Document GzZr0ZEv9EQGR6qmyd7JE93Jv

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY OFFICE OF ENFORCMENT AND COMPLIANCE ASSURANCE DATE: SUBJECT: FROM: THRU: TO: See date of Section Chief signature CLEAN AIR ACT INSPECTION REPORT Waste Management Atascocita Landfill, Humble, TX Daniel Heins, Environmental Scientist Stationary Source Enforcement Branch, EPA OECA Gregory Fried, Branch Chief Stationary Source Enforcement Branch, EPA OECA File BASIC INFORMATION Facility Name: Waste Management Atascocita Landfill Facility Location: 3623 Wilson Road, Humble, TX 77396 Date of Inspection: On Site Inspection: March 15, 2023 Virtual Conference: April 25, 2023 EPA Inspector(s): 1. Daniel Heins, Environmental Scientist, EPA OECA a,b 2. Daniel Hoyt, Environmental Engineer, EPA OECA a,b 3. Colleen McCarthy, Air Inspector, EPA Region 6 a,b 4. Kenneth McPherson, Life Scientist, EPA Region 6 b 5. Benjamin Rosenthal, Air Inspector, EPA Region 6 a,b Other Attendees: 1. Keith Sharon, Area Gas Operations Manager for TX/OK, WM a,b 2. Heather Lehrmann, Director of Environmental Protection & Compliance for TX/OK, WM a,b 3. Dave Thorley, Director of Air Compliance, WM a,b 4. Joseph Tommaso, Gas Operations Supervisor, WM a,b 5. Andrew Berry, Environmental Compliance Manager, WM a 6. Justin Posey, Environmental Specialist, WM a,b a Attended conference b Attended surface emissions monitoring (SEM) Page 1 of 17 Contact Email Address: ksharon@wm.com Purpose of Inspection: Surface monitoring and partial compliance evaluation for the Clean Air Act Facility Type: Muncipal solid waste (MSW) landfill Regulations Central to Inspection: 40 C.F.R. Part 60, Subpart WWW; 40 C.F.R. Part 62, Subpart OOO; 40 C.F.R. Part 63, Subpart AAAA; 40 C.F.R. Part 98, Subpart HH On Site (3/15) Arrival Time: 09:00 Central On Site (3/15) Departure Time: 17:00 Central Virtual Conference (4/25) Start Time: 14:30 Central Virtual Conference (4/25) End Time: 16:00 Central Inspection Type: Unannounced Inspection Announced Inspection SITE OVERVIEW The following information was obtained verbally from Waste Management representatives during the virtual conference. Company Ownership: Waste Management's Atascocita Landfill ("the Landfill") is permitted to and owned/operated by WM of Texas, Inc., along with other Texas landfills under Waste Management, Inc. The site has always been operated by Waste Management. Operations Overview: The Landfill began permitting in 1982 and started accepting waste in 1983. Its design capacity is approximately 50.6 million megagrams (Mg). The most recent expansion of its permitted design capacity was in 2010. The site is roughly divided into two areas, the "North Hill" on the northwest side of the site, and the "South Hill" on the southeast side of the site (see Overview Map in Appendix C). The present active area is on the far eastern end of the South Hill, all in areas that have had waste in place for less than five years. None of the Landfill is at final elevation, so the active area may at some times in the past and future be over areas with waste in place for longer than five years. Approximately 306 acres of the site are under intermediate cover, 10 acres under final cover, and 2 under daily cover. Intermediate cover is a minimum of 18 inches of soils. Tarps are approved for daily cover. The Landfill operates 24/7, so soils are added when moving the working face away from an area. Page 2 of 17 The Landfill receives approximately 5000 tons per day of waste, with approximately 20 years of capacity left pending market conditions. Waste includes MSW, construction & demolition (C&D) waste, sludges (primarily wastewater treatment plant), and class 2 and 3 industrial wastes. The Landfill accepts asbestos waste and does not accept potentially refrigerantcontaining appliances. The gas collection and control system presently contains approximately 415 gas collection points. As of 2022, approximately 266 were vertical, 