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**MEMORANDUM** FROM: Akachi Imegwu, U.S. EPA, Climate Change Division TO: Docket EPA
- HQ - OAR - 2011 - 0147 DATE: August 3 , 2012 SUBJECT: Summary

of comments on S ubpart W of the final Mandatory Reporting of Greenhouse Gases Rule (40 CFR Part 98) after promulgation that are addressed in the final rule action: 2012 Technical Corrections, Clarifying and Other Amendments to the Greenhouse Gas Reporting Rule, and Confidentiality Determinations for Certain Data Elements of the Fluorinated Gas Source Category **1.0 INTRODUCTION**  The 2010 final rule for Subpart W of the Greenhouse Gas Reporting Rule (Subpart W) was signed b y EPA Administrator Lisa Jackson on November 8, 2010 and published in the Federal Register on November 30, 2010 (75 FR 74458). The 2010 final rule, which became effective on December 31, 2010, included reporting of GHGs from facilities containing petroleum and natural gas sy stems. The rule does not require control of GHGs, rather it only requires that facilities containing petroleum and natural gas s ys tems with emissions sources above certain threshold levels monitor and report emissions and other related data. Since promulgation of the final rule in November 2010, EPA proposed the “ Technical Corrections, Clarifying and Other Amendments to Certain Provisions of the Mandatory Greenhouse Gas Reporting Rule ” on August 4, 2011 ( 76 FR 47392 ) and the “Technical Revisions and Clarifications to Subpart A, Subpart I, and Subpart W” on September 9, 2011 ( 76 FR 56010 )
. Stakeholders were given the opportunity to comment on these proposed rules
. As a result of those comments, EPA made technical and editorial revisions to specific provisions in Subpart W that were finalized on December 23, 2011 (76 FR 80554)
. In addition, the Administrator has identified within Subpart W a number of technical issues that need to be revised and specific provisions that need to be clarified. The purpose of this memorandum is to summarize specific comments r eceived from hotline questions or meetings with affected industry members , and outline the issues being addressed b y the se final amendments. **2 .0**  **SUMMARY OF COMMENT**  **S ADDRESSED BY**  **FINAL AMENDMENTS**  EPA received questions related to implementation of the December 23, 2011 final rule through the EPA Hotline and through meetings with affected industry members. S everal questions have resulted in amendments to specific provisions in S ubpart W in order to provide more clarity and to correct errors
. The EPA has also held meetings with several trade associations representing industries affected b y Part 98, and many questions were presented b y those trade associations that would be resolved through the amendments to S ubp art W.2

For a summary

of the submitted comment s which are being addressed b y technical revisions to S ubpart W , please see the following table , “ Summary of Comments Being Resolved By Technical Corrections, Clarifying and Other Amendments .” All identifying information from the incoming questions has been removed from the table. **Technical Issue Questions Submitted to EPA**  **Type and approximate**  **number of submittals**  **Reference**
**1. Am**  **end Equation W**  **- 6**  **in 98.233(e)(5) by removing a**  **factor of 1000 to leave the**  **calculated emissions in**  **cubic feet rather than**  **convert it to Mcf**  **Question:** This question relates to Subpart W,

equation W
- 6 for desiccant dehydrators. Based on the units of the equation variables, the resulting units for the equation should be Mcf/year (thousand cubic feet per year). However, the rule states that the resulting units are "Es,n = Annual natural gas emissions at standard conditions in cub ic feet." I.e., cf/year (cubic feet per year). Please address this error. At least 1 individual Helpdesk

submission

**2. Am**  **end 98.233(g)(1) to**  **voluntarily allow**  **reporters to take more**  **than the prescribed**  **number of sample**  **measurements per sub**  **- basin**  **and well t ype**  **by inserting the phrase “at**  **least” in the rule text.**  **Question:** 98.233(g)(1) prescribes a graduated

number of measurements or calculations per sub
basin and well type (horizontal or vertical) depending on the total number of completions or workovers
- with the maximum required measurements or calculations prescribed as 5. Would it be acceptable for a company to record the data necessary for the calculations or take a measurement for each completion/workover within a given sub
basin well type combination (e.g. have greater than 5 measurements or calculations). [w hich would result in more accurate reporting of emissions] If so, would the data from each event be used in the emissions estimation or would the company be required to select only the specified number of values for emission estimation purposes? At least 1 indiv idual Helpdesk

