about these emissions can be found in the attached Unpaved Industrial RoadDust Calculator facility XYZ example files under Annual Emissions sheet.

Table 3: Total adjusted for rain and snow and controlled unpaved road dust emissions
 

Segment road 1

(tonnes)

Segment road 2

(tonnes)

Segment road 3

(tonnes)

Total

(tonnes)

TPM 12.859 6.636 0.448 19.943
PM10 3.795 1.918 0.115 5.828
PM2.5 0.380 0.192 0.012 0.584

Quality Control

To enhance the quality of the reported unpaved industrial road dust emissions, the facility must ensure that the ratios for their emissions for each unpaved road are respected according to the equations 9 and 10. The ratio between the unpaved industrial road dust emissions factors are as follows:

EFPM10/EF PM2.5 = (0.423*(s/12)0.9(W/2.72)0.45)/(0.0423*(s/12) 0.9(W/2.72)0.45)

= 10 (9)

EFTPM/EF PM10 = (1.381*(s/12)0.7(W/2.72)0.45)/(0.423*(s/12) 0.9(W/2.72)0.45)

= 3.26*(s/12)-0.2 (10)

For equation 10, the ratio depends on each facility’s unpaved road silt content. According to AP-42, Chap 13, the range of silt content used for developing the unpaved industrial road dust equation is [1.8, 25.2] which lead to a ratio of EFTPM/EFPM10 varying from 2.81 to 4.76 for that range.

Step 5

 The TPM, PM10 and PM2.5emissions from unpaved road segments reported in Table 3 will be added to the other facility sources of TPM, PM10 and PM2.5 in order to check if their respective NPRI thresholds are met.

Facility XYZ has other emissions of Particulate Matter from other sources (mineral processing point emissions and storage and handling). The facility has no stacks more than 50 m and the published emission factors were used to estimate Particulate Matter emission from the other activities.  The calculations are not shown in the guidance document, but are summarized in Table 4 for reference only.

Table 4: Does the Facility’s Annual Emissions Meet the NPRI Reporting Thresholds
 

Road dust

(tonnes)

Stack emissions

(tonnes)

Storage and

handling

(tonnes)

Total

(tonnes)

NPRI

Thresholds

(tonnes)

NPRI Threshold

Exceeded (?)

TPM 19.934 15.450 1.470 36.854 20 Yes
PM10 5.828 8.850 0.560 15.238 0.5 Yes
PM2.5 0.584 2.500 0.120 3.204 0.3 Yes

Step 6

 Since the emissions of TPM, PM10and PM2.5 exceed their respective thresholds the facility XYZ must report these substances to the NPRI. The road dust emissions reporting in OWNERS will be as follow:

Releases to Air of TPM Not Including Road Dust
  Basis of Estimate Quantity (tonnes)
Stack or Point Releases E2-Published emission factors 15.450
Storage or Handling Release E2-Published emission factors 1.470


Releases to Air of TPM Including Road Dust
  Basis of Estimate Quantity (tonnes)
NPRI Road Dust E2-Published emission factors 19.934

Total - Releases to Air

(Including NPRI road dust)

-- 36.854


Releases to Air of PM10 Not including Road Dust
  Basis of Estimate Quantity (tonnes)
Stack or Point Releases E2-Published emission factors 8.850
Storage or Handling Release E2-Published emission factors 0.560


Releases to Air of PM10 Including Road Dust
  Basis of Estimate Quantity (tonnes)
NPRI Road Dust E2-Published emission factors 5.828
Total - Releases to Air (Including NPRI road dust) -- 15.238


Releases to Air of PM2.5 Not Including Road Dust
  Basis of Estimate Quantity (tonnes)
Stack or Point Releases E2-Published emission factors 2.500
Storage or Handling Release E2-Published emission factors 0.120


Releases to Air of PM2.5Including Road Dust
  Basis of Estimate Quantity (tonnes)
NPRI Road Dust E2-Published emission factors 0.584

Total - Releases to Air

(Including NPRI road dust)

-- 3.204

REFERENCES

AMEC (2007) The development of methodology, Activity Data and emission factors for estimating fugitive particulates from the aggregate mining and rock quarrying sector, AMEC Earth & Environmental, Internal report submitted to Environment Canada, Hamilton, Ontario, Canada.

Buonicore and Davis (1992) Fugitive Emissions. Air Pollution Engineering Manual, Chapter 4, First Edition. AWMA, New York, USA.

EPA (2006) Unpaved Roads-Chapter 13.2.2, AP-42, Compilation of Air Pollutant Emission Factors, Volume 1, Stationary Point and Area Sources, USEPA, USA.

EPA (2003) Appendix C.1: Procedures for sampling surface/Bulk dust loading, AP-42, Compilation of Air Pollutant Emission Factors, Volume 1, Stationary Point and Area Sources, USEPA, USA.

EPA (1987) Emission Control technologies and emission factors for unpaved road fugitive emissions, User’s Guide, EPA/625/5-87/022, USEPA, USA.

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