32 were horizontal, and 79 were alternative collectors, including leachate risers with gas collection and collectors outside of the waste mass for migration control. Vertical well construction typically is a 36" borehole drilled into the waste mass with PVC or HDPE pipe with aggregate backfill. Some wells have dewatering pumps. Condensate and leachate are collected separately but comingle in storage tanks from which they are trucked off site for disposal. The Landfill has typically been collecting approximately 5,500 to 6,500 scfm of gas over the past few years. The landfill has three 150 horsepower blowers, typically running two at a time. Gas is routed either to on-site flares or to a renewable natural gas (RNG) plant owned/operated by Montauk Energy. The current flares on site are a 3,200 standard cubic feet per minute (scfm) open flare and a 6,000 scfm open flare. These are being replaced by what will ultimately be an arrangement of four 3,000 scfm low-NOx enclosed flares with one small utility flare. Most gas is routed to the RNG plant. All gas is routed to a common header, some percent of the gas may be routed to flares if the RNG plant cannot take all the gas. The RNG plant typically takes all collected gas, with an approximate capacity of 7,000 - 7,500 scfm. SITE TOUR -- MARCH 15, 2023 Presented Credentials Stated authority and purpose of inspection Provided Small Business Resource Information Sheet Small Business Resource Information Sheet not provided. Reason: Not a small business Asked the company to identify CBI, none identified Data Collected and Observations: EPA conducted an abbreviated SEM survey of the facility. EPA used three ThermoFisher Toxic Vapor Analyzers 2020 (TVA2020) to perform EPA Reference Method 21 for the SEM. EPA monitored in two teams, with the third instrument moving between the two teams to provide confirmation readings for each exceedance point. GPS tracks were recorded for the confirmation instrument. EPA monitored exclusively on the North Hill, an area that had not seen any recent construction or waste deposition activity. In the morning, the survey was focused on the southern slope of the North Hill. In the afternoon, the survey focused on the western north slope of the North Hill. See Appendix C for maps of coverage. Total EPA coverage was less than 40% of the North Hill. Page 3 of 17 The EPA inspectors flagged 75 points above 500 ppm methane. 44 exceedances were at penetrations, 31 exceedances were not in association with penetrations. All but two of the exceedances had confirmation measurements and included measurements within 5 to 10 centimeters of the landfill surface. The two remaining locations were points of intermittent venting of landfill gas from the tops of wells: in one case a sump missing a cover cap, and the other from the pneumatic dewatering pump. The bulk of the exceedances were found at wellheads, areas of erosion, exposed waste, or leachate risers. Multiple exceedances were in bubbling ponded liquids. Some of the leachate risers appeared to be the source of relatively large amounts of leaking landfill gas, with significant odors and high readings measured at multiple feet away from the risers. The exceedances at the risers were all measured within 5-10 cm of the surface in addition to from the risers directly. EPA observed erosion gulleys, leachate breakouts, and exposed waste on the North Hill. WM staff accompanied the EPA inspectors, observed the EPA monitoring, and were given the opportunity to view all EPA readings. EPA asked the WM staff to identify any concerns that they had with any of the EPA monitoring. WM indicated that the exceedances EPA measured from pneumatic pumps or other points on top of the wellheads were not "surface exceedances" subject to monitoring. EPA highlighted that regardless of whether these were subject to SEM requirements, the measurements indicated venting of collected gas that would need