submission

**3. Revise**  **Equation W**   ** 15 to clarify** **that “Count” refers to those**  **separators or wells that feed**  **Question:** Equation W
- 15. This equation does not

differentiate between high pressure and low pressure separ ators and whether or not a separator feeds directly to a storage tank or to an additional separator. Do you need to count all separators or only those that feed liquids to a tank at atmospheric pressure (where gas can flash)? It seems that Equation W
- 15 wo uld be more accurate if the definition of 'Count' were changed to 'Total At least 1 individual Helpdesk

submission3

**oil directly to storage tanks.**  number of separators dumping liquids to storage

tanks and wells with throughput less than 10 barrels per day.' This would prevent over
- counting of emissions that do not flash from sep arators feeding to other separators. **4. Revise**  **Equation W**   ** 36 to revise** **the definition of parameter**  **“ρ i**  **” to amend the density**  **value of CH 4**  **to be 0.0192 kg/ft** **3** There appears to be an error in the CH4 density

defined for Equation W
- 36 in 40 CFR 98 Subpart W of the 12/2/11 pre
-publication version of the final rule. I think it should be 0.0191 kg CH4/ft^3 at 60°F and 14.7 psia, while the 12/2/11 version of the rule shows 0.0422 kg CH4/ft^3 at 60°F and 14.7 psia. It appears that EPA forgot to convert the density from units of lb/ft^3 to kg/ft^3. Using the incorrect value in the rule misestimates CH4 emissions by 2.2 times too high. Do you plan to correct this in the rule? If so, when will you do that? If not, may I use the correct CH4 density at 60°F and 14.7 psia (0.0191 kg CH4/ft^3) instead of the value of 0.0422 kg CH4/ft^3 at 60°F and 14.7 psia that is in the 12/2/11 version of the rule? For background, my CH4, CO2 , and N2O density calculations are provided below
. Thanks for your help. Ideal gas law: PV = nRT, or PV = (m/MWT) RT For CH4: (14.7 psia) x (V ft^3) = (m lb/16 lb/lbmole) x (10.73 psia
- ft^3/lbmole
- °R) x (60°F+459.67°R) m/v = CH4 density = 0.0422 lb/ft^ 3 = 0.0191 kg/ft^3 (compared to 0.0422 kg/ft^3 in Equation W
- 36 of the 12/2/11 pre
-publication version of Subpart W) For CO2 and N2O: (14.7 psia) x (V ft^3) = (m lb/44 lb/lbmole) x (10.73 psia
- ft^3/lbmole
- °R) x (60°F+459.67°R) m/v = CO2, N2O density = 0 .1160 lb/ft^3 = 0.0526 kg/ft^3 (compared to 0.0526 kg/ft^3 in Equation W
36 of the 12/2/11 pre
-publication version of Subpart W) At least 1 individual Helpdesk

Submission

**5. Revise**  **Equation W**   ** 39A to replace** **the parameter “ECO2” with**  **“Ea,CO2”. Question:**  [The questioner] was reviewing the GHG

reporting rules (40 CFR Part 98), and found a few minor errors. §98.233(z)(2)(iii) definitions for Eq. W
- 39A and W
39B: change "ECO2" to "Ea,CO2" {variable in equation and definition should match}. At least 1 individual Helpdesk

submission

**6. Revise**  **98.236(c)(9) by removing the**  **text, “using optical gas**  **imaging instrument**  **per 98.234(a)(refer**  **to §98.233(k)), Question:**  The rule is not clear with respect to

98.234(a)(5)
- Does an acous tic leak detection device have to be used to detect through
- valve leakage or are any of the options in 98.234(a)(1
- 5) acceptable for making such determinations? **Response:** Acoustic leak detection devices can specifically be used for through
- valve leakage. However, as per the opening paragraph in 98.234(a), any methods listed under 98.234(a) can be used to determine through
- valve leakages. At least 1 individual Helpdesk

submission4

**or acoustic leak detections**  **of” 7.**  **Revise 98.236.c15(ii)(**  **A), by removing**  **(a)(8) from the list of source**  **categories Question**  : In 98.236.c15.ii.A, EPA added (a)(8) to

