Document KJdpJMnZQLVrnOy13Lx9xKd4N

Areas of Concern 1. The EPA detected hydrocarbon emissions from the storage tanks at well pads co-located with the following wells: x Liberty LR 14-23H x Clarks Creek 41-0805H 2. The EPA detected hydrocarbon emissions from an unlit flare co-located with the following wells or compressor sites: x Parshall 16-32H x Liberty 103-13H x Liberty LR 14-23H x Liberty CDP Compressor Site (Pecan Pipeline) x Liberty LR 12-11H x Liberty 8-01H x Clarks Creek SEC 7 SES 6 OPF Compressor Site x Parshall 28-2928H 3. The EPA detected unburned hydrocarbon (UBHC) emissions from operating utility flares colocated with the following wells: x Vanhook 47-3626H x Parshall 11-28H 4. The EPA detected visible emissions from operating utility flares co-located with the following wells: x Liberty LR 47-1416H x Liberty 106-0107H See Table 1 below for more details regarding inspected locations and Tables 2 and 3 for inspection observation details for all pads. A log of images and videos captured during the inspections is provided in Appendix A. General Inspection Information Unannounced well pad inspections were conducted jointly by U.S. EPA and Fort Berthold Indian Reservation (FBIR) Tribal inspectors on November 5-8, 2023, at multiple EOG facilities located on the FBIR. The EPA evaluated each EOG well site listed in Table 1 using audio, visual, and olfactory (AVO) inspection methods including the use of an optical gas imaging (OGI) camera and EPA Reference Method 22. At each facility, inspectors scanned the crude and/or water storage tanks, closed vent system and flares onsite for any detectable emissions. Specifically, inspectors scanned storage tank covers and closed vent systems for hydrocarbon emissions to determine compliance with the Clean Air Act, including the Fort Berthold FIP and NSPS OOOOa. Each well pad inspection followed the approach below: 1. Record the entry sign of the well pad when available. Survey the entire well pad with OGI camera. Page 2 of 9 Observations and Regulatory Applicability Fort Berthold FIP and NSPS OOOOa regulations which are potentially relevant to the Areas of Concern observed during inspections are summarized in this section. Tables 2 and 3 at the end of this report summarize inspection observations and findings. Table 2 includes well head counts and storage tank observations. Table 3 includes details of control devices and related observations. See Appendix A for a log of images and videos taken during the inspections. Fort Berthold FIP Applicability Based on drilling information reported to the NDIC well index by EOG, the facilities listed in Table 1 were completed after the August 12, 2007, applicability date (per 40 C.F.R. 49.4161) and are producing from the Bakken Pool (per 40 C.F.R. 49.4163(a)(1)) and are thus subject to the Fort Berthold FIP. Closed Vent System Equipment Requirements [ 49.4165(b)] Per 49.4165(b)(1), "Each closed-vent system must route all produced natural gas and natural gas emissions from production and storage operations to the natural gas sales pipeline or the control devices..." The EPA, using an OGI camera, detected natural gas emissions from production and storage tanks at two out of twenty-five facilities evaluated. See Area of Concern #1 above. Utility Flare Requirements [ 49.4165(c)] Per 49.4165(c)(6)(vi), "The owner or operators must ensure that each enclosed combustor and utility flare is maintained in a leak-free condition." The EPA, using an OGI camera, detected emissions from an unlit flare at eight out of twenty-five facilities evaluated. See Area of Concern #2 above. Per 49.4165(c)(1), "For each enclosed combustor or utility flare, the owner or operator must follow the manufacturer's written operating instructions, procedures and maintenance schedule to ensure good air pollution control practices for minimizing emissions." The EPA noted UBHC emissions indicating poor air pollution control practices from lit flares at two out of twenty-five facilities evaluated. See Area of Concern #3 above. Per 49.4165(c)(6)(vii), "The owner or operator must ensure that each enclosed combustor and utility flare is operated with no visible smoke emissions." Per 49.4166(g)(3) and EPA Reference Method 22, the EPA noted black smoke emissions at two out of twenty-five facilities evaluated. See Area of Concern #4 above. NSPS OOOOa Applicability Based on well production information reported by EOG to the NDIC and the date of construction, reconstruction, or modification of the storage vessels, the EPA believes that storage vessels and associated emissions control equipment at fifteen of the twenty-five oil