# 40 CFR 98.323 - Calculating GHG emissions.

*4*from multiple shafts and/or vent holes are collected, you must calculate the quarterly CH

*4*liberated from the ventilation system using Equation FF-1 of this section. You must measure CH

*4*content, flow rate, temperature, pressure, and moisture content of the gas using the procedures outlined in § 98.324.

*4V*= Quarterly CH

*4*liberated from a ventilation monitoring point (metric tons CH

*4*).

*H*

*2*

*O*)

*n*when V is measured on a wet basis and C is measured on a dry basis.

*H*

*2*

*O*)] when V is measured on a dry basis and C is measured on a wet basis.

*H*

*2*

*O*) = Moisture content of the methane emitted during the measurement period, volumetric basis (cubic feet water per cubic feet emitted gas).

*4*concentration of ventilation gas for the quarter (%).

*4*at 520 °R (60 °F) and 1 atm (lb/scf).

*2*O), if applicable, must be based on measurements taken at least once each quarter with no fewer than 6 weeks between measurements. If measurements are taken more frequently than once per quarter, then use the average value for all measurements taken. If continous measurements are taken, then use the average value over the time period of continuous monitoring.

*4*liberated from ventilation systems (CH

*4VTotal*) as the sum of the CH

*4*from all ventilation monitoring points in the mine, as follows:

*4VTotal*= Total quarterly CH

*4*liberated from ventilation systems (metric tons CH

*4*).

*4V*= Quarterly CH

*4*liberated from each ventilation monitoring point (metric tons CH

*4*).

*4*from multiple wells and/or vent holes are collected), you must calculate the weekly CH

*4*liberated from the mine using CH

*4*measured weekly or more frequently (including by CEMS) according to 98.234(c), CH

*4*content, flow rate, temperature, pressure, and moisture content, and Equation FF-3 of this section.

*4D*= Weekly CH

*4*liberated from at the monitoring point (metric tons CH

*4*).

*i*= Measured volumetric flow rate for the days in the week when the degasification system is in operation at that monitoring point, based on sampling or a flow rate meter (cfm). If a flow rate meter is used and the meter automatically corrects for temperature and pressure, replace “520°R/T

*i*× P

*i*/1 atm” with “1”.

*i*= Moisture correction factor for the measurement period, volumetric basis.

*i*and C

*i*are measured on a dry basis or if both are measured on a wet basis.

*2*O)

*i*when V

*i*is measured on a wet basis and C

*i*is measured on a dry basis.

*2*O)

*i*] when V

*i*is measured on a dry basis and C

*i*is measured on a wet basis.

*2*O) = Moisture content of the CH

*4*emitted during the measurement period, volumetric basis (cubic feet water per cubic feet emitted gas)

*i*= CH

*4*concentration of gas for the days in the week when the degasification system is in operation at that monitoring point (%).

*4*at 520 °R (60 °F) and 1 atm (lb/scf).

*i*= Temperature at which flow is measured (°R).

*i*= Pressure at which flow is measured (atm).

*2*O), if applicable, must be based on measurements taken at least once each calendar week with at least 3 days between measurements. If measurements are taken more frequently than once per week, then use the average value for all measurements taken that week. If continuous measurements are taken, then use the average values over the time period of continuous monitoring when the continuous monitoring equipment is properly functioning.

*4*liberated from degasification systems for the mine should be determined as the sum of CH

*4*liberated determined at each of the monitoring points in the mine, summed over the number of weeks in the quarter, as follows:

*4DTotal*= Quarterly CH

*4*liberated from all degasification monitoring points (metric tons CH

*4*).

*4D*= Weekly CH

*4*liberated from a degasification monitoring point (metric tons CH

*4*).

*4*destroyed for each destruction device and each point of offsite transport to a destruction device, using Equation FF-5 of this section. You must measure CH

*4*content and flow rate according to the provisions in § 98.324, and calculate the methane routed to the destruction device (CH

*4*) using either Equation FF-1 or Equation FF-3 of this section, as applicable.

*4Destroyed*= Quarterly CH

*4*destroyed (metric tons).

*4*= Quarterly CH

*4*routed to the destruction device or offsite transfer point (metric tons).

*4*destroyed as the sum of the methane destroyed at all destruction devices (onsite and offsite), using Equation FF-6 of this section.