correction. WM stated that they believed that the leachate risers were only subject to monitoring at the point where it penetrated the cover. EPA highlighted that the exceedances were detected at those locations as well as from leaking gaskets, and that the quantities of leaking gas appeared significant. Photos and/or Videos: were taken during the inspection. See Appendix A. Field Measurements: were taken during this inspection. See Appendix B. INSPECTION CONFERENCE -- APRIL 25, 2023 Provided U.S. EPA point of contact to the facility Asked the company to identify CBI, none identified EPA showed facility representatives a map of the path walked during the on-site SEM survey and the exceedances detected. Staff Interview: The Landfill operates under Federal Plan Part 62 Subpart OOO, having previously operated under NSPS Part 60 Subpart WWW. It began using NESHAP Part 63 Subpart AAAA requirements on the effective date of Subpart AAAA in September 2021. The Landfill has an uncontrolled non-methane organic compound generation rate of greater than 50 megagrams and has been subject to gas collection and control requirements for longer than the past five years. It is to be determined if there could be potential expansion beyond the current capacity. Storm debris was highlighted as a source of irregular large amounts of waste, with the aftermath of Hurricane Harvey resulting in one year using up airspace that would normally take six years to fill. Page 4 of 17 WM uses Weaver for their emissions estimates and reporting, providing them the waste data to run the calculations. The Landfill has gas migration probes which WM checks quarterly. No probes are currently showing gas at the lower explosive limit. Wellheads are checked monthly, but all additional tuning and monitoring is tracked on a database. Liquid levels in wells are surveyed annually. The decision to install a dewatering pump is based off of well performance and would not necessarily be done just based off the liquids survey results. Gas routed to the RNG plant is supposed to be a minimum of 50% methane. If oxygen was above around 1.5% then Montauk would communicate to WM and technicians would start investigating to see if there are obvious maintenance issues and otherwise retune wells as needed. There is a nitrogen removal unit at the RNG plant. The RNG plant is separately permitted. No wells are currently operating above 145 degrees Fahrenheit. Some alternative collectors have approved positive pressure allowances. H/ET has been conducting the SEM surveys for WM for the past several years, using a SEM5000. They are continuously monitoring with that instrument. When the working face is within the 5-year limit that would be identified as a dangerous area. WM cannot recall identifying any slopes as too steep to safely monitor. WM/HET would not exclude areas from monitoring due to high vegetation. WM has a third party contracted to do routine mowing, if there was high vegetation obstructing monitoring than WM would schedule mowing and monitoring to cover that area. WM has a best management practice/protocol they share with H/ET, and provide them a list of penetrations and a path to walk. Cover integrity surveys are done by site staff monthly, with issues and corrections documented. The site has approximately 35 employees. Page 5 of 17 Reviewed documents: On site: 2022 Q4 SEM Survey Report o Performed by H/ET with a SEM 5000 o 15 total exceedances 12 at penetrations 2 on the South Hill 10 on the North Hill 3 other exceedances (all on the North Hill) Fewer than 5 total exceedances in the approximate area of EPA survey Prior to inspection (available publicly online): November 2022 Semi-Annual Report, including 2022 Q2 & Q3 SEM results o Q2 SEM 67 exceedances total Approximately 37 from the North Hill Fewer than 20 in the approximate area of EPA survey o Q3 SEM 34 exceedances total Approximately 19 from the North Hill Fewer than 12 in the