and natural gas production facilities identified in Table 1 are subject to requirements for storage vessel affected facilities in NSPS OOOOa: x Riverview 26-3031H x Hawkeye 100-2501H x Fertile 50-0509H x Liberty LR 53-1416H x Liberty LR 47-1416H x Liberty LR 107-1109H Page 4 of 9 x Liberty LR 12-11H x Liberty 106-0107H x Van Hook 47-3626H x Clarks Creek 41-0805H x Clarks Creek 65-07H x Clarks Creek SEC 7 SES 6 OPF x Parshall 78-20H x Parshall 28-2928H x Parshall 86-29H Closed Vent System Equipment Requirements [ 60.5411a(c)] Per 60.5411a(c)(1), owners and operators must "Design the closed vent system to route all gases, vapors, and fumes emitted from the material in the storage vessel to a control device that meets the requirements specified in 60.5412(c) and (d), or to a process." The EPA, using an OGI camera, observed emissions from the closed vent system at the Clarks Creek 41-0805H facility. See Area of Concern #1 above. Control Device Requirements [ 60.5412a(d) and 60.5413a(e)] Per 60.5412a(d)(1)(ii), owners and operators must, for each combustion control device, "install and operate a continuous burning pilot flame." The EPA observed unlit pilot flames at the Liberty LR 1211H, Clarks Creek SEC 7 SES 6 OPF Compressor Site, and Parshall 28-2928H facilities. See Area of Concern #2 above. Per 60.5413(a)(e)(8), owners and operators must, "Operate each control device following the manufacturer's written operating instructions, procedures and maintenance schedules to ensure good air pollution control practices for minimizing emissions." The EPA noted UBHC emissions indicating poor air pollution control practices from a lit flare at the Vanhook 47-3626H facility. See Area of Concern #3 above. Per 60.5412a(d)(1)(iii), owners and operators must, "Operate the combustion control device with no visible emissions, except for periods not to exceed a total of 1 minute during any 15-minute period." The EPA observed black smoke continuously for more than five minutes (per Method 22) at the Liberty LR 47-1416H and Liberty 106-0107H facilities. See Area of Concern #4 above. Page 5 of 9 Liberty 106- 1 0107H Van Hook 1 47-3626H Liberty 8- 1 01H Van Hook 1 13-35H Clarks 3 Creek 41- 0805H Clarks 1 Creek 65- 07H Clarks 2 Creek SEC 7 SES6 OPF Clarks 1 Creek 10- 0805H Parshall 78- 1 20H Parshall 28- 1 2928H HC-AA Yes Yes None HC-AA Yes Yes HC-AA No No HC-AA Yes No HC, Yes, No, HP 2-prong, Yes, No, AA Yes No AA Yes No AA, No, No, HC No No None None None None None None HC Yes Yes None HC Yes No None HC No No None Parshall 86- 1 HC 29H Yes No None Continuous visible emissions for >5 minute per Method 22. Unburned hydrocarbon from the flare detected by OGI camera. Continuous emission from unlit flare. None None MOV_3372 MOV.3373 None None None Downward Downward Odor detected onsite Downward Downward Downward None Continuous emissions from unlit HighCapacity flare and Air Assist. None MOV 3423, MOV_3424 None Continuous emissions from unlit flare. Due to extremely high wind speeds, OGI video may not show the full extent of the venting. Odor was detected. None MOV_3435, DC_3437, DC_3438 Downward Downward Downward Inspectors discussed unlit flares with EOG operator while on site Downward Downward In the control panel, "pilot failure" alarm message was in red. Downward Page 8 of 9 Parshall 11- 1 HC 28H Parshall 67- 1 HC 2117H Parshall 82- 1 HC 2827H Yes No None Yes No Yes No None None Continuous unburned hydrocarbon trail. Pilot is lit but the gas is not being combusted in flame. Odor was detected on site. None MOV_3441 None Upward Downward Downward Page 9 of 9 DSCN0033.JPG, DSCN0034.JPG, DSCN0035.JPG, DSCN0036.JPG DC_3365.JPG, MOV_3366.MP4 MOV_3367.MP4 MOV_3369.MP4 MOV_3370.MP4 MOV_3371.MP4 MOV_3372.MP4 MOV.3373.MP4 MOV 3423.MP4, MOV_3424.MP4 MOV_3435.MP4, DC_3437.JPG, DC_3438.JPG MOV_3441.MP4 Improper slope to the K/O drum. HAWKEYE 100-2501H Continuous emission from unlit flare. Continuous emission from unlit flare. Continuous emission from unlit flare (HC-2 prong). Continuous emission from unlit flare. Continuous emissions from unlit flare. Unburned HC from the flare detected. Continuous emission from unlit flare. Continuous emissions from unlit HC flare and Air Assist. Continuous emissions from unlit flare. Due to extremely high wind speeds, OGI video may not show the full extent of the venting. Continuous unburned hydrocarbon trail. Pilot is lit but the gas is not being combusted in flame. Parshall 16-32H Liberty 103-13H Liberty LR 14-23H Liberty CDP Compressor Site Liberty LR 12-11H Van Hook 47-3626H Liberty 8-01H Clarks Creek SEC 7 SES6 OPF Parshall 28-2928H Parshall 11-28H Page 2 of 2