Document ID: EPA-HQ-OAR-2011-0147-0041
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2012-05-14T04:00Z

MEMORANDUM

FROM:	Akachi Imegwu, U.S. EPA, Climate Change Division

TO:	Docket EPA-HQ-OAR-2011-0147

DATE:		 May 7, 2012

SUBJECT:	Summary of comments on Subpart W of the final Mandatory 
            Reporting of Greenhouse Gases Rule (40 CFR Part 98) after promulgation that are addressed in the proposed rule action: 2012 Technical Corrections, Clarifying and Other Amendments to the Greenhouse Gas Reporting Rule, and Proposed Confidentiality Determinations for Certain Data Elements of the Fluorinated Gas Source Category
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1.0	INTRODUCTION
      
      The 2010 final rule for Subpart W of the Greenhouse Gas Reporting Rule (Subpart W) was signed by 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 systems.  The rule does not require control of GHGs, rather it only requires that facilities containing petroleum and natural gas systems 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 received from hotline questions or meetings with affected industry members, and outline the issues being addressed by these proposed amendments. 

2.0	SUMMARY OF COMMENTS ADDRESSED BY PROPOSED 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.   Several questions have resulted in amendments to specific provisions in Subpart W in order to provide more clarity and to correct errors. The EPA has also held meetings with several trade associations representing industries affected by Part 98, and many questions were presented by those trade associations that would be resolved through the amendments to Subpart W.
       For a summary of the submitted comments which are being addressed by technical revisions to Subpart 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.    Amend 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 cubic feet." I.e., cf/year (cubic feet per year). 

Please address this error.
At least 1 individual
Helpdesk submission
   2.    Amend 98.233(g)(1) to voluntarily allow reporters to take more than the prescribed number of sample measurements per sub-basin and well type 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). [which 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 individual
Helpdesk submission
   3.    Revise Equation W-15 to clarify that "Count" refers to those separators or wells that feed oil directly to storage tanks.
Question:  Equation W-15. This equation does not differentiate between high pressure and low pressure separators 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 would be more accurate if the definition of 'Count' were changed to 'Total 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 separators feeding to other separators.
At least 1 individual
Helpdesk submission
   4.    Revise Equation W-36 to revise the definition of parameter "ρi" to amend the density value of CH4 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)), or acoustic leak detections of"
Question: The rule is not clear with respect to 98.234(a)(5) - Does an acoustic 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 submission
   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 W-7 should be referenced in 98.236 (c)(15)(ii)(A), and has taken note of this. Thank you for alerting EPA to this issue; we are considering options to address this.
At least 1 individual
Helpdesk submission
   8.    Update Table W-1A to reflect updates to Population Emission Factors 
Question:  I am writing to request confirmation 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 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.
At least 1 individual
Helpdesk submission

3.0	SUMMARY OF ISSUES FROM INTERNAL REVIEW LINKED TO PROPOSED 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 proposed rule " 2012 Technical Corrections, Clarifying and Other Amendments to the Greenhouse Gas Reporting Rule, and Proposed confidentiality Determinations for Certain Data Elements of the Fluorinated Gas Source Category."

Summary of Issues from Internal Review Being Addressed by Proposed Amendments

Not all 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.  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 by changing the parameter FRp to FR and clarifying that Tp is cumulative amount of time in hours for venting.
   * Amend Equation W-8 by revising the definition of parameter SPp to clarify that it is a ratio of casing to tubing pressure.
   * Amend Equation W-9 by 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 SFRp and clarifying terms Vp and HRp,q are to be monitored per unloading event.
   * Clarify that appropriate volumetric parameters in Equation W-10A, namely FRMs, PRs,p, EnFs,p, and SGs,p, are at standard conditions.
   * Clarify that Equation W-10B parameter FVs,p and EnFs,p are at standard conditions. 
   * Amend 98.233(f)(1) to voluntarily allow for reporters to take more than prescribed number of samples by 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 (m[2])".
   * Clarify Equation W-12 that the relevant volumetric parameters, namely FRMs, FRs,p, and PRs,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 Es,N to Es,n in Equations W-14A and revised Ta to Ta,p in Equation W-14B.
   * 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.
   * Added limits to the summation operator in Equation W-24 and Equation W-28. 
   * Revise Equation W-25 to revise the definition of parameter EFi by deleting the term "thousand".
   * Amend reference to Table 1-A to Table 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 [9]8.233(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)(iii)(C) by correcting the units to metric tons CO2e for each gas.
   * Amend 98.236(c)(15)(i)(B) by 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.  
   * Amend 98.236(c)(15)(i)(C), EPA by deleting the unnecessary reference to parameter GHGi.
   * Amend 98.236(c)(17)(v) by removing CH4 and make the reporting requirement only applicable to CO2 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 emission factors in Table W-1A to reflect standard temperature and pressure using the correct version from the November 2010 rule and to reflect Population Emission Factors for Western U.S.
   * 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 by adding the reference to Vapor Recovery Compressor.