*4DestroyedTotal*= Quarterly total CH

*4*destroyed at the mine (metric tons CH

*4*).

*4Destroyed*= Quarterly CH

*4*destroyed from each destruction device or offsite transfer point.

*4*emissions to the atmosphere using Equation FF-7 of this section.

*4*emitted (net)= Quarterly CH

*4*emissions from the mine (metric tons).

*4VTotal*= Quarterly sum of the CH

*4*liberated from all mine ventilation monitoring points (CH

*4V*), calculated using Equation FF-2 of this section (metric tons).

*4DTotal*= Quarterly sum of the CH

*4*liberated from all mine degasification monitoring points (CH

*4D*), calculated using Equation FF-4 of this section (metric tons).

*4DestroyedTotal*= Quarterly sum of the measured CH

*4*destroyed from all mine ventilation and degasification systems, calculated using Equation FF-6 of this section (metric tons).

*2*emissions using Equation FF-8 of this section.

*2*= Total quarterly CO

*2*emissions from CH

*4*destruction (metric tons).

*4Destroyedonsite*= Quarterly sum of the CH

*4*destroyed, calculated as the sum of CH

*4*destroyed for each onsite, non-energy use, as calculated individually in Equation FF-5 of this section (metric tons).

*2*to CH

*4*.

(a) For each ventilation shaft, vent hole, or centralized point into which CH4 from multiple shafts and/or vent holes are collected, you must calculate the quarterly CH4 liberated from the ventilation system using Equation FF-1 of this section. You must measure CH4 content, flow rate, temperature, pressure, and moisture content of the gas using the procedures outlined in § 98.324.

(1) Consistent with MSHA inspections, the quarterly periods are:

(i) January 1-March 31.

(ii) April 1-June 30.

(iii) July 1-September 30.

(iv) October 1-December 31.

(2) Values of V, C, T, P, and (fH2O), if applicable, must be based on measurements taken at least once each quarter with no fewer than 6 weeks between measurements. If measurements are taken more frequently than once per quarter, then use the average value for all measurements taken. If continuous measurements are taken, then use the average value over the time period of continuous monitoring.

(3) If a facility has more than one monitoring point, the facility must calculate total CH4 liberated from ventilation systems (CH4VTotal) as the sum of the CH4 from all ventilation monitoring points in the mine, as follows:

(b) For each monitoring point in the degasification system (this could be at each degasification well and/or vent hole, or at more centralized points into which CH4 from multiple wells and/or vent holes are collected), you must calculate the weekly CH4 liberated from the mine using CH4 measured weekly or more frequently (including by CEMS) according to 98.234(c), CH4 content, flow rate, temperature, pressure, and moisture content, and Equation FF-3 of this section.

(1) Values for V, C, T, P, and (fH2O), if applicable, must be based on measurements taken at least once each calendar week with at least 3 days between measurements. If measurements are taken more frequently than once per week, then use the average value for all measurements taken that week. If continuous measurements are taken, then use the average values over the time period of continuous monitoring when the continuous monitoring equipment is properly functioning.

(2) Quarterly total CH4 liberated from degasification systems for the mine should be determined as the sum of CH4 liberated determined at each of the monitoring points in the mine, summed over the number of weeks in the quarter, as follows:

(c) If gas from a degasification system or ventilation system is sold, used onsite, or otherwise destroyed (including by flaring or VAM oxidation), you must calculate the quarterly CH4 destroyed for each destruction device and each point of offsite transport to a destruction device, using Equation FF-5 of this section. You must measure CH4 content and flow rate according to the provisions in § 98.324, and calculate the methane routed to the destruction device (CH4) using either Equation FF-1 or Equation FF-4 of this section, as applicable.

(1) Calculate total CH4 destroyed as the sum of the methane destroyed at all destruction devices (onsite and offsite), using Equation FF-6 of this section.

(2) [Reserved]

(d) You must calculate the quarterly measured net CH4 emissions to the atmosphere using Equation FF-7 of this section.

(e) For the methane collected from degasification and/or ventilation systems that is destroyed on site and is not a fuel input for energy generation or use (those emissions are monitored and reported under Subpart C of this part), you must estimate the CO2 emissions using Equation FF-8 of this section.