approximate area of EPA survey Via email / for conference: SEM re-monitoring and corrective actions in response to EPA identified exceedances o All penetrations were identified as being corrected with added cover and bentonite seals, five of which required additional soils and or seals Verbally stated during the conference: Regarding the pneumatic pumps that EPA found to be venting landfill gas, WM stated that they redirected the pump exhaust into the system, but stated that they do not do this by default because that would add oxygen to the gas stream. WM stated that some of the leachate risers may have been retuned or had automated collectors added in addition to the bentonite/soils work highlighted in the followup document. o All non-penetration exceedances were identified as being corrected with added cover soils and were less than 500 ppm at the 10-day and 1-month re monitoring Requested documents: After discussing preference between a Section 114 Request For Information Letter and an emailed list of documents associated with the inspection, WM expressed a preference for the latter. Page 6 of 17 Concerns: EPA noted a significant disparity between the number of exceedances they had found compared with recent SEM surveys, indicating possible concerns with the quality of the SEM surveys EPA noted that they observed points of erosion, leachate breakouts, and exposed waste throughout the day EPA noted that the venting of landfill gas from the pneumatic pumps appeared to be a recurring problem EPA noted that the leachate risers particularly seemed to be large sources of leaking landfill gas DIGITAL SIGNATURES _________________________________ Daniel Heins, Lead Inspector PROVIDENC PROVIDENCE SPINA Digitally signed by E SPINA Date: 2023.06.22 17:02:24 -04'00' __________________________________ on behalf of Gregory Fried, Supervisor Page 7 of 17 APPENDICES AND ATTACHMENTS Appendix A: Digital Image Log Appendix B: Field Measurement Appendix C: Maps Page 8 of 17 APPENDIX A: DIGITAL IMAGE LOG Inspector Names: Daniel Heins, Daniel Hoyt, Benjamin Rosenthal Archival Record Location: US EPA SharePoint Image Log (1/3) Image # File Name 1 20230315_162405.jpg 2 IMG_3934.JPG 3 IMG_3935.JPG 4 IMG_3936.JPG 5 IMG_3937.JPG 6 IMG_3938.JPG 7 IMG_3939.JPG 8 IMG_3941.JPG 9 IMG_3942.JPG 10 IMG_3943.JPG 11 IMG_3944.JPG 12 IMG_3945.JPG 13 IMG_3946.JPG 14 IMG_3947.JPG 15 IMG_3948.JPG 16 IMG_3949.JPG 17 IMG_3950.JPG 18 IMG_3952.JPG 19 IMG_3953.JPG 20 IMG_3954.JPG 21 IMG_3955.JPG 22 IMG_3959.JPG 23 IMG_3960.JPG 24 IMG_3961.JPG 25 IMG_3962.JPG 26 IMG_3963.JPG 27 IMG_3964.JPG 28 IMG_3965.JPG 29 IMG_3966.JPG 30 IMG_3967.JPG 31 IMG_3968.JPG 32 IMG_3969.JPG 33 IMG_3970.JPG 34 IMG_3971.JPG 35 IMG_3972.JPG 36 IMG_3973.JPG 37 IMG_3974.JPG 38 IMG_3975.JPG 39 IMG_3976.JPG Date/Time (Central) 2023:03:15 16:24:05 2023:03:15 10:48:27 2023:03:15 10:59:58 2023:03:15 11:12:42 2023:03:15 11:32:33 2023:03:15 11:38:41 2023:03:15 11:44:32 2023:03:15 11:46:12 2023:03:15 11:47:20 2023:03:15 11:49:40 2023:03:15 11:51:42 2023:03:15 11:53:20 2023:03:15 11:53:32 2023:03:15 11:58:07 2023:03:15 12:07:19 2023:03:15 12:09:20 2023:03:15 12:12:17 2023:03:15 12:17:36 2023:03:15 12:17:43 2023:03:15 12:20:45 2023:03:15 12:20:52 2023:03:15 12:26:27 2023:03:15 12:31:21 2023:03:15 12:31:43 2023:03:15 14:38:14 2023:03:15 14:41:56 2023:03:15 14:45:45 2023:03:15 14:45:47 2023:03:15 14:48:36 2023:03:15 14:50:15 2023:03:15 14:54:48 2023:03:15 14:59:11 2023:03:15 14:59:22 2023:03:15 14:59:25 2023:03:15 15:02:48 2023:03:15 15:02:51 2023:03:15 15:04:36 2023:03:15 15:06:51 2023:03:15 15:10:59 Description B30. Landfill gas bubbling through liquids A6. pipe penetrations IV-4/5/6 A7. Bare ground/distressed vegetation A9. Pneumatic pump outlet leaking LFG, H265 A11. Bare patch of earth. A12. GW656. A13. Bare earth and exposed waste A14. Mattresses exposed at GW-656A A14. Mattresses exposed at GW-656A A15. Bare ground. A15. Bare ground. A16. Flagging foam in