the list of source categories but did not add the corresponding Table W
- 7 with distribution emission factors. Why did EPA add distribution to the list and not add the table? NMGC asked this question in October 24, 2011 comments but we do not see a response to this comment in the response to comments. **Response** : EPA agrees that 98.236 (c)(15)(ii)(A) should be updated to reflect the correct citations. EPA has updated the citation and removed the reference to the natural gas distribution table, W - 7 , and industry segment definition (a)(8). At least 1 individual Helpdesk

submission

**8. Update Table**  **W -**  **1A to reflect updates**  **to Population Emission**  **Factors Question:**  I am writing to request confirmati on of

the emission factors published in the "Federal Register /Vol. 76, No. 247 / Friday, December 23, 2011 /Rules and Regulations, TABLE A
- 1A OF SUBPART W - DEFAULT WHOLE GAS EMISSION FACTORS FOR ONSHORE PETROLEUM AND NATURAL GAS PRODUCTION, pages 80591 and 80592. Specifically, the emission factors published in the table for "Eastern US
- Population Emission Factors, All Components
- Gas Service" and "Western US
- Population Emission Factors, All Components
- Gas Service" for valves, connectors, open
- ended lines, and pressure relief valves, have increased by almost 24 times the emission factors published in the previous versions of the rule ("Federal Register / Vol. 75, No. 229 / Tuesday, November 30, 2010, page 74512"). For example: TABLE A - 1A

OF SUBPART W - DEFAULT WHOLE GAS EMISSION FACTORS FOR ONSHORE PETROLEUM AND NATURAL GAS PRODUCTION - Western US (scf/hour/component) Valves: Federal Register, November 30th, 2010
- 0.123 scf/hr/component Federal Register, December 23rd, 2011
- 2.90 scf/hr/component Connector : Federal Register, November 30th, 2010
- 0.017 scf/hr/component Federal Register, December 23rd, 2011
- 0.396 scf/hr/component Open - ended line: Federal Register, November 30th, 2010
- 0.032 scf/hr/component Federal Register, December 23rd, 2011
- 0.748 At least 1 individual Helpdesk

submission5 scf/hr/component Please provide a basis or explanation for this large increase in the emission factor. I was not able to locate an explanation for this change in the Technical Support Documentation or Response to Comments **Response:** Thank you for pointing out the issue with the emission factors listed in Table W
- 1A. **3 .0**  **SUMMARY OF ISSUES FROM INTERNAL REVIEW LINKED TO**  **FINAL AMENDMENTS**  As mentioned above, not all of the corrections and other amendments correspond directly to questions that were raised by reporters. The need for some corrections and other amendments were identified as a result of internal EPA review. The following is a list of the issues being raised from EPA’s review of Subpart W of Part 98 . These issues are listed in the final rule “ 2012 Technical Corrections, Clarifying and Other Amendments to the Greenhouse Gas Reporting Rule, and C onfidentiality Determinations for Certain Data Elements of the Fluorinated Gas Source Category .” **Summary of Issues f** 

**rom Internal Review Being Addressed by Final**  **Amendments** Not all corrections and other amendments correspond directly to questions that were raised b y reporters. The need for some corrections and other amendments were identified as a result of internal EPA review. Below is a summary of the issues that have been raised from the EPA’s review of Subpart W of Part 98
. **Changes to 98.233**  Amend Equation W
- 7 b y changing the parameter FR p to FR and clarifying that T p is cumulative amount of time in hours for venting.  Amend Equation W
- 8 by revising the definition of parameter SP p to clarify that it is a ratio of casing to tubing pressure.  Amend Equation W
- 9 by clarifying calculation methodology 3 applies to well venting not “each” well revising the definition of parameter W to clarify that it is the number of wells with plunger lift assist.  Amend Equations W
- 8 and W
- 9 by replacing the subscript “q” with “p” in SFR to match the definition of SFR p and clarifying terms Vp and HR p,q are to be monitored per unloading event.  Clarify

that appropriate volumetric parameters in Equation W
- 10A, namely F RM s , PR s,p , EnF s,p , and SG s,p , are at standard conditions by adding the subsc ript s
.  Clarify

that Equation W
- 10B parameter FV s,p and EnF s,p are at standard conditions by adding the subscript s
.  Amend section 98.233 (f) by changing the word “backflow ” with “ flowback” .6

