This page provides an overview of the blowdown vent stacks source type reporting requirements for Subpart W.
Please see Reporting Form Instructions on downloading the blank reporting form and uploading the completed reporting form.
You may also refer to Optional Calculation Spreadsheet Instructions to download the Subpart W calculation spreadsheet.
The blowdown vent stacks source type is applicable to Onshore natural gas processing (98.236(a)(3)), Onshore natural gas transmission compression (98.236(a)(4)), LNG import and export equipment (98.236(a)(7)), Onshore petroleum and natural gas gathering and boosting (98.236(a)(9)), and Onshore natural gas transmission pipeline (98.236(a)(10)).
For facilities with blowdown vent stacks subject to reporting, Table I.1 must be completed. For blowdown vent stack emissions calculated by equipment or event type, Table I.2 must be completed. For blowdown vent stack emissions calculated by flow meter, Table I.3 must be completed. If emissions from some blowdown vent stack emissions were calculated using flow meters, and emissions from other blowdown vent stacks were calculated by equipment or event type, then both Tables I.2 and I.3 must be completed. For Onshore natural gas transmission pipeline facilities, Table I.4 must be completed. Table I.5 is required for the identification of missing data procedures used for blowdown vent stack emission calculations.
Indicate if the facility has the source type via the radio buttons.
If the source type is present you must report required elements.
If the facility has the source type, then indicate whether missing data procedures were used.
Reporting Requirements
Table I.1 Blowdown Vent Stacks Emissions Type must be completed by all facilities subject to 98.236(i) reporting.
- How were emissions determined? [98.236(i)]
- Calculated by equipment or event type
- Using flow meters
- Combination of flow meters and calculating by equipment or event type
Table I.2 Blowdown Vent Stacks Emissions Calculated by Equipment or Event type must be completed for blowdown emissions assessed by equipment or event type. Required data elements include:
- Equipment or event type [98.236(i)(1)],[98.236(i)(2)]. Note that there are 2 columns for this data element. Onshore natural gas transmission pipeline facilities use only the second column, and facilities in other segments use only the first column.
Total number of blowdowns for equipment or event type [98.236(i)(1)(i)]
Annual total CO2 emissions for each equipment or event type [98.236(i)(1)(ii)]
Annual total CH4 emissions for each equipment or event type [98.236(i)(1)(iii)]
Table I.2 Blowdown Vent Stacks Emissions Calculated by Equipment or Event type
Table I.3 Blowdown Vent Stacks Emissions Calculated using flow meters must be completed for blowdown emissions assessed using flow meters:
Annual total CO2 emissions calculated by flow meter [98.236(i)(2)(i)]
Annual total CH4 emissions calculated by flow meter [98.236(i)(2)(ii)]
Table I.3 Blowdown Vent Stacks Emissions Calculated using flow meters
Table I.4 Onshore natural gas transmission pipeline characterization must be completed only by Onshore natural gas transmission pipeline facilities. Please report the following:
- U.S. State [98.236(i)(3)]
Annual total CO2 emissions [98.236(i)(3)(i)]
Annual total CH4 emissions [98.236(i)(3)(ii)]
Annual number of blowdown events [98.236I(i)(3)(iii)]
Table I.4 Onshore natural gas transmission pipeline characterization
Table I.5 Missing data procedures used for Blowdown Vent Stacks emission calculations
If your facility relied on missing data procedures to develop your reporting for blowdown vent stacks please provide the following:
- Compliance Method
Type (for facilities other than Onshore natural gas transmission pipelines)
Type (for Onshore natural gas transmission pipeline)
Parameters
- Measurement Frequency
Number of quarters missing data procedures were used [98.236(bb)(1)] (required only if the measurement frequency was quarterly)
Total number of hours in the year missing data procedure was used [98.3(c)(8)], [98.236(bb)(2)] (required unless the measurement frequency was quarterly, annually, biannually, or N/A)
Procedures used for missing data [98.235(h)]
Table I.5 Missing data procedures used for Blowdown Vent Stacks emission calculations
Total Emissions
The total emissions roll-up at the top of the sheet reflects the sum of each gas emission reported for the source type. These summations are calculated automatically by the Smart Form and tabulated on the Introduction tab.