bare ground. Additional exposed waste and bare ground A17. GW664 A18 Exposed waste/distressed vegetation A19 capped well A20 bare ground A20 erosion/rivulet A20 erosion/rivulet Bubbling leachate breakout Bubbling leachate breakout A22 Erosion gulley A23 venting LFG from taped connector on welhead ATP2-0001 A23 venting LFG from taped connector on welhead ATP2-0001 A27 discolored soils at base of penetration Exposed waste A28 erosion/discolored soils A28 erosion/discolored soils A29 GW338 with erosion gulleys A30 exposed waste and erosion A32 exposed waste A32 exposed waste and bare ground Erosion/exposed waste/bare ground Erosion rivulets and bare ground A33 erosion A33 erosion A34 GW-336-R2 with exposed waste Ponded liquids and discolored soils/distressed vegetation A35 erosion gulleys/bare soil Page 9 of 17 Image Log continued (2/3) Image # File Name 40 IMG_3977.JPG 41 IMG_3978.JPG 42 IMG_3979.JPG 43 IMG_3980.JPG 44 IMG_3981.JPG 45 IMG_3982.JPG 46 IMG_3983.JPG 47 IMG_3984.JPG 48 IMG_3985.JPG 49 IMG_3986.JPG 50 IMG_3987.JPG 51 R0010009.JPG 52 R0010010.JPG 53 R0010011.JPG 54 R0010012.JPG 55 R0010013.JPG 56 R0010014.JPG 57 R0010015.JPG 58 R0010016.JPG 59 R0010017.JPG 60 R0010018.JPG 61 R0010019.JPG 62 R0010020.JPG 63 R0010021.JPG 64 R0010022.JPG 65 R0010023.JPG 66 R0010024.JPG 67 R0010025.JPG 68 R0010026.JPG 69 R0010027.JPG 70 R0010028.JPG 71 R0010029.JPG 72 R0010030.JPG 73 R0010031.JPG 74 R0010032.JPG 75 R0010033.JPG 76 R0010034.JPG 77 R0010035.JPG 78 R0010036.JPG 79 R0010037.JPG 80 R0010039.JPG Date/Time (Central) 2023:03:15 15:15:26 2023:03:15 15:22:18 2023:03:15 15:28:56 2023:03:15 15:29:24 2023:03:15 15:29:28 2023:03:15 15:37:36 2023:03:15 15:38:15 2023:03:15 16:16:13 2023:03:15 16:21:34 2023:03:15 16:21:37 2023:03:15 16:26:35 2023:03:15 10:11:14 2023:03:15 10:11:59 2023:03:15 10:15:13 2023:03:15 10:21:41 2023:03:15 10:24:28 2023:03:15 10:24:30 2023:03:15 10:26:49 2023:03:15 10:54:05 2023:03:15 11:00:04 2023:03:15 11:17:26 2023:03:15 11:30:33 2023:03:15 11:33:55 2023:03:15 11:34:19 2023:03:15 11:57:04 2023:03:15 12:05:44 2023:03:15 12:14:54 2023:03:15 12:20:03 2023:03:15 12:23:31 2023:03:15 12:23:58 2023:03:15 12:26:36 2023:03:15 14:28:34 2023:03:15 14:34:27 2023:03:15 14:39:12 2023:03:15 14:47:43 2023:03:15 14:51:36 2023:03:15 14:51:50 2023:03:15 14:56:46 2023:03:15 15:15:36 2023:03:15 15:25:54 2023:03:15 15:33:57 Description A36 by stormwater channel with hole (exposed waste under) Exposed waste A37 erosion A37 erosion A37 erosion A38 LC5 A39 AFV-1/IV-14, bare earth and waste A41 GW-50R A42 GW353 at exposed skirt A42 GW353 at exposed skirt A43 erosion B1 bare earth B1 bare earth Leachate breakout with discolored soils and bare earth and exposed waste B2 distressed vegetation B3 broken pipe sticking out of cover / bare soils and distressed vegetation B3 broken pipe sticking out of cover / bare soils and distressed vegetation B4 GW113R B5 GW102 B6 distressed vegetation B7 sump missing cover cap B8 GW512 B9 exposed waste B9 bare earth B10 GW529 exposed skirt B11 GW235R with discolored soils B12 distressed vegetation B13 gully washout B14 leachate sump, leachate breakout B14 leachate sump, leachate breakout B14 leachate sump, leachate breakout B15 GW628 exposed skirt B16 GW623 torn exposed skirt B17 bare earth B18 GW55R2 B19 bare earth/exposed waste B19 bare earth/exposed waste B20 GW334R B21 Ponded leachate with bubbling, algae, and exposed waste B22 bubbling through liquids and discolored soils Large erosion gulley Page 10 of 17 Image Log continued (3/3) Image # File Name 81 R0010040.JPG 82 R0010041.JPG 83 R0010042.JPG 84 R0010043.JPG 85 20230315_162337.mp4 86 20230315_162355.mp4 87 R0010038.MOV Date/Time (Central) 2023:03:15 15:44:50 2023:03:15 15:50:42 2023:03:15 15:51:06 2023:03:15 15:56:45 2023:03:15 16:23:37 2023:03:15 16:23:55 2023:03:15 15:26:00 Description B24 Leachate riser LCR3-1 B25 Leachate risder LCR3-2 B25 Leachate risder LCR3-2 B26 Leachate riser LCR 3-3, distressed