 Amend 98.233(f)(1) to voluntarily allow for reporters to take more than prescribed number of samples b y inserting the phrase “at least” in the rule text.  Amend Equation W
- 11A and W
- 11B to insert the word “actual” in the definition of FR and add subscript “a”. Clarify the definition of “A” to state “Cross sectional open area of the restriction orifice (m2 )”.  Clarify

Equation W
- 12 that the relevant volumetric parameters, namel y FRM s , FR s,p , and PR s,p , are at standard conditions. Adding a reference to 98.233 (t) in FRs,p to convert FRa to standard conditions. Renaming the parameter W to N and changed its definition to make it applicable to each measured or calculated well completion or workovers.  Clarify

Equation W
- 13 that the output of the equation is the sum of emissions from all completions and workers without hydraulic fracturing within a sub
- basin by removing the word “a” in front of “gas well venting”.  Amend parameter E s,N to E s,n in Equations W
- 14A .  Revised T a to T a,p in Equation W
- 14B signifying that it is for each blowdown “p”
.  Revise 98.233(j)(5) paragraph description language to clarify that the 10 barrels per day floor is the annual average daily throughput.  Revise Equation W
- 15 to clarify the description of 1000.  Revise Equation W
- 17B to revise the definition of PR to clarify actual and not standard conditions.  Remove and reserve 98.233(n)(7) to harmonize language with reporting requirements in 98.236 and remove an undesired calculation.  Remove the summation operator in Equation W
- 23 and W
- 27 .  Amend Equation W
- 23 and W
- 27 E s,i to E s,i,m to signify that the emission are calculated for each mode
- source combination
. The parameter definition for E s,i,m has also been adjusted to reflect this change.  Added limits to the summation operator in Equation W
- 24 and Equation W
- 28.  Revise Equation W
- 25 to revise the definition of parameter EF i by deleting the term “thousand”.  Amend reference to Table 1
- A to Tabl e W - 1A in paragraph 98.233 (r)(2).  Revise 98.233 (r)(6)(ii) to revise the term “meter or regulator” with “meter/regulator”.  Revise 98.233(t) to clarify that results need not be converted to standard conditions if they already reflect standard conditions.  Revise 98.233 (t)(1) to clarify that emissions or the results of Equation W
- 11A and Equation W
- 11B need to be converted to standard conditions.  Revise parameter definition for E s,n in Equation W
- 33 to clarify that FR s,p is E s,n when calculating subsonic or sonic flowrates under 98.233(g)
. Revise parameter for E a,n to clarify that FRa,p is E a,n when calculating subsonic and sonic flowrates under 98.233(g).  Revise 9 8.23 3(z)(2)(vi) to reflect the correct means of referring to HHV. **Changes to 98.236**  Amend 98.236 (c)(5)(ii)(D) by making it the average internal casing diameter for all wells instead of each well.  Amend 98.236 (c)(13) (i)(G), (ii)(C), (iii)(C) , (iv), and (v)(B) by correcting the units to metric tons CO 2 e for each gas.7

 Amend 98.236 (c)(14) (i )(C), (ii)(C), (iii)(C), (iv), and (v)(B) b y correcting the units to metric tons CO 2 e for each gas.  Amend 98.236(c)(15)(i)(B) b y updating the incorrect reference to Equation W
- 30 to read Equation W
- 30A.  Amend 98.236(c)(15)(i)(C) by updating the incorrect reference to Equation W
- 30 to read Equation W
- 30A and by

deleting the unnecessary reference to parameter GHG i .  Amend 98.236(c)(15)(ii)(A) b y deleting the reference to 98.230 (a)(4) and Table W
- 3.  Amend 98.236(c)(17)(v) by removing CH 4 and make the reporting requirement only applicable to CO 2 emissions. **Changes to Emission Factor Tables**   Revise the incorrect title of Table W
- 1A of subpart W by deleting “TABLE A
- 1A” and updating it to “TABLE W
- 1A”.  Revise the pneumatic device emission factors for the Western U.S. in Table W
- 1A to reflect the same changes that were made to pneumatic device emission factors in the Eastern U.S.  Amend Table W
- 5 to provide the cross
- reference for footnote 2 b y adding the reference to Vapor Recovery

Compressor.