vegetation Video, B30 landfill gas bubbling through liquids Video, B30 landfill gas bubbling through liquids Video, B22 landfill gas bubbling through liquids / discolored soils Page 11 of 17 APPENDIX B: FIELD MEASUREMENT DATA Measured Exceedances (1/4) Reading Reading Flag 1 2 Description Leachate Riser LCR-2-2, ground surrounding riser and at riser cover A1 2,242 1,100 interface. Latitude Longitude 29.95393088 -95.24338648 A2 2,500 10,100 VC-14-3, ground around base of well. 29.95388494 -95.24271349 A3 700 A4 9,000 A5 7,000 A6 2,800 A7 2,800 1,100 3,900 5,000 1,400 4,500 Around edge of tarp. Unidentified Riser upslope of A3 and A5. GW-114R base of well. Possible previous corrective action observed. IV-5; IV-4; IV-6. Multiple pipe-cover penetration interfaces. Area in the vicinity of grid marker BB, bare ground surrounded by distressed veg. 29.95407413 29.95419534 29.95420071 29.9534413 29.95393461 -95.24211568 -95.24219929 -95.24233667 -95.24228618 -95.24099483 A8 2,500 A9 - 2,200 Flame Out GW 11-117 base around well. Pneumatic pump venting uncontrolled LFG. Riser H265. No confirmation due to intermittent venting 29.95400226 29.9540614 -95.24084165 -95.23930727 A10 2,200 A11 870 2,900 1,300 H2-7S - base of well/riser. Bare patch of eroded slope facing ESE. 29.95417891 -95.23902268 29.95607202 -95.23964798 A12 3,500 4,800 DW-656 both riser penetrations. 29.95649218 -95.24050206 A13 880 A14 2,400 1,800 1,800 Bare patch of ground. Multiple mattresses penetrating cover near well GW-656A 29.95637869 -95.2404873 29.95613738 -95.24105193 A15 1,100 A16 1,200 A17 9,000 1,300 950 1,100 bare ground Mattresses and other proximate flagging. GW-664 both riser and well-cover interfaces. 29.95605038 -95.2415046 29.95595503 -95.24142813 29.95618074 -95.24221027 A18 585 720 Area with exposed waste. 29.95657512 -95.24376021 A19 1,000 650 Around the base of a capped well. 29.95635372 -95.24374299 A20 699 1,000 Erosion/rivulet. 29.95578432 -95.24423093 Page 12 of 17 Measured Exceedances, continued (2/4) Reading Reading Flag 1 2 Description Erosion gulley. Leachate seep visible A21 3,700 2,200 in area. Latitude Longitude 29.95530209 -95.24496742 A22 2,400 1,200 A23 600 A24 1,100 A25 2,500 A26 3,900 A27 18,000 1,200 6,000 3,500 3,500 1,300 Erosion gulley. ATP2-0001. Base. Also Vented LFG from taped connector on wellhead (2.6%) GW-528 base of well and ground between well and lateral. Base of leachate collector (undesignated). LCR 2-3 broad area where leachate is leaking below the sump riser. Around base of leachate collectors (undesignated). 29.95497964 29.95501617 29.95503169 29.95436407 29.95429706 29.96109487 -95.24423902 -95.24392339 -95.2438455 -95.24428535 -95.24430373 -95.24155866 A28 3,400 A29 8,700 1,200 12,000 Broad area of slope erosion. GW-338 Two gullies bordering wellhead and lateral. 29.96081441 -95.24099711 29.96087482 -95.24088261 A30 2,500 5,900 Gulley. 29.96096572 -95.24092616 A31 5,900 900 Gulley. 29.9609227 -95.24052087 A32 1,100 700 Erosion on slope. 29.96088216 -95.24060594 A33 8,000 1,000 Erosion on slope. 29.96089092 -95.24029912 A34 1,700 3,000 GW-336-R2 base of well. 29.96105169 -95.240087 A35 700 A36 1,200 1,100 1,500 erosion/gulley Stormwater BMP-hole in the middle of the poly. 29.96140843 -95.24049209 29.96134753 -95.24071061 A37 900 1,800 erosion/gulley 29.96134948 -95.24127161 A38 1,300 1,000 LC-5 29.96138849 -95.24157732 A39 800 1,100 AFV-1/IV-14 base of header valves. 29.96139911 -95.24161363 A40 670 7,000 ATV WO43 29.96125128 -95.24199058 A41 864 740 GW-50R around base of well. 29.96041875 -95.24435817 A42 1,400 1,400 GW-353 29.9605312 -95.2442025 A43 1,080 580 Access road tire track erosion Page 13 of 17 29.96019947 -95.24386996 Measured Exceedances, continued (3/4) Reading Reading Flag 1 2 Description B1 950 1,058 Surface B2 936 800 Surface B3 1,348 8,000 Inside and outside of broken pipe B4 714 1,300 GW113R B5 2,322 2,350 GW102 B6 758 B7 1,600 1,140 - Surface near distressed vegetation Sump missing cover cap, readings fluctuate with pump action. No confirmation due to intermittent venting. B8 1,386 700 B9 1,182 800 GW512 Surface in rut caused by erosion/runoff (multiple points in area) B10 1,799 B11 1,289 B12 2,600 B13 5,415 B14 2,700 700 630 12,000 21,000 5,000 GW539 at end of skirt GW235R Surface area with no vegetation/washout Gully washout with no vegetation (6000 ppm at knee level) At leachate sump, leachate coming out of ground B15 1,561 B16 3,300 B17 600 B18 1,700 B19 743 B20 1,675 B21 1,130 2,500 800 800 800 4,000 800 1,500 GW628 GW623 at tear in skirt Surface GW55R2 Surface, exposed waste in area GW334R Low spot with ponded leachate, bubbling gas observed Page 14 of 17 Latitude Longitude 29.95437869 -95.24335681 29.95444949 -95.24288924 29.95447712 -95.242756 29.95434771 -95.24276179 29.95457584 -95.24030923 29.95456414 -95.23983519 29.95463602 -95.23900029 29.95562508 -95.23943244 29.95573346 -95.2395326 29.95576623 -95.24318039 29.95563285 -95.24425103 29.95552744 -95.24536191 29.95540963 -95.24515706 29.95481793 -95.24547246 29.96020154 -95.24129252 29.96028578 -95.2404931 29.96041781 -95.24018809 29.96060631 -95.23966077 29.96081152 -95.23975861 29.96110612 -95.23968922 29.96197606 -95.2412968 Measured Exceedances, continued (4/4) Reading Reading Flag 1 2 Description B22 1,246 B23 2,600 3,700 700 Surface with bubbling from hole Near CS5 condensate sump, also detect at base of condensate sump B24 1,788 1,635 Leachate riser LCR 3-1 Latitude Longitude 29.96184121 -95.24166222 29.96161943 -95.24251008 29.96181289 -95.24252112 B25 4,000 B26 16,000 B27 4,600 B28 2,364 B29 1,506 B30 1,591 B31 3,500 B32 2,100 2,200 10,000 9,000 1,200 3,500 604 12,000 2,776 (2200 reading was 10 cm from ground) Leachate riser LCR 3-2 13,000 - 30,000 ppm coming from leachate riser piping, multiple points LCR 3-3 leachate riser, 16,000 ppm 2 inches above ground, 10,000 ppm 3 ft away from pipe Near Leachate riser 3-4 (15,000 ppm coming from pipe in ground) Surface 500 ppm 2 ft away CS6 Condensate sump Surface, liquids ponded and bubbling Widespread area with erosion no vegetative cover (three separate flagged spots) GW637 multiple penetration points with detects 29.96180631 29.96180802 29.96177827 29.96179968 29.9614741 29.95979127 29.95991283 29.9598359 -95.24326273 -95.24417422 -95.244968 -95.24506524 -95.24553927 -95.24489846 -95.24456571 -95.24369572 Calibration and Instrument Information EPA used three ThermoFisher Toxic Vapor Analyzers 2020 (TVA2020), numbered 202017092712, 202023016408, and 202016081525 (and designated as TVAs "Green", "Red" and "Black"). The EPA TVA2020 response times are approximately 4.5 seconds. EPA calibrated with 500 ppm methane in air and zero gas. Bump Checks 08:30 initial calibration 13:35 mid-day drift check 13:35 after re-calibration 16:50 end of day drift check TVA Green 501 433 520 520 TVA Red 494 415 501 508 TVA Black 493 448 500 494 Background readings: Upwind: 0 ppm Downwind: 4 ppm Page 15 of 17 APPENDIX C: MAPS Site Overview Map Blue line roughly shows EPA survey coverage, tracing the confirmation reading instrument. Active area at far eastern end of South Hill. Satellite imagery dated to April 2022 as shown on Google Earth. Page 16 of 17 Map of Detected Exceedances: Afternoon, North of North Hill Blue line roughly shows EPA survey coverage, tracing the confirmation reading instrument. Exceedance locations labeled with their flag numbers. Yellow line is 50m, north is up. Satellite imagery dated to April 2022 as shown on Google Earth. Survey area covered less than 33 acres. Map of Detected Exceedances: Morning, South of North Hill Blue line roughly shows EPA survey coverage, tracing the confirmation reading instrument. Exceedance locations labeled with their flag numbers. Yellow line is 50m, north is up. Satellite imagery dated to April 2022 as shown on Google Earth. Survey area covered less than 52 acres. Page 17 of 17